bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral analysis of heart rate variability during desflurane and isoflurane anaesthesia in patients undergoing arthroscopy
Authors: Widmark Dr.C. , Olaison J. , Reftel B. , Jonsson L.‐E. , Lindecrantz K.
Published: January 2009

Background: We studied the effect of desflurane (DES) and isoflurane (ISO) on heart rate variability (HRV) using power spectral analysis (PSA) of RR‐interval in 30 patients undergoing arthroscopy, prior to induction, during anaesthesia and up to 3 h of recovery. PSA can distinguish low‐frequency (LF) component and respiratory sinus arrhythmia (RSA) that are known to reflect predominantly sympathetic and parasympathetic activity, respectively.

Methods: After premedication with diclofenac and midazolam the anaesthesia was induced with propofol and maintained during spontaneous ventilation with either DES or ISO added to a mixture of nitrous oxide and oxygen. ECG and transthoracic impedance respirometer data were recorded. Power spectra were calculated with an autoregressive modelling method.

Results: Total power (PTOT) and individual power in two frequency bands of the HRV spectrum (PLF, 0.05‐0.15 Hz and PRSA) decreased after induction of anaesthesia in both groups. At 60, 120 and 180 min of recovery the PTOT was back to control‐value in the DES group but remained reduced in the ISO group. Calculated as normalised units, the PLF (nPLF) predominated over the PRSA (nPRSA) during control situations and during recovery. The reverse was the case during maintenance of anaesthesia. Thirty minutes after induction and during surgical stress the ISO group showed higher heart rate compared to the DES group as well as compared to control.

Conclusion: DES and ISO produced similar alterations in studied parameters during the maintenance of anaesthesia. The differences observed between the groups during recovery may indicate an early intact neural reflex control system among the subjects exposed to DES. These results suggest that DES and ISO reduce the total autonomic neural system activity and alter the balance between sympathetic and parasympathetic activities in a comparable way during maintenance of anaesthesia. A more rapid recovery phase among the subjects exposed to DES is linked to differences in pharmacokinetic properties of the inhalation agents.
Sevoflurane preserves endocardial blood flow during coronary ligation in dogs: comparison with adenosine
Authors: Takahata Dr.O. , Ichihara K. , Abiko Y. , Ogawa H.
Published: January 2009

Background: Sevoflurane has been reported to attenuate ischaemia‐induced changes of myocardial metabolism, but the mechanism is still unclear. We examined the effect of sevoflurane on regional myocardial blood flow (RMBF) in the ischaemic area and compared the flow with that in the presence of adenosine.

Method: Twenty‐seven mongrel dogs were anaesthetized with fentanyl infused at the rate of 1μg.kg‐1.min‐1throughout the experiment. Then they were divided into 4 groups; 0, 1, 2 MAC sevoflurane groups and adenosine group. Adenosine was infused into the left ventricle at a rate of 14.5 mg.kg‐1.h‐1. The left anterior descending coronary artery (LAD) was ligated for 3 min. RMBF in the endo‐ and epicardial layers were measured using coloured microspheres.

Results: Sevoflurane decreased both systolic and diastolic blood pressures and LV dp/dt max. Adenosine increased heart rate and coronary flow. The endocardial blood flow in 2 MAC sevoflurane was almost the same as that in the 0 MAC group. Adenosine significantly increased the myocardial blood flow. During 3‐min ischaemia, endocardial blood flow in the ischaemic area under 2 MAC sevoflurane was essentially the same as those in 0 MAC and adenosine groups, though myocardial work in 2 MAC sevoflurane was lower compared with that of the other groups.

Conclusion: Preservation of endocardial blood flow related to the myocardial work during ischaemia occurred during 2 MAC sevoflurane. The decrease in LV dp/dt max induced by 2 MAC sevoflurane is one of the factors responsible for the preservation of the endocardial blood flow during ischaemia.
Mivazerol prevents the tachycardia caused by emergence from halothane anesthesia partly through activation of spinalα2‐adrenoceptors
Authors: Guyaux Dr.M. , Gobert J. , Noyer M. , Vandevelde M. , Wülfert E.
Published: January 2009

Background: Mivazerol (MIV) is anα2‐adrenoceptor agonist designed to prevent adverse cardiac outcome in perioperative patients. The present study was undertaken to determine whether the hyperdynamic state observed at emergence from halothane (HAL) anesthesia in rats could be modulated by MIV and to explore the mode of action of MIV under such conditions.

Methods: Male Sprague Dawley rats were anesthetized with 1% HAL and assisted for respiration (N2O‐O2: 70‐30%). MIV 2.2–15.3μg.kg‐1.h‐1i.v. was infused 30 min before withdrawal of anesthesia and compared for heart rate (HR) and systolic arterial blood pressure (SAP) to control animals treated with saline. In some experiments, animals were pretreated with intrathecal pertussis toxin (T2 level, 0.5μg, 7 d), or i.v. rauwolscine (0.34 mg/kg, 5 min) or were bilaterally stellectomized (30 min) prior to withdrawal of HAL.

Results: Increases in HR (65 bpm, +20%) and in SAP (25 mmHg, +26%) were observed immediately upon discontinuation of HAL and remained constant for at least 30 min. The increase in HR was abolished by removal of the stellate ganglia. MIV dose‐dependently inhibited the increase in HR from 4.8μg.kg‐1.h‐1(68% reduction,P<0.05) without affecting HR or SAP during anesthesia. Inhibition of HR increase was of 98% at 15.3μg.kg‐1.h‐1. This effect was abolished by rauwolscine, and partially (50%) inhibited by pertussis toxin pre‐treatment.

