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Biomedical subjects

Wolfgang H Maleck

Publications and source records attributed to Wolfgang H Maleck.

13 recordsLinked to original sources
PubMed2003

Diltiazem may preserve renal tubular integrity after cardiac surgery.

PURPOSE: To evaluate the influence of dopamine and diltiazem on renal function and markers for acute renal failure, including urinary alpha-glutathion s-transferase (alpha-GST), alpha-1-microglobulin (alpha(1)-MG) and N-acetyl-ss-glucosaminidase (ss-NAG) after extracorporeal circulation. METHODS: In a randomized, placebo-controlled, double-blind trial we evaluated the efficacy of dopamine (2.5 micro g x kg(-1) x min(-1)), diltiazem (2 micro g x kg(-1) x min(-1)) or placebo administered over 48 hr postoperatively to maintain renal tubular integrity in 60 elective cardiac surgery patients. alpha-GST, alpha(1)-MG, ss-NAG, and creatinine clearance were measured from urine collected during surgery (T0), the first four hours (T1), 24 hr (T2) and 48 hr (T3) postoperatively. RESULTS: Cumulative urine output in the diltiazem group (9.0 +/- 2.8 L) increased significantly compared with placebo (7.0 +/- 1.6 L), but not compared with dopamine (7.8 +/- 1.8 L). Creatinine clearance showed no significant intergroup differences. In all groups alpha(1)-MG increased from T0 to T3, but we found no significant intergroup differences. alpha-GST increased significantly from T0 to T3 in the placebo (2.1 +/- 1.8 to 11.4 +/- 8.6 micro g x L(-1)) and in the dopamine groups (2.7 +/- 1.8 to 13.6 +/- 14.9 micro g x L(-1)), but not in the diltiazem group (1.8 +/- 1.4 to 3.2 +/- 3.2 micro g x L(-1)). Forty-eight hours postoperatively alpha-GST was significantly lower in the diltiazem group than in both other groups. CONCLUSIONS: Diltiazem stimulates urine output, reduces excretion of alpha-GST and ss-NAG and may be useful to maintain tubular integrity after cardiac surgery.

Acetylglucosaminidase↗
PubMed2003

Rescuer position for tracheal intubation on the ground.

BACKGROUND: Emergency oral tracheal intubations in the pre-hospital setting can be more difficult because the rescuer's position with respect to a patient lying on the ground may not provide optimal conditions for intubation. Since optimal visualisation of the larynx often depends on the force generated during laryngoscopy, we measured the pressure required for intubation (P(i)) as well as the maximum pressure (P(max)) that can be generated with the laryngoscopy blade in seven intubator positions. METHODS: Nineteen hospital personnel with intubation experience participated in this study. A modified #3 Macintosh laryngoscope blade was used to measure the pressure exerted on the tongue of a manikin placed on the ground during intubation. The following positions were studied: standard, sitting, prone, kneeling, left and right lateral decubitus and straddling. RESULTS: Intubating in the straddling position required the lowest P(i), as a percent of P(max) (68+/-14%). This was significantly less than the prone, right lateral decubitus and sitting positions. (Tukey's W procedure, P<0.05) CONCLUSION: The straddling position affords the intubator significantly more reserve force than the prone, right lateral decubitus or sitting position. We suggest that the straddling position may be an advantageous position for pre-hospital intubations especially when visualisation of the glottis is difficult.

Adult↗
PubMed2003

Effect of in vitro hemodilution with hydroxyethyl starch and dextran on the activity of plasma clotting factors.

