Oxygenation equilibration time after alteration of inspired oxygen in critically ill patients.
To determine the time required for arterial oxygen partial pressure (Pao(2)) equilibration after a change in fractional inspired oxygen (Fio(2)) in intensive care unit (ICU) patients, a prospective study in a 7-bed university ICU was performed. Forty adult patients were examined using sequential arterial blood gas measurements after a .3 alteration in Fio(2). The Pao(2) value measured at 30 minutes after a step change in Fio(2) in both periods was accepted as representative of the equilibrium value for Pao(2). The mean equilibration time was 8.26+/-5.6 minutes and 4.5+/-2.65 minutes for increases and decreases in Pao(2), respectively (P=.003). The constant k values were .44 +/- .31 minutes and .72 +/- .7 minutes for increases and decreases in Pao(2), respectively. There was no significant difference between the increase and the decrease of 90% oxygenation times in the 2 groups (P=.150 and P=.446, respectively). The study confirms that a period of less than 10 minutes is adequate for 90% of the equilibration of Pao(2) to occur after an Fio(2) change in ICU patients.
Fildissis
George
G
National and Kapodistrian University of Athens, ICU, KAT General Hospital, Nikis 2, 14561, Kifissia, Athens, Greece. fildiss@nurs.uoa.gr
Katostaras
Theofanis
T
Moles
Athanassios
A
Katsaros
Andreas
A
Myrianthefs
Paylos
P
Brokalaki
Hero
H
Tsoumakas
K
K
Baltopoulos
George
G
D018806:APACHE; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis; D016638:Critical Illness; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D016018:Least-Squares Analysis; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage / Q000097:blood*; D010102:Oxygen Inhalation Therapy; D011446:Prospective Studies; D013997:Time Factors
D010100:Oxygen