bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cerebral Histopathology following Portal Venous Infusion of Bacteria in a Chronic Porcine Model
Authors: Bogdanski Ralph , Blobner Manfred , Becker Ingrid , Hänel Frank , Fink Heidrun , Kochs Eberhard 
Published: November 2003

Background
The aim of this study was to histologically investigate brain damage after prolonged periods of bacteremia in pigs.

Methods
Twenty-one pathogen-free Göttingen minipigs were anesthetized and instrumented with a femoral arterial, a pulmonary arterial, and through midline abdominal incision with a portal venous catheter. After craniotomy the superior sagittal sinus was cannulated. A lumbosacral spinal catheter was inserted for sampling of cerebrospinal fluid. Twelve hours after instrumentation, the animals were randomized in two groups: septic and control animals. The septic group received an infusion of 107 colony-forming units per kilogram of living Escherichia coli over 0.5 h through portal venous catheter each day. The control group received saline. Postoperative intensive care treatment included 4 days of controlled mechanical ventilation, sedation, and intravenous nutrition. The brains then were removed, fixed, and processed for histology. Each pathologic alteration found in the samples was assessed and given a severity code (0-3).

Results
Sham-operated animals showed no alterations caused by the instrumentation and the intensive care treatment. The septic group showed typical clinical signs of sepsis. Vasopressor support and mechanical ventilation prevented systemic hypotension and hypoxemia. High serum and cerebrospinal fluid levels of interleukin-6 and tumor necrosis factor-alpha were detected. The septic group showed severe histologic abnormalities of the brain including perivascular edema, spongiform degeneration, hyperemia, and purpura. Damage of neurons was seen including eosinophilic cytoplasm, shrunken nuclei, and disintegration of the nuclear membrane.

Conclusions
Abdominal sepsis induced severe brain damage that was not related to systemic hypoxia or ischemia. High cerebrospinal fluid levels of tumor necrosis factor-alpha and interleukin-6 were related to an inflammatory process in the brain resulting in cerebral edema and death of neurons.
Differential Effects of Halothane and Thiopental on Surfactant Protein C Messenger RNA In Vivo and In Vitro in Rats
Authors: Paugam-Burtz Catherine , Molliex Serge , Lardeux Bernard , Rolland Corinne , Aubier Michel , Desmonts Jean-Marie , Crestani Bruno 
Published: November 2003

Background
Pulmonary surfactant is a complex mixture of proteins and phospholipids synthetized by alveolar type II cells. Volatile anesthetics have been shown to reduce surfactant phospholipid biosynthesis by rat alveolar type II cells. Surfactant-associated protein C (SP-C) is critical for the alveolar surfactant functions. Our goal was to evaluate the effects of halothane and thiopental on SP-C messenger RNA (mRNA) expression in vitro in rat alveolar type II cells and in vivo in mechanically ventilated rats.

Methods
In vitro, freshly isolated alveolar type II cells were exposed to halothane during 4 h (1, 2, 4%) and 8 h (1%), and to thiopental during 4 h (10, 100 micrometer) and 8 h (100 micrometer). In vivo, rats were anesthetized with intraperitoneal thiopental or inhaled 1% halothane and mechanically ventilated for 4 or 8 h. SP-C mRNA expression was evaluated by ribonuclease protection assay.

Results
In vitro, 4-h exposure of alveolar type II cells to thiopental 10 and 100 micrometer increased their SP-C mRNA content to 145 and 197%, respectively, of the control values. In alveolar type II cells exposed for 4 h to halothane 1, 2, and 4%, the SP-C mRNA content increased dose-dependently to 160, 235, and 275%, respectively, of the control values. In vivo, in mechanically ventilated rats, 4 h of halothane anesthesia decreased the lung SP-C mRNA content to 53% of the value obtained in control (nonanesthetized, nonventilated) animals; thiopental anesthesia increased to 150% the lung SP-C mRNA content.

Conclusions
These findings indicate that halothane and thiopental used at clinically relevant concentrations modulate the pulmonary SP-C mRNA content in rats. In vivo, the additive role of mechanical ventilation is suggested.
Stereospecific Interaction of Ketamine with Nicotinic Acetylcholine Receptors in Human Sympathetic Ganglion-like SH-SY5Y Cells
Authors: Friederich Patrick , Dybek André , Urban Bernd W. 
Published: November 2003

Background
Surprising clinical evidence suggests a block of sympathetic transmission by ketamine. The action of ketamine on nicotinic acetylcholine receptors (nAChRs) in human ganglions is unknown. Because ganglionic transmission depends on nAChRs, such information may help to clarify whether ketamine impairs ganglionic transmission in men. Because racemic ketamine as well as S(+)-ketamine are used clinically, the authors investigated stereospecific effects on human ganglionic nAChRs. Stereospecific psychomimetic effects have been attributed to voltage-dependent Kv channel inhibition; therefore the effects on nAChRs were compared with those on Kv channels present in the same cells.

