Tb. Gilbert et al., IMPACT OF PLEUROTOMY, CONTINUOUS POSITIVE AIRWAY PRESSURE, AND FLUID BALANCE DURING CARDIOPULMONARY BYPASS ON LUNG-MECHANICS AND OXYGENATION, Journal of cardiothoracic and vascular anesthesia, 10(7), 1996, pp. 844-849
Citations number
26
Categorie Soggetti
Anesthesiology,"Peripheal Vascular Diseas","Cardiac & Cardiovascular System
Objective: To determine effects of surgical pleurotomy, continuous pos
itive airway pressure, and fluid balance during cardiopulmonary bypass
(CPB) on lung mechanical properties and indices of oxygenation. Desig
n: Prospective, descriptive. and interventional study. Setting: Cardio
thoracic service at a major university referral center. Participants:
Eighteen anesthetized-paralyzed patients undergoing elective coronary
artery bypass grafting requiring CPB. Interventions: During CPB, conti
nuous positive airway pressure (CPAP) was applied to nine patients; in
nine others, no CPAP was applied. Measurements and Main Results: From
measurements of airway and esophageal pressures and flow, lung resist
ance and elastance were determined before sternotomy and after sternal
reapproximation. Measurements were made during forced ventilation ove
r a physiologic range of tidal volumes and frequencies, and frequency
and volume dependences of lung resistance and elastance were additiona
lly identified. in all patients. lung resistance and elastance increas
ed after CPB, consistent with models of pulmonary edema. Multiple regr
ession analysis showed that these increases were relatively less in pa
tients with intact pleurae (p < 0.05) or net negative fluid balance (p
< 0.05); however, no difference in these increases was noted between
patients receiving CPAP and those receiving no CPAP. Increases in lung
resistance were positively correlated to net fluid balance, and negat
ively correlated to frequency and tidal volume (p < 0.05). Increases i
n lung elastance were positively correlated to body mass index and fre
quency, and negatively correlated to tidal volume (p < 0.05). Absolute
change in alveolar-arterial oxygen gradient was negatively correlated
with net fluid balance, whereas percentage change was positively corr
elated to changes in lung elastance (p < 0.05). Conclusions: These fin
dings suggest that pleurotomy before CPB and positive fluid balance du
ring CPB enhance postbypass pulmonary edema and/or atelectasis. as dem
onstrated by acute changes in respiratory mechanics and indices of oxy
genation. Low levels of CPAP applied during CPB did not significantly
change either mechanical properties or oxygenation. Copyright (C) 1996
by W.B. Saunders Company