Incidence and magnitude of hypoxaemia with ketamine in a rural African hospital.

The incidence of hypoxaemia with ketamine anaesthesia in unpremedicated, spontaneously breathing patients without oxygen supplementation at high altitudes has never been investigated. Twenty-three consenting patients received ketamine (2 mg.kg-1 intravenously in adults or 8 mg.kg-1 intramuscularly in children supplemented with 0.5 mg.kg-1 intravenously when clinically indicated) as the sole anaesthetic agent in a small, rural hospital in central Kenya (altitude 6000 ft; PIO2 127 mmHg). Oxygen saturation (SpO2) was measured with pulse oximetry. The SpO2 values were grouped in time epochs of pre-induction, postinduction but presurgery, every 1-2 min after start of surgery, and at the end of the case. The mean SpO2 values reached 90.8% during the first min following start of surgery and this was significantly different from pre-induction levels (p < 0.01). In four patients (17%) SpO2 decreased to 90% or less, in two patients (9%) SpO2 decreased to 85% or less, and in two patients (9%) SpO2 decreased to 75% or less. Mean values returned to near baseline by the end of the surgery. It is concluded that ketamine anaesthesia is acceptable in this setting if monitored by vigilant personnel who are capable of providing supplemental oxygen (if available) and manual support of the airway (i.e. jaw thrust) if airway obstruction occurs.