bluuebunny/crossref_metadata_2025 huggingface dataset:
Expiratory flow‐volume curves in mechanically ventilated patients with chronic obstructive pulmonary disease
Authors: Aerts J. G. J. V. , Van Den Berg B. , Lourens M. S. , Bogaard J. M.
Published: March 2003

Background: Forced expiratory flow‐volume curves are commonly used to assess the degree of airflow obstruction in patients with chronic obstructive pulmonary disease (COPD). In mechanically ventilated subjects, expiratory airways obstruction can only be estimated from relaxed expirations. The aim of this study was to quantify the degree of airways obstruction from relaxed expiratory flow‐volume curves in mechanically ventilated patients with COPD.

Methods: As measure of airflow obstruction, the effective time constant during the last 50% of expired volume (τ) was calculated. For bedside monitoring, τ was recalculated as the slope of the flow during the last 50% of expired volume (SF50). In order to study reproducibility, the variables were calculated from consecutive breaths and at different levels of end‐expiratory lung volume (EEV). The SF50 and the τ were correlated with the forced expiratory volume in 1 s (FEV1) measured prior to the start of ventilatory support.

Results: Twenty‐seven patients were studied with a FEV1 expressed as percentage predicted of 31±12% (mean±SD). The SF50 amounted to 19±10°. A positive linear correlation was established between SF50 and the FEV1, (%pred), (r=0.90, P<0.0001). The τ showed an exponential relationship with FEV1 (%pred), (r2=0.78) From 5 consecutive breaths the mean variation coefficient of SF50 was 5±2%. Changes of ΔEEV from 0.05 to 1.00 L did not affect the SF50‐values. In 12 patients, mechanically ventilated for respiratory diseases other than COPD, mean τ and SF50 were significantly different from the COPD‐patients (P<0.0001).

Conclusions: This study indicates that relaxed expiratory flow‐volume curves can be used to assess airflow obstruction in mechanically ventilated patients with COPD. This information can be used to adapt ventilatory settings.
Venous gas embolism: Detection with pulsed Doppler guided by two‐dimensional echocardiography
Authors: Boussuges A. , Molenat F. , Carturan D. , Gerbeaux P. , Sainty J. M.
Published: March 2003

Background: Venous gas embolism is a rare but severe event in critically ill patients and the diagnosis should be obtained as soon as possible. Ultrasonography is a sensitive, non‐invasive, and bedside means of detection.

Method: We prospectively estimated the performance of two‐dimensional (2D) echocardiography and pulsed Doppler guided by 2D echocardiography in the detection of venous embolism. We used, as a model of venous gas embolism, the decompression following a recreational dive. This activity is responsible for circulating bubbles related to nitrogen desaturation.

Results: Venous gas emboli were detected following 44 of 68 dives in 20 of 24 divers. Gas emboli in 36 cases (16 divers) was shown by 2D echocardiography. Parasternal short‐axis and right‐cavity longitudinal views were the best views for positive detection. Pulsed Doppler confirmed the existence of venous gas emboli in all of the 36 cases with positive detection by 2D echocardiography. In 8 other cases, pulsed Doppler detected circulating bubbles, which were not observed by using 2D echocardiography. Discrepancies were observed in 4 divers with an echographic image of medium or poor quality.

Conclusion: Combined utilization of 2D echocardiography and pulsed Doppler provides a better method for the detection of venous gas embolism than 2D echocardiography alone. This protocol could be used for critically ill patients suspected of venous air embolism.
Influence of temperature on tracheal tube cuff pressure during cardiac surgery
Authors: Souza Neto E. P. , Piriou V. , Durand P. G. , George M. , Evans R. , Obadia J. F. , J. Lehot J.
Published: March 2003

Background: Lateral wall pressure may cause tracheal injury by affecting tracheal capillary blood flow. Damage to the trachea is less severe when lateral wall pressure exerted by the endotracheal tube cuff does not exceed the mean capillary perfusion pressure of the mucosa. The purpose of this study was to determine the effects of hypothermic and normothermic cardiopulmonary bypass (CPB) on tracheal tube cuff pressure dynamics.

Methods: Twenty‐two patients were studied during normothermic CPB (pulmonary artery blood temperature in the CPB period between 36 and 35°C), and 22 patients during hypothermic CPB (pulmonary artery temperature in the CPB period between 32 and 28°C). A Mallinckrodt Medical Lo‐ContourTM Murphy tracheal tube, with high‐volume, low‐pressure cuff was used without lubricant. Intracuff pressure (ITCP) was recorded at end‐expiration before, during and after cardiopulmonary bypass.

Results: ITCP measurements were different between groups during CPB at aortic cross‐clamping (13.9±0.8 mmHg in the normothermic group versus 11.3±0.4 mmHg in the hypothermic group, P<0.05), and respectively during CPB after aortic declamping (15.3±0.8 mmHg and 12.6±0.8 mmHg, P<0.05) and after CPB at the end of surgery (16.8±0.7 mmHg and 18.6±0.3 mmHg, P<0.05).

Conclusion: We conclude that the ITCP is higher in normothermic CPB than in hypothermic CPB; however, the clinical significance of this observation needs further investigation.
Effects of small peripheral temperature changes on the evoked baseline electromyographic response
Authors: Santanen O. A. P. , Paloheimo M. P. J.
Published: March 2003

Background: Since muscle temperature seems to influence the electrically evoked compound muscle action potentials, we wanted to quantificate the effect of light external cooling and warming on evoked responses in a clinical setting.

Methods: In ophthalmic surgical patients (ASA I–III), evoked electromyographic (EMG) responses to supramaximal train‐of‐four stimuli were measured once a minute. After obtaining an initial baseline (100%) where temperatures of the first dorsal interosseal muscle and the skin above it had stabilised, the patients’ hands were cooled to stable temperatures by a blower (room air). A new baseline was established and, subsequently, the hand re‐warmed to the starting temperature. The cooling procedure was repeated, operation time allowing.

