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Biomedical subjects

J Van Hemelrijck

Publications and source records attributed to J Van Hemelrijck.

At least 19 recordsLinked to original sources
PubMed2004

Evaluation of the neuroprotective effects of S(+)-ketamine during open-heart surgery.

UNLABELLED: We compared the effect of S(+)-ketamine to remifentanil, both in combination with propofol, on the neurocognitive outcome after open-heart surgery in 106 patients. A battery of neurocognitive tests was administered before surgery and 1 and 10 wk after surgery. Fourteen patients (25%) in the control group and 10 patients (20%) in the S(+)-ketamine group had 2 or more tests with a cognitive deficit (decline by at least one preoperative SD of that test in all patients) 10 wk after surgery (P = 0.54). Z-scores were calculated for all tests. No significantly better performance could be detected in the S(+)-ketamine group, except for the Trailmaking B test 10 wk after surgery. We conclude that S(+)-ketamine offers no greater neuroprotection compared with remifentanil during open-heart surgery. IMPLICATIONS: N-methyl-D-aspartic acid receptors play an important role during ischemic brain injury. We could not demonstrate that S(+)-ketamine resulted in greater neuroprotective effects compared with remifentanil during cardiopulmonary bypass procedures when both were combined with propofol.

Aged↗
PubMed1999

Is transcranial Doppler useful in the detection of internal carotid artery cross-clamp intolerance?

The aim of this study was to test the hypothesis that a drop in the systolic blood flow velocity in the middle cerebral artery of 70% or more, measured by transcranial Doppler, is a better criteria in the detection of cross-clamp intolerance than electroencephalogram (EEG) and somatosensory evoked potential (SSEP) monitoring. After exclusion of patients with a recent stroke, urgent procedures and combined procedures, a transcranial Doppler with compression test was scheduled in 85 patients. In 13 patients the drop was 70% or more and in these patients a transcranial Doppler was also performed during the reconstruction of the internal carotid artery (the study group) under general anaesthesia. A shunt was used because of EEG and SSEP abnormality in one patient. No changes were observed in the remaining patients and no intraoperative strokes were seen. The transcranial Doppler monitoring was unreliable in three patients. During cross-clamp, the systolic blood flow velocity in the middle cerebral artery dropped less than 70% in four and 70% or more in six patients. It is concluded that using a drop of 70% or more of the systolic blood flow velocity in the middle cerebral artery during internal carotid artery cross-clamp, as an indicator of cross-clamp intolerance, will lead to unnecessary shunting.

Blood Flow Velocity↗
PubMed1995

[Anesthetics: total intravenous anesthesia or inhalation anesthesia in neurosurgery].

In this review article the pro's and contra's of the use of either inhalational or intravenous anaesthetics for neurosurgical procedures are discussed. The objective is to stimulate thoughts concerning controversial subjects, rather than to resolve issues. It is much less complicated to approach the practice of neuroanaesthesia with a few straight forward "rules" based on laboratory measurements (such as intravenous drugs are good because they reduce CBF and ICP, whereas inhalational agents are bad because they increase CBF and ICP). It should also be noted that whereas statements about potential detrimental or beneficial effects of different anaesthetic agents are relatively common, there is a dearth of well-designed prospective studies of sufficient power to substantiate the outcome advantages or disadvantages. The choice of an anaesthetic should include more than just a consideration of the potential intracranial effects of a drug: it should also include experience with a drug and, more important a consideration of the patient as a whole.

Anesthesia, Inhalation↗
PubMed1995

Propofol anesthesia does not inhibit stimulation of cortisol synthesis.

Recent data suggest a negative effect of propofol anesthesia on cortisol secretion. The present study was designed to evaluate the effect of propofol anesthesia on the steroidogenic potential of the adrenal glands. The response of cortisol secretion to stimulation with an adrenocorticotropic hormone (ACTH) analog during intravenous anesthesia with propofol has not been reported before. The response of the secretion of cortisol, 11-deoxycortisol, and 17 alpha-hydroxyprogesterone to tetracosactide stimulation was compared in patients anesthetized with propofol-nitrous oxide (n = 10) or thiopental-isoflurane-nitrous oxide (n = 10) and in normal volunteers (n = 10). The response to tetracosactide was similar in all three groups. An adequate increase in cortisol plasma concentration (more than 7.25 micrograms/dL) was obtained in all subjects except one volunteer. The increase in the plasma concentration of the cortisol precursors was also similar. We were unable to detect any influence of propofol anesthesia on the synthesis of cortisol in response to tetracosactide stimulation.

