17- Trouma & ER Refrence Flashcards
What does the CCrISP three-stage assessment process help with?
Defining the acuity of patients, identifying underlying problems, determining necessary interventions, and establishing the frequency of patient reviews
What does CCrISP help with in managing surgical patients?
Performing organized simultaneous resuscitation, diagnosis, and definitive treatment
What are “track and trigger” systems used for in hospitals?
To aid in the recognition of deteriorating patients, such as the National Early Warning Score (NEWS)
What is the role of the CCrISP course and three-stage assessment process?
To properly assess acutely unwell patients, plan their subsequent care, and ensure simultaneous resuscitation and diagnosis
What should be done for patients who are relatively stable but at risk of deterioration?
They should be re-evaluated and have their management plan updated at least twice daily
When should the three-stage assessment process be applied to patients?
During scheduled ward rounds and in the event of deterioration
What is the CCrISP system of assessment used for?
To determine whether patients are stable or unstable and guide attention to detail in treatment
What is the predictable pattern of life-threatening illnesses?
Obstruction of the airway kills more quickly than lung problems, which kill more quickly than isolated hemorrhage
What does the immediate management process prioritize?
Assessment and treatment of the airway, breathing, circulation, dysfunction of the CNS, and exposure of the patient for full assessment
What are the steps of the ‘Look, Listen and Feel’ clinical assessment for airway obstruction?
Look for central cyanosis, abnormal breathing patterns, use of accessory muscles, tracheal tug, changes in consciousness, and obvious obstructions. Listen for abnormal sounds. Feel for air flow on inspiration and expiration
What precaution should be taken when performing airway maneuvers in patients with a risk of cervical spine pathology?
Maintain manual in-line immobilization of the cervical spine
What should be the immediate goal if objective signs of airway obstruction are present?
To secure the airway, provide adequate oxygenation, and prevent hypoxic brain damage
What are some simple methods to obtain an airway?
Chin lift or jaw thrust to open the airway, suction to remove secretions, and insertion of an oral Guedel airway or a soft nasopharyngeal airway
How can you determine respiratory distress or inadequate ventilation?
Using the ‘Look, Listen and Feel’ technique
What should you look for during breathing assessment?
Central cyanosis, use of accessory muscles, respiratory rate, equality and depth of respiration, sweating, raised jugular venous pressure (JVP), chest drains, and paradoxical abdominal movement
What should you do if signs of immediately life-threatening conditions are present?
Identify and treat them without delay, such as tension pneumothorax, massive haemothorax, open pneumothorax, flail chest, and cardiac tamponade
What should you listen for during breathing assessment?
Noisy breathing, coughing to clear secretions, ability to speak in complete sentences, abnormal breath sounds, heart sounds, and rhythm
What should you feel for during breathing assessment?
Equality of chest movement, position of the trachea, presence of surgical emphysema or crepitus, paradoxical respiration, and tactile vocal fremitus if indicated
What should you consider as potential diagnoses during breathing assessment?
Bronchial obstruction, bronchoconstriction, pulmonary embolism (PE), cardiac failure, and unconsciousness
What should you do if the patient is tiring to the point of respiratory arrest?
Assist ventilation with a bag/mask and perform necessary airway maneuvers until help arrives
What should be considered as the primary cause of circulatory dysfunction in surgical patients?
Hypovolaemia
What is the first step in assessing a patient with circulatory dysfunction?
Rapidly exclude haemorrhage and establish adequate venous access
What is the recommended fluid challenge for normotensive patients?
10ml/kg of warmed crystalloid
What is the recommended fluid challenge for hypotensive patients?
20ml/kg
How can life-threatening circulatory dysfunction be recognized?
Reduced peripheral perfusion, external haemorrhage, and concealed haemorrhage
How can perfusion be assessed?
By measuring capillary refill time
What should be done if a patient is not responding to fluid resuscitation?
Immediate intervention and different treatment
What are the three categories that shocked patients fall into?
Exsanguinating patients, unstable patients, and patients with a relatively minor problem
When should reassessment be performed?
After each intervention
What is the recommended resuscitation fluid for bleeding patients with cardiovascular instability?
Blood
What should be done if a patient is not responding to resuscitation?
Call for senior help, cross-match blood, and prepare for surgery
What are some possible causes of altered consciousness level in surgical patients other than a primary brain injury?
Hypoxia, cerebral underperfusion due to shock, recent administration of sedatives, analgesics, or anaesthetic drugs, and hypoglycaemia
How can the neurological status of a patient be rapidly determined during the initial assessment?
By examining the pupils and using the AVPU system: A - Alert, V - responds to Verbal stimulus, P - responds only to Pain, U - Unresponsive to any stimulus
What should be done for shocked or hypotensive patients who are not bleeding?
Avoid blindly giving large amounts of fluid and seek a clear diagnosis and plan
What should be done if the patient is not fully conscious despite considering other causes?
Reassess and review the ABCs (Airway, Breathing, Circulation) to ensure no missed factors
What should be considered when exposing the patient?
Preserving the patient’s dignity and being aware of the risk of the patient becoming cold
What signs should the patient ideally be showing by the end of the immediate assessment and management phase?
Signs of improvement and progressing out of immediate danger
What should be ensured before moving on to the next phase?
The patient should be receiving oxygen and IV fluids, monitoring should be established (pulse oximeter, blood pressure), and oxygen saturation (SaO2) should be above 94%
What should be done if the patient is not showing signs of improvement by this stage?
Call for help and consider transferring the patient to the operating theatre or intensive care
What investigations should be arranged at this stage?
Pressing investigations that have not been done recently and are integral to the immediate assessment, such as arterial blood gases (ABGs), chest X-ray, or ECG
What further actions may be necessary at this stage?
Inserting a urinary catheter if appropriate, alerting senior colleagues if not already done, and quickly reassessing the ABCs
What should be done if the patient’s condition is not deteriorating?
Use the time to continue with the next stage of assessment to determine the underlying cause of deterioration
What should be done if the patient’s condition is deteriorating?
Quickly reassess, call for help, and arrange for further immediate treatment as appropriate
What should be considered during the assessment of a surgical patient?
General aspects of care (cardiorespiratory function, fluid balance) as well as specific aspects related to the surgery (e.g., bile production or drainage, liver function tests, albumin, glucose, clotting factors)
What should be assessed in the respiratory category?
Respiratory rate, inspired oxygen concentration (FiO2), and oxygen saturation (SaO2)
What should be assessed in the circulation category?
Heart rate and rhythm, blood pressure, urinary output, fluid balance, intravenous lines, and cardiac output measurements
What should be considered in the surgical category?
Special requirements specific to the operation, temperature, and drainages (nature and volume)
How should patients about whom you are unsure be managed?
They should be managed as if they were unstable
What is the recommended format for a systematic examination?
It should follow a standard format, starting with the hands and proceeding to the neck, chest, abdomen, limbs, and any wounds or stomas that may require examination
What should be considered when formulating a management plan for stable patients?
Prescribing necessary therapeutic drugs, checking for appropriate prophylaxis, verifying the need for antibiotics, ensuring routine medications are given, and considering comorbid conditions and their implications
What are the characteristics of stable patients?
They have normal signs, are progressing as expected, and have not experienced recent complications
What are the components of the daily plan?
What are the components of the daily plan?
What is the underlying aim of critical care practice?
To begin definitive treatment of life-threatening pathology or complications as quickly as possible
What information should be included in the case notes?
Who saw the patient, why they were seen, information gathered and interpreted, the decision and plan, who will carry it out, and the date of the next review. Additionally, any communication with the patient and their concerns may be recorded if necessary
What is the most common reason for admission to a critical care unit?
Provision of airway management and ventilatory care to critically ill patients
What does the CCrISP system encourage?
Assessing patients in a similar way, identifying those in need of immediate life-saving resuscitation, reaching a diagnosis, formulating and instituting a plan of definitive treatment, planning selective and safe investigations, utilizing repeated clinical assessment, involving senior colleagues, considering the level of care necessary, and communicating and documenting clearly
What are the signs of airway compromise that indicate the need for intervention?
