Anders Öwall

Effects on the bispectral index during medium‐high dose fentanyl induction with or without propofol supplement

Background: The search for a drug‐independent monitor to determine depth of anaesthesia and hypnosis continues. The bispectral analysis (BIS) of the EEG correlates well with the clinical dose–response of hypnotic drugs during induction, but the effect on BIS of an opiate induction, as for coronary bypass surgery, is not known.

Patient-controlled versus nurse-controlled pain treatment after coronary artery bypass surgery.

Background: Pain after coronary artery bypass surgery persists for several days. A continuous intravenous infusion of an opioid adequately accomplishes good pain control in the intensive care unit, but it is often not suitable on the ordinary ward. Patient‐controlled analgesia (PCA) with intermittent injections delivered by one of the new devices now available could be an alternative to conventional nurse‐controlled analgesia (NCA) based on intermittent injections. The aim was to compare these two techniques with respect to efficacy and the amount of opioid used.

Cardiac outcome after sevoflurane versus propofol sedation following coronary bypass surgery: a pilot study.

Background: Studies of volatile anesthetic administration during coronary artery bypass grafting (CABG) report reduced serum levels of post‐operative cardiac troponin‐T (cTnT). Our primary objective was to evaluate whether short‐term sedation with sevoflurane in the intensive care unit (ICU) – after CABG – could affect the release of cTnT, compared with propofol sedation.

Evaluation of a continuous blood glucose monitoring system using a central venous catheter with an integrated microdialysis function.

INTRODUCTION Glycemic control in critically ill patients has been the topic of an interesting debate during the last decade. An accurate continuous glucose monitoring system is essential to better understand this field. This prospective study thus evaluates the accuracy and technical feasibility of a continuous glucose monitoring system using intravascular microdialysis. PATIENTS AND METHODS Thirty patients undergoing cardiac surgery were monitored using a triple-lumen central venous catheter (Eirus TLC; Eirus Medical AB, Solna, Sweden) with an integrated microdialysis function. The catheter functions as a central venous catheter, enabling blood sampling and administration of infusions and medication while simultaneously providing continuous glucose monitoring. The patients were monitored for up to 48 h postoperatively. As reference, arterial blood gas samples were taken every hour and analyzed in a blood gas analyzer. RESULTS Six hundred seven paired samples were obtained for analysis. Using Clarke Error Grid analysis, 100% of the paired samples were in Zones A+B, and 97% were in Zone A. Mean difference (bias) was -0.12 mmol/L, and mean absolute relative difference was 5.6%. Of the paired samples, 97.5% were correct according to International Organization for Standardization criteria. Bland-Altman analysis showed bias ± limits of agreement were -0.12 ± 0.7 mmol/L. No hypoglycemic episodes were observed. CONCLUSIONS Central venous microdialysis is an accurate and reliable method for continuous blood glucose monitoring up to 48 h in patients undergoing cardiac surgery. With the microdialysis function integrated in a central venous catheter, no extra device for the continuous glucose monitoring is required. The system may be useful in critically ill patients.

Effects of Adenosine-induced Hypotension on Myocardial Hemodynamics and Metabolism in Fentanyl Anesthetized Patients with Peripheral Vascular Disease

The effects of adenosine on central and myocardial hemodynamics and metabolism were evaluated during fentanyl anesthesia (100 μg·kg−1) in six patients with peripheral vascular disease. Adenosine was intravenously infused, at a rate of 90 ± 20 (SEM) μkg−1·min−1, to reduce mean arterial blood pressure by approximately 20% (23 ± 2% SEM, from 82 ± 3 to 63 ± 3 SEM mmHg) during a 20-min period. Systemic and pulmonary vascular resistance indices decreased by 36 ± 3 and 32 ± 6% (SEM), and cardiac index increased by 18 ± 5%. Heart rate, ventricular filling pressures, and whole body oxygen consumption were not affected by adenosine. Despite the reduced mean arterial blood pressure, coronary sinus flow increased by 128 ± 26% (SEM) in parallel with a 96 ± 11% (SEM) increase in coronary sinus oxygen content. Left and right ventricular stroke work indices, as well as myocardial oxygen consumption, were maintained. ECG (12-lead) demonstrated signs of ischemia in one subject, while myocardial lactate uptake was unchanged in all subjects. In conclusion, adenosine-induced hypotension in patients with peripheral vascular disease increased cardiac index without affecting myocardial work, whole body, and myocardial oxygen consumptions. The marked increase in coronary sinus blood flow, indicating coronary vasodilation, was not related to increased myocardial work. Further information regarding myocardial effect of adenosine in patients with ischemic heart disease is warranted.

