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Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 307 records · Page 17Linked to original sources
PubMed1993

[The effect of flumazenil on the endocrine stress reaction following modified neuroleptanesthesia].

This study was undertaken to investigate in a prospective randomized way the influence of the benzodiazepine antagonist flumazenil on endocrine stress response and haemodynamic parameters after modified neuroleptanaesthesia. A total of 24 patients (ASA scores I or II) aged between 18 and 60 who were scheduled for major gynaecological surgery, were investigated. For modified neuroleptanaesthesia, midazolam, fentanyl and vecuronium were administered in standardized doses. After extubation, patients of the flumazenil group received initial injections of 0.2 mg flumazenil to antagonize the residual effect of midazolam and additional doses of 0.1 mg per minute until the desired level of vigilance was reached (awareness of person, time and place). In the control group no flumazenil was used. Endocrine stress parameters and haemodynamic parameters were measured at 7 different times, from before induction of anaesthesia up to 60 minutes after the operation. In both groups, a marked increase in endocrine stress response was observed. Adrenaline, noradrenaline, antidiuretic hormone, adrenocorticotropic hormone, cortisol, glucose and lactate, however, were not additionally influenced by the antagonism. No influence of flumazenil on mean arterial pressure, heart rate and arterial oxygen saturation was observed. After modified neuroleptanaesthesia, a careful antagonism of midazolam with small doses of flumazenil is not disadvantageous with respect of endocrine stress response and haemodynamic reactions.

Adolescent↗
PubMed1993

[Endocrine and hemodynamic effects of naloxone following modified neuroleptanesthesia].

This study was undertaken to investigate the influence of the opiate-antagonist naloxone on the endocrine stress response and haemodynamic parameters after modified neuroleptanaesthesia in a randomized, prospective design. A total number of 22 patients (ASA-scores I or II) between 18 and 60 years scheduled for major gynaecologic surgery were included. For modified neuroleptanaesthesia, midazolam, fentanyl and vecuronium were administered in standardized doses. After extubation, patients of the naloxone-group received injections of 2 x 0.1 mg naloxone; in controls, no naloxone was used. Endocrine stress parameters and haemodynamic parameters were measured 7 times before induction of anaesthesia and up to 60 minutes after the operation. In both groups, remarkable increases in adrenaline, noradrenaline, antidiuretic hormone, adrenocorticotropic hormone, cortisol, glucose and lactate took place in the postoperative period. This stress response was comparable in both groups and not increased by naloxone. No significant influence of naloxone on mean arterial pressure, heart rate and arterial oxygen saturation was observed. After neuroleptanaesthesia, a careful opiate antagonism with small doses of naloxone is not disadvantageous with respect to endocrine stress response and haemodynamic reactions.

Adolescent↗
PubMed1993

[Cardiac protection in heart surgery interventions by preventive drug administration before extracorporeal circulation. Studies with troponin T as a parameter for perioperative myocardial damage].

The present study was designed to test if prophylactic intravenous nifedipine or nitroglycerine could reduce myocardial damage after cardiopulmonary bypass. 45 patients scheduled for elective coronary artery bypass grafting were divided at random into three groups: Group 1: control; group 2: nifedipine (0.25 microgram/kg/min); group 3: nitroglycerine (1.5 micrograms/kg/min). Infusion period reached from the beginning of anaesthesia until crossclamp of the aorta. Myocardial damage was estimated by troponin T (TnT), CK-MB and ST-segment analysis of the ECG. TnT is a cardiospecific protein from the contractile apparatus of striated muscle cells. TnT-levels might provide a very sensitive marker of small amounts of cardiac muscle necrosis. It was tested with an ELISA/one-step sandwich-assay with streptavidin-technology [9]. Criteria for ischemia in the ST-segment analysis were (according to Smith et al. [19]): ST-depression > 1 mm from baseline or ST-elevation > 2 mm from baseline at J-point + 60 ms. Statistical interpretation was done by one- and two-factorial analyses of variance (including multivariate analyses of variance). Correlation between two variables was tested by regression analysis. A level of p < 0.05 was taken for indicating statistical significance. Biometrical data, circulation data and data from cardiopulmonary bypass were without significant differences among all groups (Tables 1 and 2). Starting from normal values (< 0.05 ng/ml) TnT significantly rose in all groups immediately after cardiopulmonary bypass and remained elevated until the forth day after operation (values between 0.4 and 0.6 microgram/ml) (Figure 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

[A difficult intubation: prolapse of the epiglottis into the trachea in an infant].