Methods
Whole-cell currents through nAChRs and K channels were measured in SH-SY5Y cells with the patch-clamp technique by application of acetylcholine (1 mm, nAChRs) or by a step depolarization from a holding potential of -80 mV to +40 mV (K channels). Electrolyte conditions were identical for both currents.

Results
Racemic ketamine and the isomers inhibited nAChRs and K channels in a concentration-dependent and reversible manner. Racemic ketamine inhibited nAChRs and K channels, with the anesthetic concentration inducing the half-maximal effect being 1.4 and 300 micrometer, respectively. Only inhibition of the nAChRs was stereoselective. The half-maximal concentrations were 0.8 and 3.6 micrometer for S(+)- and R(-)-ketamine. The K channels were 350 and 70 times less sensitive to the effects of S(+)- and R(-)-ketamine.

Conclusion
Ketamine at concentrations found during clinical anesthesia exerts stereospecific effects on human ganglionic nAChRs but not on voltage-dependent K channels. Our results support the view that ketamine impairs sympathetic ganglionic transmission. Nonspecific effects on voltage-dependent K channels may underlie psychomimetic side effects.
Thoracic Epidural Anesthesia Increases Mucosal Perfusion in Ileum of Rats
Authors: Sielenkämper Andreas W. , Eicker Kolja , Van Aken Hugo 
Published: November 2003

Background
Previous studies reported that thoracic epidural anesthesia (TEA) protected against a decrease in gastric intramucosal pH, suggesting that TEA increased gut mucosal perfusion. The current study examines the effects of TEA on ileal mucosa using intravital microscopy in anesthetized rats.

Methods
Nineteen rats were equipped with epidural catheters, with the tip placed at T7 through T9. Rats were anesthetized and mechanically ventilated. After midline abdominal incision, the ileum was prepared for intravital microscopy. Videomicroscopy on the ileal mucosa was performed before and after epidural infusion of 20 microliter of bupivacaine 0.4% (TEA group, n = 11 rats) or normal saline (control group, n = 8 rats). Microvascular blood flow in ileum mucosa was assessed offline using computerized image analysis.

Results
Control rats exhibited unchanged mean arterial pressure and microvascular perfusion. During TEA, mean arterial pressure was decreased compared with the control group (93 +/- 10 vs. 105 +/- 9 mmHg; P < 0.05). Epidural bupivacaine increased red cell velocity in terminal arterioles from 888 +/- 202 to 1,215 +/- 268 micrometer/s (control, 793 +/- 250 to 741 +/- 195 micrometer/s; P < 0.001 between groups). Because arteriolar diameter was not affected, this increase in red cell velocity may represent an increase in arteriolar blood flow. Total intercapillary area (inversely related to perfused capillary density) was unchanged, but for the TEA group the difference between total intercapillary area and the intercapillary area calculated for continuously perfused capillaries was decreased compared with the control group (16 +/- 12 vs. 40 +/- 19%; P < 0.001), indicating a decrease in intermittent (stop-and-go) blood flow in the villus microcirculation.

Conclusion
Thoracic epidural anesthesia increased gut mucosal blood flow and reduced intermittent flow in the villus microcirculation in the presence of a decreased perfusion pressure.
Financial Impact If Payers Use Medicare Rates
Authors: Johnstone Robert E. , Hosaflook Carrie 
Published: November 2003

Background
In 1992, Medicare changed its method for calculating physician payments. The resulting fee schedules have contained low payments for anesthesiologists. Now, other third-party (insurance) payers are using these schedules. The financial impact on anesthesiologists if all payers pay Medicare rates is unknown.

Methods
Payments from Medicare were compared with payments from other third parties in each clinical procedural terminology (CPT) grouping used by the West Virginia University Department of Anesthesiology during 1998. Changes in total Department of Anesthesiology receipts were determined if non-Medicare third-party payers paid Medicare rates. Then, the effect of adding payments at Medicare rates from patients without insurance was determined. Finally, potential changes in receipts of the Departments of Anesthesiology, Radiology, Surgery, and Medicine were compared by considering only patients with insurance and recalculating total payments to the departments using Medicare rates.

