H Haberecht | PubMed Health

PubMed1991

Cardiopulmonary effects of internal cardioverter/defibrillator implantation.

Cardiopulmonary effects of electrophysiological testing of internal cardioverter/defibrillator (ICD) devices were studied in ten patients undergoing general anaesthesia. In the control-phase, haemodynamic performance and oxygenation were slightly impaired. After completion of the electrophysiological procedures (ICD-phase), cardiopulmonary function had deteriorated significantly. Cardiac index declined by 16%, whereas left ventricular filling pressure and pulmonary vascular resistance increased (P less than or equal to 0.01). Oxygenation, but not CO2-elimination deteriorated (P less than or equal to 0.01) and venous admixture increased by 72% (P less than or equal to 0.01). Alveolo-arterial PO2-difference (PA-aO2) increased by 43% (P less than or equal to 0.01), indicating ventilation-perfusion (VA/Q) mismatching. Repeated inductions of ventricular tachycardia and/or fibrillation subject the myocardium to transient global ischaemia, leading to acute congestive heart failure, and positive inotropic intervention was necessary in 40% of the patients. Partial pulmonary insufficiency resulted possibly from interstitial oedema and VA/Q-inhomogeneities. ICD implantation has detrimental effects on haemodynamics and gas exchange in patients with impaired left ventricular function.

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PubMed1990

Constant-flow ventilation during experimental left ventricular failure.

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 (Fio2) = 0.4) was continuously delivered via two catheters positioned within each mainstem bronchus at two flow rates (1.2 and 1.6 l/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 PO2 difference (P(A-a)O2) increased significantly during CFV1.2 and CFV1.6, indicating a higher degree of ventilation-perfusion (VA/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/dtmax) and mixed venous PO2 decreased (P less than or equal to 0.05), whereas left ventricular end-diastolic pressure (LVEDP) and pulmonary capillary wedge pressure (PCWP) increased (P less than or equal to 0.05). Extravascular lung water (EVLW), as determined by thermal-dye technique, increased from 10.1 ml/kg to 20.9 ml/kg (P less than or equal to 0.01). Oxygenation, but not CO2 elimination, deteriorated in the LVF phase. There were no haemodynamic differences between CMV with PEEP and CFV1.2, but cardiopulmonary performance deteriorated with CFV1.6. Gas exchange was significantly more impaired during CFV1.2 and CFV1.6 due to increased VA/Q mismatching. However, there were no significant differences for P(A-a)O2 values between CFVControl and CFVLVF.(ABSTRACT TRUNCATED AT 250 WORDS)

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