bluuebunny/crossref_metadata_2025 huggingface dataset:
Hemodynamic and catecholamine response to isoflurane versus droperidol in complement to fentanyl anaesthesia
Authors: Tandonnet F. , Bourgain J. L. , McGee K. , Comoy E. , Truffa‐Bachi J.
Published: January 2009

Droperidol (0.03 mg X kg‐1to 0.25 mg X kg‐1) with fentanyl has been reported to be less efficient than volatile agents in the prevention of haemodynamic responses to surgery. The aim of this study was to investigate the use of high‐dose droperidol in complement to fentanyl in comparison with isoflurane and fentanyl anaesthesia. Thirty patients undergoing laryngectomy were studied. Systolic blood pressure (SBP), heart rate (HR) and plasma catecholamines were analysed both during anaesthesia and during recovery. During surgery, SBP epinephrine (E) levels did not change in either group. HR was slightly lower during droperidol fentanyl anaesthesia. Norepinephrine (NE) levels were significantly higher in the droperidol group than in the isoflurane group (P<0.05). During recovery, in both groups, SBP increased by 20% whereas E levels increased by 65%. NE levels increased post‐operatively in both groups, but this rise was significantly higher in the droperidol group (P<0.01). It is concluded that the two techniques contribute to the haemodynamic stability during surgery, but do not prevent haemodynamic instability during recovery.
Comparison of ephedrine and etilefrine for the treatment of arterial hypotension during spinal anaesthesia in elderly patients
Authors: Taivainen T.
Published: January 2009

Thirty ASA II‐III patients (>65 years) undergoing hip surgery under bupivaeaine spinal anaesthesia, and presenting a 25% reduction in mean arterial pressure (MAP), were included in the study. The patients were randomly allocated to receive, under double‐blind conditions, either ephedrine 0.07 mg kg‐1 or etilefrine 0.03 mg kg‐1 boluses i.v. when MAP decreased by 25% from the preanaesthetic reference value. There were no significant differences (mean ± s.d.) in the time interval between the sympathomimetics administered (ephedrine 20.2 ± 17.1 min, etilefrine 16.6 ± 7.0 min) or the number of sympathomimetics needed (ephedrine 3.8 ± 1.9, etilefrine 3.6 ± 2.2). In regard to MAP and diastolic arterial pressure (DAP), ephedrine was slightly more potent in restoring arterial blood pressure compared with etilefrine. The increases in systolic arterial pressure (SAP) and heart rate were similar in both groups. The administration of repeated doses of either sympathomimetic showed the same tendency to increase SAP, DAP, and MAP values as the first dose.
Breath‐by‐breath measurement of oxygen consumption and Fio2‐Feo2with increased oxygen demand
Authors: Davies R. E. , Noe F. E. , Whitty A. J. , Busby M. G. , Davies K. R.
Published: January 2009

Continuous on‐line breath‐by‐breath measurement of pulmonary gas exchange was used to monitor the increase in oxygen uptake (Vo2) and carbon dioxide excretion (Vco2) induced by the oxidative phosphorylation uncoupling agent 2, 4‐dinitrophenol (DNP) in 10 dogs. With incremental doses of DNP totaling 5 mg/kg, the continuously monitored Vo2 increased within 2–3 min after the first injection of the drug. Vco2 showed a similar response 4–6 min after the first injection. Temperature increase due to the pharmacological oxidative phosphorylation uncoupling required 20–30 min for a discernible change at this dose. This study also demonstrated a modified and compromised response to the drug in dogs where oxygen delivery was limited by mechanical ventilation.
Halothane enhances the binding of diazepam to synaptic membranes from rat cerebral cortex
Authors: Nakao S. , Arai T. , Murakawa M. , Mori K.
Published: January 2009

The effects of halothane on diazepam binding to the rat cerebral synaptic membranes were investigated. Halothane at the concentrations of 0.63, 1.3 and 4.1 mmol/1 increased the binding by 12, 23 and 33%, respectively, compared to the control in the absence of halothane. The increments were dependent on the presence of Cl. The findings indicate that halothane and diazepam have an interaction at receptor level.
Assessing the adequacy of fentanyl anesthesia: plasma concentrations and lower esophageal contractility
Authors: Schwieger I. M. , Hall R. I. , Hug C. C.
Published: January 2009

Assessing the adequacy of anesthesia in the paralyzed patient is usually based on sympathetic and hemodynamic responses to noxious stimulation. Absence of such responses does not guarantee adequate anesthesia. A device monitoring the amplitude of provoked lower esophageal, contractility (PLEC) and the rate of spontaneous lower esophageal contractility (SLEC) has been developed as a potential monitor of the adequacy of anesthesia. This study determined the reliability of this device for monitoring anesthetic depth in 20 patients receiving fentanyl infusions who were undergoing coronary artery surgery and who were hemodynamically stable in the preoperative period. Premedication included midazolam 0.05 mg/kg i.m. and ranitidine 2 mg/kg p.o. Anesthesia was induced with fentanyl 50 μg/kg administered over 10 min and maintained by a fentanyl infusion 0.2 μgkg‐1min‐1. Following endotracheal intubation, a disposable esophageal monitoring probe, equipped with provoking and measuring balloons, was inserted and both the amplitude of provoked (PLEC) and the rate of spontaneous lower esophageal contractions (SLEC) were displayed and recorded. Precisely defined clinical signs of inadequate anesthesia included both somatic and hemodynamic responses to noxious stimulations. The presence of these responses was correlated with PLEC and SLEC and with fentanyl concentrations in plasma at specific times of noxious stimulation during the period preceding initiation of cardiopulmonary bypass. A total of 208 episodes of noxious stimulation were recorded at insertion of the nasal temperature probe (n = 8), at penetration of the skin by towel clips (n = 25), at skin incision (n = 20), at sternotomy (n = 20) and during multiple episodes of electrocauterization (n = 135). These provoked 52 clinical responses. The rate of the spontaneous contractions at times of response (4.5 4.6 contractions per 3 min, mean s.d.) was significantly greater than that at times of no response (2.5 2.7 contractions per 3 min; P<0.01), whereas there was no significant difference in the amplitude of provoked contractions (17 7 mmHg vs 15 4 mmHg (2.3 0.9 vs 2.0 0.5 kPa); P>0.05). The most favorable cut‐off point was determined to be a rate of 3 contractions per 3‐min period. This produced a false positive rate of 41.7% and a sensitivity (true positive rate) of 59.6%. There was no clear relationship between plasma concentrations of fentanyl and the rate of spontaneous contractions, or hemodynamic or somatic response to stimulation. We conclude that monitoring lower esophageal contractility is not reliable for detection of inadequate opioid anesthesia.
Comparison of standard and high‐dose adrenaline in the resuscitation of asystole and electromechanical dissociation
Authors: Lindner K. H. , Ahnefeld F. W. , Prengel A. W.
Published: January 2009

