bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cesarean Delivery
Authors: Sharma Shiv K. , Sidawi Elaine J. , Ramin Susan M. , Lucas Michael J. , Leveno Kenneth J. , Cunningham Gary F. 
Published: November 2003

Background
Reports indicate that the administration of epidural analgesia for pain relief during labor interferes with labor and increases cesarean deliveries. However, only a few controlled trials have assessed the effect of epidural analgesia on the incidence of cesarean delivery. The authors' primary purpose in this randomized study was to evaluate the effects of epidural analgesia on the rate of cesarean deliveries by providing a suitable alternative: patient-controlled intravenous analgesia.

Methods
Seven hundred fifteen women of mixed parity in spontaneous labor at full term were randomly assigned to receive either epidural analgesia or patient-controlled intravenous meperidine analgesia. Epidural analgesia was maintained with a continuous epidural infusion of 0.125% bupivacaine with 2 microg/ml fentanyl. Patient-controlled analgesia was maintained with 10-15 mg meperidine given every 10 min as needed using a patient-controlled pump. Procedures recorded in a manual that prescribed the intrapartum management were followed for each woman randomized in the study.

Results
A total of 358 women were randomized to receive epidural analgesia, and 243 (68%) of these women complied with the epidural analgesia protocol. Similarly, 357 women were randomized to receive patient-controlled intravenous meperidine analgesia, and 259 (73%) of these women complied with the patient-controlled intravenous analgesia protocol. Only five women who were randomized and received patient-controlled intravenous meperidine analgesia according to the protocol crossed over to epidural analgesia due to inadequate pain relief. There was no difference in the rate of cesarean deliveries between the two analgesia groups using intention-to-treat analysis based on the original randomization (epidural analgesia, 4% [95% CI: 1.9-6.2%] compared with patient-controlled intravenous analgesia, 5% [95% CI: 2.6-7.2%]). Similar results were observed for the analysis of the protocol-compliant groups (epidural analgesia, 5% [95% CI: 2.6-8.5%] compared with patient-controlled intravenous analgesia, 6% [95% CI: 3-8.9%]). Women who received epidural analgesia reported lower pain scores during labor and delivery compared with women who received patient-controlled intravenous analgesia.

Conclusions
Epidural analgesia was not associated with increased numbers of cesarean delivery when compared with a suitable alternative method of analgesia.
Monitoring Gastric Mucosal Carbon Dioxide Pressure Using Gas Tonometry
Authors: Creteur Jacques , De Backer Daniel , Vincent Jean-Louis 
Published: November 2003

Background
Saline gastric tonometry of carbon dioxide has been proposed as a means to assess the adequacy of splanchnic perfusion. However, this technique has several disadvantages, including the long time interval needed for gases to reach equilibrium in saline milieu. Thus the authors evaluated a system that uses a gas-filled instead of a saline-filled gastric balloon.

Methods
In vitro, we simultaneously placed two tonometry catheters in an equilibration water bath maintained at a predetermined and constant pressure of carbon dioxide (P(CO2)). The first catheter's balloon was filled with air and the second with saline. The performance of gas tonometry was tested by comparing the P(CO2) measurements of the bath obtained via gas tonometry (PgCO2) to the P(CO2) measurements of direct bath samples (PbathCO2). These results were also compared with the P(CO2) measurements obtained simultaneously by saline tonometry (PsCO2). The response time of gas versus saline tonometry was also studied. In vivo, the performance of gas tonometry was tested comparing the measurements of gastric intramucosal P(CO2) obtained by gas tonometry (PgCO2) at different equilibration times with those obtained by saline tonometry (PsCO2) using an equilibration time of 30 min. Two nasogastric tonometry catheters were placed simultaneously in seven stable patients in the intensive care unit. The first balloon was filled with air and the second with saline.

Results
In vitro, there was a close correlation between PgCO2 and PbathCO2, for each level of PbathCO2, and for each different gas equilibration time. For an equilibration time of 10 min at a PbathCO2 level of approximately 40 mmHg, the bias of the gas device defined as the mean of the differences between PbathCO2 and PgCO2 and its precision defined as the standard deviation of the bias, were -0.3 mmHg and 0.7 mmHg, respectively. Using the same definitions, the bias and precision of saline tonometry were 11.2 mmHg and 1.4 mmHg, respectively. If the equilibration time-dependent correction factor provided by the catheter manufacturer for saline tonometry was applied, the bias and precision were -6.9 mmHg and 2.9 mmHg, respectively. In vivo, using an equilibration time of 10 min for gas and 30 min for saline tonometry, there was a close correlation between the two techniques (r2 = 0.986). A Bland and Altman analysis revealed a bias (+/- 2 SD) of 0.1 +/- 6.8 mmHg. The correlation between the two methods was not improved if we prolonged the equilibration time of the gas tonometer.