Incidence of sore throat and patient complaints after intraoperative transesophageal echocardiography during cardiac surgery

To evaluate the incidence of postoperative side effects and patient complaints following transesophageal echocardiography (TEE), 57 patients were interviewed by questionnaire and examined by pharyngeal inspection, preoperatively. The patients were randomized to undergo surgery with or without intraoperative TEE, and a second interview and examination were performed in 48 patients on the second postoperative day using a double-blind protocol. Twenty-four of the patients were investigated by TEE over a period of 5.4 +/- 2.3 hours and 24 had surgery without TEE. The intubation time for the two groups did not differ. There was no difference between controls and TEE patients with regard to painful swallowing evaluated by a visual analog scale. Furthermore, there was no difference between the controls and TEE patients regarding nausea or time elapsed from extubation to the first oral intake. No differences between the groups were found regarding the findings on pharyngeal inspection and no major complication attributable to the use of TEE occurred. A sore throat with painful swallowing was not a great problem for the patients in the present study; this indicates that endotracheal intubation rather than TEE caused the minor complaints. It is concluded that intraoperative TEE can be used without harmful postoperative pharyngeal side effects.

Myocardial outflow of calcitonin gene-related peptide in relation to metabolic stress during coronary artery bypass grafting without cardiopulmonary bypass.

OBJECTIVE Because of adverse effects of cardiopulmonary bypass and the prospect of shortening intensive care and hospital stay, coronary artery bypass grafting without cardiopulmonary bypass is gaining increased attention. The impact of the localized myocardial ischemia that is inherent in these procedures has not been thoroughly investigated in human beings. We have investigated metabolic changes, possible myocardial damage, and myocardial outflow of the vasodilator calcitonin gene-related peptide during coronary artery bypass grafting without cardiopulmonary bypass. METHODS Coronary sinus and arterial blood was sampled before coronary arterial occlusion, after 10 minutes of ischemia, and after 1 and 10 minutes of reperfusion in 9 consecutive patients (mean age 70 +/- 5 years) who had an anastomosis performed to the left anterior descending artery without cardiopulmonary bypass. RESULTS No perioperative myocardial infarctions occurred. The arteriovenous difference in lactate decreased during ischemia, to reach a minimum after 1 minute of reperfusion (-0.17 +/- 0.25 vs 0.15 +/- 0.25 mmol/L before ischemia; P =.008). Myocardial lactate extraction decreased (from 11.2 +/- 13.6 micromol/min before ischemia to -3.0 +/- 7.0 micromol/min after 1 minute of reperfusion; P =.012), that is, a net production of lactate. The arteriovenous difference in calcitonin gene-related peptide decreased from -0.1 +/- 2.6 pmol/L before ischemia to -30.5 +/- 26.5 pmol/L (P =.008) after 1 minute of reperfusion. CONCLUSIONS The localized myocardial ischemia associated with these procedures causes metabolic changes in the myocardium, but no myocardial damage. The ischemia-related outflow of calcitonin gene-related peptide indicates that the vasodilating and cardioprotective properties of this peptide that are known from animal studies may be of importance in myocardial ischemia in human beings.

Inhaled isoflurane sedation during therapeutic hypothermia after cardiac arrest: a case series.

Objective:Therapeutic hypothermia in the ICU requires mechanical ventilation and sedation. Hypothermia reduces the metabolism of commonly used IV sedatives. The use of long-acting sedative agents may confound neurologic assessment. Volatile anesthetics have been reported to provide protection against ischemia-reperfusion injury and have been safely used in the ICU to provide sedation in trials with shorter wake-up times. There are no clinical studies in this setting. We describe a case series and discuss potential benefits. Design:Retrospective study. Settings:Ten-bed ICU, university hospital. Patients:Twelve patients resuscitated from cardiac arrest with Glasgow Coma Scale score less than or equal to 4. Intervention:Isoflurane sedation with the AnaConDa during 24 hours therapeutic hypothermia, until rewarming. Measurements and Main Results:Data were extracted from the computerized ICU chart/monitors, hospital and prehospital charts, and the national death index. Patients were 49–76 years old. Median return of spontaneous circulation was 14 minutes. Glasgow Coma Scale scores were assessed within 24 hours from reaching normal body temperature and compared with outcomes at 6 months: six patients had poor Glasgow Coma Scale scores (< 8) that remained low and all died before 6-month follow-up, whereas another six patients had high scores (> 8) and survived to 6 months with good Cerebral Performance Category. In the ICU, four of the survivors were directly extubated after rewarming while two were once more sedated due to pneumonia requiring invasive ventilator therapy. All patients required norepinephrine to maintain adequate mean arterial pressure. Isoflurane sedation was changed to midazolam in two nonsurviving patients because of hemodynamic instability, which persisted despite the change. Conclusions:Sedation with volatile anesthetics during therapeutic hypothermia may be a feasible short-acting option with potential postconditioning effects protecting vital organs from ischemia-reperfusion injury. Its measurability and insignificant drug accumulation could facilitate early neurologic assessment. Prospective clinical trials are warranted.

