Biomedical subjects

C J Kalkman

Publications and source records attributed to C J Kalkman.

At least 19 recordsLinked to original sources

PubMed1997

Efficacy of transcranial motor-evoked myogenic potentials to detect spinal cord ischemia during operations for thoracoabdominal aneurysms.

OBJECTIVE: Motor-evoked myogenic potentials after transcranial electrical stimulation monitor the vulnerable motoneuronal system of the spinal cord. This study reports our initial experiences with motor-evoked potentials to assess the adequacy of spinal cord perfusion during operations for thoracoabdominal aneurysms. METHODS: In 20 patients undergoing thoracoabdominal aneurysm operations, myogenic motor-evoked potentials were recorded. In 18 patients retrograde aortic perfusion was used. When spinal cord ischemia was detected, distal flow or mean arterial pressure was increased in an attempt to restore cord perfusion. By means of sequential crossclamping, motor-evoked potentials were also used to identify intercostal or lumbar arteries that needed to be reimplanted. RESULTS: Reproducible motor-evoked potentials could be recorded in all patients. During retrograde perfusion, nine patients showed a rapid decrease in the amplitude of motor-evoked potentials to less than 25% of baseline, indicating spinal cord ischemia. In five patients ischemic changes in motor-evoked potentials could be reversed by increasing distal and proximal blood pressures. In four patients ischemic changes during crossclamping necessitated segmental artery reimplantation. In three of these four patients intercostal or lumbar arteries were reattached. In one patient reimplantation of segmental arteries was not possible; this patient awoke paraplegic. Segmental arteries were ligated after confirmation of intact motor-evoked potentials during aortic clamping in eight patients. None of these patients had a neurologic deficit. The absence of motor-evoked potentials at the end of the procedure always indicated a postoperative motor deficit. CONCLUSION: During operations for thoracoabdominal aneurysms, monitoring of motor-evoked potentials is an effective technique to detect spinal cord ischemia within minutes. This modality can be used to guide the management of distal aortic perfusion techniques and may also help to identify segmental arteries that need to be reattached.

Adult↗

PubMed1996

Myogenic motor-evoked potential monitoring using partial neuromuscular blockade in surgery of the spine.

STUDY DESIGN: The authors analyzed motor-evoked potentials using transcranial electrical cortical stimulation during spinal surgery in 40 patients under conditions of partial neuromuscular blockade. OBJECTIVES: The results were used to investigate the utility of motor-evoked potential monitoring to prevent neurologic injury in spinal surgery. SUMMARY OF BACKGROUND DATA: Noninvasive transcranial electrical motor-evoked potentials are reportedly effective in predicting postoperative spinal cord deficits caused by intraoperative occurrences. However, the sensitivity and specificity of these predictions have not been assessed under conditions of partial neuromuscular blockade during a wide variety of surgical procedures. METHODS: Compound muscle action potentials were recorded at the tibialis anterior muscle while general anesthesia was maintained with nitrous oxide, etomidate, and sufentanil. Surgery was performed at all spinal levels for a variety of diagnoses. RESULTS: Reference motor-evoked potential amplitudes, measured after induction of partial neuromuscular blockade, ranged from 25 to 7562 microV (median, 600 microV). Variation in intraoperative motor-evoked potential amplitude ranged from signal loss to a 3440% increase. A decrease to less than 20% of the individual reference value for motor-evoked potential amplitude occurred at least once in nine patients (22.5%) but as not associated with postoperative motor deficits. Two patients who had loss of motor-evoked potential signal without recovery did have postoperative motor deficits. Motor-evoked potentials predicted postoperative motor improvement in six patients. An improvement threshold of 160% of the reference amplitude predicted postoperative motor improvement with 100% sensitivity and 81% specificity. CONCLUSIONS: The authors support the utility of recording transcranial electrical motor-evoked potentials in spinal surgery under partial neuromuscular blockade. Recovery of lost motor-evoked potentials was not associated with postoperative motor deficits, whereas non-recovery of lost motor-evoked potentials was.

