Ulrich Bothner

Large-Dose Administration of 6% Hydroxyethyl Starch 200/0.5 for Total Hip Arthroplasty: Plasma Homeostasis, Hemostasis, and Renal Function Compared to Use of 5% Human Albumin

Within a daily dose of 20 mL/kg, medium-molecular hydroxyethyl starch (HES) is a safe and effective colloid for intravascular blood volume replacement. The effect of large doses on coagulation and renal function is unknown. We prospectively studied 41 patients undergoing total hip arthroplasty during the perioperative period. Inevitable blood loss was replaced with HES (HES group) or albumin (ALB group) in combination with packed red blood cells (PRBC), fresh frozen plasma (FFP), and platelets. Hemodynamic, oncotic, coagulation, and renal functions were compared initially, at the end of surgery, during the postoperative period (1, 3, and 6 h), and also with respect to the volume of colloid solution administered (1500, 2000, and 3000 mL). Total intake and output balances, as well as the costs of blood replacement therapy, were registered at the end of the study. We found differences in oncotic variables even at 6 h after surgery (total serum proteins [TSP]: HES 36.4 +/- 7.9 g/L versus ALB 55.6 +/- 6.1 g/L, P < 0.01; serum albumin: HES 25.5 +/- 5.3 g/L versus ALB 42.0 +/- 5.6 g/L, P < 0.01). Colloid osmotic pressure (COP) and hemodynamic, coagulation, and renal functions were comparable, as was total blood loss (HES 4247 +/- 2090 mL versus ALB 4051 +/- 2830 mL). Total requirements for colloid solutions (HES 35.9 +/- 7.4 mL/kg versus ALB 33.9 +/- 10.5 mL/kg), PRBC, FFP, or platelets were comparable, whereas total cost of blood replacement therapy was 33% less in the HES group. With respect to efficacy and side effects on coagulation and renal function, medium molecular HES is an appropriate and economic alternative to albumin at daily doses of up to at least 36 mL/kg. (Anesth Analg 1996;83:262-8)

The performance of electroencephalogram bispectral index and auditory evoked potential index to predict loss of consciousness during propofol infusion.

UNLABELLED The bispectral index (BIS) of the electroencephalogram and middle latency auditory evoked potentials are likely candidates to measure the level of unconsciousness and, thus, may improve the early recovery profile. We prospectively investigated the predictive performance of both measures to distinguish between the conscious and unconscious state. Twelve patients undergoing lower limb orthopedic surgery during regional anesthesia additionally received propofol by target-controlled infusion for sedation. The electroencephalogram BIS and the auditory evoked potential index (AEPi), a mathematical derivative of the morphology of the auditory evoked potential waveform, were recorded simultaneously in all patients during repeated transitions from consciousness to unconsciousness. Logistic regression procedures, receiver operating characteristic analysis, and sensitivity and specificity were used to compare predictive ability of both indices. In the logistic regression models, both the BIS and AEPi were significant predictors of unconsciousness (P < 0.0001). The area under the receiver operating characteristic curve for discrete descending index threshold values was apparently, but not significantly (P > 0.05), larger for the AEPi (0.968) than for the BIS (0.922), indicating a trend of better discriminatory performance. We conclude that both the BIS and AEPi are reliable means for monitoring the level of unconsciousness during propofol infusion. However, AEPi proved to offer more discriminatory power in the individual patient. IMPLICATIONS Both the bispectral index of the electroencephalogram and the auditory evoked potentials index are good predictors of the level of sedation and unconsciousness during propofol infusion. However, the auditory evoked potentials index offers better discriminatory power in describing the transition from the conscious to the unconscious state in the individual patient.

Perioperative respiratory events in smokers and nonsmokers undergoing general anaesthesia

Background: The prevalence of respiratory diseases in smokers and nonsmokers and the incidence of perioperative respiratory events (PREs) were investigated for patients undergoing general anaesthesia. The aim was to quantify well‐known problems and to identify possible new associations between smoking and PREs.

