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Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 433 records · Page 24Linked to original sources
PubMed1988

[Anesthesia induction agents and granulocyte adherence].

The influence of clinically relevant concentrations of thiopentone sodium, methohexitone, and etomidate on polymorphonuclear neutrophilic granulocyte (PMN) adherence was investigated in vitro by using nylon fibre columns. The three induction agents produced dose-dependently a significant (p less than 0.01) reduction in adherence. This effect is possibly related to increased risk of postoperative bacterial infection. Further studies on this problem are recommended.

Adult↗
PubMed1988

[Heparin elimination and free hemoglobin following cell separation and washing of autologous blood with Cell Saver 4].

Haemoseparation is used for recovery of autologous blood following cardiac surgery protecting patients from various hazards accompanying homologous blood transfusion. Former studies demonstrated that autotransfusion did not increase blood loss after cardiac surgery despite reduced plasma and platelets following centrifugation and washing of oxygenator content. The purpose of our study was to determine the content of heparin and unbound haemoglobin in autologous packed red cells. METHODS. 10 consenting patients undergoing cardiac surgery (table 1) were investigated. Immediately after termination of bypass blood samples were collected from the oxygenator and from autologous blood following concentration and washing with saline solution in the Haemonetics Cell-Saver 4. Contents of haemoglobin, haematocrit, heparin - with and without addition of antithrombine III - and unbound haemoglobin were analysed. RESULTS. Mean duration of extracorporeal circulation was 100.4 minutes. The oxygenators' volume averaged 2089.9 ml blood with a haemoglobin content of 6.7 g/dl and a haematocrit of 20.4%. This was reduced to 660.8 ml autologous blood with a haemoglobin content of 17.9 g/dl and a haematocrit of 57.2% (table 2). The heparin content of the oxygenator blood was 0.47 U/ml without AT III, and with AT III 0.87 U/ml. Autologous blood contained 0.009 U/ml without AT III; with AT III we measured 0.41 U/ml heparin. Unbound haemoglobin content amounted to 11.4 mg/dl in the oxygenator blood and 71.8 mg/dl in the autologous blood (table 3). CONCLUSIONS. Our results demonstrate that autologous blood following concentration and washing of the oxygenator blood with a Haemonetics Cell-Saver 4 contains heparin, but the amount of heparin is not enough to provoke bleeding after retransfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Component Removal↗
PubMed1988

[Effect of continuous mechanical hemofiltration on the pharmacokinetics of antibiotics exemplified by mezlocillin].

Pharmacokinetics of mezlocillin (70 mg/kg as an infusion) were investigated in 8 patients with multiorgan failure undergoing continuous veno-venous haemofiltration (CVVH) due to acute renal failure (HF-group) in comparison to 8 intensive care patients with an uneffected renal system (control group). Mezlocillin concentration were studied in blood, ultrafiltrate and urine (control group). Elimination of mezlocillin was prolonged in the HF-group with a t1/2 of 170 min in comparison to 109 min in the control patients. No relevant absorption at the haemofilter membrane could be observed. With regard to our results a dose reduction and intermittend application of mezlocillin is suggested; in addition, monitoring of drug levels in critically ill patients becomes of increasing interest, especially during haemofiltration.

Acute Kidney Injury↗
PubMed1988

[Behavior of plasma concentrations of prilocaine following intravenous regional anesthesia and their relation to methemoglobinemia].