17-alpha-Hydroxyprogesterone↗
PubMed1994

Relative potency of eltanolone, propofol, and thiopental for induction of anesthesia.

BACKGROUND: The primary purpose of this investigation was to determine the relative potency of eltanolone, a new steroid hypnotic, and propofol and thiopental when used for induction of general anesthesia. In addition, the induction characteristics of propofol and eltanolone were compared. METHODS: One hundred seventy-five patients, premedicated with lorazepam 1 mg orally, randomly received one of six different doses of either eltanolone or propofol. The probability of successful induction (defined as not responsive to verbal commands within 2 min) was related to the logarithm of the dose for each drug by means of logistic regression analysis. Estimates of ED50 and ED95 for each drug were obtained. The incidence of side effects was compared for eltanolone and propofol. The potency of thiopental was determined in a parallel study, using an identical methodology in 105 patients receiving one of seven different doses of the barbiturate. RESULTS: The relative potency of eltanolone was 3.2 times (95% confidence interval 2.7-3.8) greater than propofol and 6.0 times (5.3-6.9) greater than thiopental. ED50 and ED95 values for eltanolone were 0.46 (0.40-0.52) and 0.82 (0.68-1.28) mg.kg-1, respectively. Compared to propofol, induction of anesthesia with eltanolone is characterized by a lower incidence of injection pain (3.5% vs. 58%) and apnea (1.2% vs. 11.2%). CONCLUSIONS: Eltanolone appeared to be an effective induction agent that is 3.2 times more potent than propofol and 6 times more potent than thiopental. Its use was associated with less pain on injection than was propofol.

Adolescent↗
PubMed1994

A comparison of the 2% and 1% formulations of propofol during anaesthesia for craniotomy.

This study investigated the pharmacodynamic and pharmacokinetic equivalence of 1% and 2% propofol emulsions when used for total intravenous anaesthesia for intracranial surgery. The same infusion rate (6.7 mg.kg-1 x h-1) of the two preparations was administered. Induction doses, recovery times, and haemodynamic profiles were identical. Similar propofol concentration profiles were produced and total body clearance of propofol was identical. Both preparations were associated with a similar incidence of injection pain but neither resulted in venous thrombosis or thrombophlebitis at 24 h. Plasma triglyceride concentrations were significantly higher with the 1% solution, but there were no differences in cholesterol concentrations. The 1% and 2% emulsions appeared to be pharmacologically equivalent with similar minor effects on arterial blood pressure and heart rate. Two percent propofol may be preferable to the 1% solution for maintenance of anaesthesia in patients in whom a large lipid load might be considered undesirable.

Adolescent↗
PubMed1994

Carotid artery surgery in the presence of an occlusion of the contralateral carotid artery: perioperative risk analysis and follow-up.

A retrospective study of 129 carotid artery reconstructions with an occlusion of the contralateral internal carotid artery (group CO) is presented. A control group comprised 489 patients with a stenosis of < 50% at the contralateral side (group CN). Both groups had the same mean age. There were fewer women in group CO (14% versus 31%, P < 0.0001), and more patients had a history of coronary heart disease (57% versus 44%, P < 0.05). In addition more patients of group CO had suffered a stroke (36% versus 27%, P < 0.05). A temporary shunt was used selectively and more frequently in group CO (87% versus 31%, P < 0.001). Major postoperative complications occurred with equal frequency in both groups: all strokes plus non-cerebral mortality (total combined morbidity and mortality): 4.65% versus 5.5%. The late incidence of stroke was the same in both groups: 8% in CO and 7% in CN at 5 years. The authors conclude that, under the described circumstances and with the appropriate surgical technique, the presence of an occlusion of the contralateral internal carotid artery does not imply an increase in major postoperative complications nor a higher stroke rate during follow-up.

Aged↗
PubMed1993

Blood pressure management during aortic surgery: urapidil compared to isosorbide dinitrate.

