bluuebunny/crossref_metadata_2025 huggingface dataset:
Does morphine premedication influence the pain and consumption of postoperative analgesics after total knee arthroplasty?
Authors: Hendolin H. , Nuutinen L. , Kokki H. , Tuomisto L.
Published: January 2009

Evidence of pre‐emptive analgetic effect of opioid would offer great potential benefit to patients with postoperative pain, a better pain relief with less opioid. The aim of this double blind randomised trial was to study the effect of intramuscular morphine premedication on postoperative pain.

Forty‐one patients undergoing total knee arthroplasty were randomly allocated to four groups. Two groups received epidural morphine, 4 mg immediately after operation and 3 mg ten hours later, and two groups the same volume of saline. All patients had access to intravenous PCA‐fentanyl. One epidural morphine and one epidural saline group (PreEpiMo and PreMo, respectively) received morphine, 0.14 mg/kg i.m. as premedication. Pain was measured with a visual analogue scale (VAS). Respiration was monitored by means of pulseoximetry, arterial blood gas analysis and rate of breathing.

Morphine premedication reduced postoperative pain in the immediate postoperative period in patients with epidural placebo (PreMo), hut the effect was absent in patients with PreEpiMo. Epidural morphine (EpiMo) provided stable analgesia with reduced need of PCA‐fentanyl. Two patients (10%) (one in EpiMo and one in PreEpiMo) developed respiratory depression requiring naloxone treatment. The dosage of epidural morphine used in this study was a likely explanation of this depression. Nausea, vomiting, itching and urinary retention were the most frequent side effects without significant differences between the groups. In conclusion, morphine premedication had a temporary rest effect on the postoperative pain. Epidural morphine provides a better analgesia than intravenous PCA‐fentanyl.
Differential effects of pre‐treatment with intrathecal or intravenous morphine on the prevention of spinal cord hyperexcitability following sciatic nerve section in the rat
Authors: Luo L. , Wiesenfeld‐Hallin Z.
Published: January 2009

The effect of intrathecal (i.t.) and intravenous (i.v.) morphine on spinal hyperexcitability following unilateral section of the sciatic nerve was studied in decerebrate, spinalized, unanesthetized rats. Sciatic nerve section evoked a biphasic, prolonged hyperexcitability of the flexor reflex. Either i.v. (0.2, 1 or 10 mg · kg‐1) or i.t. (3 or 10 μg) morphine was administered prior to sciatic nerve section. All doses of morphine significantly depressed the baseline flexor reflex and abolished the less intense prolonged second component of reflex hyperexcitability. One and 10, but not 02, mg · kg‐1 i.v. morphine significantly depressed the first phase of spinal cord sensitization. However, both 3 μg and 10 μg i.t. morphine were significantly more effective than i.v. morphine in suppressing spinal cord hyperexcitability. The present results suggest that moderate doses of i.t. morphine decrease spinal hyperexcitability following nerve transection more than even extremely large i.v. doses. The poorer effect of i.v. morphine on preventing spinal hyperexcitability may be due to low spinal concentration after systemic administration.
Retention and distribution of polygeline (Haemaccel®) in the rat
Authors: ØStgaard G. , Onarheim H.
Published: January 2009

The plasma substitute polygeline (Haemaccel®) contains a large fraction of molecules sufficiently small to cross the capillary and glomerular membranes. Plasma volume expansion, tissue extravasation and renal elimination of this artificial colloid were quantified using 125l‐labelled polygeline molecules. In pentobarbital anaesthetized rats, either 10 ml 3.5% polygeline (n=8) or 10 ml 0.9% saline (n=8) was infused intravenously over 60 min. The plasma volume was assessed by the 3 min distribution volume for 131l‐albumin and the plasma volume changes over time were calculated from erythrocyte volume fractions. The plasma volume increased by 4.6 (2.0) ml (mean (SD)) at the end of the Haemaccel infusion compared with 2.1 (1.8) ml after the saline infusion (P=0.02). One hour later the increase was 2.4 (1.5) and 1.6 (1.0) ml respectively, not significantly different (P=0.20). Extravasation of labelled polygeline was greatest in the kidney, possibly due to cellular uptake. Skin and skeletal muscle contained 4–5 times more polygeline than could be attributed to intravascular radioactivity, but still uptake in these tissues did not reach one percent of the amount injected. Following a 60 min infusion and a 60 min interval, 23 (4)% of the polygeline was recovered intravascularly, 43 (9)% had been excreted in urine, leaving 33% to other compartments. Thus, more polygeline was distributed to the interstitium than remained in the circulation. This calls for further investigations into the handling and effect of polygeline in this extravascular compartment.
Decrease in plasma volume from intra‐abdominal trauma in rats is prevented by H1 but not by H2 histaminergic blockade
Authors: Larmark M. , Lisander B.
Published: January 2009

Intra‐abdominal surgery causes plasma extravasation which, in the rat, is prevented by combined histaminergic H1 and H2 blockade. We evaluated the relative importance of H1 and H2 blockade in this situation.

Cloralose‐anaesthetized Wistar rats were subjected to a standardized abdominal trauma. Mean arterial pressure (MAP), heart rate (HR) and haematocrit (Hct) were monitored and plasma volume (PV) was determined before and 1 h after the trauma.

