Respiratory Compromise Flashcards
O2 failure
@PaO2 <8 kPa rapid desaturation
Type 1 - Failure to OXYGENATE - so normal or reduced PaCO2
Type 2 - Failure to VENTILATE –> hypoxia and hypercarbia
Type 2 may be acute or may have chronic - look at Bicarb
Surgical resp failure
Acute fall in FRC without pulmonary vascular dysfunction
- Mechanics after trauma (non-compliant)
- Acute postoperative atelectasis, sputum retention, pneumonia, depression of respiration
Acute fall in FRC with pulmonary vascular dysfunction –> left ventricular failure, fluid overload, pulmonary HTN, PE, neurogenic pulmonary oedema, ARDS
Airflow obstruction - COPD, asthma, airflow obstruction
Risk factors
Pre-existing disease Obesity Smoking Thoracic surgery Upper abdominal surgery Older age
Signs
Dyspnoea, tachypnoea, apnoiec Unable to speak in sentences Accessory muscles Cyanosed Sweating and tachycardia Exhibiting decreased LOC
Hypoxia kills before hypercarbia
Pulse oximetry
Detects pulsatile flow plethysmographically
Differentiates between oxygenated and reduced Hb through light absorption
Saturation does not equate to the partial pressure of oxygen
Delay of 20 seconds usually
Does not detect hypercarbia or acidosis
Carboxyhaemoglobin can cause erroneous readings
Other factors: movement, peripheral vasoconstriction, arrhythmia, profound anaemia, SaO2 below 70, diathermy, bright lights, dirty skin, nail varnish
Chest x-ray findings
Air bronchogram - oedema, infection, or other infiltrates
Kerley B - fluid or tissue within intralobular septa
Bronchitis/emphysema - increased lucency, general loss of vascularity, increase in lung field size
Management of respiratory failure and compromise
mask up to 0.6 FiO2
Needs to be humidified –> otherwise thickens secretions
Treat the cause of respiratory failure
If sputum clearance primary problem –> NP airway / cough assist machine should be used
Failure of mask therapy –> respiratory rate, distress, dyspnoea, exhaustion, sweating and confusion, O2 saturation less than 80%, PaO2 less than 8, PaCO2 greater than 7
Anticipate problems in severe chronic lung disease
VC < 15mL/kg, or FEV1 <10mL/kg
CPAP
Used for Type 1
Can range from 2.5 –> 10cmH2O
Because pressure cannot drop below pressure that you place it on –> recruitment one under ventilated alveolar, increases FRC, decreases intrapulmonary shunt and the work of breathing and may improve oxygenation
Need to consider the PEEP from CPAP and any upper GI surgery / ENT
Signs that not tolerating CPAP = refractory hyperaemia, increasing RR, progressively smaller tribal volumes, with subsequent CO2 retention, or in toleration / agitation / obtundation
NIV by mask (BiPAP)
Two pressures are applied –> higher one during inspiration and a lower one in expiration usually 20/5
The pressure differences generates gas flow into the lungs during inspiration
Tidal volume determined by lung compliance, duration of inspiration, driving pressure
Contraindications - CV unstable, ALOC, severe metabolic acidosis, poor respiratory rate
NG tube to reduce gas distension
Ventilation
Can give O2 up to concentrations of 100%
Can mechanically breathe
Can adjust Vt
The greater the minute volume the greater the removal of CO2
Usually Vt should be 6mL per kg of predicted body weight
Controlling Vt may improve outcomes in patients undergoing intra-abdominal procedures
HiFlow has PEEP of 5
Use SIMV to preserve some of respiratory muscle activity
Controlled mandatory ventilation not used much and that’s where no SIMV
SIMV with pressure controlled ventilation or pressure support ventilation and PEEP
PSV alongside PEEP may be ushered once patient has achieved a good respiratory rate and pattern
Only need to paralyse the most difficult to ventilate patients
High peak airway pressure can affect venous return and also predisposes to barotrauma
Toxic effects of oxygen as well
Permissive hypercapnia essentially used to reduce barotrauma
PCIRV is pressure controlled inverse ratio ventilation
Proning
Redistributes blood flow to less consolidated or collapsed, more easily ventilated, anterior portions of lung
Weaning from ventilatory support
Contraindications - originally cause has been treated successfully, sedative drugs reduced to a level where respiratory not depressed, low inspired O2 concentration maintains normal PaO2, CO2 elimination no longer a problem, sputum production is minimal, nutritional status, minerals and trace elements are normal, NM function of diaphragm and intercostals is adequate, patient is reasonably cooperative
PCV –> SIMV –> ASB/PSV –> CPAP and T piece –> extubation
Atelectasis
Atelectasis - reduced expansion
Can be due to pain etc. and is exacerbated in elderly, overweight, smokers and those with pre-existing disease
Avoiding unnecessarily high FiO2 and good tidal volumes
Symptoms - cough, chest pain, dyspnoea, low O2 saturations, pleural effusion, cyanosis, tachycardia
May be benefit of early use of high flow
Pneumonia
Causes parenchymal or alveolar inflammation and abnormal filling of alveoli with fluid (consolidation and exudation)
Symptoms of pneumonia include cough, chest pain, fever, dyspnoea
