Summary

Background and objective: The aim of this prospective, randomized, double-blind investigation was to assess the dose–effect characteristics of postoperative nausea and vomiting after intrathecal administration of small doses of morphine (from 0.015 to 0.25 mg) in opioid-naïve, non-surgical patients. Methods: With Ethic Committee approval and written informed consent 144 opioid-naïve patients suffering from non-cancerous chronic back-pain, and receiving intrathecal morphine as diagnostic test for their chronic pain, were randomly allocated to receive intrathecal injection of 0.015 mg (Group I, n = 25), 0.03 mg (Group II, n = 30), 0.06 mg (Group III, n = 31) or 0.25 mg (Group IV, n = 33) morphine. The control group consisted in 25 further patients not included in the dose–effect study and receiving a placebo injection of normal saline in the interspinous ligament. A blinded observer recorded the occurrence of pruritus, nausea, vomiting, urinary retention and respiratory depression (respiratory rate < 6 bpm) at 2, 4 and 24 h after injection. Results: Clinically significant pain relief was observed in all patients receiving intrathecal morphine but only six patients (25%) of the control group (P = 0.0005). The incidence of pruritus was lower in patients of Groups III (6%) and IV (3%) than in Groups I (12%) and II (20%) (P = 0.002). The incidence of nausea and vomiting was higher at 2- and 4-h observation times, and decreased 24 h after intrathecal injection. Surprisingly, nausea was more frequent in Groups I (56%) and II (50%) than in Groups III (33%) and IV (24%) (P = 0.0005). Vomiting was higher in patients receiving morphine than in control group, but without differences among the four doses. No urinary retention was observed in the control group, while 2 h after intrathecal injection urinary retention was observed in 20–40% of cases, and decreased to less than 10% 24 h after spinal injection without differences among the four doses. Conclusions: The onset and incidence of minor opioid-related side-effects after intrathecal morphine administration do not depend on its dose, occurring with even very small doses of morphine. Accordingly, they can be considered as a patient-dependent effect of the drug, suggesting the presence of a primary dose-independent excitatory component that might be related to the theory of the bimodal activation of opioid receptors. The very low incidence major respiratory depression prevents us from drawing any conclusion about the dose–effect relationship for this side-effect, and further properly powered studies should be advocated to evaluate major respiratory depression after spinal morphine.

Summary

Background and objectives: The aim of this prospective, randomized, double-blind study was to determine the effects of adding two different target-controlled concentrations of remifentanil (1 and 3 ng mL−1) on the desflurane requirement for blunting sympathetic responses after surgical incision (minimum anaesthetic concentration (MACBAR)). Methods: 67 patients, aged 20–50 yr, ASA I, undergoing general anaesthesia for elective abdominal surgery were enrolled and randomly allocated to receive no remifentanil infusion (n = 21) or a target-controlled effect-site concentration of 1 ng mL−1 (n = 24) or 3 ng mL−1 remifentanil (n = 22). All patients were anaesthetized with propofol, cisatracurium and desflurane with a mixture of 60% nitrous oxide in oxygen. Sympathetic responses to surgical incision were determined after a 20-min period of stable end-tidal desflurane and target-controlled remifentanil concentrations. Predetermined end-tidal desflurane concentrations and the MACBAR for each group were determined using an up-and-down sequential-allocation technique. Results: The MACBAR of desflurane was higher in the group receiving no remifentanil (6.25% [95% confidence interval: 5.9–6.5%]) as compared with patients of the groups receiving 1 ng mL−1 (2.7% [2.6–2.8%]; P < 0.001) and 3 ng mL−1 remifentanil (2% [1.9–2.2%]; P < 0.01). When considering a MAC value in this age population and the contribution of 60% nitrous oxide (0.55 MAC), the combined MACBAR values, expressed as multiples of the MAC, were 1.9, 0.8 and 0.6 MAC, in the three groups, respectively. Conclusion: A target-controlled concentration of 1 ng mL−1 remifentanil results in a 57% decrease in the MACBAR of desflurane combined with 60% nitrous oxide. Increasing the target concentration of remifentanil to 3 ng mL−1 produces a further 26% decrease in the MACBAR values of desflurane.