Assessment of the safety and tolerance of 6% hydroxyethyl starch (200/0.5) solution : A randomized, controlled epidemiology study

None of the natural and synthetic colloids currently available is free from the risk of side effects.This study was performed to contribute to the epidemiology of adverse reactions of the widely used 200/0.5 hydroxyethyl starch 6% solution (HES). Study end points were anaphylactoid reactions during preanesthesia infusion and perioperative course, and pruritus 5 days postoperatively (clinical examination and inquiry) and 8 wk after application (mailed patient questionnaire). We consecutively randomized 750 patients undergoing minor elective surgery into two parallel groups treated with HES (from two different manufacturers) and one control group treated with lactated Ringers solution. The study population was well matched among the groups and consisted of patients of both sexes, aged 18-95 yr, ASA physical status I-III. No drug-related anaphylactoid reactions were detected during either of the observation intervals. There was no episode of pruritus after the fifth postoperative day. Incidence of pruritus after 8 wk was quite frequent but not significantly different (chi squared test, P = 0.77): 9.1% and 12.0% in the two HES groups and 11.5% in the lactated Ringers solution control group. Except for pruritis, we conclude that HES was associated with no more complications than lactated Ringers solution. Implications: Anaphylactoid reactions and pruritus (itching) after the administration of a 6% hydroxyethyl starch (200/0.5) versus lactated Ringers solution were assessed in a prospective, randomized, controlled study. There were no differences, although there was a more than 10% incidence of pruritus in both groups. (Anesth Analg 1998;86:850-5)

EFFECTS OF EPINEPHRINE AND VASOPRESSIN ON MEDIAN FIBRILLATION FREQUENCY AND DEFIBRILLATION SUCCESS IN A PORCINE MODEL OF CARDIOPULMONARY RESUSCITATION

OBJECTIVE This study was designed to assess whether median frequency of ventricular fibrillation (VF) correlates with myocardial blood flow and defibrillation success during cardiopulmonary resuscitation (CPR) after epinephrine or vasopressin administration. METHODS AND RESULTS After 4 min of VF and 3 min of CPR, 14 pigs received 0.045 mg/kg epinephrine or 0.4 U/kg vasopressin. Using radio-labeled microspheres, median myocardial blood flow during CPR before, and 90 s and 5 min after drug administration (DA) was 15.5 (12.6, 23.1; 25th percentile, 75th percentile), 26.4 (18.5, 29.1), 16.9 (14.9, 19.1) mL min-1 100 g-1, respectively, in the epinephrine, and 16.9 (15.4, 18.9), 48.1 (36.9, 68.9) (P < 0.05 vs. before DA), 52.3 (38.5, 65.0) mL min-1 100 g-1, respectively, in the vasopressin group. Using spectral analysis of VF, median frequency of VF was 11.0 (10.7, 11.8), 11.3 (9.6, 13.1), 10.2, (8.8, 11.4) Hz, respectively, in the epinephrine, and 10.1 (10.0, 10.5), 11.7 (11.1, 14.2) (P < 0.05 vs. before DA), 13.2 (11.5, 13.9) Hz, respectively, in the vasopressin group at the same points in time. Median frequency correlates significantly with myocardial blood flow in the epinephrine (n = 21); rs = 0.772; P < 0.001) and in the vasopressin group (n = 21; rs = 0.905; P < 0.001). Median fibrillation frequency before the first defibrillation was 13.0 (12.2, 13.2) Hz in resuscitated (n = 8) and 9.2 (8.3, 10.2) Hz (n = 6) in non-resuscitated animals (P < 0.01). CONCLUSIONS We conclude that median frequency of VF reflects myocardial blood flow and the chance of successful defibrillation during closed-chest CPR after vasopressor treatment in a porcine model of VF.

Effects of graded doses of vasopressin on median fibrillation frequency in a porcine model of cardiopulmonary resuscitation: results of a prospective, randomized, controlled trial.

