Anaesthesia and Intensive Care

The development of effective cryopreservation techniques for both red blood cells and platelets, which maintain ex vivo biological activity, in combination with frozen plasma, provides for a unique blood banking strategy. This technology greatly enhances the storage life of these products. The rationale and potential advantages of using cryopreservation techniques for the provision of blood products to remote and military environments have been effectively demonstrated in several conflicts over the last decade. Current haemostatic resuscitation doctrine for the exsanguinating patient supports the use of red blood cells, platelets and frozen plasma early in the resuscitation. We believe an integrated fresh–frozen blood bank inventory could facilitate provision of blood products, not only in the military setting but also in regional Australia, by overcoming many logistic and geographical challenges. The processes involved in production and point of care thawing are sufficiently well developed and achievable to make this technology a viable option. The potential limitations of cryopreservation and subsequent product thawing need to be considered if such a strategy is to be developed. A substantial body of international experience using cryopreserved products in remote settings has already been accrued. This experience provides a template for the possible creation of an Australian integrated fresh–frozen blood bank inventory that could conceivably enhance the care of patients in both regional Australia and in the military setting.

Horner's syndrome appears when the three-neuron sympathetic pathway is interrupted anywhere from the posterior-lateral nuclei of the hypothalamus through the spinal cord to the eye. In children, Horner's syndrome can be either congenital or acquired, but overall it is a rare finding. There are several causes of Horner's syndrome, some of iatrogenic. Although uncommon in the paediatric population, prompt recognition of the syndrome and immediate treatment may prevent permanent damage to the neuronal pathway. Awareness of the risk of developing iatrogenic Horner's syndrome and early detection of signs are recommended to minimise future disability.

Glutamine is considered an essential amino acid during stress and critical illness. Parenteral glutamine supplementation in critically ill patients has been shown to improve survival rate and minimise infectious complications, costs and hospital length-of-stay. However, glutamine supplementation in patients receiving enteral nutrition and the best method of administration are still controversial. The purpose of this article is to provide a narrative review of the current evidence and trials of enteral and parenteral glutamine supplementation in multiple trauma patients.

A search in PubMed and EMBASE was conducted and relevant papers that investigated the effect of enteral or parenteral glutamine supplementation in patients with multiple trauma were reviewed.

Although recent nutritional guidelines recommend that glutamine supplementation should be considered in these patients, further well-designed trials are required to provide a confirmed conclusion. Due to the inconclusive results of enteral glutamine supplementation trials in patients receiving enteral nutrition, future trials should focus on intravenous glutamine supplementation in patients requiring enteral nutrition and on major clinical outcome measures (e.g. mortality rate, infectious complications).

Post-anaesthetic advice imparted to breastfeeding mothers can vary. This is due in part to the differing information from published data, product information sheets and inevitably from the unhindered flow of opinions available on the internet. This literature review examined the evidence relating to drugs commonly used in the modern anaesthetic setting and their impact on breastfed children. It suggests that special precautions are rarely warranted in the post-anaesthetic care of breastfeeding patients.

Previous studies have shown that spontaneous breathing trials (SBT) with a T-tube or low-level pressure support are comparable. However, low-level pressure support may overestimate the ability of a patient to sustain spontaneous breathing, resulting in premature extubation. Understanding factors contributing to different responses by patients to the two SBT methods aids in clarifying the limitation of using low-level pressure support for SBT. We performed a prospective observational study in 80 consecutive adult patients with mechanical ventilation to identify the factors contributing to different responses of a patient to the two SBT methods. The 80 patients underwent both a T-tube trial and pressure support ventilation of 6 cmH₂O (PS-6) on the day of extubation. Stratified analysis was used to evaluate the effects of age, respiratory compliance and resistance, PaO₂/FiO₂ ratio and underlying disease on post-SBT responses. Comparing the responses to a T-tube trial and PS-6, the patients with old age, poor pulmonary compliance (≤40 ml/cmH₂O) and chronic obstructive pulmonary disease had a higher heart rate (difference [95% CI]: 4 [0,8], 5 [2,9], 5 [0,10] beats/minute, respectively) and systolic blood pressure (10 [4,16], 11 [5,16], 7 [0,13] mmHg, respectively) after the T-tube trial. In conclusion, this research shows that old age and impaired respiratory mechanics contribute to different responses to spontaneous breathing trials with a T-tube and low-level pressure support. Further studies are needed to compare the effectiveness of the two SBT methods in predicting successful extubation in such patient groups.

