bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rehydration of Desiccated Baralyme Prevents Carbon Monoxide Formation from Desflurane in an Anesthesia Machine
Authors: Baxter Pamela J. , Kharasch Evan D. 
Published: November 2003

Background
Desiccated carbon dioxide absorbents degrade desflurane, enflurane, and isoflurane to carbon monoxide (CO) in vitro and in anesthesia machines, which can result in significant clinical CO exposure. Carbon monoxide formation is highest from desflurane, and greater with Baralyme than with soda lime. Degradation is inversely related to absorbent water content, and thus the greatest CO concentrations occur with desflurane and fully desiccated Baralyme. This investigation tested the hypothesis that rehydrating desiccated absorbent can diminish CO formation.

Methods
Baralyme was dried to constant weight. Carbon monoxide formation from desflurane and desiccated Baralyme was determined in sealed 20.7-ml vials without adding water, after adding 10% of the normal water content (1.3% water), and after adding 100% of the normal water content (13% water) to the dry absorbent. Similar measurements were made using an anesthesia machine and circle system. Carbon monoxide was measured by gas chromatography-mass spectrometry.

Results
Carbon monoxide formation from desflurane in vitro was decreased from 10,700 ppm with desiccated Baralyme to 715 ppm and less than 100 ppm, respectively, when 1.3% and 13% water were added. Complete rehydration also decreased CO formation from enflurane and isoflurane to undetectable concentrations. Desflurane degradation in an anesthesia machine produced 2,500 ppm CO in the circuit, which was reduced to less than 180 ppm when the full complement of water (13%) was added to the dried absorbent.

Conclusions
Desflurane is degraded by desiccated Baralyme in an anesthesia machine, resulting in CO formation. Adding water to dried Baralyme is an effective means of reducing CO formation and the risk of intraoperative CO poisoning. Although demonstrated specifically for desflurane and Baralyme, rehydration is also applicable to enflurane and isoflurane, and to soda lime.
Isoflurane- and Halothane-mediated Dilation of Distal Bronchi in the Rat Depends on the Epithelium
Authors: Park Kyung W. , Dai Hai B. , Lowenstein Edward , Kocher Olivier N. , Sellke Frank W. 
Published: November 2003

Background
Respiratory epithelium releases substance(s) that can modulate bronchoconstriction in response to constrictive agonists and enhance bronchodilation in response to certain bronchodilators. The hypothesis that the bronchodilatory effect of isoflurane and halothane depends on the epithelium was tested in rat distal bronchial segments.

Methods
Wistar rat bronchial segments of the fourth order (diameter approximately 100 microns) were dissected. After preconstriction with 5-hydroxytryptamine, each bronchial segment was exposed to increasing concentrations of 0% to 3% isoflurane or 0% to 3% halothane under four conditions: after epithelial rubbing, after pretreatment with the nitric oxide synthase inhibitor NG-nitro-L-arginine, after pretreatment with the cyclooxygenase inhibitor indomethacin, or with no preintervention (control). Changes in bronchial diameter were monitored using an in vitro video detection system.

Results
Both isoflurane and halothane produced concentration-dependent bronchodilation (P < 0.001 for either anesthetic; 40% +/- 11% [mean +/- SD] dilation for 3% isoflurane and 57% +/- 10% dilation for 3% halothane). For both anesthetics, bronchodilation was significantly but incompletely attenuated by epithelial rubbing (12% +/- 7% dilation for 3% isoflurane [P < 0.01] and 31% +/- 10% dilation for 3% halothane [P < 0.01]), by pretreatment with indomethacin (20% +/- 8% dilation for 3% isoflurane [P < 0.02] and 21% +/- 9% dilation for 3% halothane [P < 0.001]), or by L-NNA (9% +/- 7% dilation for 3% isoflurane [P < 0.005] and 39% +/- 12% dilation for 3% halothane [P < 0.05]). Epithelial rubbing did not impair nitroprusside-associated bronchodilation.

Conclusions
Isoflurane- and halothane-mediated bronchodilation depends at least partially on the epithelium and may involve both a prostanoid and nitric oxide in distal rat bronchi.
Mild and Moderate Hypothermia Provide Better Protection than a Burst-suppression Dose of Thiopental against Ischemic Spinal Cord Injury in Rabbits
Authors: Matsumoto Mishiya , Iida Yasuhiko , Sakabe Takafumi , Sano Takanobu , Ishikawa Toshizo , Nakakimura Kazuhiko 
Published: November 2003

Background
Controversy exists over the efficacy of different methods for protecting the spinal cord against experimental ischemic injury. Therefore, the authors compared the protective effects of thiopental with those of hypothermia (35 degrees C and 32 degrees C) on hindlimb motor functions and histopathology after transient spinal cord ischemia.

