Anaesthesia and Intensive Care

Buprenorphine has been in clinical use in anaesthesia for several decades. Recently, the high-dose sublingual formulation (Subutex^®, Reckitt Benckiser, Slough, U.K.) has been increasingly used as maintenance therapy in opioid dependence, as an alternative to methadone and other pharmacological therapies. Buprenorphine has unique pharmacological properties making it well suited for use as a maintenance therapy in opioid dependence. However, these same properties may cause difficulty in the perioperative management of pain. Buprenorphine is a partial opioid agonist, attenuating the effects of supplemental illicit or therapeutic opioid agonists. As a result of its high receptor affinity, supplemental opioids do not readily displace buprenorphine from the opioid receptor in standard doses. High-dose buprenorphine has an extended duration of action that prolongs both of these effects.

The perioperative management of patients stabilized on high-dose buprenorphine and undergoing surgery requires consideration of the likely analgesic requirements. Where possible the buprenorphine should be continued. Pain management should focus on maximizing non-opioid analgesia, local anaesthesia and non-pharmacological techniques. Where pain may not be adequately relieved by these methods, the addition of a full opioid agonist such as fentanyl or morphine at appropriate doses should be considered, accompanied by close monitoring in a high dependency unit. In situations where this regimen is unlikely to be effective, preoperative conversion to morphine or methadone may be an option. Where available, liaison with a hospital-based alcohol and drug service should always be considered.

The risk factors for time to mortality, censored at 30 days, of patients admitted to an adult teaching hospital ICU with haematological and solid malignancies were assessed in a retrospective cohort study.

Patients, demographics and daily ICU patient data, from admission to day 8, were identified from a prospective computerized database and casenote review in consecutive admissions to ICU with haematological and solid tumours over a 10-year period (1989–99). The cohort, 108 ICU admissions in 89 patients was of mean age (±SD) 55±14 years; 43% were female. Patient diagnoses were leukaemia (35%), lymphoma (38%) and solid tumours (27%). Median time from hospital to ICU admission was five days (range 0–67). On ICU admission, 50% had septic shock and first day APACHE II score was 28±9. Forty-six per cent of patients were ventilated. ICU and 30-day mortality were 39% and 54% respectively. Multivariate Cox model predictors (P<0.05), using only ICU admission day data were: Charlson comorbidity index (CCI), time to ICU admission (days) and mechanical ventilation. For daily data (admission through day 8), predictors were: cohort effect (2nd vs 1st five-year period); CCI; time to ICU admission (days); APACHE II score and mechanical ventilation.

Outcomes were considered appropriate for severity of illness and demonstrated improvement over time. Ventilation was an independent outcome determinant. Controlling for other factors, mortality has improved over time (1st vs 2nd five year period). Analysis restricted to admission data alone may be insensitive to particular covariate effects.

This study aimed to assess the effects of dugite envenoming on blood coagulation and platelet count in a canine model, and the efficacy of fresh frozen plasma (FFP) in reversing the clotting disorder after both adequate and inadequate venom neutralization. Following initial dosing and administration studies, an intravenous venom dose of 1μg/kg was administered to eleven dogs. This was followed 30 minutes later by antivenom in either adequate or inadequate doses. A further 30 minutes later, the animals were given either two units of their own FFP or saline. Fibrinogen, aPTT and platelet levels were monitored for eight hours.

Of the six study dogs given antivenom plus FFP, two died at around 60 to 90 minutes post envenoming, at the end of the FFP infusions, and all but one of the survivors had persistent afibrinogenaemia. Of the five study dogs given antivenom and no FFP, all but one had return of detectable fibrinogen at eight hours after envenoming. The platelet count fell in all animals with recovery independent of antivenom dose, administration of FFP, or regeneration of fibrinogen. Post mortem examinations of dogs that died during dosage and administration studies showed massive intracardiac clots.

We conclude that early death from Brown Snake envenoming may be due to massive intravascular clotting. FFP administration was associated with persistent afibrinogenaemia regardless of antivenom dose. In the absence of any evidence for its efficacy, this study suggests that the role of FFP after Brown Snake envenoming should be reconsidered.

