Adjacent central venous catheters can result in immediate aspiration of infused drugs during renal replacement therapy.

Anaesthesia. 2012 Feb;67(2):115-21

Authors: Kam KY, Mari JM, Wigmore TJ

Abstract
Dual-lumen haemodiafiltration catheters enable continuous renal replacement therapy in the critically ill and are often co-located with central venous catheters used to infuse drugs. The extent to which infusions are immediately aspirated by an adjacent haemodiafiltration catheter remains unknown. A bench model was constructed to evaluate this effect. A central venous catheter and a haemodiafiltration catheter were inserted into a simulated central vein and flow generated using centrifugal pumps within the simulated vein and haemodiafiltration circuit. Ink was used as a visual tracer and creatinine solution as a quantifiable tracer. Tracers were completely aspirated by the haemodiafiltration catheter unless the infusion was at least 1 cm downstream to the arterial port. No tracer was aspirated from catheters infusing at least 2 cm downstream. Orientation of side ports did not affect tracer elimination. Co-location of central venous and haemodiafiltration catheters may lead to complete aspiration of infusions into the haemodiafilter with resultant drug under-dosing.

PMID: 22059378 [PubMed - indexed for MEDLINE]

The influence of clinical risk factors on pre-operative B-type natriuretic peptide risk stratification of vascular surgical patients.

Anaesthesia. 2012 Jan;67(1):55-9

Authors: Biccard BM, Lurati Buse GA, Burkhart C, Cuthbertson BH, Filipovic M, Gibson SC, Mahla E, Leibowitz DW, Rodseth RN

Abstract
The role of the revised cardiac risk index in risk stratification has recently been challenged by studies reporting on the superior predictive ability of pre-operative B-type natriuretic peptides. We found that in 850 vascular surgical patients initially risk stratified using B-type natriuretic peptides, reclassification with the number of revised cardiac risk index risk factors worsened risk stratification (p?<?0.05 for >?0, >?2, >?3 and >?4 risk factors, and p?=?0.23 for >?1 risk factor). When evaluated with pre-operative B-type natriuretic peptides, none of the revised cardiac risk index risk factors were independent predictors of major adverse cardiac events in vascular patients. The only independent predictor was B-type natriuretic peptide stratification (OR 5.1, 95% CI 1.8-15 for the intermediate class, and OR 25, 95% CI 8.7-70 for the high-risk class). The clinical risk factors in the revised cardiac risk index cannot improve a risk stratification model based on B-type natriuretic peptides.

PMID: 22059440 [PubMed - indexed for MEDLINE]

Complications associated with peripheral or central routes for central venous cannulation.

Anaesthesia. 2012 Jan;67(1):65-71

Authors: Pikwer A, Åkeson J, Lindgren S

Abstract
We undertook a review of studies comparing complications of centrally or peripherally inserted central venous catheters. Twelve studies were included. Catheter tip malpositioning (9.3% vs 3.4%, p = 0.0007), thrombophlebitis (78 vs 7.5 per 10,000 indwelling days, p = 0.0001) and catheter dysfunction (78 vs 14 per 10,000 indwelling days, p = 0.04) were more common with peripherally inserted catheters than with central catheter placement, respectively. There was no difference in infection rates. We found that the risks of tip malpositioning, thrombophlebitis and catheter dysfunction favour clinical use of centrally placed catheters instead of peripherally inserted central catheters, and that the two catheter types do not differ with respect to catheter-related infection rates.

PMID: 21972789 [PubMed - indexed for MEDLINE]

Subclavian cannulation with ultrasound: a novel method.

Anaesthesia. 2010 Oct;65(10):1041

Authors: Vassallo JM, Bennett MJ

PMID: 21198469 [PubMed - indexed for MEDLINE]

Hypertonic saline in critical care: a review of the literature and guidelines for use in hypotensive states and raised intracranial pressure.

Anaesthesia. 2009 Sep;64(9):990-1003

Authors: Strandvik GF

Hypertonic saline has been in clinical use for many decades. Its osmotic and volume-expanding properties make it theoretically useful for a number of indications in critical care. This literature review evaluates the use of hypertonic saline in critical care. The putative mechanism of action is presented, followed by a narrative review of its clinical usefulness in critical care. The review was conducted using the Scottish Intercollegiate Guidelines Network method for the review of cohort studies, randomised-controlled trials and meta-analyses. The review focuses specifically on blood pressure restoration and outcome benefit in both haemorrhagic and non-haemorrhagic shock, and the management of raised intracranial pressure. Issues of clinical improvement and outcome benefit are addressed. Hypertonic saline solutions are effective for blood pressure restoration in haemorrhagic, but not other, types of shock. There is no survival benefit with the use of hypertonic saline solutions in shock. Hypertonic saline solutions are effective at reducing intracranial pressure in conditions causing acute intracranial hypertension. There is no survival or outcome benefit with the use of hypertonic saline solutions for raised intracranial pressure. Recommendations for clinical use and future directions of clinical research are presented.

PMID: 19686485 [PubMed - indexed for MEDLINE]

Modelling the impact of an influenza A/H1N1 pandemic on critical care demand from early pathogenicity data: the case for sentinel reporting.