The efficacy and hemodynamic effects of urapidil, an arteriolar vasodilator, and isosorbide dinitrate, a venodilator, were compared, when used for blood pressure control during abdominal aortic surgery. Urapidil is an alpha-adrenergic receptor antagonist with serotonin-1A receptor-agonist activity in the central nervous system. Hemodynamic profiles were recorded before and after the administration of the study drug (+/- 10 minutes before aortic clamping), 3 and 10 minutes following aortic clamping, and before and 3 and 10 minutes following the removal of the aortic clamp. Arterial and mixed venous oxygen contents were compared. Both groups of 18 patients were similar with respect to demographic profiles, anesthetic technique, and perioperative fluid therapy. Identical heart rate and blood pressure profiles were obtained. In contrast to isosorbide dinitrate, urapidil produced a 17% (P < 0.05) increase in cardiac index as a result of a 30% (P < 0.001) decrease in systemic vascular resistance before placement of the aortic clamp. In patients treated with urapidil, cardiac index was higher (P < 0.05) 10 minutes after aortic clamping, before removal of the clamp, and 10 minutes later. The arterio-venous oxygen content difference decreased from 3.2 +/- 0.8 mL O2/dL to 2.4 +/- 1.0 mL O2/dL (P < 0.01) following urapidil, but did not change during the administration of isosorbide dinitrate. It is concluded that urapidil is an effective and safe drug for the prevention of the hemodynamic consequences of aortic clamping. Compared to a venodilator (isosorbide dinitrate), urapidil offers the advantage of improving cardiac output and oxygen delivery.

Alfentanil↗
PubMed1993

Vital organ blood flow during deliberate hypotension in dogs.

Increasing the inspiratory concentration of isoflurane is a commonly used technique for producing deliberate hypotension (DH) when isoflurane is used as the principal anesthetic. When an intravenous anesthetic technique is used, DH can be produced by the administration of a peripheral vasodilator, eventually in association with low concentrations of isoflurane. The aim of this investigation was to compare the effects of these two different approaches on vital organ blood flow. DH was induced in 12 mongrel dogs with two different anesthetic techniques: inhaled anesthesia with isoflurane (ISO) or an intravenous anesthetic technique combining propofol and alfentanil in combination with the alpha-adrenoreceptor antagonist, urapidil, and isoflurane at low end-expiratory concentrations. Mean arterial pressure (MAP) was initially decreased by 20% of its baseline and then to 50 mm Hg. Vital organ blood flows and the cerebral metabolic rate for oxygen were determined at each decrement in MAP, and after discontinuation of DH. A decrease in cardiac output was observed in the ISO group when MAP was decreased to 50 mm Hg. Cerebral blood flow was constantly and significantly higher in the ISO group. The cerebral metabolic rate for oxygen did not change compared to baseline values in both groups. At a MAP of 50 mm Hg, a decrease in renal blood flow was observed in both groups. Splanchnic blood flow remained stable in the intravenous anesthetic group in contrast to the ISO group where splanchnic blood flow decreased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1993

Embolization of arteriovenous malformations of the brain: preliminary experience.

Transcatheter embolization was performed in 8 young patients (mean age 24.5 years) with intracerebral arteriovenous malformations. In total 12 arteries were embolized in 10 sessions. Clinical complaints of the patients included epilepsy in 4, sudden coma in 3 and severe sudden neurological deficit in 1. Intracerebral hemorrhage was documented in 4 patients and subarachnoid hemorrhage in 1. In all patients, prior to embolization a superselective Wada-test was performed under wake-up anesthesia. Embolization was performed with a mixture of acrylic glue and lipiodol. In one patient a detachable balloon was added. In 6 patients embolization of all the feeding arteries was possible, with total obliteration of the arteriovenous malformations in 4 and subtotal embolization (> 90%) in 2. In 2 patients reduction of the size of the arteriovenous malformation by one third was followed by total surgical removal of the lesion. In 1 patient reflux of the embolization material in the anterior choroidal artery caused severe neurological deficit with good clinical recuperation.

Adolescent↗
PubMed1992

Pulmonary embolism confirmed by transoesophageal echocardiography.

A 60-year-old patient suffered a pulmonary embolism following the application of an Esmarch and pneumatic tourniquet before arthroscopy of the knee. The diagnosis was suspected because of sudden hypotension, ECG changes, a decrease in end-expiratory carbon dioxide concentration and oxygen desaturation as indicated by pulse oximetry. Before performing a sternotomy and cardiopulmonary bypass for removal of pulmonary artery clots, the diagnosis was confirmed by the demonstration of severe right ventricular strain using transoesophageal echocardiography.

