Effects of positive end-expiratory pressure on right ventricular function in COPD patients during acute ventilatory failure.
OBJECTIVE
To examine the effects of external positive end-expiratory pressure (PEEP) on right ventricular function in chronic obstructive pulmonary disease (COPD) patients with intrinsic PEEP (PEEPi).


METHODS
Prospective study.


METHODS
General intensive care unit in a university teaching hospital.


METHODS
Seven mechanically ventilated flow-limited COPD patients (PEEPi = 9.7 +/- 1.3 cmH2O, mean +/- SD) with acute respiratory failure.


METHODS
Hemodynamic and respiratory mechanic data were collected at four different levels of PEEP (0-5-10-15 cmH2O).


RESULTS
Hemodynamic parameters were obtained by a Swan-Ganz catheter with a fast response thermistor. Cardiac index (CI) and end-expiratory lung volume (EELV) reductions started simultaneously when the applied PEEP was approximately 90% of PEEPi measured on 0 cmH2O (ZEEP). Changes in transmural intrathoracic pressure (PEEPi,cw) started only at a PEEP value much higher (120%) than PEEPi. The reduction in CI was related to a decrease in the right end-diastolic ventricular volume index (RVEDVI) (r = 0.61; p < 0.001). No correlation between CI and transmural right atrial pressure was observed. The RVEDVI was inversely correlated with PEEP-induced changes in EELV (r = -55; p < 0.001), but no with PEEPi,cw (r = -0.08; NS). The relationship between RVEDVI and right ventricular stroke work index, considered an index of contractility, was significant in three patients, i.e., PEEP did not change contractility. In the other patients, an increase in contractility seemed to occur.


CONCLUSIONS
In COPD patients an external PEEP exceeding 90% of PEEPi causes lung hyperinflation and reduces the CI due to a preload effect. The reduction in RVEDVI seems related to changes in EELV, rather than to changes in transmural pressures, suggesting a lung/heart volume interaction in the cardiac fossa. Thus, in COPD patients, application of an external PEEP level lower than PEEPi may affect right ventricular function.
Dambrosio
M
M
Istituto di Anestesiologia e Rianimazione, Università degli Studi di Bari, Italy.
Cinnella
G
G
Brienza
N
N
Ranieri
V M
VM
Giuliani
R
R
Bruno
F
F
Fiore
T
T
Brienza
A
A
D000208:Acute Disease; D000368:Aged; D002302:Cardiac Output; D005260:Female; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D011175:Positive-Pressure Respiration / Q000379:methods*; D018467:Positive-Pressure Respiration, Intrinsic / Q000150:complications*; D011446:Prospective Studies; D013318:Stroke Volume; D016278:Ventricular Function, Right