Anaesthesia and Intensive Care

The purpose of this study was to determine the best estimate of glomerular filtration rate (GFR) to adjust vancomycin (VAN) dosage in critically ill patients. Seventy-eight adult intensive care unit patients received a 15 mg/kg loading dose of VAN plus a 30 mg/kg/day continuous infusion. Steady-state concentration was measured 48 hours later and the dose was adjusted to obtain a target concentration ranging from 20 to 25 mg/1. GFR was estimated by measured creatinine clearance (CL_CR), Cockcroft, Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. The required dose providing the target concentration was 36±17 mg/kg/day. The first dosage had to be increased in 51% of all patients and in 84% of trauma patients (highest GFR), but had to be decreased in 17% of patients. The closest relationship between clearances of vancomycin was observed with CKD-EPI to GFR. The correlation between clearances of vancomycin and measured CL_CR was significant but was rather poor with Cockcroft and Modification of Diet in Renal Disease equation. On the Bland and Altman plots, measured CL_CR provided a lower bias but a larger confidence interval and a weaker precision than CKD-EPI. For VAN dose adjustments in intensive care unit patients, Cockcroft formula and Modification of Diet in Renal Disease should be used with caution. In clinical practice, the physician does not have at their disposal the patient's measured CL_CR when prescribing. The CKD-EPI appears to be the best predictor of clearances of vancomycin for calculation of a therapeutic VAN regimen.

Thoracic epidural anaesthesia alone is an applied technique of anaesthesia for nephrectomy which has both advantages and limitations. Dexmedetomidine is a highly selective α₂-adrenoreceptor agonist which has both central and peripheral analgesic properties. Forty patients undergoing nephrectomy were enrolled in this clinical trial and allocated randomly to two groups, a control group (C group) and a dexmedetomidine group (D group). The C group received epidural 0.75% levobupivacaine 12 ml with 1 ml of isotonic sodium chloride solution, while the D group received epidural 0.75% levobupivacaine 12 ml with 1 ml (0.5 μg/kg) of dexmedetomidine. Haemodynamic changes, onset time and duration of sensory and motor block, muscle relaxation score, verbal rating score for pain, sedation score and the total postoperative analgesic consumption were evaluated. Sensory blockade duration was longer in the D group than in the C group (P=0.01). The incidence of motor block and the muscle relaxation score were significantly higher in the D group compared with the C group (P=0.01). Compared with the C group, pain scores were significantly lower in the first four postoperative hours in the D group (two hours rest P=0.038; two hours activity P=0.009; four hours rest P=0.044; four hours activity P=0.003). The total amount of flurbiprofen analgesic was significantly lower in the D group compared with the C group (P=0.03). Epidural dexmedetomidine 0.5 μg/kg appears to intensify thoracic epidural anaesthesia with levobupivacaine.

Pre-procedural ultrasound scanning has been used to facilitate spinal anaesthesia in patients with difficult anatomical landmarks and shown to improve first-attempt success rates in some studies. We studied whether pre-procedural ultrasound scanning improved first-attempt success rate and decreased time taken for the procedure in the general adult population. In this prospective, randomised controlled trial, 170 American Society of Anesthesiologists physical status 1 to 3 patients aged between 21 and 80 years were recruited. Informed consent was obtained. Patients were randomised into two groups, ultrasound-guided identification of landmarks (Ultrasound Group) and manual palpation of landmarks (Manual Palpation Group). The primary outcome was first-attempt success rate and secondary outcomes were time taken to perform procedure, number of needle redirections, patient satisfaction and complications. The first-attempt success rate was 64% in the Ultrasound Group and 52% in the Manual Palpation Group (P=0.16). Time taken for procedure was shorter in the Ultrasound Group compared to the Manual Palpation Group (2.9±3.6 minutes versus 3.9±3.7 minutes, P= 0.007). Patient satisfaction was higher in the Ultrasound Group. There were no differences in complications. As there was no statistically significant difference in first-attempt success rates between the two groups, existing evidence for routine pre-procedural scanning for all patients is inadequate. The current use of pre-procedural ultrasound scanning will probably be limited to selected patients where spinal anaesthesia may be technically challenging with conventional methods.