Sixty‐eight adults with cardiac arrest (asystole and electromechanical dissociation) were randomly allocated for treatment with standard (1 mg) or high‐dose epinephrine (5 mg). If the first dose of adrenaline 11 or 5 mg) failed, standardized advanced life‐support was applied in all cases. High‐dose adrenaline was associated with higher initial resuscitation success rates (16 of 28) than standard‐dose adrenaline (6 of 40), whereas hospital discharge rates were not significantly different between the groups. Blood pressure was significantly higher in the high‐dose adrenaline group in comparison to the standard dose at 1 and 5 min after resuscitation. Although high‐dose adrenaline appears to improve cardiac resuscitation success, the duration of global cerebral ischaemia seems to determine the ultimate outcome.
Tissue extravasation of albumin from intraabdominal trauma in rats
Authors: Akerström G. , Lisander B.
Published: January 2009

Intraabdominal surgery tends to lower circulating plasma volume by mechanisms unrelated to bleeding and evaporation. In chloralose‐anesthetized rats, the tissue clearance of radiolabelled albumin was determined by a double isotope method. Animals were subjected to a standardized abdominal trauma, eliciting minimal bleeding and evaporation, and others served as controls. The trauma significantly increased tissue albumin extravasation in abdominal skin, abdominal wall, pancreas, small intestine, colon, mesentery and diaphragm. Considering the mass of the respective tissues, a substantial portion of the albumin extravasation took place in the abdominal wall. No increased albumin clearance was found in extraabdominal tissues. It is suggested that abdominal surgery decreases plasma volume by extravasation in the operation field.
A comparison of intravenous ketoprofen with pethidine for postoperative pain relief following nasal surgery
Authors: Elhakim M.
Published: January 2009

A controlled investigation was conducted to compare the efficacy of ketoprofen and pethidine in relief of postoperative pain after nasal surgery. Sixty patients were randomly allocated to receive intravenous ketoprofen 1.5 mg · ml‐1 or pethidine 1 mg · kg‐1 during induction of anaesthesia. Appearance, pain and headache were assessed 1, 2, and 4 h postoperatively, and the following morning. The use of ketoprofen was associated with a significantly faster recovery from anaesthesia (P<0.001), and a more rapid return to calm awakening (P<0.05). Patients who received ketoprofen had significantly lower pain and headache scores (P<0.01 and P<0.001, respectively), and required significantly (P<0.05) less postoperative analgesia. No significant difference in incidence and severity of postoperative nausea or vomiting was found between the two groups at any time. A single intravenous dose of ketoprofen during anaesthesia may offer an advantage compared to pethidine in reducing postoperative pain following nasal surgery.
Intramuscular dexmedetomidine, a novel alpha2‐ adrenoceptor agonist, as premedication for minor gynaecological surgery
Authors: Aantaa R. , Kanto J. , Scheinin M.
Published: January 2009

The effects of three different doses (0.5, 1.0 and 1.5 μg/kg) of dexmedetomidine, a novel α2‐adrenoceptor agonist, on vigilance, anaesthetic requirements, haemodynamics, and plasma catecholamine levels were investigated in a double‐blind placebo‐controlled study in 20 healthy (ASA physical status I‐II) women scheduled for uterine dilatation and curettage (UD & C). The drug was administered intramuscularly 60 min before induction of anaesthesia with thiopentone. N2O/O2(70/30%) and thiopentone was used for maintenance. There were no significant differences between the groups in thiopentone requirements, plasma adrenaline concentrations, or subjective or objective assessment of sedation before anaesthesia and UD & C. Blood pressure, heart rate, and plasma noradrenaline levels were reduced after dexmedetomidine, with three patients receiving atropine for excessive bradycardia (less than 45 beats min‐1). The haemodynamic as well as the sedative effects of dexmedetomidine after surgery lasted until the end of the observation period, 4 h after the injection of the drug, indicating that intramuscular administration of this premedication agent may result in a longer than optimal duration of pharmacological actions in connection with short surgical procedures.
Rebreathing during oxygen treatment with face mask
Authors: Jensen A. G. , Johnson A. , Sandstedt S.
Published: January 2009

