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Background Residual neuromuscular block is associated with an increased risk of postoperative pulmonary complications in retrospective studies. The aim of our study was to investigate prospectively the incidence of postoperative pulmonary complications after reversal with either sugammadex (SUG) or neostigmine (NEO) in high-risk older patients. Methods We randomly allocated 180 older patients with significant morbidity (ASA physical status 3) ≥75 yr old to reversal of rocuronium with either SUG or NEO. Adverse events in the recovery room and pulmonary complications (defined by a 5-point [0–4; 0=best to 4=worst] outcome score) on postoperative Days 1, 3, and 7 were compared between groups. Results Data from 168 patients aged 80 (4) yr were analysed; SUG vs NEO resulted in a reduced probability (0.052 vs 0.122) of increased pulmonary outcome score (impaired outcome) on postoperative Day 7, but not on Days 1 and 3. More patients in the NEO group were diagnosed with radiographically confirmed pneumonia (9.6% vs 2.4%; P=0.046). The NEO group showed a non-significant trend towards longer hospital length of stay across all individual centres (combined 9 vs 7.5 days), with a significant difference in Malaysia (6 vs 4 days; P=0.011). Conclusions Reversal of rocuronium neuromuscular block with SUG resulted in a small, but possibly clinically relevant improvement in pulmonary outcome in a select cohort of high-risk older patients. Clinical trial registration ACTRN12614000108617.

Nociception Level Index (NOL) guided analgesia has previously been found to correlate with noxious stimuli during surgery. It was aim of this study to investigate the relationship between intra-operative NOL and acute postoperative pain. After IRB approval, 80 patients scheduled for non-emergency surgery were enrolled. NOL data were recorded from induction of anaesthesia until the end of surgery. After admission to the postoperative acute care unit (PACU), pain scores (numeric rating scale [NRS, 0–10] were obtained 5-minutely for 15 min. NOL data of 74 patients were analyzed. Receiver-operating curve (ROC) analysis identified the NOL reaction to the knife to skin incision (median NOL within 60 s post knife to skin) vs. the median NOL during surgery vs. NOL at the end of surgery to have the highest correlation coefficient (ρ = 0.3; P = 0.01) as well as the highest area under the ROC curve (AUC 0.68; P = 0.01) for the prediction of moderate-severe pain in PACU. A NOL > 20 after skin incision predicted moderate-severe postoperative pain with the highest combined sensitivity (73%) and specificity (58%). A NOL

This review aims to provide an update about the role of deep neuromuscular blockade (NMB) in surgery by providing an overview the literature of the last 3 years. Since the approval of sugammadex for the reversal of deep NMB, the influence of deep NMB on facilitation of surgery as well as postoperative patient outcome has become the focus of increased interest in research. Though deep NMB is still predominantly investigated in the setting of laparoscopic surgery, some recent publications have also investigated deep block in other patient populations. Deep NMB has become increasingly popular and intensely researched. Mounting evidence has documented that surgical conditions are improved when deep (vs. moderate) neuromuscular blockade is used. Though this is true for many, it may not be applicable to all surgical procedures. Previously not well documented, deep vs. moderate NMB may also influence postoperative patient outcome by a reduction in surgical complication rates and/or decreased postoperative pain after certain procedures.

Background The QNox score (Quantium Medical S.L., distributed by Fresenius Kabi) has recently been introduced as a tool to quantify intraoperative analgesia. Being based on the analysis of electroencephalographic data, QNox is distinctly different to other methods of nociception monitoring that rely almost entirely on the assessment of sympathetic activity. However, there are currently no published data to validate use of QNox in a clinical setting. We investigated the value of pre-arousal QNox data at the end of surgery for prediction of acute postoperative pain in the PACU. Methods A total of 150 patients scheduled for non-emergency surgery under sevoflurane-opioid general anaesthesia were included in the study. At the end of surgery but before patient arousal, QNox was measured minutely for 5 min. After admission to the recovery room, pain scores (numeric rating scale [NRS], 0–10) were obtained 5 minutely for 15 min. Results Data from 144 patients were analysed. QNox before arousal showed no correlation (ρ=0.057) with acute postoperative pain in the PACU. Furthermore, the score was found to have no value for the prediction of acute postoperative pain (area under the receiver operating curve, 0.501; 95% confidence interval, 0.406–0.597). Conclusion QNox at the end of surgery before arousal showed no association with and allowed no prediction of acute pain in the PACU. Clinical trial registration ACTRN12618001662257.

Nociception Level Index (NOL) guided analgesia has previously been found to correlate with noxious stimuli during surgery. It was aim of this study to investigate the relationship between intra-operative NOL and acute postoperative pain. After IRB approval, 80 patients scheduled for non-emergency surgery were enrolled. NOL data were recorded from induction of anaesthesia until the end of surgery. After admission to the postoperative acute care unit (PACU), pain scores (numeric rating scale [NRS, 0-10] were obtained 5-minutely for 15 min. NOL data of 74 patients were analyzed. Receiver-operating curve (ROC) analysis identified the NOL reaction to the knife to skin incision (median NOL within 60 s post knife to skin) vs. the median NOL during surgery vs. NOL at the end of surgery to have the highest correlation coefficient (ρ = 0.3; P = 0.01) as well as the highest area under the ROC curve (AUC 0.68; P = 0.01) for the prediction of moderate-severe pain in PACU. A NOL 20 after skin incision predicted moderate-severe postoperative pain with the highest combined sensitivity (73%) and specificity (58%). A NOL 10 after skin incision excluded moderate-severe pain in PACU with a negative predictive value of 83%. The NOL reaction to skin incision, but not NOL during surgery appears to allow the exclusion and, to a lesser degree the prediction of moderate-severe pain in PACU. The results may also strengthen the manufacturers recommendation of an intraoperative NOL range of 10-25.Australian New Zealand Clinical Trials Registry: ACTRN12619001596190.

