Anaesthesia and intensive care
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Anaesth Intensive Care · Sep 2015
Central venous-to-arterial carbon dioxide gradient as a marker of occult tissue hypoperfusion after major surgery.
The central venous-arterial carbon dioxide tension gradient ('CO₂gap') has been shown to correlate with cardiac output and tissue perfusion in septic shock. Compared to central venous oxygen saturation (SCVO2), the CO₂gap is less susceptible to the effect of hyperoxia and may be particularly useful as an adjunctive haemodynamic target in the perioperative period. This study investigated whether a high CO₂gap was associated with an increased systemic oxygen extraction (O2ER >0.3) or occult tissue hypoperfusion in 201 patients in the immediate postoperative period. ⋯ A CO₂ gap >5 mmHg had a higher sensitivity (93%) and negative predictive value (74%) than a CO₂gap >6 mmHg in excluding occult tissue hypoperfusion. Of the four variables that were predictive of an increased O₂ER in the multivariate analysis-CO₂gap, arterial pH, haemoglobin and arterial lactate concentrations-the CO₂gap (odds ratio 4.41 per mmHg increment, 95% CI 1.7 to 11.2, P=0.002) was most important and explained about 34% of the variability in the risk of occult tissue hypoperfusion. In conclusion, a normal CO₂ gap (<5 mmHg) had a high sensitivity and negative predictive value in excluding inadequate systemic oxygen delivery and may be useful as an adjunct to other haemodynamic targets in avoiding occult tissue hypoperfusion in the perioperative setting when high inspired oxygen concentrations are used.
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Anaesth Intensive Care · Sep 2015
Infraclavicular axillary vein cannulation using ultrasound in a mechanically ventilated general intensive care population.
Central venous catheter (CVC) insertion is commonly undertaken in the ICU. The use of ultrasound (US) to facilitate CVC insertion is standard and is supported by guidelines. Because the subclavian vein cannot be insonated where it underlies the clavicle, its use as a CVC site is now less common. ⋯ Thirty-nine (31%) patients had a body mass index of 30 or above, 43 (34%) patients had a coagulopathy and 70 (56%) patients had significant ventilator dependence (FiO2 of 0.5 or above, or positive end expiratory pressure 10 cmH20 or above). The technique of US-guided axillary CVC access can be undertaken successfully in ventilated intensive care patients, even in challenging circumstances. Taken together with existing work on the utility and safety of this technique, we suggest that it be adopted more widely in the intensive care population.
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Anaesth Intensive Care · Sep 2015
Factors associated with vancomycin nephrotoxicity in the critically ill.
Vancomycin is a glycopeptide antibiotic commonly used in the management of methicillin-resistant Staphylococcus aureus infection. The recent increase in prevalence of methicillin-resistant Staphylococcus aureus with reduced susceptibility to vancomycin has prompted experts to advocate for higher target trough serum concentrations. This study aimed to evaluate the potential consequences of more aggressive vancomycin therapy, by examining the association between higher serum concentrations and acute kidney injury (AKI) in a population of critically ill patients. ⋯ The median age was 57 (44 to 68) years, while the median trough serum concentration was 16 (10 to 19) mg/l. Multivariate logistic regression analysis identified mean trough concentration (OR=1.174, P=0.024), APACHE II score (OR=1.141, P=0.012) and simultaneous aminoglycoside prescription (OR=18.896, P=0.002) as significant predictors of AKI. These data suggest higher trough vancomycin serum concentrations are associated with greater odds of AKI in the critically ill.
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Anaesth Intensive Care · Sep 2015
Measurement of peak aortic jet velocity in the perioperative period-machine variability: implications for assessment of aortic stenosis severity.
Variation in echocardiography machines and probes are not well described in the perioperative period. We aimed to compare the estimation of severity of aortic stenosis with transthoracic echocardiography (TTE) using two semi-portable ultrasound machines. Experienced cardiac anaesthetists performed a limited transthoracic echocardiogram with two different semi-portable ultrasound machines in patients with known aortic stenosis. ⋯ However, the velocities obtained by the M Turbo were significantly lower than those obtained by the formal preoperative transthoracic echocardiogram (P <0.001). With the expansion of transthoracic echocardiography amongst anaesthetists, underestimation of the peak aortic jet velocity can significantly underestimate the severity of aortic stenosis with potentially lethal clinical consequences. Semi-portable ultrasound machines with echocardiographic capability are not necessarily equivalent and can result in underestimation of severity of aortic stenosis.
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In early 2015, the Medical Board of Australia commissioned research into international revalidation models and what might be applicable for Australia. This review examines the implications for Australian anaesthetists. ⋯ Although its evidence base is limited, the General Medical Council in the United Kingdom is evaluating its revalidation system, which should provide useful guidance for other countries. Australian anaesthetists and their professional organisations must remain informed about, and engaged in, the national debate about revalidation, to ensure that any new process is workable for Australian anaesthesia practice.