The influence of different oxygen flow rates on ventilation and arterial blood gases was investigated in ten healthy volunteers during oxygen treatment with the Hudson® mask. Respiratory parameters were calculated using inductive plethysmography calibrated against pneumotachography. The minute ventilation was greater when using the mask with oxygen flow rates less than 5 1/min compared to when no mask was used. With an oxygen flow rate of 3 1/min, minute ventilation was about 140% of minute ventilation without face mask. With 0 1/min, minute ventilation increased to about 160%. The increase in minute ventilation was mainly due to an increase in tidal volume. No change was seen, however, in Paco2 with different oxygen flow rates. Secondary objective signs following an increase in respiratory work (changes in heart rate, systolic blood pressure and oxygen saturation) were not seen. We recommend 5 1/min as the lowest oxygen flow rate to be used during oxygen therapy with the Hudson mask, in order to avoid rebreathing and excessive respiratory work.
Mucociliary transport with and without the use of a heat and moisture exchanger. An animal study
Authors: Eckerbom B. , Lindholm C.‐E. , Mannting F.
Published: January 2009

The importance to mucociliary transport (MCT) and the condition of the mucus of using a heat and moisture exchanger (HME) was investigated. A high tracheotomy was performed on 10 young pigs. The animals were ventilated using a non‐breathing system. In five animals an HME was used; the other five were connected directly to the ventilator circuit. After 6 h the trachea was inspected via a flexible bronchoscope. Mucociliary transport velocity was measured using Tc‐99‐marked macrospheres and a gamma camera. In the control group the tracheal mucus membrane was desiccated at half the distance from the tube tip to the bifurcation. In the HME group the entire trachea was well moistened, but two cases showed large amounts of abnormally thin and foamy secretion. Mucus quality differed significantly between the two groups. Maximum MCT velocities were 8.3 ± 4.6 and 4.9 ± 3.0 mm/min for the HME‐ and the control groups, respectively. The marker had moved 49 ± 32 and 35 ± 21 mm during 24 min. Neither of these differences was statistically significant. In the control group there was no transport over desiccated areas. We conclude: 1) the quality of tracheal secretion differed significantly between the two groups, and 2) a heat and moisture exchanger may retain too much water in the airway.
Penetration forces in cannulation of the dorsal veins of the hand: I. A comparison between polyurethane (Insyte®) and polytetrafluoroethylene (Venflon®) cannulae
Authors: Eriksson E. , Larsson N. , Nitescu P. , Appelgren L. , Linder L. E. , Curelaru I.
Published: January 2009

The functional tip tapering design of peripheral venous cannulae (introducer steel needle + catheter) made of polyurethane (PUR‐Insyte®) and polytetrafluoroethylene (PTFE‐Venflon®) was studied with 3 techniques: A) Scanning electron microscopy (SEM). B) Measurement of penetration forces in vitro through latex membranes and lamb skins with a tensile‐compression apparatus (Instron‐1122®) at 1) the introducer steel‐needle point, 2) the needle heel (the spot marking the passage from the point of the needle to its shaft), 3) the catheter top (i.e. the beginning of the plastic sheath), 4) the catheter tip, i.e. the beginning of the largest diameter of the plastic sheath, and 5) between the catheter tip and its hub (catheter friction). C) Two cannulae (one of each type for every subject) were inserted at random into the dorsal veins of the left and right hand in 37 volunteers, and the penetration forces were measured with a force transducer. Results: A) The PUR‐cannulae had a lancet‐like appearance and a smoother transition at the catheter top, whilst the PTFE cannulae were arrow‐like, cut back and had a less accentuated conical design. B) Penetration forces in vitro through latex membranes were 9–41 times lower (P<0.0001) than those through the lamb skins. The highest forces (mean · s.d.) registered in vitro (lamb skins) were 4.1 ± 0.2 Newtons (N) with PUR‐cannulae at the catheter tip, and 3.4 ± 0.6 with the PTFE‐cannulae at the catheter top (P<0.05). C). In in vivo (volunteers), significantly (P<0.001) higher forces were required with the PUR‐cannulae than with the PTFE‐cannulae for penetration of both the skin (3.9 ± 1.6 vs 2.7 ± 0.8 N) and the vein wall with continued penetration of the skin (3.5 ± 1.2 vs 2.4 ± 0.9 N). When the highest penetration forces were compared, no significant differences between in vitro (lamb skins) and in vivo (skin and vein with continued skin penetration) studies were found with either of the two cannulae studied. We conclude that there were statistically significant differences between penetration forces of the PUR and PTFE‐cannulae when inserted into the dorsal veins of the hand. Penetration forces in vitro (lamb skins) may predict with acceptable accuracy the penetration forces in vivo (dorsal veins of the hand).
Effects of caffeine, halothane, succinylcholine, phenylephrine and isoproterenol on myocardial force of contraction of malignant hyperthermia susceptible swine
Authors: Scholz J. , Roewer N. , Rum U. , Schmitz W. , Scholz H. , am Esch J. Schulte
Published: January 2009

The effects of caffeine, halothane, succinylcholine, phenylephrine and isoproterenol on force of contraction were studied in electrically driven (0.2 Hz) trabeculae isolated from the right ventricles of the hearts of malignant hyperthermia susceptible (MHS) and healthy control (nMHS) swine. Caffeine (0.1–10 mmol/l) had positive inotropic effects, amounting to 275 ± 35% of control in nMHS and 268 ± 34% in MHS (n = 16). Halothane (0.25–4 vol%) decreased the force of contraction maximally to 52 ± 4% in nMHS and 51 ± 5% of control in MHS (n = 16). Propranolol did not change these effects. Succinylcholine (0.1–1000 μmol/l) had a small positive inotropic effect in both groups, which was blocked by propranolol. Phenylephrine (0.1–300 μmol/l) increased the force of contraction maximally to 188 ± 24% of control in nMHS and to 193 ± 23% in MHS (n = 16). The inotropic effect was blocked by prazosin but not by succinylcholine (1 mmol/l). Isoproterenol (0.01–10 μmol/l) had a positive inotropic effect of maximally 275 ± 21% of control in nMHS and 396 ± 31% in MHS (n = 17) (P<0.05). Succinylcholine potentiated this effect, and propranolol shifted the concentration‐response curves to the right. We conclude that caffeine, halothane, succinylcholine and phenylephrine have similar inotropic effects in the hearts of nMHS and MHS, whereas isoproterenol has a significantly greater effect in MHS than in nMHS.
Tracheal intubation after induction of anaesthesia with thiopentone or propofol without muscle relaxants
Authors: Hovorka J. , Honkavaara P. , Korttila K.
Published: January 2009