Reduction of adverse events depends on accurate detection. The utility of a Trigger Tool to detect and classify severity of adverse events in an intensive care unit of a paediatric university hospital was compared to voluntary reporting. Sixty patient records were randomly selected from 314 admissions over three months. Events detected by the Trigger Tool were classified by two independent investigators as insignificant, minor, moderate, major or catastrophic. Examination of each record required, on average, 40 minutes. Ninety-eight adverse events (1.66/patient) were detected in 59 available records. Mean admission was 2.77 days. The incidence of adverse events was 59.9 per 100 patient days or 0.60 events per patient per day. The number of events detected by the Trigger Tool was related to duration of admission (r=0.70, P < 0.0001) and risk of mortality on admission (r=0.50, P=0.0001) but not to age. The inter-rater agreement on detection of adverse events was good. Investigator One detected 66 adverse events while Investigator Two detected 93 events (kappa 0.63). Of the 61 events detected by both investigators, the agreement of classification of severity was very good (kappa 0.89). Of the 56 events rated similarly by both investigators, 13 (23%) were insignificant, 19 (34%) were minor, 17 (30%) were moderate, 4 (7%) were major and 3 (6%) were catastrophic. Only four adverse events had been reported voluntarily, of which two were detected using the Trigger Tool. Whereas the Trigger Tool is a simple, efficient and robust method, voluntary reporting is inadequate and captures very few adverse events in the intensive care unit environment.

The decision to attempt a percutaneous airway in a recognised ‘Can't Intubate, Can't Oxygenate’ (CICO) situation may occur too late to avoid a poor outcome. Our study was designed to investigate the effect of high-fidelity simulation on the confidence and decision-making ability of anaesthesia trainees in managing CICO scenarios in subsequent simulation. Nine anaesthesia trainees from Logan Hospital participated. Pre-study questionnaires surveying confidence levels in various anaesthetic crises were completed. All participants underwent an education session based on algorithms developed for failed intubation and ventilation, and techniques for securing percutaneous airway access. However, only four of the nine participated in a high-fidelity simulation session. All nine participants were then filmed during ‘mini-simulation’ assessment sessions and completed post-study questionnaires identical to those at the commencement of the study. The four trainees who had undertaken the initial high-fidelity simulation had a lower median time to laryngeal mask airway attempt (60 versus 115 seconds) and time to percutaneous airway attempt (111 versus 172 seconds) in the subsequent simulation. The median number of deviations from the Difficult Airway Society algorithm was 0 for the simulation group compared to 1 for the non-simulation group. This small study suggests that high-fidelity simulation shortens the decision-making time of anaesthesia trainees in subsequent simulated CICO scenarios. This observation warrants follow-up in larger prospective trials.

Rapid Response Teams (RRT) are specialised teams that review deteriorating ward patients in an attempt to prevent morbidity and mortality. Most studies have assessed the effect of implementing an RRT into a hospital. There is much less literature on the characteristics and outcomes of RRT patients themselves. This article reviews the epidemiology of adult RRT patients in Australia and proposes three models of RRT syndromes. The number of RRT calls varies considerably in Australian hospitals from 1.35 to 71.3/1000 hospital admissions. Common causes of RRT calls include sepsis, atrial fibrillation, seizures and pulmonary oedema. Approximately 20% of patients to whom an RRT has responded have more than one RRT call, and up to one-third have issues around end-of-life care. Calls are least common overnight. Between 10 to 25% of patients are admitted to a critical care area after the call. The in-hospital mortality for RRT patients is approximately 25% overall but only 15% in patients without a limitation of medical therapy. RRT syndromes can be conceptually described by the trigger for the call (e.g. hypotension) or the clinical condition causing the call (e.g. sepsis). Alternatively, the RRT call can be described by the major theme of the call: “end-of-life care”, “requiring critical care” and “stable enough to initially remain on the ward”. Based on these themes, education strategies and quality improvement initiatives may be developed to reduce the incidence of RRT calls, further improving patient outcome.