Adolescent↗

PubMed1996

Influence of motivation of care providers on the incidence of postoperative hypoxaemia in the recovery room.

We have studied the influence of motivation of care providers on the incidence and duration of postoperative hypoxaemia in the recovery room. In a prospective, switch-back designed cohort study, we have compared the incidence of low pulse oximeter saturation values (SpO2) during pre-intervention, intervention and post-intervention phases. Low SpO2 values were classified as either hypoxaemia (SpO2 < or = 90%, minimum duration 1 min) or artefact. Pulse oximetry trend data from 1350 patients, 450 in each group, were analysed. During the intervention phase, motivation was increased by adding an explicit instruction to prevent and treat low SpO2 values and making personnel aware that they were being studied (Hawthorne effect). The incidence of hypoxaemia decreased significantly from 17.8% during the pre-intervention phase to 11.6% during the intervention phase (relative risk (RR) 0.65, 95% confidence interval (CI) 0.47-0.90; P < 0.01). The incidence of severe hypoxaemia (SpO2 < or = 85%, 1 min) decreased from 7.8% to 3.3% (RR 0.43, CI 0.24-0.76; P < 0.01). The number of patients who had severe hypoxaemia for more than 5 min decreased from 13 to 1 (RR 0.08, CI 0.02-0.36; P < 0.01). In the post-intervention period, the incidence of hypoxaemia returned to pre-intervention values. The results of this study suggest that motivation of care providers to prevent and treat low SpO2 is an important determinant of postoperative hypoxaemia in the recovery room.

Adolescent↗

PubMed1996

The use of a circumferential cathode improves amplitude of intraoperative electrical transcranial myogenic motor evoked responses.

Measurement of motor evoked responses to transcranial electrical stimulation (tc-MER) is a technique for intraoperative monitoring of motor pathways. Since most anesthetics significantly reduce motoneuronal excitability, optimal stimulation paradigms should be sought. We compared the efficiency of stimulus delivery using two different configurations of the cathode component of the stimulating electrode pair (circumferential: Fz, F3, F4, A1, and A2 versus a single cathode at Fz). The anode was positioned at Cz with both cathode configurations. Fourteen neurologically normal patients undergoing spinal surgery were anesthetized with sufentanil-N2O-ketamine. Partial neuromuscular blockade (single twitch height 25%) was maintained with vecuronium. Compound action potentials to transcranial stimulation with both cathode configurations were recorded from the tibialis anterior muscle. All recordings were completed before spinal manipulation. The median amplitude response using the Fz cathode configuration was 256 microV (10th-90th percentiles: 50-641 microV). With the circumferential cathode configuration, tc-MER amplitude increased to 281 (87-1479) microV (P < 0.01). There was no significant difference in onset latency between electrode configurations. The observed tc-MER amplitude augmentation with the use of a circumferential cathode might allow tc-MER monitoring in those patients who do not have sufficiently reproducible responses when a single cathode is used. A possible explanation is that the circumferential cathode alters the direction of the electrical currents in the cortex, resulting in more efficient depolarization of cortical motor neurons.

Action Potentials↗

PubMed1996

A comparison of the sensitivity of epidural and myogenic transcranial motor-evoked responses in the detection of acute spinal cord ischemia in the rabbit.

