Augmented renal clearance (ARC) refers to increased solute elimination by the kidneys. ARC has considerable implications for altered drug concentrations. The aims of this study were to describe the prevalence of ARC in a select cohort of patients admitted to a Malaysian intensive care unit (ICU) and to compare measured and calculated creatinine clearances in this group. Patients with an expected ICU stay of <24 hours plus an admission serum creatinine concentration <120 µmol/l, were enrolled from May to July 2013. Twenty-four hour urinary collections and serum creatinine concentrations were used to measure creatinine clearance. A total of 49 patients were included, with a median age of 34 years. Most study participants were male and admitted after trauma. Thirty-nine percent were found to have ARC. These patients were more commonly admitted in emergency (P=0.03), although no other covariants were identified as predicting ARC, likely due to the inclusion criteria and the study being under-powered. Significant imprecision was demonstrated when comparing calculated Cockcroft-Gault creatinine clearance (Crcl) and measured Crcl. Bias was larger in ARC patients, with Cockcroft-Gault Crcl being significantly lower than measured Crcl (P <0.01) and demonstrating poor correlation (rs=-0.04). In conclusion, critically ill patients with 'normal' serum creatinine concentrations have varied Crcl. Many are at risk of ARC, which may necessitate individualised drug dosing. Furthermore, significant bias and imprecision between calculated and measured Crcl exists, suggesting clinicians should carefully consider which method they employ in assessing renal function.
In this prospective, randomized controlled trial, changes in endotracheal tube cuff pressure were studied in 60 patients undergoing elective surgery under general anaesthesia with nitrous oxide and oxygen. The cuffs were inflated with either air or distilled water. The mean pressure in the air-filled cuffs increased steadily throughout the procedure, reaching 47.5 +/- 7.3 cmH2O at one hour compared with 31.6 +/- 2.4 cmH2O mean pressure in the water-filled cuffs. The pressure and the rate of rise in cuff pressure were significantly lower (P<0.05) in the water-filled cuffs throughout the hour of study. When an endotracheal tube cuff is distended with water, the rise in cuff pressure during nitrous oxide anaesthesia is lower than that of an air-filled cuff.
We compared the performance of the LMA Supreme (SLMA) with the I-Gel during anaesthesia in spontaneously breathing adult patients. Ninety patients with American Society of Anesthesiologists physical status I or II were studied in a prospective randomised controlled study. Our primary outcome measure was oropharyngeal leak pressure. We also compared the overall insertion success rate, ease of insertion, adequacy of ventilation and incidence of complications. The mean (SD), oropharyngeal leak pressure for the SLMA was 25.6 (5.1) cmH2O, which was greater than for the I-Gel 20.7 (5.9) cmH2O (P = 0.0001). The first attempt and overall insertion success rates were similar between the two groups (SLMA 97.8 and 97.8%; I-Gel 93.3 and 100%, P = 0.132). The SLMA was rated easier to insert than the I-Gel (P = 0.011), but the time taken for insertion (P = 0.433) was similar. The incidence of complications was low in both groups. The grade of fibreoptic view was better with the I-Gel than the SLMA (P = 0.001). We conclude that in adults with normal airways, the SLMA is easier to insert and provides a higher oropharyngeal leak pressure, but fibreoptic views are better with the i-gel.
Propofol anaesthesia using target control infusion during cardiac surgery has become more popular recently. However, without depth of anaesthesia monitoring, the standard target concentration used may be higher than necessary to maintain adequate hypnosis during hypothermic cardiopulmonary bypass. The purpose of this study was to evaluate the effect of bispectral index monitoring on propofol administration during hypothermic cardiopulmonary bypass. After ethics committee approval and written informed consent, 20 New York Heart Association class I-III patients scheduled for elective cardiac surgery requiring hypothermic cardiopulmonary bypass were studied in this prospective randomised controlled trial. In group C, routine anaesthesia was practised, where patients received propofol at target concentration between 1.5 to 2.5 microg/ml during cardiopulmonary bypass. In group B, the target concentration was titrated to a bispectral index value of 40 to 50. Mean arterial pressure and bispectral index were recorded at various time intervals. The use of propofol, phenylephrine, sodium nitroprusside and adrenaline were recorded. The median propofol administration in group B was significantly less than that in group C (2.9 mg/kg/h compared to 6.0 mg/kg/h). The bispectral index value during bypass was significantly lower in group C than in group B, reflecting a deeper state of anaesthesia. There was no difference in the use of inotropes, vasoconstrictors or vasodilators. Bispectral index monitoring enables a 50% reduction in propofol administration at this standard dose during hypothermic cardiopulmonary bypass.