Conclusions
Gas tonometry is comparable to saline tonometry for measuring gastric intramucosal P(CO2). Because gas tonometry is easier to automate, it may offer advantages over saline tonometry.
Blood Flow Velocity of Middle Cerebral Artery during Prolonged Anesthesia with Halothane, Isoflurane, and Sevoflurane in Humans
Authors: Kuroda Yasuhiro , Murakami Mari , Tsuruta Junko , Murakawa Toshisuke , Sakabe Takefumi 
Published: November 2003

Background
It is not clear whether the increase of cerebral blood flow (CBF) produced by volatile anesthetics is maintained during prolonged anesthesia. In a previous study, the authors found that CBF equivalent, an index of flow-metabolism relationship, was stable over 3 h, suggesting no decay over time in CBF for 3 h during volatile anesthesia in humans. However, it may be possible that CBF changes in a parallel fashion to functional metabolic changes. In this study, to estimate the response of CBF to three volatile anesthetics, the authors used transcranial Doppler (TCD) ultrasonography to measure time-averaged mean velocity in the middle cerebral artery (Vmca).

Methods
Twenty-four surgical patients were randomly assigned to three groups to receive halothane, isoflurane, or sevoflurane (eight patients, each). End-tidal concentration of the selected volatile anesthetic was maintained at 0.5, 1.0, and 1.5 MAC before surgery and then at 1.5 MAC during surgery, which lasted more than 3 h. Normothermia and normocapnia were maintained. Mean arterial blood pressure was kept above 70 mmHg, using phenylephrine infusion, if necessary. TCD recordings of the Vmca were performed continuously.

Results
Vmca at 0.5 MAC of halothane, isoflurane, and sevoflurane was 49 +/- 19, 57 +/- 8, and 48 +/- 13 cm/s, respectively. Halothane significantly (P < 0.01) increased Vmca in a dose-dependent manner (0.5, 1.0, 1.5 MAC), whereas isoflurane and sevoflurane produced no significant dose-related changes. At 1.5 MAC for 3 h, Vmca changed significantly (P < 0.05) for the time trends, but it did not exhibit decay over time with all drugs. During burst suppression, observed electroencephalographically (EEG) on patients during isoflurane and sevoflurane anesthesia, the onset of a burst increased Vmca (approximately 5-30 cm/s), which was maintained for the duration of the burst.

Conclusions
The results indicate that there was no decay in Vmca over time during prolonged (3 h) inhalation of volatile anesthetics at 1.5 MAC in humans. The fluctuation of Vmca during burst suppression on EEG at 1.5 MAC indicates that the flow-metabolism coupling occurred.
Prevention of Methacholine-induced Changes in Respiratory Mechanics in Piglets
Authors: Habre Walid , Wildhaber Johannes H. , Sly Peter D. 
Published: November 2003

Background
Sevoflurane is a new volatile anesthetic agent that may be a useful alternative to halothane for anesthesia in children. However, there is insufficient information about its effects on respiratory mechanics, particularly in the presence of constrictor stimuli.

Methods
Eighteen piglets had anesthesia induced and maintained with either pentobarbital (control: n = 8), 1 minimum alveolar concentration (MAC) sevoflurane (sevo: n = 5), or 1 MAC halothane (halo: n = 5). Pressure, flow, and volume were measured at the airway opening and used to calculate lung compliance (C(L)) and resistance (R(L)). Resistance was partitioned into airway (Raw) and parenchymal (Vti) components using alveolar pressure. Methacholine was infused intravenously in a dose sufficient (15 microg x kg(-1) x h(-1)) to approximately double R(L).

Results
The increase in R(L) seen in the control group was almost entirely due to an increase in Vti. Sevoflurane and halothane prevented the increase in R(L) and Vti (both P < 0.02) and the decrease in C(L) (both P < 0.02).