Compared to non‐traumatized rats (n=8), the trauma decreased PV and increased Hct (n=8). MAP decreased during the actual trauma, whereas HR remained stable throughout. In animals given cimetidine 25 mg kg‐1 i.v. just prior to the trauma (n=8), PV, Hct and MAP changed, as in the non‐blocked rats. In contrast, pyrilamine, 10 mg kg‐1 completely prevented the decrease in PV and the increase in Hct (n=7), but not the decrease in MAP.

The findings suggest that a histaminergic HI mechanism is of importance for the plasma loss elicited by intra‐abdominal trauma.
Rapidly progressive pulmonary artery hypertension and end‐stage liver disease
Authors: Mortier E. , Ongenae M. , Poelaert J. , Blauwen N. den , Decruyenaere J. , Aken J. van , Rolly G.
Published: January 2009

Pulmonary hypertension is a recognized but unusual complication of liver disease. It can complicate the perioperative course of liver transplantation. Mild to moderate pulmonary hypertension is generally well tolerated during the procedure and does not appear to contribute to mortality.

Since the pulmonary vascular disease may progress rapidly, it may have advanced to the point of irreversibility at the time of surgery. So, patients with known moderate pulmonary hypertension should have pulmonary arterial catheterisation immediately prior to transplantation. If pulmonary artery hypertension has become severe, then a preoperative trial of vasodilators is warranted. If this fails, the procedure should be cancelled.

We present a patient with alcoholic liver cirrhosis in whom a rapidly progressive pulmonary hypertension made liver transplantation impossible.
Rupture of the stomach caused by manual ventilation during laryngospasm
Authors: Larsen K. M. , Laursen R. J.
Published: January 2009

We report a case, in which laryngospasm developed due to a failed intubation under sedation. During ventilation tension pneumoperitoneum developed resulting in cardiac and respiratory failure. Laparotomy revealed two tears on the lesser curvature of the stomach. Factors influencing stomach rupture are discussed.
High‐dose fentanyl does not suppress interleukin‐1β‐induced increases in plasma ACTH and corticosterone in rats
Authors: Numai T. , Inaba H.
Published: January 2009

Background. High‐dose fentanyl anesthesia is reported to attenuate the metabolic and endocrinal responses to surgery. Interleu‐kin‐1 (II‐1) is one of the key mediators in the immunono‐neuroendocrine system, and may be involved in the stress responses to surgery. We studied whether high‐dose fentanyl may influence the II.‐1β‐induced alterations in plasma ACTH and corticosterone in rats.

Methods. Plasma ACTH, corticosterone, blood pressure, heart rate and acid‐base status were determined in either awake or fentanyl‐anesthetized animals immediately before and after either phosphate buffered saline or IL‐1β administration. Fentanyl anesthesia was induced by bolus intravenous injections of fentanyl at 50 μg/kg and pancuronium bromide at 0.2 mg/kg, and maintained by continuous administrations of fentanyl at 100 or 200 μg·kg‐1·h‐1 and pancuronium bromide at 0.4 μg·k‐1·h‐1.

Results. In awake rats, IL‐lβ at incremental doses of 0.25, 0.5 and 1 μg/kg increased plasma ACTH in a dose‐dependent manner, but heat‐inactivated IL‐1β at 4 μkg did not influence plasma ACTH. A noxious stimulus with tail clamping for 30 min did not significantly alter plasma ACTH in fentanyl‐anesthetized rats. Fentanyl reduced the basal plasma corticosterone, but it did not modulate the increases in plasma ACTH and corticosterone after the administration of IL‐1β at 1 μg/kg. Fentanyl moderately increased the basal blood pressure and heart rate, but it moderately attenuated the IL‐1β‐induced elevations of blood pressure and heart rate. IL‐1β moderately decreased PCO2 in awake animals.

Conclusions. Fentanyl anesthesia, which is able to suppress the endocrine responses to noxious stimuli, does not attenuate the IL‐1β‐mediated activation of the pituitary‐adrenal axis in rats.
Effects of posture and pneumoperitoneum during anaesthesia on the indices of left ventricular filling
Authors: Gannedahl P. , Odeberg S. , Brodin L.‐Å. , Sollevi A.
Published: January 2009

Background. Laparoscopic surgery requires the use of pneumoperitoneum (PP). When combined with positional changes, pneumoperitoneum may cause marked circulatory alterations.

Methods. Eight anaesthetized cardiovascularly healthy patients, scheduled for laparoscopic cholecystectomy, were studied before and during pneumoperitoneum in three different postures (supine, Trendelenburg and reversed Trendelenburg), employing transesophageal echocardiography and pulmonary artery pressure monitoring.

Results. PP significantly increased end‐diastolic area (EDA) and pulmonary capillary wedge pressure (PCWP) irrespective of posture. PCWP was significantly influenced by postural changes, whereas EDA was not. Further, changes in EDA and PCWP covaried during the investigation, but showed no linear correlation. Systolic function, measured as end‐systolic area (ESA) and fractional area shortening (FAS), was not altered. Diastolic function, as assessed by the velocity rate of the trans‐mitral flow during the early filling phase (E) and the atrial contraction (A), showed no change of the E/A ratio, whereas after the induction of PP there was a significant reduction of the E component.

Conclusions. In cardiovascularly healthy patients, the left ventricular volume is increased during pneumoperitoneum. Further, changes in invasive pressure determinations (PCWP) do not correlate linearly with changes in volume indices of left ventricular filling (EDA).
Are neurologic events occurring during carotid artery surgery predictive of postoperative neurologic complications?
Authors: Walleck P. , Becquemin J. P. , Desgrances P. , Bonnet F.
Published: January 2009

Background. Per‐ and postoperative neurologic complications occurring during carotid artery surgery may be related to different mechanisms. Nevertheless, recent studies suggest that they are related and that patients who develop reversible neurologic events peroperatively are at risk of postoperative neurologic complications. We, therefore, studied 265 patients operated under regional anaesthesia to assess the incidence and the pathogenesis of per‐ and postoperative neurologic disorders and their relationship.

