Showing papers in "Acta Anaesthesiologica Scandinavica in 1995"

Report of two cases

Abstract: Two patients underwent thoracotomy for resection of pulmonary or esophageal carcinoma. Postoperatively, epidural catheters were inserted for pain management. Complaints of severe injection pain over the abdomen or lower extremities were made during one administration of pain medication. Progressive weakness and numbness developed over the lower trunk and lower extremities, with subsequent respiratory difficulties. Potassium chloride (KCl) was suspected to have been mistaken for normal saline as the diluent for morphine. In addition to endotracheal intubation and ventilatory support, steroids were administered both intravenously and epidurally to suppress spinal cord irritation. The two patients regained motor and sensory functions 14 and 18 hours later, respectively, without sequelae.

Neurological complications after anaesthesia. A follow-up of 18,000 spinal and epidural anaesthetics performed over three years.

Abstract: 17 733 consecutive central blocks (8501 spinal and 9232 epidural anaesthetics) performed during a three-year period were analyzed for alleged complications. Neurological complications related to anaesthesia were reported in 17 cases of which 13 patients had persisting lesions after three spinal and ten epidural blocks. In two patients given spinal anaesthesia, the technique was inadequate. In seven epidural blocks, the connection between neurological lesion and the anaesthetic technique could be argued. In five of these cases, polyneuropathy or nonspecific neurological symptoms were present. Three complications after epidural blocks were paraplegias caused by spinal haematomas in patients with deranged haemostatic capacity.

Central antinociceptive effects of non-steroidal anti-inflammatory drugs and paracetamol. Experimental studies in the rat.

Abstract: Background These studies were undertaken to investigate the site and nature of the antinociceptive effect of NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) and paracetamol in the central nervous system (CNS). Methods Different nociceptive test models were employed: the tail-flick and hot-plate tests (thermoreceptors), the writhing test (visceral chemoreceptors) the "scratching, biting, licking" (SBL) behaviour and the colorectal distension test (mechanoreceptors). Drugs were given intraperitoneally (i.p.), intracerebroventricularly (i.c.v.), intrathecally (i.t.) or as local injection via cannulae implanted stereotactically. Nerve destruction was made by local injection of the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT). Whole brain and spinal cord contents of serotonin and 5-hydroxyindole acetic acid (5-HIAA) were analysed by high pressure liquid chromatography (HPLC). Results Injections of diclofenac induced antinociception in visceral pain models (writhing test, colorectal distension test), but not in two models of somatosensory pain (tail-flick and hot-plate test). The antinociceptive effect of diclofenac (i.p., i.c.v., or i.t.) was reversed by i.p. naloxone. Naloxone also reversed the effect of diclofenac injected locally into thalamic and hypothalamic areas involved in pain transmission as well as in n. paragigantocellularis or n. raphe magnus. In addition, chemical destruction of the n. raphe region attenuated the antinociceptive effect of diclofenac. Inhibition of serotonergic transmission by pretreatment with methiothepin, ritanserin, parachlorophenylalanine (PCPA) or 5,7-DHT also reduced the antinociceptive effect of diclofenac in a visceral pain model. Pretreatment with diclofenac or ibuprofen blocked pain behaviour (SBL) after activation of excitatory amino acid receptors of the NMDA type, but not pain behaviour after activation of AMPA or substance P (SP) receptors. Paracetamol inhibited hyperalgesia after both NMDA and SP. The antinociceptive effects of diclofenac, ibuprofen and paracetamol were reversed by L-arginine, but not by D-arginine. Conclusions The antinociceptive effect of diclofenac involves a central nervous component which may be elicited from several defined areas in the CNS. Part of the antinociceptive effect seems to be mediated by descending inhibitory opioid, serotonin and/or other neurotransmitter systems interfering with visceral pain impulse traffic at the spinal level. NSAIDs and paracetamol interfere with nociception associated with spinal NMDA receptor activation. This effect involves an inhibitory action on spinal nitric oxide (NO) mechanisms. Possibly, the supraspinal antinociceptive effect of NSAIDs may be explained by an analogous action.

Base excess or buffer base (strong ion difference) as measure of a non-respiratory acid-base disturbance

Abstract: Stewart in 1983 (Can J Physiol Pharmacol 1983: 61: 1444) reintroduced plasma buffer base under the name "strong ion difference" (SID). Buffer base was originally introduced by Singer and Hastings in 1948 (Medicine (Baltimore) 1948: 27: 223). Plasma buffer base, which is practically equal to the sum of bicarbonate and albuminate anions, may be increased due to an excess of base or due to an increased albumin concentration. Singer and Hastings did not consider changes in albumin as acid-base disorders and therefore used the base excess, i.e., the actual buffer base minus the buffer base at normal pH and pCO2, as measure of a non-respiratory acid-base disturbance. Stewart and followers, however, consider changes in albumin concentration to be acid-base disturbances: a patient with normal pH, pCO2, and base excess but with increased plasma buffer base due to increased plasma albumin concentration get the diagnoses metabolic (strong ion) alkalosis (because plasma buffer base is increased) combined with metabolic hyperalbuminaemic acidosis. Extrapolating to whole blood, anaemia and polycytaemia should represent types of metabolic alkalosis and acidosis, respectively. This reveals that the Stewart approach is absurd and anachronistic in the sense that an increase or decrease in any anion is interpreted as indicating an excess or deficit of a specific acid. In other words, a return to the archaic definitions of acids and bases as being the same as anions and cations. We conclude that the acid-base status (the hydrogen ion status) of blood and extracellular fluid is described in terms of the arterial pH, the arterial pCO2, and the extracellular base excess. It is measured with a modern pH-blood gas analyser. The electrolyte status of the plasma is a description of the most important electrolytes, usually measured in venous blood with a dedicated electrolyte analyser, i.e., Na+, Cl-, HCO3-, and K+. Albumin anions contribute significantly to the anions, but calculation requires measurement of pH in addition to albumin and is usually irrelevant. The bicarbonate concentration may be used as a screening parameter of a nonrespiratory acid-base disturbance when respiratory disturbances are taken into account. A disturbance in the hydrogen ion status automatically involves a disturbance in the electrolyte status, whereas the opposite need not be the case.

