Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 235 records · Page 13Linked to original sources

PubMed1995

[Increase in interleukin-6 plasma concentrations following hypotensive anesthesia with sodium nitroprusside].

In animal models authors have dealt with the question of whether hypotension alone can cause an acute-phase response even in the absence of marked blood loss and trauma. Sodium nitroprusside (SNP), which was employed in the animal models, is also used to induce hypotension in humans. Since no data are available on human subjects plasma concentrations of interleukin-6 (IL-6), an important mediator of the acute-phase response, were studied in patients during SNP infusion for induction of hypotension. METHODS. After approval by the local ethics committee, 20 patients scheduled for elective oto-rhino-laryngological operations participated in this randomised prospective study. Anaesthesia was induced with fentanyl, etomidate, vecuronium and succinylcholine and was maintained with isoflurane in 66% N2O and 33% O2. Ten patients received SNP to reduce mean arterial blood pressure to 50 mmHg, while another ten patients served as controls. Blood samples were taken before the induction of anaesthesia, during surgery (at the end of the SNP infusion), 60 min after surgery and on the day after surgery. IL-6 concentrations were determined by means of enzyme-linked immunosorbent assay. Epinephrine and norepinephrine in plasma were measured by high-pressure liquid chromatography with electrochemical detection. RESULTS. The IL-6 plasma concentration increased significantly from 3.2 (0-7.5) pg/ml (median and range) to 31.8 (9-42.2) pg/ml in the SNP group and from 3.5 (0-8.3) pg/ml to 15.2 (7.4-19) pg/ml in the control group on the morning after surgery. The IL-6 values at this time were significantly (P < 0.05) higher in the SNP group than in the controls. Norepinephrine increased significantly from 263 (150-920) pg/ml (median and range) preoperatively to 419 (115-897) pg/ml, and the epinephrine concentrations rose significantly from 77 (12-159) pg/ml to 115 (83-330) pg/ml at the end of SNP administration. No significant changes in the catecholamine concentrations were observed in the control group. CONCLUSIONS. The SNP infusion exerted an important additional stimulus for IL-6 release after relatively mild surgical trauma in both groups. This finding is probably due to the liberation of NO from the SNP molecule and an increase in the intracellular concentration of cGMP. The elevation of the plasma catecholamines immediately after SNP administration should also be taken into account, because an augmentation of the cAMP in various cell types has been proven to result in increased release of IL-6.

Adult↗

PubMed1995

[Continuous monitoring of critical patients with a newly developed pulmonary arterial catheter. A cost analysis].

The introduction of flow-directed pulmonary artery (PA) catheters has helped to improve our knowledge of cardiovascular physiology. There have been several developments of this equipment in recent years, including continuous monitoring of mixed-venous O2 saturation (SvO2) and cardiac output (CO). The high purchase price, however, is an obstacle to its use in the critically ill. The aim of the present study was to analyse the actual costs of these devices in comparison to standardly used intermittent monitoring of SvO2 and CO. METHODS. Thirty critically ill patients in a surgical intensive care unit (ICU) were prospectively studied. PA catheter monitoring was indicated by physicians who were not involved in the study. The patients were randomly allocated to one of the following groups: 1. a standard PA catheter was used, and SvO2 and CO were intermittently measured 6 times a day on a routine basis and additionally when necessary from the clinical point of view; 2. SvO2 was continuously measured using a fiberoptic PA catheter; and 3. CO was continuously monitored using a newly developed PA catheter. Costs for the catheter equipment and laboratory analyses (SvO2) were calculated and the durations of intermittent monitoring techniques were measured. Costs for the 'hardware' (monitor, blood gas analyser) were not taken into account. SvO2 was measured by the ICU staff using an ICU-owned blood gas analyser (4.78 DM/analysis) and by a central laboratory unit, which had to be paid for its analyses (30.50 DM/analysis), respectively. RESULTS. The groups were comparable with regard to their demographic data. A total of 378 intermittent measurements of SvO2 and 449 mean CO measurements (1611 single bolus CO measurements) were carried out in the patients in whom a standard PA catheter was inserted. For daily calibration, a total of 50 single SvO2 measurements were done in the group in which SvO2 was continuously monitored. A total of 27.7 h were spent for intermittent SvO2 measurements (time range of one analysis using the ICU-based blood gas analyser: 4.0 to 7.9 min); intermittent CO monitoring took a total of 14.2 h (time range of one mean CO measurement: 1.6 to 3.0 min). When blood gases were analysed by a central laboratory unit, costs for intermittent SvO2 were tremendously higher than when monitored continuously. CONCLUSION. Monitoring devices that provide us with continuous information on the patient's state may have advantages in the management of the critically ill. Whether the patient's 'outcome' can be improved by monitoring SvO2 and CO continuously was not addressed by the present study. Instead, this study focused on the question of whether these devices are more cost-intensive than standard PA catheter monitoring systems. Costs for laboratory analyses can blunt the advantage of lower costs for the standard PA catheter. Intermittent (standard) monitoring of SvO2 and CO was significantly more time-consuming than the continuous methods. It can be summarised that although purchase costs for the more advanced PA catheters are higher than for standard PA catheters, the use of these continuous monitoring devices in the critically ill can be justified from a financial point of view.

