bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of temperature variation (22˚C‐ 44˚C) on halothane and caffeine contracture testing in normal humans
Authors: ANTOGNINI J. F. , GRONERT G. A.
Published: January 2009

Background:Malignant hyperthermia (MH) susceptibility is diagnosed using halothane‐caffeine contracture testing of a muscle sample maintained at 37˚C. However, there has not been a systematic study that examines the effect of different temperatures on the response of normal muscle to halothane and caffeine. We hypothesized that altering bath temperature would modify the contracture responses.

Methods:We obtained muscle samples from 20 patients undergoing surgical procedures of the lower extremities. The samples were dissected into 245 bundles and the bundles were exposed to halothane 3% or incremental caffeine, according to the North American MH group protocol. Several bundles from each patient were simultaneously studied at four different temperatures (22˚C, 30˚C, 37˚C and 44˚C). Each bundle was studied at only one temperature, the muscle samples of 3 patients were simultaneously studied at all four temperatures for halothane and caffeine.

Results:Maximum contracture to caffeine (32 mM) was highest at 37˚C; however, at lower caffeine concentrations (2–4 mM), there was no consistent effect of temperature on contracture response. Likewise, temperature did not alter contracture responses to halothane. The extremes of temperature (22˚C and 44˚C) were associated with lack of twitch in response to electrical stimulation. For the bundles exposed to halothane at 22“C, the absence of a twitch was associated with the presence of a contracture, although these were never above the diagnostic threshold.

Conclusions:We conclude that temperature has little effect on responses of normal muscle to halothane and caffeine.
Intraoperative epidural catheter malfunction in two obese patients
Authors: LEITH P. , SANBORN R. , BROCK‐UTNE J. G.
Published: January 2009

Using a combined general anesthesia/epidural technique, two cases of intraoperative malfunctioning epidural catheters in obese patients are presented. After the epidural was found to be malfunctioning, the anesthesiologist placed the palm of both hands underneath the patients' lumbar and thoracic area. The epidural catheter with tape and subcutaneous tissue was pulled in both cases towards the head. In each case, this simple maneuver made the catheter function again. In conclusion, this simple corrective maneuver should be attempted prior to discarding the epidural anesthetic technique.
Delayed derecruitment after removal of PEEP in patients with acute lung injury
Authors: LICHTWARCK‐ASCHOFF M. , GUTTMANN J. , EBERHARD L. , FABRY B. , BIRLE J. , ADOLPH M.
Published: January 2009

Background:A step decrease in positive end‐expiratory airway pressure (PEEP) is not followed by an instantaneous loss of the PEEP‐induced increase in end‐expiratory lung volume (EELV). Rather, the reduction of EELV is delayed, while adverse PEEP effects on hemodynamics are immediately attenuated upon the drop in airway pressure. Step PEEP increments were applied to the lungs of patients with acute lung injury. It was investigated retrospectively whether enlargement of end‐expiratory lung volume and changes in lung mechanics persist 45 min after removal of the PEEP increment.

Methods: In 14 patients with acute lung injury (LIS score 2.7) EELV and volume‐dependent dynamic compliance of the respiratory system (Cdyn,rs) were determined 45 min after removal of an additional PEEP increment (0.64 kPa added to baseline PEEP of 1.0 kPa).

Results: Nine patients kept an EELV gain of 13% (SD 7) and showed improved Cdyn,rs. In 5 patients, EELV was reduced (by 9% (SD 6)) and Cdyn,rs unchanged after removal of the PEEP increment compared to baseline.

Conclusion: A subgroup of patients with acute lung injury, the characteristics of which remain to be defined, benefit from prolonged recruitment effects up to 45 min after removal of a PEEP increment, while sequelae of continuously increased airway pressures are minimised.
Beneficial effects of the prone position on the incidence of barotrauma in oleic acid‐induced lung injury under continuous positive pressure ventilation
Authors: Du H. L. , YAMADA Y. , ORII R. , SUZUKI S. , SAWAMURA S. , SUWA K. , HANAOKA K.
Published: January 2009

Background: Factors that contribute to ventilator‐induced barotrauma are not well defined. This study investigates the effects of posture on ventilator‐induced barotrauma, as well as arterial oxygenation.

Methods: Twelve dogs with oleic acid lung injury, lying in the prone position (n=6) and right lateral position (n=6), were mechanically ventilated with continuous positive pressure ventilation for 24 hours. The incidence of pneumothorax and arterial oxygenation were investigated in each position. Results: All animals lying in the lateral position developed pneumothorax in the nondependent thorax, while only one animal in the prone position developed pneumothorax in the left thorax (P < 0.05). Postmortem examination revealed that in the lateral group, the nondependent lung consisted of large areas of emphysematous regions and neutrophil infiltration regions, while the dependent lung was composed of extensive atelectasis and neutrophil infiltration. Lung ruptures occurred in the non‐dependent lung at the regions of either emphysematous change or severe neutrophil infiltration. In the prone group, in contrast, both lungs were inflated fairly homogeneously with only small areas of atelectatic and emphysematous changes. In the dog in whom pneumothorax developed, lung ruptures were limited to the regions of severe neutrophil infiltration in the left lung. No animal in either group had a peak airway pressure more than 20 cmH2O. The peak airway pressures were 17.5 ±1.3 cmH2O in the lateral group and 16.6±2.1 cmH2O in the prone group (P>0.05). Tidal volume was comparable between the lateral group (13±2 ml/kg) and the prone group (12±1 ml/kg) before pneumothorax occurred (P>0.05). Arterial oxygenation was much better in the prone group than in the lateral group during the experiment (P < 0.05).