Method. Neurologic function was adequately assessed in 261 patients during surgery. The operation was uneventful in 234 patients, while 27 suffered from transient ischaemic neurologic deficit occurring mainly during carotid artery clamping.

Results. Postoperative neurologic complications occurred in 6 (2.5%) of the patients who were symptom‐free during surgery and in 1 (3.7%) of the patients who experienced neurologic deficit during surgery (NS). In this group, two additional patients had peroperative neurologic deficit which lasted a few hours postoperatively so that the total incidence of postoperative neurologic deficit (11.1%) was significantly higher than in the other group (P < 0.05). Emboli (N=3) and carotid artery thrombosis (N=3) were the main causes of postoperative neurologic deficit.

Conclusion. We conclude that patients who have suffered from a peroperative neurologic complication were more frequently in an unstable neurologic condition postoperatively. However, the incidence of “new” neurologic deficit, separated by a free interval from the one occurring peroperatively, was not significantly different in this group.
Control of body temperature during abdominal aortic surgery
Authors: Gregorini P. , Cangini D.
Published: January 2009

Background. Careful control of body temperature during anesthesia aims to prevent cardiocirculatory complications during the phase of recovery from anesthesia. Numerous studies have examined methods for warming the gases breathed by the patient, but the question of whether low flow anesthesia or heat and moisture exchangers can also influence the pattern of body temperature remains unresolved.

Methods. In this clinical trial we evaluated the mean body temperature profile measured at five points in 40 patients divided into two groups: Group I was ventilated with a non‐rebreathing circuit and Group II was ventilated with a circle system using low flow rates of fresh gases. All patients were treated with a hydrophobic heat moisture exchanger.

Results. The results point out a significantly (P < 0.01) lower decrease in mean body temperature 40 min after the start of mechanical ventilation with the use of low flow rate anesthesia.

Conclusions. This study shows that anesthesia carried out using low fresh gas flow rates and heat moisture exchanger is able to reduce the fall in mean body temperature, when compared with anesthesia carried out using high fresh gas flow rates and heat moisture exchanger.
The laryngeal mask airway ‐ anatomical and physiological implications
Authors: Brimacombe J. , Berry A.
Published: January 2009

The laryngeal mask airway (LMA) is a relatively new general purpose airway which fills a niche between the face mask and tracheal tube, both in terms of anatomical location and degree of invasiveness. It sits in the hypopharynx at the interface between the gastrointestinal and respiratory tracts, where it forms a circumferential low pressure seal around the glottis. This has advantages in terms of gas flow through the upper airway and allows direct access to the glottis without loss of airway control. LMA insertion can be considered in the context of swallowing and combines the ability to insert blindly whilst avoiding collision with highly innervated anterior pharyngeal structures. This review deals briefly with the concepts behind LMA design and insertion, and focuses on the anatomical and physiological implications of the LMA with respect to the swallowing reflex, the oesophagus, the pharyngeal mucosa, pulmonary defences, pulmonary mechanics and the cardiovascular system. The possible role of the LMA as a monitor of anaesthetic depth and areas of future research are also discussed.
The efficacy of intrathecal injection of sufentanil using a microspinal catheter for labor analgesia
Authors: Abboud T. K. , Zhu J. , Sharp R. , Lagrange C. , Rosa C. , Kassells B.
Published: January 2009

Intrathecal sufentanil can provide labor analgesia. We investigated the efficacy of multiple injections and the maternal and neonatal effects of intrathecal sufentanil during labor. Seventeen healthy women in active labor received multiple injections of intrathecal sufentanil of 5 μg each through microspinal catheters. Overall maternal satisfaction of analgesia was quantified using 10 cm visual analogue scales and side effects were evaluated. Neonatal outcome was also determined. Onset of analgesia was less than 5 min after the first injection and lasted approximately 148 min. Tolerance developed for the successive injections. The mean onset times were 12.9 and 20.1 min and the durations were 76.6 and 33.9 min for the second and third injections, respectively (P < 0.05). Failure to obtain analgesia developed in all patients after the forth injection. No motor blockade was observed in any of the patients. Mild or moderate pruritus developed in 88% of the patients. Mean systolic blood pressure decreased by a maximum of 11.3% at 30 min and up to 90 min (P < 0.05) after the first injection; three patients required ephedrine treatment. No significant hemodynamic changes were observed after subsequent injections. Five patients experienced transient decrease in sensation. Neonatal status, as evaluated by Apgar scores, Neurological Adaptive Capacity Scores (NACS), fetal heart rate (FHR), and umbilical cord acid‐base status, were within normal limits. Results from our study suggest that multiple small doses of sufentanil administered intrathecally provided satisfactory analgesia for parturients with short duration of labor since acute tolerance developed with multiple injections. High incidence of mild or moderate pruritus was observed during the study. Close attention should be given to hemodynamically unstable patients when this technique is applied.
Decreased coronary blood flow is not responsible for myocardial dysfunction during bupivacaine‐induced cardiotoxicity
Authors: Fujita Y. , Kimura K. , Mihira M. , Yasukawa T.
Published: January 2009

Background. Although previous studies have shown that bupivacaine produces a dose‐dependent vasoconstriction, the possible effects of decreased coronary blood flow on myocardial dysfunction during bupivacaine‐induced cardiotoxicity have not been investigated.