Cardiac Output↗

PubMed1995

[Mechanical autologous transfusion in orthopedic surgery in children. Is the use of mechanical autologous transfusion possible even in pediatric orthopedic surgical procedures?].

The use of autotransfusion devices is an established method of reducing the need for homologous transfusions in surgery [3, 11, 13], but technical factors still contraindicate the washing and concentration of blood volumes smaller than 300 ml. Therefore, haemoconcentration of small volumes of salvaged blood, as usually found in paediatric surgery, is considered to be a complicated and questionable practice [5]. Whereas these amounts of blood loss are easily tolerated by adults, they may necessitate homologous transfusions in paediatric surgery. In a prospective study, we investigated whether a simple technical modification in the processing of salvaged blood could facilitate the use of autotransfusion devices, especially in children. PATIENTS AND METHODS. Intraoperative blood salvage was performed in children 6 months to 10 years old undergoing surgery for hip dysplasia. Autotransfusion (Dideco STAT) was started when the blood loss was estimated to be more than 20% of the total blood volume (TBV). As a reference, we used a formula based on body weight [10]: for children up to the age of 6 years 80 ml/kg blood volume and for children up to 10 years 75 ml/kg. The total volume of salvaged fluid including blood, anticoagulant solution, and surgical irrigation was collected in a reservoir and transferred to the autotransfusion set, after which the reservoir was rinsed with 500 ml 0.9% saline solution in order to save the remaining blood. After processing, the blood was stored in the retransfusion bag. By adding the same volume of plasma expander (6% hydroxyethyl starch [HES], molecular weight 450,000), spontaneous sedimentation of the washed autologous erythrocytes (RBCs) for 10-15 min led to a concentrate of RBCs. After 10 mu filtration, the RBC suspension was retransfused (Figs. 1-3). RESULTS. Within 12 months, autotransfusion was performed during 6 out of 15 surgical procedures according to the method described above. The calculated blood loss averaged 25.6% of TBV, of which 21.4% (= 272 ml) could be processed by the autotransfusion device (Table 3). The mean values of 2.6 g/dl haemoglobin (Hb) and 6.8% haematocrit (HCt) in the salvaged blood increased to 9.4 g/dl and 27.3% in the processed RBC concentrates. After adding 6% HES solution, spontaneous sedimentation of the RBCs led to values of Hb 22.1 g/dl and HCt 59.8%. An average of 59.5 ml (22-99 ml) sedimented RBCs was retransfused to the patients, including 11.6 ml 6% HES solution (Table 4). In this manner, the need for homologous transfusions could be avoided in these patients both during and after surgery. CONCLUSIONS. This study shows that the use of blood salvaging in paediatric surgery is indicated under certain conditions. With the aid of the simple modification described above, we solved the main problem in paediatric autotransfusion by concentrating RBC suspensions with low Hb and Hct values after using the autotransfusion device.

Blood Sedimentation↗

PubMed1995

[Tamm-Horsfall protein, alpha-1- and beta-2-microglobulin as kidney function markers in heart surgery].

