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Constant‐flow ventilation during experimental left ventricular failure
Author(s) -
Hachenberg T.,
Meyer J.,
SielenkÄmper A.,
Knichwitz G.,
Haberecht H.,
GÜlker H.,
Wendt M.
Publication year - 1990
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1990.tb03071.x
Subject(s) - medicine , preload , pulmonary wedge pressure , cardiology , cardiac output , oxygenation , ventilation (architecture) , anesthesia , hemodynamics , coronary perfusion pressure , resuscitation , cardiopulmonary resuscitation , mechanical engineering , engineering
The efficacy of constant‐flow ventilation (CFV) was investigated in dogs with normal heart function (control phase, n = 8) and after development of left ventricular failure (LVF phase, n = 8). Heated, humidified and oxygen‐enriched air (inspired oxygen fraction (Fio 2 )=0.4) was continuously delivered via two catheters positioned within each mainstem bronchus at two flow rates (1.2 and 1.6 1/kg/min). Conventional mechanical ventilation (CMV) with positive end‐expiratory pressure (PEEP) of 0.5 kPa was used as reference ventilation. During control, neither CMV with PEEP nor CFV revealed severe impairment of cardiopulmonary performance. Alveolo‐arterial Po 2 difference (P(A‐a)o 2 ) increased significantly during CFV 1.2 and CFV 1.6 , indicating a higher degree of ventilation‐perfusion (V A /Q) inhomogeneity. Acute left ventricular failure (LVF) was induced by proximal occlusion of the left anterior descending (LAD) coronary artery. Cardiac output (CO), maximum velocity of pressure development (dP/dt max and mixed venous Po 2 decreased (p0.05), whereas left ventricular end‐diastolic pressure (LVEDP) and pulmonary capillary wedge pressure (PCWP) increased (P0.05), Extravascular lung water (EVLW), as determined by thermal‐dye technique, increased from 10.1 ml/kg to 20.9 ml/kg (P0.01). Oxygenation, but not Co 2 elimination, deteriorated in the LVF phase. There were no haemodynamic differences between CMV with PEEP and CFV 1.2 , but cardiopulmonary performance deteriorated with CFV 1.6 . Gas exchange was significantly more impaired during CFV 1.2 and CFV 1.6 due to increased VA/Q mismatching. However, there were no significant differences for P (A‐a) o 2 values between CFV Contro , and CFV LVp This may be due to preferential ventilation of basal lung units with unchanged regional perfusion and redistribution of alveolar oedema towards non‐dependent parts of the lung. CFV maintains sufficient gas exchange in dogs with acute ischaemic cardiac failure. CMV with PEEP is more effective in achieving oxygenation and Co 2 elimination with fewer consequences for cardiopulmonary performance.