Intra-operative Flashcards
Safety - Nil by mouth policy: explain the principles of nil by mouth policy before surgery
- No food 6hr before surgery
- No water 2hr before surgery
Reduces aspiration risk
Caveats - reflux, obesity, slow gastric transit time
Safety - Transfusion reporting: recognise the importance of reporting blood units administered to the transfusion lab
- 6ml of blood is required for group and save - pink top vacutainer. Should be performed no more than 7 days in advance of actual transfusion (3days if pregnant)
- Blood products should only be removed from blood bank when you are ready to start the transfusion - blood is stored at 4oC
- Bedside check - tag&bag, tag& pt wristband. Stickers from blood tag must be signed by 2 medical professionals to check who identity was confirmed by - this tag is then returned to the blood bank.#
- 20G cannula is the minimum size required; 170-200 micron filter is required with the giving set
Safety - Controlled drugs: recognise the importance of recording the use of controlled drugs in the controlled drug register
- Dose
- Form
- Strength (if appropriate)
- total quantity/dosage units in words and figures
- If instalment prescription, specify instalment amount and interval
Airway adjuncts/devices: recognise various airway adjuncts/devices and the indications for their use
Bag valve mask - Ambu bag - FiO2 (fraction of inspired oxygen in the air, is thus 21%), self inflating bag, has a reservoir bag at the end for when giving O2
Oropharyngeal airways - Guedel airways - angle of mandible to mouth edge size: green (2), orange (3), red (4)
Supraglottic airways - iGel/LMA (largyngeal mask airway)
endotracheal tubes - blue line is X-Ray
Laryngoscope
- Macintosh blade
- Sizes 0 (neonate) to 4
- Held with left hand
- Incorrect usage can cause trauma to the front incisors; the correct technique is to displace the chin upwards and forward at the same time, not to use the blade as a lever with the teeth serving as the fulcrum.
- Alternative: video laryngoscope (GlideScope)
Bag-valve mask
- FiO2 unless connected to oxygen at the wall
- Has a reservoir bag which can inflate with oxygen when bagging the patient
- Uses: emergencies, positive pressure ventilation in patients in and out of hospital
Endotracheal tube
Name: ET
Uses: definitive airway
- Provides optimal control of the airway once cuff inflated
- May be used for long or short term ventilation
- Errors in insertion may result in oesophageal intubation (therefore end tidal CO2 usually measured)
- Paralysis often required
- Higher ventilation pressures can be used
- ET should be inserted to an average depth of 23 cm in men and 21 cm in women (measured at the incisor).
Tracheostomy
- Reduces the work of breathing (and dead space)
- May be useful in slow weaning
- Percutaneous tracheostomy widely used in ITU
- Dries secretions, humidified air usually required
Laryngeal mask airway (supraglottic airway)
- Widely used
- Very easy to insert
- Device sits in pharynx and aligns to cover the airway
- Poor control against reflux of gastric contents
- Paralysis not usually required
- Commonly used for wide range of anaesthetic uses, especially in day surgery
- Not suitable for high pressure ventilation (small amount of PEEP often possible)
Oropharyngeal airway
- Easy to insert and use
- No paralysis required
- Ideal for very short procedures
- Most often used as bridge to more definitive airway
- Flange at the buccal end stops it moving deeper into airway
Guedel sizing- angle of mandible to mouth edge
size: green-2 /orange-3/red-4
Respiratory - Ventilation: compare the differences between spontaneous ventilation and positive pressure ventilation
For air to enter the lungs, a pressure gradient must exist between the airway and the alveoli. This can be accomplished either by raising pressure at the airway (positive-pressure ventilation) or by lowering pressure at the level of the alveolus (negative-pressure ventilation).
Spontaneous ventilation - e.g. CPAP, BiPAP - every breath is spontaneous (patient triggered). Movement of gas in and out of a pt’s lungs in response to their respiratory muscles.
Positive-pressure ventilation can be achieved via an endotracheal or tracheostomy tube or noninvasively through a nasal mask or face mask.
- PEEP is used as an adjunct to ventilation. It is produced by maintaining a positive airway pressure during expiration, usually of the order of 5-20 cmH2O. It minimises airway and alveolar collapse and increases compliance (due to increase in FRC).
- PSV - pressure support ventilation - ventilatory assistance occurs only in response to the patient’s spontaneous inspiratory efforts. With each inspiratory effort, the ventilator raises airway pressure by a preset amount.
- IMV - intermittent mandatory ventilation - mandatory breaths are delivered at a set frequency, TV, and inspiratory flow rate. But patient can breathe spontaneously between machine controlled breaths. Most modern ventilators are capable of SIMV (synchronised IMV) where ventilator attempts to deliver the mandatory breaths in synchrony with the patient’s own inspiratory efforts.
- MMV - mandatory minute ventilation
Respiratory - Anaesthetic emergencies: recall the assessment and management of asthma.
Management of severe bronchospasm outside of theatre: - OSHITM
- A,B,C
- O2 -Start high flow oxygen and gain IV access
- Salbutamol nebulised 2.5-5mg
- Hydrocortisone 100 mg IV 6 hourly or prednisolone orally 40–50 mg/day.