After cardiac surgery, transient renal dysfunction often occurs. Regional differentiation of these processes is possible only using invasive techniques, including renal biopsy. Approximately 30 different plasma protein components have been identified in the urine of healthy individuals by means of qualitative and quantitative immunochemical methods. The detection of microalbuminuria has high diagnostic relevance for the early diagnosis of renal damage at a reversible stage. One typical urinary protein is Tamm-Horsfall protein (THp). After histochemical staining of human kidney sections, activity is seen in the loop of Henle and initial distal tubule. The assay of alpha-1 microglobulin (MG) in urine is considered one of the most efficient laboratory parameters for the diagnosis of tubular lesions. Serum concentrations of alpha-1 MG are less dependent on extrarenal changes than are those of other low-molecular-weight proteins. beta-2 MG is also one of the standards used in recent years for diagnostic relevance. Urinary albumin excretion, normally less than 30 mg per day, sometimes increases after glomerular damage. Some renal function tests are used daily in many intensive care units, e.g. creatinine clearance (CCr) or urea and sodium excretion. Renal dysfunction should, however, be further examined to localise regional damage and to seek new clinical standards in addition to the conventional tests. METHODS. After obtaining the agreement of the local ethics committee, 30 patients were divided into two groups of 15 each: group I without renal dysfunction and CCr more than 60 ml/min; and group II with CCr below 60 ml/min. THp and alpha-1 MG were measured pre- and postoperatively after open heart surgery with the ELISA and beta-2 MG with the nephelometric technique. These parameters were compared with clinical standards such as albumin excretion, blood urea nitrogen (BUN), urea clearance, and fractional sodium excretion. RESULTS. The CCr did not change in group I from the pre- to postoperative period (81.5 to 85.1 and 91.4 ml/min), nor did excretion of THp (20.1 to 25.0 and 24.8 mg/day), correlation r = 0.7; P < 0.001). The elimination of alpha-1 and beta-2 MG was significantly higher in the postoperative period in this group (alpha-1: 7.2 to 44.1 and 100.6 mg/day; beta-2: 0.3 to 2.1 and 3.2 mg/day). In group II CCr showed pathological values (36.8 to 31.1 and 36.3 ml/min), as did simultaneous THp (13.5 to 9.7 and 12.7 mg/day). alpha-1 and beta-2 MG values became more pathological in the postoperative period than in group I (alpha-1: 32.8 to 113.9 and 198.5 mg/day; beta-2: 0.7 to 5.8 and 16.9 mg/day). DISCUSSION. Measurement of the excretion of THp and alpha-1 and beta-2 MG is a useful addition to present clinical standards for recognising early changes in renal function. The increases in the postoperative period after cardiac surgery showed tubular damage even in patients without predictive risk factors or clinical signs. In patients with renal dysfunction open heart surgery and extracorporeal circulation led to significant tubular damage.

Aged↗

PubMed1995

[Does controlled hypotension with nitroprusside affect platelet function?].

Induced hypotension is an accepted technique to reduce intraoperative blood loss and thereby ensures satisfactory operating conditions, especially in microscopic interventions. Sodium nitroprusside (NP), which is often used for induced hypotension, was reported to inhibit platelet aggregation in vitro. Impairment of platelet function implies a higher bleeding risk, which would make the use of NP for induced hypotension questionable. METHODS. With the approval of the local ethics committee, 30 patients scheduled for nasal septum operations were included in this randomised study. For induction of anaesthesia 2 mg vecuronium, 0.1 mg fentanyl, 0.2 mg/kg etomidate, and 1 mg/kg succinylcholine were used. After tracheal intubation the patients inhaled 1.0-1.5 vol.% isoflurane in a gas mixture containing 66% nitrous oxide in oxygen. Fifteen patients received an i.v. infusion of NP for 60 min. The concentrations chosen produced a decrease of mean arterial blood pressure to 50 mm Hg. Blood samples were taken before induction of anaesthesia; after induction of anaesthesia but before beginning of the operation; and 60 min after the beginning of the operation. This time-point coincided with the end of NP administration in the study group. The last blood sample was drawn the morning after the operation. Platelet function was determined in platelet-rich plasma by a turbidometric method after adding 22 mumol/l epinephrine to induce aggregation. The spontaneous aggregation was measured in whole blood using impedance aggregometry. Data within one group were analysed using analysis of variance. Student's t-test for unpaired values served to compare data between the two groups. RESULTS. Biometric data in the two groups were comparable. The blood loss in the control group [265 (190-410) ml] significantly exceeded (P < 0.05) that in the hypotensive group [125 (75-210) ml]. No significant changes in platelet function were found throughout the study period in the patients treated with NP. In the control patients the epinephrine-induced aggregation increased significantly from 53.1 +/- 5.3% before anaesthesia to 72.1 +/- 3.3% the morning after the intervention. The spontaneous aggregation showed a significant increase from 0.718 +/- 0.338 Ohm/h before anaesthesia to 2.164 +/- 0.442 Ohm/h 60 min after the beginning of the operation. The value on the 1st postoperative day (2.266 +/- 0.448 Ohm/h) was also significantly higher than the basal value. CONCLUSIONS. In contradiction to in vitro studies using high concentrations of NP, we could not find a decrease in platelet aggregation due to hypotensive anaesthesia with this drug in vivo. In the control group a significant increase in platelet aggregation was observed, which was probably counteracted in the hypotensive patients by the interaction of NP with cyclic guanosine monophosphate (c-GMP). NP augments the intracellular concentration of c-GMP, which is known to decrease platelet aggregation.