Conclusions
Sevoflurane and halothane can prevent methacholine-induced changes in lung function.
Pregnancy Does Not Increase Susceptibility to Bupivacaine in Spinal Root Axons
Authors: Dietz Friederike B. , Jaffe Richard A. 
Published: November 2003

Background
The underlying mechanism of enhanced antinociceptive effects and increased susceptibility to local anesthetics during pregnancy is not known. Mechanical, hormonal, biochemical, and neural changes have been suggested. The authors measured the susceptibility of individual spinal root axons to bupivacaine during late pregnancy in rats and compared them with similar measurements in nonpregnant rats.

Methods
Lumbar dorsal and ventral roots were excised from anesthetized pregnant and nonpregnant rats. Single-fiber dissection and recording techniques were used to isolate activity in individual axons. Supramaximal constant voltage stimuli were delivered to the distal end of the root. During in vitro perfusion, each root was exposed to increasing concentrations of bupivacaine, and the minimum blocking concentration (Cm) and the concentration that increased conduction latency by 50% (EC50) were measured.

Results
Myelinated and unmyelinated dorsal and ventral root axons of pregnant rats appeared to be less sensitive to steady-state conduction block and to the latency-increasing effects of bupivacaine than were equivalent axons from nonpregnant rats. Although when comparing specific axon types, only the difference in C-fibers was significant (Cm = 29.8 microM for pregnant and Cm = 22.1 microM for nonpregnant rats, P < 0.05; EC50 = 19.9 microM and 13.6 microM, respectively).

Conclusions
In contrast to clinical expectations, the susceptibility to bupivacaine conduction block in individual dorsal and ventral root axons during late pregnancy in rats was not greater in pregnant animals. Pregnancy-related changes in diffusion barriers and activation of endogenous analgesic systems without changes in the electrophysiologic properties of spinal root axons are suggested as possible explanations for the discrepancy between clinical and experimental observations.
Neutrophil Elastase Inhibitor, ONO-5046, Modulates Acid-induced Lung and Systemic Injury in Rabbits
Authors: Kaneko Kazuhiro , Kudoh Ichidai , Hattori Satoshi , Yamada Hiroshi , Ohara Maria , Wiener-Kronish Jeanine , Okumura Fukuichiro 
Published: November 2003

Background
Acid instillation leads to direct lung and to secondary systemic organ injury, probably via activated macrophages and neutrophils. This study investigated the effects of neutrophil elastase on organ injury after unilateral lung acid instillation by administrating a specific neutrophil elastase inhibitor, ONO-5046, before acid instillation.

Methods
Three groups of anesthetized rabbits (n = 12 in each group) underwent tracheostomies, and instillations were made into their right lower lobe airspaces with either phosphate buffered saline (pH, 7.4; volume, 1.2 ml/kg; n = 12) or HCl (pH, 1.25; volume, 1.2 ml/kg; n = 24). In half of the acid-instilled rabbits, ONO-5046, 10 mg/kg, was given intravenously 15 min before the HCl instillation, and then 10 mg x kg(-1) x h(-1) of the drug was continuously infused throughout the experiment. The other groups of animals received the vehicle intravenously. Anesthesia and mechanical ventilation was continued for 8 h, whereas arterial blood gases were sampled intermittently. Eight hours after saline or acid instillation, the animals were killed, and their lungs, heart, kidneys, liver, and small intestines were harvested. Wet-to-dry weight ratios (W/ D) and myeloperoxidase (MPO) assays of these organs were done, and elastase assays on the bronchoalveolar lavage fluids (BALF) obtained from each lung also were performed.

Results
Pretreatment with ONO-5046 attenuated the physiologic changes seen in the vehicle-treated animals. Significant decreases in W/D of the noninstilled lungs and of the small intestine and normalization of the oxygenation of the experimental animals occurred. The ONO-5046 pretreatment did not affect the neutrophil sequestration in the lungs or in the other organs as determined by neutrophil counts in BALF and by the MPO assays.

Conclusions
A neutrophil elastase inhibitor, ONO-5046, administered immediately before acid instillation attenuated the physiologic changes seen in the vehicle-treated animals. The drug blocked neutrophil elastase but did not block neutrophil sequestration in the lungs, although the drug improved measurements of lung injury.
Nitrous Oxide Impairs Electrophysiologic Recovery after Severe Hypoxia in Rat Hippocampal Slices
Authors: Amorim Pedro , Chambers Geoffrey , Cottrell James , Kass Ira S. 
Published: November 2003

Background
Research has suggested that nitrous oxide may be harmful to ischemic neurons; however, the evidence for this is equivocal. The authors used rat hippocampal slices to examine the effects of nitrous oxide on neuronal hypoxic damage.

