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Biomedical subjects

H Böhrer

Publications and source records attributed to H Böhrer.

At least 91 records · Page 5Linked to original sources
PubMed1995

Gastric tonometry: effect of sucralfate on calculated intramural pH.

Tonometric measurement of gastric intramural pH (pHi) is a noninvasive method to assess adequacy of splanchnic perfusion. Calculation of pHi may be influenced by various factors. This prospective study was designed to determine if stress ulcer prophylaxis with sucralfate interferes with pHi measurement. Twenty-five adult patients admitted to the intensive care unit (ICU) after open heart surgery were studied. Nasogastric tonometers were placed. Patients received sucralfate 1 g via the nasogastric tube 8 hours after termination of surgery, thereafter every 6 hrs. Gastric luminal pH and intramural pH were determined immediately prior and 1 hour after the first sucralfate administration. Gastric intramural pH was calculated from the arterial HCO3- concentration and the tonometrically determined intraluminal PCO2 value using the Henderson-Hasselbalch equation. Intraluminal PCO2(ss) was measured to 6.86 +/- 0.75 kPa prior to sucralfate administration as compared to 6.96 +/- 0.68 kPa 1 hour after 1 g sucralfate (P = 0.92). Intramural pH, as calculated by tonometry, was 7.31 +/- 0.05 vs 7.31 +/- 0.05, and was thus not influenced by sucralfate administration (P = 0.97). Mean gastric intraluminal juice pH was 4.2 +/- 1.3 compared to 4.2 +/- 1.2 (P = 0.59). These data suggest that sucralfate does not interfere with tonometrically determined intraluminal PCO2 measurement and calculation of gastric intramural pH.

Aged↗
PubMed1995

Comparative effects of atracurium and vecuronium on intraocular pressure.

The non-depolarising muscle relaxants atracurium and vecuronium have been found to exert variable effects on intraocular pressure (IOP). The aim of the present study was to assess the influence of atracurium and vecuronium on IOP under standardized clinical conditions. A total of 40 patients undergoing ophthalmic surgery were randomly allocated to 2 study groups. Following oral premedication with dipotassium clorazepate (0.3 mg/kg), anaesthesia was induced with thiopentone (3-4 mg/kg) and alfentanil (15 micrograms/kg). Muscle relaxation was provided according to randomisation, with patients in group 1 receiving 0.3 mg/kg atracurium and patients in group 2 0.07 mg/kg vecuronium. Anaesthesia was maintained with isoflurane (0.5-0.8 vol%) and 70% nitrous oxide in oxygen. The trachea was intubated 4 min after induction and muscle relaxation. A total of nine measurements of IOP were taken in each patient, starting before premedication and ending 5 min after endotracheal intubation. In both groups, there was a significant decrease in IOP after induction of anaesthesia with thiopentone, alfentanil, and atracurium or vecuronium. No difference in IOP was found between the groups. We conclude that both muscle relaxants can be given when increases in IOP have to be avoided.

Aged↗
PubMed1994

Hemodynamic and respiratory effects of pneumoperitoneum and PEEP during laparoscopic pelvic lymphadenectomy in dogs.

Extended laparoscopic operations are being performed increasingly in high-risk patients. To assess the effects of increased intraabdominal pressure (IAP) and positive end-expiratory pressure (PEEP) on the hemodynamic and respiratory system during extended procedures a carbon dioxide pneumoperitoneum was artificially induced in 10 dogs undergoing laparoscopic pelvic lymphadenectomy. An increase in IAP up to 15 mmHg had no negative effect on the cardiovascular system. However, the combination of an increased IAP (10-15 mmHg) with PEEP (8 cmH2O) markedly depressed the hemodynamic variables. Measurement of arterial carbon dioxide and fractional end-tidal carbon dioxide revealed significant CO2 retention. We conclude from the results that laparoscopic pelvic lymphadenectomy should be performed in high-risk patients only under general anesthesia with expanded cardiopulmonary monitoring.

Animals↗
PubMed1994

Bolus injection of thrombolytic agents during cardiopulmonary resuscitation for massive pulmonary embolism.