Pudendal nerve injuries are not an uncommon side effect of patient positioning on a traction table, and muscle relaxation has been suggested to mitigate this risk by reducing pressure on the perineum. A total of 40 patients scheduled for hip arthroscopic surgery under general anaesthesia were recruited. After induction of anaesthesia, pressures on the perineum were measured in 20 subjects by means of an ultra-thin pressure sensor mat wrapped around the perineal post. Perineal pressures were assessed after the induction of anaesthesia, after leg traction and after deep muscle relaxation. In 22 subjects, the hip joint width was measured radiographically at the same time points. Pressures on the perineum were high after traction (median maximum pressure 2540 g cm−2). Neuromuscular paralysis reduced perineal pressures only minimally, but significantly (−5 g cm−2; P = 0.007). Traction increased hip joint width significantly [mean 66 (12)%; P = 0.001) and muscle relaxation further increased joint width by a mean of 3.2 (0–20)% (P = 0.001). Muscle relaxation was more beneficial for male patients (joint width increase 6.8% versus 2.8%; P = 0.04), as well as patients in whom traction alone did not achieve sufficient joint width. Muscle relaxation reduced the perineal pressure during hip arthroscopic surgery by only a negligible amount. With regard to joint space, relaxation may be of highest benefit in male patients and/or patients in whom traction alone produces only a relatively small increase in joint width (trial registration: ANZCTR 12617000191392).

Against the background of increasing healthcare costs and diminishing budgets, this review aims to present clinicians with ethically viable options to overcome budgetary restraints when seeking to introduce novel products.Healthcare administrators and primary healthcare providers are not unlikely to have different opinions when discussing the introduction of novel products. However, rather than taking a 'no' for an answer, doctors may be able to argue for a change - even if this may seem to come at a higher cost. The recent introduction of the reversal agent sugammadex may provide a timely example for the possibility of success 'against all financial odds'.Health professionals have the responsibility to deliver high-quality care while acknowledging the financial budget constraints. However, evidence (vs. perception) for outcome benefits of novel drugs or devices should stimulate a robust desire for their timely introduction. Demonstrating actual benefits understandable to administrators, seeking alliances with other medical specialties or patient groups, as well as negotiations with the healthcare industry may all represent viable options. Simply waiting for patents to expire should remain a measure of last resort.

Nociception, in contrast to pain, is not a subjective feeling, but the physiological encoding and processing of nociceptive stimuli. However, monitoring nociception remains a challenge in attempts to lower the incidence of acute postoperative pain and the move towards a more automated approach to analgesia and anaesthesia. To date, several commercialised devices promise a more accurate reflection of nociception than the traditionally used vital signs, blood pressure and heart rate. This narrative review presents an overview of existing technologies and commercially available devices, and offers a perspective for future research. Although firm conclusions about individual methods may be premature, none currently appears to offer a sufficiently broad applicability. Furthermore, there is currently no firm evidence for any clinically relevant influence of such devices on patient outcome. However, the available monitors have significantly aided the understanding of underlying mechanisms and identification of potential pitfalls.

Background Reported outcome benefits after surgical pleth index (SPI, GE Healthcare, Helsinki, Finland) guided anaesthesia are conflicting. One potential explanation may be the lack of evidence for the selection of meaningful SPI target values. A recently published trial found an SPI cut-off of 30 as a ‘best-fit' to predict moderate-to-severe acute postoperative pain. This prospective trial was designed to validate this target and to investigate the influence of patient age on SPI in this context. Methods After ethics approval, 200 patients undergoing non-emergency surgery were enrolled. Data related to SPI, heart rate (HR), and mean arterial pressure (MAP) were recorded for the last 5 min of surgery, just before arousal. After admission to recovery, pain scores (numeric rating scale [NRS], 0–10) were obtained every 5 min for 15 min. Results The data of 196 patients were analysed. Receiver-operating curve analysis showed a cut-off SPI value of 29 to be the optimum intraoperative target to discriminate between NRS 0–3 and 4–10. This confirms the ‘best fit' cut-off for SPI published previously. Though still superior to HR and MAP, the sensitivity and specificity of the SPI were only poor. Age had no influence on the predictive accuracy of SPI. Conclusions An SPI of approximately 30 was confirmed as having the best sensitivity/specificity to predict moderate-to-severe pain in the postanaesthesia care unit. However, the predictive accuracy was overall poor and not influenced by patient age. Clinical trial registration ACTRN12617001475336.

Background Laparoscopic surgery causes specific post-operative discomfort and intraoperative cardiovascular, pulmonary, and splanchnic changes. The CO2 pneumoperitoneum-related intra-abdominal pressure (IAP) remains one of the main drivers of these changes. We investigated the influence of deep neuromuscular blockade (NMB) on IAP and surgical conditions. Methods This is an open prospective single-subject design study in 20 patients (14 female/6 male) undergoing laparoscopic cholecystectomy. Inclusion criteria were 18 years or older, and American Society of Anesthesiologists classification 1 to 3. Under a standardised anaesthesia, lowest IAP providing adequate surgical conditions was assessed without NMB and with deep NMB [post-tetanic count (PTC)

Background Total oxygen consumption has been found to be reduced under deep neuromuscular blockade due to a lower rate of metabolism of skeletal muscles. However, the magnitude of this effect in individual muscles has not been investigated. Thus the aim of this study was to compare the oxygenation of paralyzed versus non-paralyzed forearm muscle under tourniquet-provoked ischemia. Methods After ethics approval and written informed consent, 30 patients scheduled for elective hand and wrist surgery were included. Ischemia was provoked by inflation of bilateral upper arm tourniquets and muscle relaxation was achieved via intravenous administration of rocuronium 0.9 mg/kg. Bilateral tourniquets were applied to both upper arms before induction of anesthesia and near infrared spectrometry (NIRS) electrodes applied on both forearms. Muscular ischemia in an isolated (= non-paralyzed, NP) as well as a paralyzed forearm (P) was created by sequential inflation of both tourniquets before and after intravenous administration of rocuronium. Muscle oxygen saturations (SmO2) of NIRS in both forearms and their changes were determined and compared. Results Data of 30 patients (15 male, 15 female; 41.8 ± 14.7 years) were analyzed. The speed of SmO2 decrease (50% decrease of SmO2 from baseline (median [percentiles]: NP 210 s [180/480s] vs. P 180 [180/300]) as well as the maximum decrease in SmO2 (minimum SmO2 in % (median [percentiles]: NP 20 [19/24] vs. P 21 [19/28]) were not significantly affected by neuromuscular paralysis. Conclusions No significant effect of muscle relaxation on NIRS-assessed muscle oxygenation under tourniquet-induced ischemia was found in human forearm muscles.