Methods. We carried out the present study using the in situ beating hearts of six beagles. An autoperfusion circuit was established from the left carotid artery to the anterior descending coronary artery (LAD). Its blood flow (QLAD) was measured with an electromagnetic flow meter, and myocardial oxygen consumption was calculated using Fick's principle. Regional myocardial function (systolic shortening: %SS, post‐systolic shortening: %PSS) of the LAD‐supplied region was evaluated by the sonomicrometric technique. While saline or bupivacaine (10 μg/ml) was continuously infused into the LAD in a crossover design, the effects of a vehicle (baseline), acetylcholine (1 and 3 μg/min), nitroglycerin (10 μg/min) and adenosine (10 μg/min) on coronary haemodynamics and regional myocardial function were evaluated.

Results. Bupivacaine caused a decrease in QLAD and regional myocardial dysfunction (a decrease in %SS and an increase in %PSS) at the baseline. While acetylcholine and adenosine increased QLAD with intracoronary bupivacaine‐infusion, regional myocardial dysfunction was not reversed. There was a positive correlation between regional myocardial oxygen consumption and %SS in the whole study.

Conclusions. The results of this study indicate that the decrease in QLAD during bupivacaine‐induced myocardial toxicity is not responsible for regional myocardial dysfunction, and, moreover, that it parallels a decrease in myocardial oxygen demand.
Postoperative complaints after spinal and thiopentone‐isoflurane anaesthesia in patients undergoing orthopaedic surgery Spinal versus general anaesthesia
Authors: Standl T. , Eckert S. , Esch J. Schulte AM
Published: January 2009

Background. The present prospective study investigates the impact of a standardized technique of spinal and general anaesthesia on the incidence and consequences of postanaesthetic complaints dependent on age and sex of patients.

Methods. 433 orthopaedic patients underwent lower limb surgery in spinal (group 1) or general (group 2) anaesthesia. Spinal anaesthesia was performed with 0.5% hyperbaric bupivacaine using a 26‐gauge Quincke needle. General anaesthesia was induced with i.v. injection of thiopentone, fentanyl and atracurium and maintained with 65% nitrous oxide and 1‐1.5 Vol% isoflurane in oxygen. On postoperative day 4, patients were interviewed for onset and duration of postoperative complaints.

Results. The overall incidence of nausea/vomiting (P=0.025) and sore throat (P=0.001) was higher in group 2. In addition, nausea/vomiting was higher in patients between 20 and 60 years in group 2 compared with group 1. While the incidence of urinary dysfunction was higher in men after spinal (P=0.04), nausea/vomiting was more frequent in women after general anaesthesia (P=0.008). Analgetic requirements (P=0.013), time of postoperative surveillance (P=0.042) and frequency of treatment of postoperative complaints (P=0.0001) was higher in group 2.

Conclusion. Spinal anaesthesia was associated with a lower incidence of postoperative complaints and treatments and a shorter surveillance compared to general anaesthesia. Specific complications related to spinal anaesthesia did not depend on age or sex and may allow for recommendation of this technique even in younger and female patients undergoing orthopaedic surgery.
Percutaneous chronic epidural catheterization in the rabbit
Authors: Taguchi H. , Murao K. , Nakamura K. , Uchida M. , Shingu K.
Published: January 2009

Background. Although several epidural catheterizations in small animals have been reported, all of them were performed surgically and no percutaneous method has been reported. We have established a technique for percutaneous chronic epidural catheterization in rabbits.

Methods. Following pentobarbital anesthesia, the animals (n=15) were fixed in a prone position using a fixing apparatus. A 19‐gauge Tuohy needle was inserted in the lumbar region at an angle of about 30° to the skin with the paramedian approach and advanced into the epidural space with the loss‐of‐resistance method. A 23‐gauge Nylon catheter was advanced cephalad in the epidural space and the distal tip was extruded from the neck following the subcutaneous tunnelling. The effects of 0.5 ml of 1% lidocaine injected through the catheter were observed for 10 days.

Results. No behavioral or neurological abnormalities were observed after the catheterization except for one case of catheterization in the epidural vessel. Motor paralysis of hind‐limbs became manifest at 1–2 min after injection of 0.5 ml of 1% lidocaine through the catheter, and lasted 15–25 min. Autopsy revealed that the catheter was located in the lumbar epidural space in all animals and the distribution of methylene blue was consistent with that of lidocaine.

Conclusion. This rabbit model can be used to investigate the effects of epidurally administered drugs.
Effects on complement activation and cytokine (TNF‐α and IL‐8) release of infusion of anti‐TNF‐antibodies or a xanthine derivative (HWA 138) in septic baboons
Authors: Bengtsson A. , Redl H. , Schlag G. , Mollnes T. E. , Högåsen K.
Published: January 2009

Background. Sepsis and septic shock lead to activation of the complement cascade and to the release of pro‐inflammatory cytokines.

Methods. The effects of E coli infusion and of infusion of anti‐TNF antibodies and a xanthine derivative (HWA 138) on complement activation and cytokine release was evaluated in 17 baboons. All animals received 5×108 live bacteria per kg body weight. Five animals received only bacteria, five received in addition 0.5 mg per kg body weight of anti‐TNF‐antibody, and seven received an infusion of 6 mg per kg body weight of HWA 138 in addition to the bacteria.