Luxation of the epiglottic cartilage is a very uncommon complication of endotracheal intubation in paediatric anaesthesia. We report on a case of prolapse of the epiglottic cartilage into the trachea in a 4-month-old child who had been anaesthetized for palliative banding of the pulmonary artery and correction of a coarctation of the aorta. Further malformations included a single ventricle combined with an ASD II and VSD. The first intubation (ID 3.5 mm) via the nasopharyngeal route seemed not to involve any problems; breathing pressure, however, increased to 25 cm H2O. Direct laryngoscopy after extubation of the smaller tube and insertion of another one (ID 4.0 mm) demonstrated a completely blocked trachea. The epiglottidean cartilage had prolapsed into the tracheal lumen and excluded any possibility of ventilating the patient. After seizing the epiglottic cartilage with a Magill forceps it was possible to pull the cartilage out of the trachea and to intubate again with the 4.0 mm tube. There were no complications in the postoperative period.

Epiglottis↗
PubMed1993

[The effect of different autotransfusion procedures on the antibiotic picture. A study on cephalosporin cefamandole].

Infection after open heart surgery is a serious complication since eradication of infection in these cases is difficult even with appropriate antibiotic therapy. In the attempt to avoid this problem, prophylactic administration of antibiotics is common. Their relative safety and their broad spectrum of activity make cephalosporin antibiotics popular choices for prophylaxis prior to and during operations, including cardiovascular procedures. METHODS. Preoperative antibiotic prophylaxis with 2 g cefamandole was performed in a prospective randomized study including 62 male patients divided into three groups. All patients gave informed consent, and the study was approved by the ethics committee of the hospital. Patients in group 1 (n = 21) and group 2 (n = 21) underwent aortocoronary bypass (ACVB) with extracorporeal circulation (ECC), while patients in group 3 (n = 20) had carotid surgery. Anaesthesia, coronary-bypass procedures and infusion regime were standardized. The flow rate during ECC was maintained at 2.41/min/m2 and the rectal temperature between 33 degrees and 34 degrees C. Arterial and urine specimens for the determination of plasma and urine levels of cefamandole were taken at definite times. Autologous blood salvage during operation was performed with haemofiltration techniques (HF) in group 1 (HF 80, Fresenius, Bad Homburg, Germany) and with cell separation techniques (CS) in group 2 (Hemonetics III, Hemonetics). Plasma and urine cefamandole levels were measured by high-pressure liquid chromatography (HPLC). RESULTS. After administration of 2 g cefamandole mean peak levels of 404.6 +/- 141.7 micrograms/ml were seen. Because of haemodilution at the beginning of extracorporeal circulation, group 1 and 2 showed much lower cefamandole plasma levels, 22.1 +/- 11.6 micrograms/ml and 24.3 +/- 14.4 micrograms/ml, than group 3 (after the same time course), with 47.4 +/- 19.1 micrograms/ml. For all patients in group 1 and 2 prebypass time (70.3 +/- 22.4 min) and the duration of the ECC (72.3 +/- 17.7 min) were comparable. There was a significant correlation between prebypass time and cefamandole plasma levels at the beginning of extracorporeal circulation (P < 0.001). No correlation could be seen for the plasma concentration after discontinuation of the extracorporeal circulation and the duration of extracorporeal circulation. The volume of autologous red packed cells and the enclosed amount of cefamandole showed a significant difference (P < 0.001) between group 1 (1120.0 +/- 296.8 ml, 27.5 +/- 17.1 mg) and group 2 (734.3 +/- 186.6 ml, 2.9 +/- 3.2 mg). The plasma cefamandole level after transfusion of autologous blood displayed a significant correlation (p < 0.01) with cefamandole concentration in the autologous red packed cells. Transfusion of the autologous blood produced no significant increase in plasma cefamandole levels. With an operation time of more than 2.5 h during ECC the cefamandole plasma level decreased below the necessary minimal inhibitory concentration (MIC90), particularly for gram-negative bacteria. CONCLUSION. Additional administration of 1 g cefamandole shortly before the beginning of cardiopulmonary bypass is recommended, particularly for surgical procedures with ECC of more than 2.5 h. Adjustment of drug dosage prior to or during surgery may be required to optimize therapy, but before this can be achieved precisely, more information on drug disposition during the operative procedures is needed.