Intrathecal neostigmine has been used as an adjunct to intrathecal local anaesthetic or opioid to prolong regional analgesia and improve haemodynamic stability, with variable results. This meta-analysis aims to evaluate the effectiveness and side-effects of intrathecal neostigmine in the perioperative and peripartum settings. The literature search was based on Cochrane Controlled Trials Register, EMBASE and MEDLINE (from 1966 to 14 November 2003) databases. Volunteer and animal studies were excluded. We identified 26 studies and 19 were considered suitable for detailed data extraction. Intrathecal neostigmine increased the incidence of nausea and vomiting (OR 5.0, 95% CI: 3.4 to 7.3; P<0.00001), bradycardia requiring intravenous atropine (OR 2.7, 95% CI: 1.4 to 5.4; P=0.005), and anxiety, agitation, or restlessness (OR 10.3, 95% CI: 3.7 to 28.9; P=0.00001). It improved the overall 24 hour VAS score (–1.4 VAS pain score, 95% CI: -1.7 to -1.2, P<0.00001), delayed the time of first request for rescue analgesia (168 min, 95% CI: 125 to 211; P<0.00001), and reduced the total number of rescue injections of nonsteroidal anti-inflammatory drug within the first 24 hours (-0.8, 95% CI: -1.1 to -0.4; P=0.00001). It did not affect the duration of motor blockade (3.5 min, 95% CI: -1.5 to 8.6; P=0.17) or the total amount of ephedrine required (-0.4 mg, 95% CI: -1.5 to 0.7; P=0.5). Adding intrathecal neostigmine to other spinal medications improves perioperative and peripartum analgesia marginally when compared with placebo. It is associated with significant side-effects and the disadvantages outweigh the minor improvement in analgesia achieved.

The visual analogue scale (VAS) is a standard measurement tool in pain research and clinical practice, and has been shown to have linear scale properties for mild to moderate pain. Our aim was to evaluate the scaling properties of the VAS in subjects with severe acute pain. After Ethics Committee approval we studied 22 patients and asked them to rate the severity of their pain on a 100 mm VAS at the initial assessment (VAS₁), and again after administration of analgesic medication. The subject was asked to nominate when they considered their pain intensity had halved, and at this time they were asked to rate this on a second VAS (VAS_0.5). When the subject had received satisfactory relief of their pain, they were asked to describe how much their pain had been relieved and were then asked to rate their final pain state using a third VAS (VAS_final). The mean (SD) scores were VAS₁ 84 (14) (range 56–100), VAS_0.5 42 (13) and VAS_final 21 (16). The mean (95% CI) for VASratio was 0.51 (0.45–0.57). The mean (SD) patients’ estimate of pain relief was 77 (21)% from that of baseline, with a mean (SD) VAS_final 0.26 (0.20), 95% CI 0.17–0.38. The correlation of the patients’ estimate of pain relief with the VAS_final was r=0.89, rho=0.87, both P<0.001. The VAS is a linear scale in subjects with severe acute pain. Changes in the VAS score represent a relative change in the magnitude of pain sensation.

The cross-section of the mainstem bronchi is not completely round. For preoperative selection of a double-lumen endobronchial tube size, it may be necessary to measure the mediolateral and the anteroposterior bronchial diameters, which can be measured respectively on chest radiograph and computed tomography. With Internal Review Board approval and patients’ informed consent, 105 elective thoracic surgical patients who needed left-sided double-lumen tubes were enrolled. Double-lumen tube size was selected depending on the arithmetic mean of the mediolateral and anteroposterior bronchial diameters. Moreover, the outer diameters of the bronchial tube should be smaller than both mediolateral and anteroposterior diameters. The recommended bronchial diameter for each double-lumen tube size was chosen so that the mean of the two bronchial diameters was 0 to 2.0 mm larger than the upper limit of 95% confidence interval of the averaged outer diameter of the bronchial tube of the selected double-lumen tube. In no case was the predicted double-lumen tube size inappropriate. Generally, anteroposterior bronchial diameters appeared to be different from mediolateral diameters (P=0.001). The double-lumen tube size to be selected based on only one bronchial diameter was different from the one selected based on two perpendicularly measured bronchial diameters in 54.3% of patients (57/105). Preoperative selection of the double-lumen tube size based on the anteroposterior, mediolateral and mean bronchial diameters seems to be useful in that this may obviate the need to change an inappropriately sized double-lumen tube and may be helpful in reducing the related complications.

Intraoperative hypotension is a common and potentially deleterious event in elderly patients undergoing spinal anaesthesia for repair of hip fractures. The synergism between intrathecal opioids and local anaesthetics may allow a reduction in the dose of local anaesthetic and cause less sympathetic block and hypotension, while still maintaining adequate anaesthesia. We studied 40 elderly patients having either an insertion of a dynamic hip screw or a hemi-arthroplasty and compared 9.0 mg glucose-free bupivacaine with added fentanyl 20 μg (group BF) with 11.0 m glucose-free bupivacaine alone (group B). Hypotension was defined as a fall in systolic blood pressure to less than 75% baseline or less than 90 mmHg. The incidence and frequency of hypotension in group BF were less than in group B. Similarly, falls in systolic, diastolic and mean blood pressures were all less in group BF than in group B. However, there were four failed blocks in group BF and one in group B.