Noisy breathing, inspiratory stridor, seesaw breathing, indrawing of suprasternal, supraclavicular, and intercostal spaces
What are the two golden rules of airway management?
Always give oxygen in the highest concentration possible and use simple methods of airway management first
What is the recommended method for administering oxygen to a spontaneously breathing patient?
Using a mask with a reservoir bag to deliver the highest flow rate of oxygen possible
Why is administering high concentrations of oxygen not a concern during resuscitation?
Hypoxia is more dangerous than the loss of respiratory drive, and the occurrence of a hypoxic drive is rare in surgical patients
What is the target saturation range for maintaining adequate saturations in stable patients?
> 94% (unless there is evidence of a hypoxic drive, in which case the range is 88-92% as recommended by the British Thoracic Society)
What is the limitation of pulse oximetry in assessing ventilation?
It does not provide information about hypercapnia or the effectiveness of ventilatory effort
What are the escalating measures for airway support?
Chin lift/jaw thrust, suction, oropharyngeal/nasopharyngeal airways, laryngeal mask or endotracheal tube, surgical airway
What are the basic manoeuvres that can improve gas exchange through a compromised airway?
Chin lift/jaw thrust without airway adjuncts
What should be inserted if basic manoeuvres are not sufficient to improve gas exchange?
An oral Guedel airway
How should a Guedel airway be inserted in adults?
Upside down and rotated into place over the tongue, sized from the tragus of the ear to the angle of the mouth
What is necessary for ventilation if the patient is apneic or has shallow respiration?
Using a bag/valve/mask system
What can be attempted as an alternative to intubation in certain situations?
Insertion of a laryngeal mask airway
What should be done if intubation fails or manual ventilation is not possible?
Perform a surgical airway by surgical cricothyroidotomy for life-saving oxygenation and ventilation
What is a tracheostomy?
A hole in the trachea through which a person can breathe or be ventilated
What are the two distinct types of tracheostomy?
1) Tracheostomy after laryngectomy (upper airway absent) 2) Surgical tracheostomy or percutaneous dilational tracheostomy (upper airway present)
Where are tracheostomies often performed?
On long-stay ICU patients
What should be checked for each type of tracheostomy tube?
Tube size, length, and dimensions
What are the recommended tube sizes for females and males?
Females: 7-8mm internal diameter tube; Males: 8-9mm internal diameter tube
Why is selecting the appropriate tube size important?
To maximize internal tube dimensions and reduce the work of breathing through the tube
What is the risk of using an oversized tracheostomy tube?
Pressure necrosis and damage to the tracheal mucosa
What is the purpose of the aspiration port above the cuff in cuffed tracheostomy tubes?
To keep the area clear of secretions and reduce the risk of ventilator-acquired pneumonia
Why is humidification and regular suction essential for tracheostomy patients?
To prevent blockage of the tracheostomy tube
How long should tubes be changed after a surgical procedure or percutaneous procedure?
Surgical procedure: at least 3 days; Percutaneous procedure: ideally 7-10 days
Why are single lumen tubes generally undesirable on the wards?
Due to the risk of blockage
What should single lumen tubes be replaced with?
Tracheostomy tubes with a removable inner tube for easier cleaning
What algorithm can be used to determine if the tracheostomy tube is still required?
The CCrISP algorithm
What is the most important difference between a laryngectomy stoma and other forms of tracheostomy?
In a laryngectomy stoma, there is no remaining upper airway
What are some reasons for a tracheostomy?
Upper airway obstruction, post laryngectomy/upper airway surgery, musculoskeletal disorders affecting ventilation, assist weaning from ventilation, incompetent swallow/impaired upper airway reflexes
What are the different types of tracheostomy tubes available?
Cuffed, uncuffed, unfenestrated, fenestrated
What are the common problems with tracheostomies?
Displacement, obstruction, haemorrhage
What should you do if you haven’t received training to change tracheostomy tubes?
Do not plan to undertake the procedure unsupervised
How should haemorrhage from a tracheostomy tube be managed?
Call for help, apply 100% oxygen, inspect stoma site, apply manual pressure to bleeding sites, consider dilute adrenaline infiltration, apply pressure to sternal notch and hyperinflate tracheostomy cuff if bleeding is significant
What should be done in case of desaturation with a tracheostomy and an existing airway?
Call for help, administer 100% oxygen, assess tracheostomy patency, manage upper airway, attempt bag and mask ventilation at tracheostomy stoma site, perform upper airway intubation (by skilled clinician)
Call for help, apply 100% oxygen, inspect stoma site, apply manual pressure to bleeding sites, consider dilute adrenaline infiltration, apply pressure to sternal notch and hyperinflate tracheostomy cuff if bleeding is significant
Securing the airway
What tests should be performed in case of tracheostomy-related bleeding?
Full blood count (FBC), ABG analysis, cross-matching
What is the process called when removing a tracheostomy tube?
Decannulation
What is the recommended post-removal care for dilational percutaneous tracheostomies?
Occlusive stoma site dressing
What factors should be assessed before removing a tracheostomy tube?
Neurological status, ventilation and oxygenation needs, quality of upper airway, ability to cough and clear secretions, successful treatment of the original indication for tracheostomy, overall stability of the patient
What may be required for surgical tracheostomies after removal?
Formal operative closure
What assessments may be needed before resuming an oral diet?
Formal speech and language therapy and swallowing assessments
What are the common complications of tracheostomies?
Displacement, obstruction, haemorrhage (DOH)
What is the critical point on the oxygen dissociation curve for rapid desaturation to occur?
PaO2 of 8kPa
What determines if Type 2 respiratory failure is acute or chronic?
Bicarbonate level and patient’s history
What is respiratory failure?
Inadequate pulmonary gas exchange resulting in abnormal blood oxygen and carbon dioxide levels
What are common causes of respiratory failure in surgical patients?
1) Acute fall in functional residual capacity (FRC) without pulmonary vascular dysfunction, 2) Acute fall in FRC with pulmonary vascular dysfunction, 3) Airflow obstruction
How is respiratory failure classified based on CO2 levels?
Type 1 failure: Hypoxia with normal or reduced PaCO2; Type 2 failure: Hypoxia and hypercarbia
What factors increase the risk of respiratory problems?
Pre-existing respiratory disease, obesity, smoking, thoracic surgery, upper abdominal surgery, older age
How can patients with respiratory failure be easily recognized?
Dyspnea, tachypnea, apnea, inability to speak in complete sentences, use of accessory muscles of respiration, central cyanosis, sweating and tachycardia, decreased level of consciousness
What is the recommended initial oxygen therapy for patients who are still spontaneously breathing?
High-flow oxygen via a reservoir bag
What is the rule for oxygen therapy once the patient has stabilized?
Give the minimum added oxygen necessary to achieve optimal oxygenation
What should be considered during resuscitation in terms of oxygen therapy for patients with chronic pulmonary disease?
Do not worry about potentially depressing ventilation; prioritize preventing hypoxia over hypercarbia
What is the purpose of pulse oximetry in the monitoring of critically ill surgical patients?
To continuously monitor oxygen saturations
How does pulse oximetry work?
It combines principles of light transmission and reception through tissue to detect pulsatile flow and differentiate between oxygenated and reduced hemoglobin
What does pulse oximetry display?
Heart rate and arterial oxygen saturation (SaO2)
Does saturation equate to the partial pressure of oxygen?
No, saturation does not equate to the partial pressure of oxygen responsible for gas exchange
What is the advisable SaO2 level to maintain?
Above 94%
What is the potential delay between actual and displayed values in pulse oximetry?
Around 20 seconds
What can impede accurate pulse oximetry readings?
Movement, peripheral vasoconstriction, cardiac arrhythmias, profound anemia, SaO2 below 70%, diathermy, bright lights, dirty skin or pigmentation, use of nail varnish
What should be assessed during chart examination in a patient with respiratory problems?