Results. In baboons receiving 5×108 live E coli per kg body weight increased plasma levels of TCC, TNF‐α and IL‐8 were found. The release of TNF‐α was lower in the group receiving HWA 138 at 2 h after the infusion. In baboons receiving an infusion of anti‐TNF antibody the concentration of IL‐8 was lower at 2 and 4 h than in animals receiving just E coli or HWA 138.

Conclusion. Infusion of anti‐TNF‐antibody before E coli infusion will decrease the formation of IL‐8. Infusion of HWA 138 before the E coli infusion will also inhibit the formation of TNF‐α.
Neutrophil and macrophage activation and anaphylatoxin formation in orthotopic liver transplantation without the use of veno‐venous bypass
Authors: Tomasdottir H. , Bengtson J. P. , Bengtsson A.
Published: January 2009

Background. Activation of neutrophils and activation of complement may be an aetiologic factor behind circulatory insufficiency in association with reperfusion of the grafted liver.

Methods. Neutrophil and macrophage activation (determined as PMN elastase and neopterin release) and complement activation were evaluated in 15 consecutive patients undergoing orthotopic liver transplantation without the use of veno‐venous bypass.

Results. The PMN elastase concentrations were increased at the end ot the anhepatic phase, 2, 5 and 30 min after start of reperfusion and 6 and 24 h postoperatively. There were significantly higher PMN elastase concentrations in patients with circulatory instability (postreperfusion syndrome) compared with those without postreperfusion syndrome. The neopterin concentration was increased 2 min after the start of reperfusion and remained elevated until 6 h postoperatively. The plasma complement C3a concentrations were increased at the end of the anhepatic phase and 2, 5 and 30 min after the start of reperfusion. The plasma C3a levels were higher in patients with postreperfusion syndrome compared to those without.

Conclusions. Activation of neutrophils and macrophages and of the complement cascade with the formation of biologically active substances may be one explanation for the circulatory instability often seen in patients undergoing orthotopic liver transplantation.
In vivo effects of tumor necrosis factor‐a on capillary permeability and vascular tone in a skeletal muscle
Authors: Jahr J. , Grände P.‐O.
Published: January 2009

Background. The present study aims at analysing short‐term effects of TNFα on capillary permeability, on transcapillary fluid fluxes, and on vascular tone in a whole organ cat skeletal muscle in vivo preparation.

Methods. The denervated muscle was isolated from the body but with intact vascular supply. The experimental setup allowed continuous recording of vascular tone, of hydrostatic capillary pressure and tissue volume variations. The capillary filtration coefficient (CFC), which represents the net effect for transcapillary fluid exchange of capillary permeability and number of open capillaries, was calculated before and during intra‐arterial TNF infusion.

Results. We found that TNF had a minor effect on vascular tone in terms of a small vasodilation, and that no effect on hydrostatic capillary pressure could be recorded. CFC increased by 64% during the TNF infusion and this increase must be attributed to an increase in capillary permeability rather than an increase in the number of capillaries available for fluid exchange since the TNF effect on vascular tone is small. This was also supported by TNF‐induced transcapillary filtration.

Conclusions. TNF is a potent drug for increasing capillary permeability causing transcapillary filtration in vivo. Its release, e.g. during sepsis, may therefore contribute to the capillary leakage often seen in this clinical situation.
Unilateral changes of sympathetic tone to the heart impair left ventricular function
Authors: Schlack W. , Thämer V.
Published: January 2009

Background. Different regions within the left ventricle are preferentially supplied by the left or right sympathetic system. In order to characterize different influences of left vs right sympathetic lateralization on LV function, haemodynamic effects of right and left stellate ganglion stimulations (RSGS and LSGS) as well as a right sympathetic block (RSB) were compared.

Methods. Seven α‐chloralose anaesthetized open chest dogs were instrumented for measurement of LV pressure (tip manometers) and regional LV wall thickness (WT, sonomicrometry) in the ante‐ro‐apical wall (AW, innervated by right stellate ganglion) and posterobasal wall (PW, left stellate ganglion). Timing of regional myocardial wall motion was evaluated by the phase of the first Fourier transform of the WT signals, LV asynchrony by the phase difference (ψ) between both regions, and LV diastolic function by the time constant of isovolumic relaxation (τ). Measurements were performed before and after RSB (5 ml of lidocaine 1%); in 6 dogs of this group, RSGS and LSGS (4 V, 0.2 ms, 20 Hz) were performed before RSB. In order to investigate a regional inotropic stimulation without systemic effect, 6 additional dogs received intracoronary noradrenaline injections (NIC, 0.25 μg) into the left circumflex artery perfused myocardium.

Results. LSGS and NIC led to an earlier PW‐motion within the cardiac cycle (phase reduction by 40.0±15.0° (SEM) and 55.5±11. 2°) and RSGS induced an earlier AW‐motion (by 33.7±15.2°). After RSB, AW‐motion was delayed (38.1±9.2°). The consequence was an asynchronous wall motion pattern after all interventions (change in ψ: LSGS ‐64.7±18.7°, RSGS 41.1±15.7°, NIC ‐74.5±17.4°, RSB ‐52.6±14.6°), and a prolonged relaxation (T increase: RSGS 9.4±1.9, NIC 8.3±1.5, RSB 3.7±0.8 ms).