Methods
The evoked population spike (PS) was recorded from hippocampal CA1 pyramidal cells before, during, and after hypoxia. Control groups received nitrogen concentrations equal to nitrous oxide throughout the experiments. Biochemical measurements were made from dissected CA1 regions under experimental conditions that matched the electrophysiology studies.

Results
Recovery of the PS after hypoxia was 18 +/- 7% in slices treated with 50% nitrous oxide before and during 3.5 min of hypoxia; this compares with 41 +/- 9% (P < 0.05) in nitrogen-treated slices. Slices treated with nitrous oxide (95%) only during hypoxia (6 min) also demonstrated significantly less recovery of the PS than did slices treated with nitrogen. There was no significant difference in recovery if nitrous oxide was discontinued after the hypoxic period. Adenosine triphosphate concentrations after 3.5 min of hypoxia in slices treated with nitrous oxide decreased to the same extent as in nitrogen-treated slices (47% vs. 50%). Calcium influx increased during 10 min of hypoxia in untreated slices, but nitrous oxide did not significantly increase calcium influx during hypoxia. The sodium concentrations increased and potassium concentrations decreased during hypoxia; nitrous oxide did not significantly alter these changes.

Conclusions
Nitrous oxide impaired electrophysiologic recovery of hippocampal slices after severe hypoxia. Nitrous oxide did not cause significant changes in the biochemical parameters examined.
Effects of Intracoronary Fentanyl on Left Ventricular Mechanoenergetics in the Excised Cross-circulated Canine Heart (Revised Publication)
Authors: Kohno Kunihisa , Takaki Miyako , Ishioka Kazunari , Nakayama Yasunori , Suzuki Shunsuke , Araki Junichi , Namba Taketoshi , Suga Hiroyuki 
Published: November 2003

Background
It is still unclear whether fentanyl directly alters left ventricular (LV) contractility and oxygen consumption. This is because of the difficulty in defining and evaluating contractility and energy use independently of ventricular loading conditions and heart rate in beating whole hearts.

Methods
This study was conducted to clarify the mechanoenergetic effects of intracoronary fentanyl in six excised cross-circulated canine hearts. The authors used the framework of the Emax (a contractility index)-PVA (systolic pressure-volume area, a measure of total mechanical energy)-VO2 (myocardial oxygen consumption per beat) relationship practically independent of ventricular loading conditions. The authors measured LV pressure, volume, coronary flow, and arteriovenous oxygen content difference to calculate Emax, PVA, and VO2. They first obtained the VO2-PVA relationship for varied LV volumes at control Emax. The authors then obtained the VO2-PVA relationship at a constant LV volume, whereas coronary blood fentanyl concentration was increased in steps up to 240 ng/ml. Finally, they obtained the VO2-PVA relationship for varied LV volumes at the final dose of fentanyl.

Results
Fentanyl at any concentrations did not significantly change Emax, PVA, and VO2 from the control. The linear end-systolic pressure-volume relations and their slopes were virtually the same between the control and fentanyl volume loading in each heart. Further, either the slope (oxygen cost of PVA) or the VO2 intercept (unloaded VO2) of the linear VO2-PVA relationship remained unchanged by fentanyl.

Conclusions
These results indicate that intracoronary fentanyl produces virtually no effects on LV mechanoenergetics for a wide range of its blood concentration.
Comparative Hemodynamic Depression of Sevoflurane versus Halothane in Infants
Authors: Wodey Eric , Pladys Patrick , Copin Catherine , Lucas Marie Madeleine , Chaumont Andre , Carre Philippe , Lelong Bernard , Azzis Olivier , Ecoffey Claude 
Published: November 2003

Background
The cardiovascular side effects of volatile anesthetics are one of the chief causes of postoperative complications in children, and infants seem to be at the greatest risk for this. This study compared cardiovascular changes at equipotent concentrations of sevoflurane and halothane in infants.

Methods
Thirty infants classified as American Society of Anesthesiologists physical status I or II who required elective surgery were randomized to receive either halothane or sevoflurane for inhalation induction. Cardiovascular and echocardiographic data were recorded in both groups at baseline and at end-tidal concentrations of 1 and 1.5 minimum alveolar concentration (MAC).

