Search PubMed⌕ Search

Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 289 records · Page 16Linked to original sources
PubMed1993

The influence of intravenous anaesthetics on polymorphonuclear leukocyte function.

Polymorphonuclear leukocytes (PMNL) play a vital role in the defence against invading bacteria. It is known that some anaesthetics inhibit PMNL function and, thus, possibly enhance perioperative infection. We investigated the effect of methohexitone, flunitrazepam, and droperidol on three bactericidal PMNL functions, i.e., superoxide anion production, hydrogen peroxide generation, and activity of released myeloperoxidase, in vitro. Approved photometrical assays were used. Superoxide anion was measured by the reduction of cytochrome C, hydrogen peroxide by the horse radish peroxidase catalysed oxidation of phenol red, and myeloperoxidase by the turnover of 2,2'-azino-di(3-ethylbenzthiazoline) sulfonic acid. Methohexitone (P < or = 0.001) and flunitrazepam (P < or = 0.01) inhibited superoxide anion production, and methohexitone (P < or = 0.01) reduced hydrogen peroxide generation but only at concentrations beyond clinical relevance. Droperidol did not cause any alteration of the PMNL functions tested. Consequently, it seems unlikely that the usual doses of methohexitone, flunitrazepam, or droperidol promote bacterial infections in vivo by impairing the activity of myeloperoxidase or by inhibiting the generation of superoxide anion or hydrogen peroxide.

Adult↗
PubMed1993

Platelet function in cardiac surgery: influence of temperature and aprotinin.

Hypothermic cardiopulmonary bypass (CPB) has been associated with both coagulation defects and hemorrhage. The influence of temperature on platelet function and the benefits of aprotinin in this situation were studied in 60 patients undergoing elective aortocoronary bypass grafting. The patients were randomly divided into four groups (15 patients per group): group 1, normothermic CPB (nasopharyngeal temperature > 34 degrees C); group 2, normothermic bypass and administration of high-dose aprotinin (2 million IU before CPB, 500,000 IU/h until the end of the operation, and 2 million IU added to the prime); group 3, hypothermic CPB (nasopharyngeal temperature < 28 degrees C); and group 4, hypothermic CPB and aprotinin. Platelet function was evaluated by aggregometry (turbidimetric technique), and aggregation was induced by adenosine diphosphate (1 and 2 mumol/L), collagen (4 micrograms/L), and epinephrine (25 mumol/L) before, during, and after CPB into the first postoperative day. Starting from comparable baseline values, maximum platelet aggregation and maximum gradient of platelet aggregation were significantly most reduced after CPB in group 3 (hypothermic CPB without aprotinin) (ranging from -30% to -53% relative to baseline values). In comparison with the other groups, platelet function in this group also recovered less quickly in the later post-bypass period. Hypothermic CPB with aprotinin resulted in less-altered platelet function than hypothermic CPB without aprotinin. Platelet aggregation in aprotinin-treated patients was comparable overall with that in patients undergoing normothermic CPB. On the first postoperative day, aggregation variables had returned to or exceeded baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Aprotinin↗
PubMed1993

Aprotinin in pediatric cardiac operations: platelet function, blood loss, and use of homologous blood.

Excessive hemorrhage secondary to cardiopulmonary bypass may be encountered after pediatric cardiac operations. Platelet dysfunction appears to be especially responsible for this problem. The proteinase inhibitor aprotinin is suggested to possess platelet preservation properties and reduce blood loss in this situation. The effects of aprotinin (25,000 U/kg after induction of anesthesia, 25,000 U/kg added to the prime, 25,000 U/kg every hour of cardiopulmonary bypass) on platelet function were randomly studied in 12 children with a weight of less than 10 kg (group 2) and 12 children weighing more than 10 kg (group 4), who were compared with two groups of children without aprotinin (group 1, < 10 kg; group 3, > 10 kg). Twelve children undergoing major vessel operations without cardiopulmonary bypass and aprotinin served as a control. Platelet function was assessed using aggregometry (turbidometric technique with adenosine diphosphate, 2.0 mumol/L; collagen, 4 micrograms/mL; epinephrine, 25 mumol/L; NaCl [control]). Platelet function was not altered in the control patients within the entire investigation period. Maximum aggregation in the small children was already lower at baseline in comparison with that of the children > 10 kg. Cardiopulmonary bypass was followed by a significant reduction in platelet aggregation in all groups. Treatment with aprotinin did not improve platelet function (maximum aggregation and maximum gradient of aggregation) in any group. On the first postoperative day, maximum aggregation in the small children exceeded baseline values, whereas in both groups of children > 10 kg baseline values had almost been established. Postoperative blood loss was not reduced by treatment with aprotinin.(ABSTRACT TRUNCATED AT 250 WORDS)