Pain and postoperative nausea and vomiting (PONV) are common problems after gynaecologic laparoscopy. Two recent studies have shown that morphine requirements and PONV are lower when a LMA ProSeal™ is used, rather than an endotracheal tube (ETT), for female patients undergoing breast and gynaecological surgery. We conducted a patient and observer-blinded randomised controlled trial, recruiting non-obese women without gastro-oesophageal reflux undergoing laparoscopic gynaecological surgery. Patients received a standardised relaxant general anaesthetic and then were randomised to receive either an LMA ProSeal or an endotracheal tube. Patients were assessed at two and 24 hours post-anaesthesia. The primary outcome was postoperative pain score and secondary endpoints included morphine consumption, postoperative emesis and adverse upper airway symptoms.

We recruited 116 patients to the study, 57 patients in the ETT group and 59 patients in the LMA ProSeal group. The patients were similar in demographic and surgical characteristics. At two hours, the ETT group was similar to the LMA ProSeal group in regards to pain scores (verbal rating scale 3.0 vs 3.5, P=0.86), morphine consumption (7.2 vs 7.4 mg, P=0.56) and PONV (47.4 vs 47.5%, P=0.99). After 24 hours, pain scores and PONV rates were also similar. No significant difference in rates of sore throat or dysphagia was observed between the ETT and LMA ProSeal groups. No significant complications were attributable to either airway device.

The LMA ProSeal did not decrease pain or PONV in patients undergoing gynaecological laparoscopy when compared to endotracheal intubation.

This randomised, double-blind study was designed to compare the duration of analgesia and adverse effects following intrathecal administration of dexmedetomidine or clonidine, both with bupivacaine, in trauma patients. Ninety adult trauma patients of American Society of Anesthesiologists physical status I—II, scheduled for lower limb surgery under subarachnoid block, were randomly allocated to one of three groups. All groups received hyperbaric bupivacaine 0.5% 3 ml, to which was added saline 0.5 ml (Group B): clonidine 50 μg (Group C) or dexmedetomidine 5 μg (Group D). The onset and duration of sensory and motor blockade, severity of postoperative pain, time to first rescue analgesia and total analgesic requirement for 24 hours were noted. There was no significant difference in the onset time of the block but the duration of sensory and motor blockade was prolonged in Groups C and D, compared with Group B. The time to analgesia was significantly prolonged in Group D (824±244 minutes) compared with Group C (678±178 minutes; P=0.01), the latter being longer than Group B (406±119 minutes; P=0.0001). Postoperative pain scores were lower in Groups C and D compared with Group B. The requirement for rescue analgesia during the first 24 postoperative hours was significantly less in Groups C and D as compared to Group B (P=0.0001), but comparable between Group C and D (P=0.203). In conclusion, dexmedetomidine 5 μg added to intrathecal bupivacaine 15 mg produces longer postoperative analgesia than clonidine 50 μg among trauma patients undergoing lower limb surgery.

A strong relationship between patient data and preoperative clinical decisions could potentially be used to support clinical decisions in preoperative management. The aim of this exploratory study was to determine the relationship between key patient data and pooled clinical opinions on management.

In a previous study, panels of anaesthetists compared the quality of computer-assisted patient health assessments with outpatient consultations and made decisions on the need for preoperative tests, no preoperative outpatient assessment, possible postoperative intensive care unit/high dependency unit requirements and aspiration prophylaxis. In the current study, the relationship between patient data and these decisions was examined using binomial logistic regression analysis. Backward stepwise regression was used to identify independent predictors of each decision (at P <0.15), which were then incorporated into a predictive model.

The number of factors related to each decision varied: blood picture (four factors), biochemistry (six factors), coagulation studies (three factors), electrocardiography (eight factors), chest X-ray (seven factors), preoperative outpatient assessment (17 factors), intensive care unit requirement (eight factors) and aspiration prophylaxis (one factor). The factor types also varied, but included surgical complexity, age, gender, number of medications or comorbidities, body mass index, hypertension, central nervous system condition, heart disease, sleep apnoea, smoking, persistent pain and stroke. Models based on these relationships usually demonstrated good sensitivity and specificity, with receiver operating characteristics with the following areas under curve: blood picture (0.75), biochemistry (0.86), coagulation studies (0.71), electrocardiography (0.90), chest X-ray (0.85), outpatient assessment (0.85), postoperative intensive care unit requirement (0.88) and aspiration prophylaxis (0.85). These initial results suggest modelling of patient data may have utility supporting clinicians’ preoperative decisions.