Results: The mean (range) muscle and skin temperature changes were from 36.0°C (35.5–37.1) to 34.6°C (33.2–36.1) and 35.7°C (35.0–36.7) to 32.0°C (29.4–35.6), respectively. The mean (range) change of the EMG‐response was 8.0%/°C (0.3–16.5) for the muscle and 4.1%/°C (0.3–37.9) for the skin. Wide individual variability was evident.

Conclusion: The electrically evoked EMG‐response is sensitive to even small changes in temperature at the measurement site. Therefore, when applying the evoked EMG in neuromuscular studies, peripheral skin or muscle temperatures need to be monitored, and attempts to stabilise the temperature of the monitored muscles should be made.
One‐lung ventilation when intubation is difficult – presentation of a new endobronchial blocker
Authors: Arndt G. A. , Delessio S. T. , Kranner P. W. , Orzepowski W. , Ceranski B. , Valtysson B.
Published: March 2003

Background: One‐lung ventilation utilizing a double‐lumen endotracheal tube may be technically difficult or inappropriate in morbidly obese or critically ill patients. In patients requiring awake fiberoptic intubation, double‐lumen tube placement may be impossible. Wire‐guided endobronchial blockade through a conventional endotracheal tube is a new alternative for these patients.

Methods: A 44‐year‐old, 133 kg female patient was scheduled to undergo a thoracotomy for transthoracic fundoplication. A wire‐guided endobronchial blocker (WEB) was placed following rapid‐sequence induction and intubation with an 8.0 OD single‐lumen endotracheal tube with the aid of a pediatric bronchoscope.

Results: The WEB, using a guiding loop, was placed with ease and allowed effective one‐lung ventilation.

Conclusion: The WEB system allows one‐lung ventilation to be achieved with a conventional endotracheal tube. The need for reintubation at the end of surgery is eliminated and endotracheal tube cross‐sectional area is conserved.
Cauda equina syndrome after spinal anaesthesia with hyperbaric 5% lignocaine: A review of six cases of cauda equina syndrome reported to the Swedish Pharmaceutical Insurance 1993–1997
Authors: Loo C. C. , Irestedt L.
Published: March 2003

Six cases of cauda equina syndrome with varying severity were reported to the Swedish Pharmaceutical Insurance during the period 1993–1997. All were associated with spinal anaesthesia using hyperbaric 5% lignocaine. Five cases had single‐shot spinal anaesthesia and one had a repeat spinal anaesthetic due to inadequate block. The dose of hyperbaric 5% lignocaine administered ranged from 60 to 120 mg. Three of the cases were most likely caused by direct neurotoxicity of hyperbaric 5% lignocaine. In the other 3 cases, direct neurotoxicity was also probable, but unfortunately radiological investigations were not done to definitely exclude a compressive aetiology. All cases sustained permanent neurological deficits. We recommend that hyperbaric lignocaine should be administered in concentrations not greater than 2% and at a total dose preferably not exceeding 60 mg.
Pharmacokinetics of eltanolone in male and female patients following intravenous bolus injection
Authors: Dale O. , Hynne H. , Parivar K. , Johansson E. , Widman M.
Published: March 2003

Background: The pharmacokinetics of the steroid anesthetic eltanolone have been studied in male volunteers. However, steroids may exhibit gender‐related differences in pharmacokinetics and surgery may alter drug disposition.

Methods: Male (n=12) and female (n=9) ASA 1–2 patients (age 26–45 yrs) undergoing discectomy with microsurgical technique were included. Anesthesia was induced with eltanolone 0.75 mg/kg and maintained with nitrous oxide, fentanyl and atracurium. Venous blood was sampled for up to 12 h and analyzed for eltanolone and its major metabolites.

Results: Induction was smooth and anesthesia uneventful, except that five cases developed a mild transient erythema. Loss of verbal contact occurred within 20–60 s. Pharmacokinetics in one person deviated significantly from the rest of the subjects. No difference between groups with respect to the primary outcome variable noncompartmental clearance (Cl, 1/min) 1.7 vs 1.6, was found. However, the volume of distribution at steady state (Vss, l/kg) was larger in women (3.1) compared to men (1.3). The pharmacokinetics followed a three‐compartment model. The half‐lives (min) of the α, β and γ phases (men vs women, medians) were 1.5 vs 2.2, 42 vs 40 and 222 vs 360, respectively. Area under the curve (AUC, min μg/l) was 39810 vs 34905. Context‐sensitive modelling indicated that it may take 10 min more for women than men to recover from an eltanolone infusion of 2 h duration.

Conclusion: The gender‐related differences in the pharmacokinetics of eltanolone were small, and of little clinical significance for induction of anesthesia with eltanolone.
Metabolic regulation of cardiac output during inhalation anaesthesia in dogs
Authors: Scheeren T. W. L. , Schwarte L. A. , Arndt J. O.
Published: March 2003

Background: The metabolic regulation of tissue blood flow manifests itself in a linear relation between blood flow and oxygen consumption, the latter being the independent variable. It is unknown, however, if this fundamental physiological principle operates also during inhalation anaesthesia known to be associated with decreases in both cardiac output (Q˙) and oxygen consumption (V˙O2).

Methods: Seven dogs (23–32 kg) with chronically implanted flow probes around the pulmonary artery were repeatedly anaesthetized with halothane, enflurane, isoflurane, sevoflurane, and desflurane at increasing minimum alveolar concentrations (1–3 MAC). Cardiac output (ultrasound transit‐time flowmeter) and V˙O2 (indirect calorimetry) were measured continuously. We also imposed selective changes in Q˙, and thus of O2 supply, to see if and to what extent this would alter V˙O2 during anaesthesia (1.5 MAC).