Conclusion:It was concluded that in lung injury dogs, the prone position has beneficial effects on the incidence of ventilator‐induced barotrauma and arterial oxygenation when compared with the lateral position. Ventilator‐induced barotrauma may occur at lower airway pressure.
Results of in vitro contracture tests for the diagnosis of malignant hyperthermia susceptibility in monozygote twins
Authors: ISLANDER G. , TWETMAN E. RANKLEV
Published: January 2009

Background:Malignant hyperthermia susceptibility is a pharmacogenetic disorder in which susceptible individuals may develop a potentially life‐threatening hypermetabolism when exposed to certain anaesthetic agents. The most common diagnostic method is the in vitro contracture test (IVCT) of skeletal muscle biopsies. There is a wide variation in the size of contractures between susceptible individuals and the reproducibility of the test in humans has not been evaluated.

Methods: We have performed the IVCT in 4 monozygote pairs of twins, which gave us on opportunity to study the reproducibility. Results: The clinical diagnoses were consistent in all twin pairs, although slight differences in contractures and thresholds were seen.

Conclusion: In this material the reproducibility of the IVCT was found to be satisfactory.
Grading of severity of postdural puncture headache after 27‐gauge Quincke and Whitacre needles
Authors: CORBEY M. P. , BACH A. B. , LECH K. , FRØRUP A. M.
Published: January 2009

Background: Small‐gauge needles are reported to have a low incidence of complications. Pencil‐point needles are associated with a lower frequency of postdural puncture headache (PDPH), but a higher failure rate than Quincke needles.

Methods: The incidence of PDPH was investigated in 200 patients under the age of 45, undergoing day‐care surgery, after spinal anaesthesia with either 27‐gauge Quincke or Whitacre needle. The severity of headache was graded as I (mild), II (moderate) or III (severe) using a grading system based on the visual analogue scale (VAS) associated with a functional rating (FG).

Results: The frequency of PDPH following the Whitacre needle was 0% and 5.6% after the Quincke needle (P = 0.05). Two PDPHs were assessed as grade III, and three as grade II. All PDPHs occurred when the Quincke needle bevel was withdrawn perpendicular to the dural fibres following parallel insertion. No PDPH occurred when the bevel was inserted and removed parallel to the dural fibres (P < 0.05). There was no statistical difference (P>0.8) in the incidence of PDPH and postdural puncture‐related headaches (PDPR‐H) in patients with recurrent headaches or migraine compared to patients with no previous history of headaches.

Conclusions: We conclude that the 27‐gauge Whitacre needle is the ‘needle of choice’ in patients with normal body stature. The incidence of PDPH following Quincke needles may not only be affected by the direction of the bevel during insertion but also during removal. Statistically, there was no gender variation in PDPH in this study (P=0.5). A previous history of recurrent headache or migraine does not predispose to PDPH.
Subcutaneous emphysema and pneumothorax during laparoscopy for ectopic pregnancy removal
Authors: PERKO G. , FERNANDES A.
Published: January 2009

We report a case of subcutaneous emphysema and pneumothorax during laparoscopic removal of ectopic pregnancy. Increases in airway pressures and end‐tidal carbon dioxide, simultaneously with decrease of lung compliance, led quickly to diagnosis of pneumothorax. We recommend a careful monitoring of these variables during laparoscopic procedures. Carbon dioxide pneumothorax can occur even without pulmonary or pleural trauma.
Calculated versus measured oxygen consumption during and after cardiac surgery. Is it possible to estimate lung oxygen consumption?
Authors: KEINÄNEN O. , TAKALA J.
Published: January 2009

Background: Lung tissue is metabolically active and consumes oxygen. The oxygen content difference between arterial and mixed venous blood does not include the effect of pulmonary tissue oxygen uptake. Thus, oxygen consumption (VO2) of the lung should be reflected as a difference between VO2 measured by gas exchange and VO2 derived by the Fick principle. The purpose of this study was to measure in clinical conditions this difference (taken to represent the VO2 of the lung), and to evaluate the sources of error in lung VO2 estimation.

Methods: Nine patients undergoing coronary artery bypass grafting were studied. VO2 was measured by indirect calorimetry (VO2gasex) and compared to Fick‐derived VO2 (VO2Fick) after induction of anaesthesia, after closure of the chest, at admission to intensive care, after stabilization of haemodynamics and during weaning from mechanical ventilation. The Fick‐derived VO2 was calculated from blood samples taken at the beginning and at the end of each 20 min measurement period, and the mean of 12 consecutive thermodilution cardiac output measurements taken during each 20 min measurement period.

Results: VO2gasex was higher than VO2Fick (P <0.01; in all except 4 of 45 measurements). The difference between the measured and the calculated VO2 was 33 ±25 ml/min (mean±SD, range ‐16–100 ml/min). This difference represented 14±3% (range 11–18%) of the whole body VO2. The VO2‐difference was highest after the induction of anaesthesia (50±19 ml/min; range 20–81 ml/min, P < 0.03) and lowest on arrival at the intensive care unit (10±16 ml/min; range ‐16–39 ml/min). Core temperature did not correlate with the oxygen consumption difference.

Conclusions: A constant difference between measured and calculated VO2 can be detected in carefully controlled clinical conditions. The difference between the two methods is due to both lung oxygen consumption and errors in the measurement of VO2, thermodilution cardiac output, haemoglobin and blood oxygen contents. We suggest that the perioperative changes of the VO2‐difference are due not only to variation of the measurements but also to changes in lung metabolic activity.
Relationship between intra‐ and postoperative oxygen transport and prolonged intensive care after cardiac surgery: a prospective study
Authors: PÖLÖNEN P. , HIPPELÄINEN M. , TAKALA R. , RUOKONEN E. , TAKALA J.
Published: January 2009

Background: Prolonged intensive care is a rare but serious complication of cardiac surgery. It is required in less than 10% of operated patients but they use more than 30% of all the intensive care resources needed for cardiac surgery. The aim of our study was to describe the clinical course of the patients who need prolonged intensive care following cardiac surgery and to assess whether the intra‐ and postoperative oxygen transport variables are different in these patients as compared to patients with an uncomplicated course.

