Background and objective: Children are vulnerable to regurgitation with a relatively high incidence of aspiration during general anaesthesia which is attributed to the high intragastric pressure, a short oesophagus, an immature laryngeal reflex and incomplete lower oesophageal sphincter muscle function. Subcutaneous administration of epinephrine is generally used in surgery to decrease bleeding due to local vasoconstriction. The effect of epinephrine on the sphincter muscle tone was investigated during general anaesthesia in children.

Methods: Ten children scheduled for skin graft or plastic surgery of the ear were studied. A gastrointestinal pressure sensor was inserted nasally, and the intraluminal pressures of the lower oesophagus, lower oesophageal sphincter and stomach were monitored under sevoflurane, nitrous oxide anaesthesia. The effect of epinephrine on the lower oesophageal sphincter muscle tone was measured.

Results: The resting pressure of the lower oesophageal sphincter muscle tone significantly decreased from 4.56 ± 1.85 to 3.79 ± 1.11 kPa after 3 μg kg−1 epinephrine for 4 min. The barrier pressure is the difference between the lower oesophageal sphincter and intragastric pressure, and that decreased to 1.23 ± 1.17 kPa from the 2.07 ± 1.77 kPa resting level. The observations implied that epinephrine had a long-lasting relaxing effect on lower oesophageal sphincter muscle in children.

Conclusions: The observations may give some explanation about the mechanism of gastro-oesophageal reflux during general anaesthesia, especially in the participation of the adrenergic receptors.

Cardiovascular responses after epidural alkalinized lignocaine and subarachnoid hyperbaric bupivacaine administration were studied using a non-invasive cardiac output measurement in 32 ASA Grade I–II patients undergoing orthopaedic leg surgery (hip hemi-arthroplasty or Ender nailing). All patients achieved adequate surgical anaesthesia. The block onset time was faster (P = 0.003), and the range of final sensory level wider (P = 0.006) in patients receiving spinal anaesthesia compared with the epidural group. Diastolic arterial pressure was significantly reduced when compared with base-line (P = 0.002) only in the spinal group. No significant changes in stroke volume, systemic vascular resistance or left ventricular stroke work were observed in either group. Heart rate and cardiac index were significantly reduced in the spinal group when compared both with base-line (P = 0.002; P = 0.04) and the epidural group (P = 0.001; P = 0.006). The results demonstrated that the block onset time and the cardiovascular effects produced by lumbar epidural anaesthesia, with alkalinized solutions, remain less than after spinal anaesthesia involving the same segments.

Gamma hydroxybutyric acid, a central inhibitory neurotransmitter and a cerebral metabolite of gamma-aminobutyric acid, is present in high concentrations in the mammalian hypothalamus and basal ganglia. Its sodium salt gamma hydroxybutyrate has been effectively used as an intravenous anaesthetic agent, and as an oral sedative, and in the management of the alcohol withdrawal syndrome. In an animal model, using 72 Wistar strain rats allocated to one of six groups of 12 animals each, with implanted lumbar intrathecal catheters, we examined whether gamma hydroxybutyrate, 20% 40 μL (32 mg kg−1) administered alone or combined with fentanyl, gamma hydroxybutyrate 20% 20 μL (16 mg kg−1), fentanyl 0.005% 20 μL (4 mg kg−1) as an intrathecal bolus, provides intra-operative anaesthesia, comparable with that produced by intrathecal lignocaine. We demonstrated that gamma hydroxybutyrate, given by an intrathecal bolus in the rat model, produced reversible segmental antinociception, together with muscular relaxation of the abdominal wall and rear limbs. This is accompanied by moderate sedation without haemodynamic or respiratory depression. This agent may thus be promising for use as a spinal anaesthetic drug.

Summary

Background and objective: The Datex-Ohmeda neuromuscular transmission module (M-NMT)® is a new monitor that is part of the AS/3® anaesthesia monitor. It incorporates a mechanosensor, which is a piezoelectric polymer attached to the hand. The module was compared with a force transducer in 30 patients requiring neuromuscular blockade.