Conclusion. Unilateral increases as well as decreases of sympathetic tone to the heart result in an asynchronous wall motion pattern and an impaired LV relaxation.
Diffusion of anaesthetic gases through different polymers
Authors: Marx T. , Fröba G. , Bäder S. , Villwock J. , Georgieff M.
Published: January 2009

Background. Improvement of working conditions and anaesthesia with closed systems includes reduction of gas leaks during anaesthesia. One source of contamination is the permeation of gases through plastic materials. The volume of gas permeating through a polymer depends on its molecular structure, the solubility and the diffusion coefficient.

Methods. We designed an experimental set‐up to measure the permeation rates of nitrous oxide, enflurane and isoflurane through components of the anaesthetic ventilator made of silicone, latex, rubber and polyvinylchloride (PVC). Reservoir bags, ventilation tubes and endotracheal tubes were investigated.

Results. The highest permeation rates of anaesthetic gases were observed with silicone materials. Permeation through silicone exceeded that of the least permeable material by more than 10.000 times. By summarizing the permeation rates of the single items, the use of silicone increases the anaesthetic system's leakage rate by 4 ml/min, which means an increase of 18% in a modern anaesthetic ventilator and of 31% in a closed system.

Conclusions. The highest permeation rates were found for nitrous oxide through silicone, although nitrous oxide has a known low solubility in plastic materials. The result demonstrates the dependency of the leakage rate on the diffusibility. The leakage of anaesthetic gases caused by silicone items does not alone lead to unacceptable pollution of operating theatres. To minimize the total leakage rates of minimal‐flow‐systems, however, plastic materials with low solubility and low diffusion coefficients have to be used.
Small‐bowel obstruction and the effects of lidocaine, atropine and hexamethonium on inflammation and fluid losses
Authors: Nellgård P. , Jönsson A. , Bojö L. , Tarnow P. , Cassuto J.
Published: January 2009

Background:The profuse fluid losses and morbidity of patients suffering from obstructive ileus are closely related to inflammatory changes in the obstructed bowel wall. Previous experimental studies have shown that use of steroids and NSAIDs can reduce fluid losses in obstructive ileus. In the present study, we investigated the effects of lidocaine on fluid losses since local anesthetics have been shown to possess wide and potent anti‐inflammatory properties. Hexamethonium and atropine were used to study the importance of the autonomic nervous system in bowel obstruction.

Method:Experiments were performed in ratsin vivo. After 18 h of total obstruction of the jejunum by thread ligation, a segment of the obstructed jejunum was placed in a chamber with intact nervous and vascular supply and net fluid transport was continuously, registered by a gravimetric technique. Extravasation of Evans blue albumin as marker of inflammation was quantified by

Conclusion:Lidocaine significantly inhibited or prevented fluid losses when administered intravenously or topically to the obstructed gut. Mechanisms of action could be inhibition of nerve reflexes involved in fluid secretion and by inhibition of inflammation in the bowel wall. The inhibition of fluid losses by hexamethonium further supports the importance of the autonomic nervous system in the pathophysiology of bowel obstruction.
Extracorporeal membrane oxygenation (ECMO) as lung or heart assist
Authors: Bjertnaes L. , Vaage J. , Almdahl S. M. , Lil M. , Nilsen P. A. , Hansen K. , Solbø J. , Jolin Å. , Hotvedt R. , Olafsen K. , Bröndbo A. , Thoner J. , Gilbert M. , Hevrøy O. , Bjørsvik G. , Hesselberg N. , Bergland H. , Sivertsen O.
Published: January 2009

Extracorporeal membrane oxygenation (ECMO) may serve as extracorporeal lung assist (ECLA) in patients with acute respiratory failure (ARF) or as extracorporeal heart assist (ECHA) in patients with low output syndrome (LOS) after open heart surgery. From 1988 to 1992 seven patients underwent ECMO in our hospital; four suffered from ARF and three from LOS. Various bypass techniques were employed. Two ARF patients, aged 58 and 18 years, had veno‐venous bypass; in the latter, ECMO was reinstituted as a veno‐arterial bypass one week after weaning. In a three‐year‐old boy, the ECMO outflow tubing was primarily connected to the pulmonary artery, and shortly afterwards relocated to the common carotid artery. In a 31‐year‐old man with ARF, and three LOS patients, a 56‐year‐old woman, and two men aged 68 and 70 years, ECMO was veno‐arterial with direct access to the ascending aorta. A heparin‐coated system was used, and all but one patient, who was treated with warfarin, received a daily low dose of heparin, which was withdrawn after from one to nine days.

Six patients were weaned off ECMO after 4.5 to 21 days. Three ARF patients recovered completely; the child died. In one LOS patient, ECMO was withdrawn due to a poor general condition. Two others were weaned off ECMO and the intra‐aortic balloon pump, and the inotropic support was significantly reduced, but both died of multiple system organ failure. Although no firm conclusions can be drawn from these few case reports, the heparin‐coated system used as ECLA appears promising, whereas ECHA seems to imply a poor prognosis in patients who are not candidates for cardiac transplantation.
Safety aspects of delivery and monitoring of nitric oxide during mechanical ventilation
Authors: Westfelt U. Nathorst , Lundin S. , Stenqvist O.
Published: January 2009

In the presence of oxygen NO is oxidised to NO2, which is toxic in higher concentrations.