Anaesthesia. 2009 Sep;64(9):937-41

Authors: Ercole A, Taylor BL, Rhodes A, Menon DK

Projected critical care demand for pandemic influenza H1N1 in England was estimated in this study. The effect of varying hospital admission rates under statistical uncertainty was examined. Early in a pandemic, uncertainty in epidemiological parameters leads to a wide range of credible scenarios, with projected demand ranging from insignificant to overwhelming. However, even small changes to input assumptions make the major incident scenario increasingly likely. Before any cases are admitted to hospital, 95% confidence limit on admission rates led to a range in predicted peak critical care bed occupancy of between 0% and 37% of total critical care bed capacity, half of these cases requiring ventilatory support. For hospital admission rates above 0.25%, critical care bed availability would be exceeded. Further, only 10% of critical care beds in England are in specialist paediatric units, but best estimates suggest that 30% of patients requiring critical care will be children. Paediatric intensive care facilities are likely to be quickly exhausted and suggest that older children should be managed in adult critical care units to allow resource optimisation. Crucially this study highlights the need for sentinel reporting and real-time modelling to guide rational decision making.

PMID: 19645759 [PubMed - indexed for MEDLINE]

B type natriuretic peptide--a diagnostic breakthrough in peri-operative cardiac risk assessment?

Anaesthesia. 2009 Feb;64(2):165-78

Authors: Rodseth RN

The B-type natriuretic peptides; B-type natriuretic peptide and N-terminal pro-B-type natriuretic peptide, are increasing being used as biomarkers for the diagnosis, management and prognostication of cardiac failure, but their application in the peri-operative period is unclear. This review examines the current understanding of the role of B-type natriuretic peptides in both the operative and non-operative settings. Normal values, diagnostic thresholds, monitoring targets and significant prognostic levels are identified. Using this as a background, the role of B-type natriuretic peptides in the prediction of peri-operative mortality and morbidity is examined and potential confounders, such as renal failure and body mass index, which may impact significantly on the utility of the biomarkers, are discussed. Clinical recommendations with regard to its use are made and a research agenda is proposed for future peri-operative studies.

PMID: 19143695 [PubMed - indexed for MEDLINE]

A survey of the use of ultrasound guidance in internal jugular venous cannulation.

Anaesthesia. 2008 Nov;63(11):1222-5

Authors: McGrattan T, Duffty J, Green JS, O'Donnell N

It has been that suggested the use of two dimensional (2D) ultrasound to facilitate placement of central venous cannulae in the internal jugular vein improves patient safety and reduces complications. Since the introduction of the National Institute for Clinical Excellence Technology Appraisal Guideline Number 49 in 2002, promoting the use of ultrasound in placement of internal jugular venous cannulae, utilisation of ultrasound has increased throughout the United Kingdom. We report the findings of a postal survey of 2000 senior anaesthetists in the United Kingdom which enquired about their use of ultrasound for internal jugular vein cannulae placement. Only 27% use 2D ultrasound as their first choice technique, although 35% use it as their first choice when teaching. There was no significant difference in practice between those working within a sub specialty in anaesthesia. There continues to be discrepancies between the application of the guideline and how senior anaesthetists both site and teach the placement of internal jugular vein central venous cannulae.

PMID: 19032257 [PubMed - indexed for MEDLINE]

Metabolic acidosis in the critically ill: part 2. Causes and treatment.

Anaesthesia. 2008 Apr;63(4):396-411

Authors: Morris CG, Low J

The correct identification of the cause, and ideally the individual acid, responsible for metabolic acidosis in the critically ill ensures rational management. In Part 2 of this review, we examine the elevated (corrected) anion gap acidoses (lactic, ketones, uraemic and toxin ingestion) and contrast them with nonelevated conditions (bicarbonate wasting, renal tubular acidoses and iatrogenic hyperchloraemia) using readily available base excess and anion gap techniques. The potentially erroneous interpretation of elevated lactate signifying cell ischaemia is highlighted. We provide diagnostic and therapeutic guidance when faced with a high anion gap acidosis, for example pyroglutamate, in the common clinical scenario 'I can't identify the acid--but I know it's there'. The evidence that metabolic acidosis affects outcomes and thus warrants correction is considered and we provide management guidance including extracorporeal removal and fomepizole therapy.

PMID: 18336491 [PubMed - indexed for MEDLINE]

Metabolic acidosis in the critically ill: part 1. Classification and pathophysiology.

Anaesthesia. 2008 Mar;63(3):294-301

Authors: Morris CG, Low J

Metabolic acidaemia (pH < 7.35 not primarily related to hypoventilation) is common amongst the critically ill and it is essential that clinicians caring for such patients have an understanding of the common causes. The exclusive elimination routes of volatile (carbon dioxide), organic (lactic and ketone) and inorganic (phosphate and sulphate) acids mean compensation for a defect in any one is limited and requires separate provision during critical illness. We discuss the models available to diagnose metabolic acidosis including CO2/HCO3(-) and physical chemistry-derived (Stewart or Fencl-Stewart) approaches, but we propose that the base excess and anion gap, corrected for hypoalbuminaemia and iatrogenic hyperchloraemia, remain most appropriate for clinical usage. Finally we provide some tips for interpreting respiratory responses to metabolic acidosis and how to reach a working diagnosis, the consequences of which are considered in Part 2 of this review.

PMID: 18289237 [PubMed - indexed for MEDLINE]