Methods: The study patients were divided into two groups according to the length of stay in the intensive care unit (ICU) after the operation: Group I, n=241, ICU‐stay 5 days and Group II, n=20, ICU‐stay≥5 days. Hemodynamic and oxygen transport data were prospectively obtained intra‐ and postoperatively and postoperative organ dysfunctions were recorded.

Results: The patients in the prolonged intensive care group tended to be older, have lower ejection fraction and longer cardiopulmonary bypass time. Postoperatively, this group had significantly increased oxygen extraction rate (P=0.035, repeated measures for ANOVA). In the logistic regression analysis, in creased oxygen extraction (31% in Group I vs. 36% in Group II, P < 0.005) at 6 hours after arrival at the intensive care unit had the strongest independent association with the need for prolonged intensive care.

Conclusions: There was no significant relationship between the factors conventionally assumed to be risk factors for prolonged intensive care. Instead, an increase in whole body oygen extraction, reflecting a mismatch between the whole body oxygen demand and supply, was associated with the need for prolonged intensive care. Oxygen extraction increased to compensate for the reduced oxygen delivery, which in turn was caused by a lower arterial oxygen content.
Hemodynamic and coronary vascular effects of dexmedetomidine in the anesthetized goat
Authors: LAWRENCE C. J. , PRINZEN F. W. , LANGE S. DE
Published: January 2009

Background:In phase III trials, the hemodynamic stabilising effect of the α2‐adrenergic agonist dexmedetomidine (DEX) is being investigated in patients with coronary artery disease. Coronary vascular effects of α2‐agonists have been studied in dogs and pigs, but both species have a different hemodynamic response to DEX than man. The aim of this study was to investigate the hemodynamic and coronary vascular effects in goats.

Methods:In 6 open‐chest goats anesthetized with halothane, central and coronary hemodynamics and oxygen supply and demand were measured before and following IV bolus infusion of DEX in doses ranging from 0.1 to 10 μg/kg.

Results:With DEX doses of 1 μg/kg or higher, mean arterial pressure (MAP), systemic vascular resistance, coronary vascular resistance and arterio‐mixed venous oxygen content increased within 2 min, but returned to baseline within 15 min. In contrast, there was a progressive and cumulative decrease in cardiac output (CO), heart rate, and dP/dtmax. Regional coronary venous oxygen extraction (C(a‐cv)O2) transiently increased after 3 μg/kg DEX and decreased 15 min after 10 μg/kg DEX. LVEDP transiently increased after 3 and 10 μg/kg DEX. The changes after DEX 10 μg/kg differed from those after lower doses: MAP (35%), CO (50%), stroke volume (33%), C(a‐cv)O2(15%) and myocardial oxygen extraction (33%) were all decreased. Myocardial oxygen supply and demand decreased in parallel.

Conclusions:1) The cardiovascular response to IV DEX in goats is similar to man. 2) In goats after DEX, systemic and coronary vasoconstriction are short‐lived, and 3) the balance between myocardial oxygen supply and demand is maintained.
Role of zatebradine and propranolol in attenuation of tachycardia produced by dobutamine in pigs
Authors: NEUSTEIN S. M. , DIMICH I. , SHIANG H. , MEZROW C.
Published: January 2009

Background:Zatebradine is a new specific bradycardic agent that selectively slows the depolarization in the pacemaker cells of the sinoatrial node. The purpose of our investigation was to determine whether the tachycardia induced by dobutamine can be attenuated by the administration of zatebradine. The results were compared with those produced by propranolol, which is used in the treatment of sinus tachycardia.

Methods:Twelve pigs were anesthetized with sodium pentobarbital, intubated, and ventilated. After baseline hemodynamic measurements were obtained, dobutamine was administered until the heart rate reached 25% above baseline. Animals were randomized to one of two groups. Group I received zatebradine, 0.5 mg/kg IV, and Group II received propranolol, 0.5 mg/kg IV.

Results:Dobutamine 10 μg kg‐1min‐1increased the heart rate (HR) by 25%, and increased mean arterial blood pressure (MAP), left ventricular (LV) dP/dt, and cardiac output (CO) (P< 0.05). Zatebradine decreased the HR to baseline (P< 0.05) without affecting left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), LV dP/dt, or CO. Stroke volume (SV) increased significantly (P< 0.05). Propranolol also reduced HR to baseline, but decreased LV dP/dt, LVSP, CO, and SV (P< 0.05).

Conclusion:Zatebradine effectively attenuates the tachycardia caused by dobutamine in anesthetized pigs, without reducing cardiac performance.
Analgesic and psychomotor effects of thiopental at subanesthetic concentrations in human volunteers
Authors: YOUNG C. J. , COALSON D. , KLOCK P. A. , KLAFTA J. M. , GOLDSHER G. , APFELBAUM J. L. , ZACNY J. P.
Published: January 2009

Background:Studies of the effects of barbiturates on the modulation of pain have produced mixed results. In a prospective, double‐blind, randomized, placebo‐controlled trial, we studied the effects of thiopental at presumed steady‐state, “conscious sedation” levels on cold‐pressor‐induced pain in 12 healthy volunteers.

Methods:Five drug conditions were used, each condition consisting of an injection (either drug or placebo) with a 20‐min infusion and a 160‐min recovery period. The conditions were placebo (saline), thiopental targeted to three effect‐site concentrations, and fentanyl (1.4 μg/kg), as a positive control to verify test sensitivity to analgesic drugs. The three thiopental concentrations were modeled (STANPUMP) to achieve effect‐site concentrations of 5, 7.5, and 10 μg/ml using a bolus and a three‐step continuous infusion. Five minutes into the infusion period and 115 min after the infusion period was terminated, subjects immersed their forearms in ice cold water for 3 min while pain and behavioral assessments were recorded.

