A Durward

Incidence of hyponatraemia and hyponatraemic seizures in severe respiratory syncytial virus bronchiolitis

Aim: To document the incidence and early evolution of hyponatraemia (serum sodium <136 mmol 1−1) associated with respiratory syncytial virus (RSV) bronchiolitis in infants requiring intensive care. Methods: In a retrospective review over two winter seasons, 130 infants were admitted with confirmed RSV infection, of whom 39 were excluded because of either pre‐existing risk factors for hyponatraemia: diuretic therapy (n= 14), cardiac disease (n= 10), renal disease (n= 2) or lack of admission sodium data (n= 13). Results: The incidence of admission hyponatraemia in the remaining infants (median age 6 wk) was 33% (30/91), with 11% (10/91) exhibiting a serum sodium less than 130 mmol 1−1. Hyponatraemic and normonatraemic infants were of a similar age (median 6 vs 7 wk, p= 0.82). With fluid restriction and diuretic therapy, the incidence of hyponatraemia at 48 h had decreased to 3.3%, odds ratio 0.07 (95% confidence interval 0.02–0.24, p < 0.001). Four infants (4%) suffered hyponatraemic seizures at admission (sodium 114–123 mmol 1−1); three had received hypotonic intravenous fluids at 100–150 ml kg−1 d−1 before referral to intensive care. All four were managed successfully with hypertonic (3%) saline, followed by fluid restriction, resulting in immediate termination of seizure activity and normalization of serum sodium values over 48 h.

Hypoalbuminaemia in critically ill children: incidence, prognosis, and influence on the anion gap

Aims: Hypoalbuminaemia has significance in adult critical illness as an independent predictor of mortality. In addition, the anion gap is predominantly due to the negative charge of albumin, thus hypoalbuminaemia may lead to its underestimation. We examine this phenomenon in critically ill children, documenting the incidence, early evolution, and prognosis of hypoalbuminaemia (<33 g/l), and quantify its influence on the anion gap. Methods: Prospective descriptive study of 134 critically ill children in the paediatric intensive care unit (ICU). Paired arterial blood samples were taken at ICU admission and 24 hours later, from which blood gases, electrolytes, and albumin were measured. The anion gap (including potassium) was calculated and then corrected for albumin using Figge’s formula. Results: The incidence of admission hypoalbuminaemia was 57%, increasing to 76% at 24 hours. Neither admission hypoalbuminaemia, nor extreme hypoalbuminaemia (<20 g/l) predicted mortality; however, there was an association with increased median ICU stay (4.9 v 3.6 days). After correction for albumin the incidence of a raised anion gap (>18 mEq/l) increased from 28% to 44% in all samples (n = 263); this discrepancy was more pronounced in the 103 samples with metabolic acidosis (38% v 73%). Correction produced an average increase in the anion gap of 2.7 mEq/l (mean bias), with limits of agreement of ±3.7 mEq/l. Conclusion: Admission hypoalbuminaemia is common in critical illness, but is not an independent predictor of mortality. However, failure to correct the anion gap for albumin may underestimate the true anion gap, producing error in the interpretation of acid-base abnormalities. This may have treatment implications.

Treatment of plastic bronchitis in acute chest syndrome of sickle cell disease with intratracheal rhDNase

Plastic bronchitis, a condition associated with widespread mucous plugging of the tracheobronchial tree, is an increasingly recognised bronchoscopic finding in acute chest syndrome of sickle cell disease. Removal of casts by bronchoscopy is technically challenging. We describe a child with acute chest syndrome where bronchoscopic removal of extensive tracheobronchial plastic casts was facilitated by intratracheal rhDNase.

A comparison of three scoring systems for mortality risk among retrieved intensive care patients

Aims: To assess the impact of two paediatric intensive care unit retrieval teams on the performance of three mortality risk scoring systems: pre-ICU PRISM, PIM, and PRISM II. Methods: A total of 928 critically ill children retrieved for intensive care from district general hospitals in the south east of England (crude mortality 7.8%) were studied. Results: Risk stratification was similar between the two retrieval teams for scores utilising data primarily prior to ICU admission (pre-ICU PRISM, PIM), despite differences in case mix. The fewer variables required for calculation of PIM resulted in complete data collection in 88% of patients, compared to pre-ICU PRISM (24%) and PRISM II (60%). Overall, all scoring systems discriminated well between survival and non-survival (area under receiver operating characteristic curve 0.83–0.87), with no differences between the two hospitals. There was a tendency towards better discrimination in all scores for children compared to infants and neonates, and a poor discrimination for respiratory disease using pre-ICU PRISM and PRISM II but not PIM. All showed suboptimal calibration, primarily as a consequence of mortality over prediction among the medium (10–30%) mortality risk bands. Conclusions: PIM appears to offer advantages over the other two scores in terms of being less affected by the retrieval process and easier to collect. Recalibration of all scoring systems is needed.