This study was designed to compare the ease of performing laryngoscopy and endotracheal intubation without muscle relaxants after the induction of anaesthesia with either thiopentone or propofol in 106 patients scheduled for elective surgery. Thiopentone (5 mg/kg) or propofol (2.5 mg/kg), supplemented with lidocaine (1.5 mg/kg) and alfentanil (30 μg/kg), were used in random order for the induction of anaesthesia. Jaw tone, visualisation of the larynx, position of vocal cords, ease of intubation and tolerance of the tracheal tube were assessed. The jaw was relaxed and the vocal cords were immobile/open in most patients in both groups. Visualisation of the larynx was good in 60 and 46%, and intubation was easy in 48 and 22% of the patients given thiopentone and propofol, respectively (P<0.05 between groups for intubation). After induction of anaesthesia with thiopentone or propofol, endotracheal intubation is not recommended without the use of muscle relaxants.
Left ventricular diastolic function during short‐term positive end‐expiratory pressure ventilation in dogs
Authors: Hevrøy O. , Kløw N. E.
Published: January 2009

Simultaneous recordings of left ventricular (LV) pressure and volume (sonomicrometry) were made in acutely instrumented dogs anaesthetized with pentobarbital during intermittent positive pressure ventilation with zero and positive end‐expiratory pressure at 10 and 20 cmH2O (PEEP10 and PEEP10). Pericardial pressure was measured continuously in order to obtain transmural LV pressure. PEEP reduced LV end‐diastolic volume and transmural pressure significantly. This was accompanied by significantly reduced stroke volume. LV peak diastolic filling rate, calculated as dV/dtmax, was significantly reduced when PEEP was applied, independent of LV volume alterations. LV diastolic compliance, assessed by the slope of LV pressure‐volume relationship during LV filling, decreased significantly with increasing PEEP levels. A positive correlation was observed between reductions in peak diastolic filling rate and reductions in end‐diastolic volume. The reduced peak diastolic filling rate, on the other hand, was closely correlated to reduced LV diastolic compliance. Isovolumetric relaxation rate (T) increased slightly at the highest PEEP level. This could, however, not be related to a reduced LV diastolic filling rate. The close association between reduced LV diastolic compliance and reduced diastolic filling rate may indicate that a tamponade‐like effect is involved in the reduction of LV preload observed during PEEP ventilation.
The role of nitrous oxide in postoperative nausea and recovery in patients undergoing upper abdominal surgery
Authors: Ranta P. , Nuutinen L. , Laitinen J.
Published: January 2009

The effect of nitrous oxide on postoperative nausea/vomiting and alertness were studied in 50 patients undergoing elective upper abdominal surgery. The study period lasted 20 h. Patients were randomly assigned to receive thiopentone‐fentanyl‐isoflurane‐pancuronium anaesthesia with either 70% nitrous oxide‐oxygen (Group I) or air‐oxygen (Group II). There were no differences between the groups regarding age, sex, weight or amount or per‐ and postoperative analgetics given. The mean inspiratory isoflurane concentrations were 0.6% and 1.15% in Groups I and II, respectively. The postoperative alertness was tested by a visual analogue scale (0–10) for 6 h postoperatively. Omitting nitrous oxide did not decrease the frequency of postoperative nausea, although the symptoms were milder in the air group. The patients without nitrous oxide were alert earlier, in spite of a higher isoflurane concentration: VAS from 5 to 8.7 vs from 2.8 to 6.9 during the first 6 postoperative hours.
Influence of adenosine and prostacyclin on hypoxia‐induced pulmonary hypertension in the anaesthetized pig
Authors: Öwall A. , Davilén J. , Sollevi A.
Published: January 2009

The effects of adenosine and prostacyclin (PGI2) infusions on hypoxia‐induced pulmonary hypertension in the pulmonary and systemic circulatory systems of nine pigs were compared. The animals received the drugs in random order, and they were allowed to recover between each experimental sequence. Hypoxia was induced by reducing Fio2 to 0.12–0.13 so as to result in an arterial Po2 of approximately 6 kPa. Dose rates of adenosine or PGI2 during hypoxia were individualized in order to achieve a maximal reduction of 15% in the mean arterial blood pressure. Adenosine and PGI2 produced a fall in pulmonary vascular resistance of 36 ± 4% (s.e.mean P<0.01) and 37 ± 6% (P<0.01), respectively. The mean pulmonary artery pressure was reduced by 19 ± 3% (P<0.01) during adenosine infusion and by 36 ± 4% (P<0.01) during PGI2 infusion. The systemic haemodynamic responses to the two drugs were similar but adenosine produced a 7 ± 2% (P<0.01) increase in cardiac output. Arterial Po2 during hypoxia and vasodilator treatment did not differ from the hypoxic situation without drug infusion. It is concluded that adenosine and PGI2 counteract hypoxia‐induced increases in pulmonary vascular resistance similarly, but the reduction in pulmonary artery pressure was greater with PGI2 at infusion rates, causing minor systemic haemodynamic changes.
Effects of thoracic epidural anesthesia and adrenoceptor blockade on the cardiovascular response to dopamine in the dog
Authors: Lundberg J. , Biber B. , Henriksson B.‐A. , Martner J. , Raner C. , Werner O. , Winsö O.
Published: January 2009

