Evaluation of various laboratory assays in detection of heparin-induced thrombocytopenia in an adult general ICU.

INTRODUCTION: Heparin-induced thrombocytopenia (HIT) is an immune-mediated complication of heparin therapy. Our objective was (i) to compare various laboratory assays for HIT against clinical probability (4-T score) and (14) C-serotonin release assay (SRA), which was the composite gold standard and (ii) to determine the incidence of HIT in the ICU. METHODS: The study group (n = 217) consisted of consecutive ICU patients with heparin exposure followed by thrombocytopenia. The clinical probability (4-T score) was applied to the study group. Enzyme-linked immunosorbent assay (ELISA), particle gel immunoassay (PGIA), SRA, and platelet aggregation assay (PAA) were performed. RESULTS: The 4-T score showed that 1/217 patients had high probability, 48 had intermediate probability, and 168 had low probability for HIT. One patient was positive by SRA, three by PGIA, and 33 by ELISA. The incidence based on a combination of clinical features and laboratory findings was 1.8%. CONCLUSIONS: A greater number of false positives were observed by ELISA than by PGIA when compared to a composite gold standard of SRA and clinical probability. The incidence of SRA-positive HIT was 0.46% (1/217).

Treatment of acute infectious purpura fulminans with activated protein C.

Infectious purpura fulminans is associated with high mortality and morbidity despite standard antimicrobial therapy. We report satisfactory clinical outcome in two children with sepsis associated purpura fulminans who were treated with activated protein C (APC). There is need for proper evaluation of the efficacy of this extremely expensive therapeutic modality by randomized controlled trials before it is made standard of care in childhood infectious purpura fulminans.

Changing patterns of airway accidents in intubated ICU patients.

OBJECTIVE: To document the changes in patterns of airway accidents in intubated patients. DESIGN: Prospective recording of all airway accidents over two periods: 1994-1997 and 1998-1999. PATIENTS: Ventilated patients (5,046) intubated for 9,289 days over 4 years (1994-1997) and 2,932 ventilated patients intubated for 6,339 days over 2 years (1998-1999). MEASUREMENTS: The incidence and pattern of airway accidents over a 2-year period were compared to an earlier similar analysis done in the previous 4 years. RESULTS: The total accident rate in the 1994-1997 period was 36 in 5,046 patients over 9,289 intubated-patient days. The total accident rate in the period 1998-1999 was 20 in 2,932 patients over 6,339 intubated-patient days. The frequency of blocked tracheal tube increased to equal that of unplanned extubation (UE) of endotracheal tube (ETT) as the commonest airway accident. There were nine episodes of blocked tracheal tube in the two current years compared to four in the previous 4 years and there were nine episodes of UE in the two current years compared to 15 in the previous 4 years. There were a total of 18 ETT accidents in 2,930 patients over 5,309 ETT days compared to a total of two tracheostomy accidents in 67 patients over 1,030 tracheostomy days. CONCLUSIONS: We noted a change of the pattern of airway accidents. We noted an increasing trend in the incidence of blocked tracheal tubes, associated with an increased duration of heat and moisture exchanger-filters use. We also noted that the incidence of tracheostomy tube accidents was similar to that of ETT accidents in the current study, unlike the earlier study where tracheostomy tube accidents were more frequent than ETT accidents. This was due to the elimination of tracheostomy tube displacements during the later study period. We associated this with the use of adjustable tracheostomy length tubes.

Airway accidents in intubated intensive care unit patients: an epidemiological study.

OBJECTIVE: To assess the rate of occurrence and nature of airway accidents in intubated patients. DESIGN: Prospective recording of all airway accidents in a 16-bed multidisciplinary intensive care unit. PATIENTS: A total of 5,046 ventilated patients intubated for 9,289 days during 4 yrs. MEASUREMENTS AND MAIN RESULTS: We determined the number and diagnoses of intubated and ventilated patients, the number and timing of airway accidents, the type of tracheal tube used and duration for which the tube was in situ, the description of the type of accident, the severity of the accident, and its impact on the course of the patient's illness, whether the patient needed reintubation, and whether the accident was preventable. The total accident rate was 36 of 5,046 patients during 9,289 intubated patient days; 26 occurred in 5,043 endotracheally intubated patients during 8,446 patient endotracheal tube days. There were 10 tracheostomy-related accidents from a total of 79 patients with tracheostomies during 843 tracheostomy patient days. Six had severe consequences and one resulted in death. Eleven were completely preventable, 17 partly preventable, and 8 were considered unpreventable. Self-extubation was the most common accident. Seven of 13 self extubations occurred in patients due for elective extubation in the next few hours. Twelve of 15 patients with self- or accidental extubation of an endotracheal tube accidents did not require reintubation. CONCLUSIONS: Airway accidents occurred at low levels with even lower rates of resultant morbidity and mortality. Tracheostomy accidents are more common than those with an endotracheal tube.

Simultaneous lumbar and intraventricular manometry to evaluate the role and safety of lumbar puncture in raised intracranial pressure following subarachnoid haemorrhage.

We report a prospective investigation of a bedside test to evaluate the role and safety of lumbar puncture in raised intracranial pressure in patients with subarachnoid haemorrhage. Fourteen patients who underwent aneurysm clipping following subarachnoid haemorrhage were studied. All patients had intraventricular drains and needed high volume cerebrospinal fluid (CSF) drainage to maintain the normal intracranial pressure. A lumbar puncture was performed in these patients and the simultaneous opening lumbar and ventricular pressures noted, CSF was then drained via the lumbar puncture, and the simultaneous closing lumbar and ventricular pressures noted. In all patients, the opening lumbar pressure was close to the ventricular pressure. In 13 of 14 patients, CSF drainage resulted in an equivalent and simultaneous fall of ventricular pressure. We concluded that simultaneous measurement of lumbar and ventricular CSF pressure before and after lumbar CSF drainage allows identification of candidates with differential cranial and lumbar pressures and therefore indicates safety or risk of lumbar CSF drainage.