Purpose. Residual neuromuscular blockade (RNMB) is known to be a significant but frequently overlooked complication after the use of neuromuscular blocking agents (NMBA). Aim of this prospective audit was to investigate the incidence and severity of RNMB at our Australian tertiary pediatric center.Methods. All children receiving NMBA during anesthesia were included over a 5-week period at the end of 2011 (Mondays to Fridays; 8 a.m.–6 p.m.). At the end of surgery, directly prior to tracheal extubation, the train-of-four (TOF) ratio was assessed quantitatively. Data related to patient postoperative outcome was collected in the postoperative acute care unit.Results. Data of 64 patients were analyzed. Neostigmine was given in 34 cases and sugammadex in 1 patient. The incidence of RNMB was 28.1% overall (without reversal: 19.4%; after neostigmine: 37.5%; n.s.). Severe RNMB (TOF ratio < 0.7) was found in 6.5% after both no reversal and neostigmine, respectively. Complications in the postoperative acute care unit were infrequent, with no differences between reversal and no reversal groups.Conclusions. In this audit, RNMB was frequently observed, particularly in cases where patients were reversed with neostigmine. These findings underline the well-known problems associated with the use of NMBA that are not fully reversed.

Since its launch in 2008, sugammadex has been considered one of the most significant developments in anaesthesia-related pharmacology. With almost 500 sugammadex-related publications and over nine million patient exposures worldwide, user experience and scientific data have grown exponentially. However, several important questions are yet to be answered. This article reviews the sugammadex-related literature in 2013 and 2014 to determine which of these questions have been answered more fully over the last 18 months and which questions require more information and research.

Cuffed tracheal tubes are increasingly used in paediatric anaesthetic practice. This study compared tidal volume and leakage around cuffed and uncuffed tracheal tubes in children who required standardised mechanical ventilation of their lungs in the operating theatre. Children (0-16 years) undergoing elective surgery requiring tracheal intubation were randomly assigned to receive either a cuffed or an uncuffed tracheal tube. Assessments were made at five different time-points: during volume-controlled ventilation 6 ml.kg-1 , PEEP 5 cmH2 O and during pressure-controlled ventilation 10 cmH2 O / PEEP 5 cmH2 O. The pressure-controlled ventilation measurement time-points were: just before a standardised recruitment manoeuvre; just after recruitment manoeuvre; 10 min; and 30 min after the recruitment manoeuvre. Problems and complications were recorded. During volume-controlled ventilation, leakage was significantly less with cuffed tracheal tubes than with uncuffed tracheal tubes; in ml.kg-1 , median (IQR [range]) 0.20 (0.13-0.39 [0.04-0.60]) vs. 0.82 (0.58-1.38 [0.24-4.85]), respectively, p < 0.001. With pressure-controlled ventilation, leakage was less with cuffed tracheal tubes and stayed unchanged over a 30-min period, whereas with uncuffed tracheal tubes, leakage was higher and increased further over the 30-min period. Tidal volumes were higher in the cuffed group and increased over time, but in the uncuffed group were lower and decreased over time. Both groups showed an increase in tidal volumes following recruitment manoeuvres. There were more short-term complications with uncuffed tracheal tubes, but no major complications were recorded in either group at long-term follow-up. With standardised ventilator settings, cuffed tracheal tubes produced better ventilation characteristics compared with uncuffed tracheal tubes during general anaesthesia for routine elective surgery.

Background . Surgical Pleth Index (SPI) is a non-invasive, dimensionless score (0–100) aimed to allow an estimate of intraoperative nociception. Thus, it may be a useful tool to guide intraoperative analgesia. However, no optimum SPI target range for the use in children has yet been defined. It was the aim of this study to define a clinically appropriate SPI target to predict moderate-severe postoperative pain in children. Methods . After ethics approval 105 children (2–16 yr) undergoing elective sevoflurane/opioid-based anaesthesia were included. SPI was recorded directly before the end of surgery and compared with acute postoperative pain (age appropriately assessed on different pain scales in the age groups two to three yr, four to eight yr and nine to16 yr) in the postoperative acute care unit (PACU). Results . Data of 93 children were analysed. A significant negative correlation was found between age and SPI (r=−0.43; P=0.03). The SPI cut-off value with the highest sensitivity (76%) and specificity (62%) in all children combined was 40. The negative predictive value for SPI ≤ 40 to predict the absence of moderate-severe pain in PACU was 87.5%. The commonly used SPI cut-off (50) published in all related studies had neither any clinically relevant sensitivity nor specificity to predict the presence or absence of acute pain in PACU. Conclusions The results suggest that a lower (≤ 40) than previously published (50) target for SPI may be more appropriate in studies investigating SPI guided anaesthesia in children, if the avoidance of moderate-severe postoperative pain is the main goal. Clinical trial registration ACTRN12616001139460.