Conclusion: These results demonstrate that withdrawal of HAL anesthesia in the rat produces a sustained increase in HR due to activation of the sympathetic system and that MIV inhibits this tachycardia via activation ofα2‐adrenoceptors located at least in part in the spinal cord.
Myocardial effects of isoflurane in healthy infants and small children
Authors: Gueugniaud Dr.P. Y. , Bertin‐Maghit M. , Abisseror M. , Branche P. , Piriou V. , Bouchard C. , Petit P.
Published: January 2009

Background: In paediatric healthy patients and in real peroperative conditions, the cardiovascular effects of isoflurane have been poorly described.

Methods: We have evaluated the myocardial effects of 1% end‐expired concentration (EEC) of isoflurane in 25 healthy infants or small children undergoing superficial surgical therapy for small burns with a continuous aortic blood flow echo‐Doppler device. Aortic blood flow (ABF) was measured with a small oesophageal probe specially designed for infants. The aortic flowmeter was connected with satelitte devices to visualize the haemodynamic profile variations during the isoflurane inhalation period.

Results: Isoflurane significantly decreased ABF and increased pre‐ejection period/left ventricular ejection time (PEP/LVET), when compared with control values previously recorded 5 min after induction with halothane‐fentanyl and atracurium (respectively, 80 ± 7%, mean ± SD; P<0.001 and 111 ± 11%; P=0.017, 5 min after EEC of isoflurane reached 1%, then respectively, 75 ± 12%; P<0.001 and 119 ± 16%; P<0.001, at the end of the isoflurane inhalation period). These variations reversed to a great extent when isoflurane was switched off (97 ± 17% for ABF; P=0.08 and 105 ± 12% for PEP/LVET; P=0.75). Among the usual parameters, 1% EEC of isoflurane caused no significant changes in heart rate, moderately decreased mean arterial pressure (successively, 88 ± 12%; P=0.045 and 87 ± 19%; P=0.049), but belatedly decreased end‐tidal CO2 pressure (87 ± 11% at the end of the inhalation period (P<0.001) which persisted 5 min after isoflurane was turned off (90 ± 11%; P<0.001)).

Conclusions: These findings suggest that isoflurane can transiently depress cardiac function in healthy infants.
Cardiac arrest due to massive pulmonary embolism following caesarean section. Successful resuscitation and pulmonary embolectomy
Authors: IlsaasM.D C. , Husby P. , Koller M. E. , Segadal L. , Holst‐Larsen H.
Published: January 2009

A woman developed pulmonary embolism with cardiac arrest after caesarean section. Cardiopulmonary resuscitation was performed for 45 min during which echocardiography showed right ventricular dilatation. After stabilization, but still in a critical condition, the patient was transferred by airambulance to a hospital with facilities for extracorporeal circulation. A massive embolus was removed. Some hours after extubation the patient developed respiratory insuffiency and hypovolaemia. Re‐intubation was followed by severe hypotension requiring external cardiac compression for about 15 min. An emergency explorative laparotomy revealed a ruptured liver with a subcapsular haematoma. A critical illness polyneuropathy made prolonged ventilatory support necessary. She recovered without cerebral sequelae.
Effects of propofol on ipecacuanha‐induced nausea and vomiting
Authors: Hammas B. , Hvarfner A. , Thörn S.‐E. , Wattwil M.
Published: January 2009

Background: The purpose of this study was to evaluate if propofol has 5‐HT3 antagonistic effects. Ipecacuanha is known to release serotonin (5‐HT) in the gastrointestinal tract and therefore ipecacuanha syrup was used to induce nausea and vomiting. The 5‐HT3 antagonist ondansetron was used as a control substance.

Results: During the first 150 min after ingestion of ipecacuanha there were no retchings during the ondansetron infusion (P= 0.01 vs placebo, P=0.02 vs propofol) and significantly fewer retchings during propofol infusion compared to placebo (P<0.02). There was no nausea during the ondansetron infusion (P<0.01 vs placebo and propofol) but the volunteers experienced nausea both during the placebo and propofol infusion (NS).

Conclusion: This study in volunteers has shown that propofol reduces the intensity of retching after oral intake of ipecacuanha syrup. As ipecacuanha releases 5‐hydroxytryptamine, it can be concluded that propofol may have a weak 5‐HT3 antagonistic effect.

Method: Ten healthy male volunteers (20–37 years) were studied on three occasions and were randomly allocated to receive a concomitant infusion of propofol (initial bolus 0.1 mg kg‐1 then 1 mg kg‐1h‐1), ondansetron (initial bolus 0.11 mg kg‐1 then 14 μg kg‐1 h‐1) and placebo on either occasion. The infusions started 30 min before oral ingestion of 30 ml of ipecacuanha and continued until 150 min after the intake. The number of retchings was recorded and the intensity of nausea was estimated by the subjects on a visual analog scale.
Near fatal intoxication with controlled‐release morphine tablets in a depressed woman
Authors: Westerling D. , Säwe J. , Eklundh G.
Published: January 2009

Background: A 46‐year‐old woman suffering from a reactive depression was admitted to the emergency room in coma and with severe respiratory failure. She later developed cardiovascular instability and general convulsions. Two days following admission the patient had no respiratory effort but was able to communicate in writing that she had ingested a large amount of controlled‐release morphine tablets. Following treatment with naloxone she was successfully weaned from the respirator the next day.

