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Biomedical subjects

R A Bishop

Publications and source records attributed to R A Bishop.

17 recordsLinked to original sources
PubMed2001

Reascent following resolution of high altitude pulmonary edema (HAPE).

There is an absence of information in the literature regarding reascent to high altitude following resolution of HAPE (high altitude pulmonary edema). This report presents three cases of HAPE that are notable for later reascent to a high summit (up to 8,850 m) within the time course of each expedition. These cases illustrate that careful, gradual reascent following recovery and acclimatization after an episode of HAPE precipitated by rapid ascent may be considered. The pathophysiology of HAPE is reviewed with a focus on the evidence for rapid reversibility of pulmonary vascular injury. The evidence for protective pulmonary vascular remodeling is discussed to further support such a recommendation for cases of uncomplicated HAPE.

Acclimatization↗
PubMed2000

Ketamine anesthesia at high altitude.

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.

Acclimatization↗
PubMed2000

High-altitude global amnesia.

A variety of transient focal neurological signs presenting at high altitude have been described without associated acute mountain sickness or other concurrent illness. We report a case series of transient global amnesia at high altitude. The term high-altitude global amnesia (HAGA) is introduced to indicate this condition, and the pathophysiology is discussed. We hypothesize that because of the highly variable ventilatory response to hypoxia and to individual cerebral vasomotor reactivity, individuals with a marked hyperventilatory response could experience significant hypocapnic cerebral vasoconstriction that in turn could cause local hypoxia or ischemia to particular regions of the brain and resulting transient focal neurological impairment.

Adult↗
PubMed2000

Oxygen concentrators for the delivery of supplemental oxygen in remote high-altitude areas.

Oxygen concentrators are a relatively new technology for the delivery of supplemental oxygen. Readily available for domicile use in modern countries, these machines have proved reliable. The application of oxygen concentrators for the supply of medical oxygen in remote high-altitude settings has important cost-saving and supply implications. In our experience at a remote hospital at 3,900 m in the Nepal Himalayas, oxygen concentrators constitute an effective and affordable means to supply medical oxygen. Using an air compressor and 2 zeolite chambers, the machine traps nitrogen from room air compressed to 4 atm, thus concentrating oxygen in the expressed gas. At delivery flow rates of 2 to 5 liters per minute, oxygen concentrations greater than 80% can be maintained. An electric power requirement of less than 400 W can be provided from a variety of sources, including a small gasoline generator, a solar or wind power system with battery store, or a domestic or commercial power source. At our facility, a cost savings of 75% for supplemental oxygen was found in favor of the oxygen concentrator over cylinders (0.17 US cents per liter vs 0.79 US cents per liter).

Altitude Sickness↗
PubMedDate not supplied

Polyneuropathy.

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Humans↗