Aged↗
PubMed1992

Phosphodiesterase-inhibitors enoximone and piroximone in cardiac surgery: influence on platelet count and function.

OBJECTIVE: Some phosphodiesterase (PDE)-inhibitors are believed to alter platelet count and function due to changes in intracellular cAMP. Whether newly developed (specific) PDE-inhibitors negatively influence platelet function in cardiac surgery should be investigated in a randomized study. METHODS: Eighty patients undergoing aorto-coronary bypass grafting were divided into 4 groups and received either the new PDE-III-inhibitor piroximone (group 1), the PDE-III-inhibitor enoximone (group 2), epinephrine (group 3) or no inotropic support (control). PDE-III-inhibitors were given as a bolus followed by infusion until starting of cardiopulmonary bypass (CPB). In addition to platelet count and a thrombelastogram, platelet function was assessed by aggregometry (ADP, epinephrine, collagen). Measurements were done before, during and after CPB until the 1st postoperative day. RESULTS: Platelet count and postoperative blood loss did not differ between the groups within the entire investigation period. Maximum aggregation and maximum gradient of platelet aggregation to all stimuli were not changed by either PDE-inhibitor enoximone or piroximone. CPB resulted in a significant decrease of all aggregation variables which was without differences due to treatment. Platelet aggregation recovered in the post-bypass period and exceeded baseline values on the 1st postoperative day. CONCLUSION: It is concluded that enoximone and the new PDE-III-inhibitor piroximone do not affect platelet function and can be used before CPB without risking platelet-related bleeding in cardiosurgical patients in the perioperative period.

Adenosine Triphosphate↗
PubMed1992

The effects of preoperative aspirin therapy on platelet function in cardiac surgery.

Extracorporeal circulation is known to have profound effects upon platelets. Changes in platelet function were assessed in 20 patients undergoing elective coronary artery bypass grafting (CABG) who stopped taking aspirin (100 mg per day) 5-7 days before the operation compared with 20 patients undergoing aortic valve replacement (AVR) who had never taken anticoagulants or aspirin. Platelet aggregometry was carried out using the turbidimetric technique (inducing agents: adenosine diphosphate (ADP) 1.0 and 2.0 mumol/l; collagen 4 micrograms/ml; epinephrine 25 mumol/l), and maximum aggregation as well as the maximum gradient of aggregation were monitored before, during, and after cardiopulmonary bypass (CPB) until the 1st postoperative (p.o.) day. Until the 1st p.o. day blood loss was significantly higher in the CABG (890 +/- 160 ml) than in the AVR patients (420 +/- 120 ml). A total of 8 units of packed red cells (PRC) were given in the CABG group, whereas no homologous blood was necessary in the AVR patients (P < 0.05). The aggregation variables of the CABG patients were lower than in the AVR patients as early as after the induction of anesthesia (difference in maximum aggregation ranged from 13-29%). During CPB and immediately thereafter, all aggregation variables were significantly reduced in the CABG patients (reduction in maximum aggregation ranged from -32 to -49%) and were significantly different from the platelet aggregation in the AVR patients. Five hours after CPB and on the 1st p.o. day platelet aggregation in the CABG group almost returned to baseline values, however, without reaching the values of the AVR patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Endocrine stress response in cataract operations with local anesthesia].