Changes in respiratory rate, temperature, pulse rate, blood pressure, level of consciousness, oxygen saturation, ABGs, fluid balance
What information should be obtained from the patient regarding respiratory difficulty?
Changes in the color or amount of sputum
What is the initial approach to examine the patient for respiratory problems?
Clinical examination using “Look, Listen, and Feel” techniques
How can correction of anemia impact oxygen delivery to tissues?
It can improve oxygen delivery to the tissues if the hemoglobin is less than 80g/L
Which blood test is most useful in cases of respiratory failure?
ABG analysis
What can an elevated white cell count in the blood indicate?
Concurrent infection, potentially of pneumonic origin
When should CT pulmonary angiography (CTPA) be used?
When a patient is hypoxic and there is no clear cause for the deterioration
What lung function tests are useful in predicting a patient at risk?
Peak expiratory flow rate, vital capacity, and forced expiratory volume in 1 second (FEV1)
What is the most common cause of respiratory failure?
Infection
What samples should be obtained before commencing antibiotic therapy in cases of respiratory failure?
Blood samples for culture
What should be assessed in stable patients as part of the daily management plan?
Respiratory rate, SaO2, cyanosis, ability to cough and deep breathe, adequacy of analgesia, signs of respiratory distress, sweatiness, tachycardia, and regular chest examination
What should be assessed during a chart review in a patient assessment?
Changes in respiratory rate, temperature, pulse rate, blood pressure, level of consciousness, oxygen saturation, and ABGs
What measures can be taken to prevent respiratory problems in patients at risk?
Early mobilization, sitting up, patient positioning, exercises to encourage deep breathing, suction of respiratory secretions, and use of devices such as incentive spirometry and cough incentive machines
What should be prescribed for stable patients requiring oxygen therapy?
Humidified oxygen therapy by mask at an appropriate concentration
What should be prescribed for patients who develop wheezing?
Nebulized salbutamol and ipratropium
Why is adequate analgesia important in respiratory patients?
To enable patients to cough and deep breathe
What are the steps for preventing respiratory deterioration following surgery?
- Identify those at risk. 2. Examine and assess. 3. Encourage early mobilization. 4. Provide adequate analgesia. 5. Arrange for chest physiotherapy. 6. Administer nebulized saline. 7. Administer humidified oxygen at a titrated dose. 8. Take sputum for culture. 9. Reassess regularly.
Why is a chest radiograph important in the management of critically ill patients?
It provides valuable confirmatory and complementary diagnostic evidence (or reassurance) in many clinical scenarios and diagnoses.
What is the recommended view for assessing the heart in a chest X-ray?
A straight, erect posteroanterior (PA) film taken at full inspiration
What are the components of the example system for assessing a chest X-ray?
- Soft tissues (air, foreign bodies, disruption of contours). 2. Bony structures (ribs, clavicles, scapulae, sternum). 3. Lung markings (extension to chest wall, presence of pneumothorax or haemothorax, volume of parenchyma). 4. Examine lung fields for opacities. 5. Check costophrenic angles for fluid. 6. Look for air beneath the diaphragm and intra-abdominal abnormalities. 7. Note position of trachea and heart size, check mediastinum and presence of tubes or lines.
What does the presence of an air bronchogram suggest?
Oedema, infection, or other infiltrates in the surrounding lung tissue
What are Kerley B lines?
Horizontal lines that meet the pleural surface at right angles, caused by increased fluid or tissue within the intralobular septa
What are the signs of pleural effusion on a chest X-ray?
Blunting of the costophrenic angle, lung compression, displacement of the mediastinum to the opposite side, and flattened diaphragm on the affected side
Can bronchitis and emphysema be present without chest X-ray abnormalities?
Yes
What are some possible chest X-ray findings in bronchitis and emphysema?
Increased lucency of the lung, regional or general loss of vascularity in the peripheral lung fields, and increased size of the lung fields
Why may an effusion appear as a faint diffuse opacity on a supine chest X-ray?
Because the fluid is spread thinly over a wide area
What should be done to confirm an effusion if it is not clearly visible on a supine chest X-ray?
Repeat the X-ray after the patient has been sitting up for 15 minutes or obtain an ultrasound scan
What conditions may cause an enlarged cardiac silhouette on a chest X-ray?
Ventricular hypertrophy, pericardial effusion, and ventricular aneurysm
What can be done to confirm a pericardial effusion if there is doubt?
Echocardiography
What are some signs of cardiac failure on a chest X-ray?
Upper lobe blood diversion, cardiomegaly, pleural effusions, Kerley B lines, and parenchymal shadowing (diffuse or hilar ‘bat’s-wing’ shadowing)
What should be the initial treatment for respiratory failure?
Conventional mask oxygen therapy
Up to what inspired oxygen concentration are fixed-delivery oxygen masks available?
60% (FiO2 of 0.6)
Why should all oxygen delivery systems be humidified?
To prevent thickening of the patient’s secretions and promote sputum retention
What can help prevent worsening of incipient respiratory failure?
Nebulized 0.9% saline (with bronchodilators if indicated) and regular treatment from a respiratory physiotherapist
What is the importance of treating the underlying cause of respiratory failure?
Oxygen is only one aspect of treatment; treating the underlying cause is necessary
What are high-flow nasal oxygen therapy devices?
Devices that provide higher flows and concentrations of oxygen than conventional facemasks, along with gas humidification
What treatments may be needed for respiratory failure?
Appropriate antibiotics, physiotherapy, diuretics, bronchodilators, and cardiac or other drugs as necessary
What factors should be considered in treating respiratory function?
Systemic factors (mobility, nutrition) and clearance of secretions
What should be considered if the patient has confusion or a depressed level of consciousness?
Hypoxia and hypercarbia as possible causes, rather than assuming it is due to opiate analgesia
What are some indications of failure of mask oxygen therapy at high FiO2?
Increasing respiratory rate, increasing distress, dyspnea, exhaustion, sweating, confusion, oxygen saturation 80% or less (late sign), PaO2 less than 8kPa, and PaCO2 greater than 7kPa
What should be done if a patient is tachypneic and showing signs of tiring and arrest?
Intervene before this stage by acting on early symptoms and signs, particularly tachypnea, and transfer the patient to a higher level of care for further therapy to improve gas exchange
Who should be closely monitored for potential problems in respiratory failure?
Patients with severe chronic lung disease (e.g., vital capacity less than 15ml/kg or FEV1 less than 10ml/kg)
What may be required for frequent blood gas analysis in patients with respiratory failure?
Insertion of an arterial line
What is the purpose of CPAP (Continuous Positive Airway Pressure)?
To help with type 1 respiratory failure
What is the range of airway pressure that can be maintained with CPAP?
2.5 to 10cmH2O
How is CPAP administered?
Through a tight-fitting facemask with expiratory valves that maintain a set airway pressure
What are the possible complications associated with CPAP masks?
Nasal pressure sores and gastric dilatation and regurgitation due to air swallowing
What are the benefits of CPAP?
Recruitment of underventilated alveoli, increased functional residual capacity (FRC), decreased intrapulmonary shunt, decreased work of breathing, and improved oxygenation
Who may not tolerate a full-face mask but may be suitable for a nasal mask?
Patients who can keep their mouth closed to prevent loss of pressure
What alternative devices are available for CPAP administration?
Hood devices, which are noisy and can be claustrophobic but do not require patient coordination
How can the CPAP device be connected to a patient with a tracheostomy tube?
Via a T-piece connected directly to the tracheostomy tube
What are signs that a patient may not tolerate CPAP?
Refractory hypoxemia, increasing respiratory rate, progressively smaller tidal volumes resulting in CO2 retention, intolerance of the CPAP device, agitation, or obtundation
What should be considered for the successful use of CPAP?
Patient selection, frequent monitoring (including regular ABGs), and a plan for the duration and frequency of CPAP administration
In what situations can CPAP be used?
