The usefulness of 'corrected' body mass index vs. self-reported body mass index: comparing the population distributions, sensitivity, specificity, and predictive utility of three correction equations using Canadian population-based data.

SummaryWe used portable ultrasound scans to identify relevant anatomical structures in the necks of 30 patients before percutaneous tracheostomy. We identified the tracheal midline, thyroid isthmus and blood vessels and located a safe level for needle insertion. Anterior jugular veins were seen in 15 patients; eight were near the midline and were considered vulnerable. Three veins were more than 4 mm in diameter and these larger vessels were electively ligated. Four patients had arteries which were considered vulnerable to damage. All patients underwent successful percutaneous tracheostomy. Portable ultrasound provides a simple method of screening for vulnerable blood vessels in the neck and for locating the midline before percutaneous tracheostomy. This method is particularly suitable for patients with landmarks that are difficult to visualise or palpate. Based on the ultrasonic findings we can make an informed decision about referral for surgical tracheostomy.

Although RA accumulates in patients with moderate/severe renal impairment, pharmacokinetic modelling predicts that RA concentrations during a 9 microg kg(-1) h(-1) remifentanil infusion for up to 15 days would not exceed those reported in the present study, for which no associated prolongation of mu-opioid effects was observed.

The femoral artery and vein are commonly used for access to the circulation. Accidental puncture of one vessel whilst attempting to cannulate the other is a common complication. Identification of relevant surface anatomical landmarks and ultrasonography of both groins was performed on 50 consecutive adult patients admitted to the intensive care unit. In most patients there was overlap of the artery over the vein far closer to the inguinal ligament than conventional anatomical texts would indicate. The frequency and degree of overlap increased as the vessels descended distally towards the knee. Surface anatomical landmarks were not useful in predicting the underlying anatomy. The side‐by‐side relationship of artery and vein is commonest close to the inguinal ligament. Therefore, to avoid damage to the neighbouring vessel, percutaneous access should be undertaken just below the inguinal ligament.

In order to test the hypothesis that urine colour can be used as an index of hydration in critically ill patients, we selected 40 intensive care and high‐dependency patients and correlated urine colour (scored on an eight‐point scale) with various indices of hydration: urine:plasma sodium, osmolality and urea ratios, urine output and central venous pressure. In addition, we compared the colour‐chart score with scores made by intensive care nurses (without the benefit of a colour chart) in order to test subjective assessment of urine colour. There were weak but statistically significant correlations between urine colour and urine output (Spearman's r = − 0.555) and between urine colour and urine:plasma sodium ratio (Spearman's r = − 0.459). Subjective assessment of urine colour appeared to be reliable. Thus, although urine colour does vary with hydration in the critically ill, assessment of urine colour adds little to the overall assessment of hydration in this group of patients.