Anaesthesia and Intensive Care

There is no uniformly accepted protocol for the radiological assessment of the cervical spine in critically ill trauma patients. The Alfred Trauma Centre receives about 40% of Victorian patients with major trauma. A protocol was developed for cervical spine evaluation, comprising three plain X-rays and a swimmer's view added when necessary to visualize C7-T1, CT and/or MRI for abnormal regions, and functional (flexion/extension) X-rays to exclude cervical spine instability due to soft tissue trauma. Functional X-rays were performed “actively” in conscious patients and “passively” in unconscious patients. One hundred consecutive patients were prospectively evaluated and 91 survived to complete data collection. Six (6.6%) had unstable cervical spine injuries—five detected with plain X-rays and one (1.1%) detected only with passive functional X-rays. Static cervical X-rays cost $93.00 per patient. Functional cervical X-rays added $42.00 per patient and were uncomplicated. Collar complications were common when collars remained on for more than 72 hours. This low detection rate is clinically important because of the enormous potential social and economic costs of missed unstable cervical spine fractures.

This study questioned whether manual lung hyperinflation (MHI) and postural drainage reduced the incidence of nosocomial pneumonia or improved other outcome variables in mechanically ventilated trauma patients. Patients were withdrawn from the study if they developed nosocomial pneumonia according to a predetermined definition or on the clinical suspicion of nosocomial pneumonia by the attending intensivist.

Of the 46 patients who fulfilled all the inclusion criteria and were enrolled into the study, 22 patients were randomized to group A (physiotherapy) and 24 patients to group B (control group). Twice as many patients were withdrawn in group B (8/24) compared with group A (4/22), although the differences were not statistically significant, [X²(1, 1) = 1.36, P = 0.24]. The length of time receiving mechanical ventilation and in the ICU was similar between the two groups and there were no differences in pulmonary dysfunction (“worst” daily P_aO₂/FiO₂ ratio) between the two groups. There were no ICU deaths in either group.

Physiotherapy as used in this study was not associated with a reduced incidence of nosocomial pneumonia based on standard clinical criteria. Nevertheless the trend to more frequent nosocomial pneumonia in the control patients suggests that a larger study in more severely injured patients with stricter clinical criteria for the definition of nosocomial pneumonia is indicated.

We aimed to compare the efficacy of fluid preloading with two recently recommended fluid-vasopressor regimens for maintaining blood pressure during subarachnoid anaesthesia in the elderly. Sixty elderly patients requiring surgery for traumatic hip fractures received subarachnoid anaesthesia using 0.05 ml/kg of 0.5% heavy bupivacaine. Hypotension, i.e. systolic arterial pressure <75% of baseline, was prevented or treated by: A—normal saline 16 ml/kg plus intravenous ephedrine boluses (0.1 mg/kg); B—normal saline 8 ml/kg plus intramuscular depot ephedrine (0.5 mg/kg); or C—Haemaccel 8 ml/kg plus metaraminol infusion. Systolic arterial pressure and heart rate were recorded using custom-written computer software (Monitor, version 1.0).

Systolic arterial pressure decreased in all groups after five minutes (P<0.001). Decreases were greatest in group A (P<0.05). Heart rate increased by 7% group A and decreased by 9% in group C (P<0.05). During the first hour, hypotension was present for 47%, 25% and 20% of the time in groups A, B and C respectively and overcorrection of systolic arterial pressure occurred in 19% of the time in group C.

We conclude that treatment A was inadequate in preventing hypotension. Treatments B and C were more effective but were associated with an increased heart rate and overcorrection of systolic arterial pressure respectively.

The effect of low-dose heparin on postoperative hypercoagulability was assessed using thrombelastography (TEG) in eighteen patients undergoing elective abdominal aortic surgery. Patients received unfractionated heparin 50001U bd SC commencing on the first postoperative day. Native whole blood TEG was performed preoperatively and on day two postoperatively. A heparinase-modified TEG was performed at the same time as the native whole blood TEG on day two. There were no significant changes in the postoperative native whole blood TEG variables (r, K, α, MA) relative to preoperative controls. In contrast, there were significant decreases in r and K, and increases in a in the heparinase-modified TEGs postoperatively (P<0.01). There were significant differences between the postoperative native whole blood and heparinase-modified TEGs for all TEG variables (P<0.01). The results indicate that low-dose heparin reduces postoperative hypercoagulability following abdominal aortic surgery as assessed by thrombelastography.

