Air sickness in flight: Frequency and factors☆

Many common beliefs based on anecdotal evidence are associated with the incidence of airsickness in patients cared for by helicopter air medical transport. Some of the most commonly held beliefs are that patients are more prone to nausea or vomiting in windy or rough flight conditions. Others believe that medical patients, especially cardiac patients, are more prone to this response regardless of flight conditions. However, a literature search revealed no formal information on this topic as it relates to patient care. Most research studied the effect of airsickness on pilots and medical crew and the relationship of diet and medications to its incidence.

Specific definitions of motion sickness and airsickness are necessary for this discussion. Stedman's Medical Dictionary defines motion sickness as the syndrome of pallor, nausea, weakness, and malaise that may progress to vomiting and incapacitation as a result of stimulation of the semiauricular canals. Airsickness is defined as motion sickness that occurs in an airplane or space flight as a result of erratic and continuous stimuli of the inner ear.

The purpose of this study was to evaluate all patients flown by a hospital-based, rotor-wing air medical service for the occurrence of airsickness. This service uses three aircraft: BK117B, BK117C, and Agusta 109 Power. Mission composition includes both interfacility and scene responses; data were collected for both. The average flight time from liftoff to landing at base was 1 hour and 47 minutes for interfacility transports and 1 hour and 8 minutes for scene responses.

This study was based on flight team observations. After a patient flight, 1of the team members completed a brief questionnaire, shown in Table 1, involving type of flight (trauma, cardiac, medical), weather conditions as perceived by the flight team (smooth, rough, windy), and patient complaint of nausea or vomiting. If nausea or vomiting was noted, an additional seven questions were asked, including previous history of motion sickness, complaint of nausea or vomiting before or during the flight, and any treatments rendered before or during the flight. Also, any adverse incidents, such as airway loss, arrythmia, or cardiac arrest, were noted.

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Fig.

Table Airsickness data collection sheet

Data were collected for 1 year: January 1, 2000, to December 31, 2000. A total of 745 questionnaires were completed (222 cardiac, 91 medical, 432 trauma). The total number of patients without complaint of nausea or vomiting was 690, or 93% of all patients flown (179 cardiac, 89 medical, 422 trauma). Of these patients, 488 were flown in weather conditions described as smooth; 202 were flown in conditions described as breezy, rough, or windy.

Twenty-one patients complained of nausea or vomiting before the flight but not during it (16 cardiac, 3 medical, 2 trauma). All the cardiac patients were treated with an antiemetic (11 Compazine, 2 Phenergan, 3 Dramamine) by either the referring staff or flight crew. No vomiting was noted in this group. Twenty-seven patients complained of nausea or vomiting in both the preflight and inflight environments (17 cardiac, 4 medical, 6 trauma). Of these patients, 14 received treatment from either the referring staff or flight crew with an antiemetic. Two cardiac patients who were not medicated with an antiemetic vomited (1 in flight on a smooth day, 1 at landing on a rough day).

Twenty-eight patients had no preflight complaint of nausea or vomiting but developed these symptoms in the flight environment (17 cardiac, 2 medical, 9 trauma). Six received treatment with an antiemetic, and 6 were noted to vomit (1 at landing and 5 in flight). Of these 6 patients who vomited, only 1 was cardiac (on a rough day), 4 were trauma (3 smooth and 1 rough), and 1 was a medical patient (on a smooth day).

A total of 55 patients (7%) complained of nausea or vomiting within the flight environment or immediately after flight (34 cardiac, 15 trauma, 6 medical). Of these patients, 8 (1% of all patients, 15% of those complaining of nausea) actually vomited. Six vomited within the flight environment and 2 immediately on landing (3 cardiac, 1 medical, 4 trauma). None of the patients who vomited were intubated, and no adverse patient occurrences were associated with vomiting.

This study appears to indicate that an overwhelming majority of patients (92%) flown by helicopter do not experience the symptoms of nausea or vomiting in flight regardless of weather conditions or type of patient. It also would appear that the administration of an antiemetic for a preflight complaint of nausea or vomiting is effective in preventing continued nausea or vomiting in flight, especially for cardiac patients. All 16 cardiac patients with a preflight complaint of nausea or vomiting who were so medicated did not vomit during the flight. Of the 223 total cardiac patients flown, 34 complained of nausea (15% of all cardiac patients), but only 3 (1%) actually vomited.

Also, 50% of the patients who actually vomited (n = 8) were trauma victims. While the association of head injury to vomiting was not specifically examined, it may be a contributing factor to nausea and vomiting within the flight environment. Overall patient outcomes do not appear compromised by the small number of patients actually vomiting because no adverse occurrences were associated with vomiting.

Some limitations of this study are the lack of sufficient data completion regarding patient history of motion sickness and more specific definition of actual weather conditions and time of day. Ambient and cabin temperature on hot days were frequently implicated as precursors to nausea and vomiting. Although temperature was a part of the data requested, it frequently was left blank on the collection tool. Finally, the timing of meals and the occurrence of nausea or vomiting was mentioned in the literature but not considered in this study.