Methods: Anaesthesia was induced with fentanyl and propofol, and tracheal intubation was performed without muscle relaxants. Neuromuscular blockade was assessed by the test module on one arm and the force transducer on the other arm. When the response to train-of-four stimulation had been stable in both arms for 3 min, rocuronium 0.2 mg kg−1 was injected intravenously. During recovery from blockade, the train-of-four ratio was measured in 15 patients, and the ratio of response to double-burst stimulation in the other 15 patients. Data analysis was by difference plots.

Results: Both devices had acceptable coefficients of repeatability. The M-NMT® module was biased by +1.3% (upper limit of agreement 14.2%, lower limit −12.9%) for the recovery of the train-of-four ratio, and by +1.09% (17%, −16%) for the recovery of double-burst stimulation ratio.

Conclusions: The Datex-Ohmeda M-NMT® gives measurements that are repeatable and gives good enough correspondence with a force transducer that it can be used clinically to assess recovery of neuromuscular blockade, but the limits of agreement rule out research applications.

Summary

Although local anaesthesia is mentioned in historical manuscripts, it is only a hundred years since Bier first reported the intrathecal use of local anaesthetic agents. This has been followed by a rapid progression in the art and science of spinal anaesthesia. Isomerically pure agents with favorable clinical profiles, such as ropivacaine and levobupivacaine are now available. Spinal anaesthesia is commonly used in a variety of situations, including orthopaedic, abdominal, gynaecological surgery, Caesarean section and the relief of pain in childbirth. Hyperbaric solutions of local anaesthetics appear to produce more consistent results than plain solutions and the addition of other drugs, such as opioids and clonidine may improve analgesia. In addition to traditional spinal anaesthesia, local anaesthetics are now being evaluated in continuous spinal anaesthesia and combined epidural–spinal anaesthesia. This article reviews clinical experience with levobupivacaine and ropivacaine. Compared with levobupivacaine, ropivacaine generally produces a less intense motor block of shorter duration, which has advantages for earlier mobilization and discharge from hospital and may be particularly useful in obstetrics and ambulatory surgery.

The concentrations of nitrous oxide, sevoflurane and oxygen in the circle system of a closed-circuit anaesthesia machine, the PhysioFlex™, were measured in seven patients. During anaesthesia, the settings for each gas were changed and their concentrations recorded. At the induction of anaesthesia, it took 80– 510s (median 190 s) for the end-tidal sevoflurane concentration to reach 2.0%, and 920–2640 s (median 1500 s) for the oxygen in the breathing circuit to reach 30%. At this time, the nitrous oxide concentration was 60±3% (mean±SD). During anaesthesia, it took 90–480 s (median 140 s) for the end-tidal sevoflurane concentration setting to decrease from 3.0 to 1.0%, and 90–400 s (median 110 s) to return from 1.0 to 3.0%. When the inspired oxygen was increased from 30 to 50%, circuit concentrations reached equilibrium in 40–60 s (median 40 s), and when decreased from 50% back to 30%, equilibrium took 310–470 s (median 450 s). During recovery from anaesthesia, inspiratory sevoflurane concentration took 40–70 s (median 50 s) to decrease to 0.2%. The PhysioFlex™ provided adequate control of sevoflurane and oxygen concentrations, but not of increasing nitrous oxide concentrations.

Hereditary angio-oedema is an autosomal dominant condition resulting in a deficiency of C1 esterase inhibitor protein in serum. The condition is characterized by oedematous attacks in the skin, mucous membranes and gastrointestinal tract triggered by mental and physical stress. We present the rare case of a young girl with known hereditary angio-oedema and spina bifida occulta being admitted for an elective pilonidal sinus excision. This case presented different challenges for the anaesthetists and surgeons.

A case of recurarization in the recovery room is reported. Accumulation of atracurium in the intravenous line led to recurarization after flushing the line in the recovery room. A respiratory arrest with severe desaturation and bradycardia occurred. Circumstances leading to this event and the mechanisms enabling a neuromuscular blockade to occur, following the administration of a small dose of relaxant, are discussed.