Monitoring motor-evoked responses to transcranial stimulation (tc-MERs) provides information about the functional status of the spinal cord during operations that pose the risk of spinal cord ischemia. Responses can be recorded from the epidural space (epidural tc-MERs) or from muscle (myogenic tc-MERs). In this study the relative sensitivity of epidural and myogenic tc-MERs to acute spinal cord ischemia was compared. Spinal cord ischemia was produced by infrarenal aortic balloon occlusion in nine anesthetized New Zealand White rabbits. Tc-MERs were evoked by transcranial electrical stimuli applied to the scalp. Responses were recorded from the lumbar epidural space and from the soleus muscle, and the effect of aortic occlusion was assessed. The peak-to-peak amplitude of the direct wave of the epidural response decreased gradually during aortic occlusion in eight animals and increased in one. The median (10th to 90th percentiles) time to a 50% reduction in amplitude was 11.3 (3-22) min. In contrast, myogenic responses disappeared within 2 min after the start of occlusion in all animals. Lower extremity ischemia as a cause of changes in myogenic tc-MER amplitude was excluded by ligating the right femoral artery and demonstrating that myogenic responses were preserved for 30 min, before occluding the aorta. We conclude that myogenic responses are more sensitive to acute spinal cord ischemia than epidural responses. The rapid detection of spinal cord ischemia with transcranial myogenic motor-evoked responses could be of clinical use in assessing the adequacy of spinal cord blood flow during operations where the spinal cord is at risk.

Acute Disease↗

PubMed1996

A comparison of the electrophysiologic characteristics of EEG burst-suppression as produced by isoflurane, thiopental, etomidate, and propofol.

Electroencephalogram (EEG) burst-suppression can be produced with several anesthetic agents. Discussions of burst-suppression suggest that it has been viewed by many as a relatively uniform physiologic state independent of the agent used to produce it. This view may be an oversimplification. In this study, relatively deep EEG burst-suppression (suppression to burst time ratio, 4:1) was induced in rats with isoflurane (I), thiopental (T), etomidate (E), and propofol (P). Burst duration, maximum peak-to-peak voltage, area under the curve, and the ratio of power in high versus low frequencies of EEG recorded in both cortex and subcortex (thalamus) were determined. Analysis of the bursts revealed significant differences in duration [I, 1.4 +/- 0.4 (SD); T, 0.8 +/- 0.5; E, 0.3 +/- 0.1; P, 0.4 +/- 0.1 seconds], peak-to-peak voltage (I, 488 +/- 146; T, 285 +/- 106; E, 310 +/- 87; P, 249 +/- 50 muV), and area under the curve (I, 111 +/- 24; T, 35 +/- 31; E, 17 +/- 7; P, 21 +/- 4 muV-s) for all agent pairs except etomidate and propofol. Suppression phase analysis revealed considerable residual activity with all four agents, although peak-to-peak voltage (I, 129 +/- 29; T, 64 +/- 20; E, 62 +/- 11; P, 40 +/- 15 muV) and area under the curve (I, 73 +/- 17; T, 37 +/- 14; E, 30 +/- 5; P, 22 +/- 10 muV-s) were greatest with isoflurane. The cortical versus subcortical comparison revealed, for all agents, greater peak-to-peak voltage and area under the curve in the subcortex. The data indicate that the electrophysiologic characteristics of burst-suppression vary among the four agents, with the possible exception of etomidate and propofol. The data suggest that the neurophysiologic states associated with burst-suppression produced by various anesthetics should not be assumed to be uniform.

Anesthetics, Inhalation↗

PubMed1996

Remote controlled prolonged conscious sedation for gynaecological radiotherapy.

Conscious sedation with subanaesthetic doses of propofol is an effective technique for the management of highly anxious patients in dentistry. Prolonged administration of propofol to achieve conscious sedation in spontaneously breathing patients without an airway adjunct has not been reported previously. We describe the management of target-controlled conscious sedation with propofol for 21 h in a patient undergoing gynaecological radiotherapy.

Anesthetics, Intravenous↗

PubMed1995

Laparoscopy without pneumoperitoneum. Effects of abdominal wall retraction versus carbon dioxide insufflation on hemodynamics and gas exchange in pigs.