This study was undertaken to investigate the endocrine stress response during cataract surgery in local anaesthesia (LA) with or without additional sedation with midazolam (Dormicum). 20 patients for cataract surgery in LA were randomly allocated to the midazolam-group (before injection of LA, sedation with single doses of 1 mg midazolam until the patient was sleeping, but awakeable), and to the control-group without sedation. Premedication and LA were standardized. The investigation was performed at 7 measuring points starting at the arrival in the preparation room up to 30 min after surgery. Adrenaline in plasma was significantly lower in the midazolam-group. Intraoperatively, adrenaline increased in the control-group and decreased in the midazolam-group. In time course, noradrenaline in plasma decreased in the midazolam-group, in contrast to the control-group. With respect to ADH, ACTH and cortisol, no significant differences were found in group levels or time course, and concentrations remained within normal range. In contrast to the control-group, mean arterial pressure decreased in the midazolam-group during the course of time. There were no differences in heart rate or arterial oxygen saturation between the two groups. Local anaesthesia and premedication were sufficient to prevent psychic and surgical stressors. The slight sympathoadrenergic response in the control-group was significantly reduced by small doses of midazolam. Thus, a careful supplementation of local anaesthesia with midazolam appears advantageous for patients with cardiovascular disorders.

Adrenocorticotropic Hormone↗
PubMed1992

Transcranial Doppler sonography: effects of halothane, enflurane and isoflurane on blood flow velocity in the middle cerebral artery.

Systolic, diastolic, and mean blood flow velocity in the middle cerebral artery (Vs,mca; Vd,mca; Vm,mca) and pulsatility (Vs-Vd)/Vm of the waveform obtained were recorded in 51 patients before, during and after general anaesthesia. Transcranial Doppler (TCD) sonographic variables were measured in the awake patient and after induction of anaesthesia with thiopentone 5-6 mg kg-1. After tracheal intubation, 17 patients received 0.8% halothane and 66% nitrous oxide in oxygen for 30 min (15 min normoventilation; 15 min hyperventilation). The inspired halothane concentration was then increased to 1.6% for 45 min (15 min normoventilation; 15 min hyperventilation; 15 min normoventilation with nitrous oxide replaced by oxygen). Enflurane (1.7% for 30 min and 3.4% for 45 min) was given to another 17 patients; 17 other patients received isoflurane (1.2% and 2.4%). Mean arterial pressure (MAP), nasopharyngeal temperature, end-tidal carbon dioxide concentration, inspired and end-tidal anaesthetic agent concentrations, haemoglobin concentration, PVC and TCD variables were measured at the end of each 15 min period. After recovery from anaesthesia, TCD variables were measured again. There were no intergroup differences in changes in MAP, nasopharyngeal temperature, haemoglobin concentration and PCV. Halothane, enflurane and isoflurane at low doses and normoventilation had little influence on TCD variables compared with awake values. In large concentrations with nitrous oxide in oxygen and normoventilation, there were differences between the volatile agents. Halothane increased blood flow velocities, but enflurane and isoflurane caused little change. Hyperventilation always decreased blood flow velocities and increased pulsatility.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

The role of enoximone in cardiac surgery.