OBJECTIVE: A recent thrombelastography study indicated a compromised in vitro blood coagulation after 10:10 (equal parts of blood and infusion) and 10:4 (10 parts blood to four parts infusion) hemodilution with several plasma substitutes. Oncovertin N (Oncovertin) (a 10% dextran 40 solution) had the strongest anticoagulant effect of all solutions tested, and HAES-sterile 10% (HAES) (a 10% hydroxyethyl starch 200/0.5 solution) showed the strongest effect of five different hydroxyethyl starch preparations. The aim of this study was to determine how in vitro hemodilution with HAES and Oncovertin affects the activity of coagulation factors. DESIGN: HAES and Oncovertin were tested to determine the intrinsic effect of colloid molecules, as opposed to hemodilution. Normal saline (NaCl) and nonlactated Ringer solution were used as noncolloidal controls. SETTING: University research institute. PATIENTS: Six healthy volunteers. INTERVENTIONS: Twenty milliliters of blood was obtained from each subject. MEASUREMENTS AND MAIN RESULTS: Prothrombin index, activated partial prothrombin time, soluble fibrin monomers, and the activity of coagulation factors I, II, V, VII, VIII, IX, X, XI, and XII were measured with the Behring Chromotimer according to the manufacturer's instructions. Two dilution ratios of citrated blood to infusion were used: 10:10 (equal parts of blood and infusion) and 10:4 (10 parts blood to four parts infusion). Baseline was undiluted. Hemodilution with NaCl at both 10:4 and 10:10 influenced the coagulation variables measured. The activities of factors I, VII, and soluble fibrin monomers were less influenced than expected by hemodilution alone. The activities of factors II, V, IX, and XI were significantly (p <.04) lower with both 10:4 and 10:10 dilution with NaCl. In the assays for factors IX, XI, and XII, clots formed immediately after adding the appropriate reagents in the presence of Ringer solution at 10:10 hemodilution, so that the activities of those factors could not be measured. For the other factors and for 10:4 dilution, the outcome after Ringer solution was similar to that of NaCl. The activities were less influenced after 10:4 hemodilution with both HAES and Oncovertin than after dilution with NaCl and Ringer solution, with no significant differences from baseline. At 10:10 hemodilution with both HAES and Oncovertin, several factor activities were significantly (p <.04) lower than baseline. CONCLUSIONS: Both NaCl and Ringer solution cause measurable effects on coagulation factors at 10:4 hemodilution that can be explained by hemodilution alone. The effects on clotting factors of 10:4 hemodilution with HAES and Oncovertin were not significant. Even at 10:10 hemodilution with HAES or Oncovertin, the reduction in factor activities, although significantly (p <.04) different from baseline, was less than what was expected by dilution alone.

Blood Coagulation Factors↗
PubMed2002

Dolasetron, but not metoclopramide prevents nausea and vomiting in patients undergoing laparoscopic cholecystectomy.

PURPOSE: Postoperative nausea and vomiting (PONV) is one of the most frequent complications of general anesthesia. The aim of the study was to compare the antiemetic efficacy of dolasetron and metoclopramide after inhalational or i.v. anesthesia (IVA). METHODS: In a randomized, placebo-controlled, double-blinded trial we evaluated the efficacy of 12.5 mg dolasetron i.v. and 20 mg metoclopramide (MCP) i.v. in preventing PONV in 387 patients (ASA I-III) undergoing laparoscopic cholecystectomy. Patients were allocated randomly to one of three main groups: Group D (n = 129) received 12.5 mg dolasetron i.v., Group MCP (n = 129) 20 mg MCP i.v., and Group C (n = 129) saline as placebo i.v. Using a multifactorial study design, one third of each main group (n = 43) was further randomized to receive either general anesthesia with desflurane, isoflurane or IVA with propofol and remifentanil. PONV, postoperative piritramide and droperidol consumption were documented. RESULTS: Independent from the anesthesia regimen chosen, dolasetron reduced PONV (19%) significantly compared to MCP (45%) and placebo (46%). Furthermore we could show a significant difference in the incidence of PONV between IVA (28%) and isoflurane (46%), but not in comparison to desflurane (36%). Patients receiving IVA had a higher postoperative piritramide consumption compared to the two other groups. CONCLUSIONS: The results of our study suggest that dolasetron was more effective than MCP and placebo in preventing PONV. This action is independent of the anesthetic technique used.

Adult↗
PubMed2002

Dolasetron for preventing postanesthetic shivering.

UNLABELLED: We designed this study to assess the efficacy of dolasetron compared with clonidine and placebo in prophylaxis of postanesthetic shivering. We included 90 patients undergoing elective abdominal or urologic surgery. The patients were randomly assigned to one three groups (each group n = 30) using a double-blinded study protocol: Group A received 12.5 mg dolasetron, Group B 3 microg/kg clonidine, and Group C saline 0.9% as placebo. The medication was given after the induction of anesthesia. Postanesthetic shivering was judged by using a five-point scale. In the Clonidine group, 86.6% showed no shivering, whereas in the Dolasetron and Placebo groups, only 63.3% and 66.6%, respectively, were symptom free. Only clonidine, but not dolasetron, significantly reduced the incidence and the severity of shivering. We conclude that clonidine is effective in preventing shivering when given before surgery, whereas dolasetron, at the dose used, is not effective. IMPLICATIONS: Shivering, an irregular muscular fasciculation lasting longer than 15 s, is a common complication secondary to general anesthesia. We compared dolasetron with clonidine (an established antishivering drug) in the prevention of postanesthetic shivering. Dolasetron 12.5 mg was not effective.

