Hyperventilation following aero-medical rapid sequence intubation may be a deliberate response to hypoxemia.
BACKGROUND
Recent studies document a high incidence of hyperventilation by prehospital providers, with a potentially detrimental effect on outcome in traumatic brain injury (TBI).


OBJECTIVE
To document the incidence of hyperventilation by aero-medical providers and explore a possible relationship between hyperventilation episodes and desaturations or impending hypoxemia.


METHODS
This was a prospective, descriptive study using TBI patients undergoing prehospital RSI by aero-medical crews. Continuous data regarding end-tidal CO2 (EtCO2), ventilatory rate, and oxygen saturation (SpO2) were downloaded from hand-held oximeter-capnometer devices. Two investigators independently assessed oximetry/capnometry data to identify the following occurrences: desaturation during RSI (SpO2 < 90%), impending hypoxemia (SpO2 decrease by >or=3% to a value <95%) following intubation, loss of SpO2 signal, hyperventilation (EtCO2<30 mm Hg), and severe hyperventilation (EtCO2 < 25 mm Hg). Covariate analysis was used to explore the possible association between hyperventilation episodes and either desaturation, impending hypoxemia, or loss of SpO2 signal.


RESULTS
A total of 32 aero-medical patients were enrolled with a mean duration of ventilation monitoring of 14.8 min. The incidence of hyperventilation or severe hyperventilation was substantially lower than previously documented with ground paramedics. A total of 28 hyperventilation episodes were identified in 16 patients; 13 of these were associated with impending hypoxemia following intubation, five were associated with desaturation during RSI, and seven were associated with loss of SpO2 signal. The remaining three occurred immediately following intubation without desaturation during RSI. Desaturation was observed in 62% of patients; of note, desaturation was recorded on the quality improvement document in only 23% of these. Covariate analysis revealed an association between hyperventilation episodes and either desaturatios during RSI, impending hypoxemia following intubation, or loss of SpO2 signal.


CONCLUSIONS
The incidence of hyperventilation by aeromedical crews was lower than reported for ground paramedics and appears to occur in response to desaturation, impending hypoxemia, or loss of SpO2 signal.
Davis
Daniel P
DP
UCSD Medical Center, Department of Emergency Medicine, 200 West Arbor Drive, Malicode 8676, San Diego, CA 92103-8676, USA. davismd@cox.net
Douglas
Danielle J
DJ
Koenig
William
W
Carrison
Dale
D
Buono
Colleen
C
Dunford
James V
JV
D000328:Adult; D017732:Air Ambulances; D001930:Brain Injuries / Q000150:complications*; D004634:Emergency Medical Technicians; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000209:etiology*; D000860:Hypoxia / Q000150:complications*; D007442:Intubation, Intratracheal / Q000009:adverse effects* / Q000379:methods; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies
D010100:Oxygen