Postdural puncture headache (PDPH): Onset, duration, severity, and associated symptoms: An analysis of 75 consecutive patients with PDPH

Abstract: Among 873 consecutive patients who had undergone a total of 1021 spinal anaesthesias involving puncture of the lumbar dura, 75 (7.35%) complained of Postdural Puncture Headache (PDPH). The severity of each patient's PDPH was categorized, on a scale from mild to severe, on the basis of the onset, duration, severity of the headaches, and the degree to which they were accompanied by auditory and vestibular symptoms. In the patients who developed PDPH, 65% developed symptoms within 24 hours of the lumbar punctures and 92% developed symptoms within 48 hours. For the patients who recovered spontaneously the mean duration of the PDPHs was 5 days, with a range of 1-12 dyas. PDPH was characterized by headaches that were influenced by the patient's posture and the severity of PDPH was categorized as follows: Mild PDPH resulted in a slight restriction of their physical activity. These patients were not confined to bed and had no associated symptoms. Moderate PDPH forced the patient to stay in bed for part of the day, and resulted in restricted physical activity. Associated symptoms were not necessarily present. Severe PDPH. Patients were bedridden for the entire day and made no attempt to raise their head or to stand. Associated symptoms were always present. Forty-five of the PDPH patients (60%) recovered spontaneously. Of these, 8 patients (11%) were categorized as mild cases of PDPH, 14 (19%) as moderate, and 23 (30%) patients as severe cases of PDPH. Thirty of the PDPH patients (40%) were treated with an autologous epidural blood patch (AEBP). Of these, 27 patients (36%) were classified as severe and 3 patients (4%) as moderate PDPH.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic changes due to Trendelenburg positioning and pneumoperitoneum during laparoscopic hysterectomy

Abstract: More prolonged gynecological laparoscopic operations are being performed in recent years, and a steeper head-down position is required. The early reports of hemodynamic changes during gynecologic laparoscopy are conflicting, and the effects of anesthesia, head-down tilt and pneumoperitoneum have not been clearly separated. Invasive hemodynamic monitoring was carried out in 20 female ASA Class I-II patients who underwent laparoscopic hysterectomy. Baseline measurements were made in the supine, supine-lithotomy and Trendelenburg (25-30 degrees) positions in awake patients. Measurements were repeated in the supine-lithotomy and Trendelenburg positions after induction of anesthesia, during laparoscopy 5 minutes after the beginning of peritoneal CO2-insufflation (intra-abdominal pressure 13-16 mmHg) and at 15-minute intervals thereafter, after laparoscopy in the Trendelenburg and supine positions, after extubation and in the recovery room at 30-minute intervals. Patients received balanced general anesthesia with isoflurane in 35% O2 in an oxygen/air mixture. End tidal PCO2 was maintained between 4.5-4.8 kPa (33-36 mmHg) by changing the minute volume of controlled ventilation. The Trendelenburg position in awake and anesthetized patients increased pulmonary arterial pressures (PAP), central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP). These pressures increased further at the start of CO2-insufflation, decreased towards the end of the laparoscopy and reached pre-insufflation levels after deflation of pneumoperitoneum. The mean arterial pressure (MAP) increased at the beginning of laparoscopy in comparison with the pre-laparoscopic values. Heart rate (HR) was quite stable during laparoscopy. The cardiac index (CI) decreased with anesthesia from 3.8 to 3.2 1.min-1.m-2 and further during laparoscopy to 2.7 1.min-1.m-2, returning to pre-insufflation values soon after deflation. The stroke index (SI) changed in concert with the CI changes. The right ventricular stroke work index decreased during laparoscopy more than the left ventricular stroke work index. The right atrial pressure (CVP) exceeded the PCWP more often during laparoscopy than during any other phase of the procedure. Anesthesia and the Trendelenburg position increased the CVP, PCWP and pulmonary arterial pressures and decreased cardiac output. Pneumoperitoneum increased these pressures further mostly in the beginning of the laparoscopy, and cardiac output decreased towards the end of the laparoscopy. The risk of systemic CO2-embolus was increased during laparoscopy.

Sevoflurane for ENT-surgery in children A comparison with halothane

Abstract: Sevoflurane, a new volatile anesthetic agent, is of great potential interest in pediatric anesthesia. Its use for ENT surgery in children was compared with halothane in this study. Altogether 40 children participated in the investigation. In 18 (median age 4.2 years), halothane was used. The remainder (median age 4.0 years) were anesthetized with sevoflurane. After rectal premedication with midazolam and atropine, anesthesia was induced by mask (the agent in O2/N2O, 40/60) using a Mapleson D system. The trachea was intubated without the use of muscle relaxants and the children were then allowed to breathe spontaneously at fresh gas flows set high enough to avoid rebreathing. Hemoglobine oxygen saturation (SpO2), inspired and expired gas concentrations, respiratory rate (RR), heart rate (HR), ECG and blood pressure were followed. Equianesthetic concentrations of the agents were used and induction characteristics were comparable between the two agents. RR and end-tidal CO2 tensions were similar in the two groups. HR and systolic blood pressures were, however, higher with sevoflurane. Cardiac arrhythmias were seen more frequently with halothane (61%) than with sevoflurane (5%). During emergence, postoperative nausea/vomiting was more frequent after halothane anesthesia. Initially, postoperative excitement occurred more often after sevoflurane, when paracetamol was given during anesthesia, which was reduced (P<0.01) when paracetamol was given at the time for premedication. It is concluded that sevoflurane is an excellent induction agent, and maintains heart rate and systolic blood pressure better than when halothane is used. The incidence of cardiac arrhytmia is lower with sevoflurane than with halothane. Sevoflurane anesthesia does, however, result in a high rate of postoperative excitement after ENT surgery, a factor that must be addressed prior to anesthesia.