After cardiopulmonary bypass (CPB), some patients may require circulatory support. This study examined the role of the phosphodiesterase-III inhibitor, enoximone, in cardiac surgery. Eighty patients selected by chance were allocated randomly to two groups: 40 patients received enoximone 1.0 mg kg-1 approximately 10 min before weaning from CPB and 40 served as a control group. Additional pharmacological therapy (adrenaline, noradrenaline, nitroglycerin) was given, when necessary, by anaesthetists who were not involved in the study. In addition to standard monitoring, skin capillary blood flow was assessed using a laser Doppler technique before, during and after CPB until 2 h after the end of the operation. In the period after bypass, cardiac index was always significantly greater in the enoximone than in the control group. Systemic and pulmonary vascular resistance were less in the enoximone-treated patients, indicating a reduction in right and left ventricular wall stress. Oxygen consumption in the enoximone patients was significantly greater after CPB, whereas intrapulmonary shunting was comparable in the two groups. In comparison with baseline values, skin capillary blood flow in the enoximone patients was always greater than that in the control group. In comparison with the control patients, significantly fewer enoximone patients needed adrenaline, and in a smaller dose, even 2 h after operation, whereas more enoximone patients required noradrenaline therapy for a short period. We conclude that the use of enoximone before weaning from CPB improved overall cardiac function, reduced the need of catecholaminergic inotropic support, and provided increased organ perfusion up to 2 h after operation.

Adult↗
PubMed1992

Endothelin plasma levels in old and young patients during open heart surgery: correlations to cardiopulmonary and endocrinology parameters.

We compared endothelin (ET) plasma levels during and after aortocoronary bypass (CPB) grafting in old and young patients. Correlations to cardiopulmonary parameters and catecholamines were tested. The study included 22 patients (11 aged greater than 70 years and 11 aged less than 55 years). Measurements were performed after induction of anesthesia (baseline), before bypass, during bypass, after patients were weaned off bypass, at the end of operation, and after 4-h intensive care (IC) treatment. ET [radioimmunoassay (RIA) technique] and catecholamines [high pressure liquid chromatography (HPLC) technique] plasma levels were determined from arterial blood samples; hemodynamics (pulmonary artery catheter), oxygen data, and laser Doppler flow were also monitored. Baseline ET plasma levels were within normal range (young, 3.1 +/- 0.9 pg/ml, old, 4.5 +/- 1.4 pg/ml). Old patients had higher values during the entire investigation period. During CPB ET plasma levels increased to a maximum immediately after patients were weaned off bypass. A significant increase (twofold to baseline) was noted during IC therapy. ET plasma levels did not correlate to catecholamine plasma levels or to hemodynamic or laser Doppler flow parameters. A significant correlation existed between ET plasma levels and oxygen consumption. Monitoring ET plasma levels appears to be of minor value in predicting circulatory changes and assessing surgical stress. Further investigations must elucidate the increase in oxygen consumption and its correlation to ET plasma level.

Aged↗
PubMed1992

Influence of five different priming solutions on platelet function in patients undergoing cardiac surgery.

The ideal choice of a priming solution of the cardiopulmonary bypass (CPB) and its influence on the hemostatic system are not clear. Addition of albumin was reported to inhibit platelet damaging by blood-surface interactions ("coating"). To explore this possibility in 60 consecutive male patients undergoing elective aortocoronary bypass grafting, five different priming solutions were randomly used: (1) 1000 mL of 5% dextrose + 1000 mL of Ringer's solution (RS) + 250 mL of 5% human albumin (HA); (2) 1850 mL of RS + 400 mL of 20% HA; (3) 1750 mL of RS + 500 mL of 10% low molecular weight hydroxyethyl starch (molecular weight average: 200,000; molar substitution ratio: 0.5); (4) 1750 mL of RS + 500 mL of 3.5% gelatin; (5) 2250 mL of RS. Platelet function was studied by aggregometry (= turbidometric technique; 1.0 and 2.0 mumol/L of adenosine diphosphate (ADP), 4 microL/mL of collagen, 25 mumol/L of epinephrine) before, during, and after CPB until the first postoperative day. Blood loss and need for homologous blood was not different between the groups. During CPB, maximum platelet aggregation induced by ADP was least compromised in group 1 and group 4. At the end of the operation ADP-induced aggregation increased in group 1 (+27%), whereas aggregation was decreased in the other priming solution groups. A significant increase in maximum aggregation was found in group 1 even on the first postoperative day (+132% +/- 16%). Collagen-induced aggregation was also least compromised in group 1. Epinephrine-induced platelet aggregation did not change and was similar for all groups. Maximum gradient of aggregation was influenced in an identical way as maximum aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1992

[Studies using S-(+)-ketamine on probands. Endocrine and circulatory reactions, recovery and dream experiences].