Results:Thiopental at the highest dose produced a significant reduction (P< 0.05) in self‐reported pain intensity both at 5 min into the infusion period and at 115 min after termination of the infusion. Fentanyl reduced pain intensity during the first immersion only. Thiopental changed subjects' moods and psychomotor performance in a dose‐related fashion.

Conclusions:Our laboratory results do not support the long‐held belief that barbiturates are “antanalgesic” or hyperalgesic, at least for cold‐pressor‐induced pain.
In vitro contracture test for diagnosis of malignant hyperthermia following the protocol of the European MH Group: Results of testing patients surviving fulminant MH and unrelated low‐risk subjects
Authors: ØRDING H. , BRANCADORO V. , COZZOLINO S. , ELLIS F. R. , GLAUBER V. , GONANO E. F. , HALSALL P. J. , HARTUNG E. , HEFFRON J. J. A. , HEYTENS L. , KOZAK‐RIBBENS G. , KRESS H. , KRTVOSIC‐HORBER R. , LEHMANN‐HORN F. , MORTIER W. , NIVOCHE Y. , RANKLEV‐TWETMAN E. , SIGURDSSON S. , SNOECK M. , STIEGLITZ P. , TEGAZZIN V. , URWYLER A. , WAPPLER F.
Published: January 2009

Background: Determination of sensitivity and specificity of the in vitro contracture test (IVCT) for malignant hyperthermia (MH) susceptibility using the European MH Group (EMHG) protocol has been performed in some laboratories but only on a small sample from the combined EMHG. Thus, the purpose of the present study was to determine combined EMHG sensitivity and specificity of the test.

Methods: Results of IVCT of patients with previous fulminant MH and normal, low‐risk subjects (controls) were collected from 22 centresof the EMHG. IVCT was performed according to the EMHG protocol. Patients were included inthe study if the clinical crisis had a score of at least 50 points with the Clinical Grading Scale. Low‐risk subjects were included provided they did not belong to a family with known MH susceptibility, they had not developed any signs of MH at previous anaesthetics, and they did not suffer from any neuromuscular disease. For inclusion of both MH patientsand low‐risk subjects, at least 1 muscle bundle in the IVCT should have twitches of 10 mN(1 g) or more. For evaluation of individual tests, only muscle bundles with twitch heights of 10 mN (1 g) or more were used.

Results: A total of 1502 probands had undergone IVCT because of a previous anaesthesia with symptoms and signs suggestive of MH. Of these, 119 had clinical scores of 50 and above. From these 119 MH‐suspected patients and from 202 low‐risk subjects, IVCT data were collected. Subsequently, 14 MH‐suspected patients were excluded from further analysis for thefollowing reasons: In 3 patients, the suspected MH episode could be fully explained by diseases other than MH; in 11 MHS patients, IVCT was incomplete (n=l), data were lost (n=3), or none of the muscle bundles fulfilled twitch criteria (n=7). Of the remaining 105 MH‐suspected patients, 89 were MHS, 10 MHEh, 5 MHEc, and one MHN. Thus, we observed a diagnostic sensitivity of the IVCT of 99.0% if the MHE group is considered susceptible(95% confidence interval 94.8–100.0%). Of the 202 low‐risk subjects, 3 were MHS, 5 MHEh, 5 MHEc, and 189 MHN. This gives a specificity of the IVCT of 93.6% (95% confidence interval 89.2–96.5%).

Conclusion: The IVCT for diagnosis of MH susceptibility in Europe has a high sensitivity and a satisfactory specificity.
4‐chloro‐m‐cresol test ‐ a possible supplementary test for diagnosis of malignant hyperthermia susceptibility
Authors: ØRDING H. , GLAHN K. , GARDI T. , FAGERLUND T. , BENDIXEN D.
Published: January 2009

Background: In vitro contracture test (IVCT) for diagnosis of MH in our laboratory has a sensitivity of 100% and a specificity of 93%. The results are equivocal in 10–15%, and supplementary tests may thus be required. We have tested the hypothesis that 4‐chloro‐m‐cresol (4‐cmc) may be useful for a supplementary test.

Methods: Muscle from 41 consecutive patients from 7 families undergoing diagnostic muscle biopsy with IVCT was exposed in vitro to increasing concentrations of 4‐cmc (25, 50, 75, 100, 150, and 200 umol 1‐‐1), and the force development recorded. Diagnosis of MH susceptibility was made with standard halothane and caffeine tests and included as results MHS (MH susceptible), MHN (MH negative), and MHE (equivoval result).

Results: At all concentrations of 4‐cmc, the increase in baseline force was significantly greater in the MHS group compared to the MHN group (P < 0.05). Muscle from 15 MH‐susceptible (MHS) patients responded to 4‐cmc with increasing force at a threshold concentration of 75 umol 1‐‐1 or less, whereas muscle from 23 MH‐non‐susceptible (MHN) patients had thresholds of 100 umol 1‐‐1 or more. The accuracy of the chlorocresol test was thus 100% (95% confidence limits 90.75–100%) at a threshold of 75 umol 1‐‐1. Amplitude of contractures at 2 mmol 1‐‐1 caffeine was not different from contractures at 75 umol 1‐‐1 of 4‐ cmc in either the MHS or the MHN group (P > 0.05). In vivo concentrations of chlorocresol from clinical use of insulin and somatro‐pin are estimated to be 20 times less than the threshold concentration and thus these drugs seem safe in MH patients.

Conclusion: 4‐chloro‐m‐cresol may be a suitable aid to clarify puzzling results of standard testing of MH susceptibility.
Incidence of awareness in total i.v. anaesthesia based on propofol, alfentanil and neuromuscular blockade
Authors: NORDSTRÖM O. , ENGSTRÖM A. M. , PERSSON S. , SANDIN R.
Published: January 2009

Background: There is no reliable technique for monitoring drug concentrations in totali.v. anaesthesia (TIVA) with muscle relaxation. An increased risk of awareness with TIVAhas been stated as a possible drawback (1, 2). The present study was conducted in order toassess the incidence of conscious awareness in TTVA based on propofol, alfentanil and neuromuscular blockade.