Summary

Background and objectives: Supplemental oxygen is commonly given via nasal cannulae in spontaneously breathing patients. Our modified nasal cannula with a clamp between the nasal prongs can provide O2 via one nostril and CO2 can be sampled through the other one. We have studied whether this cannula can provide oxygenation similar to a standard cannula without affecting end-tidal CO2 monitoring. Methods: Eighty-six patients were studied during spinal anaesthesia and sedation. In 15 patients, arterial blood was sampled while O2 was delivered at flow rates of 0, 2 and 4L min−1, with or without clamping between the prongs of our modified nasal cannula. In the remaining 71 patients, arterial O2 was measured while using our modified nasal cannula with the clamp applied. End-tidal CO2 was recorded on a capnograph and the correlation between end-tidal and arterial values with our modified nasal cannula was investigated. Results: No end-tidal CO2 waveforms were found with oxygen flow greater than 2L min−1 without clamping between the prongs. With clamping there was a significant correlation (r = 0.83) between arterial and end-tidal CO2. A Bland–Altman analysis revealed a bias of 0.49 kPa with precision of ±0.76 kPa. Arterial oxygenation was not affected by our modified nasal prongs with clamp as compared to the standard cannula. Conclusion: Our modified nasal cannula can provide continuous monitoring of end-tidal CO2 without affecting oxygen delivery in sedated, spontaneously breathing patients.

Summary

Background and objective: The cyclic guanosine monophosphate level, which causes an antinociception, is increased in cells as a direct result of phosphodiesterase inhibition. This study used a nociceptive test to examine the nature of the pharmacological interaction between intrathecal zaprinast, a phosphodiesterase inhibitor, and morphine. Methods: Catheters were inserted into the intrathecal space through an incision in the atlantooccipital membrane of male Sprague–Dawley rats. As a nociceptive model, 50 μL of a 5% formalin solution was injected into the hind paw. After observing the effect of zaprinast (37, 111, 369 nmol) and morphine (1, 4, 10, 40 nmol) alone, the interactions of their combination were examined by an isobolographic analysis. Results: Intrathecal zaprinast (P < 0.05) and morphine (P < 0.05) dose-dependently suppressed the flinching observed during phase 1 and phase 2 in the formalin test. The ED50 values (95% confidence intervals) of zaprinast and morphine in phase 1 were 161.9 (87.9–298.3) and 11.6 nmol (4.8–27.9 nmol), respectively. The phase 2 ED50 values (95% confidence intervals) of zaprinast and morphine were 229.9 (142.5–370.9) and 3.9 nmol (1.9–7.6 nmol), respectively. Isobolographic analysis revealed a synergistic interaction after intrathecal delivery a zaprinast–morphine mixture in both phases. The ED50 values of (95% confidence intervals) zaprinast in the combination of zaprinast with morphine in phase 1 and phase 2 were 14.2 (4.9–40.6) and 10.4 nmol (3–35.9 nmol), respectively. Conclusions: Intrathecal zaprinast and morphine are effective against acute pain and facilitated pain state. Zaprinast interacts synergistically with morphine.

Summary

Background and objective: The modified Airway Management Device (AMD) and the Proseal laryngeal mask airway (PLMA) are both supraglottic airway devices designed to maintain airway patency and allow ventilation during anaesthesia. In this prospective, randomized trial, we compared the two devices in patients undergoing major gynaecological procedures. Methods: Eighty-two patients undergoing elective gynaecological surgery were randomized to two groups. Group A (n = 41) had the AMD and Group P (n = 41) the PLMA inserted after induction of anaesthesia. We compared the success of airway placement, time to achieve an airway, oropharyngeal leak pressure and complications associated during anaesthesia. Results: There were no differences in patient characteristic profile for both groups. First time insertion success rates were significantly higher in Group P than in Group A (100% vs. 83%, P < 0.012). Time taken to achieve airway was also significantly shorter in Group P than in Group A (mean 21.9 ± 7.8 s vs. 40.2 ± 48.0 s, P < 0.001). The oropharyngeal leak pressure was significantly higher for Group P than Group A (mean 31.2 ± 5.7 cmH2O vs. 24.2 ± 8.3 cmH2O, P < 0.001). Ten patients in Group A had transient loss of airway during anaesthesia and needed manipulation of the airway device and four patients needed to have the airway switched to PLMA for the rest of the procedure. Conclusions: The modified AMD has a significant lower first time successful placement rate, required a longer insertion time and has a lower oropharyngeal leak pressure than the PLMA. It also demonstrated an increased loss of airway during anaesthesia. The modified AMD needs further evaluation on its efficacy and safety before its further use can be recommended.