Arthroscopy↗
PubMed1992

Light anaesthesia with propofol for paediatric MRI.

Anaesthetic techniques and monitoring equipment may interfere with the technical demands of magnetic resonance imaging. The purpose of this study was to evaluate the safety and efficacy of a light anaesthetic technique with intravenous propofol in nonintubated children. In 20 neuropaediatric patients sedation was induced with propofol 1 mg.kg-1, followed by a continuous infusion titrated to produce adequate immobilisation. Oxygen, 4 l.min-1, was administrated by paediatric face mask. Respiratory rate, end-tidal carbon dioxide tension and oxygen saturation were continuously monitored. In 10 patients capillary blood gas tensions were determined 3 and 20 min after the procedure. Data are reported as mean (SD) and the mean (SD) total propofol dose was 5 (2) mg.kg-1.h-1. Oxygen saturation remained constantly higher than 96% in all patients. End-tidal carbon dioxide tension varied between 35 (7) mmHg 3 min after induction, and 41 (6) mmHg 30 min after the start of the procedure. End-tidal to capillary PCO2 difference was 4 (3) mmHg. Within 20 min after the end of the procedure all patients were fit for dismissal to the ward. One imaging sequence out of 49 was repeated because of movement artefacts. In conclusion, intravenous propofol sedation appears to be a safe and reliable technique for paediatric sedation during magnetic resonance imaging.

Anesthesia, Intravenous↗
PubMed1992

Influence of hydroxyethyl starch on coagulation in patients during the perioperative period.

The perioperative use of hydroxyethyl starch (HES) has been implicated as a possible cause of intracranial bleeding. The purpose of this study was to compare the influence on blood coagulation of the isovolemic replacement of 1-L blood loss with either 6% HES (molecular weight [MW] average: 450,000) or 5% human albumin during neurosurgery or lower abdominal surgery. Twenty patients scheduled for brain tumor surgery and 20 patients undergoing transabdominal hysterectomy were studied. The activated partial thromboplastin time, prothrombin time, fibrinogen concentration, factor VIII coagulant, von Willebrand factor antigen, platelet count, and the activated clotting time were compared after induction of anesthesia, after administration of 500 and 1000 mL of colloid solution, and 24 and 48 h postoperatively. All measured coagulation variables remained within physiologic range. Changes in coagulation indices were identical in neurosurgical and hysterectomy patients, except for a larger increase in fibrinogen concentration 24 and 48 h after hysterectomy. The acute phase reaction of factor VIII coagulant and von Willebrand factor, which plays a role in postoperative hypercoagulability, was attenuated by the use of HES. We conclude that isovolemic replacement of 1-L blood loss with either 6% HES (MW average: 450,000) or 5% human albumin does not interfere with normal hemostasis during and after neurosurgery or lower abdominal surgery.

Adult↗
PubMed1991

Use of desflurane for outpatient anesthesia. A comparison with propofol and nitrous oxide.

Desflurane's induction and recovery characteristics were compared to those of propofol-nitrous oxide in outpatients undergoing laparoscopic procedures. Ninety-two healthy patients were randomized to receive either: 1) propofol induction and propofol-nitrous oxide maintenance (control), 2) propofol induction and desflurane-nitrous oxide maintenance, 3) desflurane-nitrous oxide, or 4) desflurane alone for induction and maintenance of anesthesia. Inhalation induction with desflurane-nitrous oxide was faster than with desflurane alone (100 +/- 35 vs. 124 +/- 43 s). Inhalation inductions were associated with a high incidence of apnea (17 and 26%), breath-holding (26 and 39%), and coughing (30 and 22%) in groups 3 and 4, respectively. The emergence time after discontinuation of desflurane in oxygen (4.5 +/- 2.1 min.) was significantly less than that after propofol-nitrous oxide (7.3 +/- 3.9 min.). However, times from arrival in the recovery room until the patients were judged fit for discharge were similar for all four treatment groups. Digit-symbol substitution test results and sedation visual analogue scores also were similar during the first 2 h in the recovery room. A lower incidence of moderate-to-severe nausea was reported in group 1 (15% vs. 52, 52, and 59% in groups 2, 3, and 4, respectively). In conclusion, induction of anesthesia with desflurane was rapid but is associated with a high incidence of airway irritation. Emergence and recovery profiles after maintenance of anesthesia with desflurane compared favorably to a propofol-nitrous oxide combination. However, propofol was associated with a lower incidence of nausea than was desflurane after outpatient anesthesia for laparoscopic surgery.