Background The use of neuromuscular blocking agents has previously been suggested to facilitate the dissection of the latissimus dorsi muscle during breast reconstructive surgery. The aim of this study was to quantify the influence of deep muscle relaxation on the force required to lift the latissimus dorsi muscle during flap preparation. Methods After ethics approval and written informed consent 15 patients scheduled for elective breast reconstruction with a latissimus dorsi pedicled flap (muscle flap, not myocutaneous flap) under general anaesthesia were prospectively included. Midway through the muscle dissection a sterile cotton tape was slung around the mid portion of the muscle and connected with a sterile strain gauge stably positioned just above the patient. Thereafter, the muscle was lifted by moving the strain gauge vertically upwards until a muscle tension similar to that created manually during muscle dissection was achieved. The force (N) and distance required to tension the muscle were recorded and the tension released. In a randomized and blinded crossover design either rocuronium (0.6 mg.kg-1) or normal saline were given intravenously, and the tension protocol was repeated 2 min after each drug administration. Results Muscle relaxation significantly reduced the force for flap tensioning (median [percentiles] – 22 [-32/-13] %; P = 0.011) in 10/15 patients. However, in the remaining 5 patients no significant effect was measured. Normal saline had no effect on the measured force. Conclusions Deep muscle relaxation significantly reduces the force required to manually elevate the latissimus dorsi muscle during its dissection in the majority of but not all patients. Trial registration The study was retrospectively registered on [17.6.2014] with the Australian and New Zealand Clinical Trials Registry. ACTRN12614000637640

Postoperative residual neuromuscular blockade (RNMB) is associated with significant morbidity.The aim of this retrospective data analysis was to investigate the influence of the method of RNMB reversal on postoperative outcome.Tertiary teaching hospital in Western Australia.With Ethics Committee approval, data from 1444 patients who received at least one dose of a non-depolarising muscle relaxant intraoperatively during 2011 were analysed.Endpoints included unwanted events in the postanaesthesia care unit (PACU); symptoms of pulmonary complications within 7 postoperative days (0 to 100 outcome score based on 'temperature38°C', 'leucocyte count11 × 10 l', 'physical examination consistent with pneumonia' and 'shortness of breath'); PACU turnover time; and length of hospital stay.Data from 1444 patients (722 sugammadex, 212 neostigmine and 510 no-reversal) were analysed. The incidence of postoperative nausea and vomiting (PONV) in PACU was higher in neostigmine-reversed than sugammadex-reversed patients (21.5 vs. 13.6%; P 0.05). No differences were found regarding other PACU incidents, length of PACU stay or hospital stay. Pulmonary outcome deteriorated significantly (outcome score increased) with age and American Society of Anesthesiologists (ASA) physical status. This was observed particularly in ASA 3/4 patients more than 60 years of age in neostigmine-reversed or non-reversed patients, but almost no detrimental effect of age on pulmonary outcome was found in the sugammadex group (P 0.05).RNMB reversal with sugammadex was associated with the lowest rate of PONV and may reduce the risk of pulmonary complications in elderly ASA 3/4 patients.Australian New Zealand Clinical Trials Registry: ACTRN12612000087853.

The vasodilation accompanying acute alcohol ingestion is hard to reconcile with the strong evidence linking chronic alcohol consumption with hypertension. Cytochrome P450 (CYP450) eicosanoids derived from arachidonic acid include vasodilator epoxyeicosatrienoic acids (EETs) and the vasoconstrictor 20-hydroxyeicosatrienoic acid (20-HETE). This study aimed to examine the relationship between CYP450 eicosanoids and blood pressure (BP), and compared the effect of single session of drinking red wine with de-alcoholized red wine (DRW) or water over 24 h.Twenty-five normotensive men were randomly assigned to drink either 375 ml of red wine (41 g of alcohol) or the equivalent volume of DRW or water, with a light meal on 3 separate days. Ambulatory BP and heart rate were measured over 24 h. Blood samples were obtained before and 2, 4 and 24 h after beverage consumption.Blood pressure fell in the first 4 h after red wine consumption (P = 0.001), but was significantly higher after 20 h (P = 0.037). Plasma 20-HETE fell in the 2 h after consumption of all beverages, but over the 24-h period was relatively higher after red wine consumption (P = 0.025). The largest difference in 20-HETE was 2 h after consuming red wine and coincided with the highest blood alcohol level. There were no significant effects of red wine on plasma EETs.Acute consumption of alcohol as red wine results in a relative increase in plasma levels of the vasoconstrictor 20-HETE over 24 h without affecting EETs, and may contribute to the BP elevation that associates with a binge drinking pattern or be a homeostatic response to the acute fall in BP induced by alcohol.

Background The Analgesia Nociception Index has been described to reflect different levels of intraoperative nociceptive stimulation during total intravenous anaesthesia. The association between this index and haemodynamic changes during sevoflurane-based anaesthesia was investigated in 30 patients with the hypothesis that changes in the Analgesia Nociception Index may coincide with or even predict haemodynamic changes. Methods The Analgesia Nociception Index as well as blood pressure and heart rate were observed during induction, at skin incision, at times of an Analgesia Noceception Index decrease > 20% (‘event’) and pre-/post-fentanyl administration. Results The Analgesia Nociception Index decreased with airway manipulation [mean: 52 (before) vs. 33 (after); P 10% was low (heart rate 0.61; blood pressure 0.59). Conclusions The Analgesia Nociception Index appears to reflect different levels of stimulation during sevoflurane-based general anaesthesia. However, it was of little predictive value to pre-empt significant haemodynamic changes.