Adolescent↗

PubMed1995

Circulating adhesion molecules in cardiac operations: influence of high-dose aprotinin.

Cardiac operations using cardiopulmonary bypass (CPB) are associated with a systemic inflammatory response most likely attributable to the release of various inflammatory mediators and activation of complement or coagulation cascade. In addition, (circulating) adhesion molecules, such as endothelial leukocyte adhesion molecule (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1), appear to be of central importance in the CPB-related inflammatory process. In this situation, antiproteases, such as aprotinin, may help to prevent damage of endothelial integrity. In a prospective study, 40 consecutive patients undergoing elective cardiac operation were randomly divided into two groups (with 20 patients in each group): in group 1 "high-dose" aprotinin was used (2 million IU of aprotinin before CPB, 500,000 IU/h until end of operation, 2 million IU added to the prime) (with aprotinin), and in group 2 no aprotinin was given (without aprotinin). Circulating adhesion molecules (cICAM-1, cELAM-1, and cVCAM-1) were measured from arterial blood samples using ELISA after induction of anesthesia (baseline), during CPB, at the end of the operation, 5 hours after CPB, and on the first postoperative day. The two groups were comparable concerning their biometric profile and CPB data. Baseline values of circulating adhesion molecules were within normal range and similar in both groups. During CPB, hemodilution resulted in a decrease in all circulating adhesion molecules. On the first postoperative day, cICAM-1 (with aprotinin, 215 +/- 32 ng/mL; without aprotinin, 230 +/- 40 ng/mL) and cELAM-1 (with aprotinin, 28 +/- 6 ng/mL; without aprotinin, 31 +/- 6 ng/mL) returned to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

RETRACTED: Cardiorespiratory response of intravenous angiotensin-converting enzyme inhibitor enalaprilat in hypertensive cardiac surgery patients.

Twenty-four patients undergoing elective coronary artery bypass surgery were studied. Either the angiotensin-converting enzyme (ACE) inhibitor enalaprilat, 0.06 mg/kg, (n = 12), or saline solution (= control group; n = 12), was randomly and blindly administered intravenously when the mean arterial blood pressure (MAP) increased to 90 mmHg after induction of anesthesia. Cardiorespiratory parameters were studied before injection, during the subsequent 30 minutes, precardiopulmonary bypass (CPB), post-CPB, and at the end of surgery. MAP was significantly reduced 5 minutes after administration of enalaprilat. The peak reduction of blood pressure was observed after 30 minutes (from 98 +/- 4 to 68 +/- 8 mmHg). Even immediately before CPB (112 +/- 12 minutes after injection of enalaprilat), MAP and systemic vascular resistance were significantly lower than baseline values. Heart rate remained almost unchanged in both groups. Cardiac index increased slightly in the enalaprilat patients (maximum: +0.75 L/min/m2 20 minutes after injection). Filling pressures (central venous pressure, pulmonary capillary wedge pressure) were also significantly reduced by enalaprilat. There were no differences from the control patients with regard to changes in right ventricular hemodynamics (right ventricular ejection fraction, right ventricular end-diastolic volume, right ventricular end-systolic volume), pulmonary gas exchange (PaO2), or intrapulmonary right-to-left shunting (Qs/Qt). VO2 increased only in the enalaprilat patients (from 179 +/- 28 to 230 +/- 30 mL/min) (p < 0.05). Cardiorespiratory parameters did not differ between the two groups post-CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗

PubMed1995

[Effects of lumbar peridural anesthesia on tissue pO2 of the large intestine in man].