Results: In awake dogs under basal metabolic conditions, V˙O2 was 4.6±0.1 ml · kg−1 · min−1 and Q˙ 105±3 ml · kg−1 · min−1 (mean±SEM). During inhalation anaesthesia, V˙O2 and Q˙ decreased by approximately 30% and 60%, respectively. The concentration‐effect relations of both variables did not differ between anaesthetics, yielding a uniform Q˙/V˙O2 relation, which was nearly linear in the range (0–2 MAC) with an average slope of 39±1 (range 30–55). Above 2 MAC, Q˙ decreased more for a given change in V˙O2, and O2 extraction increased by 50%, indicating compromised oxygen delivery (D˙O2). Imposed changes in Q˙, both in awake and anaesthetized dogs, yielded Q˙/V˙O2 relations which were notably steeper (slopes 114 to 187) than those observed during inhalation anaesthesia. More important, imposed increases in Q˙ and thus D˙O2 during anaesthesia (1.5 MAC) to rates comparable to that in the awake state produced a much less than proportional increase in V˙O2 without restoring it to baseline.

Conclusions: Inhalation anaesthesia is characterized by a uniform Q˙/V˙O2 relation with an almost linear course at an anaesthetic concentration up to 2 MAC, regardless of the anaesthetic. Metabolic regulation of blood flow apparently operates also during inhalation anaesthesia up to 2 MAC so that the decrease in V˙O2 determines Q˙. This implies that cardiac output alone provides little information on the function of the circulation during inhalation anaesthesia unless related to metabolic demands, i.e. to V˙O2.
Luxury lung perfusion in end‐stage liver disease during liver transplantation
Authors: Stenqvist O. , Olausson M. , Karlsen K. L.
Published: March 2003

Background: End‐stage liver disease is accompanied by a hyperkinetic circulation sometimes combined with hypoxaemia. Nitric oxide overproduction has been described as a possible cause by dilating the vasculature and decreasing cardiac afterload. The aim of this study was to evaluate haemodynamics, ventilation/perfusion matching, alveolar and alveolar dead space ventilation and resistance of systemic and pulmonary vasculature during liver transplantation.

Methods: Ten liver transplantation patients were studied. Cardiac output, CO, was measured with thermodilution technique. Pulmonary shuntflow was calculated from standard formulas. Effective cardiac output, COeff, was defined as the CO in contact with alveolar ventilation, V˙A. Effective alveolar ventilation, V˙Aeff, was defined as V˙A in contact with pulmonary circulation. Measurements were performed during dissection, anhepatic and reperfusion phases.

Results: During the dissection phase the shunt was 23±3%, COeff was 7.9±0.6 l/min, SVR was 620±67 dyn  ·  s/cm5, V˙Aeff was 3.4±0.5 l/min, SaO2 was 98±1% and Sv¯O2 was 86±2%. Corresponding values during the anhepatic phase were 16±2%, 5.6±0.4 l/min, 931±78 dyn  ·  s/cm5, 3.1±0.2 l/min, 99±1% and 88±1%. During the reperfusion phase the values returned to levels close to that of the dissection phase. The reduction of COeff between the dissection and the anhepatic phase was significant (P<0.01).

Conclusions: The low vascular resistance is accompanied by a high cardiac output. In spite of the high shunt fraction, these patients were not hypoxaemic. This is explained by the fact that the increased cardiac output leads to a decrease in arterio‐mixed venous oxygen content difference and an increase in mixed venous oxygenation level, Sv¯O2 86–88%, normal value ≈70%. The V˙Aeff/COeff in this study was ≈0.5, i.e. the effective cardiac output, COeff is 235, 180 and 197% of the effective alveolar ventilation, V˙Aeff during the three phases. Thus, about twice the amount blood is oxygenated as compared to a normodynamic situation, which compensates for the effect of the shunt flow on oxygenation.
Effects of a leucocyte depleting arterial line filter on perioperative proteolytic enzyme and oxygen free radical release in patients undergoing aortocoronary bypass surgery
Authors: Mair P. , Hoermann C. , Mair J. , Margreiter J. , Puschendorf B. , Balogh D.
Published: March 2003

Background: Proteolytic enzymes and oxygen free radicals released from activated leucocytes contribute significantly to the organ dysfunction associated with cardiopulmonary bypass. Leucocyte depletion during extracorporeal circulation should reduce the release of these toxic compounds and thereby improve postbypass myocardial and pulmonary function. Recently, a leucocyte‐specific arterial line filter to achieve leucocyte depletion during clinical perfusion has become commercially available. The aim of this study, therefore, was to evaluate the influence of the leucocyte depleting arterial line filter on proteolytic enzyme release, oxygen free radical release and postbypass pulmonary and myocardial function in patients undergoing bypass surgery.

Methods: Forty patients undergoing elective aortocoronary bypass surgery were included into this prospective, randomized clinical study, 20 in the leucocyte depletion (LG‐6 group, leucocyte‐specific arterial line filter) and 20 in the control group (AV‐6 group, standard arterial line filter). White cell count, differential white cell count, plasma elastase concentration, plasma malondialdehyde concentration and C‐reactive protein were determined before, twice during and immediately after cardiopulmonary bypass, at the end of surgery and 6 and 20 h thereafter.

Results: White cell count, differential white cell count, malondialdehyde and C‐reactive protein were not significantly different between LG‐6 and control patients. Plasma elastase concentrations were significantly (P≤0.03) higher during and immediately after extracorporeal circulation in LG‐6 group patients. Need for inotropic support, arterial pO2 after extracorporeal circulation and perioperative CK MB mass and troponin I release were not different between the two groups of patients.