Results
Medicare paid less than other third-party payers in every clinical procedural terminology group. Total Department of Anesthesiology payments would decrease by 31% if all non-Medicare third-parties paid Medicare rates. Adding payments at Medicare rates from patients without insurance still leads to a 21% decrease in total Department of Anesthesiology receipts. Considering only patients with third-party coverage, Medicare-rate payments would decrease total Department of Anesthesiology payments by 37%, whereas radiology, surgery, and medicine payments would decrease by 26, 22, and 13% respectively.

Conclusions
Universal payments at Medicare rates would substantially reduce revenue to anesthesiologists, proportionally more than to radiologists, surgeons, or internists.
Substance P (Neurokinin-1) Antagonist Prevents Postoperative Vomiting after Abdominal Hysterectomy Procedures
Authors: Gesztesi Zsuzsanna , Scuderi Phillip E. , White Paul F. , Wright William , Wender Ronald H. , D’Angelo Robert , Black L. Suzanna , Dalby Patricia L. , MacLean David 
Published: November 2003

Background
The safety and antiemetic efficacy of CP-122,721, a novel neurokinin-1 antagonist, was evaluated when administered alone or in combination with ondansetron.

Methods
Using a randomized, double-blind, placebo-controlled study design, CP-122,721 was initially compared with placebo and subsequently to ondansetron alone and in combination for prophylaxis against postoperative nausea and vomiting in 243 women undergoing abdominal hysterectomy. In the dose-ranging studies (n = 86), patients received either CP-122,721 100 mg (vs. placebo) or 200 mg (vs. placebo) orally 60-90 min before induction of anesthesia. In the interaction study (n = 157), patients received CP-122,721 200 mg or placebo 60-90 min before induction of anesthesia, and ondansetron 4 mg or saline 2 ml intravenously 15-30 min before the end of surgery. Patients assessed their level of nausea and pain on arrival in the postanesthesia care unit and at 0.5-, 1-, 1.5-, 2-, 4-, 8-, 12-, and 24-h intervals postoperatively. Emetic episodes, need for rescue antiemetic-antinausea medication, postoperative complications, and patient satisfaction were recorded.

Results
In the initial dose-ranging study, only 10% of the patients experienced emesis within the first 8 h after surgery with CP-122,721 200 mg compared with 50% in the placebo group. CP-122,721 200 mg also decreased the need for rescue medication (25% vs. 48%). CP-122,721 100 mg was less effective than 200 mg in decreasing the incidence of repeated episodes of emesis. In the interaction study, 6% of the patients receiving CP-122,721 200 mg orally experienced emesis less than 2 h after surgery compared with 17% with ondansetron alone. With combined therapy, only 2% experienced emesis. In addition, the median times for 75% of patients to remain free from postoperative nausea and vomiting were 82, 75, and 362 min in the ondansetron, CP-122,721, and combination groups, respectively.

Conclusions
Oral CP-122,721 200 mg decreased emetic episodes compared with ondansetron (4 mg intravenously) during the first 24 h after gynecologic surgery; however, there was no difference in patient satisfaction.
Lower Extremity Neuropathies Associated with Lithotomy Positions
Authors: Warner Mark A. , Warner David O. , Harper C. Michel , Schroeder Darrell R. , Maxson Pamela M. 
Published: November 2003

Background
The goal of this project was to study the frequency and natural history of perioperative lower extremity neuropathies.

Methods
A prospective evaluation of lower extremity neuropathies in 991 adult patients undergoing general anesthetics and surgical procedures while positioned in lithotomy was performed. Patients were assessed with use of a standard questionnaire and neurologic examination before surgery, daily during hospital stay in the first week after surgery, and by phone if discharged before 1 postoperative week. Patients in whom lower extremity neuropathies developed were observed for 6 months.

Results
Lower extremity neuropathies developed in 15 patients (1.5%; 95% confidence interval, 0.8-2.5%). Unilateral or bilateral nerves were affected in patients as follows: obturator (five patients), lateral femoral cutaneous (four patients), sciatic (three patients), and peroneal (three patients). Paresthesia occurred in 14 of 15 patients, and 4 patients had burning or aching pain. No patient had weakness. Symptoms were noted within 4 h of completion of the anesthetic in all 15 patients. These symptoms resolved within 6 months in 14 of 15 patients. Prolonged positioning in a lithotomy position, especially for more than 2 h, was a major risk factor for this complication (P = 0.006).