Neurological complications of central nerve blocks

Abstract: According to frequently cited investigations published 20 to 40 years ago (1-8), transient or permanent nerve lesions are extremely rare complications to spinal and epidural (central) nerve blocks. The current incidence of serious complications seems to remain low as in a combined series of patients undergoing epidural anaesthesia published between 1976 and 1989 comprising a total of 58 407 cases (913) no case was seen of the most feared complication, spinal haematoma. In the case series reviewed by Tryba (1 4), three patients out of 850 000 developed a spinal haematoma following epidural anaesthesia, whereas no case was seen after 650 000 spinal blocks. Metaanalysis estimated the risk for a spinal haematorna to be 0.0007% following epidural anaesthesia and 0.0005% after spinal anaesthesia. A recent very large prospective multieentre study of epidural anaesthesia (1 5), although based exclusively upon an obstetric material, provides further support for the opinion that the technique is associated with a very low risk of neurological complications of 108 events in 505 000 blocks, only five were associated with permanent disability

Reexpansion of atelectasis during general anaesthesia may have a prolonged effect.

Abstract: Pulmonary atelectasis, as found during general anaesthesia, may be reexpanded by hyper-inflation of the lungs. The purpose of this study was to determine whether such a recruitment is maintained and whether this is accompanied by an improved gas exchange. We studied a consecutive sample of twelve lung healthy adults, scheduled for elective surgery. After induction of intravenous anaesthesia, the lungs were hyperinflated manually. The ventilationperfusion relationship (VA/Q) was estimated with the multiple inert gas method, and in six patients atelectasis was assessed by computed x-ray tomography. The mean pulmonary shunt was 7.5% of cardiac output after induction of anaesthesia and this decreased to 1.0% and 2.8% at 20 and 40 min after the recruitment manoeuvre. Perfusion of poorly ventilated lung regions (low VA/Q), however, increased from 3.7% to 10.6% and 7.8% at 20 and 40 min after the recruitment, respectively. The mean alveolar-arterial oxygen tension difference (PA-aO2) was 14.3 kPa after induction of anaesthesia and 11.1 kPa immediately after recruitment. Forty minutes later PA-aO2 was still 2.0 kPa lower than after induction of anaesthesia (95% confidence interval [CI] 0.3 to 3.8 kPa). PA-aO2 decreased more in obese patients. The mean area of atelectasis decreased from 9.0 cm2 after induction of anaesthesia to 0.1 cm2 immediately after recruitment, and there was a slow increase to 1.9 cm2 (95% CI 0.0 to 3.9 cm2) 40 min later. During general anaesthesia in lung healthy patients, most of the reexpanded atelectatic lung tissue remains inflated for at least 40 min. The recruitment manoeuvre decreases pulmonary shunt, but increases low VA/Q. The net effect on gas exchange is a small reduction of PA-aO2.

Effect of intraperitoneal bupivacaine on pain after laparoscopic cholecystectomy

Abstract: The effect of intraperitoneal bupivacaine on postoperative pain was studied in 60 ASA 1-2 patients undergoing elective laparoscopic cholecystectomy. The patients were randomly selected (20 patients in each group) to receive in double-blind fashion 100 mo of either plain 0.15% bupivacaine (150 mg.100 ml-1) or the same solution with adrenaline (1.5 micrograms ml-1), or the same volume of saline into the right subdiaphragmatic space at the end of surgery. The patients were kept in the Trendelenburg's position for 20 min after the instillation. Venous blood samples for the determination of bupivacaine plasma concentrations were drawn up to 180 min. Plasma bupivacaine concentrations peaked at 30 min (highest individual value 2.6 micrograms ml-1) after instillation. Bupivacaine concentrations were significantly lower in the bupivacaine-adrenaline group. During the follow-up no difference between the groups occurred as to the time to first demand of analgesia, severity of postoperative pain, amount of consumed analgesics during 7 days, and length of hospitalization. In all groups, 30-45% of the patients complained of right shoulder pain. After the first 24 hours, pain at rest and during moving was reported as mild and was managed with oral ketoprofen. It is concluded that postsurgical intraperitoneal instillation of 150 mg bupivacaine in 100 ml of saline had no effect on pain after laparoscopic cholecystectomy.

Comparison of cardiac output measurement techniques: thermodilution, Doppler, CO2-rebreathing and the direct Fick method.

Abstract: Simultaneously measured cardiac output obtained by thermodilution (TD), transcutaneous suprasternal ultrasonic Doppler (DOP), CO2-rebreathing (CR) and the direct Fick method (FI) were compared in eleven healthy subjects in a supine position (SU), a sitting position (SI), and during sitting exercise at a workload of 50 W (EX). The agreements between the techniques, two by two, were expressed as the bias calculated as the averaged differences between the techniques. Precision was expressed as the standard deviation of the bias. The overall agreement (bias +/- precision) between TD, DOP and CR respectively and FI were 2.3 +/- 1.6, -0.1 +/- 1.4, and -0.2 +/- 1.1 l/min. TD overestimated cardiac output consistently in SU, SI and EX. DOP was in-accurate during EX and agreed well with FI in SU and SI. CR agreed closely with FI in SI and EX, but values were underestimated in SU. The overall agreement between DOP and CR, respectively, and TD were 2.5 +/- 2.2 and 2.6 +/- 1.6 l/min. The overall agreement between DOP and CR was 0.1 +/- 1.6 l/min. In conclusion, TD overestimated cardiac output compared to the other techniques and the poor agreement has to be taken into consideration especially in measures of low values. The precision of DOP and CR against FI seems to be within clinically acceptable limits, and these methods may provide interchangeable alternatives to the invasive Fick method.

Maternal expectations and experiences of labour pain — options of 1091 Finnish parturients

Abstract: A prospective survey of 1091 Finnish parturients was conducted in order to ascertain mothers' expectations for labour pain relief, to measure the actual pain during all three stages of labour and to question their satisfaction and the adequacy of pain relief on the third day following delivery. Antenatal expectations for pain relief were surveyed. Mothers were questioned on pain levels in the delivery room and 3 days after giving birth. Pain levels were ascertained using a visual pain score method. Antenatally, 90% of all parturients anticipated a need for pain relief during labour. In the delivery room over 80% of all parturients described their pain as very severe to intolerable, only 4% of the multiparous had low pain scores (0-2). After pain treatment 50% of multiparous women still had pain scores from 8 to 10, which reflects a lack of effective pain relief. Dissatisfaction with the childbirth experience was very low, and was associated with instrumental deliveries, but not with the usage of analgesia. 51% of all parturients complained of inadequate pain relief during childbirth, which, in multiparous women, was significantly associated with the second stage of labour.