Conclusion: The use of a leucocyte depleting arterial line filter is associated with an increased release of the proteolytic enzyme elastase, but does not reliably and consistently achieve effective leucocyte depletion during clinical perfusion. In contrast to previous studies, we could not demonstrate any significant difference in postbypass pulmonary or myocardial function between patients perfused with the leucocyte‐specific arterial line filter and control patients. Our data do not support the routine use of a leucocyte depleting arterial line filter during clinical perfusion in patients undergoing elective aortocoronary bypass surgery.
Effects of ventilatory pattern on exhaled nitric oxide in mechanically ventilated rabbits
Authors: Forsberg S. , Ludwigs U. , Hedenstierna G.
Published: March 2003

Background: Nitric oxide [NOexp] is present in exhaled air in many species. During experiments on pressure‐controlled inverse ratio ventilation (PCIRV) in rabbits, increased [NOexp] was observed during PCIRV. The present study was undertaken to clarify which component of PCIRV increased [NOexp].

Methods: Three groups of six New Zealand White rabbits were anaesthetised and mechanically ventilated. Exhaled nitric oxide, lung mechanics and gas exchange were measured using an experimental protocol designed to assess the effects of variations in 1) flow profile, 2) inspiratory time and 3) time‐weighted tidal volume. Ventilator settings used were volume and pressure control ventilation at I:E ratios of 1:2 and 4:1.

Results: Constant and decelerating flow gave comparable [NOexp] levels (20.0±6.4 vs. 21.9±7.7 ppb, n.s.) when time‐weighted tidal volume was kept constant. Using conventional (I:E 1:2) or inverted (I:E 4:1) I:E ratios in combination with decelerating flow and constant time‐weighted tidal volumes did not alter [NOexp] (26.0±3.6 vs. 24.0±5.8 ppb, n.s.). An increased time‐weighted tidal volume produced by pressure control with an I:E ratio of 4:1 increased [NOexp] (29.6±7.4) in comparison to constant (19.3±4.1, P<0.05) and decelerating flow ventilation (19.6±3.6, P<0.05) with I:E ratios of 1:2.

Conclusion: The exhaled NO concentration was affected by ventilator setting. Increased levels of [NOexp] were observed with increases in time‐weighted tidal volume, whereas changes in flow pattern and inspiratory time did not seem to influence airway NO production or release.
Growth of Escherichia coli in propofol, lidocaine, and mixtures of propofol and lidocaine
Authors: Sakuragi T. , Yanagisawa K. , Shirai Y. , Dan K.
Published: March 2003

Background: Microorganisms grow rapidly in propofol. Extrinsic contamination of propofol is thought to be a source of postoperative sepsis and wound infection. We studied growth of a strain of Escherichia coli in thiopental, propofol, lidocaine, and mixtures of propofol and lidocaine.

Methods: The pathogen was exposed to 2.5% thiopental; 1.0% propofol; 1.0%, 2.0% and 4.0% preservative‐free lidocaine; and propofol solutions containing 0.25%, 0.5%, 1.0%, 2.0%, or 4.0% lidocaine for 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 h at room temperature, respectively. The inocula from these suspensions were cultured for 48 h at 37°C after the antimicrobial activity of the local anesthetics in the inocula was inactivated by a 1 : 1000 dilution with distilled water.

Results: No organisms grew after exposure to 2.5% thiopental. The exposure of E. coli to propofol increased the colony count to approximately 90 times the control count. The colony counts of E. coli after exposure to 1.0%, 2.0% and 4.0% lidocaine and 0.25%, 0.5%, 1.0%, 2.0% and 4.0% lidocaine in 1.0% propofol were lower than the counts after exposure to 1.0% propofol (P=0.0048, 0.0027, 0.0003, 0.0503, 0.0188, 0.0080, 0.0044, and 0.0001, respectively). The growth rate of the microorganism was significantly higher in cultures exposed to 1.0% propofol than that in cultures exposed to lidocaine alone or lidocaine‐propofol mixtures (P<0.0001, respectively).

Conclusion: Lidocaine possesses bacteriostatic activity against E. coli. Addition of lidocaine to propofol confers its bacteriostatic activity to the mixture and may decrease the hazard of infection associated with the extrinsic contamination of propofol.
Do blood levels of neuron‐specific enolase and S‐100 protein reflect cognitive dysfunction after coronary artery bypass?
Authors: Rasmussen L. S. , Christiansen M. , Hansen P. B. , Moller J. T.
Published: March 2003

Background: Neuron‐specific enolase (NSE) and S‐100 protein have been used as markers for major brain damage. Cognitive dysfunction after cardiac surgery represents subtle brain damage that is detected by neuropsychological testing. We hypothesised that blood levels of NSE and S‐100 protein would increase after coronary artery bypass surgery and that the change in blood level would correlate with the change in cognitive function.

Methods: We included 35 elderly patients undergoing coronary artery bypass surgery. Neuropsychological testing was performed before surgery and postoperatively at discharge from hospital and after 3 months using a neuropsychological test battery. Serum levels of NSE and S‐100 protein were measured before surgery and postoperatively after 24 h and 48 h.

Results: Serum level of both NSE and S‐100 protein increased significantly 24 and 48 h after coronary artery bypass. Only the increase in NSE after 24 h was found to correlate with the degree of cognitive dysfunction at discharge from hospital. The increase in S‐100 protein after 24 h correlated significantly with the duration of cardiopulmonary bypass.

Conclusion: NSE seems to be a useful blood marker for early cognitive dysfunction after coronary artery bypass surgery.
Preoperative anxiety is associated with a high incidence of problematic behavior on emergence after halothane anesthesia in boys
Authors: Aono J. , Mamiya K. , Manabe M.
Published: March 2003

Background: In our clinical experience, children who are crying before anesthesia are more likely to show agitated behavior on emergence.

