Lung overinflation without positive end-expiratory pressure promotes bacteremia after experimental Klebsiella pneumoniae inoculation.
OBJECTIVE
To determine the effect of peak inspiratory pressure (PIP) and positive end-expiratory pressure (PEEP) on the development of bacteremia with Klebsiella pneumoniae after mechanical ventilation of intratracheally inoculated rats.


METHODS
Prospective, randomized, animal study.


METHODS
Experimental intensive care unit of a University.


METHODS
Eighty male Sprague Dawley rats.


METHODS
Intratracheal inoculation with 100 microliters of saline containing 3.5-5.0 x 10(5) colony forming units (CFUs) K. pneumoniae/ml. Pressure-controlled ventilation (frequency 30 bpm; I/E ratio = 1:2; FIO2 = 1.0) for 180 min at the following settings (PIP/PEEP in cmH2O): 13/3 (n = 16); 13/0 (n = 16); 30/10 (n = 16) and 30/0 (n = 16), starting 22 h after inoculation. Arterial blood samples were obtained and cultured before and 180 min after mechanical ventilation and immediately before sacrifice in two groups of non-ventilated control animals (n = 8 per group). After sacrifice, the lungs were homogenized to determine the number of CFUs K. pneumoniae.


RESULTS
The number of CFUs recovered from the lungs was comparable in all experimental groups. After 180 min, 11 animals had positive blood cultures for K. pneumoniae in group 30/0, whereas only 2, 0 and 2 animals were positive in 13/3, 13/0 and 30/10, respectively (p < 0.05 group 30/0 versus all other groups).


CONCLUSIONS
These data show that 3 h of mechanical ventilation with a PIP of 30 cmH2O without PEEP in rats promotes bacteremia with K. pneumoniae. The use of 10 cmH2O PEEP at such PIP reduces ventilation-induced K. pneumoniae bacteremia.
Verbrugge
S J
SJ
Department of Anesthesiology, Erasmus University Rotterdam, The Netherlands.
Sorm
V
V
van 't Veen
A
A
Mouton
J W
JW
Gommers
D
D
Lachmann
B
B
D000818:Animals; D016470:Bacteremia / Q000209:etiology* / Q000382:microbiology; D007362:Intensive Care Units; D007710:Klebsiella Infections / Q000209:etiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae; D008297:Male; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods*