RELATION BETWEEN DICROTIC NOTCH AND MEAN PULMONARY-ARTERY PRESSURE STUDIED BY USING A SWAN-GANZ CATHETER IN CRITICALLY ILL PATIENTS

Objective: It has been recently shown that there is a match between di crotic notch and mean pulmonary artery (PA) pressures in spontaneously breathing patients studied by means of high-fidelity pressure cathete rs. The aim of the study was to analyze the relation between mean PA p ressure and PA pressure at the incisura by using a Swan-G ant catheter in critically ill, mechanically ventilated patients. Measurements and results: Fluid-filled PA pressures were obtained over four ventilator y cycles in 32 consecutive, mechanically ventilated patients in the in tensive care unit. We measured mean PA pressure and dicrotic notch pre ssure. We also calculated the widely used approximation of mean PA pre ssure (mean PAP(approx) = diastolic + 1/3 pulse pressure). Cardiac out put was measured in triplicate by using the thermodilution technique. Dicrotic notch was clearly identified in 30 of 32 patients. Mean PA pr essure (32.1 +/- 10.2 mm Hg) and PA dicrotic notch pressure (31.8 +/- 10.4 mm Hg) were linearly related (r = 0.989, p < 0.001). Agreement be tween dicrotic notch and mean PA pressures was suggested (mean differe nce +/- SD = -0.3 +/- 1.5 mm Hg). Similar agreement was found between mean PAP(approx) and mean PA pressure (mean difference +/- SD = -0.7 /- 0.8 mm Hg; p = 0.20). Conclusion: By using a Swan-Ganz catheter we found that dicrotic notch pressure equalled mean PA pressure in the cr itically ill, mechanically ventilated patients studied. This indicated that right-sided ejection was com pleted at a PA pressure equal to me an PA pressure in these patients.