Aprotinin↗
PubMed1993

Intercostal nerve block, interpleural analgesia, thoracic epidural block or systemic opioid application for pain relief after thoracotomy?

The purpose of this study was to investigate the effect of different pain-relief methods (regional and systemic) following thoracotomies on the cardiovascular system, pulmonary gas exchange, various endocrine parameters and subjective perception. A further aspect was to evaluate the benefits of interpleural analgesia as a new regional technique against already established regional techniques, such as intercostal nerve block and thoracic epidural block. All postoperative pain methods led to a significant time-dependent reduction of the adrenaline concentrations in plasma while the noradrenaline concentrations did not change significantly. There were no statistical differences in catecholamine concentrations among the different study groups, although the mean concentrations of adrenaline in patients having a thoracic epidural block for pain relief were lower in comparison to the findings in other groups. The plasma concentrations of the "stress metabolites", such as glucose, free fatty acids and lactate, as well as the haemodynamic (mean arterial pressure, heart rate) and pulmonary parameters (blood gas analyses), showed no significant differences among groups. In contrast to the other pain-relieving methods, interpleural analgesia did not lead to sufficient pain relief in that 7 out of 10 patients needed supplementary systemic opioid therapy. Therefore, interpleural analgesia for pain relief following thoracotomies cannot be recommended.

Adrenocorticotropic Hormone↗
PubMed1993

[Indications for the use of human albumin in anesthesia and intensive care medicine].

The plasmatic albumin concentration (3.5-4.5 g/dl) represents about 60% of the total plasma protein. Only 25-40% of whole albumin belongs to the intravascular pool, the majority is distributed in the interstitial space especially of the skin. Main physiological effects of plasmatic albumin are the control of the plasmatic volume by preservation of the colloid oncotic pressure (COP) and the plasmatic transport including the binding of drugs. The COP is the main factor for fixation of the intravascular volume and the prevention of interstitial oedema. The acute volume effects of albumin can be totally replaced by synthetic colloids like hydroxyethyl starch, gelatine, and dextran, with the exception of volume substitution in neonates. In intensive care medicine, the COP-effects of albumin can almost be replaced by synthetic colloids as well. A positive COP-effect by administration of human or synthetic macromolecules is unlikely in patients with capillary leak. For therapy control, the direct measurement of COP is superior to the calculation derived from albumin or total protein. The global clinical situation of the patient and the course of haematocrit should be respected as well. For prevention of interstitial pulmonary oedema, a COP of 15-20 mmHg should be achieved. Up to now, no clinical study verified a positive effect of albumin substitution regarding outcome or incidence of complications in intensive-care patients. Thus, an albumin therapy to maintain a COP of 15-20 mmHg in intensive-care patients is only recommended if a capillary leak is unlikely and the dose limits of synthetic colloids are attained.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1993

[Anesthesia in familial hyperkalemic periodic paralysis].