We have compared the use of the laryngeal mask airway with the new modified laryngeal tube in a prospective randomized controlled study. Sixty ASA 1 or 2 patients, aged 18 to 65 years, scheduled for elective surgery and breathing spontaneously under general anaesthesia, were studied. After preoxygenation, anaesthesia was induced with fentanyl and propofol. The patients were randomized to receive either a laryngeal mask airway or a laryngeal tube. Anaesthesia was maintained with nitrous oxide, oxygen and isoflurane. We recorded the speed and the ease of insertion, the number of attempts needed to successfully secure the airway and intraoperative complications, such as partial airway obstruction needing airway manipulation. The airway devices were removed with the patients fully awake at the end of surgery. Systolic arterial blood pressure, heart rate and end-tidal CO2 were recorded at various time intervals. Postoperative complications were recorded. We found that the incidence of partial airway obstruction needing intraoperative airway manipulation was higher with the laryngeal tube than with the laryngeal mask airway. We conclude that during spontaneous ventilation the modified laryngeal tube is not as reliable in providing a satisfactory airway and we consider it is not a suitable alternative to the laryngeal mask airway.
This is a preliminary report on the use of the modified Airway Management Device in 50 spontaneously breathing patients undergoing elective day care surgery. We were successful in establishing a clear airway in all 50 patients, 46 of these patients had a patient airway on the first attempt. All patients were successfully managed with the Airway Management Device throughout the surgery. Partial airway obstruction during maintenance of anaesthesia occurred in three cases requiring only minor manipulations. Our result showed that the Airway Management Device may be used as an alternative airway management in anaesthesia.
Thyroid eye disease is an autoimmune inflammatory disorder of the orbit in adults. It causes inflammation, expansion and fibrosis of orbital fat, muscles and the lacrimal gland, leading to facial disfigurement, functional disability and, in severe cases, blindness. Overall, approximately 20% of affected patients need some form of surgical intervention requiring anaesthesia. This narrative review explores the background of thyroid eye disease, surgical procedures performed and their implications for anaesthesia. General anaesthesia is used for orbital decompression procedures, strabismus correction surgery and complex oculoplastic procedures. Local anaesthetic infiltration or regional anaesthesia under monitored anaesthesia care are the techniques most commonly employed for eyelid retraction surgery. It is important to limit the volume of local anaesthetic agent used during infiltration and continuously monitor the orbital volume and ocular pressure with a ballottement technique. In addition, the contralateral eye should be checked and, if necessary, protected against corneal exposure. Retrobulbar, peribulbar and sub-Tenon's blocks are best avoided. Topical anaesthesia has been used for some strabismus correction surgery but its use is limited to motivated and cooperative patients only.
Ocular hypotony can occur from many causes, including eye trauma, ophthalmic surgery and ophthalmic regional anaesthesia-related complications. Some of these patients require surgical intervention(s) necessitating repeat anaesthesia. While surgical management of these patients is well described in the literature, the anaesthetic management is seldom discussed. The hypotonous eye may also have altered globe anatomy, meaning that the usual ocular proprioceptive feedbacks during regional ophthalmic block may be altered or lost, leading to higher risk of inadvertent globe injury. In an 'open globe' there is a risk of sight-threatening expulsive choroidal haemorrhage as a consequence of ophthalmic block or general anaesthesia. This narrative review describes the physiology of aqueous humour, the risk factors associated with ophthalmic regional anaesthesia-related ocular hypotony, the surgical management, and a special emphasis on anaesthetic management. Traumatic hypotony usually requires urgent surgical repair, whereas iatrogenic hypotony may be less urgent, with many cases scheduled as elective procedures. There is no universal best anaesthetic technique. Topical anaesthesia and regional ophthalmic block, with some technique modifications, are suitable in many mild-to-moderate cases, whilst general anaesthesia may be required for complex and longer procedures, and severely distorted globes.
Two recent cases of central retinal artery occlusion under otherwise uncomplicated sub-Tenon's block that resulted in significant visual loss after cataract surgery prompted us to undertake a literature review of such cases. We identified 97 cases of retinal artery occlusion after ophthalmic surgery under regional anaesthesia that had no immediate signs of block-related complications. These occurred after various intraocular (87%) and extraocular (13%) operations, across a wide range of ages (19-89 years) on patients with (59%) or without (39%) known risk factors. The anaesthetic techniques included 40 retrobulbar blocks, 36 peribulbar blocks, 19 sub-Tenon's blocks, one topical anaesthetic and one unspecified local anaesthetic. Different strengths of lidocaine, bupivacaine, mepivacaine and ropivacaine, either alone or in various combinations, were used. The details of the anaesthetic techniques were often incomplete in the reports, which made comparison and analysis difficult. Only nine cases had their cause (optic nerve sheath injury) identified, while the mechanism of injury was unclear in the remaining patients. Various mechanisms were postulated; however, the cause was likely to be multifactorial due to patient, surgical and anaesthetic risk factors, especially in those with compromised retinal circulation. As there were no definite risk factors identified, no specific recommendations could be made to avoid this devastating outcome. We have provided rationales for some general considerations, which may reduce this risk, and propose anaesthetic options for ophthalmic surgery on the fellow eye if required, based both on our literature review and our personal experience.