The cardiovascular effects of dopamine are different before and during thoracic epidural anesthesia (TEA). To evaluate underlying adrenoceptor‐mediated mechanisms, dopamine effects were investigated in nine chloralose‐anesthetized dogs. The circulatory response to dopamine (0–40 μg · kg‐1· min‐1) was studied before and during TEA, and during TEA after introducing the α1‐antagonist prazosin (0.3 mg · kg‐1), the α2‐antagonist rauwolscine (0.3 mg · kg‐1), and the β1‐antagonist metoprolol (0.5 mg · kg‐1). TEA decreased mean arterial pressure (MAP) by 29%, cardiac output (CO) by 36%, heart rate (HR) by 27%, and the maximum rate of change of left ventricular pressure (LVdP/dt) by 52%. Systemic vascular resistance, pulmonary vascular resistance and mean pulmonary artery pressure (MPAP) remained unaltered by TEA. Dopamine‐induced increases in MAP and HR were augmented by TEA. Both MAP and LVdP/dt increased above pre‐TEA levels at 10 μg · kg‐1· min‐1. Prazosin attenuated the increases in MAP and MPAP by dopamine. Adding rauwolscine almost abolished the dopamine response in MAP and MPAP. Metoprolol almost eliminated the dopamine effects on CO and LVdP/dt. Only minor alterations in cardiac filling pressures were observed during the study. Plasma norepinephrine (NE) concentration was lower during than before TEA at corresponding dopamine infusion rates. NE was reduced by the β1‐blockade. During TEA, the plasma dopamine levels were generally higher, and they were further increased by adding β1‐blockade. In conclusion, myocardial contractility and arterial pressure were restored to pre‐TEA values by dopamine at 5–10 μg · kg‐1· min‐1. The circulatory response to dopamine during TEA is mainly mediated by α1‐, α2‐ and β1‐adrenoceptor activation, and may be influenced by altered plasma catecholamine levels.
Postoperative episodic oxygen desaturation in the sleep apnoea syndrome
Authors: Rosenberg J. , Kehlet H.
Published: January 2009

We describe a patient with sleep apnoea syndrome who showed severe episodic hypoxaemia in the late postoperative period. The sleep apnoea syndrome should be studied further to evaluate its significance as a surgical risk factor.
Hypoalgesia following intrathecal morphine: a segmental dependent effect
Authors: Arendt‐Nielsen L. , Anker‐Møller E. , Bjerring P. , Spangsberg N.
Published: January 2009

The onset phase of hypoalgesia, following intrathecal morphine, was assessed by experimental argon laser‐induced pain. A dose of 0.4 mg morphine was injected pre‐operatively at the L3‐L4 level into nine patients. The thresholds to laser‐induced pain and pain‐evoked brain potentials were monitored for 2 h at the Sl, LI, and C7 dermatomes. Hypoalgesia was detected at the SI and LI dermatomes after 5 and 15 min, respectively. No hypoalgesic effect was found at C7. This indicates that hypoalgesia was caused predominantly by segmental spinal mechanisms during the onset phase, and not by a general widespread effect. No latency changes (conduction delay) of the brain potentials evoked from the hypoalgesic dermatomes were found. Cutaneous pain, induced experimentally by laser stimulation, has the advantage of being quantitative and is useful to assess the onset and the segmental spread of hypoalgesia.
Hypoalgesia following epidural morphine: a controlled quantitative experimental study
Authors: Arendt‐Nielsen L. , ØOSberg B. , Bjerring P.
Published: January 2009

The efficacy, duration, and spread of epidural morphine hypoalgesia were assessed by an experimentally induced pricking pain evoked by laser stimulation. Four mg of plain morphine was injected epidurally in 7 volunteers at the L2‐L3 interspace. Thresholds to warmth and pain perception, and pain‐evoked potentials were measured. In the first experiment, hypoalgesia was monitored each hour for 7 h at various dermatomes. Hypoalgesia was detected at SI dermatome after 2 h, but 3 h elapsed before hypoalgesia could be detected at the LI, T12, T10, T8, and T6 dermatomes. No effect was found at C7. No conduction delay was found along the pain pathway during hypoalgesia. Hypoalgesia lasted more than 7 h at S1, whereas hypoalgesia could not be detected after 5 h at other dermatomes. In the second experiment, naloxone (0.8 mg i.v.) was injected 230 min after injection of epidural morphine, and the subsequent recording 10 min later showed that hypoalgesia had been partly reversed. The onset and duration of hypoalgesia are different for experimentally induced pain and clinical pain. Experimentally laser‐induced pain has the advantage of being quantitative, and is, as such, useful to assess hypoalgesia, and to test the potency of narcotics.
Hemodynamic and catecholamine responses to laryngoscopy with vs. without endotracheal intubation
Authors: Hassan H. G. , El‐Sharkawy T. Y. , Renck H. , Mansour G. , Fouda A.
Published: January 2009