Methods: One hundred and ten boys aged 3–6 years old (ASA 1) who underwent circumcision were studied. The children were assigned to one of two groups, depending on their attitude during induction: the anxious group and the calm group. Anesthesia was induced by inhalation of halothane in oxygen, and was maintained at 1% throughout surgery. For intra‐ and postoperative analgesia, caudal block with 0.5 ml/kg of 0.25% plain bupivacaine and topical infiltration with 1 to 2 ml of 1% lidocaine were provided for all patients. The incidence of delirium on emergence was compared between the groups.

Results: We excluded 4 boys showing signs of incomplete pain relief. Twenty of 27 boys in the anxious group showed a significantly greater incidence of problematic behavior on emergence, compared to 5 of 79 in the calm group.

Conclusion: The boys who were anxious before anesthesia showed a significantly greater incidence of problematic behavior on emergence from halothane anesthesia, compared with the boys who were calm before anesthesia.
Enhancement of intrathecal lidocaine by addition of local and systemic clonidine
Authors: Dobrydnjov I. , Samarütel J.
Published: March 2003

Background: Enhancement of local anaesthetic‐produced regional blocks by clonidine seems well established. There are insufficient data about dose‐effect relationship of combinations of clonidine with individual agents, efficiency of local versus systemic administration of clonidine, and comparative evaluation of clonidine with vasoconstrictors. Because of unavailability of long‐acting local anaesthetics at the time of study, our aim was to evaluate augmentation of lidocaine spinal block with local or systemic clonidine and to compare the results with the efficacy of intrathecal phenylephrine.

Methods: Ninety pts of age 50–72 yrs with ASA 1–4 physical status, scheduled for open prostatectomies, hysterectomies or ostheosynthesis of fractured hip were randomized to one of 6 treatment groups, 15 pts in each. Patients received intrathecally (L3–L4) either 100 mg of plain lidocaine (group L100); or a mixture of lidocaine 40 and 80 mg with clonidine 100 μg (groups L40‐C100 and L80‐C100); or a combination of lidocaine 40 and 80 mg with clonidine 300 μg orally 60 min before spinal puncture (L40‐C300 and L80‐C300). Addition of intrathecal phenylephrine 5 mg to 80 mg of lidocaine was also investigated (L80‐P5).

Results: There were no significant intergroup differences concerning demographic data or type of surgery. All operations (duration up to 150 min) were completed without need for analgesic supplementation. The addition of clonidine resulted in a significant reduction of the onset time of spinal block and prolongation of the duration of sensory and motor blocks compared to plain lidocaine or lidocaine with phenylephrine. In spite of the well‐known hypotensive action of α2‐agonists, haemodynamic depression only in group L80‐C300 was significantly more pronounced than in L100 and L80‐P5 groups. The least decrease of BP and minimal need of rescue ephedrine among all patients studied were recorded in the group receiving low dosage of lidocaine with intrathecal clonidine (L40‐C100). Sedation occurred in most patients receiving clonidine.

Conclusion: Our results indicate that addition of clonidine to lidocaine, irrespective of the route of administration, prolongs the duration of spinal block and permits a reduction of the lidocaine dose needed for a given duration of block. Addition of phenylephrine results in a less pronounced statistically significant prolongation of anaesthesia. The regression of sensory block before restoration of motor function seems to be a specific (and unfortunate) effect of both clonidine and phenylephrine.
Sameridine – intrathecal injection in the rat
Authors: Karlsten R. , Gordh T. , Kristensen J. D. , Ask A.‐L. , Svensson B. A.
Published: March 2003

Background: Sameridine is a type of compound with both local anaesthetic and analgesic effects with the clinical intention to be used intrathecally (IT) in order to provide both surgical anaesthesia and prolonged postoperative analgesia. Before new drugs are introduced for clinical use, they must be tested for potential toxic effects.

Methods: In the present study sameridine (5 or 10 mg/ml), bupivacaine (5 mg/ml) or saline (9 mg/ml) was injected intrathecally in rats twice, daily (at 07:00 and 19:00), 5 days a week for 2 weeks. Thereafter, the rats were anaesthetised, perfused and the spinal cords were prepared for microscopic investigation. A morphologic method, using light and electron microscopic examination of the cross‐section of the spinal cord, was combined with a quantitative morphometric analysis of the number and size of neuronal cells in the dorsal horn as a sensitive indicator of neurotoxicity. Using the laser‐Doppler flowmetry technique, the effects of saline and sameridine (1, 5 and 10 mg/ml) on spinal cord blood flow (SCBF) was studied.

Results: No signs of neurotoxicity could be seen in any of the animals and no significant differences were seen when comparing the cell number or cell sizes in the groups injected with sameridine, bupivacaine or saline. After IT administration of 10 mg/ml sameridine a significant, short‐lasting, decrease in SCBF (72% of pre‐drug value) was seen.

Conclusion: In conclusion, our studies do not show any signs of neurotoxic effects of IT administration of sameridine in the rat. A transient decrease in SCBF was noted after IT injection of sameridine 10 mg/ml.
The role of stress in anaesthetists’ health and well‐being
Authors: Jackson S. H.
Published: March 2003

Stress is an inevitable part of our personal and professional lives. When poorly managed, stress will accumulate to levels that become injurious to our health and well‐being. Burnout is one such consequence. However, because stress is an activie process, with the proper knowledge and skills, we can learn to better manage and control its level of intensity. This paper examines the stress cycle and especially those aspects that are unique to the practice of medicine and anaesthesia. Sleep deprivation and physical fatigue are analyzed as key stressors. The role of the medical marriage and dual‐career relationships are scrutinized. The importance of retaining the humanistic essence of medicine is emphasized. Stress management strategies and coping responses, including self‐care and humor, are discussed.
Effects of amide local anaesthetics on eicosanoid formation in burned skin
Authors: Jönsson A. , Cassuto J. , Tarnow P. , Sinclair R. , Bennett A. , Tavares I. A.
Published: March 2003

Bacground: Previous studies have demonstrated potent inhibition of burn oedema and progressive ischaemia by local anaesthetics. Since eicosanoids have been suggested to play an important role in the pathophysiology of burns, we compared in the present ex vivo study the effects of topical lidocaine/prilocaine cream (EMLA®, ASTRA, Sweden) and intravenous lidocaine with that of saline on eicosanoid formation by normal and burned rat skin.