Conclusions
In this surgical population, lower extremity neuropathies were infrequent complications that were noted very soon after surgery and anesthesia. None resulted in prolonged disability. The longer patients were positioned in lithotomy positions, the greater the chance of development of a neuropathy. These findings suggest that a reduction of duration of time in lithotomy positions may reduce the risk of lower extremity neuropathies.
Arterial and Venous Contributions to Near-infrared Cerebral Oximetry
Authors: Watzman H. Marc , Kurth C. Dean , Montenegro Lisa M. , Rome Jonathan , Steven James M. , Nicolson Susan C. 
Published: November 2003

Background
Cerebral oximetry is a noninvasive bedside technology using near-infrared light to monitor cerebral oxygen saturation (Sco2) in an uncertain mixture of arteries, capillaries, and veins. The present study used frequency domain near-infrared spectroscopy to determine the ratio of arterial and venous blood monitored by cerebral oximetry during normoxia, hypoxia, and hypocapnia.

Methods
Twenty anesthetized children aged < 8 yr with congenital heart disease of varying arterial oxygen saturation (Sao2) were studied during cardiac catheterization. Sco2, Sao2, and jugular bulb oxygen saturation (Sjo2) were measured by frequency domain near-infrared spectroscopy and blood oximetry at normocapnia room air, normocapnia 100% inspired O2, and hypocapnia room air.

Results
Among subject conditions, Sao2 ranged from 68% to 100%, Sjo2 from 27% to 96%, and Sco2 from 29% to 92%. Sco2 was significantly related to Sao2 (y = 0. 85 x -17, r = 0.47), Sjo2 (y = 0.77 x +13, r = 0.70), and the combination (Sco2 = 0.46 Sao2 + 0.56 Sjo2 - 17, R = 0.71). The arterial and venous contribution to cerebral oximetry was 16 +/- 21% and 84 +/- 21%, respectively (where Sco2 = alpha Sao2 + beta Sjo2 with alpha and beta being arterial and venous contributions). The contribution was similar among conditions but differed significantly among subjects (range, approximately 40:60 to approximately 0:100, arterial:venous).

Conclusions
Cerebral oximetry monitors an arterial/venous ratio of 16:84, similar in normoxia, hypoxia, and hypocapnia. Because of biologic variation in cerebral arterial/venous ratios, use of a fixed ratio is not a good method to validate the technology.
Evaluation of a Cerebral Oximeter as a Monitor of Cerebral Ischemia during Carotid Endarterectomy
Authors: Samra Satwant K. , Dy Eric A. , Welch Kathy , Dorje Pema , Zelenock Gerald B. , Stanley James C. 
Published: November 2003

Background
Stroke is an important contributor to perioperative morbidity and mortality associated with carotid endarterectomy (CEA). This investigation was designed to compare the performance of the INVOS-3100 cerebral oximeter to neurologic function, as a means of detecting cerebral ischemia induced by carotid cross-clamping, in patients undergoing carotid endarterectomy with cervical plexus block.

Methods
Ninety-nine patients undergoing 100 CEAs with regional anesthesia (deep or superficial cervical plexus block) were studied. Bilateral regional cerebrovascular oxygen saturation (rSO2) was monitored using the INVOS-3100 cerebral oximeter. Patients were retrospectively assigned to one of two groups: those in whom a change in mental status or contralateral motor deficit was noted after internal carotid clamping (neurologic symptoms; n = 10) and those who did not show any neurologic change (no neurologic symptoms; n = 90). Data from 94 operations (neurologic symptoms = 10 and no neurologic symptoms = 84) were adequate for statistical analyses for group comparisons. A relative decrease in ipsilateral rSO2 after carotid occlusion (calculated as a percentage of preocclusion value) during all operations (n = 100) was also calculated to determine the critical level of rSO2 decrease associated with a change in neurologic function.

Results
The mean (+/- SD) decrease in rSO2 after carotid occlusion in the neurologic symptoms group (from 63.2 +/- 8.4% to 51.0 +/- 11.6%) was significantly greater (P = 0.0002) than in the no neurologic symptoms group (from 65.8 +/- 8.5% to 61.0 +/- 9.3%). Logistic regression analysis used to determine if a change in rSO2, calculated as a percentage of preclamp value, could be used to predict change in neurologic function was highly significant (likelihood ratio chi-square = 13.7; P = 0.0002). A 20% decrease in rSO2 reading from the preclamp baseline, as a predictor of neurologic compromise, resulted in a sensitivity of 80% and specificity of 82.2%. The false-positive rate using this cutoff point was 66.7%, and the false-negative rate was 2.6%, providing a positive predictive value of 33.3% and a negative predictive value of 97.4%.