In a previous investigation we were able to demonstrate quite different methemoglobin levels after axillary plexus blockade on one side and intravenous regional anesthesia (IVRA) on the other using prilocaine (Fig. 1). At that time we tried to explain this observation by prolonged mobilization of the local anesthetic after tourniquet release, causing only minimal stress to the erythrocyte-related reduction system. In order to study prilocaine mobilization after tourniquet release in the upper limb following IVRA, prilocaine and methemoglobin concentrations were measured in 8 patients. All patients received 400 mg prilocaine; IVRA lasted 30 min in all cases. In each patient we inserted an intra-venous line via the cubital vein with its orifice in the region of the venous outflow of the blocked upper extremity (Fig. 2). Simultaneously, blood samples were taken for measurement of plasma prilocaine concentrations in the axillary region of the blocked limb and from the contralateral upper limb. Following tourniquet release, samples were collected at short intervals for 15 min; starting with the 15th min methemoglobin concentrations were also determined for up to 5 h. The results of the outflow and systemic prilocaine concentrations are presented in Figure 3. Remarkable differences in peak prilocaine concentrations (64 micrograms/ml vs 7.9 micrograms/ml after the 1st min) were found during the 3-h study period. The course of methemoglobin formation was similar to that in a group of patients we had studied previously (Fig. 4). Our findings confirm the assumption that the low and plateau-like methemoglobin formation following intravenous regional anesthesia of the arm is the result of delayed prilocaine release.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Conduction↗
PubMed1988

[Reaction of the sympathetic nervous system, cardiovascular parameters and endocrine stress response in disobliterating interventions of the carotid arteries. A comparison of isoflurane anesthesia and modified neurolepto-anesthesia].

In order to investigate whether the increases in mean arterial pressure (MAP) and HR during carotid endarterectomy are due to a systemic, sympathicotonic stress response and to compare two anesthetic regimens for this operation, 20 patients were randomly allocated to the following groups: (1) modified neuroleptanesthesia with midazolam, fentanyl, and vecuronium: and (2) isoflurane anesthesia with vecuronium relaxation. Premedication (pethidine, promethazine) and induction of anesthesia were similar in both groups. The plasma levels of epinephrine and norepinephrine (by HPLC/ECD), ADH, ACTH, and cortisol (by RIA), glucose, lactate, and free glycerol were determined before and after induction of anesthesia, 7 times during the operation, and 30 min after extubation. MAP and HR were measured continuously. Statistical evaluation was undertaken by analysis of variance with repeated measures on 1 factor, considering P values of less than 0.05 as significant. The endocrine parameters failed to show any remarkable increase during the entire operation period. After the end of the operation all hormones rose significantly (P less than 0.001). No correlation was found between plasma catecholamines and increases in MAP and HR. Group levels of norepinephrine and ADH were higher in the isoflurane group (P less than 0.04). It is concluded that cardiovascular reactions during carotid endarterectomy are not caused by systemic stress. Neuroleptanesthesia leads to better stress protection in the postoperative period, while isoflurane anesthesia has some advantages for the intraoperative control of arterial pressure.

Adult↗
PubMed1988

[Effect of pancuronium bromide on the adherence of polymorphonuclear neutrophilic granulocytes in vitro].

Infection is still an important problem following surgery. Polymorphonuclear neutrophil granulocytes (PMN) play a vital role in host defenses against invading bacteria; thus, adverse effects on PMN caused by anesthetic agents are of general interest. In this study, we examined the influence of pancuronium bromide on PMN adherence in vitro. Heparinized venous blood samples were obtained from 18 healthy male adult donors. Each specimen was divided. One part was used to determine the adherence of untreated PMN, while pancuronium bromide was added to the other. Two concentrations (1.3 or 0.5 micrograms relaxant/ml blood) were tested. PMN adherence was studied using nylon fiber columns as described by MacGregor et al. Both concentrations of pancuronium bromide caused an inhibition of adherence, which was significant in the case of the higher dosage (p less than 0.05). There is a direct correlation between the intensity of PMN adherence and the extent of granulocyte delivery to sites of inflammation. Therefore, it seems possible that clinical concentrations of pancuronium bromide may be able to increase the risk of developing bacterial infections. Further studies concerning this problem should be conducted.

Adult↗
PubMed1988

[Tube wall herniation in an Ulmer system as a cause of an intraoperative ventilation disorder].

We report an intraoperative complication caused by nitrous oxide diffusion through the inner layer of a tube of the Ulmer breathing system, which has been developed for ventilation of small children and neonates (Fig. 2a). About 40 min after intubation and mechanical ventilation with oxygen, nitrous oxide, and halothane a sudden rise in PETCO2 was noticed (Fig. 1). Auscultation of both lungs revealed no pathological finding; suction through the endotracheal tube was possible with no indication of endotracheal tube herniation. After reconnection to the ventilator, PETCO2 values again increased. Thorough inspection of the tubes of the Ulmer breathing system revealed a herniation that nearly occluded the lumen (Fig. 2b). After changing the anesthetic system, the operation and anesthesia were continued uneventfully.

