Phase-related changes in right ventricular cardiac output under volume-controlled mechanical ventilation with positive end-expiratory pressure.
OBJECTIVE
To examine determinants of right ventricular function throughout the ventilatory cycle under volume-controlled mechanical ventilation with various positive end-expiratory pressure (PEEP) stages.


METHODS
Prospective observational animal pilot study.


METHODS
Animal research laboratory at a university hospital.


METHODS
Eight healthy swine under volume- controlled mechanical ventilation.


METHODS
Flow probes were implanted in eight swine in order to continuously measure blood flow in the pulmonary artery and inferior vena cava. After a recovery phase of 14 days, the swine were subjected to various PEEP stages (0, 5, 10 cm H2O) during volume-controlled positive pressure ventilation.


RESULTS
Continuous flow measurement took place in the pulmonary artery and inferior vena cava. Data on standard hemodynamic parameters were additionally acquired. Respiration-phase-specific analysis of right ventricular cardiac output and of additional hemodynamic function parameters followed, after calculation of mean values throughout five respiration cycles. PEEP at 5 cm H2O led to significant decreases in inferior vena cava flow (4.1%), and in right ventricular cardiac output (5.2%); the respective decreases at PEEP 10 cm H2O were 13.9% and 18.3%. In the inspiration phase at PEEP 10 cm H2O, results revealed an overproportionally pronounced decrease in comparison with the expiration phase in inferior vena cava flow (-24.6% vs. -10%) and right ventricular cardiac output (-35% vs. -13.5%). This phenomenon is presumably caused by a PEEP-related increase in mean airway pressure by the amount of 10.7 cm H2O in inspiration.


CONCLUSIONS
Increases in PEEP during volume-controlled mechanical ventilation leads to respiration-phase-specific reduction of right ventricular cardiac output, with a significantly pronounced decrease during the inspiration phase. This decrease in cardiac output should be taken into particular consideration for patients with already critically reduced cardiac output.
Theres
H
H
Charité, Med. Klinik I, Berlin, Germany. Heinz.Therez@charite.de
Binkau
J
J
Laule
M
M
Heinze
R
R
Hundertmark
J
J
Blobner
M
M
Erhardt
W
W
Baumann
G
G
Stangl
K
K
D000403:Airway Resistance / Q000502:physiology; D000818:Animals; D002302:Cardiac Output / Q000502:physiology*; D002407:Catheterization, Swan-Ganz; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D010865:Pilot Projects; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology*; D013552:Swine; D013997:Time Factors; D014682:Vena Cava, Inferior / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology*