Arnold Friedman

Isoflurane—A Powerful Coronary Vasodilator in Patients with Coronary Artery Disease

The coronary hemodynamic effects of 1% end-tidal isoflurane administered in oxygen-nitrogen by intermittent positive-pressure ventilation (IPPV) were investigated in 21 patients with stable coronary artery disease. Besides standard central hemodynamic measurements, coronary sinus blood flow was meas

Comparison of Hemodynamic, Electrocardiographic, Mechanical, and Metabolic Indicators of Intraoperative Myocardial Ischemia in Vascular Surgical Patients with Coronary Artery Disease

To compare mechanical, electrocardiographic, and metabolic indices of myocardial ischemia, the cardiokymogram (CKG), the V5 ECG, left anterior descending coronary artery territory lactate extraction, and pulmonary capillary wedge pressure (PCWP) were measured in 53 vascular surgical patients with coronary artery disease. Measurements were performed preoperatively and at four specific intraanesthetic intervals: after tracheal intubation, before surgery, and 10 and 30 min after incision. Measurements and sampling sequence took 5-7 min, and therapy for the probable cause of ischemia was instituted following completion of this sequence. Myocardial ischemia was defined as type II or III CKG, 0.1 mV or greater horizontal or downsloping depression of V5 ECG ST segment, 0.2 mV or greater elevation of V5 ECG ST segment, or myocardial lactate production. Thirty-nine patients (74%) had a total of 89 episodes of myocardial ischemia. Seventy-four episodes (83%) were detected by the CKG, 31 (44%) were evident on the ECG, and 13 (15%) by evidence of lactate production. The concordance among the indices of myocardial ischemia was poor. Patients with an abnormal preoperative ECG experienced a greater number of ischemic episodes (P less than 0.001). Elevation of PCWP or the presence of A-C or V-waves greater than 5 mmHg above the mean did not individually reflect ischemia reliably. Intraoperative myocardial ischemia is common in vascular surgical patients and is most sensitively detected by ventricular wall motion abnormality.

Effects of Thiopentone on Cardiac Performance, Coronary Hemodynamics and Myocardial Oxygen Consumption in Chronic Ischemic Heart Disease

Thiopentone was administered as induction agent for general anesthesia to eight patients with stable ischemic heart disease; 6 mg/kg of the drug induced decrease in arterial blood pressure (— 27%), systematic vascular resistance (— 20 %), stroke volume index (—14%), mean pulmonary arteriolar occlusion pressure (— 15%) and left ventricular stroke work index (— 38%), while heart rate increased by 10% and cardiac output remained unchanged. Total body oxygen consumption decreased by 30%. Myocardial oxygen consumption decreased by 39% with unchanged or decreased myocardial oxygen extraction and myocardial lactate uptake decreased by 40%. Arterial and coronary sinus hypoxanthine levels were unchanged and no ST‐T‐segment changes or dysrhythmias were recorded. In the present experimental setting, the results indicate that thiopentone substantially decreased myocardial oxygen requirements. In spite of the marked reduction in coronary perfusion, myocardial oxygen demand was matched by supply, myocardial dysoxia was not induced and cardiodepression was clinically negligible. Rate pressure product was a poor indicator of changes in myocardial oxygen consumption after thiopentone administration.

Anaesthesia for abdominal aortic surgery in patients with coronary artery disease, part II: effects of nitrous oxide on systemic and coronary haemodynamics, regional ventricular function and incidence of myocardial ischaemia

This study examines the effects of nitrous oxide on haemodynamics, anterior left ventricular (LV) function and incidence of myocardial ischaemia in abdominal vascular surgical patients with coronary artery disease. Forty–seven patients were randomly assigned to isoflurane–fentanyl anaesthesia with nitrous oxide–oxygen vs airoxygen (control). Systemic and coronary haemodynamics, 12–lead ECG, LV anterior wall modon by cardiokymography (CKG) and myocardial lactate balance were recorded at four intervals: before and during anaesthesia and 10 and 30 minutes into surgery. Systemic haemodynamics were controlled by anaesthetic dose, and, when insufficient, by iv nitroglycerine (NG) in case of LV failure (PCWP > 18 mmHg) and by phenylephrine during hypotension.