Child, Preschool↗
PubMed1987

[Combination autotransfusion in heart surgery. Use of acute normovolemic hemodilution in coronary heart disease].

Normovolemic hemodilution (15 mg/kg body-weight: group I) was undertaken in 100 patients immediately before the start of coronary-artery surgery. In addition, a Cell-Saver (Haemonetics, Munich) was used for intra-operative autotransfusion. Another group of 100 patients (group II) was similarly operated on without autotransfusion (the study was conducted on 200 consecutive patients undergoing aorto-coronary bypass). Before blood (autologous or homologous) was administered a reduction of hemoglobin to 9 g/100 ml and hematocrit to 0.28 was well tolerated (during extracorporeal circulation: 6.5 g/100 ml and 0.16, respectively). Due to intra- and postoperative complications, such as infarct bleeding (including reoperation) or septicemia, the number of patients placed in group I fell to 94, that in group II to 90. Acute normovolemic hemodilution increased cardiac output and oxygen transport capacity, while other hemodynamic parameters remained unchanged, and there was no effect on extravascular lung water. Autotransfusion reduced the need for homologous blood derivatives by 71% (fresh blood, fresh plasma, RBC concentrates). No clinically significant disadvantages occurred.

Adult↗
PubMed1987

Influence of cardiac output on thermal-dye extravascular lung water (EVLW) in cardiac patients.

The influence of varying cardiac output (CO) on thermal-dye extravascular lung water (EVLW) was investigated in a total of 40 cardiac surgery patients before the onset of the operation. EVLW was measured by means of the double indicator dilution technique with indocyanine green as the non-diffusible indicator and a microprocessed lung water computer 15 min and 30 min after change of CO. CO was varied from -45% to +70% of the baseline value by nifedipine infusion (CO increases, n = 20) or halothane application (CO decreases, n = 20), respectively. CO was measured from the femoral artery instream thermistor tipped lung water catheter and, simultaneously, from the pulmonary artery. In spite of a highly significant decrease (-45%) and increase (+70%) in CO no change in EVLW could be observed. CO estimation was comparable for both methods used. Regression analysis revealed no relationship between CO and EVLW as well as between EVLW and various hemodynamic parameters. We conclude that thermal-dye technique for estimation of EVLW may be accurate in spite of changing cardiac output over a wide range.

Cardiac Output↗
PubMed1987

Influence of nimodipine and nifedipine on intrapulmonary shunting--a comparison to other vasoactive drugs.

This study was assigned to investigate the influence of calcium channel blockers (nimodipine and nifedipine) in comparison to other vasoactive drugs (nitroglycerin, dopamine) on pulmonary shunting (Qs/Qt). Fifty anesthetised patients scheduled for aortocoronary bypass operation were randomly allocated to 5 groups receiving one of the following drugs: nimodipine 1.0 microgram X kg-1 X min-1; nifedipine 0.7 microgram X kg-1 X min-1; nitroglycerin (TNG) 0.5 microgram X kg-1 X min-1; dopamine; micrograms X kg-1 X min-1; placebo (0.9% NaCl). Nimodipine as well as nifedipine led to a significant increase in cardiac output (+44%; +39%), pulmonary vascular resistance simultaneously decreased (-25%; -28%). PaO2 increased significantly (+16%; +13%), too, whereas Qs/Qt remained almost unchanged. In contrast, the increase in cardiac output induced by dopamine (+27%) was accompanied by a significant increase in shunting (+34%). TNG application did not alter Qs/Qt, but pulmonary artery pressure (PAP) decreased markedly (-19%).

Blood Pressure↗
PubMed1987

Extravascular lung water and hemofiltration during complicated cardiac surgery.

