Mj Marsh

Clinical validation of cardiac output measurements using femoral artery thermodilution with direct Fick in ventilated children and infants.

Objective: To validate clinically cardiac output (CO) measurements using femoral artery thermodilution in ventilated children and infants by comparison with CO estimated from the Fick equation via a metabolic monitor. Design: Prospective, comparison study. Setting: Paediatric intensive care unit of a university hospital. Patients: 24 ventilated infants and children, aged 0.3 to 175 months (median age 19 months). Interventions: Oxygen consumption measurements were made and averaged over a 5-min period, at the end of which arterial and mixed venous blood samples were taken and oxygen saturations measured by co-oximetry, with CO being calculated using the Fick equation. Over this 5-min period, five sets of femoral arterial thermodilution (FATD) measurements were made and averaged. One comparison of CO values was made per patient. Results: Mean Fick CO was 2.55 l/min (range 0.24 to 8.71 l/min) and mean FATD CO was 2.51 l/min (range 0.28–7.96 l/min). The mean bias was 0.03 l/min (95 % confidence interval –0.07 to 0.14 l/min), with limits of agreement of –0.45 to 0.52 l/min. When indexed to body surface area, the mean Fick cardiac index became 3.51 l/min per m2 (1.52–6.98 l/min per m2) and mean FATD 3.49 l/min per m2 (1.74–6.84 l/min per m2). The mean bias was 0.02 l/min per m2 (95 % confidence interval –0.11 to 0.15 l/min per m2) with limits of agreement of –0.57 to 0.61 l/min per m2. The mean FATD coefficient of variation was 5.8 % (SEM 0.5 %). Conclusions: FATD compares favourably with Fick derived CO estimates in infants and children and may represent an advance in haemodynamic monitoring of critically ill children.

A comparison of pulmonary and femoral artery thermodilution cardiac indices in paediatric intensive care patients

We have assessed the agreement between pulmonary artery and femoral artery (COLD) thermodilution measurements of the cardiac index (C1) in a group of paediatric intensive care patients. The COLD method gave consistently higher cardiac index values than the pulmonary artery catheter (PAC); however, the difference was small, with a mean value of 0.191/min−1 m−2 or 4.4% of the mean cardiac index. This difference is not clinically important and suggests that, under these circumstances. the COLD system provides an acceptable alternative to the pulmonary artery catheter for measurement of the cardiac index at the bedside.

Continuous haemodynamic monitoring in children: use of transoesophageal Doppler

A wide range of invasive and non‐invasive techniques for monitoring the haemodynamic condition of critically ill patients is now available. A general reluctance on the part of paediatric intensive care specialists to use pulmonary artery thermodilution catheters and the need for constant realignment of hand‐held Doppler probes has necessitated the search for a technique which is relatively non‐invasive and provides continuous information on the haemodynamic condition of critically ill paediatric patients. We sought to establish if transoesophageal Doppler fulfilled these criteria. Eleven children who had recently undergone cardiac surgery were studied. Median age was 39 months and weight 14.9 kg. Five simultaneous pairs of measurements of cardiac index (CI: thermodilution) and minute distance (MD: transoesophageal Doppler) were made, as a baseline, when each child was haemo‐dynamically stable. Following a fluid challenge, five repeat pairs of measurements were made. The mean percentage changes for CI and MD were 16.4% (range 5.3‐44%) and 16.6% (3.4‐47.7%), respectively. The average coefficients of variation for measurements of CI and MD were 3.5% and 2.9%, respectively. The mean difference in percentage change between CI and MD was ‐0.5% (95% confidence interval for the bias –4% to 3%; limits of agreement –10.7 to +9.7%). Our study indicates that transoesophageal Doppler is reproducible, easy to use and provides clinically acceptable information when following changes in CI in haemodynamically stable paediatric patients. ? Cardiac index, minute distance, pulmonary artery catheter, thermodilution, transoesophageal Doppler

Early detection of necrotizing enterocolitis by gastrointestinal tonometry

The diagnosis of necrotizing enterocolitis (NEC) in neonates has traditionally depended on a combination of clinical signs, biochemical parameters and radiological changes. The measurement of intramucosal pH by gastrointestinal tonometry provides a simple means of long‐term monitoring which may detect the development of NEC before conventional techniques. We present our experience of tonometry in two‘at risk’term neonates with Hypoplastic Left Heart Syndrome.

An emotional 13-year-old girl

Pronounced emotional lability is a feature of Sydenham’s chorea not often mentioned in standard texts, but highlighted in a review by Majeed. Features such as a preference to be alone, a short attention span, and signs of depression or euphoria should alert the clinician to the diagnosis. Our patient did not develop choreiform movements, but this feature is usually a late manifestation. The developed world is said to have a declining incidence of acute rheumatic fever, although there have been reports of a resurgence in the USA. Our report highlights the importance of considering the diagnosis in patients with symptoms that fulfil criteria set out by the American Heart Association, and which are learnt by rote by all of us, but put to use only very rarely in the UK.