Central antinociceptive effects of non-steroidal anti-inflammatory drugs and paracetarmol

Abstract: Background: These studies were undertaken to investigate the site and nature of the antinociceptive effect of NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) and paracetamol in the central nervous system (CNS). iVfethods: Diffcrcnt nociceptive test models were employed: the tail-flick and hot-plate tests (thermoreceptors), the writhing test (visceral chemoreceptors) the “scratching, biting, licking” (SBL) behaviour and the colorectal distension test (mechanoreceptors). Drugs were given intraperitoneally (i.p.), intracerebroventricularly (i.c.v.), intrathecally (i.t.) or as local injection via cannulae implanted stcrcotactically. Nerve destruction was made by local injection of the neurotoxin 5,7-dihydroxytryptamine (5,7DHT). FVhole brain and spinal cord contents of serotonin and 5-hydroxyindole acetic acid (5-HIM) were analyscd by high pressure liquid chromatography (HPLC). Results: Injections of diclofenac induced antinociception in visceral pain models (writhing test, colorectal distension test), but not in two models of somatosensory pain (tail-flick and hot-plate test). The antinociceptive effect of diclofcnac (i.p., i.c.v., or i.t.) was reversed by i.p. naloxone. Naloxone also reversed the effect of diclofenac injected locally into thalamic and hypothalamic arcas involved in pain transmission as well as in n. paragigantocellularis or n. raphe magnus. In addition, chemical destruction of the n. raphe region attenuated the antinociceptive effect of diclofenac. Inhibition of serotonergic transmission by pretreatment with methiothepin, ritanserin, parachlorophenylalanine (PCPA) or 5,7-DHT also reduced the antinociceptive effect of diclofenac in a 14sceral pain model. Pretreatment with diclofenac or ibuprofen blocked pain behaviour (SBL) after activation of cxcitatory amino acid receptors of the NMDA type, but not pain behaviour after activation of AMPA or substance P (SP) receptors. Paracetamol inhibited hyperalgesia after both NMDA and SP. The antinociceptive effects of diclofenac, ibuprofen and paracetamol were reversed by L-arginine, but not by D-arginine. Concluszons: The antinociceptive effect of diclofenac involvcs a central nervous component which may be elicited from several defined areas in the CNS. Part of the antinociceptive effect seems to be mediated by descending inhibitory opioid, serotonin and/or other neurotransmitter systems interfering with visceral pain impulse traffic at the spinal level. NSAIDs and paracetamol interfere with nociception associated with spinal NMDA receptor activation. This effect involves an inhibitory action on spinal nitric oxide (NO) mechanisms. Possibly, the supraspinal antinoceptive effect of NSAIDs may be explained by an analogous action. Ki words: Antinociception, experimental pain, visceral pain, microinjections, serotonin, nucleus raphe magnus, NRM, spinal cord, E M , NMDA, AMPA, substance P, arginine, diclofenac, ibuprofen, paracetamol. 0 Acta Anaesthesiologtca Scandmauaca 39 (1 995) This thesis is based on the following papers which will be referred to in thc text by Roman numerals. 1. Bjorkman, R, Hedner, J, Hedner, T, Henning M. Central, nalonone-reversible antinociception 4 diclofoiac in the rat. Naunyn-Schmiedeberg’s Arch Pharm, 342, 171-176, 1990 11. Bjorkman, R, Hallman, K, Hedner, J, Hedner, T, Henning M. Localization of the central antinociceptive fj c t s ofdiclofenac in the rat. Brain Res 590, 66-73, 1992 111. Bjorkman, R, Hallman, K, Hedner, J, Hedner, T, Henning M. Antinociceptive eJects of diclofenac, a NanSteroidal Anti-Injammatoy Drug, interaction with central serotonergic mechanisms. (Submitted for publication) IV. Bjorkman, R, Hallman, K, Hedner, J, Hedner, T, Henning, M. Acetaminophen blocks spinal hyPeraLgesia induced ty NMDA and substance I? Pain, 57, 259-64, 1994 Bjorkman, R, Hallman, K, Hedner, J, Hedner, T, Henning, M. Hyperalgesia induced b j intrathecal JVMDA, but not substance P and AMPA zj. modulated 4 JVon-Steroidal Anti-Injamrnato?y Drugs (NSAIDs) in the rat. (Submitted for publication) V. 0 Bcla Anaesthesiologica Scandinauica 39 ( I 995)

Thoracic paravertebral analgesia

Abstract: Thoracic paravertebral nerve blockade, although once widely practised, has now only a few centres which contribute to the literature. Data production has, however, continued and this review correlates this new information with existing knowledge. Its history, taxonomy, anatomy, indications, techniques, mechanisms of analgesia, efficacy, contraindications, toxicity, side effects and complications are reviewed. Thoracic paravertebral analgesia is advocated for surgical procedures of the thorax and abdomen, especially wherever the afferent input is predominantly unilateral eg. thoracotomy, cholecystectomy and nephrectomy. It is also of benefit in the prevention and management of chronic pain. It is a simple undertaking with impressive efficacy. Plasma local anaesthetic levels are acceptable and its side effect and complication rates are low. No mortality has been reported. For unilateral surgery of the chest or trunk, thoracic paravertebral analgesia should be considered as the afferent block of choice. For bilateral surgery, its efficacy may be limited by the doses of local anaesthetic which could safely be used and further study in this area in particular is required. This form of afferent blockade deserves greater consideration and investigation.

Contribution from upper and lower airways to exhaled endogenous nitric oxide in humans.

