Gun Öhqvist

Peritoneal Dialysis in Infants and Children After Open Heart Surgery

Over a period of 5 years, 1975-1979, 418 infants and children were operated on for congenital cardiac malformations using cardiopulmonary bypass. Fifteen patients (4 with transposition, 4 with Fallots tetralogy, 1 with pulmonary atresia and 6 with complex composite malformations) developed acute renal failure with anuria, which did not respond to volume load, afterload reduction, low dose dopamine, diuretics and controlled ventilation. Continuous peritoneal dialysis was started within a few hours of anuria. During dialysis the patients remained sedated, intubated and on controlled normocapnic ventilation. No complications occurred caused by the dialysis per se. Ten patients recovered and had normal serum creatinine when discharged from hospital (mean duration of dialysis: 6 days). Complex cardiac malformations were overrepresented in the 5 patients who died early in the postoperative period due to myocardial failure (mean duration of dialysis: 3 days).

Plasma Colloid Osmotic Pressure During Open-Heart Surgery Using Non-Colloid or Colloid Priming Solution in the Extracorporeal Circuit

Two different priming solutions for the heart-lung machine were compared in 14 patients during aortic valve replacement. Colloid osmotic pressure (COP), and albumin in plasma, blood erythrocyte volume fraction (B-EVF) and arterial oxygen tension (PaO2) (FIO2 = 1.0) were followed before, during and after perfusion. The two priming solutions were 2,000 ml Ringerdex (7 patients) or 1,800 ml Ringerdex + 200 ml 20% albumin (7 patients). COP and B-EVF were normal before bypass. After 10 min on bypass, when about 1,000 ml of crystalloid cardioplegic solution had been given, COP was reduced by about 50% and B-EVF fell to 23%, indicating a small loss of water from the circulation when compared with in vitro dilution curves. COP was slightly lower in the non-colloid group (p less than 0.02). Both COP and B-EVF remained unchanged during perfusion, despite transfusion from the heart-lung machine of a mixture of blood and crystalloid solution with a calculated very low COP (6 mmHg) and B-EVF (15%). After perfusion the restitution of COP and B-EVF was rapid and parallel. Both returned to normal levels after 2 hours. There was a good correlation between COP and albumin measured in the same plasma samples (r = 0.83, p less than 0.001). At one hour after bypass PaO2 (FIO2 = 1.0) tended to decrease in the non-colloid group, compared with preperfusion level. 40 g of albumin was a too small amount of colloid to diminish substantially the reduction of COP during perfusion. The unchanged levels of COP and B-EVF during perfusion, despite further dilution as well as the parallel normalization after perfusion, can only be explained by loss of water from the circulation.

Cerebral Blood Flow and Cerebral Metabolism in Children Following Cardiac Surgery with Deep Hypothermia and Circulatory Arrest. Clinical Course and Follow-Up of Psychomotor Development

Between November 1975 and June 1977, 49 children underwent repair of complicated cardiac defects with the aid of deep hypothermia. Circulatory arrest was used in 28 cases. Nine children died (18%) due to early postoperative heart failure. A decisive cause of death in terms of important cardiovascular defects, which were either unknown or not correctable at the time of repair, was found in 6 patients. Children with complicated forms of congenital heart disease requiring an extensive repair were overrepresented among those who died. Hence, there was an excess in the duration of bypass among nonsurvivors (p less than 0.01) whereas the patients age at operation, the use of circulatory arrest and the duration of aortic occlusion had no bearing on operative mortality. Cerebral blood flow (CBF) and cerebral metabolism were studied in 9 survivors. A negative correlation (r = -0.67) was found between the duration of circulatory arrest and CBF measured directly after surgery. CBF was reduced to values below 0.2 ml . g-1 . min-1 in 3 children with long periods of circulatory arrest. The cerebral uptake of oxygen and glucose was normal both before and after surgery. Two separate interviews with the parents were performed, the first one 3-22 months and the second one about 3 years after surgery. No serious neurological symptoms or psychomotor disturbances were reported. However, in 3 children operated with circulatory arrest, difficulties in performing more delicate motor activities were noted by the parents. The findings indicate that circulatory arrest should be used with caution and total arrest periods exceeding 60 min avoided.

Pulmonary oxygenation, central haemodynamics and glomerular filtration following cardiopulmonary bypass with colloid or non-colloid priming solution.