AIM: The aim of this study was to investigate the effect of 15 ml bupivacaine 0.25%, given via an epidural catheter, on the tissue-PO2 of the colon wall in humans. METHODS: Nine patients were studied during elective colorectal surgery. The tissue-PO2 was measured by polarography, using a multiwire surface probe. RESULTS: There was no significant change in cardiac index and arterial oxygen delivery after the injection of bupivacaine. At the serosal side of the colon wall the tissue-PO2 increased from 34 to 51 mmHg after epidural bupivacaine, which is statistically significant. Spinal nerve block produces sympathetic denervation of the bowel with an increase of regional nutritive blood flow. CONCLUSION: It is concluded that epidural bupivacaine has a favourable effect on tissue oxygenation of the colon during colorectal surgery.

Aged↗

PubMed1995

Local anesthetics potently block a potential insensitive potassium channel in myelinated nerve.

Effects of some local anesthetics were studied in patch clamp experiments on enzymatically demyelinated peripheral amphibian nerve fibers. Micromolar concentrations of external bupivacaine depolarized the excised membrane considerably. The flicker K+ channel was found to be the most sensitive ion channel to local anesthetics in this preparation. Half-maximum inhibiting concentrations (IC50) for extracellular application of bupivacaine, ropivacaine, etidocaine, mepivacaine, lidocaine, and QX-314 were 0.21, 4.2, 8.6, 56, 220, and > 10,000 microM, respectively. The corresponding concentration-effect curves could be fitted under the assumption of a 1:1 reaction. Application from the axoplasmic side resulted in clearly lower potencies with IC50 values of 2.1, 6.6, 16, 300, 1,200, and 1,250 microM, respectively. The log(IC50)-values of the local anesthetics linearly depended on the logarithm of their octanol:buffer distribution coefficients with two regression lines for the piperidine derivatives and the standard amino-amides indicating an inherently higher potency of the cyclic piperidine series. Amide-linked local anesthetics did not impair the amplitude of the single-channel current but prolonged the time of the channel to be in the closed state derived as time constants tau c from closed-time histograms. With etidocaine and lidocaine tau c was 133 and 7.2 ms, and proved to be independent of concentration. With the most potent bupivacaine time constants of wash in and wash out were 1.8 and 5.2 s for 600 nM bupivacaine. After lowering the extracellular pH from 7.4 to 6.6, externally applied bupivacaine showed a reduced potency, whereas at higher pH of 8.2 the block was slightly enhanced. Intracellular pH of 6.4, 7.2, 8.0 had almost no effect on internal bupivacaine block. It is concluded that local anesthetics block the flicker K+ channel by impeding its gating but not its conductance. The slow blocker bupivacaine and the fast blocker lidocaine compete for the same receptor. Lipophilic interactions are of importance for blockade but besides a hydrophobic pathway, there exists also a hydrophilic pathway to the binding site which could only be reached from the cytoplasmic side of the membrane. Under physiological conditions, blockade of the flicker K+ channel which is more sensitive to bupivacaine than the Na+ channel might lead via membrane depolarization and the resulting sodium channel inactivation to a pronounced block of conduction in thin fibers.

Anesthetics, Local↗

PubMed1995

Endothelial-related coagulation in cardiac surgery.