Methods: Sampling for determination of plasma and urine concentrations of morphine and its metabolites morphine‐3‐glucuronide (M3G) and morphine‐6‐glucuronide (M6G) was started 60 h after the presumed time of intake and continued up to 8 days after admission.

Results: The initial plasma concentrations of morphine, M3G and M6G were 2160, 13100 and 2330 nM, respectively, compatible with a lethal dose in an opioid‐naive patient. The urinary recovery of morphine, M3G and M6G corresponded to 6.8 mmol, equivalent to an oral intake of at least 2500 mg.

Conclusion: The plasma concentrations of morphine and morphine metabolites documented in this case, indicative of considerable absorption of drug, demonstrate that prolonged observation is necessary following intoxications with controlled‐release morphine tablets. This case also highlights the importance of continuous follow‐up of oral morphine therapy, so that unused drug is not left unaccounted for in the patient's home.
Effect of CPAP during cardiopulmonary bypass on postoperative lung function: An experimental study
Authors: Magnusson L. , Zemgulis V. , Wicky S. , Tydén H. , Hedenstierna G.
Published: January 2009

Background: Respiratory failure secondary to cardiopulmonary bypass (CPB) remains a major complication after cardiac surgery. We tested the hypothesis that post‐CPB lung function impairment can be prevented by continuous positive airway pressure (CPAP) applied during the CPB.

Methods: In 6 pigs, CPAP with 5 cmH2O pressure was applied during CPB. Six other pigs served as control, i. e. the lungs were open to the atmosphere during CPB. After median sternotomy, the right atrial appendage as well as the ascending aorta were cannulated. The total CPB duration was 90 min with 45 min cardioplegic arrest. Ventilation‐perfusion distribution was measured with the multiple inert gas elimination technique and atelectasis by CT‐scanning.

Results: Large atelectasis appeared after CPB, corresponding to 14.5%±5.5 (percent of the total lung area) in the CPAP group and 18.7%±5.2 in the controls (P=0.20). Intrapulmonary shunt increased and PaO2 decreased after the CPB in both groups.

Conclusions: We conclude that in this pig model post‐CPB atelectasis is not effectively prevented by CPAP applied during CPB.
Forward blood flow during cardiopulmonary resuscitation in patients with severe accidental hypothermia: An echocardiographic study
Authors: Mair P. , Kornberger E. , Schwarz B. , Baubin M. , Hoermann C.
Published: January 2009

Background: The mechanism responsible for the forward blood flow associated with external chest compression is still controversial. Evidence for both blood flow caused by direct cardiac compression and blood flow generated by a general increase in intrathoracic pressure has been found in experimental as well as clinical studies. No data are available concerning the mechanism causing forward blood flow in hypothermic patients undergoing cardiopulmonary resuscitation. Therefore, echocardiographic findings during external chest compression in seven hypothermic arrest victims are reported.

Methods: All transesophageal echocardiographic studies performed at the Anaesthesia department between 1994 and 1997 were reviewed and seven hypothermic patients with transesophageal echocardiography performed during cardiopulmonary resuscitation were identified.

Results: An open mitral valve or a circumferential reduction in aortic diameter during the compression phase was found in four of seven patients, indicating that primarily an increase in intrathoracic pressure (thoracic pump mechanism) generated forward blood flow. In three patients, mitral valve closure during external chest compression indicated that direct cardiac compression (cardiac pump mechanism) contributed to forward blood flow. Two patients studied during active compression‐decompression cardiopulmonary resuscitation demonstrated enhanced right ventricular filling and aortic valve opening during active decompression of the thorax.

Conclusions: In contrast to normothermic arrest victims, an open mitral valve during external chest compression is a common finding during hypothermia, indicating that thoracic pump mechanism is important for forward blood flow during cardiopulmonary resuscitation in hypothermic arrest victims. Aortic valve opening in two hypothermic arrest victims suggests forward blood flow also during active decompression of the thorax with the Cardiopumpr̀.
Effects of isoflurane on oxygenation during one‐lung ventilation in pulmonary emphysema patients
Authors: Satoh D. , Sato M. , Kaise A. , Hagiwara Y. , Saishu T. , Hashimoto Y.
Published: January 2009

Background: Hypoxic pulmonary vasoconstriction has an important role in human one‐lung ventilation (OLV) in the lateral decubitus position under general anesthesia. During OLV, inhalational anesthesia may inhibit hypoxic pulmonary vasoconstriction and the decrease in arterial oxygenation. We studied the effect of isoflurane administration on arterial oxygen tension in chronic obstructive pulmonary disease patients.

Methods: Ten patients who had thoracoscopic laser ablation of bullous emphysema were studied. Patients received 2% isoflurane in oxygen from induction until the first 20 min of OLV in the lateral decubitus position, then were switched to 1% isoflurane lasting 20 min and next were switched to 0.5% isoflurane lasting 20 min. After each 20‐min inhalation, pulmonary and hemodynamic parameters were measured. The given concentrations for isoflurane were merely vapor meter concentrations.

Results: PaO2/FIO2, Qs/Qt respiratory rate peak inspiratory pressure and PaCO2 showed no significant changes at each point of isoflurane. Expiratory tidal volume significantly decreased (P<0.05) with 0.5% isoflurane compared to that with 2% isoflurane. Cardiac output, mean arterial pressure, mean pulmonary arterial pressure, systemic vascular resistance and pulmonary vascular resistance showed no significant changes at each point of isoflurane.