Hemodynamic and Cardiometabolic Effects of Prenalterol in Patients with Gram Negative Septic Shock

The hernodynamic eflects of prenalterol, a new inotropic agent, were investigated in 10 patients with gram negative septic shock. In four of the patients, coronary sinus blood flow (CSF) and myocardial oxygen and lactate extraction were also determined. After baseline hemodynamic measurements, prenalterol was infused intravenously over a 10‐min period to a total dose of 150 pg/kg. All patients responded within 15 min after completion of prenalterol infusion by increasing mean arterial pressure from 57±11 to 75 ± 20 mmHg (7.58f 1.46 to 9.97±2.66 kPa), (+32%), (P<0.01) and cardiac index from 2.65±0.40 to 3.80±0.47 l min‐l m‐2 (+44%) (P< 0.001). There was no change in heart rate or systemic vascular resistance, nor were any arrhythmias recorded. The urinary output increased significantly. After prenalterol, CSF increased from 185kl 4 to 246±14 ml.min‐1, (+33%), (P<0.001) and myocardial oxygen and lactate extraction rose from 19.8±2.1to26.6±2.1 ml O2.min‐1, (+ 34%) (P<0.00l) andfrom33.2±2.3 to44.7k2.1 μmol.min‐1, (+35%), (P<0.001), respectively. The total body oxygen consumption increased from 287f 13 to 348±23 ml O2.min‐1, (+21 %), (P<0.01) and the arterial lactate concentration decreased from 5.61±0.55 to 3.94±0. 16 mmol.l‐1, (‐ 30%), (P<0.01), suggesting improved tissue perfusion. The results demonstrate that prenalterol is a potent, highly selective inotropic agent inducing the same magnitude of increase in blood pressure and cardiac output as reported for dopamine in septic shock.

Anaesthesia for abdominal vascular surgery in patients with coronary artery disease (CAD), part I: isoflurane produces dose–dependent coronary vasodilation

The effects of anaesthesia for major abdominal vascular surgery on coronary flow regulation and mechanisms of myocardial ischaemia were studied in 56 patients with CAD, using a randomized, partly double–blinded protocol. After induction with fentanyl (3 μg–kg‐1) and thiopentone (2–4 mg kg‐1) and tracheal intubation, principal anaesthetics were nitrous oxide/oxygen (60/40) with isoflurane (n = 20), halothane (n = 19) or fentanyl (15–20 μg kg‐1) (n = 17). Conventional invasive techniques and coronary venous retrograde thermodilution were used to assess systemic and coronary haemodynamics. Coronary vascular resistance was estimated from myocardial oxygen extraction. Myocardial ischaemia was diagnosed by 12–lead ECG and/or anterior wall motion abnormalities by cardiokymography and/or myocardial lactate production. When adjustment of anaesthetic dose was insufficient for haemodynamic control, iv phenylephrine and nitroglycerine were adminstered to treat hypotension and hypertension or cardiac failure respectively. Measurements were performed at four specific intervals; awake, before surgery and 10 and 30 min after abdominal incision.

Hemodynamic and Cardiometabolic Effects of Prenalterol in Patients with Acute Myocardial Infarction and Shock

Five patients with acute myocardial infarction and shock were treated with a new, highly selective beta‐1‐adrenoreceptor agonist, prenalterol. After 1 and 2 mg of the drug, all patients had markedly increased blood pressure and cardiac output, but no changes in heart rate or systemic vascular resistance. Left‐ and right‐sided filling pressures decreased in three of the patients. In two of the patients, however, the increase in contractility and afterload was followed by a marked increase in left‐ and right‐sided filling pressures, and myocardial lactate uptake changed to lactate production. After addition of sodium nitroprusside, blood pressure and filling pressures returned towards normal, and myocardial lactate uptake was restored. As anticipated from the hemodynamic findings, myocardial oxygen consumption increased after prenalterol. It is suggested that the potent inotropic agent prenalterol may be used with great caution in cardiogenic shock.

Usefulness of transesophageal echocardiography for positioning the intraaortic balloon pump in the operating room

Abstract In conclusion, TEE is useful for precise positioning of the IABP catheter in the operating room without the use of x-ray fluoroscopy.