Ketamine Anesthesia at High Altitude

Abstract

There is a clinical need for a safe and effective anesthetic technique in high altitude and remote areas. This report presents a series of 11 consecutive cases documenting the use of ketamine anesthesia in a remote hospital at an altitude of 3,900 m, by primary-care physicians without specialist training in anesthesia. The method of administration is fully described. At a low dose of 2.0 mg/kg, ketamine produces a dissociative anesthesia that does not depress the hypoxic drive, or interfere with the pharyngeal or laryngeal reflexes. Although supplemental oxygen is useful in the recovery phase for less acclimatized individuals, it is usually not required as reductions in oxygen saturation can be raised by physical stimulation that encourages the patient to breathe faster and deeper. The common side effect of emergent nightmares was avoided using midazolam as premedication and a quiet recovery area. This study offers the first available evidence that ketamine with midazolam offers a safe and effective means of anaesthesia at very high altitude, without the need for specialist equipment or training, by careful clinicians experienced in basic airway management.

Ketamine for emergency anaesthesia at very high altitude (4243 m above sea‐level)*

“…Bishop et al reported a case series of 11 haemodynamically stable patients undergoing urgent surgery for trauma or local sepsis at Khunde Hospital, Nepal (3900 m above sea-level) [8]. Anaesthesia was administered by primary care physicians with no specialist training in anaesthesia.…”

“…Previous reports of ketamine anaesthesia at high (1500-3500 m above sea-level) or very high altitude (3500-5500 m above sea-level) [1] have involved elective or urgent cases who were haemodynamically stable [4][5][6][7][8].…”

Physiology and pathophysiology at high altitude: considerations for the anesthesiologist

“…Lowdose ketamine resulted in sustained apnea, possibly by central medullary chemoreceptor impairment, in one report [92]. Conversely, one small study of 11 patients at 3840 m found that low-dose ketamine (∼2.0 mg·kg −1 ) with midazolam produced dissociative anesthesia that did not depress the hypoxic respiratory drive significantly, nor did it interfere with the pharyngeal or laryngeal refl exes [93]. Supplemental O 2 had to be administered to 3 of these 11 patients when the O 2 saturation fell below 80% and was not corrected by a jaw thrust or stimulation [93].…”

“…Conversely, one small study of 11 patients at 3840 m found that low-dose ketamine (∼2.0 mg·kg −1 ) with midazolam produced dissociative anesthesia that did not depress the hypoxic respiratory drive significantly, nor did it interfere with the pharyngeal or laryngeal refl exes [93]. Supplemental O 2 had to be administered to 3 of these 11 patients when the O 2 saturation fell below 80% and was not corrected by a jaw thrust or stimulation [93]. Maharjan [94] suggest that ketamine anesthesia for cleft lip repair is practical and costeffective in remote areas in Nepal.…”

“…Anesthetics should be carefully titrated to effect during induction and maintenance of anesthesia because of variable effects of the anesthesia drugs at HA [62,83,89,90,[92][93][94]97]. Both narcotic analgesics and anesthetics blunt the hypoxic ventilatory drive and may therefore precipitate hypoxia during spontaneous ventilation [83,89].…”