Hemofiltration (HF) is an established method for treating patients with impaired renal function and excessive fluid retention. In cardiac surgery fluid accumulation during extracorporeal circulation (ECC) may contribute to postoperative organ dysfunction, leading to severe pulmonary insufficiency. In this study our experiences with hemofiltration installed in the cardiopulmonary bypass are demonstrated in patients with preoperative pulmonary edema, impaired renal function, and long-term ECC, proving its efficacy by measurement of extravascular lung water (EVLW) in the early post-bypass period. EVLW-measurement was performed using the thermal-dye technique with indocyanine green and a microprocessed lung water computer. Our data demonstrate that hemofiltration during ECC is a valuable method for controlling fluid balance. It facilitates the intra- and postoperative management of patients with end-stage renal failure or with preoperative pulmonary edema. HF seems to be helpful by decreasing the risk of complications such as fluid overload, which is demonstrated by measurement of EVLW.

Blood↗
PubMed1987

Effects of hypothermia on somatosensory evoked responses in man.

Somatosensory evoked responses after median nerve stimulation were recorded in 21 patients during hypothermic cardiopulmonary bypass. During hypothermia a significant linear correlation (P less than 0.001) was found between evoked potential latency and temperature. Correlation was best for tympanic membrane temperature during cooling and for perfusate temperature (arterial, venous) during rewarming. The increase in latency was more pronounced for middle latency components (N2, N3) and for the early cortical N1 than for the cervical N0 and central conduction time. In all patients N1 was detectable at 26 degrees C, with slightly reduced amplitude. In the rewarming period the changes occurred in the reverse order and pre-bypass values were achieved at normothermia. The slopes of the regression lines were different during cooling and rewarming, when latencies were related to patient (tympanic, nasopharyngeal, rectal) temperature, but identical when arterial or venous blood temperature was used as the reference. No correlation was found between latency and perfusion pressure. We conclude that sophisticated temperature measurement is required to aid the interpretation of evoked responses used during hypothermia.

Aged↗
PubMed1987

Spectral analysis of the EEG during hypothermic cardiopulmonary bypass.

In 39 patients undergoing aorto-coronary-bypass grafting, spectral analysis of the EEG (compressed spectral array: CSA) and calculation of spectral edge frequency (SEF) were performed. The effects of different temperatures and of perfusion pressure (PP) were analyzed. Predictable patterns were observed. During cooling on cardiopulmonary bypass (CPB), linear regression analysis revealed a close correlation between SEF and tympanic membrane (Tty) or nasopharyngeal temperature (Tnp). During rewarming, a nonlinear correlation between SEF and Tty or Tnp was found. Rectal temperature as well as blood temperature in the arterial or venous line of the oxygenator seemed to be less useful. The independence of SEF and PP was demonstrated during the whole procedure. At the onset of CPB, after correction of the aortic clamp for performance of the aortic anastomosis and after removal of the aortic clamp, bilateral EEG slowing of varying duration occurred in 20 patients. Comparison of mean SEF before and after CPB revealed a difference of about 5 Hz. In no patient were major neurological abnormalities observed postoperatively.

Body Temperature↗
PubMed1987

Age and cardiac surgery. Influence on extravascular lung water.

This study was designed in order to evaluate the influence of advanced age on extravascular lung water (EVLW) content. Forty patients undergoing aortocoronary bypass grafting were prospectively divided into two groups according to age below 45 years (group 1; n = 20) and above 65 years (group 2; n = 20). The EVLW was measured using the double indicator dilution technique with indocyanine green as the nondiffusible indicator. Starting from similar baseline values before extracorporeal circulation (ECC), EVLW significantly increased after ECC only in the elderly patients (max + 1.51 ml/kg), whereas lung water content in the other group remained almost unchanged. No significant differences in left ventricular filling pressure (PCP) could be observed. Regression analysis revealed a strong positive correlation between age and increase in EVLW after ECC. Simultaneously, PaO2 was decreased (-114 mm Hg) and intrapulmonary shunt fraction (Qs/Qt) was increased only in this group. Within the next five hours after ECC, lung water returned nearly to baseline values and pulmonary function was normalized. It is concluded that increasing age was associated with a transient increase in EVLW after ECC due to a more pronounced fragility of the pulmonary endothelial membrane or/and to depressed left ventricular performance.