A 53-year-old woman was scheduled for elective surgery of a L4-L5 lumbar disc prolapse. Preoperatively, she reported of a hereditary muscle disease in her family which could be identified as familial hyperkalaemic periodic paralysis. In patients with familial periodic paralysis, only limited information is available in the current anaesthesiological literature. This is especially true of the hyperkalaemic form which was separated from the hypokalaemic form in 1957. Most patients suffering from periodic paralysis will develop myotonic symptoms in time, but evidence is lacking that the incidence of malignant hyperthermia (MH) is higher than in normals. However, abnormalities of the electrocardiogram (ECG) due to changes in the potassium serum levels are not unusual, and the anaesthesiologist must be aware of cardiac arrhythmias. In the present case, the patient was anaesthetized using fentanyl, midazolam, and vecuronium, and ventilated with 66% nitrous oxide in oxygen. Radial artery blood pressure, end-tidal CO2, and nasopharyngeal temperature were monitored continuously. Surgery was completed after 2 hours with no abnormalities in the intraoperative course. Recovery from anaesthesia was uneventful. During the postoperative follow-up for 1 week, further attacks of paralysis, intermittent sodium-potassium imbalance of the muscle cell membrane appears to be the primary pathogenetic factor. In this special disease, prevention of carbohydrate depletion and the avoidance of muscle relaxants are recommended in the anaesthesiological literature. However, a specified regimen of general anaesthesia has not yet been outlined. In our special case, the use of anaesthetics deemed to be safe in MH susceptible patients produced an uneventful perioperative course.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1993

[Anesthesia for patients with pheochromocytoma. Our own results and a review].

Phaeochromocytoma is a rare, autonomous catecholamine secreting tumour of the sympatho-adrenergic system. Due to the continuous or phasic secretion of catecholamines from the tumour, patients present with hypertensive crisis, episodic or sustained hypertension or arrhythmia. Excessive intraoperative hypertension unable to control by usual methods should be considered to be a phaeochromocytoma. Surgical removal of identified lesions should be performed under controlled conditions and after sufficient preparation of the patient. Preoperative alpha-adrenergic blockade with prazosin and phentolamine allows an increase in intravascular volume and affords some protection against excessive intraoperative hypertension. The use of beta-adrenergic antagonists is only recommended in patients with arrhythmia (especially tachycardia) and after induction of alpha-adrenergic blockade. For operation of phaeochromocytoma, modified neuroleptic anaesthesia is a useful anaesthetic technique. Intraoperative hypertension is controlled with sodium nitroprusside and phentolamine. Intravascular volume is substituted under CVP or PAP control, and epinephrine or norepinephrine are used if necessary. During the postoperative period, hypotension or hypertension or left ventricular failure may occur. In an own study, 9 patients with phaeochromocytoma were investigated, 7 patients with other operations of the adrenal glands served as controls. Despite specific preoperative preparation and intraoperative use of antihypertensive drugs, excessive increases in blood pressure could not be avoided in some cases. Extremely high plasma levels of catecholamines up to the factor 1,000 of the normal range were found. Even in controls, considerable increases in blood pressure and catecholamine levels were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Volume replacement with hydroxyethyl starch solution in children.

In 30 consecutive children undergoing cardiac surgery, two different types of fluid were given randomly for volume replacement in the pre-bypass period. In group 1 (n = 15), low molecular weight hydroxyethyl starch solution (LMW-HES) (6% HES; mean molecular weight 200,000 Da, molar substitution 0.5) and in group 2 (n = 15) 20% albumin (HA) was infused from the induction of anaesthesia until the start of cardiopulmonary bypass (CPB). In addition to haemodynamic values, various laboratory variables were measured before and after CPB until the morning of the 1st day after operation. The patients did not differ in diagnosis and conduct of CPB (lowest rectal temperatures: group 1 29.0 (SD 1.1) degrees C; group 2 29.4 (1.0) degrees C). Haemodynamic data (MAP, HR, CVP), anti-thrombin-III, fibrinogen, platelet count and coagulation variables were comparable between the groups until the 1st day after operation. Postoperative blood loss and the use of homologous blood or blood products were similar in all children. Albumin concentration increased after infusion of albumin (35-47 g litre-1) and was significantly greater until the end of the operation compared with the LMW-HES-treated children. Colloid osmotic pressure, however, was similar in the two groups and returned to baseline values on the 1st day after operation (LMW-HES group 19.31 (1.2) mm Hg; HA group 18.0 (1.3) mm Hg). Post-bypass urine output and creatinine values also did not differ between the groups. Anaphylactic reactions were not observed in any of the patients. It can be concluded that LMW-HES solution can be used effectively and safely for volume replacement in the pre-bypass period in small children undergoing cardiac surgery.