Summary

Objective: Intensive insulin therapy reduced mortality in patients admitted to an intensive care unit following mainly cardiac surgery. The aim of this prospective study was to evaluate, if intensive insulin therapy could reduce mortality in medical and non-cardiac surgical patients admitted to a multidisciplinary intensive care unit. Patients and methods: For 6 months all adult patients, admitted to the intensive care unit, were included. Insulin was administered, if blood glucose 12 mmol L−1. For the next 6 months blood glucose level was reduced with intensive insulin therapy (aim 4.4 < BG < 6.1 mmol L−1); 271 patients were included. Patient characteristics data, APACHE II score, morbidity and mortality were recorded. Results: At admission the two groups were comparable. The overall relative mortality was reduced 20% in the intensive insulin treated group (n.s.). In the intensive insulin treated group mortality was 13.1% in the medical patients and 11.2% in the surgical patients compared to 15.8% and 14.4%, respectively, in the conventional treated group (n.s.). The frequency of secondary infections was 21.5% in the intensive insulin treated group and 16.0% in the conventional treated group (n.s.). The proportion of hypoglycaemia increased from 4% to 14% (P < 0.05). Conclusions: Following intensive insulin therapy there was a trend towards reduced mortality in medical and non-cardiac surgical patients but less pronounced as in cardiac surgical patients. Intensive insulin therapy increased the frequency of hypoglycaemia. Around 4400 patients would have to be included in any future randomized study to reach significance.

Summary

Background and objective: We compared the dose requirement and side effect profile of total intravenous anaesthesia using Diprivan® to generic propofol at a specific anaesthetic target level utilizing the bispectral index monitor to determine efficacy differences between the two products. Methods: Sixty women undergoing abdominal hysterectomy were induced with propofol 2 mg kg−1 and maintained with infusion (20–200 μg kg−1 min−1) adjusted to maintain a bispectral index of 50–65. Plasma propofol concentration was measured at 1 and 2 h post induction in 25 patients. Results: Mean (SD) drug doses adjusted for weight and time were similar in the Diprivan® and generic propofol groups: 90 (30) μg kg−1 min−1 vs. 90 (20) μg kg−1 min−1 respectively. Mean (SD) plasma propofol levels at 1 and 2 h were also similar (3.0 (1.0) μg mL−1 vs. 3.6 (1.4) μg mL−1, P = 0.2 and 3.0 (1.9) μg mL−1 vs. 3.4 (1.6) μg mL−1, P = 0.58). Conclusions: Diprivan® and generic propofol have similar efficacy at a specified, bispectral index-defined, depth of anaesthesia.

Summary

Background and objective: Malignant hyperthermia is an inherited disorder of skeletal muscle characterized by muscle contracture and hypermetabolic crisis following exposure to halogenated anaesthetics and depolarizing muscle relaxants. We planned this follow-up to get more information about the safety of non-triggering anaesthesia in susceptible patients; the safety of the use of trigger agents in non-susceptible patients and any minor sequelae following the biopsy. Methods: A questionnaire was sent to 244 patients tested for susceptibility between 1998 and 2004 enquiring about sequelae from the biopsy, subsequent experience with anaesthesia and difficulties encountered because of the investigation. Results: Replies were received from 129 patients. Thirty-four complained about sequelae from the biopsy: 10 reported headache and nausea; 16 experienced pain and a lack of strength in the biopsed leg and 8 found the scar less than satisfactory. Ten patients found it difficult to find a diagnostic centre. Eighteen reported problems and/or delay when they had needed a subsequent anaesthetic. Fourteen patients found the anaesthesiologist reluctant to anaesthetize them and four experienced a delay. Forty-three patients received anaesthesia since their biopsy. Complete medical records were available for 24 anaesthetic exposures in 23 patients. No documented perioperative complications occurred. Only three non-susceptible patients received one trigger agent. Conclusions: It is safe to use trigger-free anaesthesia in susceptible patients. The difficulties encountered by patients to be anaesthetized and the management of the majority of non-susceptible patients during general anaesthesia show the need of more accurate educational programmes and methods for promoting patient-centred care.