The endothelium appears to play an important role in the regulation of intravascular coagulation. Thrombomodulin is one of the anticoagulant substances that is expressed by endothelial cells. The influence of age and illness on the thrombomodulin-protein C system was studied prospectively in 80 cardiac surgery patients. Patients > 70 yr old (n = 20) were compared with patients < 50 yr (n = 20) (group I), and patients undergoing a simple cardiac procedure (n = 20) were compared with patients scheduled for complex surgery (n = 20) (group II). Thrombomodulin (normal < 40 ng ml-1), protein C and (free) protein S plasma concentrations were measured by enzyme-linked immunosorbent assays (ELISA) after induction of anaesthesia (baseline values), during and after cardiopulmonary bypass (CPB), at the end of surgery, 5 h after CPB and on the first day after operation. Blood loss and use of homologous blood and blood products were significantly greater in patients > 70 yr and in those undergoing complex surgery. At baseline, thrombomodulin concentration was increased in patients undergoing complex surgery (mean 52 (sd 9) ng ml-1). After bypass and after operation, thrombomodulin increased most in patients > 70 yr (from 40 (8) to 78 (10) ng ml-1) and in those patients who underwent complex cardiac operations (from 52 (8) to 79 (10 ng ml-1) (P < 0.05). Changes in protein C and protein S concentrations were similar in all groups. On the first day after operation only, protein C concentrations were reduced in patients > 70 yr and in patients who underwent complex cardiac surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Inhibition of phagocytosis and killing of bacteria by anaesthetic agents in vitro.

Polymorphonuclear leucocytes (PMNL) are an essential contribution to protection from bacterial infection. We have examined the effects of thiopentone, etomidate, ketamine and flunitrazepam on phagocytosis and killing of Staphylococcus aureus and Escherichia coli by PMNL in vitro with fluorescence microscopy. All anaesthetic agents significantly inhibited both phagocytosis and bactericidal activity. The additives in the commercial preparations may have contributed to the suppression.

Adult↗

PubMed1995

Does the type of volume therapy influence endothelial-related coagulation in the critically ill?

The endothelium plays an important role in the regulation of haemostasis by producing substances such as thrombomodulin (TM). The influence of long-term volume replacement with different types of fluid on the TM-protein C-protein S system was investigated in a prospective, randomized study. Thirty trauma patients and 30 patients suffering from sepsis after major surgery received either 10% low-molecular weight (LMW) hydroxyethylstarch solution (HES-trauma, n = 15; HES-sepsis, n = 15) or 20% human albumin (HA-trauma, n = 15; HA-sepsis, n = 15) for 5 days to maintain central venous pressure (CVP) between 12 and 16 mm Hg. Plasma concentrations of TM, protein C, (free) protein S and thrombin-antithrombin (TAT) were measured in arterial blood samples obtained on the day of admission to the intensive care unit or on the day of diagnosis of sepsis and over the next 5 days. There were no differences between HA- and HES-treated trauma patients. Protein C and protein S also did not differ between HA- and HES-treatments. At baseline, TM plasma concentrations were increased to > 40 micrograms litre-1 in both sepsis groups only. In the HA-sepsis group, TM increased significantly (from 48.1 (SD 13.9) to 68.4 (13.0) micrograms litre-1), whereas it remained almost unchanged in the HES-sepsis group. In HES-sepsis patients, protein C (from 51.0 (10.1) to 71.9 (8.9)%) and protein S (from 19.0 (6.0) to 40.8 (11.4)%) increased significantly during the study, whereas both remained reduced in HA-patients. TAT (indicating intravascular coagulation) did not differ between the two fluid groups. We conclude that in trauma patients, the type of volume therapy had no influence on the TM-protein C-protein S system. In sepsis patients, volume therapy with HES was beneficial, whereas infusion of HA had no substantial positive effect on endothelial-associated coagulation.

Adult↗

PubMed1995

Influence of intravenous administration of angiotensin-converting enzyme inhibitor enalaprilat on cardiovascular mediators in cardiac surgery patients.

The renin-angiotensin system (RAS) is important in controlling and maintaining cardiovascular homeostasis. In a randomized, prospective study, the response to intravenous (i.v.) administration of the angiotensin-converting enzyme (ACE) inhibitor enalaprilat (0.06 mg/kg) on important controllers of the circulation was investigated in 14 patients undergoing aortocoronary bypass grafting with a mean arterial blood pressure (MAP) > 85 mm Hg after induction of anesthesia. Fourteen patients received saline solution as placebo (control group). Endothelin (ET), atrial natriuretic peptide (ANP), catecholamine (epinephrine, norepinephrine) plasma levels, and ACE activity were measured from arterial blood sampled before injection of enalaprilat or NaCl solution (baseline values), 10 min and 30 min thereafter, immediately before the start of cardiopulmonary bypass (CPB), immediately after CPB, and at the end of surgery. MAP, heart rate (HR), cardiac index (CI), and systemic vascular resistance (SVR) were also monitored. ACE activity was similar at baseline in both groups; after i.v. injection of enalaprilat, it significantly decreased (from 35.1 +/- 11 to 4.4 +/- 1.0 U.min-1.L-1 30 min after injection) and remained reduced until the end of the operation (295 +/- 31 min after injection). ANP plasma levels were increased beyond normal (> 100 pg/mL) at baseline in both groups. They increased significantly in the control patients, but remained almost unchanged in the enalaprilat-treated patients within the entire study period. Plasma concentration of ET also increased only in the control group and was increased after CPB (8.6 +/- 1.2 pg/mL at the end of the operation).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