Methods
Twenty-seven New Zealand white rabbits were assigned to one of the four groups: a thiopental-normothermia group (burst-suppression dose of thiopental; esophageal temperature = 38 degrees C; n = 7), a halothane-mild hypothermia group (halothane, 1%; esophageal temperature = 35 degrees C; n = 7), a halothane-moderate hypothermia group (halothane, 1%; esophageal temperature = 32 degrees C; n = 6), and a halothane-normothermia group (halothane, 1%; esophageal temperature = 38 degrees C; n = 7). The animals were then subjected to 20 min of spinal cord ischemia produced by occlusion of the aorta distal to the origin of left renal artery. Hindlimb motor function was observed for 48 h after reperfusion. Histopathology of the lumbar spinal cord also was examined.

Results
All animals in the halothane-mild hypothermia and halothane-moderate hypothermia groups were neurologically normal 48 h after ischemia. There was no statistical difference in the final neurologic status and histopathology between the thiopental-normothermia and halothane-normothermia groups. However, the final neurologic status and histopathology in both groups were worse than in the halothane-mild hypothermia or halothane-moderate hypothermia groups. There was a strong correlation between the final neurologic status and the numbers of normal neurons in the anterior spinal cord.

Conclusions
These results suggest that mild and moderate hypothermia protects against ischemic spinal cord injury in rabbits, and a burst-suppression dose of thiopental does not offer any advantage over halothane.
Role of Adenosine in Isoflurane-induced Cardioprotection
Authors: Kersten Judy R. , Orth Karl G. , Pagel Paul S. , Mei David A. , Gross Garrett J. , Warltier David C. 
Published: November 2003

Background
This investigation tested the hypothesis that adenosine (A1) receptor blockade modulates the cardioprotective effects of isoflurane.

Methods
Hemodynamics and percentage segment shortening (%SS) in the left anterior descending coronary artery (LAD) perfusion territory were evaluated in barbiturate-anesthetized dogs (n = 31) at selected intervals after pretreatment with the selective A1 receptor antagonist (8-cyclopentyl-1,3,dipropyl-xanthine; DPCPX 0.8 mg/kg, intravenously) or drug vehicle in the presence or absence of 1 minimum alveolar concentration (MAC) isoflurane. Dogs were subjected to five 5-min occlusions and reperfusions of the LAD, followed by 180 min of final reperfusion. Isoflurane was administered for 30 min before and during LAD occlusions and reperfusions and was discontinued at the onset of final reperfusion. Two other groups of dogs (n = 17) were used to measure interstitial concentrations of purines in the LAD region using a microdialysis technique in the presence and absence of isoflurane.

Results
Dogs receiving drug vehicle or DPCPX exhibited no recovery of %SS after 180 min of reperfusion (-5 +/- 7 and 5 +/- 11% of baseline, respectively, +/- SEM). In contrast, dogs receiving isoflurane alone demonstrated complete recovery of %SS at 60 min after reperfusion. DPCPX pretreatment partially attenuated isoflurane-induced enhancement of recovery of %SS (34 +/- 11% of baseline 180 min after reperfusion; P < 0.05). Interstitial purine concentrations were increased during multiple occlusions and reperfusions of the LAD in dogs not receiving isoflurane, but they were unchanged by coronary artery occlusion and reperfusion in dogs receiving isoflurane.

Conclusions
The results indicate that isoflurane-induced cardioprotection in stunned myocardium is partially mediated by adenosine type 1 receptor activation and is accompanied by decreases in endogenous adenosine release.
The Successful Implementation of Pharmaceutical Practice Guidelines
Authors: Lubarsky David A. , Glass Peter S. A. , Ginsberg Brian , de Dear Guy L. , Dentz Mark E. , Gan Tong J. , Sanderson Iain C. , Mythen Monty G. , Dufore Sherry , Pressley C. Christopher , Gilbert William C. , White William D. , Alexander M. Lynne , Coleman Robert L. , Rogers Mark , Reves J.G. 
Published: November 2003

Background
Although approximately 2,000 medical practice guidelines have been proposed, few have been successfully implemented and sustained. We hypothesized that we could develop and institute practice guidelines to promote more appropriate use of costly anesthetics, to generate and sustain widespread compliance from a large physician group, and to decrease costs without adversely affecting clinical outcomes.