Methods: A full‐thickness burn trauma was induced in the abdominal skin. All the agents were given 5 min postburn until 2 h after the trauma. The experimental skin was subsequently removed and incubated in Krebs solution for 1 h. Eicosanoid concentrations in the solution were analysed by radioimmunoassay.

Results: EMLA® cream induced a significant inhibition of TXB2 (P<0.05) and 6‐Keto‐PGF1α (P<0.01) but not of PGE release from burned skin as compared to saline treatment. Intravenous lidocaine infusions did not significantly influence the release of any of the measured eicosanoids versus saline.

Conclusion: In conclusion, the lack of effect of intravenous lidocaine could relate to the severe burn trauma inducing rapid ischaemia which may have interfered with the delivery of the agent to the burned tissues or to insufficient concentrations achieved in the burn area. Topical treatment of burned skin with a local anaesthetic cream significantly reduced the release of TXB2 and 6‐Keto‐PGF1α, suggesting a possible mechanism of action in progressive burn ischaemia.
Systemic levels and preportal organ release of tissue‐type plasminogen activator are enhanced by PEEP in the pig
Authors: Seeman‐Lodding H. , Häggmark S. , Jern C. , Jern S. , Johansson G. , Winsö O. , Biber B.
Published: March 2003

Background: Endothelium‐derived tissue‐type plasminogen activator, t‐PA, is the key enzyme in the initiation of endogenous thrombolysis. Plasma levels of t‐PA increase in response to sympatho‐adrenergic activation. In the mesenteric vascular bed an increased norepinephrine spillover has been observed during positive end‐expiratory pressure ventilation, PEEP. This experimental study examines the effects of PEEP‐induced alterations on regional release rates and systemic levels of t‐PA in vivo.

Methods: The protocol included measurements of arterio‐venous concentration gradients of t‐PA and the respective plasma flow across the pulmonary, coronary, hepatic and preportal vascular beds, in pigs, during zero‐PEEP and at 2, 4 and 10 min after the application of a PEEP of 10 cm H2O. Both total plasma t‐PA antigen (ELISA with a porcine t‐PA standard) and active t‐PA (spectrophotometric functional assay) were determined.

Results: During zero‐PEEP, a high preportal basal net release and hepatic net uptake of total t‐PA was observed. With PEEP, the magnitude of the preportal net release of t‐PA was markedly enhanced (+24±5%), as was hepatic net uptake (+21±8%), simultaneously to a significant decrease in liver plasma flow (−30±2%). PEEP‐induced alterations in active t‐PA mirrored those observed in total t‐PA. No significant net fluxes of total or active t‐PA were observed across the coronary or the pulmonary vascular beds.

Conclusions: Clinically used levels of PEEP induce increases in net release of endothelially derived t‐PA within preportal organs. The application of PEEP is associated with increased systemic levels of total and active t‐PA, in spite of a simultaneous increase in hepatic net uptake, indicating that the preportal vascular bed can not account for the systemic t‐PA response.
Tropisetron or droperidol in the prevention of postoperative nausea and vomiting
Authors: Jokela R. , Koivuranta M.
Published: March 2003

Background: Women undergoing laparoscopic cholecystectomy are susceptible to postoperative nausea and vomiting (PONV). This study was undertaken to evaluate the efficacy of tropisetron or droperidol for preventing PONV after laparoscopic cholecystectomy.

Methods: In a prospective, randomised, double‐blind trial, 120 female patients received either tropisetron 5 mg or droperidol 1.25 mg intravenously at the beginning of surgery. A standard general anaesthetic technique and postoperative analgesia were used. Nausea, emetic episodes and the need for rescue medication were recorded for 24 h postoperatively.

Results: Nausea was experienced by 55% of the patients in the tropisetron group and by 62% in the droperidol group (ns). The incidence of emetic episodes was 20% and 52% (P=0.001) in the two groups, respectively. Rescue antiemetic medication was needed in 42% and 50% (ns) of the patients, respectively. Patients in the droperidol group were more drowsy in comparison with patients in the tropisetron group, mean sedation score being 6.7 vs 5.7, respectively (P=0.023). No difference in other side‐effects was observed.

Conclusion: Tropisetron, when compared with droperidol, had no better efficacy on the prevention of postoperative nausea but resulted in a significantly lower incidence of vomiting after laparoscopic cholecystectomy.
Pollution with nitrous oxide using laryngeal mask or face mask
Authors: Jenstrup M. , Fruergaard K. O. , Mortensen C. R.
Published: March 2003

Background: As environmental pollution by nitrous oxide may influence the health of the personnel working in operating theatres, the incidence and magnitude of nitrous oxide (N2O) leakage, when using a face mask or a laryngeal mask airway (LMA) for controlled ventilation, were studied in 34 patients scheduled for elective cystoscopy.

Methods: A semi‐closed gas delivery ventilation system with active scavenging was used. The N2O concentrations were measured every 8 s at a position 30 cm above the patient's mouth with a N2O gas monitor (GD 200, Simrad Optronics).