Methods: One thousand patients anaesthetized with TIVA based on propofol, alfentanil, and neuromuscular blockade were subjected postoperatively to a structured interview for conscious awareness on two separate occasions: on discharge from the post‐anaesthesia care unit, and the day after anaesthesia. Five hundred of these patientswere also interviewed a third time, approximately 1 week later.

Results: Two cases of awareness were detected (0.2%). One of these was identified immediately after extubation. The second patient had no memory of intraoperative events or dreams at the first interview, recalled a bad dream on the day after, and had explicit recall of intraoperative events at the interview 8 days later. In both cases, haemodynamic signs of inadequate anaesthesia were present. The incidence of conscious awareness in this study is similar to the lowest previously reported incidence of awareness following general anaesthesia in patientswho had been paralyzed and thereafter subjected to a structured postanesthesia interview.

Conclusions: If the true incidence of conscious awareness is to be determined, interviewsmust be extended beyond the first postoperative day. Our study indicates that if appropriate dosing of propofol and alfentanil are adhered to, and proper action is taken in case of haemodynamic alterations suggestive of inadequate anaesthesia, the incidence of conscious awareness in non‐cardiac TIVA with neuromuscular blockade is low.
Cerebral normoxia in the rhesus monkey during isofluraneor propofol‐induced hypotension and hypocapnia, despite disparate blood‐flow patterns
Authors: ENLUND M. , ANDERSSON J. , HARTVIG P. , VALTYSSON J. , WIKLUND L.
Published: January 2009

Background: Due to a few reports of cerebral dysfunction in connection with isoflurane‐induced hypotension and concomitant hypocapnia, positron emission tomography (PET) was used to measure cerebral oxygenation and blood flow during similar conditions with isoflurane or propofol.

Methods: The short‐lived radionuclide 15O was used for measurement of cerebralmetabolic rate of oxygen (CMRO2), cerebral blood flow (CBF) and oxygen extraction ratio (OER) regionally in rhesus monkeys during normotensive/normocapnic and hypotensive/hypocapnic conditions, mean arterial pressure 100–110 and 50–65 mmHg and PaCO2 4.4–5.4 and 3.4‐4.4 kPa, respectively. Isoflurane or propofol anaesthesia was given (n=4 in both groups), supported with 70% nitrous oxide and preceded by ketamine anaesthesia (baseline).

Results: PET revealed wide variations in CBF between regions during isoflurane anaesthesia, particularly in comparison with propofol anaesthesia, while rCMRO2 decreased globally in a dose‐dependent manner during both isoflurane and propofol anaesthesia. The metabolism‐flow coupling was intact during propofol but not during isoflurane anaesthesia. Hypotension reduced rCBF, and rOER increased globally with both study drugs when changing from normo‐ to hypotension. However, this rOER increase was not significant when using PaCO2 as a co‐variate, and rOER was never above an arbitrary limit for hypoxia of 70%. Thus, hypocapnia, rather than hypotension, was responsible for the somewhat higher rOER measured.

Conclusion: PET indicated adequate cerebral oxygenation during isoflurane and propofol anaesthesia, despite disparate blood‐flow patterns. Hypotension and concomitant moderate hyperventilation reduced rCBF, but did not result in hypoxia.
Neurohistopathological findings after continuous intrathecal administration of morphine or a morphine/ bupivacaine mixture in cancer pain patients
Authors: WAGEMANS M. F. M. , VAN DER VALK P. , SPOELDER E. M. , ZUURMOND W. W. A. , LANGE J. J. DE
Published: January 2009

Background: As the number of terminal cancer patients receiving continuous intrathecalinfusion of opioids and local anesthetics for relief of pain increases, we decided to investigate the post‐mortem findings of the spinal cord, meninges and nerve roots of patients after continuous intrathecal administration of morphine and combined with bupivacaine.

Methods: Neurohistopathological findings were obtained from 10 cancer patients [2 men and 8 women, 29–69 (median 52) yrs old] and 4 controls [4 men, 46–75 (median 64) yrs old]. The cancer patients had been treated for a mean of 98 (range 8–452) d with morphine/NaCl 0.9% or morphine/bupivacaine, administered through a polyamide lumbar catheter. Concomitant radiation therapy and chemotherapeutic drug had been given to 5 and 6 patients, respectively. Cumulative doses of morphine ranged from 22 to 3895 mg, those of bupivacaine from 0 to 3250 mg and of sodium metabisulfite (antioxidant) from 0.6 to 97.4 mg.

Results: No macroscopic abnormalities of the catheter tract, dura, leptomeninges, nerve roots or spinal cord were found. Microscopically, focal foreign body giant cells were seenin 2 cases in the area of the catheter pathway both without any sign of inflammation. In one case treated for 103 d, an intrathecal reaction was found. This consisted of small aggregates of lymphocytes predominantly in the leptomeninges and focally in the cord parenchyma. No abnormalities were found in the other cases when using hematoxylin‐eosin and Kluver or Bodian stained specimens, indicating neither myelin nor axonal damage. Microglial reactions were similar in both cancer patients and controls.

Conclusion: The discrete and limited neurohistopathological findings in both catheter patients and controls suggest that intrathecal infusion of morphine and bupivacaine via a polyamide catheter is devoid of significant neurotoxic effects in cancer patients.
Suppression of acetylcholine‐induced relaxation by local anesthetics and vascular NO‐cyclic GMP system
Authors: MINAMOTO Y. , NAKAMURA K. , TODA H. , MIYAWAKI I. , KITAMURA R. , VINH V. H. , HATANO Y. , MORI K.
Published: January 2009

Background:Local anesthetics have been demonstrated to attenuate acetylcholine‐induced relaxation of vascular smooth muscle, but the mechanism responsible has not been elucidated. The present study was undertaken to ascertain whether this effect of local anesthetics is due to suppression of the vascular nitric oxide (NO)‐cyclic GMP (cGMP) system.