As part of the weaning process from formal ventilation or after major surgery to reduce the risk of respiratory complications
How long is the minimum duration of continuous CPAP required for it to be beneficial?
At least 2 hours
What is the term for this type of non-invasive ventilation?
Bilevel positive airway pressure mask ventilation (BIPAP)
What are the two different pressures applied to the patient during non-invasive ventilation by mask?
A higher pressure during inspiration (around 20cmH2O) and a lower pressure during expiration (5cmH2O)
When should non-invasive ventilation by mask be considered?
When type 2 respiratory failure (CO2 retention) develops
How does BIPAP work?
The machine detects the drop in airway pressure during inspiration and adjusts the pressure accordingly, delivering gas flow into the lungs during inspiration
What are the criteria for selecting patients for mask ventilation?
Refractory hypoxemia, increasing respiratory rate, progressively smaller tidal volumes, and worsening CO2 retention
What factors determine the tidal volume delivered during BIPAP?
Lung compliance, duration of inspiration, and driving pressure
How long should mask ventilation be given before determining its success?
If the patient’s CO2 has not improved within 30 minutes, mask ventilation is unlikely to succeed
When can non-invasive ventilation be used post extubation?
In patients with a high risk of reintubation
What is the purpose of intubation and ventilation?
To administer oxygen at high concentrations and adjust tidal volume and respiratory rate to meet the patient’s needs
What is the target tidal volume for patients undergoing intrabdominal procedures?
6ml per kilogram of predicted body weight
How can lung damage be avoided during ventilation?
By using a low tidal volume approach
What factors can help achieve the target tidal volume during ventilation?
Use of sedatives, paralytic agents, and permissive hypercapnia
What are the benefits of high-flow nasal oxygen?
Delivers up to 100% O2 with high flows and high humidity, helps clear secretions, and improves work of breathing
What is the pressure delivered to the patient during high-flow nasal oxygen?
Equivalent to CPAP 5cmH2O
What are the advantages of high-flow nasal oxygen compared to other respiratory support methods?
Well tolerated by patients, allows communication and oral nutrition without interruption
When should intubation be considered for patients receiving high-flow nasal oxygen?
If patients do not improve rapidly
What is the main use of high-flow nasal oxygen in surgical patients?
Treatment of type 1 respiratory failure
What is the purpose of synchronised intermittent mandatory ventilation (SIMV)?
To preserve some of the patient’s respiratory muscle activity by synchronizing ventilation with the patient’s own respiratory effort
When is ‘controlled mandatory ventilation’ mode of ventilation used?
When the patient is fully sedated and requires no active participation in breathing
What are the modern modes of ventilation that reduce the need for heavy sedation and paralysis?
SIMV combined with pressure-controlled ventilation (PCV), pressure support ventilation (PSV), and positive end-expiratory pressure (PEEP)
When is paralysis necessary during ventilation?
In the most difficult to ventilate patients, and only for short periods until control is achieved
What is the purpose of positive end-expiratory pressure (PEEP)?
To prevent airway collapse during expiration and recruit underventilated alveoli
What are the adverse consequences of high peak airway pressure during ventilation?
Decreased venous return, fall in cardiac output, and increased risk of barotrauma, including tension pneumothorax
Why are concentrations of oxygen greater than 80% rarely used?
Because high oxygen concentrations can promote toxic effects, and concentrations above 80% can be harmful
What is the process of volutrauma?
It is the promotion of alveolar and vascular damage, leading to fluid leak and worsening lung compliance
How do pressure control modes of ventilation reduce the risk of barotrauma?
By administering a breath to a set pressure, keeping it below 26cmH2O, and allowing the tidal volume to depend on the patient’s lung compliance
What is the aim of pressure support ventilation?
To provide a higher tidal volume by administering pressure when the patient takes an inspiration
What is permissive hypercapnia?
It is allowing the CO2 levels to rise as long as the pH remains above 7.2, reducing ventilator-induced lung injury and improving survival
What strategies should be combined with lung recruitment strategies like PEEP?
Regular physiotherapy, suction, and turning the patient to prevent alveolar collapse
What is the purpose of adjusting the inspiratory to expiratory (I/E) ratio?
To improve gas exchange by opening poorly compliant alveoli and maximizing gas exchange without causing barotrauma or volutrauma
What is the risk for a patient receiving pressure-controlled inverse ratio ventilation (PCIRV), high FiO2, PEEP >10cmH2O, and permissive hypercarbia who fails to achieve oxygen saturation greater than 85%?
High risk of death, as tissue oxygen delivery fails to meet demand
What can be considered as an adjunct to ventilation for a patient at high risk of death?
Turning the patient from the supine to prone position to redistribute blood flow and improve oxygenation
What interventions can be performed during ventilation to treat the underlying cause of respiratory failure?
Antibiotics and pleural drainage
What is the purpose of weaning from ventilatory support?
To return the patient to spontaneous respiration in a safe and controlled manner
Why should patients be encouraged to participate in ventilation as soon as possible?
Prolonged ventilation can lead to atrophy of the respiratory muscles
What are the conditions that should be met before attempting weaning?
Normal PaO2 with a low inspired oxygen concentration, no CO2 elimination problems, minimal sputum production, normal nutritional status, adequate neuromuscular function, and a reasonably cooperative patient
When is it unwise to attempt weaning from ventilatory support?
Until the underlying cause of respiratory failure has been treated successfully and sedative drugs have been reduced to a level that will not depress respiration
What are the commonly used modes for step-down ventilation during weaning?
SIMV, assisted spontaneous breathing (ASB), and PSV, often used in combination
What is an alternative method for weaning that requires the patient to do all the work of breathing?
Using a simple T-piece for periods of time
How can the ventilator be set during weaning when the patient is breathing spontaneously?
To compensate for the presence of the tube (tube compensation)
What is the typical approach used in critical care units for weaning?
PCV → SIMV → ASB/PSV → CPAP and T-piece, followed by extubation
What are some reasons why patients may fail to tolerate extubation?
Poor airway control, laryngeal edema, poor cough, sputum retention, or simple fatigue
What can be used as part of the weaning process if patients require reintubation or have a decreased level of consciousness?
Tracheostomy
What should be done if the patient deteriorates after ICU discharge?
Contact critical care staff at an early stage for a formal review
What is atelectasis?
Atelectasis is the absence of gas from all or part of the lung.
In which group of patients is atelectasis commonly seen?
Surgical patients, especially those who have undergone abdominal and thoracic procedures.
What factors can exacerbate atelectasis?
Pain and splinting leading to reduced lung expansion, retention of secretions, and distal airway collapse. This is more common in the elderly, overweight individuals, smokers, and those with pre-existing lung disease.
How can atelectasis be prevented in high-risk patient groups?
Preoperative breathing exercises to improve lung expansion, intraoperative care with humidification, ensuring good tidal volumes, and avoiding unnecessarily high FiO2 levels.
What are the symptoms of atelectasis?
Cough, chest pain or breathing difficulty, low oxygen saturations, pleural effusion (transudate), cyanosis (late sign), or tachycardia.
How is atelectasis diagnosed?
By chest x-ray (CXR).
What is the mainstay of treatment for atelectasis?
Physiotherapy, focusing on deep breathing, encouraging coughing, and providing effective analgesia. Incentive spirometer is often used as part of breathing exercises. Mobilization should also be encouraged.
What additional therapy may be beneficial in the treatment of atelectasis?
Early use of high-flow nasal oxygen therapy, if available.
What happens in the lungs during pneumonia?
Pneumonia causes inflammation and abnormal filling of the alveoli with fluid. This is known as consolidation and exudation.
What are the symptoms of pneumonia?
Cough, chest pain, fever, and difficulty in breathing.
What findings may be observed during a physical examination of the lungs in pneumonia?
Decreased expansion of the chest on the affected side, bronchial breathing, or crackles. Percussion over the affected lung may be dulled.
Which bacteria are commonly associated with hospital-acquired pneumonia?
Resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas spp., Enterobacter spp., and Serratia spp.
What is ventilator-associated pneumonia?
A subset of hospital-acquired pneumonia that occurs after 48 hours of mechanical ventilation.
What is the risk associated with pneumonia?
A high risk of developing respiratory failure and triggering Acute Respiratory Distress Syndrome (ARDS).
What is the CURB 65 score used for?
Assessment of severity in community-acquired pneumonia. It evaluates Confusion, Urea >7mmol/L, Respiratory rate >30 per minute, Blood pressure (SBP <90mmHg or DBP <60mmHg), and age >65 years. Although not designed for surgical patients or those with hospital-acquired pneumonia, it can provide useful information regarding the severity of the condition and the need for additional critical care support.
What are chest drains used for?
Chest drains are inserted for pneumothorax or drainage of pleural fluid.
What are the two main types of chest drains?
Seldinger-type chest drains are used for drainage of pleural effusions and small pneumothoraces, while traditional drains are used for larger pneumothoraces.
What determines the size of the chest drain used?
The size of the chest drain used depends on the indication. A large-bore tube (28-30F) is used for haemothorax, large and/or tension pneumothorax, while a smaller calibre tube (10-14F) is used for pleural effusions.
Why is maintenance of patency important for chest drains?
Maintenance of patency is important for safety. Larger tubes may be inserted if there is any doubt, but they are associated with increased pain.
What should be monitored for chest drains?
Chest drains should be monitored for swinging, draining, and bubbling, and should have an underwater seal.
What should be considered when patients are ventilated in relation to pneumothorax?
Caution must be used when patients are ventilated, including CPAP and NIV, as recurrence of pneumothorax is common and they may develop tension pneumothoraces.
What information can arterial blood gases (ABGs) provide in the assessment of critically ill surgical patients?
ABGs can provide information on acid-base status, ventilation, global tissue perfusion, and the effectiveness of compensatory mechanisms.
What should be considered in patients with severe COPD regarding oxygen therapy?
A small group of patients with severe COPD rely on hypoxemia to drive their ventilation, and high inspired oxygen concentrations may suppress ventilation and cause hypercapnia. However, in the acute phase of critical illness, oxygenation is imperative, and patients should not be denied oxygen for fear of loss of their respiratory drive.
What does acid-base status affect in the body?
Acid-base status affects blood pH, ventilation (through oxygen and carbon dioxide partial pressures), and tissue perfusion (through base excess/deficit and lactate levels).
What can assist in the management of patients with severe COPD and the potential for causing hypercapnia?
Clinical progress and serial ABG measurement can assist in the management of these patients. Trainees should seek appropriate advice and help if unsure about the potential for causing hypercapnia.
What additional information can blood gas analyzers provide?
In addition to ABGs, blood gas analyzers can provide information on lactate, hemoglobin, potassium, sodium, calcium, and glucose levels.
How are ABG samples obtained?
ABG samples are obtained by arterial puncture (usually the radial artery) or from an arterial line (a-line).
What is the PaO2/FiO2 ratio used for?
The PaO2/FiO2 ratio is used to assess for relative hypoxemia. A ratio of less than 40kPa is considered hypoxic.
How does the production of carbon dioxide and acid affect the binding of oxygen to hemoglobin?
The production of carbon dioxide and acid reduces the affinity of oxygen for hemoglobin, making it less tightly bound and enhancing its off-loading into cells.
What happens to the PaO2 as the FiO2 increases?
As the FiO2 increases towards 1.0 (100% oxygen), the PaO2 should increase as well.
What role does 2,3-diphosphoglycerate (2,3-DPG) play in the binding of oxygen to hemoglobin?
2,3-DPG, present in red blood cells, further loosens the bonds between hemoglobin and oxygen, facilitating off-loading of oxygen into tissues.
What happens to the binding of oxygen to hemoglobin in the lungs?
In the lungs, the binding between hemoglobin and oxygen is increased, allowing for oxygen uptake.
What is the normal concentration of hydrogen ions (H+) within the body?
The concentration of hydrogen ions within the body is normally tightly controlled at 40nmol/L, which corresponds to a pH of 7.42.
What does the PaCO2 value indicate in ABG values?
The PaCO2 value provides information about the absolute ventilatory state of a patient and possible respiratory compensatory mechanisms.
What is the normal range for HCO3- in ABG values?
The normal range for HCO3- (bicarbonate) in ABG values is 24-28mmol/L.
What does the base deficit/base excess value indicate in ABG values?
The base deficit/base excess value describes whether the body’s buffers are being consumed (deficit) or retained (excess). The normal range is +2 to -2mmol/L.
What does the PaO2 value indicate in ABG values?
The PaO2 value outlines the level of oxygenation, taking into account the FiO2 (fraction of inspired oxygen). The normal range is 10-14kPa.
What does the anion gap value measure in ABG values?
The anion gap value measures the difference between the concentration of cations and anions in plasma. The normal range is 10-15mmol/L.
What is the role of the respiratory mechanism in acid-base balance?
The respiratory mechanism is a rapid response system that transfers carbon dioxide from pulmonary venous blood to alveolar gas for excretion. Dysfunction in respiration can lead to retention or overexcretion of carbon dioxide and affect hydrogen ion concentration, leading to respiratory acidosis or respiratory alkalosis.
What does the serum lactate value reflect in ABG values?
The serum lactate value primarily reflects the extent of anaerobic metabolism occurring within the body and secondarily reflects the liver’s ability to metabolize lactate and regenerate bicarbonate anions. The normal range is <1.2mmol/L.
What is the role of the renal mechanism in acid-base balance?
The renal mechanism is a slower responding system that depends on the excretion of hydrogen ions in the urine by the distal nephron. Impairment in renal function can prevent the excretion of non-volatile hydrogen ions, resulting in metabolic acidosis.
What is the primary buffer for retained hydrogen ions in the body?
Proteins are the primary buffer for retained hydrogen ions in the body.
Which components of the carbon dioxide/bicarbonate system are measured in the blood to assess acid-base status?
The carbon dioxide tension and bicarbonate level in the blood are measured to assess the acid-base status of the body. These measurements reflect both the volatile and non-volatile arms of the system.
What is respiratory acidosis?
Respiratory acidosis occurs when there is a retention of carbon dioxide, leading to an increase in hydrogen ion concentration ([H+]) in the body.
How does the kidney respond to compensate for respiratory acidosis?
The kidney responds to respiratory acidosis by increasing the excretion of hydrogen ions in the distal nephron over a period of approximately 48 hours. This helps return the hydrogen ion concentration ([H+]) towards normal, although complete normality may not be achieved.
What causes metabolic acidosis?
Metabolic acidosis can be caused by the inability of the kidney to excrete non-volatile hydrogen ions or by a sudden increase in non-volatile acid load, such as in sepsis. This drives the acid-base equation to the right, and the respiratory system rapidly responds by increasing minute volume, reducing carbon dioxide (CO2), and returning the hydrogen ion concentration ([H+]) towards normal.
What is respiratory alkalosis?
Respiratory alkalosis occurs when the minute ventilation is higher than necessary to maintain the appropriate PaCO2 (partial pressure of carbon dioxide) for a hydrogen ion concentration ([H+]) of 40 nmol/L. This leads to a decrease in PaCO2 and a decrease in the hydrogen ion concentration ([H+]), resulting in a rise in pH.
What can cause respiratory alkalosis?
Respiratory alkalosis is commonly caused by an increased central respiratory drive, which can be due to factors such as fever, hepatic disease, aspirin toxicity, or CNS dysfunction.
What is metabolic alkalosis?
Metabolic alkalosis occurs when the level of bicarbonate in the blood increases due to abnormal retention or administration of bicarbonate or the loss of non-volatile acid from the body. It can also be associated with chloride depletion due to loop diuretics or chronic hypokalemia.
How can the acid-base status of a patient be determined?