Plasma colloid osmotic pressure (COP), blood erythrocyte volume fraction (B-EVF), arterial oxygen tension at an inspired oxygen concentration of 30% (PaO2 (FIO2 0.3)), cardiac index, stroke volume, arterial mean pressure, left atrial mean pressure, pulmonary av-difference of oxygen (Ca-v O2) and creatinine clearance were studied in 16 patients during isolated aortic valve replacement. The patients were divided into two groups with different priming solutions in the oxygenator. In the non-colloid group 2,000 ml of Ringerdex was used, while the colloid group had 1,600 ml of Ringerdex and 400 ml of albumin 20% (80 g). COP differed significantly between the groups (p less than 0.01) during and for 1 hour after bypass. The greatest reductions were 56% and 30%, respectively. Haemodilution (los B-EVF) was of longer duration in the colloid group. No differences between the groups were found with respect to pulmonary oxygenation, myocardial behaviour or glomerular filtration rate. Cardiopulmonary bypass produced no changes in cardiac index, stroke volume, arterial mean pressure, left atrial mean pressure, Ca-v O2 or creatinine clearance in either of the groups. PaO2 (FIO2 0.3) remained unchanged in the non-colloid group and showed a small but significant reduction (p less than 0.01) in the colloid group. No positive effects of a colloid prime were demonstrated.

Effects of Intravenous Anesthesia on V̇A/V̇ DistributionA Study Performed during Ventilation with Air and with 50% Oxygen, Supine and in the Lateral Position

Distribution of ventilation and perfusion in relation to ventilation-perfusion ratio (&OV0312;A/&OV0312;) were studied in 14 patients, with a mean age of 59 yr, before elective lung surgery, in the supine position when awake, during intravenous anesthesia and mechanical ventilation with air, after increasing the fraction of inspired oxygen (FI02) to 0.5, and in the lateral position. Before anesthesia, small inert gas shunts and perfusion of low &OV0312;A/&OV0312; regions, indicating some degree of &OV0312;A/&OV0312; mismatch, were observed in several patients. After induction, FIo2 = 0.21, the major changes were a significant decrease in cardiac output and an increase in log SD for perfusion from 0.77 ± 0.45 (SD) to 1.13 ± 0.50 (SD), while the shunt remained low at 1% of cardiac output and arterial oxygen tension (PaO2) was unchanged. An increase to FIO2 = 0.5 induced only small changes with a shunt of 2.5% of cardiac output. In the lateral position, the shunt was 4.0% and increases in ventilation to high &OV0312;A/&OV0312; regions were observed. The lack of marked changes in the &OV0312;A/&OV0312; distribution after induction either could be a result of only minor alterations in the distribution of ventilation and perfusion or an effective vascular response to alveolar hypoxia (hypoxic pulmonary vasoconstriction, HPV).

Veno-venous extracorporeal membrane oxygenation with a heparin-coated system in adult respiratory distress syndrome

Three patients with adult respiratory distress syndrome were treated with veno-venous extracorporeal membrane oxygenation, ECMO, using a heparin-coated system for 8, 12 and 34 days, respectively. Despite extracorporeal blood flow of 4-5 l/min, the patients were ventilator-dependent in the initial period of ECMO. Two of the three patients showed bleeding diatheses despite only slightly elevated activated partial thromboplastin time (APTT). Blood platelet count followed a variable course and serum fibrinogen was normal. Acute pulmonary hypertensive crises, fatal systemic infection, recurrent pneumothorax and plasma leakage from the oxygenators were other main complications during ECMO. Two of the three patients survived, and follow-up showed that severely damaged lungs, if supported in the acute phase, can recover sufficiently to permit normal living.

Influence of glucose-insulin-potassium on left ventricular function during coronary artery bypass grafting.

To evaluate the hemodynamic effect of glucose-insulin-potassium administered during cardiopulmonary bypass grafting (CABG), i.v. infusion of glucose 0.5 g, insulin 1.35 IU and potassium 0.25 mmol/kg b.w/hour was begun after induction of anesthesia and continued until aortic cross-clamping in seven patients. Seven controls underwent CABG without such infusion. The left ventricular ejection fraction was measured after i.v. injection of Tc-99m-HSA before and at termination of cardiopulmonary bypass (CPB), in conjunction with invasive measurements to obtain left ventricular pressure-volume indices at end-systole and end-diastole. Three-step transfusion from the oxygenator was given before and after CPB in order to assess left ventricular contractility during volume-load, using the end-systolic pressure-volume index. Left ventricular contractility remained unchanged after CPB in the patients given glucose-insulin-potassium but decreased significantly in the controls. The left ventricular passive diastolic properties were unchanged after the ischemic period in both groups. The arterial glucose concentration rose markedly in the infused group (7.3-18.5 mmol/l) and moderately (6.4-8.2) in the controls. Glucose-insulin-potassium infusion thus favorably influenced left ventricular function during CABG by preventing decrease in contractility after CPB.