This controlled laboratory study investigated the survival of Staphylococcus epidermidis (S. epidermidis) over a 24 hour period in four commonly drawn-up anaesthetic resuscitative drugs: suxamethonium, atropine, metaraminol and ephedrine. These drugs were prepared in typical therapeutic concentrations and then inoculated with S. epidermidis. Samples of the inoculated drug preparations were cultured on horse blood agar plates at 0, 2, 6, 12 and 24 hourly intervals and incubated for 24 hours.

Colony counts were performed at the end of the incubation period. Suxamethonium, atropine and metaraminol all showed an inhibitory effect on colony counts within the first six hours. There was a more gradual decline of colony counts over a 24 hour period in the ephedrine solution. This decline was similar to that occurring in the normal saline. It is concluded that suxamethonium, atropine and metaraminol do not support the survival of the common skin contaminant, S. epidermidis over a 24 hour period.

The purpose for this study was to examine the efficacy of patient-controlled sedation (PCS) with remifentanil as an intravenous adjunct to local anaesthesia for treating pain associated with dental extraction during monitored anaesthetic care. Forty ASA 1–2 and aged 18 or older Chinese patients presenting for third molar extraction on an outpatient basis were randomly assigned to either remifentanil (RG; n=20) or saline groups (CG; n=20). All patients completed the study. Patients in the RG and CG were comparable in terms of demographic variables, PCS demands and PCS boluses. There was high variability of PCS among patients in both groups in terms of demands (range for RG 0–62; CG 0–41) and consumption (range for RG 0–26; CG 0–13). Neither group required any rescue local anaesthetic injection for pain or midazolam for anxiety. There was no clinically relevant differences in outcome measures (pain scores, anxiety scores, systolic and diastolic blood pressures, heart rate, and SpO₂) between the two groups. There were no other major complications such as apnoea, desaturation, bradycardia, or chest wall rigidity in either group. We conclude that, although it appeared to be safe, the addition of patient-controlled remifentanil was not a useful adjunct to local anaesthesia for pain associated with third molar dental extraction.

We have previously found evidence of contaminants in 0.9% saline packaged in polyvinyl chloride (PVC) for clinical use. For this current study we asked two questions: (1) what are the organic chemical contaminants in solutions packaged in PVC? and (2) do the contaminants vary in bags manufactured in different countries? We studied samples of 0.9% saline packaged in PVC from Australasia, Europe, and North America. We analysed the saline solutions with high-resolution capillary gas chromatography – mass spectrometry. Components of the Australasian and European bags were also analysed using thermodesorption followed by gas chromatography and mass spectrometry. In three pairs of samples we found twenty-four different organic contaminants of the saline solutions. Diethylhexyl phthalate (DEHP) was found in all solutions; the concentrations were greater than 10 μg/l in the Australasian and European samples. All samples contained 2-ethyl hexanol (>50 μg/l), a DEHP breakdown product. The Australasian and North American samples contained cyclohexanone at concentrations of about 1000 μg/l. The cyclohexanone probably originated in joints at the bases of the bags. Both the Australasian and European bags contained t-butyl cyclohexanol (>500 μg/l) and t-butyl cyclohexanone (>50 μg/l). Printing ink on the outside of the bags was the most likely source for both of these contaminants. Several of the contaminants are toxic to animals. Little is known about the toxicity of combinations of contaminants.

This prospective clinical investigation assessed the effect of placement of a Univent^® tube on the anatomy of the internal jugular veins and the success of cannulation of the left internal jugular vein. After obtaining informed consent, 48 adult patients were enrolled. Of these, 42 patients were eligible and were divided into two groups: Univent^® tube (group U, n=21) and wire enforced endotracheal tube (group C, n=21). The Univent^® tube group were having a left thoracotomy. Using horizontal ultrasound scans just above the thyroid gland, the internal jugular vein was visualized and measured before and after Univent^® placement. The number of needle passes necessary to cannulate the left internal jugular vein in the two groups was also compared.

Univent^® tubes were associated with lateral displacement of the right carotid artery and internal jugular vein on the convex side of the Univent^® tube, with compression of the right internal jugular vein by the artery, resulting in a kidney-shaped cross-section of the vein. On the left (concave side of the tube), the neck was indented, the sheath of the left carotid artery was displaced medially, and the left internal jugular vein distorted to an ellipse. There was a significant increase in the lateral diameter and a decrease in the cross-sectional area of the left internal jugular vein (t-test, P<0.05). The first attempt at cannulation of the left internal jugular vein failed significantly more often in the Univent^® group (13/21 vs 5/21 in group C, Chi-square 6.22, P=0.025). Cannulation of the internal jugular vein before placement of the Univent^® tube, or placement with ultrasound guidance is suggested.