Thrombolytic therapy has proved to be efficacious in the treatment of massive and fulminant pulmonary embolism (PE), but thrombolysis has been considered as contraindicated during cardiopulmonary resuscitation (CPR). This review on the administration of thrombolytic agents in patients who have suffered massive PE necessitating CPR summarises 14 anecdotal reports and three case series involving 34 patients. The case series revealed an overall initial survival rate of 55-100% following bolus administration of thrombolytic agents. In general, bleeding complications were managed conservatively. The establishment of the diagnosis may be feasible using echocardiography or bedside angiography during CPR. However, therapeutic measures should be taken without delay; the patient's history and the clinical picture may thus be the only diagnostic criteria. Even where myocardial infarction is misinterpreted as PE during CPR, bolus injection of a thrombolytic agent can be an appropriate therapeutic option. An alternative may be mechanical catheter fragmentation of the thrombus with subsequent local thrombolysis. Surgery may be restricted to hospitals with ready access to extracorporeal circulation. We conclude that early administration of thrombolytic agents during PE necessitating CPR may help to reduce mortality. We favour the administration of urokinase (2- to 3,000,000-U bolus) or rt-PA.

Adult↗
PubMed1994

[Anesthesia in carotid surgery].

Carotid endarterectomy has become a standard surgical procedure in the therapy of cerebrovascular insufficiency. An important consideration in this form of therapy is to maintain a low perioperative morbidity and mortality. In planning the procedure the two most frequent complications deserve special consideration. Thromboembolism is the major cause of new neurological deficits and prevention should be emphasized as therapeutic interventions are of limited value. The cardiovascular status needs special attention, since the long-term prognosis is predominantly influenced by concomitant coronary artery disease. Regional anaesthesia provides good cardiovascular stability and the chance to monitor neurological changes in an awake patient. Patient discomfort and limited control of vital functions are obviated by general anaesthesia raising the challenge of maintaining cardiovascular stability and establishing adequate cerebral monitoring. Both electroencephalography and somatosensory evoked potentials monitor cerebral function continuously and enable detection of cerebral ischaemia secondary to inadequate blood flow. Another continuous technique is transcranial Doppler sonography; this, however, does not monitor brain function and its role in carotid surgery is still under investigation. Carotid stump pressure or cerebral blood flow measurements provide intermittent data and should therefore only be used as an adjunct. The goal to find an approach that minimizes the risk for the individual patient can only be attained by close cooperation between anaesthesiologists and surgeons.

Anesthesia, General↗
PubMed1994

Midazolam is metabolized by at least three different cytochrome P450 enzymes.

Distribution volumes and metabolism determine the pharmacokinetics of midazolam. Cytochrome P450 3A4 has been considered a significant enzyme in its metabolism. Using heterologously expressed cytochrome P450 enzymes, we have confirmed the additional involvement of cytochromes P450 3A3 and 3A5 in the hydroxylation of the midazolam. Whereas cytochrome P450 3A3 metabolized midazolam to the same extent as cytochrome P450 3A4, cytochrome P450 3A5 increased its metabolism by a factor of 2.7. The relationship of alpha- to 4-hydroxylation of midazolam was approximately 1.3 for cytochromes P450 3A3 and 3A4, and approximately 8.8 for 3A5. The primary location of cytochromes P450 3A3 and 3A4 is the liver in contrast with cytochrome P450 3A5, which occurs predominantly in the kidney. Therefore, further in vivo study is required to prove conclusively that enzymes in the kidney are involved in the metabolism of midazolam. Nitrendipine itself is metabolized by cytochrome P450 3A enzymes and this was shown to inhibit human liver microsomal hydroxylation of midazolam and preferentially alpha-hydroxylation by about 77%. 4-Hydroxylation was inhibited to 32% of control by nitrendipine. In contrast with inhibition of 4-hydroxylation, alpha-hydroxylation would appear to be competitively inhibited. These findings may be relevant to drug interactions in combined therapy.

Cytochrome P-450 CYP2E1↗
PubMed1994

Prevention of bacterial colonization of intravenous catheters by antiseptic impregnation of polyurethane polymers.

The use of intravascular catheters is associated with infectious complications. Using plastic materials with antibacterial activity may reduce catheter-related bacterial colonization. A novel intravascular catheter impregnated with the antiseptics silver-sulphadiazine and chlorhexidine was tested in an in-vivo model using implantation of catheters into the internal jugular veins of rats. The rate and magnitude of bacterial colonization in groups with implantation of silver-sulphadiazine and chlorhexidine bonded (SSC) and control (C) catheters were assessed 3 and 7 days after intravenous implantation, and local challenge at the exit site by 10(7) cfu Staphylococcus epidermidis ATCC 35984. Significant reductions in the culture positivity of catheters were observed in the test compared with control groups. After 3 and 7 days, the magnitude of bacterial colonization of implanted catheter segments was significantly lower compared with control catheters (P < 0.01). These findings indicate that antiseptic-bonded catheters substantially reduce the incidence and magnitude of catheter-related bacterial colonization, and may subsequently reduce catheter-related infection.

Animals↗