Antithrombin III↗
PubMed1993

Does correction of acidosis influence microcirculatory blood flow during cardiopulmonary bypass?

We studied 15 patients undergoing cardiopulmonary bypass (CPB) to examine the effect of response to correction of acidosis on microcirculatory blood flow. Acidosis was defined when base excess was less than -10.0 mmol litre-1 while carbon dioxide partial pressure was within the normal range. CPB was carried out at almost normothermic temperature (smallest rectal temperature 35.2 (SD) 0.4 degrees C). Sodium bicarbonate (NaHCO3) was given to correct acidosis during steady state CPB. Skin microcirculatory blood flow was assessed using a double-channel laser Doppler flow (LDF) monitor. LDF was measured on the patient's forehead and forearm before infusion of NaHCO3 (baseline) and 30 s, 1, 3, 5, 7, 10 and 15 min later. Skin, blood, rectal and nasopharyngeal temperatures did not change during the investigation. Plasma viscosity, haemoglobin and carbon dioxide partial pressure also remained unchanged. Mean arterial pressure (MAP) and systemic vascular resistance (SVR) decreased slightly after infusion of NaHCO3 (MAP -29%; SVR -32%). A total of NaHCO3 99.4 (4.4) mmol litre-1 was given for correction of acidosis. pH and HCO3- were within the normal range shortly after the infusion of NaHCO3. LDF measured on both the forehead (+49%) and the forearm (+29%) increased significantly after infusion of NaHCO3. Changes in pH correlated positively with changes in LDF (analyses of co-variance, P < 0.02), but haemodynamic and other laboratory values did not correlate with LDF. We conclude that the microcirculatory response to correction of acidosis with NaHCO3 during CPB can be monitored using skin laser Doppler flowmetry. Infusion of NaHCO3 resulted in a significant improvement in skin microcirculatory perfusion.

Acidosis↗
PubMed1993

Circulatory effects of the PDE-inhibitors piroximone and enoximone.

1. The isolated circulatory response to intravenous application of the phosphodiesterase (PDE) inhibitors piroximone and enoximone was studied. 2. In a randomized sequence of 30 male patients undergoing elective aortocoronary bypass grafting either piroximone (0.5 mg kg(-1); n = 10) or enoximone (0.5 mg kg(-1); n = 10) were given during steady state of cardiopulmonary bypass (CPB). A group in which NaCl was given as a placebo served as a control (n = 10). 3. MAP was reduced by piroximone (maximum -23 mm Hg) and enoximone (maximum -18 mm Hg), whereas it increased in the control (+20 mm Hg). Volume of the extracorporeal circuit indicating venous pooling decreased more pronouncedly in the enoximone patients (-440 ml) than in the piroximone group (-300 ml). 4. Laser Doppler flows (LDFs) increased in both PDE-III inhibitor groups with the higher and longer increase in the enoximone-treated patients (LDF-forehead maximum +44%, LDF-forearm maximum +33%). Piroximone-induced increase in both LDFs was less pronounced with respect to both time and degree (LDF-forehead maximum +30%, LDF-forearm +12%). 5. Oxygen consumption (VO2) was significantly higher in the PDE-III inhibitor-treated than in the control patients. 6. Piroximone and enoximone showed significant vasodilatory properties at the arterial and venous side (= 'venous pooling'), from which patients with heart failure would profit. 7. Vasodilation could be observed for a longer period and was more pronounced in the enoximone-treated than in the piroximone patients. Alterations in capillary skin blood flow measured by laser Doppler technique gave evidence for an improvement in nutritive microcirculation, which was slightly more pronounced in the enoximone patients.

Aged↗
PubMed1993

The influence of fentanyl and alfentanil on functions of human polymorphonuclear leukocytes in vitro.