UNLABELLED: Clinically used ketamine is a racemic mixture of two isomers, S(+)- and R(-)-ketamine. The anaesthetic potency of S(+)-ketamine was found to be three times higher than that of R(-)-ketamine. It was the aim of this study to compare the effects of racemic ketamine and S(+)-ketamine on endocrine and cardiovascular parameters, recovery and psychomimetic reactions in young healthy volunteers. METHODS: 6 women and 4 men between 23 and 38 years were investigated twice in a randomized double blind cross-over design receiving injections of 2 mg/kg BW racemic ketamine or 1 mg/kg BW S(+)-ketamine at an interval of at least 7 days. Samples were taken from a central venous catheter before and 1, 3, 5, 10, 15, 30, 60 and 120 min after injection for analysis of adrenaline, noradrenaline (by high pressure liquid chromatography with electrochemical detection), ADH, ACTH, cortisol (by radio immuno assay), glucose, lactate and free glycerol. In addition, SAP, HR, and arterial oxygen saturation were measured, and return of consciousness and orientation were protocoled. Incidence and assessment of dreams were reported by the volunteers. RESULTS: Adrenaline, noradrenaline, ACTH, cortisol, lactate and free glycerol in plasma as well as SAP and HR increased significantly after injection of both racemic ketamine and S(+)-ketamine. The influence on ADH and glucose was not significant. There were no differences between racemic ketamine and S(+)-ketamine in these parameters. Recovery was significantly improved after administration of S(+)-ketamine. Simple orders were followed after 7.9 +/- 1.1 vs. 9.2 +/- 1.2 min (P = 0.004). Orientation with respect to the person returned after 9.0 +/- 1.8 vs. 11.5 +/- 2.5 min (P = 0.004); with respect to time and location after 10.1 +/- 2.1 min vs. 13.4 +/- 4.0 min (P = 0.007). 18 dreams were reported; assessment was positive in 13 cases and indifferent in 5 cases, none was negative. In 7 of 10 cases, the investigators were able to identify that S(+)-ketamine had been injected. CONCLUSION: With respect to endocrine and cardiovascular parameters, the pharmacodynamic effects of racemic and S(+)-ketamine were comparable. Because of the significant improvement in recovery and the reduced quantitative drug load, S(+)-ketamine offers a clear clinical advantage compared with currently used racemic ketamine.

Adrenocorticotropic Hormone↗
PubMed1992

[Cardiorespiratory and microcirculatory effects following volume replacement using a new hydroxyethyl starch preparation].