Adult↗
PubMed1991

Efficacy of esmolol versus alfentanil as a supplement to propofol-nitrous oxide anesthesia.

In 97 outpatients undergoing ambulatory arthroscopic procedures, we compared esmolol with alfentanil when used to supplement propofol-N2O-atracurium anesthesia according to a randomized, double-blind protocol. After an initial intravenous dose of 16 micrograms/kg alfentanil, or 2 mg/kg of esmolol, a variable-rate infusion of alfentanil or esmolol was administered to maintain a stable heart rate. After induction of anesthesia with 2.5 mg/kg of propofol, mean arterial pressure decreased to a larger extent in the alfentanil-treated patients. Although heart rate and mean arterial pressure increased in both groups after tracheal intubation, alfentanil more effectively blunted the hemodynamic response to this stimulus. Maintenance of anesthesia was adequate in both treatment groups. After discontinuation of anesthesia, patients in the esmolol group opened their eyes earlier (7.2 +/- 2.4 min vs 9.8 +/- 4.6 min) than those in the alfentanil group. Esmolol-treated patients also reported less sedation in the first 15 min of recovery than those receiving alfentanil. However, there were no differences in times to ambulation and discharge between the groups. Esmolol-treated patients reported more postoperative pain for the first 15 min of recovery and more esmolol-treated patients required postoperative opioid analgesia than those treated with alfentanil. There were no significant differences in the incidences of nausea and vomiting between the two groups. The authors conclude that esmolol may be used in place of alfentanil to supplement propofol-N2O-atracurium anesthesia in outpatients undergoing arthroscopic procedures. However, hemodynamic responses to tracheal intubation were larger with esmolol, and avoidance of alfentanil did not decrease the incidence of postoperative nausea and vomiting in this outpatient population.

Adjuvants, Anesthesia↗
PubMed1991

Influence of anesthesia on cerebral blood flow and cerebral metabolism: an overview.

Knowledge of the influence of anesthetics on cerebral blood flow and metabolism is the key to both safe neuroanesthesia practice and understanding the possible neuroprotection offered by these agents. In this paper the authors summarize recent data from the literature. All volatile anesthetics (except for nitrous oxide) produce a dose dependent decrease in cerebral metabolism. The changes in cerebral blood flow depend on the changes in cerebral metabolism and on direct vasodilatory effects; frequently volatile anesthetics increase cerebral blood flow. Cerebral autoregulation is dose-dependently altered. While CO2-response is preserved in the normal brain, this is not necessarily the case in injured brain or in presence of brain edema or tumor. Therefore, the volatile anesthetics are probably not the best choice when brain perfusion is impaired. Intravenous anesthetics (except ketamine) cause a dose-dependent decrease in cerebral metabolism and blood flow. Propofol has identical effects as the other intravenous agents. Autoregulation is preserved during the administration of propofol. The effects of narcotic agents depend largely on the background anesthetic. Pathological conditions induced physiologic changes, and coadministration of other drugs can greatly alter the effects of anesthetics on the brain.

Anesthetics↗
PubMed1991

Effects of local anesthesia on recovery after outpatient arthroscopy.

The effects of intraarticular bupivacaine administration on postoperative pain and mobilization were evaluated in 97 healthy outpatients undergoing knee arthroscopy under general anesthesia. After completion of the operation, which was performed using a standardized general anesthetic technique, the patient's knee was injected with 30 mL of either 0.5% bupivacaine or saline solution (control), according to a randomized, double-blind protocol. Although there were no statistically significant differences in the patient's assessment of postoperative pain, patients receiving bupivacaine required significantly less opioid analgesic medication in the postoperative period. More importantly, ambulation occurred more rapidly in those patients treated with bupivacaine (versus saline solution), permitting them to be discharged earlier than the control patients (145 +/- 51 min vs 173 +/- 50 min). No adverse effects were noted after the 150-mg intraarticular dose of bupivacaine. On the day after operation, no differences in physical activity or analgesic requirements were detected between the two treatment groups. In conclusion, bupivacaine reduced the opioid requirements and facilitated earlier mobilization after knee arthroscopy without altering the patients' perception of postoperative pain.

Adult↗