Results: When using a face mask, the leakage of N2O resulted in a N2O concentration of 157 (85–332) p.p.m. (parts per million) (median concentration and 25% and 75% percentiles). With the LMA, a lower median concentration of N2O of 60 (28–126) p.p.m. was found (P=0.04). With the face mask, a concentration above 100 p.p.m. was found during 51% of the exposure time compared to 24% of the time in the LMA group.

Conclusion: Environmental pollution was less with the LMA than the face mask, but under the conditions of the study both modes of airway management were associated with levels of N2O peak concentrations in the breathing zone of anaesthetists that are deemed to be excessively high by the Danish National Institute for Occupational Safety.
Clinical experience using intrathecal (IT) bupivacaine infusion in three patients with complex regional pain syndrome type I (CRPS‐I)
Authors: Lundborg C. , Dahm P. , Nitescu P. , Appelgren L. , Curelaru I.
Published: March 2003

Background and aim: To date, there is no reliable method for treating the severe pain and for modifying the natural evolution of CRPS‐I. Therefore, we explored the effect of long‐term IT bupivacaine infusion (with or without buprenorphine) on this syndrome.

Patients and methods: (a) Patients: two women and one man, 25, 31 and 42 years old, with CRPS‐I of the lower (n=2) or upper (n=1) extremity lasting for 4 and 5 months, and 14 years. (b) Interventions: insertion of externalized IT catheters; IT infusion of buprenorphine 0.015 mg/ml and bupivacaine 4.75 mg/ml (n=1), or only bupivacaine 5 mg/ml (n=2) from external electronic pumps.

Results: The IT treatment lasted for 172, 282 and 668 days. The mean/maximal daily doses of the IT bupivacaine were 39/66, 55/80 and 69/125 mg, respectively. The pain intensity decreased from VASmean=7±1 to VASmean=2±2. None of the patients had regression of allodynia, edema, and trophic disturbances in the affected extremities. In 2 patients, the IT treatment did not prevent spread of the disease to the opposite extremity or the occurrence of phantom pain and stump allodynia after amputation. The IT catheters were withdrawn as being no longer needed: in 2 patients 56 and 458 days after amputation of the involved extremity, and in another one before replacement of the IT bupivacaine infusion with epidural dorsal column stimulation (EDCS). After termination of the IT treatment, the patients were observed for 1437, 1575, and 2689 days (until September 1, 1998). At that date, all the patients were alive, and still affected by their CRPS‐I, either in the amputation stump (n=2), and/or in the opposite or remote extremities (n=2); further, two were unemployed and one worked for 75% of the time. One of them was taking up to 1500 mg of slow‐release morphine to cope with pain.

Conclusion: The IT pain treatment with bupivacaine (with or without buprenorphine) alleviated the “refractory” pain, but affected neither the associated symptoms and signs of the CRPS‐I, nor its natural evolution. Thus, the IT treatment cannot be recommended in preference to other pain treatment regimens for CRPS‐I.
Perioperative gastric tonometric PCO2 and intramucosal pH in patients undergoing liver transplantation
Authors: Rønholm E. , Runeborg J. , Karlsen K. L. , Tomasdottir H. , Åneman A. , Bengtsson A.
Published: March 2003

Background: Extensive research has focused on the role of insufficient gastro‐intestinal perfusion and inflammatory activation in the development of organ dysfunction during critical illness. In patients undergoing liver transplantation, portal and caval vein clamping leads to gastro‐intestinal and lower extremity venous congestion during the anhepatic phase, and studies suggest that gastro‐intestinal perfusion may be compromised. This study was performed to investigate gastro‐intestinal perfusion in patients undergoing liver transplantation.

Methods: In 16 patients undergoing liver transplantation, perioperative gastric tonometry with determination of tonometric PCO2, tonometric‐arterial PCO2 gradient and intramucosal pH were performed. Blood gases were obtained simultaneously from the arterial and portal vein blood.

Results: Tonometric PCO2 was 4.6 (4.2/5.3) kPa preoperatively and increased to 5.6 (4.5/6.0) kPa during the anhepatic phase (P<0.01), while the tonometric‐arterial PCO2 gradient increased from −0.3 (−0.5/0.0) kPa preoperatively to 0.7 (0.3/1.2) kPa during the anhepatic phase (P<0.01). Intramucosal pH decreased to 7.27 (7.21/7.32) u during the anhepatic phase (P<0.01, compared to preoperatively). The portal vein PCO2 was not significantly different from arterial PCO2 or tonometric PCO2 at any measurement point.

Conclusion: This study demonstrates that clinical liver transplantation is associated with gastro‐intestinal perfusion in the range of aerobic metabolism. The results do not support the presence of gastro‐intestinal perfusion in the range of anaerobic metabolism.
Intraperitoneal and sigmoid colon tonometry in porcine hypoperfusion and endotoxin shock models
Authors: Koga I. , Stiernström H. , Christiansson L. , Wiklund L.
Published: March 2003

Background: The objective of the present study was to assess the accuracy of an air tonometry device in vivo within a wide range of regional carbon dioxide tension (PrCO2) values by using saline tonometry as the standard and to investigate the possibilities to monitor perfusion of the intestine by tonometry in the intraperitoneal cavity.

Methods: Piglets were anesthetized and mechanically ventilated. A pair of tonometry catheters was placed in the sigmoid colon, while another pair was placed intraperitoneally in the right lower quadrant of the abdomen. Air tonometric regional PCO2 (aPrCO2) was measured every 15 min intraperitoneally and every 20 min in the sigmoid colon. Saline tonometric measurements were made every 30 min and steady‐state values (ssPrCO2) were derived. Hypoperfusion shock was induced by graded constriction of the aorta. Endotoxin shock was induced by administration of lipopolysaccharide (LPS).