Abstract: Endogenous nitric oxide (NO) is thought to regulate many biological functions, including pulmonary circulation and bronchomotion, and it has been found in exhaled air. Our aim was to study the excretion of NO in different parts of the respiratory system. Exhaled concentrations of NO were measured by chemiluminescence in chronic tracheostomy outpatients (group 1), in patients admitted for minor abdominal surgery (group 2), and in patients with acute respiratory failure (ARF) during mechanical ventilation (group 3). In awake volunteers (group 4), 0.57 L/min gas was aspirated through the nasal cavity into the chemiluminescence device. In group 1 (tracheostomy, n=5) we detected 16±2 (mean±s.c. mean) parts per billion (ppb) NO when exhaling through the mouth, and a lower (P<0.05) value of 4.6±0.8 ppb NO when exhaling through the tracheostomy. Before anaesthesia, group 2 (n=11) exhibited 13±2.4 ppb NO in orally exhaled gas, increasing considerably during exhalation through the nose. Upon endotracheal intubation exhaled NO concentration dropped to 1.3±0.2 ppb (P<0.05). In group 3 (ARF, n=7) tracheal NO concentrations were 0.8±0.2 ppb. In group 4 (volunteers, n=6) 394±23 ppb NO was recorded in air from the nasal cavity. In both healthy subjects and patients with respiratory failure a significant NO excretion occurs in the lower airways and lungs. The upper airways, expecially the nose, contribute the largest amount of NO (>90%) to exhaled air. The physiological implications of an upper airway source of NO remain to be defined.

Perioperative monitoring of neuromuscular transmission using acceleromyography prevents residual neuromuscular block following pancuronium

Abstract: The frequency of postoperative residual neuromuscular block following the use of the long-acting non-depolarizing muscle relaxants is high, and manual evaluation of the response to nerve stimulation does not eliminate the problem. In this prospective and randomized study we evaluated the hypothesis that perioperative use of acceleromyography would allow for a more rational and precise administration of the long-acting muscle relaxant pancuronium resulting in a decrease in 1) the incidence and severity of postoperative residual neuromuscular block, 2) the amount of pancuronium used, and 3) the time from end of surgery to tracheal extubation. Forty adult patients were randomized into two groups, one managed without the use of a nerve stimulator, the other monitored using train-of-four (TOF) nerve stimulation and acceleromyography. All patients were anaesthetized with diazepam, fentanyl, thiopentone, nitrous oxide, and in some patients halothane, and they all received pancuronium 0.08-0.1 mg kg -1 for tracheal intubation, and 1-2 mg for maintenance of neuromuscular block. Neostigmine 2.5 mg preceded by atropine I mg was administered for reversal. In the patients managed without a nerve stimulator, the trachea was extubated when the anaesthetist judged the neuromuscular function to have recovered adequately for upper airway protection and spontaneous ventilation. In patients monitored with acceleromyography, the trachea was extubated when the TOF ratio was above 0.70. In all 40 patients, TOF ratio was measured using mechanomyography immediately after tracheal extubation and the patients were evaluated for clinical signs of residual neuromuscular block. Train-of-four ratios, as measured mechanically, varied between 0.26 and 0.96 (median 0.65) in the group not monitored during the operation with acceleromyography. Seven patients in this group were unable to sustain head lift for 5 seconds and five patients were unable to lift an arm to the opposite shoulder, as compared to 1 and 0 patients, respectively, in the group monitored using acceleromyography (P<0.05). The time from end of surgery to tracheal extubation varied between 0 and 25 min (median 10 min) in the group not monitored as compared to 7-47 min (median 15 min) in the monitored group (P<0.01). There was no statistically significant difference in the total dose of pancuronium given in the two groups. It is concluded, that by using acceleromyography during anaesthesia it is possible to avoid the problem of residual neuromuscular block following pancuronium. However, in this study this happened at the expense of a slightly prolonged recovery time (5 min longer). Under the conditions of the study the use of acceleromyography did not influence the amount of pancuronium used during anaesthesia.

Pharmacology of flumazenil

Abstract: Flumazenil, an imidazobenzodiazepine, is the first benzodiazepine antagonist available for clinical use. It is a specific competitive antagonist at benzodiazepine receptors, which are associated with receptors for gamma-aminobutyric acid, the most important inhibitory neurotransmitter in the central nervous system. Administered orally, it has a low bioavailability and the preferred route is intravenous. Its usual clinical role is to reverse the effects of benzodiazepine sedation; however, administered before, or with, other benzodiazepines, it modifies their effects, the extent of such modification depending on the dose, duration of effect and relative receptor affinity of the agonist. Flumazenil also reverses adverse physiological effects of benzodiazepines. Its indications include reversal of benzodiazepine-induced sedation, termination of benzodiazepine-induced anaesthesia, return of spontaneous respiration and consciousness in intensive care patients and the treatment of paradoxical reactions to benzodiazepines. Other potential indications include its use in hepatic encephalopathy, alcohol intoxication and coma; however, these claims still require substantiation. Following sedation reversed with flumazenil, minimal residual effects of the agonist can sometimes be detected using psychomotor tests and are due to the relatively short half-life of flumazenil, but are of no clinical consequence. There is concern that flumazenil could precipitate an acute withdrawal syndrome following long-term benzodiazepine administration; however, the available evidence suggests otherwise and that it could be useful in the treatment of benzodiazepine tolerance. The existence of flumazenil is important, with implications for future research and the development of minimally invasive therapy and day-case surgery. With increasing pressures on non-anaesthetically trained practitioners to perform sedation, flumazenil has important implications for safety.

Phenylephrine in treating maternal hypotension due to spinal anaesthesia for caesarean delivery: effects on neonatal catecholamine concentrations, acid base status and Apgar scores.