Summary

Risk-adjusted outcome prediction is mainly important in two separate fields. The first is quality monitoring: measuring actual versus predicted mortality in an institution allows assessment of the clinical surgical and anaesthesia performance while adjusting for the risk profile of the patients. Without risk stratification, surgeons and hospitals treating high-risk patients will appear to have worse results than others. This may prejudice referral patterns, affect the allocation of resources and even discourage the treatment of high-risk patients. The second field is that of informed consent and clinical decision-making. Risk-adjusted predicted mortality should form an important part of patient and surgeon decisions on whether or not to proceed with surgery. Clearly, no ‘perfect’ model can be produced as some aspects of mortality will always be related to risk factors not included in the model (e.g. the quality of the distal coronary artery vessels in coronary artery surgery) or due to chance happenings not related to preoperative patient characteristics (such as surgical error). An individual patient will either survive or die after cardiac surgery. Clearly, no scoring system will predict the specific outcome for every patient. However, risk stratification will inform patients and clinicians of the likely risk of death for a group of patients with a similar risk profile undergoing the proposed operation. This information is useful and should form part of the basis on which the patient and surgeon decide whether to proceed.

Summary

Background and objectives: This prospective, randomized, double-blinded study was designed to compare the effects of desflurane, isoflurane and sevoflurane when combined with remifentanil for induced hypotension on surgical conditions and operative field during tympanoplasty.

Methods: Sixty patients undergoing tympanoplasty were enrolled in the study. The patients were randomized into three groups of 20 each to receive the inhalation anaesthetics desflurane, isoflurane or sevoflurane. Propofol 2 mg kg−1 was administered for induction of anaesthesia in all groups. All patients received a continuous infusion of remifentanil which was titrated between 0.2 and 0.5 μg kg−1 min−1 to achieve a mean blood pressure (BP) of 60–70 mmHg. Nitroglycerine was infused if this BP could not be achieved. Arterial pressures were recorded continuously throughout the operation. Surgical conditions were assessed every 20 min by the blinded surgeon using a six-point category scale (0–5).

Results: One patient in the desflurane group and two patients in isoflurane group required nitroglycerine to maintain desired mean BP. Sustained controlled hypotension was sufficient in all of the groups throughout surgery. Category scale scores were ≤3 throughout the study, except one patient in the sevoflurane group who had a score of 4 at the 60th minute of the operation. No difference was found among groups when haemodynamic parameters and surgical category scale scores were compared. There were no postoperative respiratory and circulatory complications.

Conclusion: Desflurane, sevoflurane or isoflurane combined with remifentanil provided adequate induced hypotension and similar operating conditions and any of them could be safely and equally used in anaesthesia for tympanoplasty.

The effects of acute haemodilution, during prostaglandin E1 (PGE1)-induced hypotension, on the blood coagulation-fibrinolysis system were studied in 40 patients undergoing hip surgery. The patients were randomly divided into four groups of 10 patients each; Group A (control) received no induced hypotension or haemodilution, group B received hypotension alone, group C received haemodilution alone and group D received the combination of induced hypotension and haemodilution. Haemodilution in groups C and D was produced by drawing ≈ 1000 mL of blood and replacing it with the same amount of 6% hydroxyethyl starch. Induced hypotension in groups B and D was conducted with PGE1 and mean blood pressure was maintained at 55 mmHg. The mean dosage of PGE1 was 648 mug in group B and 661 mug in group D. In the control and PGE1-induced hypotension groups there was no significant change in platelet count (PLT), prothrombin time (PT), activated partial thromoplastin time (aPTT), fibrinogen (FIB), antithrombin-III (AT-III) or plasminogen (PLG). Haemodilution alone caused significant decreases in PLT (−43%), PT (+21%), FIB (−33%), AT-III (−21%) and PLG (−27%), and a significant increase in aPTT (+26%), whereas the combination of PGE1-induced hypotension did not cause any further change in these parameters. Serum-fibrin degradation products (FDP) significantly increased (+300%) and PLG significantly decreased (−30%) after surgery in all groups. It can be concluded that acute haemodilution to a haematocrit value of 22 ± 2% causes a slight coagulopathy, which is not enhanced when combined with PGE1-induced hypotension.