Methods:Isolated rat aortae were cut into helical strips and mounted in bathing solution to measure isometric tension changes. They were precontracted with phenylephrine (0.3 μM)then exposed to cumulative concentrations of relaxants including acetylcholine, sodium nitroprusside (SNP) and papaverine, in the absence or presence of local anesthetics. Aortaefor cGMP measurements were cut longitudinally into pairs of strips and bathed in the solution without tension. In the absence or presence of anesthetics, they were stimulated with acetylcholine or SNP, and the cGMP content of each strip was radioimmunoassayed.

Results:Acetylcholine‐induced, endothelium‐dependent relaxation of phenylephrine‐precontracted aortae was attenuated by lidocaine (30–300 μM), tetracaine (10–30 μM), bupivacaine (10–100 μM) and ropivacaine (30–100 μM). SNP‐inducedrelaxation was attenuated by lidocaine (300 μM), tetracaine (30 μM), bupivacaine (10–100 μM) and ropivacaine (30–100 μM). Papaver‐ine‐induced relaxation was attenuated by lidocaine (300 μM), bupivacaine (30–100 μM) and ropivacaine(30–100 μM), and augmented by tetracaine (30 μM). Cyclic GMP levels in acetylcho‐line‐stimulated aortae were reduced significantly by lidocaine (300 μM), tetracaine(100 μM) and bupivacaine (300 μM) treatment, but not by ropivacaine (300 μM). SNP‐stimulated cGMP levels were reduced by tetracaine (100 μM) but not by any other anesthetics at the concentrations tested.

Conclusion:We conclude that lidocaine, tetracaine and bupivacaine suppress acetylcholme‐stimulated formation of cGMP. However, the attenuation of acetylcholine‐induced relaxation by local anesthetics is not totally ascribable to reduced cGMP levels.
Analgesia after upper abdominal surgery using extradural administration of a fixed dose of buprenorphine in combination with lignocaine given at two infusion rates: A comparative study
Authors: WAJIMA Z. , SHITARA T. , ISHIKAWA G. , KANEKO K. , INOUE T. , OGAWA R.
Published: January 2009

Background: Extradural administration of combinations of local anaesthetics and opioids are frequently employed for postoperative pain relief. There is a scarcity of data on the analgesic effects of variations of the dose of local anaesthetic drug admixed to a fixed dose of opioid.

Methods: Twenty‐four patients were investigated after elective upper abdominal surgery. During closure of the abdomen, 2% mepivacaine (8 ml) with buprenorphine 0.1 mg (0.5 ml) was given extradurally. After extubation, patients were randomly allocated to receive continuous extradural infusion of a fixed dose of buprenorphine (0.017 mg/h) in combination with 2% lignocaine at either 2.1 ml/h (low rate group, n = 14) or 6.3 ml/h (high rate group, n = 10). Postoperative pain at rest was assessed using visual analogue scale (VAS) scores and pain at movement by Prince Henry Pain Scale (PHPS)scores. Venous plasma lignocaine concentrations were measured.

Results: VAS scores at rest were similar in the two groups at 3 h postoperatively, whereas at 6–24 h postoperatively, VAS scores were higher in the low rate group than in the high rate group. PHPS scores were similar in the two groups at 3 h and at 18 h postoperatively, whereas at 6, 9, 12 and 24 h postoperatively, PHPS scores were higher in the low rate group than in the high rate group. Plasma lignocaine concentrations were higher at23 h postoperatively in the high rate group than at 16 h in both groups, and at 23 h in the low rate group. At 3 h postoperatively, both the systolic and diastolic arterial pressures were higher in the low rate group than control values obtained on admission. Side effects were observed in one patient in the low rate group who complained of dizziness, andin one patient in the high rate group who complained of nausea.

Conclusions: When added to a fixed dose of buprenorphine, continuous extradural infusion of 2% lignocaine at high rate provides better postoperative analgesia than when given at low rate without producing significant side effects.
Two cases of fatal air embolism in children undergoing scoliosis surgery
Authors: SUTHERLAND R. W. , WINTER R. J.
Published: January 2009

Venous air embolism during surgery is a rare but important complication and can be rapidly fatal. We present two cases of fatal air embolism in the prone position occurring in small children undergoing surgery for progressive scoliosis.

Venous air embolism is a rare complication in the prone position. This is thought to be because in this position there is virtually no gravitational gradient between the site of surgery and the right atrium.

The possible sites of entry of air and ways that this may be minimized are discussed.
Blockade of endogenous nitric oxide production results in moderate hypertension, reducing sympathetic activity and shortening bleeding time in healthy volunteers
Authors: ALBERT J. , SCHEDIN U. , LMDQVIST M. , MELCHER A. , HJEMDAHL P. , FROSTELL C.
Published: January 2009

Background: Short‐term infusion of NG‐monomethyl‐L‐arginine (L‐NMMA) reversibly inhibits endogenous nitric oxide (NO) production in humans. We studied responses to more long‐lasting (60 min) infusions, at doses high enough to cause effective inhibition of endogenous NO.

Results: L‐NMMA significantly elevated mean arterial pressure by 123%, due to an increase in systemic vascular resistance. Cardiac output decreased by 233%, due to a decrease in stroke volume. Pulmonary vascular resistance (P < 0.05) increased, but mean pulmonary arterial pressure was stable. Forearm vascular resistance (P < 0.05) decreased. Bleeding time was shortened by 31 4% (P < 0.01). L‐NMMA infusion reduced NO concentrations in nasal air by 6422% (RO.01). Arterial pressure remained elevated and nasal NO remained depressed 90 min after the infusion, whereas most other responses were reversed at that time. Plasma cGMP showed only minor changes. Plasma norepinephrine decreased, suggesting reflexogenic inhibition of sympathetic activity, whereas epinephrine levels were low and stable throughout the experiment.