Extracorporeal membrane oxygenation (ECMO) is known to affect pharmacokinetics and hence optimum dosing. The aim of this open label, prospective study was to investigate the pharmacokinetics of oseltamivir (prodrug) and oseltamivir carboxylate (active metabolite) during ECMO. Fourteen adult patients with suspected or confirmed H1N1 influenza were enrolled in the study. Oseltamivir 75 mg was enterally administered twice daily and blood samples for pharmacokinetic assessment were taken on day 1 and 5. A multi-compartmental model to describe the pharmacokinetics of oseltamivir and oseltamivir carboxylate was developed using a nonlinear mixed effects modelling approach.

The median (range) clearance of oseltamivir carboxylate was 15.8 (4.8–36.6) 1/hour, lower than the reported mean value of 21.5 1/hour in healthy adults. The median (range) steady state volume of distribution of oseltamivir carboxylate was 179 (61–436) litres, much greater than healthy adults but similar to previous reports in critically ill patients. Substantial ‘between subject’ variability in systemic exposure to oseltamivir carboxylate was revealed; median (range) area under the curve and C_max were 4346 (644–13660) ng/hour/ml and 509 (54–1277) ng/ml, respectively. Both area under the curve and C_max were significantly correlated with serum creatinine (r²=0.37, P=0.02 and r²=0.29, P=0.02, respectively).

Systemic exposure to oseltamivir carboxylate following the administration of enteral oseltamivir 75 mg twice daily in adult ECMO patients is comparable to those in ambulatory patients and far in excess of concentrations required to maximally inhibit neuraminidase activity of the H1N1 virus. Dosage adjustment for ECMO, per se, appears not to be necessary; however, doses should be reduced in patients with renal dysfunction.

For a large number of ischaemic, infective, inflammatory or traumatic conditions, hyperbaric oxygen therapy is either the only treatment or an adjunct that significantly reduces morbidity and mortality. The primary aim of this review is to identify clinical conditions treated in a paediatric population referred to Australian hyperbaric units. Secondary aims are to describe outcomes of treatment and detail any complications occurring during treatment or during transfer between units.

This was a retrospective cohort study (January 1998–December 2011) of children treated at four Australian hyperbaric medical units. A total of 112 children underwent 1099 hyperbaric treatments for 14 indications. Ages were not normally distributed with a median age of 14 years (interquartile range 11–16; range 0.25–16 years). Treatments were completed as planned in 81.5% of cases with 25 patients’ treatment terminated at the request of physicians, parents or patients. Complications relating to hyperbaric oxygen therapy occurred in 58 treatments (5.3%). Central nervous system oxygen toxicity occurred in 1:366 treatments. Our findings indicate that provision of hyperbaric oxygen therapy to children is feasible in major regional hyperbaric units and is associated with low complication rates. Management of children in an adult hyperbaric facility, however, requires significant cooperation between paediatric, intensive care and hyperbaric consultants, as the need for transfer to another hospital and prolonged transports often impacts on optimal ongoing surgical and intensive care management.

The use of epidural ropivacaine may result in significant haemodynamic fluctuations during combined epidural and general anaesthesia. We designed this study to investigate whether epidural anaesthesia with a goal-directed approach, when combined with general anaesthesia, improved haemodynamic stability in elderly patients undergoing major abdominal surgery. Seventy-five elderly patients undergoing major abdominal surgery were randomly and evenly assigned to one of three groups receiving intraoperative epidural anaesthesia with either ropivacaine 0.1% (Group 1), ropivacaine 0.375% (Group 2) or ropivacaine 0.375% for abdominal wall pain and ropivacaine 0.1% for visceral pain (Group 3). General anaesthesia was induced using a target-controlled infusion of combined propofol and remifentanil. The remifentanil target concentration was adjusted according to the mean arterial pressure and heart rate, and vasoactive agents were administered to maintain stable haemodynamics. The need for vasoactive drug administrations was 1.4 (standard deviation 0.9) in Group 3 (n=24), representing a significantly lower frequency of administration compared with Groups 1 (n=24) and 2 (n=24) (P <0.05 versus Group 1; P <0.01 versus Group 2). The total intraoperative dose of remifentanil was significantly greater in Group 1 (P <0.01 versus Group 2; P <0.05 versus Group 3) but did not differ significantly between Groups 2 and 3. Goal-directed epidural anaesthesia with different ropivacaine concentrations can improve haemodynamic stability when combined with general anaesthesia for elderly patients undergoing major abdominal surgery.