The effects of epidural and intravenous lidocaine on somatosensory evoked potentials after stimulation of the posterior tibial nerve.

The measurement of somatosensory evoked potentials (SEPs) after stimulation of the posterior tibial nerve (PTN-SEPs) has been proposed as an objective indicator of the quality of lumbar epidural block. It is unclear whether peak latency increases after epidural application of local anesthetics may be due in part to systemic effects of the drug absorbed from the epidural space. In this clinical study, we compared PTN-SEPs after intravenous and epidural administration of lidocaine to those of a control group who did not receive lidocaine. Plasma concentrations of lidocaine remained within expected ranges for epidural and intravenous administration. No subjects developed signs for overdose or toxicity. After epidural application of 2% lidocaine, mean latencies of peaks P1, N1, and P2 increased significantly in comparison to baseline values. In 3 of 10 patients, latency changes were not observed. Intravenous lidocaine did not produce statistically significant changes in latencies, although a trend toward increasing latencies appeared to be present. In the control group without lidocaine, no statistically significant changes occurred during the 1-h study period. No correlation was found between peak latency changes and plasma concentrations of lidocaine. We conclude that latency increases observed after epidural application of lidocaine are due primarily to local, not systemic, effects of the local anesthetic.

Absorption↗

PubMed1995

Circulating adhesion molecules in pediatric cardiac surgery.

Cardiopulmonary bypass (CPB) may be associated with the risk of a "whole body inflammation." Adhesion molecules, such as endothelial leukocyte adhesion molecule (ELAM-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1), seem to play a pivotal role in the inflammatory response. Soluble forms of these adhesion molecules may serve as markers of endothelial activation or damage. To elucidate whether plasma levels of soluble adhesion molecules differ between pediatric and adult cardiac surgery patients, 15 consecutive children younger than 5 yr undergoing CPB were prospectively studied and compared with adults scheduled for elective coronary artery bypass grafting and valve replacement. Plasma levels of circulating (soluble) adhesion molecules (sELAM-1, sICAM-1, sVCAM-1) were measured from arterial blood samples using enzyme-linked immunosorbent assays after induction of anesthesia (= "baseline"), during CPB, at the end of surgery, and on postoperative days 1 and 2. At baseline, plasma levels of all three soluble adhesion molecules were significantly higher in children than in adults. sELAM-1 and sICAM-1 plasma concentrations were even beyond normal in the children (sELAM-1: 88.8 +/- 13.8 ng/mL; sICAM-1: 349 +/- 27 ng/mL). During CPB and until the end of surgery, plasma levels of all adhesion molecules decreased in the children and remained almost unchanged in the adults. In the children, sELAM-1 remained lower than baseline values until the second postoperative day (45.2 +/- 12.2 ng/mL), whereas sICAM-1 increased in the postbypass period without, however, reaching baseline values (254 +/- 40 ng/mL).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Beta 2-adrenoceptor density of human lymphocytes after nitroprusside-induced hypotension.

The present study was undertaken to assess the influence of nitroprusside-induced hypotension on beta 2-adrenoceptor density. Twenty-four patients undergoing nose-septum corrections under general anesthesia were allocated randomly to a nitroprusside or control group. beta 2-Receptor density on lymphocytes was measured by binding studies using (-)125-iodocyanopindolol. Lymphocyte subpopulations B, T, Thelper, Tsuppressor, and natural killer cells were determined simultaneously by flow cytometry. Five of 12 nitroprusside-treated patients developed significant intraoperative increases of epinephrine levels (+69% versus preoperatively) which were not seen in the remaining seven patients. In these five patients, beta 2-receptor density of unfractionated lymphocytes was 26% lower (P < 0.05) on the first day after surgery compared with preoperative values. Since no changes in proportions of lymphocyte subpopulations were observed, these results are not caused by redistribution phenomena inducing a decrease of subsets with a high number of beta receptors. These findings suggest that beta 2-adrenergic responsiveness might be diminished after nitroprusside treatment in some patients.