Polymorphonuclear leukocytes (PMNL) play an important part in protecting against invading bacteria. It is known that some anaesthetics may impair PMNL functions, thus possibly promoting infection. We investigated the effect of fentanyl and alfentanil on superoxide anion production, hydrogen peroxide generation, and activity of released myeloperoxidase in vitro. However, the two opioids did not have any significant influence on the tested PMNL functions.

Adult↗
PubMed1993

Influence of different glucose-insulin-potassium regimes on glucose homeostasis and hormonal response in cardiac surgery patients .

Intravenous infusion of glucose/insulin in combination with potassium (GIK) is an often used technique to improve myocardial preservation in cardiac surgery. In a randomized study in 50 patients undergoing elective aortocoronary bypass grafting with good ventricular function, the influence on glucose homeostasis and hormonal response to four different glucose/insulin regimes were compared to an untreated control: 1) 50 g of glucose mixed with 100 U of human insulin (HI/100); 2) 50 g of glucose mixed with 100 U of bovine insulin (BI/100); 3) 50 g of glucose mixed with 50 U of human insulin (HI/50); and 4) 50 g of glucose mixed with 50 U of bovine insulin (BI/50) [corrected]. Glucose/insulin were given in combination with 70 mmol of potassium 40 min before beginning the operation. In addition to blood glucose concentrations various endocrine variables were studied before, during and after cardiopulmonary bypass (CPB). Hemodynamic data (arterial blood pressure, heart rate, cardiac index, systemic vascular resistance) were similar in all five groups. Inotropic support after CPB was necessary in none of the patients. Blood glucose levels showed no differences among all GIK groups (groups 1-4) but were significantly higher than in the control patients. The incidence of severely reduced (< 50 mg/dL) or elevated blood glucose level (> 300 mg/dL) did not differ between HI- and BI-treated patients but was significantly lower in the untreated control. Insulin plasma level increased significantly after infusion of GIK with higher levels in HI- than BI-treated patients (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Influence of different intravascular volume therapies on platelet function in patients undergoing cardiopulmonary bypass.

The influence of four different kinds of intravascular volume replacement on platelet function was investigated in 60 patients undergoing elective aortocoronary bypass grafting using cardiopulmonary bypass (CPB). In a randomized sequence, high-molecular weight hydroxyethyl starch solution (HMW-HES, mean molecular weight [Mw] 450,000 d), low-molecular weight HES (LMW-HES, Mw 200,000 d), 3.5% gelatin or 5% albumin were infused preoperatively to double reduced filling pressure (pulmonary capillary wedge pressure [PCWP] < 5 mm Hg). Fifteen untreated patients served as a control. Platelet function was assessed by aggregometry using turbidometric technique (inductors: ADP, epinephrine, collagen). Maximum aggregation, maximum gradient of aggregation, and platelet volume were measured before, during, and after CPB until the first postoperative day. HMW-HES 840 +/- 90 mL, LMW 850 +/- 100 mL, gelatin 950 +/- 110 mL, and albumin 810 +/- 100 mL were given preoperatively. Maximum platelet aggregation (ranging from -23% to -44% relative from baseline value) and maximum gradient of platelet aggregation (ranging from -26% to -45% relative from baseline values) were reduced only in the HMW-HES patients. After CPB, aggregometry also was impaired most markedly in these patients. The other volume groups showed less reduction in platelet aggregation and were similar to the untreated control. On the first postoperative day, aggregation variables had returned almost to baseline in all patients. Platelet volume was the same among the groups within the investigation period. Postbypass blood loss was highest in the HMW-HES group (890 +/- 180 mL). There was significant (P < 0.04) correlation in this group between blood loss and change in platelet aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Comparison of two aprotinin dosage regimens in pediatric patients having cardiac operations. Influence on platelet function and blood loss.

