Variable ventilation improves perioperative lung function in patients undergoing abdominal aortic aneurysmectomy.
BACKGROUND
Optimizing perioperative mechanical ventilation remains a significant clinical challenge. Experimental models indicate that "noisy" or variable ventilation (VV)--return of physiologic variability to respiratory rate and tidal volume--improves lung function compared with monotonous control mode ventilation (CV). VV was compared with CV in patients undergoing abdominal aortic aneurysmectomy, a patient group known to be at risk of deteriorating lung function perioperatively.


METHODS
After baseline measurements under general anesthesia (CV with a tidal volume of 10 ml/kg and a respiratory rate of 10 breaths/min), patients were randomized to continue CV or switch to VV (computer control of the ventilator at the same minute ventilation but with 376 combinations of respiratory rate and tidal volume). Lung function was measured hourly for the next 6 h during surgery and recovery.


RESULTS
Forty-one patients for aneurysmectomy were studied. The characteristics of the patients in the two groups were similar. Repeated-measures analysis of variance (group x time interaction) revealed greater arterial oxygen partial pressure (P = 0.011), lower arterial carbon dioxide partial pressure (P = 0.012), lower dead space ventilation (P = 0.011), increased compliance (P = 0.049), and lower mean peak inspiratory pressure (P = 0.013) with VV.


CONCLUSIONS
The VV mode of ventilation significantly improved lung function over CV in patients undergoing abdominal aortic aneurysmectomy.
Boker
Abdulaziz
A
Department of Anesthesia and Critical Care, Abdulaziz University, Jeddah, Saudi Arabia.
Haberman
Craig J
CJ
Girling
Linda
L
Guzman
Randy P
RP
Louridas
George
G
Tanner
John R
JR
Cheang
Mary
M
Maycher
Bruce W
BW
Bell
Dean D
DD
Doak
Greg J
GJ
D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery*; D001831:Body Temperature / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D001261:Pulmonary Atelectasis / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics; D012727:Sex Characteristics; D012907:Smoking / Q000503:physiopathology; D013990:Tidal Volume / Q000502:physiology