Methods
A prospective before and after comparison study was performed at a tertiary care medical center. Clinical outcomes data and times indicative of perioperative patient flow were collected on the first of two sets of patients 1 month before discussion of practice guidelines. Practice guidelines were developed by the physicians and their associated care team for the intraoperative use of anesthetic drugs. A drug distribution process was developed to aid compliance. Clinical outcomes data and times indicative of perioperative patient flow were collected on the second set of patients 1 month after institution of practice guidelines. Hospital drug costs and adherence to guidelines were noted throughout the study period and for each of the following 9 months by querying the database of an automated anesthesia record keeper.

Results
A total of 1,744 patients were studied. Drug costs decreased from 56 dollars per case to 32 dollars per case as a result of adherence to practice guidelines. Perioperative patient flow was minimally affected. Time (mean +/- SD) from end of surgery to arrival in the post-anesthesia care unit (PACU) increased from 11 +/- 7 min before the authors instituted practice guidelines to 14 +/- 8 min after practice guidelines (P < 0.0001). Admission of inpatients to the PACU receiving monitored anesthesia care increased from 6.5 to 12.9% (P < 0.02). Perioperative patient flow and clinical outcomes were not otherwise adversely affected. Compliance and cost savings have been sustained.

Conclusions
This study is an example of a successful physician-directed program to promote more appropriate utilization of health care resources. Cost savings were obtained without any substantial changes in clinical outcomes. Institution of similar practice guidelines should result in pharmaceutical savings in the range of 50% at tertiary care centers around the country, with a slightly smaller degree of savings expected at institutions with more ambulatory surgery.
Effects of Low-flow Sevoflurane Anesthesia on Renal Function
Authors: Bito Hiromichi , Ikeuchi Yukako , Ikeda Kazuyuki 
Published: November 2003

Background
The safety of low-flow sevoflurane anesthesia, during which CF2=C(CF3)-O-CH2F (compound A) is formed by sevoflurane degradation, in humans has been questioned because compound A is nephrotoxic in rats. Several reports have evaluated renal function after closed-circuit or low-flow sevoflurane anesthesia, using blood urea nitrogen (BUN) and serum creatinine as markers. However, these are not the more sensitive tests for detecting renal damage. This study assessed the effects of low-flow sevoflurane anesthesia on renal function using not only BUN and serum creatinine but also creatinine clearance and urinary excretion of kidney-specific enzymes, and it compared these values with those obtained in high-flow sevoflurane anesthesia and low-flow isoflurane anesthesia.

Methods
Forty-eight patients with gastric cancer undergoing gastrectomy were studied. Patients were randomized to receive sevoflurane anesthesia with fresh gas flow of 1 l/min (low-flow sevoflurane group; n = 16) or 6-10 l/min (high-flow sevoflurane group; n = 16) or isoflurane anesthesia with a fresh gas flow of 1 l/min (low-flow isoflurane group; n = 16). In all groups, the carrier gas was oxygen/nitrous oxide in the ratio adjusted to ensure a fractional concentration of oxygen in inspired gas (FiO2) of more than 0.3. Fresh Baralyme was used in the low-flow sevoflurane and low-flow isoflurane groups. Glass balls were used instead in the high-flow sevoflurane group, with the fresh gas flow rate adjusted to eliminate rebreathing. The compound A concentration was measured by gas chromatography. Gas samples taken from the inspiratory limb of the circle system at 1-h intervals were analyzed. Blood samples were obtained before and on days 1, 2, and 3 after anesthesia to measure BUN and serum creatinine. Twenty-four-hour urine samples were collected before anesthesia and for each 24-h period from 0 to 72 h after anesthesia to measure creatinine, N-acetyl-beta-D-glucosaminidase, and alanine aminopeptidase.

Results
The average inspired concentration of compound A was 20 +/- 7.8 ppm (mean +/- SD), and the average duration of exposure to this concentration was 6.11 +/- 1.77 h in the low-flow sevoflurane group. Postanesthesia BUN and serum creatinine concentrations decreased, creatinine clearance increased, and urinary N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase excretion increased in all groups compared with preanesthesia values, but there were no significant differences between the low-flow sevoflurane, high-flow sevoflurane, and low-flow isoflurane groups for any renal function parameter at any time after anesthesia.