The acid-base status of a patient can be determined by knowing the hydrogen ion concentration ([H+]/pH), PaCO2, and bicarbonate levels. These values help identify the type of abnormality and estimate the degree of compensation.
What is the standardised bicarbonate value used for?
The standardised bicarbonate value corrects the measured bicarbonate level to the value that would be present if the PaCO2 was normal (40mmHg or 5.4kPa). It provides a more accurate assessment of the non-volatile acid-base state.
What does the calculated base excess represent?
The calculated base excess is a value that indicates the difference between the standardised bicarbonate and the normal value. It reflects the amount of acid or alkali needed to return the blood to normal pH under standard conditions.
What are some common causes of metabolic acidosis?
Common causes of metabolic acidosis include impaired tissue perfusion, renal failure, and hepatic failure. Treatment options may include addressing the cause, improving circulation/perfusion, using bicarbonate, or considering renal replacement therapy or transplantation.
What are some causes of respiratory acidosis?
Causes of respiratory acidosis include head or spinal injury, drug overdose, chest wall deformity or injury, myopathy or peripheral neuropathy, pulmonary disease, and massive pulmonary embolism. Treatment options may involve ventilation, specific antidotes, surgery, respiratory support, or re-establishing perfusion of the ventilated lung.
What information can be obtained from blood gases?
Blood gases provide important information for managing acid-base disturbances. The pH indicates whether there is acidosis or alkalosis, the base excess indicates whether the acidosis is metabolic(negative base excess) or respiratory, the PaO2 indicates the presence of hypoxia (to be interpreted with FiO2), and the PaCO2 and bicarbonate levels indicate respiratory acidosis. Additional information such as lactate, hemoglobin (Hb), sodium (Na+), potassium (K+), and glucose concentrations may also be helpful in emergency situations.
What is the role of National Early Warning Scores (NEWS)?
National Early Warning Scores (NEWS) play a vital role in detecting derangements in cardiovascular parameters and prompting medical review or planning of subsequent patient care. They help with prediction and prevention of complications.
What is the first step in interpreting blood gases?
The first step is to look at the pH and determine if the patient is acidotic, alkalotic, or if the pH is normal.
How can respiratory acidosis or alkalosis be identified?
To identify respiratory acidosis, look at the PaCO2 (partial pressure of carbon dioxide). If the PaCO2 is high, it indicates respiratory acidosis. If the PaCO2 is low, it suggests respiratory alkalosis or a compensated metabolic acidosis.
How can metabolic acidosis or alkalosis be identified?
To identify metabolic acidosis, look at the standard HCO3 (bicarbonate) level. If the HCO3 is low, it indicates metabolic acidosis or a compensated respiratory alkalosis. If the HCO3 is high, it suggests metabolic alkalosis or a compensated respiratory acidosis.
How can the primary abnormality be determined?
The direction of H+ change often indicates the primary abnormality. The nature of the primary abnormality can be determined by considering the clinical context.
What should be considered when interpreting blood gases?
In addition to pH, PaCO2, and HCO3, it is important to look at other variables such as lactate, potassium (K+), calcium (Ca2+), and hemoglobin (Hb). The higher the lactate level, the greater the concern. Evaluating these variables provides a comprehensive understanding of the patient’s condition.
What does collapsed neck veins indicate in relation to CVP?
Collapsed neck veins with the patient at a 45° angle indicate a likely low CVP.
When might formal CVP monitoring be needed?
Formal CVP monitoring may be needed to manage patients where further fluid management is becoming problematic, such as when the patient’s blood pressure is not responding to several fluid challenges and there is no bleeding.
What does the visibility of the internal jugular vein indicate?
If the internal jugular vein is not visible with the patient lying flat, it is always abnormal.
What level should the haemoglobin be maintained at in stable patients with heart failure?
Around 80g/L
When should serial troponin levels be measured if infarction/ischaemia is suspected?
From 6 hours after the onset of symptoms
What can elevated troponin levels indicate other than cardiac ischaemia?
Elevated troponin levels can be seen in patients with sepsis or other cardiorespiratory pathologies, such as acute heart failure or pneumonia.
What determines the appearance of the QRS complexes in different leads?
The rotation of the heart determines the appearance of the QRS complexes in different leads.
Why does the size of the R wave increase progressively from V1 to V6?
The size of the R wave increases progressively from V1 to V6 because the underlying myocardium becomes thicker over the left ventricle.
What can cause the R wave in V6 to be smaller than that in V5, and the R wave in V5 to be smaller than that in V4?
The R wave in V6 may be smaller than that in V5, and the R wave in V5 may be smaller than that in V4 if the electrodes in these leads are further away from the myocardium.
How does the size of the S wave change towards V6?
The size of the S wave tends to decrease towards V6.
What causes the direction of the QRS complex to change from positive to negative?
The direction of the QRS complex changes from positive to negative as it progresses from V1 to V6 due to the rotation of the heart about a near-vertical axis.
What can cause abnormally large R waves and S waves?
Abnormally large R waves and S waves can be caused by conditions producing hypertrophy, such as left ventricular hypertrophy secondary to hypertension or aortic valve disease.
What produces “vector loops” of electrical activity in the heart?
The spread of depolarisation across the myocardium produces “vector loops” of electrical activity.
Can thin patients have “abnormally” high R waves?
Yes, in thin patients, the R wave may be “abnormally” high over V4 to V6.
How can the “angles” at which the heart is observed be displayed?
The “angles” at which the heart is observed can be displayed using the hexaxial reference system.
How does the angle of the electrical wave in relation to an electrode affect the deflection recorded?
The angle of the electrical wave in relation to an electrode determines the degree of upward or downward deflection recorded by it.
What defines a wide QRS complex?
A wide QRS complex is defined as being greater than 0.12 seconds.
What is the electrical axis range?
The electrical axis ranges from +90° to -30°.
What is the vertical range of the electrical axis?
The vertical range of the electrical axis is +60° to +90°, which is observed in tall individuals.
What is the normal width of the QRS complex?
The normal width of the QRS complex is less than 0.12 seconds.
What is the intermediate range of the electrical axis?
The intermediate range of the electrical axis is +30° to +60°.
What is the normal orientation of the T wave?
The T wave is normally upright, except in the aVR lead. Inversion can also occur in leads III, V1, and V2.
What is the horizontal range of the electrical axis?
The horizontal range of the electrical axis is +30° to -30°, which is observed in stocky, squat individuals.
What can cause tall, peaked P waves?
Tall, peaked P waves can be seen in pulmonary hypertension (referred to as “pulmonary P”).
What can cause biphasic P waves?
Biphasic P waves can be seen in mitral valve disease (referred to as “mitral P”).
What is the normal orientation of the P wave?
The P wave is normally upright. Inversion can occur in retrograde P waves in atrioventricular nodal rhythm.
How is the PR interval measured?
The PR interval is measured from the start of the P wave to the first deflection of the QRS complex, regardless of its orientation.
Which leads have a normal Q wave?
A normal Q wave can be seen in lead III, aVR, and sometimes in V4, V5, and V6.
What is the normal range for the PR interval?
The normal range for the PR interval is 0.12 to 0.2 seconds.
When is the U wave normal?
The U wave is normal when the T wave is normal, but in hypokalemia, it may become more prominent as the T wave flattens.
What are the criteria for a normal Q wave?
A normal Q wave should have a duration of no more than 0.04 seconds and a depth no more than one-quarter the height of the following R wave.
What should be ruled out or corrected in the diagnosis and management of hypotension?
Hypovolemia, hypoxia, hypokalemia, and hypomagnesemia
What should be checked in the diagnosis and management of tachyarrhythmias?
Routine medications
What is the commonest cardiovascular problem seen in unwell surgical patients?
Hypotension
What can be done to correct a supraventricular tachycardia temporarily?
Valsalva maneuvers
When can cardioversion be considered?
Cardioversion can be considered when there is a very rapid rate or evidence of compromise, particularly in the case of ventricular tachyarrhythmias.
How can supraventricular tachycardia (SVT) be temporarily controlled?