Laparoscopic surgery with CO2 insufflation is associated with adverse effects on hemodynamics and gas exchange. The abdominal wall retractor (AWR) is an alternative for pneumoperitoneum. Hemodynamics and gas exchange during the use of an AWR were compared to those of CO2 pneumoperitoneum. In eight pigs subjected to 1 h of CO2 pneumoperitoneum or abdominal wall retraction, hemodynamics, gas exchange, and oxygen transport were studied in a randomized cross-over study design. The only change observed during abdominal wall retraction was mild respiratory alkalosis. In contrast, during CO2 pneumoperitoneum mean arterial blood pressure increased 13%, central filling pressures doubled, and a small increase in cardiac output was observed. Peak airway pressures increased 50%, end-tidal CO2 increased 20%, and respiratory acidosis was induced (arterial pH from 7.46 +/- 0.07 to 7.31 +/- 0.06 and pCO2 from 33 +/- 3 mmHg to 53 +/- 4 mmHg). Arterial PO2 decreased but mixed venous oxygen saturation and oxygen consumption were unaffected. In contrast with CO2 pneumoperitoneum, laparoscopy using abdominal wall retraction was not associated with adverse effects on hemodynamics or gas exchange.

Abdominal Muscles↗

PubMed1995

Hemodynamics during laparoscopy in the supine or prone position. An experimental study.

During laparoscopy elevations in arterial pressure and a decrease in cardiac output have been reported. Laparoscopic surgery performed in the prone position may be advantageous for some surgical procedures, but the hemodynamic effects of pneumoperitoneum in this position have not been studied. We studied the effects of different levels of increased intraabdominal pressure on hemodynamics and oxygen transport in eight pigs in the prone and the supine position. Increases in intraabdominal pressure did not result in decreased cardiac output or in a reduction of oxygen transport and consumption in either position. These results suggest that laparoscopy in the prone position does not result in more severe hemodynamic depression than laparoscopy in the supine position.

Analysis of Variance↗

PubMed1995

LabVIEW: a software system for data acquisition, data analysis, and instrument control.

Computer-based data acquisition systems play an important role in clinical monitoring and in the development of new monitoring tools. LabVIEW (National Instruments, Austin, TX) is a data acquisition and programming environment that allows flexible acquisition and processing of analog and digital data. The main feature that distinguishes LabVIEW from other data acquisition programs is its highly modular graphical programming language, "G," and a large library of mathematical and statistical functions. The advantage of graphical programming is that the code is flexible, reusable, and self-documenting. Subroutines can be saved in a library and reused without modification in other programs. This dramatically reduces development time and enables researchers to develop or modify their own programs. LabVIEW uses a large amount of processing power and computer memory, thus requiring a powerful computer. A large-screen monitor is desirable when developing larger applications. LabVIEW is excellently suited for testing new monitoring paradigms, analysis algorithms, or user interfaces. The typical LabVIEW user is the researcher who wants to develop a new monitoring technique, a set of new (derived) variables by integrating signals from several existing patient monitors, closed-loop control of a physiological variable, or a physiological simulator.

Analog-Digital Conversion↗

PubMed1995

Effects of pneumoperitoneum with helium on hemodynamics and oxygen transport: a comparison with carbon dioxide.

Pneumoperitoneum with CO2 is associated with adverse effects, such as hypercarbia, arrhythmias, and circulatory depression, which may limit its use in patients with underlying disease. Some of these effects may be caused by CO2 absorption resulting in acid-base disturbances. Laparoscopic insufflation with helium may be a good alternative for CO2, since it is chemically inert. Because there are few data on the use of helium for laparoscopy, we studied hemodynamics and gas exchange during insufflation with CO2 or helium in 8 pigs at 10, 15, and 20 mm Hg intraabdominal pressure. Heart rate did not change significantly with both gases. Arterial blood pressure increased with CO2 (p < 0.05) but not with helium. Cardiac output, mixed venous oxygen saturation, and oxygen consumption did not decrease, whereas central venous filling pressures increased during insufflation with either gas. Insufflation with CO2 resulted in mild increases in arterial, central venous, and end-expiratory CO2. The results suggest that pneumoperitoneum with helium will not be associated with profound circulatory depression or oxygen transport abnormalities. In addition, the use of helium is not associated with acid-base disturbances, although central venous filling pressures are similarly increased as with the use of CO2 pneumoperitoneum.