Abstract: Maternal and neonatal catecholamine concentrations, following the use of either phenylephrine or ephedrine to treat a drop in maternal blood pressure after spinal anaesthesia for caesarean delivery, were compared. Patients were randomly assigned to one of two groups: Group 1 patients (n = 20) were treated with ephedrine given as 5 mg intravenous bolus injections; Group 2 patients (n = 20) were treated with phenylephrine given as 40 micrograms intravenous bolus injections, for decreases in maternal systolic blood pressure to maintain maternal systolic blood pressure above 100 mmHg. Maternal vein (MV), umbilical vein (UV), and umbilical artery (UA) blood samples were taken at the time of delivery. Samples were analyzed for catecholamine concentrations and blood gas values. Noradrenaline concentrations in UA, UV and MV (at delivery) samples were significantly higher in group 1 compared to group 2; they were 6858 +/- 3689 vs 1674 +/- 944 pg.ml-1 (P < 0.0001), 1265 +/- 758 vs 395 +/- 470 pg.ml-1 (P < 0.001) and 239 +/- 165 vs 103 +/- 93 pg.ml-1 (P < 0.01), respectively. Comparing blood gas values between groups 1 and 2, statistically significant differences were observed in UA pH (7.28 +/- 0.01 and 7.32 +/- 0.01 pH units, P = 0.01), UA pCO2 (7.32 +/- 0.24 and 6.68 +/- 0.21 kPa, P = 0.03), UA base excess (2.2 +/- 0.4 and 0.9 +/- 0.4 mmol.1-1, P = 0.04) and UV base excess (2.0 +/- 0.3 and 0.7 +/- 0.3 mmol.1-1, P = 0.004). No significant differences in maternal characteristics, acid base values, incidence of nausea and vomiting, and Apgar scores were observed between groups. Phenylephrine appears to be as safe and effective as ephedrine in treatment of drop in blood pressure in healthy non-labouring parturients undergoing caesarean delivery. The use of phenylephrine was also associated with significantly lower noradrenaline concentrations in both mother and neonate.

Control of post anaesthetic shivering with nefopam hydrochloride in mildly hypothermic patients after neurosurgery.

Abstract: Postoperative shivering may be prevented by maintaining normothermia intraoperatively or it may be treated using specific drugs. The aim of this study was to compare the efficacy of nefopam hydrochloride (nefopam) to that of clonidine and meperidine in patients undergoing elective neurosurgical procedures. Three groups of patients were included in the study. Patients in group A (60) received i.v., at random, 20 mg of nefopam, 50 mg of meperidine or 150 micrograms of clonidine in the immediate postoperative period. The incidence of shivering and the time at which shivering ceased were noted, along with central temperature and main haemodynamic changes. Group B (20) received i.v., at random, either 10 mg of nefopam or saline before awakening from anaesthesia. The effects of nefopam on central temperature, oxygen consumption (Vo2), carbon dioxide production (VcO2), basal metabolic rate (BMR) and energy expenditure (EE) were investigated. Group C (10) received i.v. 20 mg of nefopam during surgery: cerebrospinal fluid pressure (CSFP), cerebral perfusion pressure (CPP) and electroencephalogram (EEG) were monitored. In group A nefopam stopped shivering in 95% of patients when compared to meperidine and clonidine, which were effective in 32% and 40% of patients respectively. In group B, only 10% of patients receiving nefopam had postoperative shivering, Vo2, VcO2 and EE were significantly lower in patients treated with nefopam than those in the control group. No changes in CSFP, CPP or EEG were observed in group C. In conclusion, nefopam seems to be more effective than clonidine or meperidine in quickly suppressing shivering, without producing significant adverse reactions.

Fentanyl attenuates cardiovascular responses to tracheal extubation

Abstract: We carried out a controlled, randomized, double-blind study to examine the effects of intravenous fentanyl (1 or 2 micrograms kg-1) on hemodynamic changes during tracheal extubation and emergence from anesthesia in 60 ASA physical status I or II patients undergoing elective gynecological surgery. Anesthesia was maintained with 0.5%-1.5% isoflurane and 60% nitrous oxide (N2O) in oxygen. Muscle relaxation was achieved with vecuronium. The patients were randomly assigned to three group (each, n = 20), and fentanyl (1 or 2 micrograms kg-1), or saline (as a control) was given at the time of peritoneal closure. Changes in heart rate (HR) and blood pressure (BP) were measured during and after tracheal extubation. Adverse effects, including postoperative sedation and respiratory depression, were also assessed. The HR, systolic BP, and diastolic BP increased significantly during tracheal extubation in the control group (P < 0.05). Fentanyl 2 micrograms kg-1 attenuated the increases in these variables more effectively than fentanyl 1 microgram kg-1. The time interval from the study drug to extubation was similar in each group. Postoperative somnolence and respiratory depression were not observed in any patients in any of the three groups. We concluded that a bolus dose of intravenous fentanyl 2 micrograms kg-1 given at the time of peritoneal closure was of value in attenuating the cardiovascular changes associated with tracheal extubation and emergence from anesthesia, and that this treatment did not prolong the recovery. However, further studies are required to assess this technique in patients with cardiovascular or cerebrovascular diseases.

A prospective survey of postoperative nausea and vomiting with special regard to incidence and relations to patient characteristics, anesthetic routines and surgical procedures

Abstract: We performed a prospective study on 421 patients subjected to routine general-, orthopaedic-, urologic-, gynecological and paediatric surgery to estimate the current incidences of nausea and vomiting during the first 24 hours after surgery The overall incidences of postoperative nausea or vomiting were 17% and 28%, respectively Postoperative emetic symptoms were not related to age in adults Women had more often emetic symptoms than men (P<001) In general, opiate premedication was more frequently associated with postoperative nausea and vomiting than benzodiazepines (P<001), but in otherwise comparable subgroups of patients undergoing major surgery, this difference was not confirmed Balanced general anaesthesia caused more nausea (23%) and vomiting (53%) than face-mask anaesthesia (13% and 15%, respectively) or regional blocks (12% and 7%, respectively) (P<0001) There was a positive correlation between the duration of anaesthesia and the incidence of postoperative emetic symptoms (P<0001) The incidences of postoperative nausea and vomiting after abdominal surgery were 23% and 58% respectively Corresponding figures for orthopaedic surgery were 25% and 34%, other kinds of extra-abdominal surgery 18% and 32% and for laparoscopy 21% and 25% After minor gynecological-, urological-and paediatric surgery the incidences were less than 20% In conclusion female gender, balanced anaesthesia, lengthy duration of anaesthesia, and abdominal and orthopaedic operations appeared to be most frequently associated with postoperative emetic symptoms

Determination of oxygen consumption in muscle during exercise using near infrared spectroscopy.