Adult↗
PubMed1987

[Effect of isoflurane and enflurane on somatosensory evoked potentials following stimulation of the median nerve].

The effects of enflurane and isoflurane on somatosensory evoked potentials (SEP) after median nerve stimulation were studied in 25 healthy adult patients. Cervical and cortical SEP were recorded simultaneously. pCO2 and tympanic membrane temperature were kept constant. Following induction of anaesthesia with thiopentone, fentanyl and succinylcholine SEP were recorded during normoventilation with 100% oxygen and after inhalation of 66.6% nitrous oxide. Isoflurane at inspired concentrations of 0.8, 1.65, 2.5, 3.3% was given to 10 patients at 15 minutes intervals and was reduced after nitrous oxide had been replaced by oxygen. 15 patients received equipotent doses of enflurane (1.1, 2.2, 3.25, 4.3%.) SEP were recorded at the end of each interval. Isoflurane and enflurane caused dose dependent increases in latency of the cortical SEP. This effect was more pronounced with enflurane. Isoflurane reduced amplitude of the primary cortical response more than enflurane, when ventilation was performed with 66.6% nitrous oxide in oxygen. High doses of enflurane in oxygen augmented cortical SEP amplitudes associated with a marked increase in latency. Isoflurance and enflurance anaesthesia slightly altered cervical SEP. Middle latency components of the cortical SEP were progressively diminished with increasing isoflurane or enflurane concentrations. The effect of both agents in terms of delayed latencies and reduced amplitudes should be considered when recordings are performed intraoperatively.

Adolescent↗
PubMed1987

[Endocrine stress response in halothane, enflurane and isoflurane anesthesia in surgical interventions].

The endocrine stress response under inhalation anesthesia with halothane, enflurane, and isoflurane was investigated in 30 patients during and after orthopedic surgery (Table 2). Plasma levels of adrenaline and noradrenaline (by HPLC/ECD), ADH, ACTH, and cortisol (by RIA), glucose, lactate, and free glycerol were determined before induction of anesthesia, 10 min after intubation, 10 min before the end of the operation, and 5 and 30 min after extubation. Statistical evaluation was undertaken by analysis of variance with repeated measures on one factor. P values of less than 0.05 were considered significant. There were no significant differences in the concentrations of plasma catecholamines (Table 4, Figs. 1 and 2), ADH, ACTH (Table 5, Figs. 3 and 4), or cortisol before and during surgery between the groups. ADH was lower in the halothane group 5 and 30 min after extubation (P = 0.05), which might be due to the prolonged elimination of halothane after anesthesia. Blood pressure, heart rate (Table 3), and plasma concentrations of glucose, lactate, and free glycerol (Table 6) were comparable in all groups. It is concluded that for clinical practice halothane, enflurane, and isoflurane are comparable in their influence on the surgical stress response.

Adrenocorticotropic Hormone↗
PubMed1987

[Parenteral use of a fat emulsion in the early postoperative period].

Parenteral application of fat emulsions has been established as useful in long term artificial nutrition especially during weaning off the ventilator. In order to ascertain whether these advantages can also be proved in nonventilated patients in the immediate postoperative phase, alternatively carbohydrates versus a new fat emulsion were investigated. 30 patients were randomly allocated to three different nutrition regimens. The caloric and nitrogen supplementation was identical for all groups, while the carbohydrate and fat content was different. Group I: only carbohydrates (as caloric source), group II: high fat load (3 g/kg/day), group III: medium fat dosage (1.5 g/kg/day). Routine laboratory parameters as well as acid-base-status and fat metabolism were evaluated. While most of the routine parameters were not significantly different between the groups, triglyceride levels in serum were highest in group II but never exceeding 280 mg/dl (-x). Nitrogen balance as well as protein metabolism were significantly improved using regimen III, thus documenting the beneficial effect of a medium fat dosage in the immediate postoperative phase. Parenteral nutrition combining amino acids, carbohydrates and a fat emulsion seems to be the optimal postoperative regimen even in patients without ventilatory support.

Abdomen↗