Acid-Base Imbalance↗

PubMed1995

Electroencephalographic characteristics of emergence from propofol/sufentanil total intravenous anesthesia.

We recorded the electroencephalogram (EEG) in 16 patients during propofol/sufentanil total intravenous anesthesia to determine whether EEG changes might predict imminent awakening during emergence. Changes in absolute and relative power in four frequency bands, median frequency (MF), 95th percentile frequency (F95), and two frequency band power ratios (beta/alpha and (alpha+beta)/delta) were quantified. One minute before eye opening, absolute power in the delta and alpha bands had decreased to 49% (25%-73%) and 42% (25%-58%) of the value during the infusion (P > 0.005). MF, F95, and the two frequency band power ratios increased during emergence (P > 0.05). Of the individual spectral variables, only a 50% decrease in absolute alpha power was more than 90% sensitive and specific in predicting eye opening. We conclude that, although pronounced EEG changes occur during emergence from propofol/sufentanil anesthesia, the EEG does not reliably predict eye opening.

Adult↗

PubMed1995

Improved amplitude of myogenic motor evoked responses after paired transcranial electrical stimulation during sufentanil/nitrous oxide anesthesia.

BACKGROUND: Measurement of motor evoked responses to transcranial stimulation (tc-MER) is a technique for intraoperative monitoring of motor pathways in the brain and spinal cord. However, clinical application of tc-MER monitoring is hampered because most anesthetic techniques severely depress the amplitude of motor evoked responses. Because paired electrical stimuli increase tc-MER responses in awake subjects, we examined their effects in anesthetized patients undergoing surgery. METHODS. Eleven patients whose neurologic condition was normal and who were undergoing spinal or aortic surgery were anesthetized with sufentanil-N20-ketamine. Partial neuromuscular blockade (single-twitch height 25% of baseline) was maintained with vecuronium. Single and paired electrical stimuli were delivered to the scalp, and compound action potentials were recorded from the tibialis anterior muscle. The amplitude and latency of the tc-MERs were measured as the interval between paired stimuli was varied between 0 (single stimulus) and 10 ms. All recordings were completed before spinal manipulation or aortic clamping. RESULTS: Median amplitude of the tc-MER after a single stimulus was 106 microV (10th-90th percentiles: 23-1,042 microV), and the latency to onset was 33.2 +/- 1.4 ms (SD). With paired stimuli (interstimulus interval 2-3 ms), tc-MER amplitudes increased to 285 (79-1,605) microV, or 269% of the single-pulse response (P < 0.01). Reproducibility of individual responses increased with paired stimulation. Onset latency decreased to 31.4 +/- 3.2 ms (P < 0.05). Maximum amplitude augmentation was observed with interstimulus intervals between 2 and 5 ms and in patients with low-amplitude responses after single-pulse stimulation. CONCLUSIONS: Application of paired transcranial electrical stimuli increases amplitudes and reproducibility of tc-MERs during anesthetic-induced depression of the motor system. The effect may represent temporal summation of stimulation at cortical or spinal sites. The results of this study warrant further clinical evaluation of paired transcranial stimulation.

Action Potentials↗

PubMed1994

Neurologic injury after insertion of laminar hooks during Cotrel-Dubousset instrumentation.