In this technical investigation, we evaluated a dosage system, modified from Stenqvist et al. 1993 (1), regarding NO and NO2 levels. NO was administered before the ventilator and NO2 scavenged using a soda lime absorber in the inspiratory limb close to the ventilator. NO/NO2 levels were measured using fuel cell technique. We tested the duration of soda lime scavenging, put in additional soda lime absorbers, used charcoal as absorber and exchanged tubing material. NO was delivered after the ventilator and we studied effects of interruption of ventilation.

With concentrations of NO at or below 40 parts per million (ppm) at F1O2 0.9, NO2 levels were 1.2 pprn or lower. Corresponding values for 20 and 10 ppm were 0.4 and 0.2 ppm, respectively. Duration of the soda lime absorber was at least 72 hours. Additional soda lime absorbers did not further reduce NO2 levels. Charcoal absorbers reduced NO2, but also NO by 45% from set value. Tubing materials had no influence on NO and NO2 levels. When administering NO at the Y‐piece, levels of NO were increased by 35–60% and NO2 levels by 110–230%, compared to set values.

Oxidation of NO to NO2 is continuously taking place in the breathing system. Doses of up to 40 pprn NO should be considered safe regarding NO2 levels. Administration of NO at the Y‐piece gives high and unpredictable levels of NO2.
Heparin‐coated circuits reduce the formation of TNFα during cardiopulmonary bypass
Authors: Yamada H. , Kudoh I. , Hirose Y. , Toyoshima M. , Abe H. , Kurahashi K.
Published: January 2009

Background: Cardiopulmonary bypass (CPB) causes a systemic intlammatory response. TNFα, which is a major inflammatory mediator, has been found in the circulation during and after CPB. Although previous studies have shown that heparin coating of the extracorporeal circuits reduces complement and granulocyte activation, and the inflammatory response, the possible effect of heparin coating on TNFα formation and the inflammatory response has not been fully investigated.

Methods: Eighteen patients scheduled for coronary artery bypass grafting were divided randomly into two groups. One group of patients had extracorporeal perfusion using heparin coated circuits (HC group, n = 9). The other group had extra‐corporeal perfusion using an identical circuit that was not coated (UC group, n = 9). Blood samples were drawn before, during, and after CPB for measurement of plasma TNFα, plasma IL‐8, neutrophil count, and neutrophil elastase.

Results: Plasma levels of TNFα increased during CPB in the UC group but not in the HC group. Plasma concentrations of IL‐8 increased similarly during and after CPB in both groups. Coating the circuits with heparin did not affect the levels of IL‐8. In both groups, the neutrophil count increased after the release of the aortic cross clamp and remained elevated for three days. In the HC group, however, the increase of neutrophil count was significantly lower compared with the UC group. Plasma concentrations of neutrophil elastase were significantly increased during and after CPB in both groups. However, the levels of elastase were significantly lower at certain time points in the HC group.

Conclusion: From these observations, we conclude that heparin coating of the extracorporeal circuits reduces the TNFα formation during CPB, which may reduce neutrophil activation.
Lidocaine attenuates hyperoxic lung injury in rabbits
Authors: Takao Y. , Mikawa K. , Nishina K. , Maekawa N. , Obara H.
Published: January 2009

Background:High concentrations of oxygen acute lung injury. Neutrophils are thought to play a pivotal role in the pathogenesis of this lung injury through the release of oxygen radicals, neutral proteases, and lysosomal enzymes. Lidocaine has been shown to inhibit neutrophil function. We examined whether intravenous pretreatment with lidocaine attenuated acute lung injury induced by hyperoxia.

Method:Twenty‐seven anaesthetized male rabitts were allocated to receive one of three treatments (n = 9 for each group): ventilation with 100% oxygen for 36 h with and without lidocaine treatment, and ventilation with air for 36 h without lidocaine. In the lidocaine‐treated group, a single intravenous lidocaine 2 mg/kg was administered immediately after the initiation of exposure to 100% oxygen;

Results:Pure oxygen for 36 h caused no significant changes in haemodynamics, lung mechanics, or PaO2/FiO2ratio. However, hyperoxia significantly increased the lung W/D weight ratio, the influx of neutrophils into the lung, and BALF concentrations of C3a, C5a, TNF‐α, IL‐1β, and albumin. Lidocaine attenuated these increases (W/D ratio: 5.7vs5.1, %PMN: 19.2%vs1.6%, C3a: 62 ng/dlvs14 ng/dl, C5a: 7.9 ng/dlvs4.1 ng/dl, TNF‐α: 25 fmol/mlvs2.8 fmol/ml, IL‐1β: 36 fmol/mlvs2.2 fmol/ml, and albumin: 9.5 mg/dlvs2.8 mg/dl, all:P<0.05). The chemiluminescence was increased in hyperoxic compared with in normoxic rabbits and lidocaine treatment attenuated the increase (opsonized zymosan stiluated: 3.7×106cpmvs2.3×106cpm,P<0.05). Exposure to 100% oxygen caused extensive morphologic lung damage which was lessened by lidocaine (lung injury score (mean): 3vs4,P<0.05).

Conclusion:These findings suggest that intravenous lidocaine has a prophylatic effect on initial hyperoxic lung injury (pulmonary vascular permeability, histopathological, and biochemical BALF changes) in rabbits. The effects of lidocaine on more severe lung injury (decreased oxygenation) caused by hyperoxia for 72 h deserve further study.
Patient‐controlled premedication by iv midazolam for ambulatory surgery
Authors: Bernard J‐M. , Faintreny A. , Lienhart A. , Souron R.
Published: January 2009

Applying the principle and equipment of patient‐controlled analgesia, this double‐blind randomised study was designed to determine the premedication dose of midazolam and to provide information about the need for preoperative anxiety control.