The aim of this prospective, double-blind, randomized, placebo-controlled clinical trial was to investigate whether the administration of ketamine before induction with propofol improves its associated haemodynamic profile and laryngeal mask airway (LMA) insertion conditions. Ninety adult patients were randomly allocated to receive either ketamine 0.5 mg x kg(-1) (n = 30), fentanyl 1 microg x kg(-1) (n = 30) or normal saline (n = 30), before induction of anaesthesia with propofol 2.5 mg x kg(-1). Insertion of the LMA was performed 60s after injection of propofol. Arterial blood pressure and heart rate were measured before induction (baseline), immediately after induction, immediately before LMA insertion, immediately after LMA insertion and every minute for three minutes after LMA insertion. Following LMA insertion, the following six subjective endpoints were graded by a blinded anaesthestist using ordinal scales graded 1 to 3: mouth opening, gagging, swallowing, movement, laryngospasm and ease of insertion. Systolic blood pressure was significantly higher following ketamine than either fentanyl (P = 0.010) or saline (P = 0.0001). The median (interquartile range) summed score describing the overall insertion conditions were similar in the ketamine [median 7.0, interquartile range (6.0-8.0)] and fentanyl groups [median 7.0, interquartile range (6.0-8.0)]. Both appeared significantly better than the saline group [median 8.0, interquartile range (6.75-9.25); P = 0.024]. The incidence of prolonged apnoea (> 120s) was higher in the fentanyl group [23.1% (7/30)] compared with the ketamine [6.3% (2/30)] and saline groups [3.3% (1/30)]. We conclude that the addition of ketamine 0.5 mg x kg(-1) improves haemodynamics when compared to fentanyl 1 microg x kg(-1), with less prolonged apnoea, and is associated with better LMA insertion conditions than placebo (saline).
The Australian and New Zealand College of Anaesthetists (ANZCA) has more than 200 accredited training sites in Australia, New Zealand, Hong Kong, Malaysia and Singapore, many of which participate in ANZCA Clinical Trials Network (CTN)-endorsed clinical trials. We undertook a survey of accredited sites to determine research capability, activity and potential. With ethics committee approval an electronic survey was distributed to accredited sites in July 2015. Of 207 accredited sites, 167 were sent the questionnaire (after eliminating ineligible sites) and 128 responded. Response rates for Australia, New Zealand, Hong Kong, Malaysia and Singapore were 100%, 100%, 35%, 25% and 75% respectively. Forty-four (34%) of 128 responding sites had a head of research; 101 (80%) of 126 responding sites were active in research; 42 (33%) of 126 responding sites had no publications since January 2011 and 15 (12%) had >50 publications; 95 (76%) of 125 responding sites had at least one specialist anaesthetist engaged in research (median = 4 [range 1-25]); and 45 (36%) of 125 responding sites had at least one research coordinator (median = 2 [range 1-15]). Fifty-eight (28%) of the 207 accredited sites were identified as participating in recent ANZCA CTN-endorsed clinical trials. Research capability and activity were higher in these sites. This survey has identified a strong base upon which to expand clinical trial activity, and regions, sectors, investigators and research coordinators who may benefit from additional support.
Factors that governed the setting up of a multipurpose, temporary Intensive Care Unit of six beds, in a remote area of Malaysia and the experience of operating it for more than two and a half years are outlined.
We report our use of a superficial cervical plexus block to manage three adults who presented for drainage of dental abscesses. All patients had difficult airways related to severe trismus (preoperative inter-incisor distance < or = 1.5 cm). The first two patients, whose abcesses involved both the submandibular and submasseteric spaces, were managed with combined superficial cervical plexus and auriculotemporal nerve block. In a third patient, a superficial cervical plexus block alone was sufficient because the abscess was confined to the submandibular region. The blocks were successful in all three cases with minimal requirement for supplemental analgesia. We recommend the consideration of superficial cervical plexus block, and if necessary an auriculotemporal nerve block, for the management of selected patients with difficult airways who present for drainage of dental abcesses.