Intense vagal stimulation (e.g., Valsalva maneuver) or administration of adenosine
What is the recommended management for ventricular tachycardias (VTs)?
Prompt specialist referral and cardioversion if necessary
What effect does adenosine have on the atrioventricular (AV) node?
It has a powerful blocking effect, slowing ventricular rate if the dysrhythmia is atrial in origin
How can ventricular ectopics (VEs) be distinguished from other causes of an irregular pulse?
By performing an ECG
What precautions should be taken when using adenosine?
Avoid use in asthmatic patients and in the presence of dipyridamole
When should treatment be considered for ventricular ectopics?
If the ratio of VE to normal QRS is greater than 1:6 or if VEs are multifocal
What is the danger associated with ventricular ectopics?
The possibility of ventricular fibrillation, especially if an ectopic arises on the apex of a T wave (R on T phenomenon)
What other underlying problems may be indicated by the development of new ventricular ectopics?
Sepsis, electrolyte disturbance, valvular heart disease, cardiomyopathies, hypoxia, or digitalis toxicity
What is sinus tachycardia?
Regular heart rate, up to 160 bpm in young patients, gradual onset, normal P wave and morphology
What are some possible causes of sinus tachycardia?
Hypovolemia, anemia, pulmonary embolism, sepsis, etc.
What is paroxysmal supraventricular tachycardia (SVT)?
Any tachycardia originating in the AV node, atria, or sinoatrial (SA) node
What are the characteristics of paroxysmal SVT?
Regular heart rate (150-250 bpm), abnormal P waves (may or may not be seen), usually normal QRS width
What are the treatment options for paroxysmal SVT?
Verapamil, digoxin, or beta-blockade (avoid combining beta-blockers with verapamil)
How can paroxysmal SVT be abolished or slowed?
By using adenosine
What is atrial fibrillation (AF)?
Irregularly irregular heart rate, variable ventricular rate (often 100-180 bpm)
What are some common causes of atrial fibrillation?
Postoperative state, hypovolemia, hypoxia, electrolyte disorders, cardiopulmonary disease
What is the management approach for new cases of atrial fibrillation?
Identify and correct underlying factors, treat any associated problems, seek expert help if needed
When is urgent treatment needed for atrial fibrillation?
When serious adverse signs are present (e.g., hypotension, shock, chest pain, heart failure, decreased conscious level, or marked tachycardia >140 bpm)
What are the treatment options for urgent management of atrial fibrillation?
DC cardioversion or intravenous amiodarone, seek expert help immediately
How is long-standing atrial fibrillation usually treated?
With digoxin or amiodarone, seek expert help if problems persist or recur
What is atrial flutter?
Regular flutter P waves at 300/min, normal QRS with variable AV block, usually associated with cardiac disease
How can atrial flutter be diagnosed and treated?
Diagnosis: presence of flutter waves or response to adenosine; Treatment: cardioversion, digoxin, or verapamil
What are the clinical associations of left ventricular hypertrophy?
Conditions causing an increase in afterload or work on the left ventricle, such as aortic valve disease and systemic hypertension
What are the ECG findings of left ventricular hypertrophy?
Tall R waves in leads I and aVL, deep S waves in leads III and aVF, tall R waves in leads V4 to V6, deep S waves in leads V1 to V3
What are the clinical associations of right ventricular hypertrophy?
Conditions causing increased right ventricular afterload, such as pulmonary hypertension, cor pulmonale, and pulmonary stenosis
What are the ECG findings of right ventricular hypertrophy?
Right-axis deviation in leads I, II, and III, tall R wave in lead V1, deep S wave in lead V6, tall pulmonary P wave suggesting right atrial hypertrophy
What are the ECG findings of left bundle branch block?
Delayed electrical activity in the left ventricle, resulting in an “M”-shaped QRS wave in leads V5, V6, I, and aVL, and a “W”-shaped QRS in leads III and aVF
What are the ECG findings of right bundle branch block?
Right ventricular depolarization occurs via the left ventricle, resulting in an “M”-shaped QRS wave in leads V1, V2, and V3
What clinical associations are associated with right bundle branch block?
Coronary artery disease, valvular heart disease, ventricular hypertrophy and fibrosis, and cardiomyopathies
What are the treatment options for symptomatic bradycardia?
Atropine (0.6-1.2mg) or pacing; Isoprenaline infusion under guidance of an intensivist or cardiologist
What are some autonomic conditions associated with bradycardia?
Pain, especially visceral pain (may also be associated with tachycardia), raised intracranial pressure, β-blocker drugs, epidural
What are some non-autonomic conditions associated with bradycardia?
Myocardial infarction (particularly inferior MI), sepsis, hypoxia, drugs (digitalis toxicity), hypothyroidism, hypothermia
What is the recommended approach for patients with a recent MI (within the previous 6 months) who require elective surgery?
Delay elective surgery if possible, as the incidence of perioperative MI is higher during this period
What should be done with cardiac drugs for patients undergoing surgery?
They should be continued up to and including the day of operation and recommenced postoperatively, with consideration for antiplatelet medication if a coronary vessel stent has been inserted
What are the possible presentations of perioperative MI?
Shortness of breath, hypotension, evidence of decreased organ function, acute dysrhythmias, sudden pulmonary edema, cardiac arrest, and acute upper abdominal pain
What ECG changes may indicate an MI?
ST-segment elevation of >1mm in relevant leads, inversion in leads opposite to the infarct, flattening and inversion of T waves, and development of Q waves over time
What treatment options are available for MI?
Percutaneous coronary intervention or clot thrombolysis, which should be decided by a cardiologist
What initial measures should be taken when suspecting an MI?
Check and correct ABCDEs, provide suitable analgesia, administer high-flow oxygen, give glyceryl trinitrate to reduce coronary artery spasm, consider aspirin, and address conditions that can exacerbate myocardial hypoperfusion
What investigations should be arranged for a suspected MI?
Serial ECGs and blood tests to exclude anemia, electrolyte disturbances, and measure troponin levels
What are the ECG findings for inferior myocardial infarction?
Raised ST segments and Q waves in leads II, III, and aVF, with reciprocal ST depression in leads I, aVL, and V2-V4. Non-pathological Q waves may also be present.
What are the ECG findings for anterior myocardial infarction?
Raised ST segments in V1-V4
What factors should be considered in the acute treatment of myocardial infarction with ST segment elevation?
Local resources, risks of bleeding versus benefits of intervention, anticoagulation, anti-platelet treatment, and discussion with the surgical team
What is the recommended acute treatment for myocardial infarction with ST segment elevation according to NICE Guideline CG167?
(i) Aspirin, (ii) primary percutaneous intervention followed by anticoagulation or thrombolysis, (iii) glycoprotein IIb/3a inhibitors, (iv) glycaemic control, and (v) β-blockers
What are the contraindications to fibrinolytic therapy for myocardial infarction?
Active peptic ulcer, previous haemorrhagic stroke, recent head injury (even minor), and prolonged traumatic CPR
What secondary therapies should be considered for myocardial infarction once the patient is haemodynamically stable?
Angiotensin-converting enzyme (ACE) inhibitor and a statin therapy
What are the different types of acute myocardial infarction included in acute coronary syndromes?
Transmural myocardial infarction, Q-wave myocardial infarction, and ST elevation myocardial infarction (STEMI)
What does the term “acute coronary syndrome” encompass?
It refers to a variety of myocardial conditions, including acute myocardial infarction (both Q wave and non-Q wave) and unstable angina
What are the different types of non-Q-wave myocardial infarction included in acute coronary syndromes?
Sub-endocardial infarction and non-ST elevation myocardial infarction (non-STEMI)
What is the most common cause of acute coronary syndromes?
Rupture or erosion of an atherosclerotic plaque in a coronary artery, leading to thrombus formation
What is unstable angina?
It is a type of acute coronary syndrome characterized by chest pain that occurs at rest or with minimal exertion
What are the treatment strategies for acute coronary syndromes?
