The Effects of Sevoflurane, Isoflurane and Propofol During Cardiac Surgery

All patients were divided into 2 groups according to the type of disease: the first (1) group with coronary heart disease. The second (2) group with valvular heart disease. There were 65 patients in the first group and 22 in the second. Both groups were divided into 3 subgroups according to the type of anaesthesia: patients anaesthetised with propofol, with sevoflurane, with isoflurane.

The study was conducted in 5 stages:

1. Initial haemodynamic parameters and oxygen transport function of the patient's blood before anaesthesia were determined;
2. after tracheal intubation;
3. Before the CPB;
4. after the CPB;
5. The post-operative period until the patient is extubated. Before induction into anaesthesia, haemodynamic monitoring was started on admission to the operating theatre using a Nihon Kohden monitor (Japan). The right radial artery was catheterised for invasive monitoring of systemic arterial pressure and arterial blood sampling, and a catheter was then inserted into the central jugular vein (under ultrasound machine control) and guided into the right atrium for mixed venous blood sampling.

Cardiac stroke volume was determined by transthoracic echocardiography (CS=end diastolic volume - end systolic volume). Cardiac output (CO=CS x heart rate), cardiac index (CI=CO/body surface area) were determined. We determined blood oxygen content using the formula CaO2 (arterial ABB) and CvO2 (central mixed venous ABB) = [(1.34 × Hb × SO2) + (PO2 × 0.031)] / 100. Arteriovenous difference = CaO2-CvO2. Oxygen delivery was determined using the formula (DO2 = CI* CaO2). Oxygen consumption (VO2 = Cardiac index (CI)*AVD or VO2 = CO × (CaO2 - CvO2) ~ CO × Hb × 1.34 × (SaO2 - SvO2) / 100).

In the second stage, after tracheal intubation, indirect calorimetry was used to determine VO2, energy expenditure during anaesthesia using a Spirometry device (Oxford, UK), which was connected to an endotracheal tube and continuously showed oxygen demand and energy expenditure. A transesophageal echocardiography sensor was used to determine cardiac output. Additionally, the cardiac output was determined by Fick's formula in patients with CHD. The same tests (cardiac output, cardiac index, consumption, oxygen delivery, energy expenditure) were performed in the third and fourth stages of anaesthesia. In the last stage, the consumption of muscle relaxants and opioid analgesics was calculated to assess the pharmaco-efficiency of anaesthetics. The time of extubation and the time of transfer of the patient to the specialist department were determined.

All patients continued antihypertensive medication both before and on the day of surgery to prevent the development of withdrawal syndrome and to reduce the risk of perioperative myocardial ischaemia.

All patients in both groups were anesthetized with fentanyl at a dose of 5-7 µg/kg, ketamine 1.5-2 mg/kg, and propofol 1-1.5 mg/kg intravenously fractionally. Pipecuronium bromide 0.04-0.07 mg/kg was used as muscle relaxant in all patients. To maintain anaesthesia in Group 1 P, propofol was used as an anaesthetic in a dose of 4-6 mg/kg/h intravenously on a perfusor (BBRAUN). In Group 2, sevoflurane was used as an anaesthetic in a dose of - 1.7-1.9 MAC. In Group 3 isoflurane was used as the anesthetic in the dose of 1.1-1.2 MAC. Fentanyl 100 µg intravenously was administered fractionally in all groups to increase heart rate and blood pressure, and pipecuronium bromide 2 mg intravenously for myorelaxation. During CPB, propofol at a dose of 6 mg/kg/h intravenously via perfusion was used in all patients in all groups. Anaesthesia regimen: fentanyl 100 µg IV every 30 min; myorelaxant pipecuronium bromide 2 mg every 40-60 min. Norepinephrine solution was administered at a dose of 0.07 µg/kg/min intravenously on perfusion and dobutamine 5 µg/kg/min after CPB in all patients at the same dosages in all groups.