Ragnar Hotvedt

Prehospital advanced life support provided by specially trained physicians: is there a benefit in terms of life years gained?

Background:  The benefit of prehospital advanced life support (ALS) is disputed, as is the prehospital use of specially trained, hospital‐based physicians. The purpose of the study was to assess the health benefit from an anesthesiologist‐manned prehospital emergency medical service (EMS), and to separate the benefit of the anesthesiologist from that of rapid transport.

Cardiac electrophysiologic and hemodynamic effects related to plasma levels of bupivacaine in the dog.

To investigate electrophysiologic and hemodynamic responses to various plasma levels of bupivacaine, especially those in the range normally seen during regional anesthesia, bupivacaine was given intravenously as a bolus dose followed by continuous infusion in pentobarbital-anesthetized dogs. Cardiac electrophysiology was studied by His bundle electrography, programmed electrical stimulation, and monophasic action potential recordings. At plasma bupivacaine concentrations below 1000 ng/ml, no significant electrophysiologic or hemodynamic effects were observed. This indicates that systemic responses to absorbed bupivacaine do not contribute to the cardiac electrophysiologic effects recently demonstrated during thoracic epidural analgesia. At a plasma level of about 2000 ng/ml, a level occasionally achieved during regional anesthesia, bupivacaine prolonged impulse conduction time in all parts of the heart, prolonged atrial and AV nodal refractoriness, decreased left ventricular inotropy, but had no effect on ventricular refractoriness or monophasic action potential duration. These electrophysiologic effects may enhance susceptibility to reentrant arrhythmias.

Pentobarbital Plasma Concentrations and Cardiac Electrophysiology During Prolonged Pentobarbital Infusion Anaesthesia in the Dog

There is need for a prolonged stable level of anaesthesia, and we therefore investigated the cardiac electrophysiological effects of continuous pentobarbital infusion after initial pentobarbital injection to induce anaesthesia in dogs. Plasma concentrations of pentobarbital were measured by gas‐liquid chromatography. Heart rate, atrial, atrioventricular (AV) nodal and His‐Purkinje conduction times were measured by His bundle electrography, and atrial, AV nodal and ventricular refractoriness by programmed electrical stimulation. Over a 5‐h observation period, continuous infusion of pentobarbital 3.5 mg · kg‐1 h‐1 after an initial pentobarbital injection of 25 mg · kg‐1 intravenously gave stable mean plasma concentrations of 140‐135 μmol · l‐1. The cardiac electrophysiological variables studied did not change significantly during this period. We conclude that a stable experimental model for cardiac electrophysiological studies can be obtained for several hours by‐continuous pentobarbital infusion.

Class III antiarrhythmic action linked with positive inotropy: antiarrhythmic, electrophysiological, and hemodynamic effects of the sea-anemone polypeptide ATX II in the dog heart in situ.

Summary: Most antiarrhythmic drugs are more or less negatively inotropic. Positively inotropic properties, however, have been demonstrated for some class III antiarrhythmic drugs. To test the hypothesis that class III antiarrhythmic effect and positive inotropy may be linked, we used the sea-anemone polypeptide ATX II, which in isolated heart muscle preparations has been shown to specifically inhibit the inactivation of the sodium channel and thereby increase action potential duration and inotropy. We used 12 pentobarbital-anesthetized dogs. Atrial arrhythmias were induced by high-rate stimulation of the right atrium in 5 dogs. Cardiac electro-physiological effects were studied by His-bundle electrography, programmed electrical stimulation, and monophasic action potential (MAP) recordings in 7 autonomically blocked dogs. ATX II (1.0–5.0 μg/kg i.v.) converted the arrhythmias, and in the autonomically blocked dogs markedly increased atrial and ventricular refractoriness and ventricular MAP duration without influencing atrial or ventricular conduction velocities, heart rate, or AV-nodal refractoriness. ATX II induced a marked increase in left ventricular dP/dt max. The study indicates that ATX II has class III antiarrhythmic effect, and that the electrophysiological and positive inotropic effects of ATX II have a common mechanism.