OBJECTIVE To assess the effects of graded doses of vasopressin vs. saline on median fibrillation frequency and defibrillation success in a porcine model of cardiopulmonary resuscitation. DESIGN Prospective, randomized, controlled trial. SETTING Animal laboratory in a university medical center. SUBJECTS Twenty-eight domestic pigs (body weight between 26 and 31 kg), aged 12 to 14 wks. INTERVENTIONS AND MAIN RESULTS After 4 mins of ventricular fibrillation and 3 mins of closed-chest cardiopulmonary resuscitation, the animals were allocated to receive either 0.2 U/kg of vasopressin (n = 7), 0.4 U/kg of vasopressin (n = 7), 0.8 U/kg of vasopressin (n = 7), or 10 mL of saline (n = 7, control group). Using radiolabeled microspheres, myocardial blood flow rates during cardiopulmonary resuscitation-before drug administration and 90 secs and 5 mins after drug administration-were as follows in the four groups (mean +/- SEM): 18.8 +/- 0.9, 17.2 +/- 1.1, and 14.6 +/- 1.4 mL/min/100 g in the control group; 17.8 +/- 2.2, 49.6 +/- 6.3 (p < .01 vs. control group), and 29.4 +/- 3.1 mL/min/100 g (p < .05 vs. control group) in the group receiving 0.2 U/kg of vasopressin; 17.1 +/- 1.0, 52.4 +/- 7.5 (p < .01 vs. control group), and 52.2 +/- 5.8 mL/min/100 g (p < .001 vs. control group) in the group receiving 0.4 U/kg of vasopressin; and 18.1 +/- 1.6, 94.9 +/- 9.2 (p < .001 vs. control group), and 57.2 +/- 6.3 mL/min/100 g (p < .001 vs. control group) in the group receiving 0.8 U/kg of vasopressin. Using spectral analysis, median frequencies of ventricular fibrillation-before drug administration and 90 secs and 5 mins after drug administration-were as follows in the four groups: 9.6 +/- 0.4, 8.5 +/- 0.8, and 7.2 +/- 1.0 Hz in the control group; 9.7 +/- 0.5, 12.9 +/- 0.8 (p < .01 vs. control group), and 12.7 +/- 0.8 Hz (p < .001 vs. control group) in the group receiving 0.2 U/kg of vasopressin; 10.3 +/- 0.2, 12.7 +/- 0.9 (p < .01 vs. control group), and 12.8 +/- 0.7 Hz (p < .001 vs. control group) in the group receiving 0.4 U/kg of vasopressin; and 10.0 +/- 0.9, 14.1 +/- 0.9 (p < .001 vs. control group), and 12.5 +/- 0.9 Hz (p < .001 vs. control group) in the group receiving 0.8 U/kg of vasopressin at the same points in time. Median frequency before the first defibrillation attempt was 12.3 +/- 0.4 Hz in the resuscitated animals (n = 19) and 8.2 +/- 1.2 Hz in the nonresuscitated animals (n = 9) (p < .001). CONCLUSIONS This study contributes to the characterization of the effect of increasing global myocardial blood flow on median fibrillation frequency after administration of graded doses of vasopressin in a porcine model of ventricular fibrillation. Interventions such as vasopressor treatment that increase fibrillation frequency improve the chance of successful defibrillation.

Clinical utility of EEG parameters to predict loss of consciousness and response to skin incision during total intravenous anaesthesia

We studied 30 female patients undergoing elective surgery, to assess the reliability of electroencephalogram spectral edge frequency and median frequency to predict loss of consciousness and movement in response to skin incision during total intravenous anaesthesia. Each patient received a different combination of propofol (1, 2, 3, 4, 5 or 6 μgml−1) and sufentanil (0.1, 0.2, 0.3, 0.5 or 1.0 ngml−1) target concentrations for induction of anaesthesia using target controlled infusions, assigned randomly. In a logistic regression model, spectral edge frequency was a significant determinant of both loss of consciousness (p = 0.0006) and movement to skin incision (p = 0.0044), whereas for median frequency no significant prediction model could be established. The probabilities of 50% and 95% no response for spectral edge frequency were 13.4 Hz and 6.8 Hz, respectively. The variability of the data limited the predictive value, so that spectral edge frequency was a poor predictor and median frequency was no predictor of response in the individual patient during total intravenous propofol/sufentanil anaesthesia.

The impact of minor perioperative anesthesia-related incidents, events, and complications on postanesthesia care unit utilization.

UNLABELLED The German Society of Anesthesiology and Intensive Care Medicine evaluates the standardized and routine reporting of perioperative anesthesia-related incidents, events, and complications (IEC). As part of the long-term projects definitions, IECs are graded according to severity and to their clinical consequence on further postanesthesia monitoring and treatment demands. The adult study population of our department comprised 37,079 patients recovering from anesthesia in a tertiary university hospital from July 1992 through June 1997. Cardiac, obstetric, craniotomy, thoracotomy, laparotomy, and emergency operations were excluded. Multivariate regression statistics were used to calibrate the impact of minor graded IECs on necessary postanesthesia care unit (PACU) utilization. Minor and severe IECs appeared in 22.1% and 0.2% of the patients. A minor IEC occurrence was a statistically significant (P < 0.001) predictor of PACU utilization in a multivariate regression model. The mean difference of PACU length of stay for patients with minor IECs was prolonged by a range of 6%-26% when adjusted for coexisting severity features such as age, gender, ASA physical status, and type and duration of anesthesia and surgery. We conclude that the IEC methodology integrates epidemiologic information about perioperative anesthesia outcome. Minor but frequently occurring IECs have an impact on PACU utilization and are thus important to measure and follow. IMPLICATIONS It is desirable to know how anesthesia-related incidents, events, and complications influence postanesthesia care. Analyses of standardized and routine perioperative outcome data, as proposed by the German anesthesia quality project, can show that even minor events consume relevant resources and are thus important to measure and follow.