Background: The aim of this prospective audit was to investigate clinical practice related to muscle relaxant reversal and the impact made by the recent introduction of sugammadex on patient outcome at a tertiary teaching hospital. Methods: Data from all patients intubated at our institution during two epochs of seven consecutive days each was collected prospectively. Directly prior to extubation, the train-of-four (TOF) ratio was assessed quantitatively by an independent observer. Postoperative outcome parameters were complications in the recovery room and radiological diagnosed atelectasis or pneumonia within 30 days. Results: Data from 146 patients were analysed. Three reversal strategies were used: no reversal, neostigmine or sugammadex. The TOF ratio was less than 0.7 in 17 patients (nine no reversal, eight neostigmine) and less than 0.9 in 47 patients (24 no reversal, 19 neostigmine, four sugammadex). Those reversed with sugammadex showed fewer episodes of postoperative oxygen desaturation (15% vs. 33%; P

There are conflicting reports concerning the outcome after anaesthesia guided by the surgical pleth index (SPI; GE Healthcare, Helsinki, Finland). One potential explanation may be the lack of evidence for the selection of SPI cut-off values. The aim of this trial was to investigate the correlation between SPI, arousal, and postoperative pain and to define a cut-off value for SPI to predict moderate-to-severe pain.After obtaining ethical approval and written informed consent, 70 patients undergoing non-emergency surgery were enrolled. Data relating to SPI, heart rate, mean arterial pressure, and state entropy were recorded every 10 s for the last 10 min of surgery (state entropy60 at all times). Subsequently, recordings continued during the phase of arousal. After recovery room admission, pain scores (numerical rating scale 0-10) were obtained every 3 min for 15 min.Data from 65 patients were analysed. Receiver-operating characteristic curve analysis revealed an optimal intraoperative cut-off SPI value of 30 to discriminate between numerical rating scale scores 0-3 and 4-10. For this value, the negative and positive predictive values to discriminate between numerical rating scale scores 0-3 and 4-10 were 50 and 89.7%, respectively. The SPI was significantly affected by arousal, and SPI scores obtained during this phase were not predictive of postoperative pain.Surgical pleth index values are predictive of postoperative pain only if obtained before patient arousal. In contrast to previous studies, a relatively low SPI, 30, appears to predict pain with a high positive predictive value and may therefore be suggested for future studies of SPI-guided anaesthesia.Australian New Zealand Clinical Trials Registry: ACTRN12615000804583.

Introduction. This survey aimed to investigate the attitudes/practice pertaining the use, management, and monitoring of neuromuscular blockade amongst Singaporean anaesthetists.Methods. All specialist accredited anaesthetists registered with the Singapore Medical Council were invited to complete an anonymous online survey.Results. The response rate was 39.5%. Neuromuscular monitoring (NM) was used routinely by only 13.1% despite the widespread availability of monitors. 82% stated residual NMB (RNMB) was a significant risk factor for patient outcome, but only 24% believed NMB monitoring should be compulsory in all paralyzed patients. 63.6% of anaesthetists estimated the risk of RNMB in their own institutions to be 50% said such benefits may be able to offset the associated costs.Conclusions. There is a significant need for reeducation about RNMB, studies on local RNMB incidences, and strengthening of current monitoring practices and guidelines. Strategies are discussed. As NM monitors appear widely available and reversal of NMB standard practice, it is hopeful that Singaporean anaesthetists will change and strive for evidence-based best clinical practice to enhance patient safety.

Sugammadex is known to rapidly and completely reverse the effects of amino-steroidal neuromuscular blocking agents. However, the high costs of sugammadex have so far prevented its introduction as the standard reversal agent in most healthcare systems. At the Royal Perth Hospital, sugammadex was recently introduced as an unrestricted alternative to neostigmine for the reversal of amino-steroidal neuromuscular blocking agents. The aim of this retrospective observational audit was to investigate the impact of this change on clinical practice and associated healthcare costs. Data from all patients intubated during a one-month period in April to May 2010 and for a similar period in 2011 were retrospectively collected and the use of neuromuscular blocking agents and reversal agents were identified and the associated costs were calculated. More steroidal neuromuscular blocking agents and sugammadex (+743%), but less glycopyrrolate and neostigmine (-48%) were used in 2011. Using the manufacturer's list price, muscle relaxation and reversal costs increased from about A$42 per case to about A$127 per case. Between the investigated time periods no differences were found for anaesthesia time, operating time or time spent in the post anaesthesia care unit. However, there was a statistically significant decrease in the time between surgery and discharge (median 2.0 vs 2.2 days). While the design of the audit was such that no inferences can be made about the cause of this change, this is an interesting observation worthy of further investigation.

'Surgical Stress Index' and the 'Number of Fluctuations in Skin Conductance.s⁻¹, use different methods to analyse sympathetic tone and so provide an estimate of peri-operative analgesia. The aim of our study was to investigate the relationship between these methods and stress hormone plasma levels. In 20 patients scheduled for elective surgery, values of the two methods, mean arterial blood pressure, heart rate and blood samples (to measure plasma levels of adrenaline, noradrenaline, adrenocorticotrophic hormone and cortisol) were obtained at five time points. Changes in Surgical Stress Index and the Number of Fluctuations in Skin Conductance.s⁻¹ only partially reflected changes in plasma noradrenaline levels. Surgical Stress Index, heart rate and blood pressure, but not the 'Number of Fluctuations in Skin Conductance.s⁻¹ changed in response to changes in depth of analgesia by showing significant differences between before and after a bolus of fentanyl. However, the overall predictive ability of both methods was poor.

Background Monitoring changes in electrical skin conductance has been described as a potentially useful tool for the detection of acute pain in adults. The aim of this study was to test the method in pediatric patients. Methods A total of 180 postoperative pediatric patients aged 1-16 yr were included in this prospective, blinded observational study. After arrival in the recovery unit, pain was assessed by standard clinical pain assessment tools (1-3 yr: Face Legs Activity Cry Consolability Scale, 4-7 yr: Revised Faces Scale, 8-16 yr: Visual Analogue Scale) at various time points during their stay in the recovery room. The number of fluctuations in skin conductance per second (NFSC) was recorded simultaneously. Results Data from 165 children were used for statistical analysis, and 15 patients were excluded. The area under the Receiver Operating Characteristic curve for predicting moderate to severe pain from NFSC was 0.82 (95% confidence interval 0.79-0.85). Over all age groups, an NFSC cutoff value of 0.13 was found to distinguish between no or mild versus moderate or severe pain with a sensitivity of 90% and a specificity of 64% (positive predictive value 35%, negative predictive value 97%). Conclusions NFSC accurately predicted the absence of moderate to severe pain in postoperative pediatric patients. The measurement of NFSC may therefore provide an additional tool for pain assessment in this group of patients. However, more research is needed to prospectively investigate the observations made in this study and to determine the clinical applicability of the method.