Cardiac electrophysiological and hemodynamic effects of beta-adrenoceptor blockade and thoracic epidural analgesia in the dog.

To investigate whether thoracic epidural analgesia (TEA) has additional cardiac electrophysiological and hemodynamic effects when induced after β-adrenergic blockade, bupivacaine (0.7–1.2 mg/kg) was injected into the epidural space at T2–3 after intravenous injection of atenolol (1.0 mg/kg) in anesthetized dogs. Cardiac electrophysiology was studied by His bundle electrography, programmed electrical stimulation, and monophasic action potential recordings. Atenolol reduced heart rate, prolonged atrio-ventricular (AV) nodal impulse conduction time and refractoriness, prolonged ventricular refractoriness and action potential duration, and decreased left ventricular (LV) dP/dt max. Addition of TEA further reduced heart rate, prolonged AV nodal conduction time and refractoriness, decreased LV dP/dt max and arterial blood pressure, but had no effect on atrial and ventricular electrophysiology. Induction of TEA during β-blockade may thus have additive depressive effects on sinoatrial and AV nodal functions, as well as on left ventricular inotropy. The study indicates that the cardiac electrophysiological effects induced by TEA are mainly caused by decreased β-receptor stimulation, but increased vagal activity may also contribute.

Effects of Thoracic Epidural Analgesia on Cardiovascular Function and Plasma Concentration of Free Fatty Acids and Catecholamines in the Dog

Increased plasma levels of free fatty acids (FFA), leading to increases in the myocardial oxygen demand, are seen after, for example, surgical stress, traumas and myocardial infarction. The present study was undertaken to investigate the cardiovascular effects of thoracic epidural analgesia (TEA) and the effect of TEA on the plasma concentration of FFA and catecholamines. In 10 sodium‐pentobarbital‐anaesthetized dogs the local anaesthetic agent bupivacaine was injected into the thoracic epidural space via a surgically introduced catheter. TEA markedly reduced heart rate, mean aortic blood pressure, left ventricular systolic blood pressure and dP/dtmax. TEA reduced the plasma concentration of FFA. The FFA‐lowering effect was greatest when the FFA values were high. The effect of TEA on the plasma concentration of noradrenaline and adrenaline was inconsistent and seemed to be of minor importance for the haemodynamic and FFA effects of TEA. The study indicates that TEA, by its haemodynamic and FFA‐lowering effects, may reduce myocardial oxygen demand.

Cardiac effects of thoracic epidural morphine caused by increased vagal activity in the dog

This study was carried out in order to investigate possible side‐effects of thoracic epidural morphine on cardiac electrophysiology, haemodynamics and metabolism. In pentobarbital‐anaesthetized dogs, intracardiac conduction times were determined by His bundle electrography, and refractoriness by programmed electrical stimulation; monophasic action potential recordings were obtained from the right ventricle by the suction electrode technique. Cardiac output, left ventricular and aortic blood pressures were measured, as well as plasma concentrations of morphine, free fatty acids, glycerol, glucose and lactate. Thoracic epidural morphine (0.12 mg‐kg‐1) reduced spontaneous heart rate, prolonged atrioventricular nodal conduction time and refractoriness, and reduced left ventricular dP/dt max. Bilateral vagotomy reversed these effects. Intraatrial, His Purkinje and intraventricular conduction times, atrial and ventricular refractoriness and action potential duration, stroke volume and mean aortic blood pressure, as well as the metabolic variables, were not significantly influenced by thoracic epidural morphine with or without vagotomy. Peak plasma morphine levels of 12–25 ng‐ml‐1 were measured 10 min after morphine injection. In conclusion, this study demonstrates depressive side‐effects of epidural morphine on cardiac function, mediated by an increased vagal activity.