BACKGROUND DATA: Although the use of Cotrel-Dubousset (CD) instrumentation has improved results of operative treatment of scoliotic deformities, this technique may be associated with increased risk of neurologic injury. CASE HISTORIES: Two cases of neurologic complications immediately after insertion of lumbar laminar hooks during CD instrumentation for correction of scoliosis are reported. METHODS: Between 1986 and 1992, the authors performed 220 CD instrumentations for various spinal deformities. All patients were monitored with posterior tibial nerve somatosensory cortical evoked potentials (PTN-SSEPs). CONCLUSION: These cases demonstrate that caution should be exercised during introduction of laminar hooks on the concave side during CD instrumentation for scoliotic deformities. Continuous neurophysiologic monitoring of spinal cord conduction may aid in early detection of local compression at the spinal cord or cauda equina level.

Adolescent↗

PubMed1994

Intraperitoneal local anaesthetics after laparoscopic cholecystectomy: effects on postoperative pain, metabolic responses and lung function.

We have compared the efficacy of 0.9% NaCl 20 ml (n = 15), 0.25% bupivacaine 20 ml (n = 15) and 0.5% lignocaine 20 ml (n = 15), administered i.p., in reducing postoperative pain and opioid requirements, and modifying the metabolic response to surgery and postoperative lung function after laparoscopic cholecystectomy. There were no differences in postoperative pain scores (visual analogue scale and verbal rating scale) between the three groups in the first 4 h after operation and in analgesic requirements during the first 24 h. In all groups, forced vital capacity, peak expiratory flow and forced expiratory volume in 1 s decreased 2 h after surgery (P < 0.001). Ventilatory values recovered only partially in the first 2 days after operation (P < 0.05), with no significant differences between groups. Plasma concentrations of glucose and cortisol increased after surgery (P < 0.05). Cortisol concentrations returned to baseline 48 h after operation. There were no significant differences between the groups in any measured variable. These data suggest that the administration of 20 ml of local anaesthetics i.p. is not effective in reducing postoperative pain, improving lung function, or attenuating the metabolic endocrine response after laparoscopic cholecystectomy.

Adult↗

PubMed1994

Effects of droperidol, pentobarbital, and ketamine on myogenic transcranial magnetic motor-evoked responses in humans.

Myogenic motor-evoked responses to transcranial magnetic stimulation of the motor cortex (tcmag-MERs) may become clinically useful for the noninvasive assessment of motor pathway conduction during surgery. However, application is hindered because most anesthetic regimens result in severe depression of tcmag-MER amplitudes. As part of our systematic attempts to identify anesthetic agents and supplements suitable for use during tcmag-MER recording, we studied the effect of bolus doses of pentobarbital (1.5 mg/kg), droperidol (0.07 mg/kg), or ketamine (1 mg/kg), administered intravenously, on compound muscle action potentials to transcranial magnetic stimulation in five healthy volunteers. The doses were chosen to be comparable with doses that might be suitable for supplementation of a nitrous oxide/opioid anesthetic technique. Droperidol administration resulted in sustained amplitude depression of both tibialis and adductor pollicis tc-MERs to 30 +/- 9% and 39 +/- 14% of baseline (P < 0.01). Tcmag-MER amplitude changes after pentobarbital were variable, ranging from no change to substantial amplitude depression (to 20% of baseline) in two subjects. In contrast, ketamine administration did not result in significant amplitude depression. In three subjects, tibialis anterior amplitude increased to 150 to 220% of control values in the first 10 minutes after ketamine. Onset latency was unchanged after any drug. These data indicate that tcmag-MERs are moderately depressed after droperidol and pentobarbital but well preserved after ketamine. Ketamine may be a more suitable supplement to opioid/nitrous oxide anesthesia than droperidol or pentobarbital.

Adult↗

PubMed1994

Haemodynamic effects of pneumoperitoneum for laparoscopic surgery: a comparison of CO2 with N2O insufflation.