This study of ventilated patients investigated current clinical practice in 476 episodes of pneumonia (48% community-acquired pneumonia, 24% hospital-acquired pneumonia, 28% ventilator-associated pneumonia) using a prospective survey in 14 intensive care units (ICUs) within Australia and New Zealand. Diagnostic methods and confidence, disease severity, microbiology and antibiotic use were assessed.

All pneumonia types had similar mortality (community-acquired pneumonia 33%, hospital-acquired pneumonia 37% and ventilator-associated pneumonia 24%, P=0.15) with no inter-hospital differences (P=0.08–0.91). Bronchoscopy was performed in 26%, its use predicted by admission hospital (one tertiary: OR 9.98, CI 95% 5.11–19.49, P<0.001; one regional: OR 6.29, CI 95% 3.24–12.20, P<0.001), clinical signs of consolidation (OR 3.72, CI 95% 2.09–6.62, P<0.001) and diagnostic confidence (OR 2.19, CI 95% 1.29–3.72, P=0.004). Bronchoscopy did not predict outcome (P=0.11) or appropriate antibiotic selection (P=0.69). Inappropriate antibiotic prescription was similar for all pneumonia types (11–13%, P=0.12) and hospitals (0–16%, P=0.25). Blood cultures were taken in 51% of cases. For community-acquired pneumonia, 70% received a third generation cephalosporin and 65% a macrolide. Third generation cephalosporins were less frequently used for mild infections (OR 0.38, CI 95% 0.16–0.90, P=0.03), hospital-acquired pneumonia (OR 0.40, CI 95% 0.23–0.72, P<0.01), ventilator-associated pneumonia (OR 0.04, CI 95% 0.02–0.13, P<0.001), suspected aspiration (OR 0.20, CI 95% 0.04–0.92, P=0.04), in one regional (OR 0.26, CI 95% 0.07–0.97, P=0.05) and one tertiary hospital (OR 0.14, CI 95% 0.03–0.73, P=0.02) but were more commonly used in older patients (OR 1.02, CI 95% 1.01–1.03, P=0.01).

There is practice variability in bronchoscopy and antibiotic use for pneumonia in Australian and New Zealand ICUs without significant impact on patient outcome, as the prevalence of inappropriate antibiotic prescription is low. There are opportunities for improving microbiological diagnostic work-up for isolation of aetiological pathogens.

This study of ventilated patients investigated pneumonia risk factors and outcome predictors in 476 episodes of pneumonia (48% community-acquired pneumonia, 24% hospital-acquired pneumonia, 28% ventilator-associated pneumonia) using a prospective survey in 14 intensive care units within Australia and New Zealand. For community acquired pneumonia, mortality increased with immunosuppression (OR 5.32, CI 95% 1.58–17.99, P<0.01), clinical signs of consolidation (OR 2.43, CI 95% 1.09–5.44, P=0.03) and Sepsis-Related Organ Failure Assessment (SOFA) scores (OR 1.19, CI 95% 1.08–1.30, P<0.001) but improved if appropriate antibiotic changes were made within three days of intensive care unit admission (OR 0.42, CI 95% 0.20–0.86, P=0.02). For hospital-acquired pneumonia, immunosuppression (OR 6.98, CI 95% 1.16–42.2, P=0.03) and non-metastatic cancer (OR 3.78, CI 95% 1.20–11.93, P=0.02) were the principal mortality predictors. Alcoholism (OR 7.80, CI 95% 1.20–17.50, P<0.001), high SOFA scores (OR 1.44, CI 95% 1.20–1.75, P=0.001) and the isolation of “high risk” organisms including Pseudomonas aeruginosa, Acinetobacter spp, Stenotrophomonas spp and methicillin resistant Staphylococcus aureus (OR 4.79, CI 95% 1.43–16.03, P=0.01), were associated with increased mortality in ventilator-associated pneumonia. The use of non-invasive ventilation was independently protective against mortality for patients with community-acquired and hospital-acquired pneumonia (OR 0.35, CI 95% 0.18–0.68, P=0.002). Mortality was similar for patients requiring both invasive and non-invasive ventilation and non-invasive ventilation alone (21% compared with 20% respectively, P=0.56).