Concentrations of prolactin and prostaglandins during and after cardiopulmonary resuscitation.

OBJECTIVES To assess differences in plasma prolactin and prostaglandin concentrations in resuscitated and nonresuscitated patients during cardiopulmonary resuscitation (CPR), and to compare changes of prostaglandin and prolactin concentrations with hemodynamic variables in the immediate postresuscitation phase. DESIGN Prospective, descriptive study. SETTING Emergency medical service at a university hospital. PATIENTS Twenty-nine patients ranging in age from 39 to 87 yrs with out-of-hospital cardiac arrest. INTERVENTIONS Venous blood samples were taken during CPR and at 5, 15, 30, and 60 mins after restoration of spontaneous circulation in order to measure plasma concentrations of prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 by immunoassay. Heart rate and blood pressure were measured at 5, 15, 30, and 60 mins after restoration of spontaneous circulation. MEASUREMENTS AND MAIN RESULTS In 15 patients, restoration of spontaneous circulation was achieved; in the remaining 14 patients, successful resuscitation was not possible. During CPR, the mean plasma prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 concentrations were 95.9 +/- 13.6 micrograms/L, 357 +/- 61 ng/L, 228 +/- 28 ng/L, 277 +/- 66 ng/L, and 375 +/- 78 ng/L, respectively, in resuscitated patients, and 23.9 +/- 5.6 micrograms/L (p = .0001), 192 +/- 22 ng/L (p = .005), 202 +/- 31 ng/L (p = .528), 221 +/- 40 ng/L (p = .713), and 344 +/- 77 ng/L (p = .780), respectively, in nonresuscitated patients. At 60 mins after restoration of spontaneous circulation, the mean plasma prolactin, prostaglandin F2 alpha, 15-keto-13,14-dihydro-prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 concentrations were 50.1 +/- 9.5 micrograms/L, 306 +/- 42 ng/L, 503 +/- 87 ng/L, 278 +/- 55 ng/L, and 355 +/- 30 ng/L, respectively. Mean values of systolic arterial blood pressure were 114 +/- 12 mm Hg at 30 mins and 123 +/- 18 mm Hg at 60 mins. No significant correlations were found between hemodynamic values and plasma concentrations of prolactin or prostaglandins. CONCLUSIONS Prolactin and prostaglandin concentrations were increased during cardiac arrest and CPR. Successful initial resuscitation was associated with increased prolactin and prostaglandin F2 alpha concentrations during CPR. Decreased concentrations in non-resuscitated patients may have been a result of exhaustion of the neuroendocrine and eicosanoid systems, or may be due to differences in bioavailability at the site of blood sampling based upon differences in hemodynamics.

Validation of Routine Incidence Reporting of One Anaesthesia Provider Institution Within a Nation-wide Quality of Process Assessment Program

In 1992, a long-term project was launched by the German Society for Anaesthesiology and Intensive Care Medicine to render quality comparisons between anaesthesia providers. As one of the first volunteer centres, we established the standardised reporting of perioperative anaesthesia related incidents, events, and complications (IEC) in any routine anaesthetic procedure performed. This present study is aimed to explore the longitudinal stability of IEC recordings in one institution, which should be a prerequisite for valid external comparisons. Methods. The analyses were completed on an adult population of 49945 consecutive anaesthetic procedures with peripheral surgery from July 1992 until December 1996. Attribute quality control charts with monthly samples of an average of 954 anaesthetics were used to assess statistical variability of specific IEC incidences. Results. Average proportions were 20% for moderate IEC, 2.7% for severe IEC, 13% for moderate cardio-vascular IEC, 1.3% for severe cardio-vascular IEC, and 2.4% for respiratory IEC. Moderate IEC proportions showed considerable variability during the study period. A series of excess proportions was probably due to educational activities on documentation discipline. In contrast, clinically severe IEC proportions were rather stable. Stability of cardio-vascular IEC porportions resembled the picture of the overall IEC assessment. Monthly respiratory IEC proportions showed smallest variability during the study period. Discussion. Use of the quality control statistics is suitable to distinguish random from systematic influence on quality indicators. IEC recordings that are not specific in pathophysiologic type or are of low grade of clinical severity, are heavily dependent on systematic documentation features. We assume that peak values, such as in times of optimised documentation discipline, better reflect reality than average values because missing reporting is much more likely than false positives.