BACKGROUND AND OBJECTIVE: An estimated 150 million people worldwide use cannabis. The effect of cannabis on anaesthetic requirements in humans does not appear to have been studied. METHODS: In this prospective, randomized, single-blinded study, 30 male patients using cannabis more than once per week (group C) and 30 nonusers (group NC), aged 18-50 years, were induced with propofol 1.5, 2, 2.5, 3 or 3.5 mg kg. Additional doses were given when required. The primary outcome was the 50% effective dose of propofol and successful induction was determined by loss of consciousness with a bispectral index value of less than 60 and satisfactory insertion of a laryngeal mask. Propofol requirements to achieve these outcomes were recorded. RESULTS: The dose required to achieve the target bispectral index value was not significantly higher in group C, but group C required a significantly higher propofol dose to achieve laryngeal mask insertion (314.0 +/- 109.3 vs. 263.2 +/- 69.5 mg, P < 0.04). The estimated effective propofol induction dose in 50-95% of patients did not significantly differ between groups. CONCLUSION: We conclude that cannabis use increases the propofol dose required for satisfactory clinical induction when inserting a laryngeal mask. (Less)

Background and objective: Hypotension following spinal anaesthesia (SA) is common, especially in the elderly. Elevated sympathetic tone has been shown to correlate with severe hypotension after SA. The aim of this prospective trial was to investigate skin conductance (SC), as a measure of sympathetic tone, to predict hypotension after SA. Methods: After ethical approval and written informed consent, 30 patients undergoing SA were included. Baseline measurements of SC [number of fluctuations per second (reflecting the firing rate of skin sympathetic nerves), area under the curve (AUC) A and B (reflecting the magnitude of the sympathetic impulse)], blood pressure and heart rate were recorded. After administration of SA, all parameters were assessed every 2.5 min for a total of 15 min. Baseline readings of SC were compared with the lowest blood pressure within the study period. Results: Data from 30 subjects [73 (8) years] were analysed. After SA, the mean arterial blood pressure declined an average of 21.3 (11.3) mmHg. A cut-off value of 0.35 μSs for baseline AUC B allowed prediction of more than mild hypotension (>15% from baseline) after SA with a sensitivity of 72.5% and a specificity of 77.5%. Conclusions: AUC B, as a parameter of SC, may predict severe arterial hypotension after SA in the elderly.

Background and objective: Sevoflurane has been shown to distinctly reduce bronchial mucus transport velocity, an essential determinant of mucociliary clearance and pulmonary complications. However, sevoflurane is regarded as one of the least irritant volatile anaesthetics, especially when compared with desflurane. Hence, the aim of this double-blind, randomized, controlled trial was to assess differences in bronchial mucus transport velocity between sevoflurane and desflurane. Methods: Twenty patients listed for general surgery were randomized to receive either maintenance of anaesthesia with desflurane and fentanyl, or sevoflurane and fentanyl. Thirty minutes after tracheal intubation, bronchial mucus transport velocity was assessed by fibreoptic observation of the movement of methylene blue dye applied to the dorsal surface of the right main bronchus. Results: Both agents distinctly reduced bronchial mucus transport velocity when compared with previous studies, but the degree of impairment did not significantly differ between the investigated groups (median [25%/75% percentile]): desflurane 1.5 [0.5/4.2] vs. sevoflurane 1.3 [0.3/2.9] mm min -1 , P = 0.343). Conclusions: Desflurane is commonly regarded as more irritant to the airway, but as far as bronchial mucus transport velocity is concerned, the choice between sevoflurane and desflurane does not seem to matter.

To investigate if changes in low-to-high frequency ratio (LF/HF), low frequency (LF) and high frequency (HF) heart rate variability reflect autonomic regulation during spinal anaesthesia (SA) in pregnant women scheduled for elective Caesarean section.Prospective clinical trial. Systolic blood pressure (SBP) and heart rate variability were analysed at baseline, 5 min after SA and 15 min after SA. Patients were assigned by baseline LF/HF. Group LF/HF2.5 (n= 52) was compared to group LF/HF2.5 (n= 48). Non-parametric tests for statistical analysis.Group LF/HF2.5 showed a significant decrease in LF/HF and LF as well as an increase in HF during SA (median, range): baseline LF/HF [4.0 (3.2/4.8)] decreased to 2.3 (1.3/3.4) at event 15 min after SA (P0.001). Baseline LF = 59(43/71)% decreased to 40 (27/55)% at event 15 min after SA (P0.05). Baseline HF = 15(13/22)% increased to 26(15/41)% at event 15 min after SA (P0.05). In contrast, group LF/HF2.5 demonstrated only moderate changes in LF/HF, LF and HF during SA. SBP decreased significantly in group LF/HF2.5 (median and range) lowest SBP group LF/HF2.5: 80 (50/127 mmHg vs. group LF/HF2.5: 109 (104/142) mmHg, P0.001. Decrease of SBP before and after SA was correlated with a decrease in LF/HF, LF, and HF, respectively: LF/HF - SBP: r= 0.30, r(2)= 0.09, P0.001; LF - SBP: r= 0.25, r(2)= 0.06, P0.05, HF, NS.Changes in heart rate variability parameters in the course of SA may reflect a decrease in sympathetic activity and relative increase in parasympathetic activity as a result of the block. In the course of SA, the more pronounced the changes in heart rate variability were the more distinct the hypotension.