Only a few studies have reported on the effects of aprotinin in pediatric cardiac surgery, and the correct dose is controversial. In a prospective, randomized study, three groups of children weighing less than 20 kg were investigated. In group 1 (n = 14): aprotinin 20,000 U/kg was given after induction of anesthesia, 20,000 U/kg was added to the prime, and another 20,000 U/kg was given every hour of cardiopulmonary bypass (low-dose regimen). In group 2 (n = 14) aprotinin 35,000 U/kg was given after induction followed by an infusion of 10,000 U/kg.min until the end of the operation and 35,000 U/kg was added to the prime (high-dose regimen). In group 3 (n = 14) no aprotinin was used (control). Platelet function was evaluated by aggregometry (maximum platelet aggregation, maximum gradient of platelet aggregation) by means of turbidometric technique (inductors: adenosine diphosphate, collagen, and epinephrine) before and after cardiopulmonary bypass until the first postoperative day. Platelet aggregation was significantly reduced during and after bypass, values ranging from -29% to -54% (maximum aggregation) and -25% to -75% (maximum gradient of aggregation) with regard to baseline values. In the further postoperative course, platelet function recovered and mostly exceeded baseline values on the first postoperative day. Platelet aggregation variables were without any differences among aprotinin-treated and control patients. Blood loss was similar for all three groups and added up to approximately 28 ml/kg until the first postoperative day. The use of packed red cells was also comparable for the three groups, whereas the use of fresh frozen plasma was highest in group 1 (1680 ml until the first postoperative day). We conclude from this study that aprotinin did not improve platelet function and did nor reduce blood loss or the need for homologous blood transfusion in pediatric cardiac surgery, regardless of whether a low-dose or a high-dose regimen was used.

Aprotinin↗
PubMed1993

[Colloidal hypertonic solutions in cardiac surgery].

The ideal solution for volume therapy is still under discussion. In cardiac surgery, hemodynamic efficacy as well as the influence of cardiopulmonary bypass (CPB) are of major interest when administering volume. Hypertonic sodium (HS) solutions which have been advocated for resuscitation from hemorrhagic shock may also be of benefit in cardiac surgery patients. Hypertonic saline solution (7.5%) prepared in 6% hydroxyethyl starch solution (HS-HES) were infused in patients undergoing aortocoronary bypass grafting to double reduced baseline pulmonary capillary wedge pressure (PCWP < 4 mmHg). Volume replacement was carried out before (within 15 min), during (within 2 min), and after CPB (within 15 min). Significantly less HS-HES solution than standard 6% HES solution was necessary to double baseline PCWP. Cardiac index (CI) increased more and systemic vascular resistance (SVR) decreased more pronounced in the HS-HES group than in the 6% HES-patients. Fluid requirements in the patients having received hypertonic solution preoperatively were significantly less during CPB. Pulmonary function (paO2, Qs/Qt) was less changed in the HS-HES patients indicating avoidance of (interstitial) fluid overload in these patients. Infusion of HS-HES after weaning from CPB resulted in overall more improved hemodynamics than volume replacement with 6% HES. Rapid infusion of HS-HES during CPB (within 2 min) was followed by a significant, but shortlasting decrease in MAP (-40 mm Hg) and an increase in the oxygenator volume. Preoperative infusion of HS-HES resulted in a significant improvement in skin capillary microcirculation assessed by lased Doppler technique during and after CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Volume↗
PubMed1993

What is the place of the phosphodiesterase inhibitors?

Pharmacological support is often required during and after weaning from cardiopulmonary bypass. Most standard therapy acts on alpha-, beta- or dopaminergic-receptors, but down-regulation of beta-receptors has led to the development of agents which act independently from the beta-receptor. The phosphodiesterase (PDE) III inhibitor enoximone, was evaluated in cardiac surgery. Application of enoximone prior to weaning from CPB improved overall cardiac function, reduced the need for catecholaminergic inotropic support, and provided increased organ perfusion even 2 h after the operation. 'Pre-treatment' with enoximone may be beneficial, due to its ability to combine inotropic support with systemic and pulmonary vasodilatation, and may be considered as a first-line approach instead of catecholamines.

Cardiac Surgical Procedures↗