The effect of respiratory alkalosis on oxygen consumption in anesthetized patients.
OBJECTIVE
To investigate whether hyperventilation significantly altered oxygen consumption in anesthetized and paralyzed patients undergoing surgery.


METHODS
Open crossover trial with 1 hour of hyperventilation preceded and followed by 1 hour of normoventilation.


METHODS
University medical center.


METHODS
Eight patients (five men and three women) undergoing lengthy orthopedic surgery with general anesthesia and muscle paralysis.


METHODS
After baseline normoventilation for 1 hour (Period 1), the anesthetized patients were hyperventilated to an arterial carbon dioxide tension (PaCO2) of 20 to 25 mmHg for 1 hour (Period 2). Patients then experienced another hour of normoventilation (Period 3).


RESULTS
Hemodynamic variables, electrocardiography, temperature, end-tidal partial pressure of CO2 (PETCO2), oxygen consumption (VO2), carbon dioxide production, and minute ventilation were continuously followed throughout the study, and arterial blood gases were drawn at the beginning and end of each study period. During the period of hyperventilation, pH was significantly higher and P.ETCO2 and PaCO2 significantly lower compared with the periods of normoventilation. VO2 was significantly increased during hyperventilation compared with the periods of normoventilation. Hemodynamic variables and temperature were similar in the three study periods.


CONCLUSIONS
In anesthetized paralyzed patients, there is an increase in whole-body VO2 with hypocapnic alkalosis.
Slater
R M
RM
Department of Anesthesia, University of Iowa Hospitals and Clinics, Iowa City.
Symreng
T
T
Ping
S T
ST
Starr
J
J
Tatman
D
D
D000328:Adult; D000472:Alkalosis, Respiratory / Q000503:physiopathology*; D000771:Anesthesia, Intravenous; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology*; D008297:Male; D008723:Methohexital; D009985:Orthopedics; D010101:Oxygen Consumption / Q000502:physiology*; D017409:Sufentanil; D013997:Time Factors
D002245:Carbon Dioxide; D017409:Sufentanil; D008723:Methohexital