We studied the haemodynamic effects of intra-abdominal insufflation with either CO2 (n = 15) or N2O (n = 15) in patients undergoing laparoscopic surgery. Haemodynamic variables were measured at increasing levels of intra-abdominal pressure up to 20 mmHg. In the CO2 group cardiac index decreased from 2.6 +/- 0.6 to 2.0 +/- 0.4 litre min-1 m-2 (mean +/- SD, P < 0.001) and in the N2O group from 2.6 +/- 0.5 to 1.8 +/- 0.4 litre min-1 m-2 (P < 0.001)). In the CO2 group, this was accompanied by increases in mean arterial pressure, systemic vascular resistance index and central venous pressure without change in heart rate. In contrast, during N2O insufflation mean arterial pressure decreased (from 77 +/- 8 to 63 +/- 15 mmHg (P < 0.001)) without change in vascular resistance. No further changes in haemodynamic variables were observed during head-up tilt in both groups. After desufflation mean arterial pressure increased in the N2O group to pre-insufflation levels and cardiac index increased in both groups (P < 0.001), but reached pre-insufflation levels only in the CO2 group. In both groups central venous O2 tension and saturation decreased at maximum intra-abdominal pressure and increased after release of the pneumoperitoneum. The results indicate that laparoscopic insufflation with either CO2 or N2O results in cardiovascular depression. Insufflation with N2O may decrease blood pressure, whereas mean arterial pressure is better preserved with CO2 insufflation.

Adult↗

PubMed1993

Effect of ibuprofen on regional eicosanoid production and neuronal injury after forebrain ischemia in rats.

Post-ischemic metabolism of arachidonic acid by cyclooxygenase results in the elaboration of numerous eicosanoids and in the generation of free radicals. Accordingly, the effect of cyclooxygenase inhibition by ibuprofen on post-ischemic eicosanoid production and delayed neuronal death was evaluated in Wistar-Kyoto rats subjected to incomplete forebrain ischemia. In control (C) and ibuprofen-treated groups (n = 5 each), pre- and post-ischemic eicosanoid production in the caudate nucleus (CN) and dorsal hippocampus (HPC) were evaluated by microdialysis. The ibuprofen-treated animals were given ibuprofen, 15 mg/kg i.v., prior to insertion of microdialysis probes. Forebrain ischemia was induced by bilateral carotid artery occlusion (BCAO) for 10 min with simultaneous hypotension to 35 Torr. The concentrations of thromboxane B2 (TxB2), 6-keto-PGF1 alpha and PGF2 alpha in the microdialysate were measured by radioimmunoassay. In two additional concurrent groups of rats (n = 10 each), neuronal injury in the HPC, CN and cortex (parietal, temporal and entorhinal regions) was evaluated histologically three days after 10 min of forebrain ischemia with and without pre-ischemic ibuprofen administration. In the control microdialysis group, levels of TxB2, 6-keto-PGF1 alpha and PGF2 alpha increased in both CN and HPC after probe insertion. These probe related increases were substantially reduced in the ibuprofen group. After ischemia and reperfusion in the control group, the levels of TxB2 and PGF2 alpha increased in both CN and HPC. Levels of 6-keto-PGF1 alpha increased in the CN but not in the HPC. The administration of ibuprofen substantially reduced post-ischemic TxB2 and PGF2 alpha levels in both CN and HPC and decreased 6-keto-PGF1 alpha levels in the CN. The results of these initial microdialysis studies left the possibility that, in the ibuprofen group, the reduction in eicosanoid levels after probe penetration might have influenced the subsequent post-ischemic eicosanoid production. Therefore, in an additional group of animals (n = 5), ibuprofen was administered after probe insertion. Only PGF2 alpha levels were measured in this group. Increased levels of PGF2 alpha comparable to the original control group were detected after probe penetration. Nonetheless, after ibuprofen administration, the pre- and post-ischemic levels of PGF2 alpha were again significantly reduced. In the histologic evaluation groups, overall neuronal injury was significantly less in the ibuprofen treated animals. This protective effect of ibuprofen was most clearly evident in the CA3 sector of the HPC.(ABSTRACT TRUNCATED AT 400 WORDS)

6-Ketoprostaglandin F1 alpha↗