Conclusions: In patients with pulmonary emphysema, arterial oxygenation is not affected by low isoflurane concentration during OLV in the lateral decubitus position.
Effects of recruitment of collapsed lung units on the elastic pressure–volume relationship in anaesthetised healthy adults
Authors: Svantesson C. , Sigurdsson S. , Larsson A. , Jonson B.
Published: January 2009

Background: The elastic pressure–volume (Pel–V) curve of the respiratory system can be used as a guide for improved ventilator management. The understanding of curves recorded for sick patients can be improved with better knowledge of the Pel–V relationship observed in healthy humans. Dynamic Pel–V curves were determined over an extended volume range in 15 anaesthetised and muscle‐relaxed healthy humans. The influence of a recruitment manoeuvre was studied.

Methods: Dynamic Pel–V curves were determined during a single prolonged insufflation before and after the recruitment manoeuvre. A mathematical three‐segment model of the curve including a linear intermediate segment, delineated by the lower (LIP) and upper (UIP) inflection points, was used for characterisation of the recorded curves.

Results: The model gave an adequate description of the recorded Pel–V curves. Before the recruitment manoeuvre, compliance increased until the LIP was reached at 20 cm H2O (1.9 L). Then followed a long linear segment. After the recruitment manoeuvre, compliance increased during insufflation until a LIP was reached at 13 cm H2O (1.2 L). Above the LIP followed a shorter linear segment (compliance = 140 mL/cm H2O) and then an upper segment with decreasing compliance.

Conclusion: Pel–V curves recorded before and after the recruitment manoeuvre show that large lung compartments close during anaesthesia and that high pressures are needed to achieve recruitment even in the normal lung. Accordingly, the LIP does not define the end of recruitment during insufflation.
A possible increase in plasma norepinephrine by removal of the liver
Authors: Irita K. , Okamoto H. , Sakaguchi Y. , Takahashi S.
Published: January 2009

Background: It has recently been suggested that the human liver plays an important role in clearing plasma norepinephrine, especially in restricting most of the norepinephrine to reach the systemic circulation from the gut.

Methods: We examined the changes in plasma catecholamine levels in a patient undergoing extracorporeal hepatic resection and 4 patients undergoing living‐related orthotopic liver transplantation.

Results: While the changes in plasma epinephrine levels were not necessarily consistent with the proposal that plasma catecholamine levels increase during the anhepatic period, plasma norepinephrine did show a transient increase in accordance with the anhepatic period in all cases. Although we could not rule out the increase in the inflow rate of norepinephrine into plasma, the interrupted hepatic elimination of norepinephrine, especially released from the gut, seemed to be partly responsible for the anhepatic period‐associated increase in plasma norepinephrine.

Conclusion: The present finding might have the potential to improve perioperative management of patients undergoing extracorporeal hepatic resection and orthotopic liver transplantation.
Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?
Authors: Nijs N. , Duvaldestin P. , Slavov V. , Dhonneur G.
Published: January 2009

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect.

Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg−1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg−1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg−1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train‐of‐four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus.

Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min).

Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium‐induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.
Thoracoscopic microsurgical technique for vertebral surgery – anesthetic considerations
Authors: Lischke V. , Westphal K. , Behne M. , Wilke H. J. , Rosenthal D. , Marquardt G. , Kessler P.
Published: January 2009

Background: The thoracoscopic microsurgical technique (TMT) for vertebral and spinal cord surgery is associated with the benefits of reduced postoperative pain, accelerated return to physical activity and reduced complication rates. However, because of the surgeon's requirement of a non‐ventilated lung, it confronts the anesthesiologist with the need for extremely long duration of single‐lung ventilation (SLV).

Methods: We describe our experiences with 82 patients, whom we anesthetised from 1993 until 1996 for TMT. Because of the potential risk of depression of hypoxic pulmonary vasoconstriction during SLV by volatile anesthetics, we primarily used a total intravenous technique (55 patients). With more experience, we also used a combination of volatile and intravenous anesthetics (16 patients) and, finally, volatile anesthetics only (11 patients). Data from patients anesthetised for TMT were compared with data from 22 patients operated with open thoracotomy from 1984 until 1992.

Results: While the operating time (290.1±133.2 min for TMT vs. 312.3±113.6 for thoracotomy) and the anesthesia time (431.2±140.3 for TMT vs. 416.4±102.1 for thoracotomy) showed no significant differences, the TMT required an extremely long time of SLV (270.2±133.2 min) to gain access to the spine using left‐sided double‐lumen tubes. While the oxygenation index (PaO2/FiO2), as a marker for pulmonary oxygenation capacity, decreased significantly after initiation of SLV for TMT, it was markedly enhanced with increasing duration (270.2+133.2 min) of SLV. Oxygenation index showed no significant difference when comparing the different anesthetic techniques for TMT.

Conclusion: We conclude that despite the long duration of SLV, TMT is a reasonable alternative to open thoracotomy for thoracic neurosurgical spine procedures because of the substantial clinical benefits of accelerated return to physical activity, reduced complication rates and reduced intensive care unit and hospital stay.
Effect of learning during an anaesthesiological multicentre trial
Authors: Honkavaara P. , Paloheimo M.
Published: January 2009

Background: After the completion of a multicentre study, it was disputed whether becoming acquainted with a novel drug would affect dosing, and how many consecutive patients would be sufficient for this phenomenon.