Institution of treatment by the cardiology team, consideration of aspirin, other antiplatelets (e.g., clopidogrel), anticoagulation, glycaemic control, and β-blockade
What should be measured to assess acute coronary syndromes?
Serial troponin levels
What are the different levels of severity in cardiac failure?
From mild dyspnoea to cardiogenic shock
What are the factors that affect cardiac function?
Preload, intrinsic myocardial function, and afterload
What is intrinsic myocardial function?
It refers to the function of the cardiac muscle itself
What conditions can affect afterload?
Conditions that alter circulatory resistance or cause an obstruction to flow
How can afterload be understood?
It can be thought of as the work demanded of the heart to overcome resistance to forward flow
What are some causes of cardiac failure in surgical critical care?
Hypovolemia, fluid overload, pneumothorax/cardiac tamponade, ischemia, infarction, dysrhythmias, chronic heart failure with operative stress, electrolyte disturbances, myocardial depressant factors, aortic/pulmonary valvular stenosis, pulmonary embolism, and aortic dissection
What are the steps in the acute management of heart failure?
Assess and treat ABCDEs, give oxygen and monitor SaO2, stop IV infusions (temporarily if necessary), consider diuretics, nitrates, and diamorphine, perform a 12-lead ECG, treat any underlying cause, consider CPAP if no improvement, monitor CVP, and consider early specialist referral
How is cardiogenic shock defined?
Severe impairment of cardiac function with hypotension of less than 90mmHg or 30mmHg less than the patient’s “normal” systolic pressure
What is the most common cause of cardiogenic shock?
Severe myocardial ischemia or infarction
Which type of surgery carries a higher risk of perioperative MI?
Abdominal and thoracic surgery
What happens in the body during cardiogenic shock?
Cardiac output falls, systemic hypotension occurs, organ perfusion decreases, left ventricular end-diastolic pressure rises, pulmonary venous pressure increases, leading to pulmonary edema formation
What are the risk factors for cardiac disease in non-cardiac surgery?
Recent MI (within 6 months), unstable angina, severe aortic stenosis, decompensated heart failure, severe hypertension, cardiac arrhythmias
What are some potential side effects of antihypertensive drugs?
Hypokalemia (diuretics), hyperkalemia (ACE inhibitors), impaired responses to hypovolemia (vasodilators and β-blockers)
When should cardiology be involved in cases of acute, life-threatening hypertension?
When the blood pressure remains at 220/120mmHg or above with signs of organ dysfunction
What is the estimated chance of re-infarction based on the timing of a recent MI?
60% within 3 weeks, 27% within 3 months, 11% within 3-6 months
What are the different types of pacemakers?
Simple fixed-rate type (rarely used), complex demand type with or without internal defibrillators
How can the use of diathermy affect pacemakers?
Diathermy can inhibit the demand type pacemakers, but it is less likely to cause problems with a standard fixed-rate type
What precautions should be taken when a patient with a pacemaker requires surgery?
Ensure recent cardiology review, consider switching off internal defibrillator function, place diathermy earthing pad away from the pacemaker, use short bursts of diathermy, prefer bipolar diathermy, avoid using diathermy near the pacemaker, monitor ECG during the procedure
How is shock characterized?
Shock is characterized by an acute alteration of circulation leading to inadequate perfusion, cellular damage, dysfunction, and failure of major organ systems.
What is the importance of blood flow distribution in the shocked state?
In the shocked state, the distribution of blood flow is important. Some organs can preserve flow through autoregulation (brain, heart, kidney), while others cannot (gut, skin), resulting in hypoperfusion of certain organs to maintain perfusion integrity in other organs.
What is the common pathway for the initiation of systemic inflammation in shock?
Intestinal hypoperfusion, even with normal blood pressure and pulse, can lead to a prolonged period of intestinal hypoxia, cytokine generation, and initiation of a mediator response that results in the onset of systemic inflammation.
What are the four principal categories of shock based on etiology?
Hypovolaemic, cardiogenic, obstructive, and vasodilatory (or apparent hypovolaemia) shock.
What are some common mechanisms of shock?
Hypovolaemia (hemorrhage, fluid loss, dehydration), cardiogenic (MI, heart failure, arrhythmia), obstructive (PE, cardiac tamponade, pneumothorax), and vasodilatory (sepsis, neurogenic, anaphylaxis, adrenal insufficiency).
What is the relationship between stroke volume and ventricular filling pressure?
Stroke volume is directly linked to ventricular filling pressure by the Frank-Starling curve.
How can the Frank-Starling curve be influenced?
The curve can be shifted up and to the left (improved cardiac contractility for the same degree of filling) by using inotropic drugs and sympathetic stimulation.
What is the direct cause of low cardiac output in hypovolaemic shock?
The low cardiac output in hypovolaemic shock is a direct reflection of reduced venous return (preload).
How is haemorrhage classified in terms of volume loss?
Haemorrhage is classified into four stages based on the degree of blood loss: stage 1 (<750ml), stage 2 (750-1500ml), stage 3 (1500-2000ml), and stage 4 (>2000ml). However, this classification has limited clinical usefulness as the signs of haemorrhagic shock do not directly correlate with the degree of shock.
What are some iatrogenic surgical factors that can contribute to hypovolaemia?
Iatrogenic surgical factors that can contribute to hypovolaemia include poor fluid prescription, slow or tissued intravenous infusion, inappropriate use of diuretics, mechanical bowel preparation, fasting prior to anesthesia, and ongoing fluid losses during prolonged operations and from dissected areas after surgery.
What are some causes of primary impairment of cardiac function in cardiogenic shock?
Primary impairment of cardiac function in cardiogenic shock can result from myocardial infarction or ischemia, acute arrhythmias, acute cardiomyopathy, acute valvular lesions (caused by aortic dissection or trauma), or myocardial contusion.
What are the effects of true neurogenic shock on venous return and cardiac output?
True neurogenic shock leads to reduced venous return and reduced cardiac output due to the rapid increase in size of the vascular bed, including venous capacitance vessels.
What causes true neurogenic shock?
True neurogenic shock occurs following spinal transection or brainstem injury, resulting in loss of sympathetic outflow below the level of injury and subsequent vasodilation.
What mediates anaphylactic reactions and what are the resulting effects?
Anaphylactic reactions are mediated by IgE antibodies, resulting in massive degranulation of mast cells. This leads to histamine and serotonin release, systemic kinin activation, rapid vasodilation, a fall in systemic vascular resistance (SVR), hypotension, severe bronchospasm with hypoxia and hypercarbia.
How does adrenal failure contribute to shock?
Adrenal failure, characterized by the sudden withdrawal of circulating cortisol and aldosterone, can be a potent cause of shock.
What is the recommended treatment for anaphylaxis?
Prompt treatment for anaphylaxis includes administration of oxygen, fluids, adrenaline, hydrocortisone, and an antihistamine. Additionally, removal and subsequent avoidance of the trigger substance are necessary.
How does the fall in SVR in anaphylaxis differ from sepsis?
In anaphylaxis, the fall in SVR is sudden and profound, causing a marked decrease in blood pressure.
When does acute adrenal failure commonly occur?
Acute adrenal failure commonly occurs in severe sepsis, specifically in cases of Waterhouse-Friderichsen syndrome, usually of meningoccal origin.
When is adrenal insufficiency often seen?
Adrenal insufficiency, often subacute, is seen in patients who have omitted necessary perioperative steroid cover or in cases of severe sepsis requiring high levels of pressor and inotropic support.
What additional treatment may be needed for patients with adrenal insufficiency?
Patients with adrenal insufficiency may require additional doses of steroids, such as 50mg hydrocortisone four times a day (QDS).
What causes septic shock?
Septic shock occurs when a patient becomes hypotensive and tissues are inadequately perfused due to organisms, toxins, or inflammatory mediators resulting from sepsis. Common sources of sepsis include the abdomen, chest, soft tissues, wounds, urine, and intravascular lines or other medical implants.