Abdomen↗
PubMed2002

The influence of hyperoxic ventilation during sodium nitroprusside-induced hypotension on skeletal muscle tissue oxygen tension.

BACKGROUND: Increasing inspired oxygen concentrations might provide a simple and effective intervention to increase oxygen tension in tissues during controlled hypotension. To test this hypothesis, the influence of hyperoxic ventilation (100% O2) on skeletal muscle oxygen partial pressure (Ptio2) in patients receiving sodium nitroprusside-induced controlled hypotension was studied. METHODS: Forty-two patients undergoing radical prostatectomy were prospectively studied and randomly divided into three groups as follows: (1) Controlled hypotension induced by sodium nitroprusside (mean arterial blood pressure, 50 mmHg) and hyperoxic ventilation (CH-100%; n = 14); (2) controlled hypotension and ventilation with 50% O2 in nitrous oxide (CH-50%; n = 14); and (3) standard normotensive anesthesia with 50% O2 in nitrous oxide (control; n = 14). Ptio2 values were measured continuously in all patients using implantable polarographic microprobes. Arterial blood gases and lactate concentrations were analyzed in 30-min intervals. RESULTS: Surgical blood loss and transfusion requirements were significantly reduced in both groups receiving hypotensive anesthesia. During surgery, arterial partial pressure of oxy-gen and arterial oxygen content were significantly higher in patients of the CH-100% group. Baseline values of Ptio2 were comparable between the groups (CH-50%: 25.0 +/- 0.7 mmHg; CH-100%: 25.2 +/- 0.2 mmHg; control: 24.5 +/- 0.2 mmHg). After a transient increase in Ptio2 in the CH-100% group during normotension, Ptio2 values returned to baseline and remained unchanged in the control group. Ptio2 decreased significantly during the hypotensive period in the CH-50% group. The lowest mean Ptio2 values were 15.0 +/- 4.1 mmHg in the CH-50% group, 24.2 +/- 4.9 mmHg in the CH-100% group, and 23.5 +/- 3.8 mmHg in the control group. There were no significant changes in lactate plasma concentrations in any group throughout the study period. CONCLUSIONS: Hyperoxic ventilation improved skeletal muscle tissue oxygenation during sodium nitroprusside-induced hypotension. This improved local tissue oxygenation seems to be most likely due to an increase in convective oxygen transport and the attenuation of hyperoxemia-induced arteriolar vasoconstriction by sodium nitroprusside.

Aged↗
PubMed2002

Intravenous L-lactate application in minipigs partially protects acetylcholinesteratic but not butyrylcholinesteratic activity in plasma from inhibition by paraoxon.

OBJECTIVE: Intoxications with organophosphorous compounds such as paraoxon, an inhibitor of serine hydrolases, mainly butyrylcholinesterase and acetylcholinesterase, are frequent. Oximes are the only enzyme reactivators clinically available. In vitro studies have shown that L(+)-lactate reduces the inhibition of acetylcholinesteratic (AChEA) and butyrylcholinesteratic activity of plasma (BChEA) by paraoxon. DESIGN: The purpose of this in vivo study was to determine whether intravenous L(+)-lactate application under normoxic/normocapnic/normohydrogenemic conditions is able to protect AChEA and BChEA from paraoxon inhibition. SETTING: University research institute. SUBJECTS: Eighteen female minipigs. INTERVENTIONS: Animals were anesthetized, intubated, and mechanically ventilated. Every animal received 1 mg of paraoxon per kilogram of body weight in 50 mL of saline over 50 mins. In addition to receiving paraoxon, six pigs of 18 received 2.5 g (0.125 g kg-1 of body weight) of intravenous L(+)-lactate in 50 mL of saline over 50 mins, and six other pigs received 10 g of L(+)-lactate (0.5 g kg-1 of body weight), whereas the six remaining served as controls. MEASUREMENTS AND MAIN RESULTS: In central venous blood, plasma acetylcholinesteratic and butyrylcholinesteratic activity were measured before paraoxon (baseline, 0 mins), immediately after paraoxon (50 mins after start), and 110, 170, 230, 290, 530, and 1010 mins after the start of infusion. Although 10 g of intravenous L(+)-lactate application had a statistically significant protective effect in vivo on AChEA, 2.5 g did not. No significant protective effect on BChEA was achieved with either 2.5 g or 10 g of L(+)-lactate. CONCLUSIONS: Ten grams of L(+)-lactate can increase AChEA when administered simultaneously with paraoxon. Further study of the in vivo effects of L(+)-lactate after paraoxon intoxication and a formal comparison with standard oxime therapy seem warranted. Also, methods for achieving a prolonged elevated lactate concentration in vivo should be investigated.