The effects of patient‐controlled premedication by iv midazolam were compared to those of a 1‐hour iv infusion of a fixed dose of 4 mg. Two groups of 25 patients were studied prior to ambulatory surgery. Using a visual analogue scale graded from 0 (no anxiety) to 100, anxiety and short‐term memory as well as vital signs, vigilance, cognition and orientation were assessed before premedication and then every 20 min until admission to the operating room.

In both groups, 40% of the patients were free of anxiety before prernedication. Sixty‐four percent of patients in the self‐premedicated group never used the pump. The dose of midazolam was only 0.7 0.2 mg (mean SD) in this group taken as a whole, 0.7 1.1 mg (mean SD) in the 8 patients who had an anxiety score at least equal to 50 before premedication, and 1.7 0.3 mg (mean SD) in the 9 patients who chose to push the button of the patient‐controlled device. Anxiety and short‐term memory scores decreased significantly and similarly in the self‐prernedicated group and in the fixed‐dose group. For similar intraoperative anaesthetic requirements, time from the end of anaesthesia for determining whether a patient was ready for admission to the postrecovery lounge was shorter in the self‐premedicated group (26±8 min vs 32±8 min; mean±SD. Reduced doses of midazolam self‐administered via a patient‐controlled device can result in a relaxed preoperative period and amnesia in ambulatory surgery patients. However, the level of anxiety before prernedication was low, which calls into question the legitimacy of the patient‐controlled premedication in this kind of population. The expense of the pump was not justified by the small number of patients using it, probably because they were worried by the technical nature and the invasiveness of this technique.
In vitromyocardial depression by ketamine or thiopental is dependent on the underlying beta‐adrenergic tone
Authors: Thurston T. A. , Mathew B. P.
Published: January 2009

Background:Depression of myocardial contractility by muscarinic stimulation is dependent on the underlying beta‐adrenergic tone. Prior beta‐adrenergic stimulation enhances muscarinic negative inotropic responses, an effect that has been termed accentuated antagonism. The purpose of this study was to determine whether accentuated antagonism occurs with myocardial depression caused by thiopental or ketamine.

Methods:Using an isolated, electrically stimulated rat left atrium model, the dose‐response curves to the muscarinic agonist carbachol and the anesthetics ketamine and thiopental were compared under conditions of high (10‐6M isoproterenol bath concentration) or low (10‐6M propranolol) beta‐adrenergic tone.

Results:As expected, depression by carbachol was accentuated in preparations stimulated with isoproterenol compared with atria treated with propranolol. The decrease in tension by high doses (>400 μM thiopental, >200 μM ketamine) of thiopental or ketamine was attenuated in isoproterenol‐stimulated tissue when compared with beta‐adrenergic blocked muscle. Low concentrations (200 μM thiopental, 100 μM ketamine) of anesthetic caused either no change in contractility (thiopental) or small positive inotropic responses (ketamine) in propranolol‐treated but not isoproterenol‐stimulated tissue.

Conclusions: In contrast to muscarinic agonists, myocardial depression by high concentrations of ketamine or thiopental is attenuated by prior beta‐adrenergic stimulation. Positive inotropic responses may be seen with low concentrations of ketamine in muscle with low beta‐adrenergic tone. The results of this study demonstrate that the underlying beta‐adrenergic tone greatly influences thein vitroresponse of cardiac tissue to ketamine or thiopental.
The effect of continuous epidural infusion of ropivacaine (0.1%, 0.2% and 0.3%) on nerve conduction velocity and postural control in volunteers
Authors: Zaric D. , Nydahl P.‐A. , ÄDel S.‐O. , Enbom H. , Magnusson M. , Philipson L. , Axelsson K.
Published: January 2009

Background: Continuous epidural infusions of local anaesthetics have become increasingly popular in postoperative pain treatment, especially as they permit early mobilisation. Ropivacaine is a promising new agent which induces more pronounced sensory than motor blockade. This study was focused on the influence of continuous epidural infusion of ropivacaine on impulse conduction in large nerves (by measurement of F and H latencies), and on the subjects' ability to maintain postural control during mobilisation.

Methods: Healthy male volunteers received 0.1%, 0.2% or 0.3% ropivacaine, and bupivacaine 0.25% was used as reference. A bolus epidural injection of 10 ml of the drug, at L2/3 level, was followed by continuous infusion at 10 ml/h for 21 h. Motor blockade was assessed by mechanical measurements of force during big toe flexion and by recording of F latency. Sensory blockade was monitored by pin‐prick and Thermotest methods, and by H latency recording. The subjects' ability to perform a postural test was evaluated by posturography.

Results: The F and H latencies became prolonged/abolished dose‐dependently. With ropivacaine, F latency recovered significantly later than motor function (P = 0.0002), and H latency recovered later than normal pin‐prick perception (P = 0.0006). However, the duration of partial blockade of thermopercep‐tion was comparable to that of H latency prolongation. Posturographically, the subjects receiving 0.1% ropivacaine differed significantly from all others (P<0.001) in that they were able to maintain postural control during the infusion. The recovery period after termination of infusion was significantly shorter with ropivacaine than with bupivacaine for all measured variables.

Conclusion: Recovery of postural control with 0.2% and 0.3% ropivacaine is significantly faster than with bupivacaine 0.25%. H latency recording allows detection of epidural blockade intensity that does not prevent subjects from performing postural tests.