A phase 2, single-blinded, randomized, multicentre trial was conducted to compare recovery times from anaesthesia between patients induced with a new short-acting benzodiazepine Ro 48-6791 (Hoffman-La Roche, Sydney, N.S. W.) or propofol. Seventy-six patients were randomly allocated to receive either Ro 48-6791 or propofol for induction followed by a standardized anaesthetic. Alertness and ambulatory function during recovery were scored by a rater blinded to treatment group. Mean time to awakening was longer for the Ro 48-6791 group (15 min), compared with propofol (7 min, P<0.001), as was mean time to full clinical recovery (116 min vs 75 min respectively, P=0.002). Both groups showed similar cardiovascular stability following induction, but shorter apnoea times were demonstrated for Ro 48-6791 (48s vs 133, P<0.001). The longer recovery times with Ro 48-6791 would make this drug a less suitable sole induction agent than propofol for routine use in day stay surgery. Further studies of Ro 48-6791 should pay particular attention to the effect of dose reduction on recovery profile.

The purpose of this study was to compare the use of 0.5% ropivacaine with 0.5% bupivacaine for axillary brachial plexus anaesthesia.

Sixty-six patients undergoing upper limb surgery were enrolled in a double-blind, randomized, multicentre trial. Five patients were subsequently excluded for various reasons. Of the remaining patients, 30 received 40 ml of 0.5%) ropivacaine and 31 received 40 ml of 0.5% bupivacaine. Brachial plexus block was performed by the axillary approach using a standardized technique with a peripheral nerve stimulator. Parameters investigated included the frequency, onset and duration of sensory and motor block, the quality of anaesthesia and the occurrence of any adverse events.

The six principal nerves of the brachial plexus were studied individually. The frequency for achieving anaesthesia per nerve ranged from 70 to 90% in the ropivacaine group and 81 to 87% in the bupivacaine group. The median onset time for anaesthesia was 10 to 20 minutes with ropivacaine and 10 to 30 minutes with bupivacaine, and the median duration was 5.3 to 8.7h with ropivacaine and 6.9 to 20.3h with bupivacaine. Motor block was evaluated at the elbow, wrist and hand, and was completely achieved at a rate of 60 to 73% in the ropivacaine group and 55 to 71% in the bupivacaine group. The median duration of motor block was 6.5 to 7.5h with ropivacaine and 6.0 to 9.0h with bupivacaine. These parameters were not statistically different. The duration of partial motor block at the wrist (6.8 v 16.4h) and hand (6.7 v 12.3h) was significantly longer with bupivacaine.

Ropivacaine 0.5% and bupivacaine 0.5%) appeared equally efficacious as long-acting local anaesthetics for axillary brachial plexus block.

Suxamethonium in the doses of 1.0, 0.5 and 0.25 mg/kg was compared with mivacurium 0.15 mg/kg in 80 patients requiring nasotracheal intubation for maxillofacial surgery in a double-blind randomized controlled trial. Anaesthesia was induced with thiopentone 5 mg/kg and alfentanil 15 μg/kg. Patients were randomly allocated to one of the four relaxant groups. Anaesthesia was maintained with enflurane in 70% nitrous oxide and 30% oxygen and analgesia provided with intravenous pethidine 0.5 to 1.5 mg/kg and rectal indomethacin 100mg. All patients given mivacurium or suxamethonium 1mg/kg had acceptable intubating conditions. Significantly fewer patients given suxamethonium 0.5 mg or 0.25 mg/kg had acceptable intubating conditions (90% and 70% respectively) (P=0.003). Poor intubating conditions requiring additional relaxation were seen in two patients given suxamethonium 0.25 mg/kg and two given 0.5 mg/kg, while no patients given suxamethonium 1.0 mg/kg or mivacurium 0.15 mg/kg required additional relaxation (P=0.004). Only four patients had postoperative myalgia, all of whom were given suxamethonium 0.5 mg/kg or more but no significant difference between groups could be demonstrated.