The outcome of patients with upper airway obstruction transported to a regional paediatric intensive care unit

Abstract The diagnoses, transfer, management and outcome of patients with upper airway obstruction (UAO) admitted from district general hospitals (DGH) to a regional paediatric intensive care unit were retrospectively reviewed over a 3.5-year period. Sixty-seven patient episodes were analysed. Fifty-two cases (78%) underwent tracheal intubation prior to transport with a low morbidity for both procedures. The most common diagnosis was viral croup (n= 34, 51%) with a median duration of intubation of 5 days, with subglottic stenosis being the next most common category (n= 10, 15%), median duration of intubation 7 days. Inhaled budesonide was used prior to intubation in 12 (35%) of those with croup, and inhaled bronchodilators in 28%, possibly reflecting diagnostic uncertainty. Patients with croup treated with budesonide were significantly less likely to require intubation (P= 0.04). The re-intubation rate for patients with viral croup was uncomfortably high at 16% (4/25) despite the routine use of prednisolone throughout the intubation period. Successful extubation of patients with viral croup could not be predicted by age (P= 0.31), length of intubation (P= 0.94), endotracheal tube size, (P= 0.60) abnormalities on the chest X-ray (P= 1.0), or presence of secondary bacterial infection (P= 0.23). Conclusion Although viral croup remains the most common diagnostic category presenting at the DGH level with severe UAO, a wide range of other diagnoses is seen. Despite clear evidence of benefit, steroid administration to children presenting at the DGH with viral croup has not become routine practice. Once intubated, no reliable predictors of successful extubation were found amongst this patient group.

Evaluation of the 5-French saline paediatric gastric tonometer.

Objective: To evaluate the paediatric 5-French (Fr) saline-filled gastric tonometer. Design: (a) In vitro comparison of saline bath reference pCO2 with tonometric pCO2 measured by normal saline-filled and phosphate-buffered saline-filled 5-Fr tonometers, and by a recirculating gas tonometer. ( b) In vivo comparison of gastric intramucosal pCO2i, measured by normal saline-filled 5-Fr tonometer (NST) and simultaneously by recirculating gas tonometer (RGT) in ten paediatric intensive care patients. (c) In vivo comparison of pCO2i measured simultaneously by 2 NST 5-Fr tonometers, before and after enteral feeding, in ten paediatric intensive care patients. Measurements and main results: (a) Twenty consecutive measurements of pCO2 were made at constant reference pCO2 of 19, 38, 56, and 75 mmHg (2.5, 5.0, 7.5, and 10.0 kPa), respectively. The NST tonometer underestimated reference pCO2 by mean bias (limits of agreement) of 58 % (20 %), and the phosphate-buffered saline-filled tonometer by 6 % (26 %). The RGT showed mean bias 5.7 % with narrow limits of agreement (1.5 %). (b) In 50 paired (NST vs. RGT) in vivo measurements over pCO2i range 23–73 mmHg (3.0–9.7 kPa), the NST underestimated RGT pCO2i by a mean bias of 10 mmHg (1.3 kPa), with limits of agreement + /–10 mmHg (1.5 kPa). This resulted in NST consistently overestimating pHi and underestimating pCO2 gap (both P < 0.001). (c) One hundred simultaneous paired NST measurements were assessed (50 without, and 50 with enteral feeding). The mean biases (limits of agreement) were identical in the fasted and fed states 0.4 ± 6 mmHg, with no difference between the fed and fasting states (P = 0.7). Conclusions: There are inherent problems in the methodology of saline tonometry, which adversely affect the accuracy and reliability of the 5-Fr paediatric gastric tonometer in comparison to recirculating gas tonometry.

Mortality in meningococcal disease: please report the figures accurately

We read with great interest the two recent articles on mortality in meningococcal disease.1,2 While we would agree with the message contained in both articles, namely that the mortality associated with this condition has decreased with time, we have serious concerns regarding the presentation of the data in the paper from the St Mary’s group. Booy and colleagues report a crude mortality of 2% for the year 1997,2 a figure that has generated considerable media interest. Several reasons are cited for this falling mortality: the provision of mobile intensive care, meticulous attention to stabilising the patient whilst in the district hospital, and the existence of a specialist “sepsis” intensive …

“The influence of hyperchloraemia on acid--base interpretation in diabetic ketoacidosis”: reply to Dr. Rosival

We thank Dr. Rosival for his comments. Unfortunately, the questions he poses are beyond the scope of our manuscript: the study design did not permit investigation into the optimal treatment of a metabolic acidosis, nor whether a hyperchloraemic acidosis differs from ketoacidosis in terms of prognosis. The aim of our manuscript was to document, via a novel method for partitioning the base deficit, the acidifying effect of hyperchloraemia during the treatment of diabetic ketoacidosis. We showed that the accuracy of the base deficit in quantifying ketosis was reduced in the presence of hyperchloraemia. It is our hope that this approach may provide the clinician with a bedside tool to recognise the changing aetiology of metabolic acidosis in this condition, and thus inform a more rational approach to treatment. Indeed, as a referral centre we have noted that two of the commonest misinterpretations of a persistent metabolic acidosis in diabetic ketoacidosis are that it due to “decreased tissue perfusion” (requiring more fluid and thus propagating the hyperchloraemic acidosis) or “worsening ketoacidosis” (prompting an increase in the rate of insulin infusion). Similarly, our study was not designed to analyse the therapeutic benefit of alkalinising therapy. This has been addressed thoroughly in a consensus statement by the Pediatric Endocrine Society and the European Society for Paediatric Endocrinology to the effect that “treatment with bicarbonate confers no clinical benefit” based on supportive evidence from well-conducted cohort studies [1]. References