Methods: A post hoc analysis of the data on 408 patients from a multicentre study on propofol was performed to reveal a possible learning effect. For study purposes, the patients were given consecutive anaesthetic serial numbers per anaesthesiologist. Patients eligible for the study with serial numbers 3–8 (113) were included in the initial group, and numbers 12–17 (89) in the end group.

Results: The patients in the end group opened their eyes (4.1 vs. 5.5 min, P<0.05), gave their date of birth (4.5 vs. 6.3 min, P<0.005) and walked sooner (27.1 vs. 49.8 min, P<0.05) than the patients in the initial group. They received a higher dose of propofol at induction (2.37 vs. 2.26 mg kg‐1, P<0.05) and the last additional dose of propofol earlier (3.3 vs. 2.7 min, P<0.05).

Conclusion: This study shows that the learning effect can influence the results in a multicentre study. Learning contamination may occur if a novel drug is dosed by clinical judgement, and if the allocation of patients into groups is markedly uneven during the different stages of the study.
Subarachnoid and intravenous PCA versus bolus administration for postoperative pain relief in orthopaedic patients
Authors: Rundshagen I. , Kochs E. , Standl Th. , Schnabel K. , Esch J. Schulte am
Published: January 2009

Background: Patient‐controlled analgesia (PCA) with intravenous piritramide and subarachnoid bupivacaine was studied during postoperative pain management in comparison with nurse‐administered bolus injections.

Methods: Following general anaesthesia (n=60) patients randomly received either 3.75–7.5 mg i. v. piritramide on demand (group P‐Bolus) or via PCA (group P‐PCA; initial bolus: 3.75 mg i. v. piritramide, baseline rate: 1 mg/h, demand‐dose 1.5 mg, lockout time: 20 min). Following continuous spinal anaesthesia (n=60; CSA; 28‐G spinal catheter) patients randomly received a subarachnoid injection of 1.5 ml bupivacaine 0.25% every 2–4 h (group B‐Bolus) or a baseline infusion of 0.5 ml/h bupivacaine 0.125% plus 0.5 ml bupivacaine 0.125% on demand via PCA (group B‐PCA; lockout time: 30 min). Pain ratings were assessed hourly by patients using a visual analogue scale (0=no pain, 100 mm=unbearable pain). Statistics: multivariate analysis of variance.

Results: While pain scores did not differ between group P‐Bolus and P‐PCA, group B‐PCA showed the lowest pain ratings (18±22 mm) differing significantly from group B‐Bolus (41±32 mm: P<0.001). Group P‐PCA required more piritramide than group P‐Bolus (46±15 mg vs. 31±13 mg, P = 0.001). In contrast group B‐PCA required less bupivacaine than group B‐Bolus (18±4 vs. 23±7 mg, P=0.002).

Conclusion: PCA with CSA was more effective than nurse‐administered bolus‐administration of bupivacaine, while the present study failed to show superiority of i. v. PCA over i. v. bolus‐administration of piritramide. PCA using the subarachnoid route is a promising concept for treatment of postoperative pain in orthopaedic patients, while the PCA piritramide regime of this study warrants improvement.
The accuracy and precision of four infrared aural canal thermometers during cardiac surgery
Authors: Imamura M. , Matsukawa T. , Ozaki M. , Sessler D. I. , Nishiyama T. , Kumazawa T.
Published: January 2009

Background: Four infrared aural canal thermometers are currently available in Japan: Geniusr̀, Thermoscanr̀, Quickthermor̀, and Thermopitr̀. We therefore tested the hypothesis that each is sufficiently accurate and precise for clinical use.

Methods: For the purpose of this investigation, we considered accuracy to be the mean difference between the test thermometers and the reference thermocouple. Precision was considered to be the standard deviation of the difference between the test and reference values. We evaluated ten patients undergoing cardiopulmonary bypass with moderate hypothermia (≅30°C). Aural canal temperatures were measured in random order with each infrared thermometer, and compared with readings from a thermocouple positioned at the contralateral tympanic membrane.

Results: Compared to the thermocouple, the Geniusr̀ and Thermoscanr̀ both had regression slopes >0.85 and correlation coefficients near 0.87; in contrast, slopes of the Quickthermor̀ and Thermopitr̀ regressions were 0.68 and 0.53, respectively. The correlation coefficients for each were <0.65. The accuracy (offset, or bias) was near 0°C with both the Geniusr̀ and Thermoscanr̀ thermometers. In contrast, it was 1.1°C with the Quickthermor̀ and a full 2.3°C with the Thermopitr̀. The precision (standard deviation) of the measurements, however, was ≅0.8°C in each case.

Conclusion: We conclude that none of the tested aural canal infrared thermometers was sufficiently accurate and precise for perioperative use.
Catheter‐induced thrombus in the superior vena cava diagnosed by transesophageal echocardiography
Authors: Weber T. , Huemer G. , Tschernich H. , Kranz A. , Imhof M. , Sladen R. N.
Published: January 2009

Background: To present the role of transesophageal echocardiography (TEE) in the diagnosis and management of catheter‐related superior vena cava thrombosis.

Case history: A 42‐year‐old woman with severe Crohn's disease presented with septic shock and pulmonary embolism three weeks after emergency laparotomy and ileocolic resection for small‐bowel perforation with peritonitis. Cardiopulmonary evaluation with ECG, pulmonary artery catheter and TEE demonstrated no evidence of acute myocardial ischemia or ventricular dysfunction; hemodynamic indices were consistent with severe sepsis. TEE revealed a large sheathing thrombus surrounding a central venous catheter used for parenteral nutrition. A spiral CT scan of the chest confirmed multiple peripheral pulmonary emboli. Treatment consisted of systemic anticoagulation and antibiotics. To avoid further pulmonary embolism, the central venous catheter was not removed until six days later under TEE monitoring, which revealed that the thrombus was firmly adherent to the superior vena cava. The patient made an uneventful recovery and was discharged from hospital on long‐term anticoagulant therapy.