Volume therapy is often necessary in cardiac surgery to maintain stable haemodynamics. Various different hydroxyethyl starch (HAES) solutions with different concentrations, mean molecular weights, and degrees of substitution are available for this purpose. In determining the ideal type of volume therapy, not only changes in macrohaemodynamics, but also the influence on microcirculatory blood flow have to be taken into account. The efficacy of a new 10% HAES 130/0.5 solution was studied in cardiac surgery patients in comparison to a standard 10% HAES 200/0.5 preparation. METHODS. In patients scheduled for elective aortocoronary bypass grafting who had a pulmonary capillary wedge pressure (PCWP) of less than 4 mm Hg after induction of anaesthesia, either a new 10% HAES 130/0.5 (n = 15) or a standard 10% HAES 200/0.5 solution (n = 15) was infused to double the reduced PCWP; 15 patients without volume therapy served as controls (n = 15). A two-channel laser Doppler skin blood-flux monitor was used to evaluate microcirculatory alterations. Measurements of laser Doppler flux (LDF) was simultaneously performed at the patient's forehead and forearm before and after volume infusion as well as during and after cardiopulmonary bypass (CPB). In addition, changes in gross haemodynamics were documented using a pulmonary artery catheter. Plasma viscosity and various laboratory parameters, including calculation of intrapulmonary right-to-left shunting (Qs/Qt), were also measured. RESULTS. Cardiac index (CI) increased in both volume groups (HAES 130: max. +38%; HAES 200: +55%). The increases in PCWP and CI were maintained at 40 min after volume infusion only in the HAES 200 patients. Systemic vascular resistance (SVR) decreased most markedly after infusion of HAES 200 (-34%; HAES 130: -18%). No further differences in gross haemodynamics could be seen after CPB. Plasma viscosity and colloid osmotic pressure increased in both HAES groups without significant differences. During the entire investigation period, pulmonary gas exchange (paO2) and Qs/Qt did not differ between the groups. Infusion of both HAES solutions resulted in an increase in LDF that was most pronounced after infusion of HAES 200 (forehead LDF: +81%; HAES 130: +18%) and was evident in the post-bypass period only in these patients (LDF: HAES 200: +82%; HAES 130: -20%; control: -43%). No correlation between LDF values and the other haemodynamic and laboratory parameters could be demonstrated. CONCLUSION. The improvement in macrohaemodynamics was of shorter duration after infusion of the new HAES 130 solution than after standard HAES 200. Volume replacement with HAES 200 resulted in an increase in microcirculatory blood flow that was more pronounced and of longer duration than in the HAES 130 patients. Thus, HAES 130 seems to be less effective than HAES 200 for volume replacement; HAES 200 should be preferred in patients undergoing cardiac surgery.

Cardiac Surgical Procedures↗
PubMed1992

[Studies using S-(+)-ketamine on probands. Computerized EEG-analysis and transcranial Doppler ultrasonography].

It has been shown in the recent literature that the anaesthetic potency of the ketamine isomer S(+)-ketamine is twice that of the racemic mixture used in clinical practice. METHODS. With approval of the local ethics committee, we investigated the effects of a bolus injection of 2 mg/kg racemic ketamine or 1 mg/kg S(+)-ketamine, respectively, on the electroencephalogram (EEG) and transcranial Doppler sonography (TCD) of the middle cerebral artery in ten healthy volunteers by means of a randomised, double-blind, cross-over design. Spectral edge frequency, total activity and activity of the alpha, beta, delta, and theta bands were assessed by bihemispheric leads using the Neurotrac system before (MZP 1) and 1, 3, 5, 10, 15, 30, 60, and 120 min after injection (MZP 2-9). Simultaneously, systolic (Vs-MCA), diastolic (Vd-MCA), and mean (Vm-MCA) blood flow velocities in the middle cerebral artery and pulsatility (Vs-Vd)/Vm were recorded. Statistics consisted of two-dimensional analysis of variance with P < 0.05 considered as significant. RESULTS. Racemic ketamine and S(+)-ketamine produced comparable effects on the EEG. Theta- and beta-activities increased between the 1st and 10th min after injection and returned to near baseline values thereafter. 120 min after injection, the absolute delta- and theta-activities were higher following racemic ketamine when compared to the S(+)-ketamine group. However, significant differences between the groups could not be confirmed statistically. TCD variables changed considerably in the course of the study without intergroup differences. Compared to the baseline values, Vs-MCA, Vd-MCA, and Vm-MCA increased significantly for the first 15 min after injection with a maximum at MZP 3. The pulsatility of the obtained Doppler waveform (Vs-Vd)/Vm showed significant decreases at MZP 2-4. CONCLUSIONS. In our study, both racemic ketamine and its isomer S(+)-ketamine produced similar EEG changes consistent with the data from earlier studies. However, the relative lower proportion of slow EEG activity at the end of the study might indicate a better recovery of cortical function following S(+)-ketamine than after racemic ketamine. Assuming a close relationship between cerebral blood flow velocity and cerebral blood flow, our TCD results suggest that both racemic ketamine and S(+)-ketamine will considerably increase cerebral blood flow in spontaneously breathing volunteers. Such an effect has been observed by others and, at least partly, can be explained by a concomitant increase in arterial carbon dioxide partial pressure.

Adult↗