To study the relationship between the intensity of the stimulus exerted against the base of the tongue during direct laryngoscopy and the magnitude of associated hemodynamic and catecholamine responses, a study was conducted in 40 ASA 1 or 11 patients. Laryngoscopy lasting 40 s was performed with a size 3 Macintosh blade connected to a force‐displacement transducer. The intensity of the stimulus exerted during laryngoscopy is expressed by the product of its average force (N) and duration (s) and given as impulse in Ns. Highly significant relationships were found between the impulse during laryngoscopy and the maximal hemodynamic and catecholamine responses. Also, when laryngoscopy was followed by orotracheal intubation, significant relationships were found with steeper slopes of the regression lines for systolic blood pressure, heart rate and plasma epinephrine concentrations. A more rapid regression of hemodynamic data was seen in intubated patients, whereas their plasma catecholamine concentrations regressed more slowly. The mechanisms of the responses to laryngoscopy and orotracheal intubation are proposed to be by somato‐visceral reflexes. Stimulation of proprioceptors at the base of the tongue during laryngoscopy induces impulse‐dependent increases of systemic blood pressure, heart rate and plasma catecholamine concentrations. Subsequent orotracheal intubation recruits additional receptors that elicit augmented hemodynamic and epinephrine responses as well as some vagal inhibition of the heart.
The effect of positive end‐expiratory pressure ventilation on atrial filling
Authors: Riddervold F. , Smiseth O. A. , RisØoSe C.
Published: January 2009

As a measure of atrial filling, left and right auricular diameter and free wall segment length were recorded by sonomicrometry during incremental positive end‐expiratory pressure (PEEP) in eight acutely instrumented closed chest dogs. The effect of PEEP was assessed with the pericardium open (n = 6) and closed (n = 8). On both occasions, PEEP decreased left auricular diameter (P<0.05). PEEP also caused a reduction in right auricular diameter with the pericardium open (P<0.05), while the variable was unchanged with the pericardium closed. PEEP did not cause any changes in either left or right free wall segment lengths. Both left and right auricular pressure‐diameter relationships were progressively shifted leftwards with incremental PEEP. These observations suggest that PEEP may reduce left ventricular output not only by interfering with passive ventricular filling, but also by reducing atrial dimensions.
Effects of famotidine on gastric pH and residual volume in pediatric surgery
Authors: Jahr J. S. , Burckar G. , Smith S. S. , Shapiro J. , Cook D. R.
Published: January 2009

Aspiration pneumonitis is a severe complication of anesthesia. The objectives of this study were to determine if preoperative famotidine, a new histamine2‐receptor antagonist, given by mouth either the evening before or the morning of elective surgery, reduced gastric residual volume and increased gastric pH in pediatric patients. Either famotidine or placebo (or both) were orally administered to 58 children (aged 2–17 years). The patients were randomly assigned to four groups: Famotidine‐Famotidine, Placebo‐Placebo, Placebo‐Famotidine, and Famotidine‐Placebo; subjects in the Famotidine‐Famotidine group received two doses of famotidine (0.5 mg‐kg‐1 per dose), those in the Placebo‐Placebo group, two doses of placebo, those in the Placebo‐Famotidine and Famotidine‐Placebo group, one dose of each by mouth. The Famotidine‐Famotidine group received one dose of famotidine at 22:00 the evening before surgery and a second dose 60–90 min before the scheduled time of surgery. The Placebo‐Placebo group received two doses of placebo at the same times as the Famotidine‐Famotidine group. The Placebo‐Famotidine group received a dose of placebo the night before surgery and a dose of famotidine the morning of surgery; the Famotidine‐Placebo group received famotidine the night before surgery and placebo the morning of surgery. The administration of famotidine on the morning of surgery significantly increased gastric pH (4.8 vs. 1.3) in comparison with placebo, as did two doses of famotidine (6.6). Famotidine failed to reduce gastric residual volume significantly in any group. The administration of famotidine significantly reduced the number of pediatric patients considered at higher risk for aspiration pneumonitis, despite not decreasing gastric residual volume.
Postischaemic regional microvascular variations in the porcine renal cortex
Authors: Sandin R. , Feuk U. , Modig J.
Published: January 2009

Regional microcirculatory differences in the superficial renal cortex were studied before and during 4 h following 60 min of renal ischaemia in seven pigs under continuous intravenous chlormethiazole‐pancuronium anaesthesia. Superficial renal cortical blood flow (Qsrc) was measured by laser Doppler flowmetry (LDF) in two different regions. In two other different regions tissue oxygenation (Pto2) was measured by surface electrodes. Thus, microcirculatory measurements were simultaneously carried out in each animal in four different regions of the left kidney. After 60 min of renal ischaemia, pronounced renal cortical microcirculatory disturbances were found. The regional microcirculatory differences were notable, especially after ischaemia. On average, Qsrc was 49 ± 11 (s.d.) arbitrary units at baseline and decreased to 24 ± 4 arb. units 4 h after start of reperfusion (P<0.05). Before ischaemia the average difference between Qsrc simultaneously measured in two different parts of the renal cortex was 26 ± 15% of the mean of both measurements, and it was 30 ± 22% 4 h after start of reperfusion (n.s.). Mean Pto2 (m‐Pto2) was on average 4.5 ± 1.3 kPa at baseline and 2.4 ± 1.5 kPa 4 h after start of reperfusion (P<0.05). The average difference between m‐Pto2 simultaneously measured in two different parts of the renal cortex at baseline was 24 ± 13% of the mean of both measurements and 57 ± 49% 4 h after start of reperfusion (n.s.). In each of the two measured regions of the renal cortex m‐Pto2 was calculated from 160 small tissue volumes distributed within a surface area of about 1 mm2. The percentage of these 160 measurements which exhibited Pto2<0.6 kPa (L‐Pto2) was, on average, 1 ± 2% at baseline and increased to 19 ± 25% 4 h after start of reperfusion (P<0.05). The average difference in L‐Pto2 between the two measured regions was 1 ± 3% at baseline and 17 ± 21% 4 h after start of reperfusion (n.s.). The microcirculatory disturbances after ischaemia were strongly dependent on the elapsed time after start of reperfusion. Thus, measurements by techniques allowing continuous or repeated recordings are advantageous. Due to regional variability, Pto2 and LDF measurements from several animals or from multiple regions in the renal cortex must be considered in order adequately to describe the postischaemic renal cortical microcirculation.
Comparison of North American and European malignant hyperthermia group halothane contracture testing protocols in swine
Authors: Fletcher J. E. , Conti P. A. , Rosenberg H.
Published: January 2009