Conclusion: In a case of catheter‐induced superior vena cava thrombosis with septicemia and pulmonary embolism, bedside TEE was very helpful to make the correct diagnosis early, assess thrombus size during anticoagulation, and monitor cardiac performance and thrombus disposition during central venous catheter removal.
Preoperative oral granisetron prevents postoperative nausea and vomiting
Authors: Fujii Y. , Tanaka H. , Toyooka H.
Published: January 2009

Background: Postoperative nausea and vomiting (PONV) is a commonly observed adverse effect of anaesthesia. This study was designed to evaluate the efficacy of granisetron administered orally for preventing PONV in female patients undergoing major gynaecological surgery.

Methods: In a prospective, randomized, placebo‐controlled, double‐blind study, 120 patients received orally either placebo or granisetron (1 mg, 2 mg or 4 mg) (n=30 for each) 1 h before surgery. The same standard general plus regional anaesthetic technique was employed throughout. Postoperatively, during the first 24 h after anaesthesia, the incidence of PONV and adverse events was recorded by nursing staff.

Results: The incidence of PONV was 47% with placebo, 37% with granisetron 1 mg, 10% with granisetron 2 mg and 10% with granisetron 4 mg (P<0.05; overall Fisher's exact probability test). No difference in the incidence of adverse events was observed among the groups.

Conclusion: Preoperative oral granisetron in a minimum dose of 2 mg is effective for preventing PONV after major gynaecological surgery.
Dose‐related cardiovascular effects of amrinone and epinephrine in reversing bupivacaine‐induced cardiovascular depression
Authors: Igarashi T. , Hirabayashi Y. , Saitoh K. , Fukuda H. , Shimizu R. , Mitsuhata H.
Published: January 2009

Background:To ascertain the efficacy of amrinone and epinephrine in reversing bupivacaine‐induced cardiovascular depression, we investigated the time course of recovery of cardiac function with 3 doses of both agents after bupivacaine administration.

Methods:In sevoflurane‐anaesthetized dogs, bupivacaine was infused intravenously at 1 mg . kg−1. min−1until mean arterial pressure fell to 60 mmHg or less. The 3 doses of amrinone (1, 2, and 4 mg . kg−1) or the 3 doses of epinephrine (2, 5, and 10 μg . kg−1) were administered as a bolus in randomized order in each dog.

Results:Amrinone improved maximum left ventriculardP/dt, a time constant of left ventricular isovolemic relaxation and cardiac index persistently and dose‐relatedly. Amrinone increased heart rate and decreased left ventricular end‐diastolic pressure and systemic vascular resistance index. Amrinone at 1 and 2 mg . kg−1significantly increased mean arterial pressure, but amrinone at 4 mg . kg−1did not. Epinephrine increased mean arterial pressure, maximum left ventriculardP/dt, and systemic vascular resistance dose‐relatedly. The duration of action of epinephrine, peaking at 1 min and subsequently decreasing by 10 min after administration, did not differ among the groups. Epinephrine at all doses failed to improve a time constant of left ventricular isovolemic relaxation and cardiac index. ECG evidence of serious ventricular dysrhythmias was seen in 1 out of 6 dogs after administrating each dose of amrinone and in 3, 3 and 5 out of 6 dogs after administrating 2, 5 and 10 μg . kg−1of epinephrine, respectively.

Conclusion:Bolus amrinone may have a certain efficacy in reversing bupivacaine‐induced cardiovascular depression, and improving cardiac contractility and relaxation dose‐relatedly. In contrast to amrinone, bolus epinephrine remains indispensable for resuscitation, causing a rapid, massive, transient and doserelated rise in blood pressure. However, the use of amrinone may be limited predominantly by a decrease in systemic vascular resistance, while the use of epinephrine may be limited predominantly by the generation of serious ventricular dysrhythmias and lack of effectiveness on cardiac index and on cardiac relaxation.
Elevated methemoglobin in patients with sepsis
Authors: Ohashi K. , Yukioka H. , Hayashi M. , Asada A.
Published: January 2009

Background:It has been reported that large amounts of nitric oxide (NO) are released in patients with sepsis. NO is converted to methemoglobin and nitrate. This study was designed to determine whether blood methemoglobin levels were increased in patients with sepsis or septic shock.

Methods:Forty‐five critically ill patients including 8 with sepsis but without shock, 6 with septic shock and 31 non‐septic patients were enrolled in the study. For septic and septic shock patients, blood methemoglobin concentrations were measured during sepsis or septic shock and at the time of recovery or just before the onset of sepsis. For the remaining non‐septic patients, methemoglobin concentrations were measured atICUadmission and discharge.

Results:Blood methemoglobin levels in the presence of sepsis or septic shock were significantly (P<0.05) higher than those in non‐septic patients and those at recovery or just before the onset of sepsis in both septic and septic shock patients.