Abstract: The aim of this study was to determine oxygen consumption (VO2) during isometric exercise in human muscles using near infrared spectroscopy (NIRS). The technique was used to study the relationship between VO2 in the soleus muscle and the level of isometric exercise expressed as percentages of the maximum voluntary contraction (MVC). For the study 11 healthy male volunteers were recruited. Reproducibility was studied in 6 subjects. The subjects were seated in a chair with the knee joint at an angle of 90 degrees. The optodes of the NIRS instrument were attached to the lateral aspect of the soleus muscle. A horizontal bar above the knee was connected to a dynamometer. Subjects applied isometric force to the bar by producing a torque at the ankle joint. Firstly the MVC was determined. Secondly the VO2 at rest and at 5 levels of isometric exercise, ranging from 5% to 25% of MVC and increasing by 5% each stage, was measured. In all cases the VO2 at rest or during isometric contraction was determined from the decrease of the oxyhaemoglobin (O2Hb) signal immediately after arterial occlusion of the thigh. Repeated measurements showed no significant difference between trials, indicating that the measurements were reproducible. At rest a VO2 of 6.7 +/- 1.1 microMO2Hb.min-1 (mean +/- S.E.M.) was found, a result comparable with other studies. In all subjects a linear relationship was found between the VO2 and the level of exercise. The average slope of the regression lines of all individuals was 0.85 +/- 0.22 microMO2Hb.min-1.%MVC-1 (mean +/- S.E.M.). Inter-individual variation of the slopes was high and ranged from 0.28 to 2.29 microMO.Hb.min-1.%MVC-1, which can be explained by differences in fat percentage and in the measuring volume of the NIRS instrument. NIRS appeared to be a reproducible and reliable method for the non-invasive measurement of VO2 in human muscles. The method could be used to investigate regional differences as well as changes in time between muscle groups as a function of training.

Death associated with anaesthesia and surgery in Finland in 1986 compared to 1975.

Abstract: Mortality associated with anaesthesia and surgery in Finland in 1986 was studied using a retrospective method and was compared with the results of a similar study performed in 1975. The total number of procedures was 325 585. 570 patients fulfilled one of the three criteria: 1. The patient died within three days of a procedure needing anaesthesia. 2. The patient died more than three days after a procedure needing anaesthesia, but had suffered a cardiac arrest or been resuscitated, or there was a surgical or an anaesthesiological complication contributing to the death. 3. The patient suffered a major handicapping neurological (or other) deficit, which was associated with anaesthesia, or there was a surgical or an anaesthesiological complication possibly contributing to the death or handicap (no patients). The number of consultant anaesthesiologists had more than doubled since 1975. At the same time there was also a significant increase in recovery room and intensive care facilities. Surgery-was the main contributing factor in the death of 22 (frequency 0.68/10 000 procedures), and anaesthesia in the death of five (frequency 0.15/10 000 procedures) patients. The role of surgery had decreased to about one third and the role of anaesthesia to less than one tenth as the main cause of death associated with anaesthesia and surgery compared to the year 1975. 95.3% of all the patients died mainly because of co-existing medical or surgical disease.

Desflurane analgesia for vaginal delivery.

Abstract: The use of subanaesthetic concentration of inhalational anaesthetic for vaginal delivery offers many advantages to the mother and newborn. Desflurane, with the characteristics of rapid onset and minimal metabolism, may provide better analgesia and safety for labour pain control. Eighty healthy parturients were randomly assigned to receive either desflurane 1.0-4.5% and oxygen (n = 40) or nitrous oxide 30-60% in oxygen (n = 40). Analgesia was assessed using a score from 0 (no relief) to 4+ (excellent analgesia), amnesia for the delivery, blood loss were recorded. Neonates were evaluated by Apgar scores and neurologic and adaptive capacity scores (NACS). Data were analyzed for statistical significance using Student's t-test or Chi-square when appropriate. Analgesia scores were similar for both groups with more amnesia in desflurane group (23% vs 0% P < 0.05). Blood loss did not differ significantly, 364 ml for the desflurane group and 335 ml for the nitrous oxide group. There were no significant differences for neonatal Apgar score at 1 min or at 5 min or the NACS at 2 hr or 24 hr between the two groups. We conclude that desflurane in subanaesthetic doses is safe and effective inhalation agent for normal delivery but might be associated with amnesia.

Comparison of vascular effects of ropivacaine and lidocaine on isolated rings of human arteries.

Abstract: Ropivacaine is a new local anaesthetic agent. Previous animal studies have indicated that vasoconstrictor effects are elicited by ropivacaine in vitro and subcutaneously and that it produces blanching of the skin if injected subcutaneously in humans. Lidocaine is a widely used local anaesthetic reported to exert a biphasic effect on the microvasculature with contraction at low concentrations and relaxation at high concentrations. There is a need for pharmacologic tools able to counteract local arterial vasoconstriction. In this study, the contractile effect of ropivacaine and lidocaine were investigated in vitro on isolated human arteries. Experiments were performed on 43 internal mammary artery (IMA) rings obtained from 22 patients and on 14 radial artery (RA) rings from 7 patients. The rings were mounted in organ baths and isometric contractile activity was measured. Experiments were conducted by cumulative adding ropivacaine or lidocaine (1.5 x 10(-5) M; 4.5 x 10(-5) M; 1.5 x 10(-4) M; 4.5 x 10(-4) M; 1.5 x 10(-3) M; 4.5 x 10(-3) M; 1.5 x 10(-2) M) to the organ baths. The endothelium was mechanically removed in 19 IMA rings and in 9 RA rings. Ropivacaine and lidocaine produced a biphasic response with contraction at low concentrations (1.5 x 10(-5)-1.5 x 10(-3) M) and release of the maximal contraction at higher concentrations. No statistically significant differences in contractile or relaxing effects were seen between the two drugs. Removal of the endothelium did not significantly affect contractile activity. In this study of human mammary artery preparations, ropivacaine is not a stronger vasoconstrictor than lidocaine.