Different in vitro halothane testing procedures have been used in the European malignant hyperthermia (MH) Group Protocol (EMHGP) and the North American MH Group Protocol (NAMHGP), whereas the caffeine‐testing protocols are very similar. The present study compares the two halothane‐testing protocols in ten MH susceptible swine and in four control swine. Halothane contracture testing was conducted in vitro 12–52 days following the barnyard challenge that established the MH susceptibility of the swine. There was one false positive and one false negative halothane test by the EMHGP. The MH‐equivocal category in the EMHGP, which is treated clinically as MH‐susceptible, affords a margin of safety in such cases. In contrast, there were no false halothane tests by the NAMHGP. While some skeletal muscle strips from MH pigs were normal by both protocols (NAMHGP 30%; EMHGP 10%), the outcome of halothane testing by the NAMHGP was unaffected. The response to halothane 3% is reduced if preceded by the EMHGP, suggesting that simply adding halothane 3% to the end of the EMHGP does not permit a direct quantitative comparison to the NAMHGP. However, the diagnostic outcomes of the two approaches are similar.
Effects of bupivacaine and calcium antagonists on human uterine arteries in pregnant and non‐pregnant women
Authors: Norén H. , Lindblom B. , Källfelt B.
Published: January 2009

Bupivacaine is a local anesthetic commonly used in obstetrical practice. Although not generally constrictive, it has a constricting effect on blood vessels in clinically used doses, and when administered close to the uterine vasculature, as in a paracervical blockade, it can induce severe fetal bradycardia and thus be hazardous to the fetus. The bupivacaine‐induced vasoconstriction on uterine arteries from pregnant and non‐pregnant women was effectively reduced by two different calcium antagonists, verapamil and nifedipine. In non‐pregnant women, nifedipine (2.9 times 10‐2 mol·l‐1) administered simultaneously with bupivacaine (5.8 times 10‐1 mol·l‐1) caused a 96% and verapamil (10‐5 mol·l‐1) an 84% reduction as compared with the control vessel where only bupivacaine (5.8 times 10‐4 mol·l‐1) was administered. In pregnant women, nifedipine 2.9 times 10‐1 mol·I‐1 and 2.9 times 10‐6 mol·l‐1 produced 66% and 79% reductions, respectively. It is possible that calcium antagonists administered together with bupivacaine in paracervical blockade could reduce the risk of fetal bradycardia.
Effects of thoracic epidural anesthesia on myocardial pH and metabolism during ischemia
Authors: Tsuchida H. , Omote T. , Miyamoto M. , Namiki A. , Ichihara K. , Abiko Y.
Published: January 2009

The effect of thoracic epidural anesthesia (TEA) on the ischemic myocardium was examined in open‐chest dogs anesthetized intravenously. Ischemia induced by brief coronary artery occlusion caused an elevation of the ST segment in epicardial ECG and a reduction in myocardial pH and contractile force. TEA with 0.15 ml/kg of 0.4% bupivacaine solution attenuated an ischemia‐induced decrease in myocardial pH and an increase of the ST segment in epicardial ECG. This attenuation was maintained even after the restoration of blood pressure and heart rate, which had been decreased significantly after TEA, to pre‐TEA levels, suggesting that a beneficial effect of TEA should not be confined to its hemodynamic changes such as decreased blood pressure and heart rate. In contrast, the subendocardial contents of ATP, creatine phosphate (CP) and lactate were not affected by TEA, either in the presence or the absence of 5 min LAD occlusion. These results suggest that neither hemodynamic nor metabolic changes are responsible for the reduced myocardial ischemic acidosis induced by TEA after brief coronary artery occlusion. The acidosis‐saving property of TEA is favorable for the ischemic heart.
Continuous epidural infusion of bupivacaine and morphine for postoperative analgesia after hysterectomy
Authors: Asantila R. , Eklund P. , Rosenberg P. H.
Published: January 2009

The analgesic efficacy and side‐effects of combined epidural infusion of bupivacaine and morphine, in comparison with these drugs alone, for postoperative analgesia after hysterectomy (60 patients) were evaluated. Before general anaesthesia, all patients had an epidural catheter placed (Th11‐12) and 20 ml of 0.5% bupivacaine was injected. In random order, epidural infusion was continued for 24 h with either 0.25% bupivacaine 4 ml‐ h‐1 (BUPI‐group), a bolus of 2 mg of morphine followed by morphine 0.2 mg‐ h‐1 (MO‐group), or a combination of the two drugs (COMB‐group). A urinary bladder catheter was kept for 24 h. Supplementary postoperative pain medications were i.m. morphine 0.1 mg‐ kg‐1 or rectal indomethacin 50 mg, on request. Immediately after awakening from general anaesthesia and transfer to the recovery room, 18/20 of the BUPI‐group patients, 17/20 of the MO‐group patients and 19/20 of the COMB‐group patients were pain‐free. In the postoperative evening and the first postoperative morning, the corresponding figures were 7/20 and 10/20 in the BUPI‐group, 15/20 and 15/20 in the MO‐group, and 18/20 and 15/20 in the COMB‐group (postop. evening; P<0.01 BUPI vs. others). The number of patients requiring supplementary analgesics (morphine and indomethacin) during the first 24 h was greatest in the BUPI‐group (P<0.01). The number of patients who vomited during the 24‐h period was 3 in the BUPI‐group, 9 in the MO‐group and 5 in the COMB‐group. Postoperatively, normal bowel function was restored after 1.9 days in the BUPI‐group, 2.2 days in the MO‐group and 2.6 days in the COMB‐group, on average (P<0.01 BUPI vs. COMB). Recatheterization of the urinary bladder (once) was required in 4 patients in the MO‐group and 2 in the COMB‐group, but in none of the BUPI‐group. It is concluded that although the morphine‐containing epidural infusions (6.8 mg 24 h‐1) were superior to that containing bupivacaine alone with respect to postoperative analgesia after hysterectomy, the occurrence of disturbing emetic and urinary side‐effects made the therapy not totally satisfactory.
Clinical evaluation of electrostimulation anaesthesia for hysterectomy
Authors: Böhrer H. , Quintel M. , Fischer M. V.
Published: January 2009