- Ipatropium nebulised 0.5 mg (4–6 hrly) • IV salbutamol if not responding (250 mcg slow bolus then 5–20 mcg/min).
- Theophylline/Aminophylline
- Magnesium 2g IV over 20 minutes
- NB- In extremis (decreasing conscious level or exhaustion) adrenaline may be used: nebuliser 5 ml of 1 in 1,000;*
- Senior clinician only: IV 10 mcg (0.1 ml 1 : 10,000) increasing to 100 mcg (1 ml 1 : 10,000) depending on response.*
Respiratory - Anaesthetic emergencies: recall the assessment and management of pneumothorax.
- Definition - presense of air in the pleural cavity which leads to lung collapse. Can be life threatening if a tension pneumothorax develops and
- Presentation - in a ventilated pt there will be increased peak airway pressures and plateau pressures occur. As pneumothorax develops hypoxia, tachypnea and tachycardia can occur.
- Pathophysiology - one-way valve mechanism occurs after injury to the pleural space. with each inspiration, gas is trapped in the pleural space causing lung collapse. If intrapleural pressyre increases more then mediastinal shift can occur with kinking of major veins at thoracic inlet and IVC –> decreased venous return and hypotension.
- MANAGEMENT - increase FiO2 to 100%, decompress plwurl space with a large bore needle in the MCL in 2nd intercostal space, insert chest tube.
- DD - haemothorax, mucus plug, endobronchial intubation, severe bronchospasm.
- RF - central line placement, laparoscopic surgery and excessive tidal volumes or peak airway pressures, blebs.
Respiratory - Anaesthetic emergencies: recall the assessment and management of anaphylaxis.
ABCDE approach to anaphylaxis:
Airway problems:
- Airway swelling, e.g., throat and tongue swelling (pharyngeal/laryngeal oedema). The patient has difficulty in breathing and swallowing and feels that the throat is closing up.
- Hoarse voice.
- Stridor – this is a high-pitched inspiratory noise caused by upper airway obstruction.
Breathing problems:
- Shortness of breath – increased respiratory rate.
- Wheeze
- Patient becoming tired.
- Confusion caused by hypoxia.
- Cyanosis (appears blue) – this is usually a late sign.
- Respiratory arrest.
Circulation problems:
- Signs of shock – pale, clammy.
- Increased pulse rate (tachycardia).
- Low blood pressure (hypotension) – feeling faint (dizziness), collapse.
- Decreased conscious level or loss of consciousness.
- Anaphylaxis can cause myocardial ischaemia and ECG changes even in individuals with normal coronary arteries.
- Cardiac arrest.
What are the most common triggers for anaphylaxis?
Respiratory - Observations: recall the measurement and normal values of physiological parameters, including pulse oximetry, capnography and blood gas results
Pulse oximetry - measures SpO2 (although SaO2 would be more desirable, measures by arterial blood gases). Fingertip or earlobe. SaO2 is the percentage of Hb mols that are saturated with oxygen .
Capnography - monitors pCO2, measured as end-tidal (at the end of exhalation) so called ETCO2, good for assessing hypoventilation and oesophageal intubation. Usually shows an expiratory and inspiratory phase.
Blood gas results - VBG/ABG; see other notes.
Normal VBG and ABG results.
Circulation - Blood pressure monitoring: recall the indications for non-invasive and invasive monitoring (for and against invasive BP monitoring)
Invasive BP monitoring
Indications:
- More accurate especially in critically ill
- Rapid recognition of changes in BP (in those on vasoactive drugs)
- Frequent blood sampling - ABGs can be taken without injury
- Inability to use indirect monitoring (e.g. severe burns, morbid obesity)
Contraindications
- Absent pulse
- Burns over cannulation site
- Inadequate circulation to extremity
- Raynaud syndrome
- Buerger disease
- Also: anticoagulation, atherosclerosis, coagulopathy, inadequate collateral flow, infection at site.
Circulation - Intravenous fluids: explain the rationale of fluid administration
Hospitalised patients need fluids for one or more of the following:
Fluid resuscitation - to restore circulation to vital organs when there is loss of blood volume due to bleeding, plasm aloss of electrolyte loss (from GI tract).
Routine maintenance - when pt cannot meet their normal fluid or electrolyte needs by oral or enteral routes.
Replacement - to corrrct existing warer and/or electrolyte deficits or ongoing external losses e.g. fever or burns.
Redistribution - e.g. in those with sepsis where there is abnormal fluid handling.
What is the difference between colloid and crystalloid fluids?
Give crystalloid when there is decreased ISFV (interstitial fluid volume). Give colloid when there is decreased plasma volume (ISFV). Colloids give less volume, faster administration.
What is the composition of common IV fluids?
https://www.bapen.org.uk/pdfs/bapen_pubs/giftasup.pdf
Circulation - Blood transfusion: recall the triggers for giving a blood transfusion
Pain relief - WHO pain ladder: explain the WHO pain ladder
WHO three-step “ladder” for cancer pain relief in adults.