Conclusion: Dosage of (13.5 mg · kg‐1 in 60 min) L‐NMMA infusion in humans was well tolerated. Pronounced and long‐lasting inhibition of endogenous NO production, as evidenced by measurements in nasal air, resulted in unevenly distributed vasoconstriction, a transient decrease in cardiac output, and reflexogenic sympathetic withdrawal. Furthermore, bleeding time was shortened, suggesting platelet activation.

Methods: Eight healthy volunteers had catheters (pulmonary, arterial and venous) placed. Measurements included hemodynamics, endogenous NO levels in nasal air, bleeding time, and cyclic guanosine monophosphate (cGMP) and catecholamines in plasma. L‐NMMA was infused at 0.3 mg · kg‐l · min‐1 during 30 min, followed by 0.15 (n=6) or 0.3 (n=2) mg · kg‐1 · min‐1 during 30 min.
Effect of thoracic epidural anaesthesia on ventilation= perfusion distribution and intrathoracic blood volume before and after induction of general anaesthesia
Authors: HACHENBERG T. , HOLST D. , EBEL C. , PFEIFFER B. , THOMAS H. , WENDT M. , HEDENSTIERNA G.
Published: January 2009

Background: Gas exchange is impaired during general anaesthesia due to development of shunt and ventilation‐perfusion mismatching. Thoracic epidural anaesthesia (TEA) may affect the mechanics of the respiratory system, intrathoracic blood volume and possibly ventilation‐perfusion (VA/Q) distribution during general anaesthesia.

Methods: VA/Q relationships were analyzed in 24 patients undergoing major abdominal surgery. Intrapulmonary shunt (Qs/ QT), perfusion of “low” VA/Q areas, ventilation of “high VA/ regions, dead space ventilation and mean distribution of ventilation and perfusion were calculated from the retention/excretion data of six inert gases. Intrathoracic blood volume (ITBV) and pulmonary blood volume (PBV) were determined with a double indicator technique. Recordings were made before and after administration of 8.5±1.5 ml bupivacaine 0.5% (n=12) or 8.3±1.8 ml placebo (n=12) into a thoracic epidural catheter and after induction of general anaesthesia.

Results: Before TEA, QS/QT was normal in the bupivacaine group (222%) and the placebo group (23%). TEA covering the dermatomal segments T 12 to T 4 had no effect on VA/Q relationships, ITBV and PBV. After induction of general anaesthesia S/T increased to 84% (bupivacaine group, P < 0.05) and to 72% (placebo group, P < 0.05). ITBV and PBV decreased significantly to the same extent in the bupivacaine group and the placebo group.

Conclusions: TEA has no effect on VA/Q distribution, gas exchange and intrathoracic blood volume in the awake state and does not influence development of S/T and VA/Q inequality after induction of general anaesthesia.
Ropivacaine 7.5 mg/ml for elective Caesarean section. A clinical and pharmacokinetic comparison of 150 mg and 187.5 mg
Authors: IRESTEDT L. , EMANUELSSON B‐M. , EKBLOM A. , OLOFSSON C. , REVENTLID H.
Published: January 2009

Background: The new, long‐acting local anaesthetic ropivacaine has shown less systemic toxicity than bupivacaine and a concentration of 7.5 mg/ml can therefore be used for epidural anaesthesia in Caesarean section. The present pilot study was undertaken to find indications for an optimal dosage by comparing the clinical effects, quality of anaesthesia and pharmacokinetics of ropivacaine 150 mg (lower dose=LD) vs 187.5 mg (higher dose=HD) for women undergoing elective Caesarean section under epidural anaesthesia.

Methods: Sixteen full‐term women scheduled for elective Caesarean section in two equal‐sized consecutive groups received 20 or 25 ml ropivacaine epidurally in this non‐randomised, open study. Study parameters included sensory and motor blockade, circulatory response, intraoperative pain and discomfort, neonatal evaluation and pharmacokinetic determinations.

Results: Block height varied between T5 and T2 in the LD group, whereas the HD group produced 4 unnecessarily high blocks (C8 in 3 women and C7 in 1 woman). Surgical anaesthesia was excellent in both groups. Circulatory stability was pronounced in the LD group (no ephedrine given), while 4 women required ephedrine in the HD group. Neonatal outcome as judged by Apgar scores, umbilical blood gas determinations and NACS scores were excellent in both groups. The plasma concentration‐time profiles indicated linearity in the concentration range studied, with similar clearance values to those reported previously. Pla‐cental drug equilibrium was rapid; however, the foetal drug exposure depended on intrauterine exposure time.

Conclusions: 20–25 ml ropivacaine 7.5 mg/ml produced very satisfactory conditions for elective Caesarean section under epidural anaesthesia. In this small population, 150 mg ropivacaine seemed optimal, while 187.5 mg produced unnecessarily extended block height in 50% of the women.
Desflurane increases brain tissue oxygenation and pH
Authors: HOFFMAN W. E. , CHARBEL F. T. , EDELMAN G.
Published: January 2009

Background Desflurane anesthesia can produce cerebral metabolic depression and increase cerebral blood flow. We evaluated the effect of desflurane on brain tissue oxygen pressure (PO2), carbon dioxide pressure (PCO2) and pH during neurosurgery.

Methods: Following a craniotomy, the dura was opened and a Paratrend 7 sensor, which measures PO2, PCO2, pH and temperature, was inserted into brain tissue. In 6 control patients in group 1, anesthesia was maintained constant with 3% end‐tidal desflurane over 60 min, including a 30‐min stabilization period. In group 2, 9 patients were ventilated with 3% desflurane under baseline conditions. After a 30‐min stabilization period, baseline tissue gases and pH were measured and end‐tidal desflurane was increased to 6% and then 9% for 15‐min intervals. Mean arterial pressure (MAP) was maintained with intravenous phen‐ylephrine.