Pre-admission clinics (PAC) are now well-established in most hospitals. However, there have been few studies examining the efficacy of PACs in minimising day of surgery cancellations due to anaesthetic reasons.

A retrospective cross-sectional descriptive study was carried out in a metropolitan tertiary hospital over a four-year period to assess reasons for anaesthetic-related day of surgery cancellations in elective surgical patients who attended the PAC. Of 12,537 patients who attended the PAC during the study period, 58 (0.46%) were cancelled on the day of surgery for anaesthetic reasons. The most common cause was non-preventable misadventure such as acute respiratory tract infections, seen in 19 patients (33% of all anaesthetic cancellations). The next most common cause was classified as being due to patient or system error (16 patients). This included patients’ failure to adhere to fasting or medication guidelines, or a failure to detect and respond to abnormal laboratory results. Clinical disagreement between anaesthetic assessment at the PAC and the attending anaesthetist on the day of surgery was low (12 patients, 21%), and clinical deterioration in a pre-existing condition (six patients, 10%) accounted for the majority of other cancellations. Although patient misadventure constituted the major cause of anaesthetic cancellations, non-adherence to fasting and medication guidelines constituted the next major reason for surgery cancellation due to anaesthetic causes. This is important as such cancellations are potentially preventable and the overall cancellation rate could potentially be improved by instituting relatively simple changes to clinic function.

Emerging technologies that reduce the economic and environmental costs of anaesthesia have had limited assessment. We hypothesised that automated control of end-tidal gases, a new feature in anaesthesia machines, will consistently reduce volatile agent consumption cost and greenhouse gas emissions. As part of the planned replacement of anaesthesia machines in a tertiary hospital, we performed a prospective before and after study comparing the cost and greenhouse gas emissions of isoflurane, sevoflurane and desflurane when using manual versus automated control of end-tidal gases. We analysed 3675 general anaesthesia cases with inhalational agents: 1865 using manual control and 1810 using automated control. Volatile agent cost was $18.87/hour using manual control and $13.82/hour using automated control: mean decrease $5.05/hour (95% confidence interval: $0.88–9.22/hour, P=0.0243). The 100-year global warming potential decreased from 23.2 kg/hour of carbon dioxide equivalents to 13.0 kg/hour: mean decrease 10.2 kg/hour (95% confidence interval: 2.7–17.7 kg/hour, P=0.0179). Automated control reduced costs by 27%. Greenhouse gas emissions decreased by 44%, a greater than expected decrease facilitated by a proportional reduction in desflurane use. Automated control of end-tidal gases increases participation in low-flow anaesthesia with economic and environmental benefits.

This cross-sectional survey was designed to evaluate the current practice of anaesthetists in Australia and New Zealand with regard to aseptic technique and needle type during the performance of single-shot caudal blocks. Professional bodies suggest that full aseptic precautions be taken during the administration of caudal or epidural blocks. It has been suggested that using an intravenous cannula or a styletted needle may obviate the occurrence of epidermoid tumours. A total of 202 members of the Society for Paediatric Anaesthesia in New Zealand and Australia were invited to participate in this internet-based survey. Eighty-four responses were received. Most respondents used some form of antiseptic handwash (81%), wore sterile gloves (85.7%), used antiseptic skin preparation (100%) and draped the site (57.1%). When performing caudal blocks, 43.1% used unstyletted needles, 27.2% used styletted spinal needles and 29.6% used intravenous cannulas. However, 11.9% did not wash hands, 10.7% did not wear gloves and 42.9% did not drape the site. Three respondents reported neither handwashing, wearing gloves or draping, instead only using an alcohol swab for skin preparation. The majority of respondents in our region appear to use some level of aseptic precautions, albeit to a variable degree. Published recommendations may either be perceived as overly cautious or as ambiguous in that they do not specify caudal practice as distinct from other epidural blocks. There is a need for clearer professional guidance to support a minimum level of aseptic precaution for single-shot caudal epidural blocks.