Pneumonia risks and mortality predictors in Australian and New Zealand ICUs vary with pneumonia type. A history of alcoholism is a major risk factor for mortality in ventilator-associated pneumonia, greater in magnitude than the mortality effect of immunosuppression in hospital-acquired pneumonia or community-acquired pneumonia. Non-invasive ventilation is associated with reduced ICU mortality. Clinical signs of consolidation worsen, while rationalising antibiotic therapy within three days of ICU admission improves mortality for community-acquired pneumonia patients.

The manner in which elements of clinical history, physical examination and investigations influence subjectively assessed illness severity and outcome prediction is poorly understood. This study investigates the relationship between clinician and objectively assessed illness severity and the factors influencing clinician's diagnostic confidence and illness severity rating for ventilated patients with suspected pneumonia in the intensive care unit (ICU).

A prospective study of fourteen ICUs included all ventilated admissions with a clinical diagnosis of pneumonia. Data collection included pneumonia type – community-acquired (CAP), hospital-acquired (HAP) and ventilator-associated (VAP), clinician determined illness severity (CDIS), diagnostic methods, clinical diagnostic confidence (CDC), microbiological isolates and antibiotic use.

For 476 episodes of pneumonia (48% CAP, 24% HAP, 28% VAP), CDC was greatest for CAP (64% CAP, 50% HAP and 49% VAP, P<0.01) or when pneumonia was considered “life-threatening” (84% high CDC, 13% medium CDC and 3% low CDC, P<0.001). “Life-threatening” pneumonia was predicted by worsening gas exchange (OR 4.8, CI 95% 2.3–10.2, P<0.001), clinical signs of consolidation (OR 2.0, CI 95% 1.2–3.2, P<0.01) and the Sepsis-Related Organ Failure Assessment (SOFA) Score (OR 1.1, CI 95% 1.1–1.2, P<0.001). Diagnostic confidence increased with CDIS (OR 16.3, CI 95% 8.4–31.4, P<0.001), definite pathogen isolation (OR 3.3, CI 95% 2.0–5.6) and clinical signs of consolidation (OR 2.1, CI 95% 1.3–3.3, P=0.001). Although the CDIS, SOFA Score and the Simplified Acute Physiologic Score (SAPS II) were all associated with mortality, the SAPS II Score was the best predictor of mortality (P=0.02).

Diagnostic confidence for pneumonia is moderate but increases with more classical presentations. A small set of clinical parameters influence subjective assessment. Objective assessment using SAPS II Scoring is a better predictor of mortality.

A 45-year-old woman presented to the emergency department of a tertiary referral hospital after taking an overdose of verapamil, doxepin, quetiapine, diazepam, temazepam, and clonazepam. She rapidly developed shock refractory to pharmacological support and was placed on percutaneous venoarterial extracorporeal membrane oxygenation (ECMO). She had a severe metabolic acidosis from a combination of shock and drug intoxication that improved with continuous venovenous haemodialysis. Forty-eight hours after presentation, while still on ECMO, the patient had complete cardiac standstill for three and a half hours, attributable to slow-release verapamil, that resolved after the commencement of plasmapheresis. The role of plasmapheresis in verapamil overdose requires further study.

A 50-year-old male presented for a Whipple's procedure to excise a pancreatic lesion. Massive transfusion of packed cells and fresh frozen plasma was required. Towards the end of the procedure, the patient developed sudden onset of frank pulmonary oedema and hypotension. A presumptive diagnosis of transfusion related lung injury was made after prompt investigations excluded circulatory overload or cardiogenic shock as the cause. This case report describes an increasingly common and life-threatening sequela of blood product transfusion, the management of which is complicated by the current lack of specific diagnostic tests.

A 72-year-old female underwent elective lumbar spinal decompression. At the end of the procedure an epidural catheter was sited by the surgeon under direct vision. A bolus of levobupivacaine was injected. Shortly after reaching the recovery area, the patient collapsed and required re-intubation and mechanical ventilation. She was extubated five hours later and suffered no adverse sequelae. Having excluded other possible causes of immediate post-operative collapse, a clinical diagnosis of subdural blockade was made.

A literature search using Medline has found no other case reports of such a complication following epidural placement under direct vision.

Castleman's disease is a lymphoreticular disorder, often localized and clinically silent. Systemic manifestations may occur. Castleman's disease may be associated with pathologies such as POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes), AIDS, amyloidosis, pemphigus vulgaris, and other types of cancer such as lymphoma and Kaposi's sarcoma. Careful preoperative evaluation is required to determine whether associated mediastinal or spinal canal masses or haematological disorders are present. The significance of these pathologies for anaesthetic management is discussed.

We present the case of a 27-year-old female patient with Castleman's disease (hyaline-vascular variant) requiring vaginal reconstruction due to recurrent sores and synechiae.