Results: The obtained average PrCO2 (=matched (aPrCO2+ssPrCO2)/2) values ranged from 5.1 kPa to 14.7 kPa. Regional air PCO2 (aPrCO2) and steady‐state saline PCO2 (ssPrCO2) exhibited a strong positive linear relationship (r=0.959). The 95% confidence interval of the mean of dPrCO2 (=aPrCO2−ssPrCO2) was 0.31–0.46 kPa. Intraperitoneal tonometric PrCO2 was lower than intraluminal PrCO2 in the sigmoid colon, and was also more sensitive to circulatory changes than sigmoid colon PrCO2.

Conclusion: The regional air PCO2 (aPrCO2) showed good agreement with the steady‐state saline regional PCO2 (ssPrCO2). Intraperitoneal measurements may be an alternative method of monitoring intestinal perfusion after abdominal surgery.
Dopamine reduces gastric tone in a dose‐related manner
Authors: Levein N. G. , Thörn S. E. , Lindberg G. , Wattwil M.
Published: March 2003

Background: Dopamine may have effects on gastrointestinal motility. The aim of this study was, therefore, to determine whether dopamine reduces gastric tone and whether the effects of dopamine can be blocked by a dopamine antagonist.

Methods: Eight healthy male volunteers were studied on two occasions in a randomized order. A continuous infusion of incremental doses of dopamine (2.5, 5.0, 7.5 μg kg−1 min−1) was given on both occasions. Ten milligrams of the dopamine‐antagonist metoclopramid was given before the dopamine infusion on one occasion and during the dopamine infusion (7.5 μg kg−1 min−1) on the other occasion. The gastric tone was measured by an electronic barostat, an instrument with an electronic control system that maintains a constant preset pressure within an airfilled, flaccid intragastric bag by means of momentary changes in the intragastric volume of air. Volume and pressure in the gastric bag were continuously recorded by the electronic barostat and sampled in a computer.

Results: Dopamine induced a dose‐related increase in the intragastric bag volume. Metoclopramid given as a 10 mg i.v. bolus dose during the infusion of dopamine significantly decreased the intragastric bag volume, but 10 mg of metoclopramid i.v. before the dopamine infusion did not influence the bag volume per se.

Conclusion: Dopamine decreases gastric tone in a dose‐related manner and 10 mg of the dopamine‐antagonist metoclopramid is not enough to fully reverse these effects.
Perioperative transcutaneous pacemaker in patients with chronic bifascicular block or left bundle branch block and additional first‐degree atrioventricular block
Authors: Gauss A. , Hübner C. , Meierhenrich R. , Röhm H.‐J. , Georgieff M. , Schütz W.
Published: March 2003

Background: Complete heart block is dreaded perioperatively in patients with chronic bifascicular or left bundle branch block (LBBB) and additional first‐degree A‐V block. Our aim was to investigate the necessity as well as the efficacy and safety of transcutaneous pacing in the perioperative setting.

Methods: Thirty‐nine consecutive patients with asymptomatic chronic bifascicular block or LBBB and prolongation of the P‐R interval scheduled to undergo surgery under anesthesia were prospectively enrolled in the study. Preoperatively, a transcutaneous pacemaker (PACE 500 D, Osypka Co.) was applied; its efficacy was checked with intra‐arterial blood pressure measurement; the pain level was recorded. Additionally, 24‐h Holter monitoring (CM2, CM5) was applied. Occurrences of a block progression or a bradycardia of <40 beats/min with hemodynamic impairment were the defined end points.

Results: Thirty‐seven of the 39 patients (95%) could be successfully stimulated with a median current strength of 70 mA; whereby 33 of the 39 patients felt moderate to severe pain. There was no perioperative block progression. Three cases of bradycardia of <40 beats/min with a critical drop in blood pressure occurred; but these patients were successfully treated with drug therapy without pacemaker stimulation.

Conclusion: The perioperative application and testing of the pacemaker was safe and could be performed in nearly all patients successfully. However, we do not consider a routine prophylactic transcutaneous placement in patients with chronic bifascicular or LBBB and additional first‐degree A‐V block justified. Nevertheless, appropriate drugs and temporary pacemaker equipment should be easily accessible.
Ketamine antagonises alfentanil‐induced hypoventilation in healthy male volunteers
Authors: Persson J. , Scheinin H. , Hellström G. , Björkman S. , Götharson E. , Gustafsson L. L.
Published: March 2003

Background: The effects of ketamine on respiration, alone, or in combination with opioids, have not been completely clarified. Both stimulant and depressant effects have been reported, as well as attenuation of opioid‐induced hypoventilation at the expense of increased oxygen consumption. These conflicting results might partly be due to dose‐dependent mechanisms. We have, therefore, determined the ventilatory effects of ketamine, in combination with alfentanil, using infusions to different pseudo steady‐state concentrations.

Methods: On two separate days, eight healthy male volunteers were given alfentanil as a continuous computer‐controlled infusion, aiming at a plasma concentration of 50 ng  ·  mL−1. After reaching apparent steady‐state for alfentanil, racemic ketamine or placebo was administered in a protocol randomised for the two days. On the ketamine days a computer‐controlled infusion, aiming for escalating ketamine plasma concentrations of 50, 100 and 200 ng  ·  mL−1, was added to the alfentanil infusion. On the placebo days saline was added. Using a face‐mask with an occlusion valve, respiratory parameters were measured during air‐breathing and after 6 repetitive 30‐s CO2 challenges.

Results: The alfentanil infusion induced hypoventilation by decreasing respiratory rate, while tidal volume and respiratory drive were unaffected. This hypoventilation was antagonised by ketamine in a concentration‐dependent manner mainly through an increase in respiratory rate. The CO2 response was not affected by alfentanil or ketamine.

Conclusion: In the dose range of interest for postoperative, intensive‐care and pain‐clinic settings, ketamine antagonises the resting hypoventilation induced by alfentanil.