Right atrial pressure predicts hemodynamic response to apneic positive airway pressure.
OBJECTIVE
To evaluate if the preexistant filling state, assessed by right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), and right ventricular end-diastolic volume index (EDVI), would define the subsequent hemodynamic effects of increases in airway pressure (Paw).


METHODS
Prospective open clinical study.


METHODS
Postoperative intensive care unit, university hospital.


METHODS
Twenty-two consecutive ventilator-dependent patients with mild to severe acute lung injury with Murray scores (scoring infiltrates on chest radiograph, oxygenation index, lung compliance, and the level of positive end-expiratory pressure) ranging from 0.5 to 3.0 without history of preexisting cardiopulmonary disease.


METHODS
Paw varied during apnea from 0 to 10, 20, and 30 cm H2O using inspiratory hold maneuvers of 15 secs.


RESULTS
Cardiac index and right ventricular ejection fraction were measured by the thermodilution technique. We made measurements in triplicate using manual injection of iced saline. Right ventricular volumes were calculated. Increasing Paw induced variable changes in cardiac index among subjects (+6% to -43% change from baseline 0 cm H2O Paw values), which correlated with percentage changes in both stroke index (r2 = .89) and right ventricular EDVI (r2 = .75), whereas heart rate and right ventricular ejection fraction did not change. The change in cardiac index from 0 to 30 cm H2O Paw correlated with baseline values for RAP, PAOP, and right ventricular EDVI (r2 = .68, .43, and .34, respectively, p < 0.01). Increases in RAP correlated with lung compliance if baseline RAP was >10 mm Hg but did not if it was < or =10 mm Hg. Similarly, patients with baseline RAP < or =10 mm Hg had a greater decrease in cardiac index than patients with a RAP >10 mm Hg (for 30 cm H2O Paw: -30% +/- 9% vs. -8% +/- 7%, p < .01).


CONCLUSIONS
Apneic positive Paw decreased cardiac output mainly by reducing venous return. From the investigated filling variables, RAP was most sensitive in predicting the hemodynamic response, followed by PAOP and right ventricular EDVI. Patients with RAP < or =10 mm Hg, if subjected to aggressive positive pressure ventilation, are at risk of hemodynamic deterioration and organ hypoperfusion.
Jellinek
H
H
Department of Anaesthesia and General Intensive Care, Community Hospital Lainz, Vienna, Austria.
Krafft
P
P
Fitzgerald
R D
RD
Schwarz
S
S
Pinsky
M R
MR
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016280:Atrial Function, Right; D002303:Cardiac Output, Low / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006334:Heart Function Tests; D006439:Hemodynamics; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000009:adverse effects*; D011669:Pulmonary Wedge Pressure; D012128:Respiratory Distress Syndrome / Q000628:therapy*; D012680:Sensitivity and Specificity; D016278:Ventricular Function, Right