Differences in sensitivity to anaesthetic drugs may exist among different ethnic groups. Allelic variants for drug metabolizing isoenzymes and pharmacokinetic differences may account for a variable response to some anaesthetic drugs. This study was designed to compare propofol consumption and recovery characteristics in four ethnic groups: Chinese, Malays, and Indians in Malaysia and Caucasians in Italy. Patients undergoing total intravenous anaesthesia with propofol and fentanyl were evaluated for propofol consumption and recovery time. The Bispectral Index (BIS) was used to maintain the same anaesthesia depth in all patients. The BIS value, the response to verbal stimuli and eye-opening time were used to assess recovery. After propofol discontinuation the BIS values returned to baseline in 11+/-4.2 min for Caucasians, in 12.5+/-5.1 min for Chinese, 15.9+/-6.3 min for Malays and 22.1+/-8.1 for Indians. Time to eye-opening was 11.63+/-4.2 min in Caucasians, 13.23+/-4.9 min in Chinese, 16.97+/-5.2 min in Malays and 22.3+/-6.6 min in Indians. The propofol consumption was significantly lower in Indians compared to the other three groups (P<0.01). The recovery of Indians was much slower compared to Chinese, Malays and Caucasians. The recovery time of Malays is significantly slower compared to Chinese and Caucasians. Differences in propofol consumption and recovery time were not significant between Chinese and Caucasians, but the ratio recovery time/propofol consumption was significantly lower in Caucasians compared to all the other groups.
In a double-blind, placebo-controlled clinical trial (power of 80% to detect a 30% reduction in morphine consumption, P < 0.05), we have determined that the administration of two doses of intravenous ketoprofen 100 mg, one at the end of surgery and the second 12 hours postoperatively, was associated with a significant reduction in morphine consumption at eight (P = 0.028), 12 (P = 0.013) and 24 hours (P = 0.013) but not four hours (P = 0.065) postoperatively, as compared to placebo, when assessed by patient-controlled analgesia. There was no difference between the groups in pain scores or in the incidence of nausea and vomiting. One patient in the placebo group suffered from excessive sedation while one patient from the ketoprofen group suffered from transient oliguric renal failure. There were no other adverse effects. The results of this study show that ketoprofen does provide a morphine-sparing effect in the management of postoperative pain after abdominal surgery.
Newer second generation supraglottic airway devices may perform differently in vivo due to material and design modifications. We compared performance characteristics of the Ambu® AuraGain™ and LMA Supreme™ Second Seal™ in 100 spontaneously breathing anaesthetised patients in this randomised controlled study. We studied oropharyngeal leak pressures (OLP) (primary outcome) and secondarily, ease of insertion, success rates, haemodynamic response, time to insertion, and complications of usage. We found no significant difference in OLP between the AuraGain versus the LMA Supreme, mean (standard deviation, SD) 24.1 (7.4) versus 23.6 (6.2) cmH2O, P=0.720. First-attempt placement rates of the AuraGain were comparable to the LMA Supreme, 43/50 (86%) versus 39/50 (78%), P=0.906, with an overall 98% insertion success rate for the AuraGain and 88% for the LMA Supreme after three attempts, P=0.112. However, the AuraGain was deemed subjectively harder to insert, with only 24/50 (48%) versus 37/50 (74%) of AuraGain insertions being scored 1 = easy (on a 5 point scale), P=0.013, and also took longer to insert, 33.4 (SD 10.9) versus 27.3 (SD 11.4) seconds, P=0.010. The AuraGain needed a smaller volume of air (16.4 [SD 6.8] versus 23.0 [SD 7.4] ml, P <0.001) to attain intracuff pressures of 60 cmH2O, facilitated more successful gastric tube insertion (100% versus 90.9%, P=0.046), and had significantly decreased sore throat incidence (10% versus 38%, P=0.020). One AuraGain and six LMA Supremes failed to be placed within the stipulated 120 seconds trial definition of 'success'; these patients had risk factors for failed supraglottic insertion. In conclusion, both devices had similar OLPs and performed satisfactorily. However, the AuraGain resulted in less postoperative sore throat despite being harder to and taking longer to, insert.
This randomized controlled trial compared Bispectral Index (BIS) values in 40 patients after a modified rapid sequence induction using thiopentone 4 mg/kg or propofol 2 mg/kg with rocuronium 0.6 mg/kg as muscle relaxant. Endotracheal intubation was performed at 60 seconds from induction of anaesthesia and BIS values were recorded for three minutes after induction. At the 120, 150 and 180 second measurements there was a significantly greater proportion of subjects with BIS values < or = 60 ("anaesthetized") in the propofol group compared with the thiopentone group (P values < 0.02, < 0.01 and < 0.01 respectively). All intubations were completed within two minutes. No explicit recall of intubation was detected clinically with either induction agent. The BIS scores we have measured suggest that thiopentone 4 mg/kg is more likely to be associated with lighter planes of anaesthesia and consequent risk of awareness than propofol 2 mg/kg, if intubation is delayed or prolonged.