Therapeutic Handbook - GGC Prescribing

CPAP in cardiogenic pulmonary oedemaCardiovascular System• Continuous positive airway pressure (CPAP) can be considered in patients who have notresponded to medical treatment. However, discuss this option with a senior.• CPAP increases intrathoracic pressure, which reduces preload by decreasing venous return.• CPAP lowers afterload by increasing the pressure gradient between the left ventricle and theextrathoracic arteries, which may contribute to the associated increase in stroke volume.• Intubation should be considered in patients with persistent hypoxaemia on CPAP or persistenthypercapnia despite the administration of oxygen, morphine, diuretics, and vasodilators. Inaddition, intubation is required in the setting of apnoea or profound respiratory depression(respiratory rate < 10 bpm).Contraindications to CPAP:• Reduced conscious level (not responding to pain or unconscious on the AVPU scale: unable toprotect airway therefore consider invasive ventilation)• Dementia resulting in intolerance of therapy• Systolic blood pressure < 90 mmHg• Pneumothorax• Facial trauma / base of skull fracture• Type II respiratory failure / severe emphysemaComplications of CPAP:• Hypotension – CPAP increases mean intrathoracic pressure, reducing systemic venous returnand cardiac output• Aspiration – gastric contents may be aspirated due to large volumes of air being blown into thestomach• Gastric distension – large volumes of air swallowed can overcome resistance of loweroesophageal sphincter• Anxiety – hypoxia and tight fitting mask can induce anxiety and panicWhen to stop CPAP:Continue CPAP until chest clear of rales and haemodynamically stable. Initially wean airway pressurethen wean supplemental oxygen and change to standard facemask.If there has been no clinical improvement after 30 minutes, CPAP should be stopped.Continues on next pagePage 114