Changes in ejection fraction during induction of anesthesia with two different i.v. techniques

Two intravenous induction techniques were compared with respect to changes in ejection fraction (EF) and central hemodynamics in 30 patients scheduled for coronary artery surgery. Left ventricular EF was measured with a collimated single crystal probe linked to a microcomputer, after injection of 200 MBq Tc 99 m HSA. Stroke volume index (SI) determined by thermodilution and EF were used to calculate left ventricular volume in end‐systole and end‐diastole. In 20 patients (Group I), anesthesia was induced with diazepam (94 μg×kg‐1), thiopentone (3 mg·kg‐1) and fentanyl (3 μg×kg‐1). In 10 patients (Group II), fentanyl (30 μg×kg‐1) was used for induction. In Group I, EF decreased from 0.43 to 0.26 at intubation, while systemic vascular resistance index (SVRI) showed an increase. Left ventricular volume decreased during induction of anesthesia except during intubation. In Group II, EF and left ventricular volume remained unchanged during the study period. SVRI showed no increase at intubation. No change in contractility was indicated from the relation between the end‐systolic pressure and volume, in any of the groups.

The influence of isoflurane on blood flow in coronary bypass grafts.

The effects of isoflurane on graft blood flow, central hemodynamics and ECG were evaluated in 20 patients during coronary artery surgery in the period immediately after cardiopulmonary bypass (CPB). Intravenous anesthesia with thiopentone, diazepam, fentanyl (continuous infusion), droperidol and pancuronium supplemented with nitrous oxide was used before, and thiopentone and fentanyl were used during CPB. A first measurement of graft flow was performed during fentanyl infusion and the patients were randomly allocated to a control (n= 10) and a study (n= 10) group. In the study group isoflurane was administered in a dose that reduced systolic arterial blood pressure (SAP) to approximately 100 mmHg (13.3 kPa) (inspired concentration 0.5–1.5%) and a second measurement was performed after 30 min. In the control group the infusion of fentanyl was continued. Isoflurane reduced graft blood flow from 52 ± 5 (mean and s. e. mean) to 40 ± 5 ml × min‐1 (P<0.01) concomitant with reductions in SAP, cardiac index, stroke index, left ventricular stroke work index and power index, while these parameters as well as graft flow remained unchanged in the control group. Isoflurane did not produce any change in the degree of ischemia as judged from the ECG. A high blood flow in recently established coronary artery bypass grafts is essential for the prevention of early graft occlusion; therefore the graft‐flow‐reducing effect of isoflurane has to be taken into consideration when evaluating different anesthetic regimens in the period after CPB.

A comparative study of five different techniques to reduce left ventricular dysfunction during endotracheal intubation

Thirty‐five non‐selected, consenting patients were studied during induction of anesthesia before coronary artery bypass grafting. Anesthesia was induced with diazepam, thiopentone and fentanyl, followed by pancuronium. Before induction, 200 MBq Tc 99 m – HSA was given i.v. and ejection fraction (EF) of the left ventricle was measured with a collimated single‐crystal probe. The patients were allocated to five groups (seven patients in each) treated with: Group A: nitroglycerin i.v. bolus 4 μg x kg‐1 given 30–60 s before laryngoscopy; Group B: nitroglycerin i.v. in continuous infusion, 1 μg x kg‐1 x min‐1 started before induction; Group C: two‐stage topical anesthesia of the vallecula region and larynx with lidocain; Group D: a combination of nitroglycerin and topical anesthesia (as in Group B and C); and Group E: propranolol i.v. 0.01 mg x kg‐1 given 5 min before intubation. All groups reacted in the same way during induction of anesthesia up to the point of laryngoscopy. End‐diastolic volume and systemic arterial pressure decreased while cardiac index remained unchanged and EF increased. During laryngoscopy and intubation, however, differences between the groups were evident. Nitroglycerin i.v. as a bolus effectively prevented a reduction in EF and an increase in left ventricular volume. In addition to these beneficial hemodynamic effects, there was a moderate increase in heart rate and a reduction of stroke index. Continuous infusion of nitroglycerin and propranolol i.v. had no effect, since EF fell and left ventricular volume increased. Patients receiving topical anesthesia demonstrated a blunted response to endotracheal intubation with a moderate decrease in EF and an unchanged (Group C) or slightly increased (Group D) left ventricular volume.