Conclusion
Monitoring rSO2 with INVOS-3100 to detect cerebral ischemia during CEA has a high negative predictive value, but the positive predictive value is low.
Electrocardiographic ST-segment Changes during Acute, Severe Isovolemic Hemodilution in Humans
Authors: Leung Jacqueline M. , Weiskopf Richard B. , Feiner John , Hopf Harriet W. , Kelley Scott , Viele Maurene , Lieberman Jeremy , Watson Jessica , Noorani Mariam , Pastor Darwin , Yeap Hooi , Ho Rachel , Toy Pearl 
Published: November 2003

Background
Controversy exists regarding the lowest blood hemoglobin concentration that can be safely tolerated. The authors studied healthy resting humans to test the hypothesis that acute isovolemic reduction of blood hemoglobin concentration to 5 g/dl would produce an imbalance in myocardial oxygen supply and demand, resulting in myocardial ischemia.

Methods
Fifty-five conscious healthy human volunteers were studied. Isovolemic removal of aliquots of blood reduced blood hemoglobin concentration from 12.8 +/- 1.2 to 5.2 +/- 0.5 g/dl (mean +/- SD). Removed blood was replaced simultaneously with intravenous fluids to maintain constant isovolemia. Hemodynamics and arterial oxygen content (Cao2) were measured before and after removal of each aliquot of blood. Electrocardiographic (ECG) changes were monitored continuously using a Holter ECG recorder for detection of myocardial ischemia.

Results
During hemodilution, transient, reversible ST-segment depression developed in three subjects as seen on the electrocardiogram during hemodilution. These changes occurred at hemoglobin concentrations of 5-7 g/dl while the subjects were asymptomatic. Two of three subjects with ECG changes had significantly higher heart rates than those without ECG changes at the same hemoglobin concentrations. When evaluating the entire study period, the subjects who had ECG ST-segment changes had significantly higher maximum heart rates than those without ECG changes, despite having similar baseline values.

Conclusion
With acute reduction of hemoglobin concentration to 5 g/dl, ECG ST-segment changes developed in 3 of 55 healthy conscious adults and were suggestive of, but not conclusive for, myocardial ischemia. The higher heart rates that developed during hemodilution may have contributed to the development of an imbalance between myocardial supply and demand resulting in ECG evidence of myocardial ischemia. However, these ECG changes appear to be benign because they were reversible and not accompanied by symptoms.
Dose–Response and Onset/Offset Characteristics of Rapacuronium
Authors: Kopman Aaron F. , Klewicka Monika M. , Ghori Khurram , Flores Frank , Neuman George G. 
Published: November 2003

Background
A rigorous study of the dose-response relation of rapacuronium has, to our knowledge, yet to be performed. In addition, there is little information available regarding the onset or offset profile of rapacuronium when administered in subparalyzing doses. These issues necessitate further study.

Methods
Forty-seven adult patients, American Society Anesthesiologists physical status I or II, were studied. Tracheal intubation was accomplished without muscle relaxants. Anesthesia was maintained with use of nitrous oxide, propofol, and alfentanil. The electromyogram of the first dorsal interosseous muscle was measured using a monitor. Single stimuli at 0.10 Hz were administered. A single dose of rapacuronium was administered. After log-dose or logit transformation of the data, the best-fit line of regression was determined using the method of least squares. For each subject, the authors estimated the 50% effective dose (ED50) and 95% effective dose (ED95) from the Hill equation using the slope obtained from regression analysis. The onset times to 50 and 90% of peak effect were estimated in a subset of 10 individuals in which peak twitch depression decreased to the range of 90-99%.

Results
The calculated ED50 and ED95 values for rapacuronium were 0.39 +/- 0.08 (SD) and 0.75 +/- 0.16 mg/kg, respectively. After a single ED95 dose, 90% of the drug's peak effect was evident in 77 +/- 17 s. After this dose, rapacuronium has a clinical duration of 6.1 +/- 1.1 min.

Conclusions
The authors found the ED95 of rapacuronium to be substantially less than suggested by previous estimates. Rapacuronium has an onset profile that is not different from that previously reported for succinylcholine. The rate of spontaneous recovery was faster after rapacuronium than the authors previously observed after mivacurium administration but was slower than after succinylcholine, using an identical protocol.