This paper discusses our technique of carrying out cervical and ocular vestibular-evoked myogenic potential testing in a single position. The described technique allows for a symmetrical, natural flexion of the neck muscles, which is helpful as many of our patients have suffered traumatic deceleration injures.

Patients with suspected vestibular pathology referred by specialists were sequentially assessed in a tertiary referral neuro-otology unit within a teaching hospital using our technique and our previously established normative database. All patients underwent standardised vestibular assessment in addition to cervical and ocular vestibular-evoked myogenic potential assessment. Our normative data are in keeping with that reported by other centres.

Many of the patients had abnormal vestibular-evoked myogenic potentials, which is in line with a history suggesting otolithic disease.

Both cervical and ocular vestibular-evoked myogenic potentials offer several parameters for detecting abnormalities. The technique reported enables us to assess patients in an accurate fashion whether or not they have suffered traumatic neck injuries.

Otolithic function is poorly understood, but vestibular-evoked myogenic potential testing has allowed the documentation of pathology in patients who complain of imbalance.

Seventy-four patients with traumatic and non-traumatic vestibular disease were sequentially assessed at a tertiary referral neuro-otology unit in a teaching hospital. A detailed history of all patients was taken and standard vestibular assessment was conducted using the technique described in the companion paper. The results of both groups of patients were analysed and the rate of abnormalities was assessed.

There was a high rate of abnormalities, including bilateral pathology, in a significant number of patients. Many patients in both groups inexplicably failed to recover.

Vestibular-evoked myogenic potentials are helpful in documenting pathology, including bilateral pathology, which is outlined in the literature as being exceedingly difficult to compensate for.

Devices used for support of patients requiring air rescue or conveyance are subjected to severe environments that may affect their ability to function when needed or may affect other systems within the transporting vehicle.

The ability of four portable ventilators, a suction device, and plastic and rubber tracheal tubes to withstand changes in temperature, vibration, sudden deceleration, and electromagnetic fields was studied in the laboratory setting. In addition, the effects of the operation of these devices on the flight instrumentation was investigated.

All of the ventilators tested delivered stable minute volumes at temperatures above zero, but in sub-zero temperatures problems were encountered with the driving gas. Vibrations produced alterations in the performance of two of the ventilators, and resonant frequencies were detected that are identical to those produced by the rotors of the helicopter used.

Suctioning became difficult at temperatures below −5° C as the mucus froze in the collecting tubing. The motor produced electromagnetic fields that interfered with the aircraft instrumentation, and resonant frequencies had a deleterious effect on the circuit boards. Plastic tubes were adversely affected by cold, and these chilled tubes were excessively sensitive to vibration and shocks.

The devices used in various aircraft influence certain vital maneuver systems of the craft. Studies on portable ventilators, a suction device, and tracheal tubes showed that, under specific conditions, the equipment was safe to patients and was not hazardous to the aviation safety. However, under certain conditions commonly encountered during air rescue operations, the equipment became dys-functional or presented safety hazards to the aircraft, and, hence, the crew. The Swedish Air Force has adopted three different criteria constellations: 1) operative; 2) storing; and 3) transport environment.