Background Arousal after total i.v. anaesthesia (TIVA) has been reported to be detectable by monitoring the number of fluctuations per second (NFSC), a parameter of skin conductance (SC). However, compared with monitoring of the bispectral index (BIS ® ), the predictive probability of NFSC was significantly lower. The aim of this study was to determine the value of the two new, not yet published parameters of SC, area under the curve (AUC) methods A and B, for monitoring emergence from TIVA compared with monitoring of NFSC and BIS ® . Methods Twenty-five patients undergoing surgery were investigated. NFSC, AUC A, AUC B, BIS ® , and haemodynamic parameters (mean arterial pressure and heart rate) were recorded simultaneously. The performance of the monitoring devices in distinguishing between the clinical states ‘steady-state anaesthesia', ‘first clinical reaction', and ‘extubation' were compared using the method of prediction probability (Pk) calculation. Results BIS ® showed the best performance in distinguishing between ‘steady-state anaesthesia' vs ‘first reaction' (Pk BIS ® 0.95; NFSC 0.73; AUC A 0.54; AUC B 0.62) and ‘steady-state anaesthesia' vs ‘extubation' (Pk BIS ® 0.99; NFSC 0.73; AUC A 0.71; AUC B 0.67). However, the time from first BIS ® >60/SC>0 to a first clinical reaction was significantly shorter for BIS ® (median BIS ® 180 s; NFSC 780 s; AUC A 750 s; AUC B 690 s; P Conclusions AUC A and AUC B did not improve accuracy of SC monitoring in patients waking after TIVA.

Many studies comparing the i-gel(™) with laryngeal masks include patients in whom laryngeal mask cuff inflation pressures are higher than recommended, or involve the use of neuromuscular blocking drugs and positive pressure ventilation. We compared the i-gel with the PRO-Breathe(®) laryngeal mask in anaesthetised, spontaneously breathing children. Two hundred patients aged up to 16 years were randomly allocated to either the i-gel or the PRO-Breathe laryngeal mask. The PRO-Breathe was inflated to an intracuff pressure of 40 cmH2 O. All patients received pressure support of 10 cmH2 O and positive end-expiratory pressure of 5 cmH2 O. Successful insertion at the first attempt was 82% for the i-gel compared with 93% for the PRO-Breathe (p = 0.019). Leakage volume was significantly higher with i-gel sizes 1.5 (p = 0.015), 2 (p = 0.375), 2.5 (p = 0.021) and 3 (p = 0.003) compared with the equivalent-sized PRO-Breathe device. Device dislodgement following successful initial placement was more frequent with the i-gel (5%) compared with the PRO-Breathe laryngeal mask (0%). We conclude that the PRO-Breathe laryngeal mask is superior to the i-gel in terms of leakage volume and device dislodgement.

When neuromuscular blocking agents (NMBA) were introduced into clinical practice in 1942, the event was called the "second revolution in anesthesia." Despite some significant side effects, NMBAs have remained in the anesthetists' repertoire, not at least because muscle relaxation has been claimed to allow or facilitate many surgical procedures. Aim of this literature review was to investigate the evidence for the use of NMBA as well as the optimum depth of neuromuscular blockade during laparoscopic surgery. Muscle relaxation may optimize laparoscopic operating conditions by preventing patient movement and achieving more intra-abdominal space for a given intra-abdominal insufflation pressure. In this context, deeper than normally maintained levels of neuromuscular blockade appear to be superior. However, the decision to utilize deeper than standard muscle relaxation should currently be based on a risk-benefit analysis for each individual patient. Thus good communication between surgeon and anesthetist remains crucial to achieve best outcomes.

Sugammadex was introduced to Royal Perth Hospital in early 2011 without access restriction. Two departmental audits (26-page online survey and 1-week in-theatre snapshot audit) were undertaken to investigate the change of beliefs and clinical practice related to the use of neuromuscular blocking agents at the Royal Perth Hospital since this introduction. Results were compared with data from 2011. We found that, in the 2.5 years since introduction of Sugammadex, more anesthetists (69.5 versus 38%) utilized neuromuscular monitoring, and aminosteroidal neuromuscular blocking agents were used in 94.3% of cases (versus 77% in 2011). Furthermore, 53% of anesthetists identified with a practice of “deeper and longer” intraoperative paralysis of patients. All 71 patients observed during the 5-day in-theatre audit were reversed with Sugammadex. Since the introduction of Sugammadex, 69%(n=20)of respondents felt it provided “faster turnover,” less postoperative residual neuromuscular blockade(n=23; 79%), and higher anesthetist satisfaction(n=17; 59%). 45%(n=13)of colleagues reported that they would feel professionally impaired without the unrestricted availability of Sugammadex, and 1 colleague would refuse to work in a hospital without this drug being freely available. In clinical practice Sugammadex was frequently (57%) mildly overdosed, with 200 mg being the most commonly administered dose.

Background. Changes in skin conductance have previously been reported to correlate well with plasma levels of stress hormones and awakening stimuli. In this study, monitoring of skin conductance during emergence from general anaesthesia was compared with the monitoring of bispectral index (BIS). Methods. Twenty-five patients undergoing minor elective surgery were investigated. The number of fluctuations in mean skin conductance (NFSC), BIS and haemodynamic parameters were recorded simultaneously. The performance of the monitoring devices to predict and distinguish between the clinical states ‘steady-state anaesthesia’, ‘first reaction’ and ‘extubation’ were compared using the method of prediction probability (PK) calculation. Results. Both monitors showed similar performance in distinguishing between ‘steady-state anaesthesia’ vs ‘first reaction’ (PK NFSC 0.89; BIS � 0.94) and ‘steady-state anaesthesia’ vs ‘extubation’ (PK NFSC 0.96; BIS � 0.96). The response times of the monitors, to indicate the likelihood of ‘first reaction’, were not significantly different. Conclusions. NFSC, as a parameter of skin conductance, performed similarly to BIS in patients waking after a general anaesthetic. Br J Anaesth 2006; 97: 187–91

In vitro morphine does not reduce cilia beat frequency, a key factor determining bronchial mucus transport velocity. There are no reports about the effect of remifentanil on bronchial mucus transport. We compared the bronchial mucus transport velocity in patients having total intravenous anaesthesia with either propofol and morphine, or propofol and remifentanil. Twenty patients scheduled for elective surgery were randomly allocated to the two groups. Fifteen minutes after insertion of the laryngeal mask airway, bronchial mucus transport velocity was assessed by fibreoptic observation of the movement of methylene blue dye applied to the right main bronchus. Compared with morphine, bronchial mucus transport velocity was significantly reduced in patients receiving remifentanil (morphine mean (SD) 9.2 (5.8) vs remifentanil 4.2 (3.0) mm.min(-1), p = 0.028). Anaesthesia with remifentanil may lead to significantly impaired bronchociliary clearance in comparison to morphine. This could have clinical implications, in particular in patients at risk.

Attenuating intraoperative stress is a key factor in improving outcome. We compared neuroendocrine changes and heart rate variability (HRV) during balanced anesthesia (BAL) versus total IV anesthesia (TIVA). Forty-three patients randomly received either BAL (sevoflurane/remifentanil) or TIVA (propofol/remifentanil). Depth of anesthesia was monitored by bispectral index. Stress hormones were measured at 7 time points (P1 = baseline; P2 = tracheal intubation; P3 = skin incision; P4 = maximum operative trauma; P5 = end of surgery; P6 = tracheal extubation; P7 = 15 min after tracheal extubation). HRV was analyzed by power spectrum analysis: very low frequency (VLF), low frequency (LF), high frequency (HF), LF/HF ratio, and total power (TP). LF/HF was higher in TIVA at P6 and TP was higher in TIVA at P3-7 (P3: 412.6 versus 94.2; P4: 266.7 versus 114.6; P5: 290.3 versus 111.9; P6: 1523.7 versus 658.1; P7: 1225.6 versus 342.6 ms2)). BAL showed higher levels of epinephrine (P7: 100.5 versus 54 pg/mL), norepinephrine (P3: 221 versus 119.5; P4: 194 versus 130.5 pg/mL), adrenocorticotropic hormone (P2 10.5 versus 7.7; P5: 5.3 versus 3.6; P6: 10.9 versus 5.3; P7: 20.5 versus 7.1 pg/mL) and cortisol (P7: 6.9 versus 3.9 microg/dL). This indicates a higher sympathetic outflow using BAL versus TIVA during ear-nose-throat surgery.

Summary Background and objective: The augmentation of the effect of neuromuscular blocking drugs with volatile anaesthetics is well documented, but the mechanism remains unclear. The pharmacological interaction and relative plasma concentrations of mivacurium isomers were investigated during either propofol- or isoflurane-maintained anaesthesia. Methods: Forty-four patients were randomly assigned to one of two groups: isoflurane or propofol. All patients received an initial dose of mivacurium 0.1 mg kg −1 . After recovery of the first twitch (T1) response measured by acceleromyography to 5%, a T1 depression of 90–99% was maintained by infusion. After a steady state was reached, blood samples were taken after 10 and 30 min for analysis of mivacurium isomers. Recovery times for T1 to 25/50/75/90% (TW25–90), train-of-four ratio 25/70% and recovery index (time TW25–75) were recorded after stop of infusion. Results: In the isoflurane group, lower infusion rates were needed (3.0 ± 1.6 versus 3.6 ± 1.6 μg kg −1 min −1 ) and there was a slower recovery (significant for train-of-four ratio 70%: 21.9 versus 17.9 min). The plasma concentrations of mivacurium and its trans – trans isomer (in percentage of the total) were significantly higher in the isoflurane group (10 min: 52.6 versus 25.8%; 30 min: 49.6 versus 23.2%). Conclusions: For mivacurium, the phenomenon of ‘potentiation’ of the effect of muscle relaxants by volatile anaesthetics could be due to an increase in the plasma concentration of the potent trans – trans isomer.

Background Hypotension due to vasodilation during subarachnoid block (SAB) for elective cesarean delivery may be harmful. Heart rate variability (HRV), reflecting autonomic control, may identify patients at risk of hypotension. Methods Retrospectively, HRV was analyzed in 41 patients who were classified into one of three groups depending on the decrease in systolic blood pressure (SBP): mild (SBP > 100 mmHg), moderate (100 > SBP > 80 mmHg), or severe (SBP < 80 mmHg). Prospectively, HRV and hemodynamic data of 19 patients were studied. Relative low frequency (LF), relative high frequency (HF), and LF/HF ratio were analyzed. Results Retrospective analysis of HRV showed a significantly higher sympathetic and lower parasympathetic drive in the groups with moderate and severe compared with mild hypotension before SAB (median, 25th/75th percentiles): LF/HF: mild: 1.2 (0.9/1.8), moderate: 2.8 (1.8/4.6), P < 0.05 versus mild; severe: 2.7 (2.0/3.5), P < 0.05 versus mild. Results were confirmed by findings of LF and HF. Prospectively, patients were grouped according to LF/HF before SAB: low-LF/HF: 1.5 (1.1/2.0) versus high-LF/HF: 4.0 (2.8/4.7), P < 0.05; low-LF: 58 +/- 9% versus high-LF: 75 +/- 10%, P < 0.05; low-HF: 41 +/- 10% versus high-HF: 25 +/- 10%, P < 0.05. High-risk patients had a significantly lower SBP after SAB (76 +/- 21 vs. 111 +/- 12 mmHg; P < 0.05). Conclusions Retrospectively analyzed HRV of patients scheduled to undergo elective cesarean delivery during SAB showed significant differences depending on the severity of hypotension after SAB. Preliminary findings were prospectively confirmed. High LF/HF before SAB predicted severe hypotension. Preoperative HRV analysis may detect patients at risk of hypotension after SAB.