Conclusions:Blood methemoglobin concentration may be useful as a marker of the onset of sepsis or septic shock.
Correction of pressure waveforms recorded by fluid‐filled catheter recording systems: A new method using a transfer equation
Authors: Lambermont B. , Gerard P. , Detry O. , Kolh P. , Potty P. , D̂Orio V. , Marcelle R.
Published: January 2009

Background: Pressure measuring systems using fluid‐filled catheters can result in the recording of distorted pressure waveforms. It results in phase delay, overestimation of systolic and, to a lesser extent, of diastolic pressure. We designed and evaluated a method to correct this pressure waveform distortion using an appropriate transfer equation obtained from the dynamic response of the fluid‐filled catheter. This transfer equation is based on the principle that a fluid‐filled catheter recording system is considered as an underdamped dynamic system fully characterized by its natural frequency (ωn and damping ratio (ζ).

Methods: Pressure waveforms, simultaneously recorded in vitro or in vivo by a fluid‐filled catheter (Pc) and a micromanometertipped catheter (Pref), were used to validate the method. Dynamic response of the catheter used was obtained from a fastflush test. The corrected signal (Ppred) was obtained using con, Ωnζ and the following transfer equation:

d2Pc/dt2+ 2 ωnζ dPc/dt+ωn2Pc=C Ppred (t)

After correction of Pc, Ppred was compared, using a linear regression, with Pref taken as reference.

Results: Our results showed that Ppred was fitted to Pref with excellent coefficient correlation (0.99). The mean error and the standard error of estimate were respectively –1.16 mmHg and 1.4 mmHg.

Conclusion: This new method can convert the distorted pressure waveforms transmitted by any fluid‐filled catheters into high‐fidelity signals. It suppresses the phase delay and the over‐estimation of systolic pressure induced by fluid‐filled catheters.
Postoperative analgesia with epidural bupivacaine and low‐dose fentanyl ‐ a comparison of two concentrations
Authors: Sjöström S. , Bläss J.
Published: January 2009

Background: The purpose of the study was to compare the analgesic and side effects of two epidurally administered mixtures of bupivacaine and fentanyl with the same drug ratios.

Methods: One hundred patients scheduled for colorectal surgery were randomized to receive a thoracic epidural infusion of either bupivacaine 0.12% with fentanyl 2 μg/ml or bupivacaine 0.24% with fentanyl 4 μg/ml during 48 h postoperatively. The pumps were adjusted to keep the visual analogue scale (VAS) pain score at 3 or less (on a scale of 0–10) with a minimum of adverse effects.

Results: There were no statistically significantly differences between the two groups in VAS pain scores. The average VAS pain score resting varied between 0.5 and 1, and coughing between 1.9 and 3.4. One case of respiratory depression with breathing frequency 7 occurred in each group, but none of the patients required naloxone. One patient in the low concentration group developed partial motor weakness in both legs 36 h postoperatively. Equal drug amounts ‐ bupivacaine 10.8–11 mg/h and fentanyl 18‐18.4 μg/h ‐ were given in both groups throughout the study.

Conclusions: Both groups had low pain scores with few and comparable adverse effects. It thus seems that the volume is not important when mixtures of bupivacaine and fentanyl in the studied concentrations are infused epidurally at a low thoracic level. Practical reasons favour the higher concentration mixture.
Porcine‐derived surfactant treatment of severe bronchiolitis
Authors: Luchetti M. , Casiraghi G. , Valsecchi R. , Galassini E. , Marraro G.
Published: January 2009

Background: It is hypothesized that surfactant treatment helps to improve severe bronchiolitis by restoring surfactant system activity. This study aims to assess the effect of surfactant on gas exchange, peak inspiratory pressure and duration of mechanical ventilation and intensive care unit (ICU) stay in children with severe bronchiolitis.

Methods: Twenty children with bronchiolitis requiring mechanical ventilation were randomly assigned to one of two groups (10 patients each). Group A was treated with continuous positive pressure ventilation (CPPV) plus surfactant. Group B was treated with CPPV only. Porcine‐derived surfactant, 50 mg/kg body weight, was instilled into the trachea. Arterial tension of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio, arterial tension of carbon dioxide (PaCO2), and peak inspiratory pressure (PIP) were assessed. Heart rate and non‐invasive arterial blood pressure were monitored. The duration of CPPV and the length of ICU stay were also recorded. Finally, the incidence of complications and the survival rate were assessed.

Results: In group A, the PaO2/FiO2 ratio significantly improved from 1 h and a reduction in PaCO2 was noted from 12 h. A reduction of PIP was observed from 3 h. The duration of CPPV and the length of ICU stay were reduced in group A. No complications were reported in either group and all children survived.

Conclusions: Surfactant treatment of severe bronchiolitis appeared to improve gas exchange, reduce PIP and shorten CPPV and ICU stay. However, these initial results must be confirmed by a larger and more rigorously controlled study.
Preservation of humidity and heat of respiratory gases in spontaneously breathing, tracheostomized patients
Authors: Thomachot L. , Viviand X. , Arnaud S. , Vialet R. , Albanese J. , Martin C.
Published: January 2009

Background: Ventilation with endotracheal intubation bypasses the upper airway and the normal heat and moisture exchanging process of inspired gases. A continuous loss of moisture and heat occurs and predisposes patients to serious airway damage. We therefore prospectively studied one heated humidifier system, one cold humidifier system and one heat and moisture exchanger in spontaneously breathing, tracheostomized intensive care unit patients to determine the ability to preserve patients' heat and water.