The aim of this study was to investigate the effects of different general anaesthesia techniques on immune responses in patients undergoing surgery for tongue cancer. Sixty American Society of Anesthesiologists physical status 1 or 2 patients undergoing elective reconstructive surgery for tongue cancer were randomised to three groups. Group 1 received propofol induction and maintenance (TIVA), group 2 received propofol induction and sevoflurane maintenance (MIXED) and group 3 received sevoflurane induction and maintenance (SEVO). All patients received an infusion of remifentanil. Blood samples were obtained at eight time-points: 30 minutes before induction (T₀); one hour (T₁), three hours (T₂) and five hours (T₃) after induction; at the end of the operation (T₄); and 24 hours (T₃), 48 hours (T₆) and 72 hours (T₇) after operation. The T lymphocyte subsets (including CD3⁺ cells, CD3⁺CD4⁺ cells and CD3⁺CD8⁺ cells) and CD4⁺/CD8⁺ ratio, natural killer cells and B lymphocytes were analysed by flow cytometry. All immunological indicators except CD3⁺CD8⁺ cells were significantly decreased in all groups at T₁∼T₅ compared to T₀ (P <0.05). The percentages of CD3⁺ cells, CD3/ CD4⁺ cells and natural killer cells, and the CD4/CD8+ ratios were significantly lower in the MIXED groups and SEVO groups but not the TIVA group at T₆ as compared with T₀ (P <0.05). There were minor but statistically significant differences in the percentages of CD3⁺ cells, CD3⁺CD4⁺ cells and natural killer cells, and the CD4/CD8⁺ ratios between the SEVO group and the TIVA group at T₂∼T₆ (P <0.05). These findings suggest that propofol has slightly less effect on cellular immune responses than sevoflurane.

Aminoglycosides are a class of antibiotics that are commonly used in the treatment of gram-negative pathogens in the critically ill population. Unfortunately, dosing of these aminoglycosides in critically ill patients is difficult due to their altered pharmacokinetics in the critically ill and narrow therapeutic index. In this study, we evaluated whether a limited sampling strategy can be used to predict the area under the concentration (AUC) curve of amikacin concentrations over a 24-hour period after a single dose of intravenous amikacin (25 mg/kg). This open-labelled, non-comparative prospective study recruited 20 adult critically ill trauma patients with a diagnosis of hospital-acquired infection. We assessed the best estimate of plasma amikacin concentrations over a 24-hour period by multiple stepwise regression, using nine blood samples during this study period as the gold standard. Using a jackknife procedure, the AUC of amikacin over a 24-hour period was estimated by choosing a combination of the amikacin concentrations measured at different time-points. Overall, the mean prediction error of all models was not statistically different from zero (P >0.05). Based on bias and imprecision, all models gave good estimate of AUC of amikacin over a 24-hour period, but a two-point sampling strategy at 1.5 and 6 hours post-dose appeared to offer the best compromise between accuracy and cost-effectiveness in optimising the dosing of amikacin in critically ill patients.