Threats from patients and their effects on medical decision making: a cross-sectional, randomised trial

BACKGROUND Negative experiences are not uncommon among doctors in Norway. Our aim was to find out about the various types of negative reactions (eg, complaints, negative exposure to the media, financial claims, and notification to the police) received by physicians from patients or relatives in response to treatment, to identify their cause, and to study their effects on subsequent clinical decisions. METHODS We posted questionnaires about negative reactions of patients to a random sample (n=1260) of Norwegian doctors. Each doctor was additionally sent five written case simulations and asked to choose one of several proposed clinical strategies. Half (630) the physicians received cases containing threats from the patient or their relatives. FINDINGS 988 (78%) physicians returned the questionnaire, 463 (47%) of whom reported negative experiences. Such experiences were reported more frequently by men (357 [51%]) and family physicians (157 [58%]) than by other participants. Negative experiences did not affect choice of strategy for case simulations. For the first case, chest pain, 217 (44%) physicians presented with a threat chose a defensive strategy compared with 145 (30%) of those who were not (difference 14%; 95% CI 8-20). For the second case, a headache case, the corresponding numbers were 278 (57%) and 118 (25%) (32%; 26-38). Physician age, sex, specialty, or experience of negative reactions of patients did not alter the effect of threats received during our study. INTERPRETATION Negative experiences do not affect subsequent decision making. However, doctors do comply with wishes from patients or relatives when presented with direct threats.

Doctors are to blame for perceived medical adverse events. A cross sectional population study. The Tromsø study

BackgroundMost current knowledge of the incidence of medical adverse events (AEs) comes from studies carried out in hospital settings. Little is known about AEs occurring outside hospitals, in spite the fact that most of contacts between patients and health care take place in primary care. Small sample population studies report that 4–49% of the general public have experienced AEs related to their own or family members´ care.The purpose with the present study was to investigate the occurrence of experienced medical adverse events in a large general population.MethodsWe invited 19763 inhabitants of a municipality in northern Norway, age 30 years and older, to fill in a questionnaire. Main outcome measures were life time prevalence of AEs experienced by respondents or their first degree relatives, perceived responsibility for and predictors of such events, as well as formal complaints as a reaction to the events.ResultsThe response rate was 66%. Nine and 10% of the respondents reported self-experienced adverse events, and 15 and 19% (men and women, respectively) that their relatives had experienced AEs. Logistic regression models showed that the strongest predictors of reporting self-experienced adverse events were: Having been persuaded to accept an unwanted examination or treatment, difficulties in getting a referral from primary to specialist health care, and inadequate communication with the doctor. Of the respondents who had experienced adverse events personally, 62% placed the responsibility for the event on the general practitioner, 39% on the hospital doctor, and 19% on failing routines or cooperation. Only 7% of men and 14% of women who reported self-experienced events handed in a formal complaint.ConclusionsThe public predominantly place the responsibility for medical adverse events on doctors, in particular general practitioners, and to a lesser degree on the system. This should be emphasised by doctors and managers who communicate with patients who have experienced AEs, and in patient safety work. Only a small fraction of adverse events results in a formal written complaint. Therefore, such complaints are of limited value as a basis for patient safety work.

Are expert panel judgments of medical benefits reliable? An evaluation of emergency medical service programs.

OBJECTIVE We have used multidisciplinary expert panels to assess the health benefits from two different emergency medical service programs in Norway. This gave the opportunity to study the reliability of the expert panel method. METHODS Two panels assessed case reports for 18 children, and two other panels assessed case reports for 64 adult patients. The assessments of each case report were compared. These assessments were also compared with assessments of the same case reports, done by the same panels 1 and 9 years earlier. RESULTS Two different panels agreed on the benefit/no benefit conclusion in at least 75% of the patients, both for children and adult patients (kappa 0.88-0.50). For groups of patients assessed to have some health benefit, the magnitude of the benefit estimates differed by 25% between the panels. When the same panels assessed the same patient groups twice, 1 and 9 years apart, their estimates of total benefit differed up to 30%. However, estimates for single patients, as well as estimates from single panel members, varied considerably more. CONCLUSIONS Use of multidisciplinary expert panels is a useful method for estimating health benefits on program level or for groups of patients. But assessments from single panelists, and for single patients may be seriously biased.