Conclusions
The only difference between the low-flow and high-flow sevoflurane groups was compound A formation, and postanesthesia laboratory data showed no significant effects of compound A formation during sevoflurane anesthesia on renal function. No significant effects on renal function were observed in either the low-flow or high-flow sevoflurane groups compared with the low-flow isoflurane group.
Hypoxic Pulmonary Vasoconstriction in Nonventilated Lung Areas Contributes to Differences in Hemodynamic and Gas Exchange Responses to Inhalation of Nitric Oxide
Authors: Benzing Albert , Mols Georg , Brieschal Thomas , Geiger Klaus 
Published: November 2003

Background
Enhancement of hypoxic pulmonary vasoconstriction (HPV) in nonventilated lung areas by almitrine increases the respiratory response to inhaled nitric oxide (NO) in patients with acute respiratory distress syndrome (ARDS). Therefore the authors hypothesized that inhibition of HPV in nonventilated lung areas decreases the respiratory effects of NO.

Methods
Eleven patients with severe ARDS treated by venovenous extracorporeal lung assist were studied. Patients' lungs were ventilated at a fraction of inspired oxygen (F[I(O2)]) of 1.0. By varying extracorporeal blood flow, mixed venous oxygen tension (P[O2]; partial oxygen pressure in mixed venous blood [PV(O2)]) was adjusted randomly to four levels (means, 47, 54, 64 and 84 mmHg). Extracorporeal gas flow was adjusted to prevent changes in mixed venous carbon dioxide tension [PV(CO2)]). Hemodynamic and gas exchange variables were measured at each level before, during, and after 15 ppm NO.

Results
Increasing PV(O2) from 47 to 84 mmHg resulted in a progressive decrease in lung perfusion pressure (PAP-PAWP; P < 0.05) and pulmnonary vascular resistance index (PVRI; P < 0.05) and in an increase in intrapulmonary shunt (Q[S]/Q[T]; P < 0.05). PV(CO2) and cardiac index did not change. Whereas the NO-induced reduction in PAP-PAWP was smaller at high PV(O2), NO-induced decrease in Q(S)/Q(T) was independent of baseline PV(O2). In response to NO, arterial P(O2) increased more and arterial oxygen saturation increased less at high compared with low PV(O2).

Conclusion
In patients with ARDS, HPV in nonventilated lung areas modifies the hemodynamic and respiratory response to NO. The stronger the HPV in nonventilated lung areas the more pronounced is the NO-induced decrease in PAP-PAWP. In contrast, the NO-induced decrease in Q(S)/Q(T) is independent of PV(O2) over a wide range of PV(O2) levels. The effect of NO on the arterial oxygen tension varies with the level of PV(O2) by virtue of its location on the oxygen dissociation curve.
Xenon Provides Faster Emergence from Anesthesia than Does Nitrous Oxide-sevoflurane or Nitrous Oxide-isoflurane
Authors: Goto Takahisa , Saito Hayato , Shinkai Masahiro , Nakata Yoshinori , Ichinose Fumito , Morita Shigeho 
Published: November 2003

Background
Xenon, an inert gas with anesthetic properties (minimum alveolar concentration [MAC] = 71%), has an extremely low blood:gas partition coefficient (0.14). Therefore, we predicted that xenon would provide more rapid emergence from anesthesia than does N2O+isoflurane or N2O+sevoflurane of equivalent MAC.

Methods
Thirty American Society of Anesthsiologists class I or II patients undergoing total abdominal hysterectomy were randomly assigned to receive 60% xenon, 60% N2O + 0.5% isoflurane, or 60% N2O + 0.70% sevoflurane (all concentrations are end-tidal: n = 10 per group). After placement of an epidural catheter, anesthesia was induced with standardized doses of midazolam, thiopental, and fentanyl. Thirty minutes later, xenon, N2O+isoflurane, or N2O+sevoflurane was started as previously assigned. These regimens were supplemented with epidural anesthesia with mepivacaine so that the mean arterial pressure and heart rate were controlled within 20% of the preoperative values. At the end of operation lasting approximately 2 h, all inhalational anesthetics were discontinued, and the patients were allowed to awaken while breathing spontaneously on an 8 l/min inflow of oxygen. A blinded investigator recorded the time until the patient opened her eyes on command (T1), was judged ready for extubation (T2), could correctly state her name, her date of birth, and the name of the hospital (T3), and could count backward from 10 to 1 in less than 15 s (T4).