Acetylcholinesterase↗
PubMedDate not supplied

Intravenous pyruvic acid application in minipigs partially protects acetylcholine-esteratic but not butyrylcholine-esteratic activity in plasma from inhibition by paraoxon.

Intoxications with organophosphorus compounds such as paraoxon (POX) are frequent. Oximes are the only enzyme reactivators clinically available. In vitro and in vivo studies have shown that l-lactate reduces the inhibition of plasma acetylcholine-esteratic activity (AChEA) (in vitro and in vivo) and plasma butyrylcholine-esteratic activity (BChEA) (at least in vitro and possibly in vivo) by POX. However, a short infusion of 10 g of lactate was unable to elevate the plasma lactate level for >3 h. In this study we tested a substance related to l-lactate, i.e. pyruvic acid. The purpose of this animal experimental study (female minipigs with historical control group) was to determine in vivo whether intravenous (i.v.) pyruvic acid application under normoxic/normocapnic/normohydrogenaemic conditions is able to elevate blood lactate levels and whether it is able to protect AChEA and BChEA from POX inhibition. Animals were anaesthetized, intubated and mechanically ventilated. Each received 1 mg kg(-1) body wt. of POX in 50 ml of saline over 50 min and 10 g (ca. 0.5 g kg(-1) body wt.) of i.v. pyruvic acid in 50 ml of saline over 50 min. They were compared with a historical control group of six animals that received only 1 mg kg(-1) body wt. of POX in 50 ml of saline over 50 min. In central venous blood measurements of plasma AChEA and BChEA, the measurements were performed before (baseline), immediately after POX (50 min after start) and 110, 170, 230, 290, 530 and 1010 min after the start of infusion. A 10 g aliquot of i.v. pyruvic acid had a statistically significant protective effect in vivo on AChEA but not on BChE activity. Further study of the in vivo effects of pyruvic acid and l-lactate after paraoxon intoxication and a formal comparison with standard oxime therapy seems warranted. Also, a combination therapy with l-lactate and pyruvic acid in vivo should be investigated.

Acetylcholinesterase↗
PubMedDate not supplied

Enzyme reactivator treatment in organophosphate exposure: clinical relevance of thiocholinesteratic activity of pralidoxime.

Organophosphate compounds are responsible for a large number of accidental and/or suicidal exposures and have been used also for warfare and terrorism. The mechanism of toxicity is by inhibition of cholinesterase. Oximes are the only enzyme reactivators clinically available but clinical experience with oximes is disappointing. There is a gap between laboratory data and clinical impression concerning the efficacy of oxime compounds. Oximes are responsible for thiocholinesteratic activity, a spurious signal caused by interaction between pralidoxime and the thiocholine substrate used for photometric enzyme activity determinations. In a prospective, controlled, non-randomized study performed in anaesthetized miniature pigs, we quantified the extent of pralidoxime-induced cholinesteratic pseudo-activity ex vivo (human blood) and in vivo (minipig) in order to be able to correct values obtained by photometric methods. Plasma cholinesteratic activity using two substrates (acetylthiocholine and butyrylthiocholine) was determined in vitro and in vivo in the presence of pralidoxime. Pralidoxime reacts with the substrate (acetyl- and butyrylthiocholine) used for enzyme activity determinations, producing a spurious signal implying cholinesterase activity (even in the absence of plasma and thus of any enzyme). Cholinesterase activities determined photometrically after pralidoxime therapy can be erroneously high. Although in theory this could mislead clinicians into assuming an efficacious therapy, this is unlikely to occur in vivo under normal pralidoxime dosing conditions. To avoid any ambiguity it is recommended that blood be drawn for enzyme activity determinations prior to reactivator use and no less than 1 h after its administration.

Animals↗