Summary

Background and objectives: The GlideScope® is a new video laryngoscope. The aim of our study was to assess its use compared to a Macintosh blade in airway scenarios on the Airman™ airway simulator. The scenarios were: ‘normal’ or resting state of the manikin, pharyngeal obstruction, cervical rigidity and tongue oedema. Methods: Thirty anaesthetists from the Christchurch Anaesthetic Department attempted to pass a bougie or stylet through the vocal cords of the manikin with a size 3 Macintosh blade, then the GlideScope. View at laryngoscopy, ease of ‘intubation’ and whether they thought the GlideScope would be useful in clinical practice were recorded. Results: Forty three percent (P = 0.02) found an improved view with the GlideScope in the pharyngeal obstruction scenario. In the other scenarios there was no significant difference in view. Reportage of ease of intubation showed no statistical difference in any scenarios. However, 93% of anaesthetists considered having the GlideScope would be useful if faced clinically with one or more of the studied scenarios. Conclusions: The GlideScope improved the view in one of three difficult airway situations when used by anaesthetists with no formal training in its use. No single airway device offers a solution to all scenarios, however, we consider that the GlideScope is a useful addition to the range of difficult airway devices available.

Summary

Background and objective: Comparisons between the profile of regional blocks are difficult to make because different methods of testing are used among the studies. The aims of this prospective study were to describe the profile of epidural block by using a scoring system to evaluate the density of the block as assessed by the loss to pinprick, cold and touch sensation; to evaluate the extent of differential block and to determine whether there is any relationship between these three modalities of testing. Methods: We studied 85 parturients undergoing elective Caesarean delivery with epidural anaesthesia with pH adjusted lidocaine 2% with epinephrine 1:400.000 and sufentanil 10 μg. Assessment of sensory block was done in each dermatomal level bilaterally for loss to pinprick, cold and light touch sensation and the density of the block was evaluated on an ordinal scale every 5 min for 20 min and thereafter at 30 and 40 min. Results: We observed a two dermatomes differential block between the complete loss of cold sensation being cephalad and the complete loss of both pinprick and light touch sensation being caudal. We established a significant correlation between the scores used to assess the density of the block in the three different modalities by considering the pinprick score as reference (Spearman's rank correlation is 0.94, P < 0.001 for pinprick vs. cold, 0.97, P < 0.001 for pinprick vs. light touch). Conclusions: By scoring the density of the block on an ordinal scale, knowing the level of the block to pinprick allows one to predict the level of the block to touch and vice versa.

Summary

Background and objective: The GlideScope® videolaryngoscope is a newly developed laryngoscope for tracheal intubation recently introduced into clinical anaesthesia. In this randomised clinical study, we compared the haemodynamic responses to orotracheal intubation using a GlideScope® videolaryngoscope and a fibreoptic bronchoscope. Methods: Fifty-six adult patients, ASA I–II scheduled for elective plastic surgery under general anaesthesia requiring orotracheal intubation were randomly allocated to either the GlideScope® videolaryngoscope group or the fibreoptic bronchoscope group. After a standard intravenous anaesthetic induction, orotracheal intubation was performed. Noninvasive blood pressure and heart rate were recorded before and after induction, at intubation and for 5 min after intubation at 1 min intervals. Results: As compared with the post-induction values the orotracheal intubations using a fibreoptic bronchoscope and a GlideScope® videolaryngoscope resulted in the significant increases in blood pressures which did not exceed their baseline values. In the two groups, heart rates at intubation and within 2 min after intubation were significantly higher than their baseline values. However, there were no significant differences in blood pressures and heart rates at all time points, their maximal values and maximal percent changes during the observation and the times required to reach their maximal values between the two groups. Conclusions: The orotracheal intubations using a fibreoptic bronchoscope and a GlideScope® videolaryngoscope produce similar haemodynamic responses.