Postintubation stenosis is the most frequent cause of benign tracheal stenosis and may cause reintubation and delay in weaning of intensive care unit patients. This case study describes typical patients with tracheal stenosis and the management of these patients. Five patients requiring reintubation and mechanical ventilation due to early intubation-related stenosis are discussed. Stridor developed in three cases after extubation. In these cases, bronchoscopy revealed tracheal stenosis. Dilatation and silicone stent placement were performed using rigid bronchoscopy. The other two patients were on ventilators when they were admitted to the intensive care unit and their stenoses were also treated by rigid bronchoscopy. Hypercapnia and hypoxia resolved after intervention in three cases. Of the remaining two patients, one had the tracheostomy closed and in the other patient ventilation was stopped but the tracheostomy was maintained. Tracheal stenosis developing in the subglottic region after extubation, especially after exposure to cuff pressure, may lead to reintubation. A tracheostomy may hinder the diagnosis of progressive stenosis and may lead to unnecessary maintenance of ventilator treatment. Early intubation-related tracheal stenosis should therefore be considered in cases of weaning or extubation failure and prompt appropriate investigation and treatment.

Pethidine (meperidine) is a unique member of the opioid family. In addition to its analgesic activity, it also has significant local anaesthetic activity. This property enables it to be used as the sole agent for spinal anaesthesia. We describe the successful use of intrathecal pethidine 1 mg/kg for an elective lower segment caesarean section in a patient presumed to be allergic to amide local anaesthetics. There were no significant adverse effects in either the mother or the newborn.

Two cases of perioperative cardiovascular collapse are presented that were associated with markedly elevated mast cell tryptase levels shortly after the event, leading to the assumption that an immunoglobin E-mediated, drug-induced anaphylaxis had occurred. However, the clinical picture in both cases was atypical and subsequent skin testing failed to identify a triggering drug. Further blood tests, some weeks later, revealed persistently elevated baseline levels of mast cell tryptase. In both cases bone marrow biopsy and genetic testing confirmed the diagnosis of mastocytosis. We present evidence and speculate that mast cell degranulation was triggered by tourniquet release in the first case and by exposure to peanuts in the second. An atypical presentation of anaphylaxis should alert the anaesthetist to the possibility of previously undiagnosed mastocytosis.

Lung protective ventilation limiting tidal volumes and airway pressures were proven to reduce mortality in patients with acute severe respiratory failure. Hypercapnia and hypercapnic acidosis is often noted with lung protective ventilation. While the protective effects of lung protective ventilation are well recognised, the role of hypercapnia and hypercapnic acidosis remains debatable. Some clinicians argue that hypercapnia and hypercapnic acidosis protect the lungs and may be associated with improved outcomes. To the contrary, some clinicians do not tolerate hypercapnic acidosis and use various techniques including extracorporeal carbon dioxide elimination to treat hypercapnia and acidosis. This review aims at defining the effects of hypercapnia and hypercapnic acidosis with a focus on the pros and cons of clearing carbon dioxide and the modalities that may enhance carbon dioxide clearance.

Predicting unexpected intensive care unit (ICU) re-admission and mortality after critical illness is difficult. This study assessed the associations between eosinopenia on the day of ICU discharge and outcomes after critical illness. This retrospective cohort study involved a total of 1446 critically ill patients who survived their first ICU admission between January 2009 and March 2010 in a multidisciplinary ICU in Western Australia. Eosinopenia was defined as eosinophil count <0.01x10⁹/l and the date of censor for survival was 31 October 2011. Of the 1446 patients included in the study, 106 patients (7.3%) were re-admitted to the ICU during the same hospitalisation and 178 patients died (12.3%) after ICU discharge. Eosinopenia at ICU discharge occurred in 130 patients (9.7%) and was more common among those who were subsequently re-admitted (18.6 vs 8.6%) or died after ICU discharge (22.5 vs 7.5%). Eosinopenia remained associated with ICU re-admission (odds ratio 2.50, 95% confidence interval 1.38–4.50; P=0.002) and post-ICU mortality (hazard ratio 2.65, 95% confidence interval 1.77–3.98; P=0.001) after adjusting for age, gender, nocturnal discharge, neutrophil count at ICU discharge, elective surgical admission, Sequential Organ Failure Assessment scores, Acute Physiology and Chronic Health Evaluation II predicted mortality and chronic medical diseases. Eosinopenia at ICU discharge explained about 8.4% of the variability and was the third most important factor in explaining the variability in survival after ICU discharge. In summary, eosinopenia at ICU discharge was associated with an increased risk of unexpected ICU re-admission and post-ICU mortality.