Results
Emergence times from xenon anesthesia were: T1, 3.4 +/- 0.9 min; T2, 3.6 +/- 1 min; T3, 5.2 +/- 1.4 min; and T4, 6.0 +/- 1.6 min (mean +/- SD). These were one half to one third of those from N2O+sevoflurane (T1, 6.0 +/- 1.7 min; T4, 10.5 +/- 2.5 min) or N2O+isoflurane (T1, 7.0 +/- 1.9 min; T4, 14.3 +/- 2.8 min) anesthesia. The three groups did not differ in terms of patient demographics, the duration of anesthesia, the amount of epidural mepivacaine administered, or the postoperative pain rating. No patient could recalls intraoperative events.

Conclusions
Emergence from xenon anesthesia is two or three times faster than that from equal-MAC N2O+isoflurane or N2O+sevoflurane anesthesia.
Alfentanil, but Not Amitriptyline, Reduces Pain, Hyperalgesia, and Allodynia from Intradermal Injection of Capsaicin in Humans
Authors: Eisenach James C. , Hood David D. , Curry Regina , Tong Chuanyao 
Published: November 2003

Background
Intradermal injection of capsaicin produces brief pain followed by hyperalgesia and allodynia in humans, and the latter effects are mediated by spinal N-methyl-D-aspartate mechanisms. Amitriptyline recently was shown to antagonize N-methyl-D-aspartate receptors, and in this study, the authors sought to determine the effect of amitriptyline alone and with the opioid alfentanil on hyperalgesia and allodynia produced by intradermal injection of capsaicin.

Methods
Forty-six healthy volunteers in the general clinical research center received repeated intradermal injections of capsaicin (100 microg) alone or before and after systemic injection of 4 mg midazolam, 25 mg amitriptyline, alfentanil by computer-controlled infusion, or amitriptyline plus alfentanil. Acute pain and areas of mechanical hyperalgesia and allodynia were determined at specified intervals. Blood was obtained for alfentanil and amitriptyline assay.

Results
Capsaicin injection produced acute pain followed by hyperalgesia and allodynia. Alfentanil reduced these pain responses in a plasma-concentration-dependent manner, and reduction in hyperalgesia and allodynia correlated with reduction in acute pain. Amitriptyline alone had no effect and did not potentiate alfentanil. Alfentanil produced concentration-dependent nausea, an effect diminished by amitriptyline.

Discussion
These data correspond with previous studies in volunteers demonstrating reduction in hyperalgesia and allodynia after intradermal injection of capsaicin by systemically administered opioids, and they suggest that this reduction may be secondary to reduced nociceptive input by acute analgesia. These data do not support the use of acute systemic administration of amitriptyline for acute pain, hyperalgesia, and allodynia, although the roles of chronic treatment and spinal administration are being investigated.
Effects of Concentration and Volume of 2-Chloroprocaine on Epidural Anesthesia in Volunteers
Authors: Liu Spencer S. , Ware Paul D. , Rajendran Sundar 
Published: November 2003

Background
Effect of local anesthetic concentration and volume on the spread and density of epidural anesthesia is unclear. This study was performed to delineate effects of a threefold difference in concentration and volume of 2-chloroprocaine on epidural anesthesia.

Methods
Twelve healthy volunteers underwent lumbar epidural anesthesia with 300 mg of 2-chloroprocaine as a 3% (10 ml) and a 1% (30 ml) solution in a randomized, double-blind, balanced, crossover fashion. Sensory block was assessed with pinprick, touch (calibrated plastic filament), cold, and electrical stimulation. Motor block was assessed at the quadriceps and gastrocnemius muscles with isometric force dynamometry. Differences between solutions were assessed with repeated measures analysis of variance followed by post hoc testing.

Results
The number of dermatomes blocked to pinprick, touch, and cold was significantly greater with the 1% concentration (2 dermatomes greater than the 3% concentration on average, P < 0.05). Similar intensity of sensory block to electrical stimulation developed at the hip and knee and was unaffected by concentration of 2-chloroprocaine. Similar intensity of motor block developed at the quadriceps with both concentrations.

Conclusions
Intensity of sensory and motor block from epidural anesthesia with 2-chloroprocaine appears to depend primarily on total milligram dose.