Results
Sevoflurane did not alter heart rate or cardiac index at all concentrations compared with awake values. Sevoflurane significantly decreased blood pressure and systemic vascular resistance compared with awake values at all concentrations. Shortening fraction and rate-corrected velocity of circumferential fiber shortening decreased at 1.5 but not at 1 MAC. Myocardial contractility assessed by stress-velocity index and stress-shortening index decreased significantly at all concentrations, but did not fall into the abnormal range at any concentration. Halothane caused a greater decrease in heart rate, shortening fraction, stress-shortening index, velocity of circumferential fiber shortening, stress-velocity index, and cardiac index at all concentrations than did sevoflurane.

Conclusion
Sevoflurane causes a lesser decrease in cardiac output than does halothane in infants.
Predictive Factors in Global and Anesthesia Satisfaction in Ambulatory Surgical Patients
Authors: Tong Doris , Chung Frances , Wong David 
Published: November 2003

Background
Patient satisfaction is one of the variables that affect the outcome of health care and the use of health-care services. As more procedures are performed on an ambulatory basis, the role of the anesthesiologist becomes more important. To improve the delivery of care, the predictors of dissatisfaction with the entire process (global dissatisfaction) of ambulatory surgery and with anesthesia itself must be identified. The authors conducted a hypothesis-generating study to identify predictors; specifically, they hypothesized that satisfaction with anesthesia was a predictor of global satisfaction with ambulatory surgery and that 24-h postoperative symptoms were a predictor of satisfaction with anesthesia.

Methods
The authors prospectively studied 5,228 consecutive patients having surgery in the ambulatory setting during a 1-yr period. Preoperative, intraoperative, and postoperative variables were gathered and patient satisfaction was assessed using a postoperative telephone questionnaire administered 24 h after operation in 2,730 respondents. Significant univariate variables and clinically important variables were entered into multiple logistic regression models. Qualitative data on dissatisfaction were obtained by asking patients' reasons for dissatisfaction.

Results
Sixty-eight of the 2,730 respondents (2.5%) had global dissatisfaction with ambulatory surgery. Nine of these patients were dissatisfied with anesthesia. Dissatisfaction with anesthesia was associated with a 12-fold increase in global dissatisfaction (P = 0.0001). Thirty-one of the 2,730 respondents (1.1%) were dissatisfied with anesthesia. An increasing number of symptoms occurring 24 h after operation was associated with an exp(0.28 x N)-fold increase in dissatisfaction with anesthesia for N number of symptoms (P = 0.0001). Qualitative data showed that the most common reason for global dissatisfaction with ambulatory surgery was personal preference for inpatient care (26%), whereas intraoperative and postoperative adverse outcomes were the major causes of dissatisfaction with anesthesia (88%).

Conclusions
Dissatisfaction with anesthesia is a predictor of global dissatisfaction with ambulatory surgery. An increasing number of symptoms 24 h after operation is a predictor of dissatisfaction with anesthesia. The rate of global dissatisfaction and anesthesia dissatisfaction is very low. The predictors from this model need to be validated by a second data set from either this or another center. Given the low rate of dissatisfaction, a focused study testing specific interventions to improve patient satisfaction would be difficult.
Development of a Measure of Patient Satisfaction with Monitored Anesthesia Care
Authors: Dexter Franklin , Aker John , Wright Will A. 
Published: November 2003

Background
The authors describe development of the Iowa Satisfaction with Anesthesia Scale (ISAS) for monitored anesthesia care (MAC). Patients complete the self-administered written questionnaire before discharge from the hospital. The authors designed the ISAS to measure satisfaction with MAC itself, not the perioperative experience. Patients respond to eleven statements (e.g., "I felt pain") by placing a mark along a six-choice vertical response column (e.g., "Disagree moderately") below each statement. The mean of their responses to each of the 11 statements gives a single number, which is a quantitative measure of a patient's satisfaction with their MAC.

Methods
Adult, English-speaking patients completed the questionnaires following admission to a phase II postanesthesia care unit after MAC.

Results
Response rate for MAC was 92% (86 of 94 patients). Patients completed the questionnaire in 4.6 +/- 2.3 min. Internal consistency, Cronbach's alpha, equaled 0.80. Patients' scores were positively correlated with those predicted by their anesthesia provider (r2 = 0.23) and with responses to the question "I was satisfied with my anesthetic care" (Kendall's tau = +0.41). Scores on initial and repeat questionnaires were positively correlated (r2 = 0.74). Scores on initial questionnaires and those completed within 4.4 +/- 1.7 days postoperatively were positively correlated (r2 = 0.76).

Conclusions
The authors have developed and tested an internally consistent, reliable, and valid measure of patient satisfaction with MAC.