Early results with cardiac support device implant in patients with ischemic and non‐ischemic cardiomyopathy

Objective—To evaluate the possible beneficial echocardiographic, functional and quality of life improving effects of passive containment surgery using the CorCap™ Cardiac Support Device in heart failure patients with dilated cardiomyopathy. Design—Eight patients with dilated cardiomyopathy subjected to cardiac surgery received the Cardiac Support Device. Patients with ischemic cardiomyopathy (n = 4) underwent coronary artery bypass surgery receiving one to three bypass grafts. In the idiopathic cardiomyopathy group (n = 4) mitral valve plasty was performed in two patients while two patients received the Cardiac Support Device only. Results—All patients survived the surgery and were discharged to home. There was a gradual, sustained improvement in cardiac dimensions (left ventricular end‐diastolic diameter, left ventricular end‐systolic diameter) and functional improvement (ejection fraction, 6‐min walk, NYHA functional class) as well as quality of life. These beneficial effects developed more rapidly and more extensively in the idiopathic cardiomyopathy group. Conclusion—Addition of the Cardiac Support Device to conventional cardiac surgery, or applied alone, is safe and simple. The device seems to reverse ventricular dilatation and improve functional capacity and well‐being of heart failure patients with dilated cardiomyopathy. Further studies will delineate what patient population will best benefit from passive containment surgery using the CorCap™ Cardiac Support Device.

Metabolic changes induced by ischemia and cardioplegia: a study employing cardiac microdialysis in pigs

OBJECTIVE The present study investigates dynamic changes of myocardial metabolism in response to ischemia, cardioplegia, and extracorporeal circulation (ECC) in order to differentiate between the contributing effects of each of these interventions. Furthermore, warm blood cardioplegia versus empty beating of the heart were compared as methods to resuscitate the ischemic myocardial metabolism. METHODS Swedish Landrace pigs on ECC (ECC) were compared with pigs on ECC with warm ischemic cardiac arrest (ischemia) or on ECC with warm ischemic arrest followed by warm blood cardioplegia (ischemia-cardioplegia), using sham-operated pigs as controls (n=7 in each group). Microdialysis probes were placed on the surface of the left ventricle and in the femoral artery for serial evaluation of metabolites in the intracardiac extracellular fluid and arterial blood. When hearts started in ventricular fibrillation (VF), it was electroconverted after 10 min of normal blood reperfusion. If VF started after 10 min of reperfusion electroconversion was immediately performed. RESULTS There were no differences between groups in arterial contents of serine, citrulline, arginine, inosine, hypoxanthine, guanosine, aspartate, glutamate, pyruvate, or asparagine throughout the observation period. Systemic lactate increased in pigs subjected to ischemia (P<0.001) or ischemia and cardioplegia (P=0.002), highest in the ischemia only group (P=0.002). In left ventricular microdialysates, lactate increased in pigs subjected to ischemia alone (P<0.001 vs. ECC) and ischemia and cardioplegia (P=0.004 vs. ECC). Guanosine increased in ischemia versus ECC (P=0.002), while hypoxanthine was increased in microdialysates of both ischemic (P=0.002) and ischemic-cardioplegic (P=0.001) pig hearts. Inosine was increased in pigs subjected to ischemia and cardioplegia (P<0.001 vs. ECC). All ischemic hearts started with VF, but while in the warm ischemia group VF started within 10 min of reperfusion, the ischemia-cardioplegia group had a longer asystolia with VF starting 11-22 min of blood reperfusion. CONCLUSION The heart should be allowed to start empty beating rather than by the use of warm continuous blood cardioplegia. Microdialysis and sampling of interstitial metabolites may be advantageous when an increased sensitivity is needed or when repeated blood sampling is difficult or contraindicated in monitoring of the myocardium.