We have compared the performance of a standard T-piece, a Venturi T-piece and a T-bag (T-piece with a small reservoir bag) for emergence with the laryngeal mask airway in 20 awake volunteers. FiO₂, ETCO₂ and FiCO₂ were measured at oxygen flow rates of 2, 4 and 6 l.min^-1 during three different breathing patterns: normal tidal volume, respiratory rate 12 .min^-1; normal tidal volume, respiratory rate 20 .min^-1; high tidal volume, respirutory rate 12 .min^-1. The T-piece and T-bag delivered a higher overall average FiO₂ than the Venturi T-piece (P<0.00001). Compared with normal breathing, FiO₂ was reduced at the higher respiratory rate and tidal volume with the T-piece and T-bag hut was not reduced with the Venturi T-piece. FiO₂ increased with increasing flow rates for all devices except the Venturi T-piece during normal breathing. ETCO₂ was higher during normal breathing (4.4±0.0%) compared with higher respiratory rate (3.7±0.9%) and tidal volume (3.4±0.7%) for all devices. There were no differences in overall ETCO₂ between devices. The FiCO₂ was never higher than 0.2% in any subject. We conclude that the T-piece and T-bag are more effective oxygen enrichment devices than the Venturi T-piece. The T-bag provides a useful visual signal about depth and frequency of respiration.

The cardiovascular, coagulation and haematological effects of Tiger Snake (Notechis scutatus) venom were investigated in anaesthetized, mechanically ventilated dogs. Intravenous infusion of venom caused dose-related systemic hypotension, low cardiac output, pulmonary hypertension and raised pulmonary artery occlusion pressure. These effects occurred within several minutes of venom administration but recovered over 30 to 40 minutes. They were accompanied by prolongation of prothrombin and activated partial thromboplastin times and by depletion of serum fibrinogen. Fibrin degradation products were not detected. Thrombocytopenia and leucopenia were observed within minutes of venom administration but recovered over 30 to 40 minutes. The mechanism of systemic hypotension is probably pulmonary vascular obstruction and coronary ischaemia caused by disseminated intravascular coagulation, although the existence of a myocardial depressant in venom or release of vasoactive substances by venom cannot be excluded.

This case report details spinal anaesthesia for an elective caesarean section in a patient with the rare condition of paramyotonia congenita. There are few case reports of anaesthesia in this condition and none in the Australian anaesthetic literature. This case highlights the need for the avoidance of hypothermia and depolarizing muscle relaxants, the safety of spinal anaesthesia and a conservative approach to the management of plasma potassium concentration. The subsequent review outlines the current literature and discusses other issues involved in the anaesthetic management of this disorder.

Near-infrared spectroscopy is a technique used for non-invasive measurement of cerebral oxygenation and a number of commercial devices are currently available for use. We compared measurements of cerebral oxygenation made with two near-infrared spectrophotometers—the Somanetics Invos 3100 cerebral oximeter and the Hamamatsu NIRO-500 near-infrared spectrophotometer. Hypoxia was induced in six healthy male volunteers with and without occlusion of scalp blood flow. Oxygen saturation, end-tidal carbon dioxide tension, regional cerebral oxygen saturation, change in regional cerebral oxyhaemoglobin concentration and change in regional cerebral total haemoglobin concentration were measured. The INVOS 3100 displays cerebral oxygen saturation directly. The NIRO-500 displays change in total haemoglobin concentration and oxyhaemoglobin concentration, and the cerebral oxygen saturation was calculated offline. Statistical analysis disproved the assumption that the INVOS 3100 and the NIRO-500 were measuring the same changes in cerebral oxygenation. Neither machine can be confirmed for reliability against a gold standard and operational difficulties mean that neither can be recommended for routine clinical use.