The study aim was to investigate the effect of three different morphine doses added to levobupivacaine 0.125% for caudal analgesia after circumcision surgery in children, particularly in relation to the frequency of postoperative vomiting within the first 24 hours following surgery. Two hundred and forty patients aged 5 to 12 years undergoing circumcision were included in the study. Following induction, caudal 0.125% levobupivacaine 0.5 ml/kg was given after adding 7.5, 10 or 15 μg/kg morphine. The postoperative incidence of vomiting was 5%, 12.5% and 17.5% in the groups 7.5, 10 and 15 μg/kg morphine, respectively (P=0.012, 7.5 versus 15 μg/kg groups). Five percent of the 7.5 μg/kg group and none of the patients in the other groups required paracetamol within the first 12 hours, and there was a significantly greater need for rescue paracetamol over the 24 hours in the 7.5 group versus the 15 μg/kg group (P=0.013). Postoperative analgesic durations were long and did not differ between groups (1273±338, 1361±192 and 1426±48 minutes, respectively, P=0.08). In conclusion, because the incidence of vomiting is very low, the duration of postoperative analgesia is long and a dose of 7.5 μg/kg caudal morphine is much lower than doses previously reported to be associated with respiratory depression, this study supports the use of 7.5 μg/kg caudal morphine added to 0.125% levobupivacaine for circumcision surgery.

This retrospective observational cohort study compared glycaemic control and long-term outcomes following transition from a modified intensive insulin therapy (mIIT) regimen to conventional glycaemic control (CGC) in adult patients admitted to a tertiary adult general intensive care unit, during two 24-month periods, before and after the publication of the Normoglycemia in Intensive Care Evaluation and Surviving Using Glucose Algorithm Regulation (NICE-SUGAR) trial. The before NICE-SUGAR cohort received mIIT (target glycaemic ranges 4.4 to 7.0 mmol/1), while the after NICE-SUGAR cohort received CGC (target glycaemic range 7.1 to 9.0 mmol/1). A total of 5202 patients were included in the study. With transition from mIIT to CGC, the mean time-weighted glucose increased from 6.94 mmol/1 to 8.2 mmol/1 (P <0.0001). A similar increase was observed in other glycaemic indices (mean, highest and lowest glucose values, P <0.0001 for all). The adjusted 90-day odds ratio for mortality decreased by 47% with transition from mIIT to CGC (odds ratio 1.47 (95% confidence interval, 1.22 to 1.78) (P <0.0001). The rate of severe and moderate hypoglycaemia also decreased from 1.2 to 0.4% (P=0.004) and from 23.3 to 5.9% (P <0.0001), respectively. mIIT was associated with an increased risk of moderate and severe hypoglycaemia compared to CGC (odds ratio 3.1 (1.51 to 6.39) (P=0.002), 6.29 (5.1 to 7.75) (P <0.0001)). Changes in recommended glycaemic control were translated into practice, with increased glycaemic indices and decreased rates of severe and moderate hypoglycaemia after the introduction of CGC. The associated decrease in 90-day mortality suggests mIIT was not superior to CGC, despite a lower hypoglycaemia rate than in previous IIT trials. Our findings support the continued use of CGC.

Normocapnia is recommended in intensive care management of patients after out-of-hospital cardiac arrest. While normocapnia is usually achievable, it may be therapeutically challenging, particularly in patients with airflow obstruction. Conventional mechanical ventilation may not be adequate to provide optimal ventilation in such patients. One of the recent advances in critical care management of hypercapnia is the advent of newer, low-flow extracorporeal carbon dioxide clearance devices. These are simpler and less invasive than conventional extracorporeal devices. We report the first case of using a novel, extracorporeal carbon dioxide removal device in Australia on a patient with out-of-hospital cardiac arrest where mechanical ventilation failed to achieve normocapnia.

Little research has been carried out into the infusion of intravenous sterile water for the treatment of hypernatraemia, and it remains a contentious issue. We conducted a review of the literature and extract results following an extensive search of Medline 1946, Embase 1974, ProQuest, evidence-based practice resources, national and international guideline sites and the publications of various professional bodies. The review is presented on the infusion of sterile water (hypotonic fluid) to lower serum sodium level in those circumstances when enteral supplementation of water is not possible, such as in postoperative patients or when other isotonic fluids (such as 5% dextrose in water infusion) are less than ideal—for example, hyperglycaemic patients on an insulin infusion. Absence of guidelines has limited the use of sterile water, even as an off-label drug when it can be administered relatively safely via a central line.