Methods: Following a randomized order, 10 patients were spontaneously ventilated for 24‐h periods with the Nam 35r̀ humidifier (Europe Medical, France, a cold water humidifier), the heat and moisture exchanger Trach‐Ventr̀ (Gibeck, Sweden), and the Aerodyner̀ humidifer (Kendall, USA). In each patient, during the inspiration phase, the following measurements were performed: mean values of temperature and relative humidity of inspired gases. The absolute humidity was calculated. Values were obtained in each patients after 40 min and 24 h.

Results: The Trach‐Ventr̀ filter and the Aerodyner̀ humidifier had better humidification and thermic capacities than the Nam 35r̀ humidifier (P<0.001). With the Nam 35r̀ humidifier, no patient had temperature of inspired gas >29°C. Concerning absolute humidity of inspired gases, the Nam 35r̀ humidifier achieved a lower performance than the other two tested systems (P<0.001).

Conclusion: In spontaneously breathing, tracheostomized intensive care unit patients, the Trach‐Ventr̀ heat and moisture exchanger and the Aerodyner̀ heated system achieved satisfactorily preservation of heat and humidity of inspired gases.
Inhibited hypothalamic histamine metabolism during isoflurane and sevoflurane anesthesia in rats
Authors: Hashimoto Y. , Hashimoto Y. , Hirota K. , Matsuki A.
Published: January 2009

Background: Histamine is most densely distributed in the hypothalamus and has an important effect on consciousness or wakefulness. It has been little considered whether general anesthetics could exert their effects on hypothalamic histamine metabolism. The present study was conducted to investigate the effects of isoflurane and sevoflurane anesthesia on hypothalamic histamine metabolism.

Methods: Sixty male Wistar rats were divided equally into isoflurane and sevoflurane anesthesia groups. Each group was divided into three equal sub‐groups: the control, anesthesia and recovery groups. The rats of the anesthesia and recovery groups were exposed to either 2% isoflurane or 3% sevoflurane for 30 min. The recovery group was kept in air for 30 min after anesthesia. The rats were decapitated to dissect out hypothalamus which was divided into the fore and rear portion. The contents of histamine and 1‐methylhistamine, which is a main histamine metabolite, were determined by high‐performance liquid chromatography. The obtained data were analyzed by one‐way analysis of variance followed by Bonferoni's test.

Results: Histamine contents of the anterior and posterior hypothalamus in both isoflurane and sevoflurane groups increased significantly during the anesthesia and 1‐methylhistamine contents of the anterior and posterior hypothalamus in sevoflurane group increased remarkably after anesthesia. The increases of histamine contents supposedly reflected inhibited histamine metabolism and the increases of 1‐methylhistamine would be caused by acceleration of histamine degradation.

Conclusions: Histamine metabolism was inhibited during both isoflurane and sevoflurane anesthesia and accelerated only in the posterior hypothalamus during the emergence from these anesthetics.
Waste gas exposure during desflurane and isoflurane anaesthesia
Authors: Hobhahn J. , Hoerauf K. , Wiesner G. , Schrögendorfer K. , Taeger K.
Published: January 2009

Background: Currently, there are no data available concerning the occupational exposure to desflurane during general anaesthesia. This prospective, randomized study reports on occupational exposure to desflurane, compared to isoflurane, in a modern operation theatre (OT).

Methods: The study was performed in an OT equipped with a modern air‐conditioning system and with a low‐leakage anaesthesia machine connected to a central scavenging system. Trace concentrations of the anaesthetics were measured continuously by means of a photoacoustic infrared spectrometer during general anaesthesia in 30 patients undergoing eye surgery. Values were obtained within the breathing zone of the anaesthetist, the surgeon, the auxiliary nurse and at the mouth of the patient.

Results: Desflurane and isoflurane were administered with median (range) endtidal concentrations of 4.7 (3.8–10.3) vol% and 0.9 (0.6–1.4) vol%, respectively. The personnel‐related median values of the average trace concentrations of desflurane and isoflurane were 0.5 (0.01–7.5) ppm and 0.2 (0.01–1.6) ppm, respectively.

Conclusions: Occupational exposure to desflurane is low in the environment of a modern OT, even though it has to be administered in approximately 5‐fold higher concentrations compared to isoflurane.
Intravenous endotoxin does not increase tissue extravasation of albumin in rats
Authors: Metcalf K. , Sundqvist T. , Lisander B.
Published: January 2009

Background: It is unclear whether activation of the inducible nitric oxide synthase (iNOS) increases or decreases the extravasation of plasma.

Methods: Chloralose anaesthetised male Wistar rats receivedE. colilipopolysacharide (LPS), 3 mg kg‐1i.v., or the corresponding volume of saline, 3 or 5 h before the end of the experiment. Mean arterial pressure (MAP) and heart rate (HR) were recorded. Tissue clearance of radio‐labelled albumin, during the last 2 h of each experiment, was determined by a double‐isotope method. In separate animals, the serum concentration of nitrite and nitrate was determined, 5 h after LPS or the solvent.

Main Results: LPS initially decreased MAP and lastingly increased HR. In the 3‐h LPS animals (n=8), tissue plasma clearance was lower in the heart and calf muscle and increased only in diaphragm, compared to corresponding control animals (n=8). In the 5‐h LPS rats, clearance was lowered (n=8) in the entire gastrointestinal tract and in testes, compared to controls (n=8). The serum nitrite/nitrate concentration was higher in animals given LPS (n=6) than in controls (n=6).

Conclusion: After LPS, tissue clearance of albumin was not increased in any major tissue, in spite of increased serum levels of NO end products. Apparently, after activation of iNOS, the augmented release of NO is not necessarily associated with increased albumin extravasation.