Respiratory stimulants have a much reduced role in the management acute ventilatory failure, with the ready availability of mechanical methods for assisting respiration. Situations where they may still be encountered are:

• Acute exacerbations of chronic lung disease with hypercapnia, drowsiness and inability to cough or to tolerate low (24%) concentrations of inspired oxygen (air is 21% 02). A respiratory stimulant can arouse the patient enough to allow effective physiotherapy and, by stimulating respiration, can improve ventilation-perfusion matching. As a short-term measure, this may be used in conjunction with assisted ventilation without tracheal intubation (BIPAP4), and thereby 'buy time' for chemotherapy to control infection and avoid full tracheal intubation and mechanical ventilation

• Apnoea in premature infants; aminophylline and caffeine may benefit some cases.

Avoid respiratory stimulants in patients with epilepsy (risk of convulsions). Other relative contraindications include ischaemic heart disease, acute severe asthma ('status asthmaticus'), severe hypertension and thyrotoxicosis.

Irritant vapours, to be inhaled, have an analeptic effect in fainting, especially if it is psychogenic, e.g. aromatic solution of ammonia (Sal Volatile). No doubt they sometimes 'recall the exorbitant and deserting spirits to their proper stations'.5

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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