Results: Under baseline conditions, cardiovascular and brain tissue measures were similar between the 2 groups. Increasing end‐tidal desflurane from 3% to 9% produced burst‐suppression EEG in all patients and significantly increased tissue PO2 and pH and decreased PCO2. No parameters changed significantly in the control group during steady‐state anesthesia.

Conclusion: These results show that 9% desflurane can improve brain tissue metabolic status before temporary brain artery occlusion if cerebral perfusion pressure is maintained. This may be particularly important in patients with symptoms of ischemia before surgery.
Effective dose of granisetron in the reduction of nausea and vomiting after breast surgery
Authors: FLJJII Y. , TANAKA H. , TOYOOKA H.
Published: January 2009

Background: Prophylactic use of granisetron, a selective Shydroxytryptamine type 3 receptor antagonist, reduces the incidence of nausea and vomiting after breast surgery. This study was undertaken to determine the minimum effective dose of granisetron in the reduction of postoperative nausea and vomiting (PONV) in patients undergoing general anaesthesia for breast surgery.

Methods: In a randomized, double‐blind manner, 120 female patients aged 42–66 years were assigned to receive either placebo (saline) or granisetron in a dose of 20 μg · kg‐1, 40 μg · kg‐1 and 80 μg · kg‐1 i.v. immediately before the induction of anaesthesia. A standard general anaesthetic technique was employed throughout. The POW and safety assessments were performed continuously during the first 24 h after anaesthesia.

Results: There were no significant differences among the groups with regard to patient demographics, surgical procedures, anaesthetics administered and analgesics given. The incidence of PONV was 47%, 43%, 17% and 17% after administration of placebo and granisetron 20 μg ‐kg‐1, 40 μg kg‐1 and 80 μg kg‐1, respectively. Granisetron 40 μg kg‐1 was as effective as 80 μg ‐ kg‐1 and both resulted in significant reductions of the incidence of PONV compared with placebo and granisetron 20 μg kg‐1 (P < 0.05). No differences in the incidence of adverse events were observed among the groups.

Conclusion: Granisetron 40 μg · kg‐1 appears to be the minimum effective dose for reducing POW in patients undergoing general anaesthesia for breast surgery.
Eltanolone for induction of anaesthesia in the surgical patient A comparison of dose requirements in young and elderly patients
Authors: SEAR J. W.
Published: January 2009

Background The relative potency of the steroid anaesthetic agent eltanolone has been compared with respect to induction of anaesthesia in ASA I and II young (1840: years) and elderly (>65 years) patients.

Results: Anaesthesia was adequately induced in 12/40 elderly and 7/40 young patients. The lowest effective induction dose was 0.2 mg/kg in elderly and 0.3 mg/kg in young patients. This gave a relative potency of 0.28 (95% CI 0.12–52; P=0.0039). The cardiovascular effects associated with induction were small; other side‐effects included involuntary movement and hypertonus, and respiratory upsets (apnoea, hiccups and coughing).

Conclusion: The effective induction dose of eltanolone was significantly lower in the elderly patients; but the drug safety profile was similar in both age groups of patients.

Method:113 temazepam premedicated patients (60 elderly) were evaluated in an open randomised study. They were allocated to receive doses between 0.05 and 0.75 mg/kg given i.v. over 30 s. The first 33 patients formed a pilot phase; the formal study comprised 80 patients. The primary efficacy variable was loss of verbal contact within 120 s and an effect lasting more than 4 min. All patients breathed 100% oxygen throughout the study period. Safety data (heart rate, blood pressure, respiratory apnoea, involuntary movements, hypertonus and other adverse effects) were noted.
The effects of cardiac surgery on early and late pulmonary functions
Authors: SHENKMAN Z. , SHIR Y. , WEISS Y. G. , BLEIBERG B. , GROSS D.
Published: January 2009

Background: Impaired pulmonary functions are common in cardiac patients. Early and late effects of cardiac surgery on pulmonary function tests (PFTs) are presented.

Methods: Fifty patients undergoing cardiac surgery (coronary artery bypass grafting [CABG, 74%], valve replacement or val‐vuloplasty [20%] and combined procedures [6%]) were studied. Anginal and cardiac failure symptoms severity, and smoking history, were evaluated preoperatively. PETS were studied and compared pre‐, and 3 weeks and 3.5 months postoperatively.

Results: Pre‐ and postoperative PFTs were inversely related to severity of preoperative symptoms. Forced vital capacity (FVC) dropped from 98% of predicted preoperatively, to 63% (P < 0.00001) and 75% (P < 0.0001) 3 weeks and 3.5 months postoperatively, respectively. Expiratory volume in the first 1 s of forced expiration (FEW.O) decreased from 95% to 61% (P < 0.00001) and 70% (P < 0.00001), respectively. Forced expiratory flow at 50% of vital capacity (FEF50) decreased from 85% to 56% (P < 0.00001) and 59% (P < 0.00001). Forced expiratory flow at 75% of vital capacity (FEF75) decreased from 77% to 47% and 47% (P < 0.00001). Peak expiratory flow rate (PEFR) declined from 101% to 66% (P < 0.00001) and 86% (P < 0.003). Maximal voluntary ventilation declined from 103% to 68% (P < 0.00001) and 77% (P < 0.00001). Only FVC (P < 0.0003), FEV1.0 (P < 0.02) and PEFR (P < 0.00001) partially recovered postoperatively. Smoking history did not affect perioperative PETS. Pre‐, but not postoperative FVC, FEV1.0, FEF50 and FEF75 were worse in valve than in CABG patients.

Conclusions: Pulmonary functions deteriorate significantly for at least 3.5 months after cardiac surgery. Preoperative cardiac ischaemic and failure symptoms are inversely related to perioperative PETS.