A prospective randomized study was undertaken to evaluate the efficacy of electrostimulation anaesthesia (ESA) when compared with neurolept anaesthesia (NLA). One hundred patients scheduled for hysterectomy received either ESA or NLA. Higher levels of mean arterial pressure and heart rate in the ESA group make this technique less suitable for patients with a history of arterial hypertension. A higher dose of muscle relaxants was used in the ESA group. Measured stress variables like plasma glucose, cortisol, and iron indicate maintenance of the stress response during ESA. The postoperative questionnaire revealed intraoperative recall in 12% of ESA patients. We conclude that “pure” ESA based on a N2O regimen should be avoided.
Action of propofol on resistance and capacitance vessels during cardiopulmonary bypass
Authors: Baraka A. , Dabbous A. , Siddik S. , Bijjani A.
Published: January 2009

The peripheral vascular action of propofol on the resistance and the capacitance vessels was investigated in 16 patients during cardiopulmonary bypass. The venous reservoir (RV) and mean arterial pressure (MAP) were used as indices of the changes in venous capacitance and systemic vascular resistance (SVR), respectively. Propofol 2 mg · kg‐1 produced a decrease in MAP without a significant change in RV, suggesting that propofol preferentially decreases SVR without a significant change in venous capacitance.
Respiratory depression during epidural morphine treatment
Authors: Sjøgren P. , Jakobsen S. , Valentin N.
Published: January 2009

An 81‐year‐old woman was treated for 2 weeks with systemic opioids and for 2 days with epidural morphine before a severe and prolonged respiratory depression occurred.
The transurethral resection syndrome
Authors: Hahn R. G.
Published: January 2009

The transurethral resection syndrome (“TUR syndrome”) is caused by absorption of electrolyte‐free irrigating fluid, and consists of symptoms from the circulatory and nervous systems. The clinical picture is inconsistent and the syndrome is easily confused with other acute disorders. Mild forms are common and often go undiagnosed, while severe forms of the TUR syndrome are rare and potentially life‐threatening. The pathophysiology is complex but includes four mechanisms: circulatory distress from the rapid absorption of electrolyte‐free irrigating fluid, adverse effects of glycine, dilution of the protein and electrolyte concentrations of the body fluids, and disturbance of renal function. The treatment of the TUR syndrome consists of general life support and in specific treatment directed towards hypotension, hyponatraemia and anuria. Methods to lower the uptake of irrigating fluid are widely used and probably reduce the incidence of the TUR syndrome. However, patient safety can be guaranteed only if the absorption is monitored. An irrigating fluid containing tracer amounts of ethanol can be used for this purpose. This permits the uptake of fluid to be indicated by measuring the concentration of ethanol in the patient's exhaled breath.
A comparative study of intravenous and rectal administration of propofol in piglets
Authors: Cozanitis D. A. , Levonen K. , Marvola M. , Rosenberg P. H. , Sandholm M.
Published: January 2009

To compare the effectiveness of propofol given intravenously and rectally, ten piglets received propofol intravenously. On the next day, the same piglets and five other piglets were given suppositories containing propofol. Serial blood samples were collected for the analysis of propofol plasma concentration. The time course of the total plasma drug concentration was fitted into a bi‐exponential function using a least square fitting regression computer programme. The volume of distribution was 2.5–2.8 l‐kg‐1, mean elimination half‐life, 23.9 min and mean clearance 0.08 l‐kg‐1‐min‐1. The mean bioavailability by the rectal route was low. In contrast to the intravenously administered propofol, none of the piglets slept when given propofol rectally, reflecting the extremely low plasma propofol concentration. In veterinary medicine, propofol would seem to be clinically valuable for inducing intravenous anaesthesia, but would be ineffective when given rectally. The findings indicate that with the dosage forms used here, propofol would be clinically ineffective if given rectally to human infants and children.
Effects of pleural fluid and positive end‐expiratory pressure on the measurement of extravascular lung water by the double‐indicator dilution technique
Authors: Blomqvist H. , Wickerts C.‐J. , RÖoUsblad P.‐G.
Published: January 2009

The reliability of the double‐indicator dilution technique (dye/cold) for measuring extravascular lung water (EVLW) has been studied in lung‐healthy dogs after pleural fluid injection of saline (up to 20 ml/kg) during mechanical ventilation at zero and 10 cmH2O (1.0 kPa) end‐expiratory pressure (ZEEP and PEEP, respectively). Pleural fluid injection had no effect on EVLW at either ZEEP or PEEP. PEEP induced changes in cardiac output, and reduced both the intravascular (dye) and the thermal indicator volumes, but with no effect on the calculated EVLW. It is concluded that pleural fluid up to 20 ml/kg and ventilation with PEEP of 10 cmH2O (1.0 kPa) do not affect the reliability of the double‐indicator dilution technique for measuring extravascular lung water in the dog.