Identification of human plasma cholinesterase variants in 6,688 individuals using biochemical analysis

Abstract: In 1973, a Cholinesterase Research Unit was established in Denmark (DCRU). The primary aim was to provide a central service for determining genotypes and activity of plasma cholinesterase (BChE) in patients showing abnormal response after succinylcholine. The purpose of the present study was, on the basis of 20 years experience with this Unit, to establish accurate reference intervals for BChE activity and inhibition values for the different genotypes of BChE. Also we wanted to evaluate the influence of age and sex on the BChE activity in genotypically normal patients. Plasma cholinesterase activity was measured using benzoylcholine as substrate. The genetic variations of the enzyme were identified using differential inhibitors, i.e.: Dibucaine, Sodium Fluoride, Succinylcholine, Urea and Ro-2-0683. We investigated 6,688 patients. The reference values for the 13 genotypes represented agree with previous findings. In genotypically normal patients, no age or sex differences were found in BChE activity in children below the age of 10 years. From the age of 10 years the activity decreased significantly in both males and females, the activity in females being significantly lower than in males. In females the activity was lowest in the age group 30-40 years, returning to prepuberty level at about 60 years of age. In males the activity decreased slightly up to 50-60 years of age. Hereafter the activity was stable or tended to increase slightly. Most genotypes could be recognized using the results of the different inhibition studies. We found the inhibitors Dibucaine, Sodium fluoride, Urea and Ro-2-0683 most helpful, whereas succinylcholine was of less value.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypotensive treatment with α2-agonist and β1-antagonist on cerebral haemodynamics in severely head injured patients

Abstract: Therapy of post-traumatic brain oedema often includes preservation of high arterial blood pressure to avoid secondary ischaemic injuries to the brain. This practice can be questioned since high arterial blood pressure may aggravate brain oedema through raised hydrostatic capillary pressure, causing fluid filtration across the damaged blood-brain barrier. This latter view is in agreement with our clinical experience and therefore hypotensive therapy with an alpha 2-adrenergic agonist (clonidine) and a beta 1-adrenergic antagonist (metoprolol) has become part of our treatment protocol for severely head injured patients to decrease the post-traumatic brain oedema. The present study is an attempt to analyse whether there are any direct local cerebrovascular effects of the hypotensive agents used, which also might influence intracranial pressure. Severely head injured patients were investigated. Heart rate, mean arterial blood pressure, intracranial pressure, cerebral blood flow and arteriovenous difference in oxygen content were measured before and after a bolus dose of clonidine (six patients) and metoprolol (nine patients). Clonidine decreased mean arterial blood pressure and cerebrovascular resistance without affecting other parameters measured. Metoprolol decreased heart rate and mean arterial pressure, but had no effect on the cerebrovascular parameters. The results show that clonidine and metoprolol have no, or only minor, direct influence on local cerebral haemodynamics in severely brain injured patients. This implies that if there is an intracranial pressure reducing effect of these drugs, as suggested, this must be due to other mechanisms, namely a reduction in capillary hydrostatic pressure secondary to decreased arterial blood pressure and heart rate.

Permissive hypercapnia in ARDS and its effect on tissue oxygenation.

Abstract: Many experimental studies have shown that mechanical ventilation with high tidal volumes (Vt) or with a low end-expiratory volume allowing repeated end-expiratory collapse, can result in acute parenchymal lung injury and probably an inflammatory response. Low volume ventilation with permissive hypercapnia has been used in an attempt to avoid such injury in ARDS. Such management can affect oxygenation in many complex ways. The right-shift of the haemoglobin-oxygen dissociation curve during acute respiratory acidosis may increase venous oxygen tension (PvO2) which could allow increased O2 uptake in ischaemic tissues. Acidosis may reduce intrapulmonary shunt (Qs/Qt) by potentiating hypoxic pulmonary vasoconstriction, and there may also be direct and autonomically mediated effects of hypercapnia both on the lung vasculature and on the airways. Cardiac output usually increases as a consequence of hypercapnia and perhaps as a result of reduced intrathoracic pressure, further increasing PvO2 and CvO2, but the increase in cardiac output (CO) may tend to increase Qs/Qt as flow increases preferentially in unventilated lung. The reduction of mean airway pressure may directly increase Qs/Qt. Hypercapnia may affect the distribution of systemic blood flow both within organs and between organs. Limited clinical studies suggest that tissue oxygenation is usually unchanged or improved during permissive hypercapnia with increased CO, reduced arterio-venous O2 content difference and reduced blood lactate concentration. However, acute hypercapnia per se can reduce lactate production. Further studies are required of this complex issue.

Post dural puncture headache

Abstract: We describe the delayed diagnosis and management of a spinal headache following the use of a 24 g Sprotte needle, the results of a survey of spinal needle usage by physicians in the south west of England and a review of the prevention and management of postdural puncture headache.

Desflurane: a new volatile anesthetic for cesarean section. Maternal and neonatal effects

Abstract: Desflurane, a new volatile anesthetic agent with low blood/gas solubility, has recently been studied in clinical and animal trials but its use in obstetrics has not been adequately evaluated. This prospective study was undertaken to evaluate the maternal and neonatal effects of desflurane in obstetrical patients. Seventy-five healthy parturients undergoing primary or repeat cesarean section were randomly assigned to one of three groups of 25 each, end-tidal 3% desflurane, 6% desflurane or 0.6% enflurane, combined with 50% N2O and O2. All patients had rapid sequence induction of anesthesia with thiopentone sodium followed by succinylcholine for tracheal intubation. After delivery, anesthesia was maintained with reduced concentration of desflurane or enflurane with 67% N2O in O2, supplemented by butorphanol tartrate. Maternal hemodynamic parameters, blood loss and maternal awareness during surgery were monitored. Neonatal outcome was evaluated by Apgar scores, neurological and adaptive capacity scores (NACS), cord blood gas and acid-base status, and time to sustained respiration (TSR). Maternal blood loss did not differ significantly between the three groups and none of the patients developed intraoperative awareness. All three groups responded to psychomotor performance equally fast. Patients in all three groups developed transient hypertension and tachycardia during induction of anesthesia which returned to baseline values in approximately 5 min. Neonatal outcome was equally good in the three groups. More neonates in the 6% desflurane group had TSR > 90 s compared to the 3% desflurane group (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)