Sk. Epstein et Rl. Ciubotaru, INFLUENCE OF GENDER AND ENDOTRACHEAL-TUBE SIZE ON PREEXTUBATION BREATHING PATTERN, American journal of respiratory and critical care medicine, 154(6), 1996, pp. 1647-1652
Citations number
27
Categorie Soggetti
Emergency Medicine & Critical Care","Respiratory System
An imbalance between work of breathing and respiratory muscle capacity
often results in rapid, shallow breathing (increased respiratory rate
/tidal volume [f/V-T]). Because this imbalance commonly causes unsucce
ssful weaning from mechanical ventilation, it is not surprising that a
n elevated f/VT accurately predicts weaning failure. However, while st
udying extubation outcome, we observed that women and patients with na
rrow endotracheal tubes are often successfully extubated with an eleva
ted f/VT. We studied 218 medical patients in the intensive care unit w
ho had a f/VT measured through an oral endotracheal tube (off of venti
latory support) during 1 min of spontaneous respiration at the onset o
f a weaning trial that culminated in extubation. Men and women were co
mparable at the onset of mechanical ventilation and weaning trials in
severity of illness, etiology of respiratory failure, ventilator setti
ngs, and gas exchange data. Women were found to have a higher f/VT (79
+/- 5 versus 56 +/- 3 breaths/L, p < 0.001), lower tidal volumes (381
+/- 14 versus 494 +/- 13 mi, p < 0.001), and higher respiratory rate
26 +/- 1 versus 24 +/- 1, p < 0.05). The differences persisted after c
ontrolling for extubation outcome. Smaller endotracheal tubes were ass
ociated with a higher f/VT, especially for women (less than or equal t
o 7 mm, 86 +/- 6 versus > 7 mm, 68 +/- 6, p < 0.05). Women were more l
ikely to have a f/VT greater than or equal to 100 (19/82 [women] versu
s 10/136 [men], p < 0.001). Although the overall incidence of extubati
on failure was similar (11/82 [women] versus 23/136 [men], p = NS), am
ong patients with f/VT >, 100, men were more likely to require reintub
ation (3/19 [women] versus 5/10 [men], p = 0.08). We conclude that wom
en, especially when breathing through small endotracheal tubes, have a
higher f/VT (including likelihood of f/VT greater than or equal to 10
0) than men, independent of extubation outcome. Consideration of facto
rs that elevate the f/VT, unrelated to physiologic work of breathing a
nd respiratory muscle capacity, should improve application of this ind
ex to extubation decision making.