A study was undertaken to assess the performance of the Komesaroff vaporizer, placed within the circuit, in ventilated patients during maintenance of closed circuit anaesthesia with halothane or isoflurane. Following intravenous induction, anaesthesia was maintained by inhalation. This was achieved using a conventional vaporizer outside the circle for the first 10 minutes to manage the fast uptake phase. The fresh gas flow was then reduced to the basal oxygen requirement with the Komesaroff vaporizer within the circle maintaining inhalational anaesthesia. Complete isolation of the circuit was achieved by returning all anaesthetic gases to the circuit following analysis and using a bag-in-bottle ventilator. The Komesaroff vaporizer dial was positioned at between the first and second division and end-tidal volatile anaesthetic agent levels were measured. This study demonstrated that at dial positions I or 1.5 with either agent, the end-tidal volatile concentration plateaued at clinically acceptable levels. The Komesaroff vaporizer can therefore be used safely in ventilated patients to maintain closed circuit anaesthesia provided clinical observation and monitoring are meticulous.

A survey of all registered obstetrician/gynaecologists in Western Australia (n = 79) was conducted to obtain information regarding their level of knowledge about epidural analgesia (EA) in labour and its complications, their sources of information about EA, and their opinions regarding its role in labour and effect on progress of labour. Response rate was 68%.

Most respondents had only received lectures about EA after specialist training and 20% did not achieve an adequate knowledge score. Those of less than five years’ experience achieved significantly better scores.

Over a third did not favour EA in labour until active labour was established, though 90% would recommend it by late first stage in those with a potentially complicated delivery. For women with cardiac or significant medical disease aggravated by labour, 18% would wait until the late first or second stage before suggesting EA. Seventy-seven per cent believed EA prolonged the second stage of labour, though opinion varied regarding EA effects on the duration and progress of first and third stages.

Up to thirty minutes delay before epidural placement is acceptable to 87%. This survey suggests that there is both a demand and a need for greater education about EA in labour, particularly with respect to EA side-effects, complications and effects on labour, in the subgroup of obstetricians who have been in obstetric practice more than five years.

With the growing quest for answers to vexing dilemmas in critically ill patients, more intensive care units are embarking on clinical research. This places increasing importance on Good Clinical Research Practice (GCRP), a set of guidelines drawn up by the Pharmaceutical Industry to assist investigators in conducting ethical, reliable scientific studies. GCRP is a combination of good basic management skills allied to ethical principles for scientific research. Based on the principles of the Declaration of Helsinki, it consists of three tenets: patient protection (ethics), credible data (science) and data control. This article describes GCRP specifically relating it to the intensive care situation, illustrating some of the concepts with practical examples. With a minimum of extra time and effort these basic-principles can be integrated as routine into all research projects.

A case of hepatic portal venous gas following intestinal ileus in a critically ill patient in the intensive care unit, who went on to have a successful outcome, is described. Although hepatic portal venous gas (HPVG) is usually associated with an abdominal catastrophe and portends a poor clinical outcome, there are a number of benign causes of HPVG. The pathophysiological processes such as gut bacterial translocation and altered intestinal permeability that may occur as a paraphenomenon in the setting of HPVG are discussed.

The obstruction of an endotracheal tube with the patient in the prone position creates major anaesthetic difficulties that may result in patient morbidity and mortality. We describe a case involving the clearing of a blocked endotracheal tube with an arterial embolectomy catheter and discuss the relevance to anaesthetic practice.

A 23-year-old primigravida with Lemierre's syndrome developed pericardial tamponade secondary to mediastinal infection and anticoagulant therapy. Intrathoracic echocardiographic diagnosis during a period of cardiac arrest led to urgent pericardiocentesis and successful resuscitation.

A 68 year-old-man presented some twelve hours after a presumed Tiger Snake bite with coagulopathy, paralysis and muscle necrosis. He suffered multi-system failure requiring prolonged ventilation, haemodialysis and supportive care, to be discharged after 26 days. Delays to antivenom therapy after tiger snake envenomation can result in significant morbidity. Australian snakes are the most venomous in the world.

Maffucci's syndrome is a rare, congenital disease due to neuro-ectodermal dysplasia and is characterized by enchondromatosis and multiple soft tissue haemangiomata. A case of Maffucci's syndrome with haemangiomata along the upper airways requiring laser surgery is described. The literature on Maffucci's syndrome is reviewed.