Adrenergic beta-Antagonists↗

PubMed1995

Cerebrovascular carbon dioxide reactivity in carotid artery disease. Relation to intraoperative cerebral monitoring results in 100 carotid endarterectomies.

BACKGROUND: In patients with carotid artery disease, poor intracerebral collateralization is reflected by impaired cerebrovascular reactivity to carbon dioxide inhalation, which will improve after endarterectomy. The relationship between preoperative reactivity to carbon dioxide using transcranial Doppler sonography (TCD) and intraoperative changes of somatosensory evoked potentials (SEP) and TCD parameters were investigated. METHODS: In 94 patients, preoperative carbon dioxide reactivity was examined and defined impaired if mean blood flow velocity in the middle cerebral artery (Vm-MCA) increased less than 1.5% mmHg during carbon dioxide challenge. Patients then underwent 100 carotid operations under general anesthesia with both SEP and TCD monitoring. Shunts were placed if SEP amplitude decreased to less then 50% of control or central conduction time increased by 20% after clamping (critical SEP changes). TCD changes were defined as critical in case of a postclamping/preclamping Vm-MCA ratio < or = 0.4. The incidence of critical SEP and TCD changes was compared to preoperative carbon dioxide testing using Fisher's exact test with P < 0.05 considered significant. Postoperatively, neurologic state and carbon dioxide responsiveness were re-examined. RESULTS: Twelve patients showed impaired preoperative carbon dioxide reactivity on the side of operation, which improved markedly after surgery. The incidence of critical SEP changes in these cases (8.3%) was not significantly different from that in the remaining patients (14.8%). Critical SEP changes were significantly correlated with critical TCD changes (P < 0.0001). CONCLUSIONS: Patients with poor carbon dioxide reactivity (preoperative TCD testing) did not have an increased risk of cerebral ischemia during carotid surgery, as assessed by intraoperative SEP recording.

Blood Flow Velocity↗

PubMed1995

Continuous i.v. administration of the angiotensin-converting enzyme inhibitor enalaprilat in the critically ill: effects on regulators of circulatory homeostasis.

Several components are responsible for circulatory control at the central, regional, and microcirculatory level. Angiotensin-converting enzyme (ACE) inhibitors are known to act beneficially on circulation by various mechanisms. The influence of continuous i.v. administration of the ACE inhibitor enalaprilat on regulators of circulation was studied in 45 critically ill patients. According to a prospective randomized sequence, either 0.25 mg/h (group 1, n = 15) or 0.5 mg/h (group 2, n = 15) of enalaprilat or saline solution as placebo (control group, n = 15) were continuously given. Infusion was started on the day of admission to the intensive care unit (ICU) and continued for the next 5 days. From arterial blood samples, plasma levels of endothelin-1 (ET), atrial natriuretic peptide (ANP), renin, vasopressin, angiotensin-II, and catecholamines (epinephrine, norepinephrine) were measured. All measurements were carried out before infusion (= baseline values) and during the next 5 days. In both enalaprilat groups, mean arterial blood pressure (MAP) decreased similarly; heart rate (HR) and central venous pressure (CVP) did not change, and were without differences in comparison to the untreated control. Except for ET, plasma levels of all vasoactive substances exceeded normal range at baseline. Angiotensin-II plasma concentrations significantly decreased during enalaprilat infusion (0.25 mg/h: from 53.1 +/- 11.3 to 22.1 +/- 9.3 pg/ml; 0.50 mg/h: 62.1 +/- 14.4 to 17.9 +/- 7.9 pg/ml), but they remained significantly elevated in the untreated control patients. Vasopressin plasma level increased only in the control group (p < 0.01) and decreased in the patients in whom 0.50 mg/h of enalaprilat was infused.(ABSTRACT TRUNCATED AT 250 WORDS)

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