We examined the effect of core and skin temperature on the accuracy of two pulse oximeters (Nellcor Symphony and Hewlett Packard saturation module, M1020A) and a transcutaneous PCO 2 monitor (Fastrac Transcutaneous monitor) immediately after cardiac surgery in a group of newborns and infants. Seventy-nine sets of data were collected from 46 patients. Core temperatures ranged from 35.3°C to 39.4°C, skin temperatures ranged from 27.0°C to 37.4°C and core-skin temperature gradients ranged from 0.1°C to 10.1°C. Data analysis consisted of comparing the difference between transcutaneous PCO 2 and arterial PCO 2 and the differences between oxygen haemoglobin saturation measured by both pulse oximeters and oxygen haemoglobin saturation measured by co-oximeter to core temperature, skin temperature and core-skin temperature gradients. The mean differences±standard deviations and limits of agreement for transcutaneous PCO 2 and oxygen haemoglobin saturation measured by the Hewlett Packard and Nellcor pulse oximeters were 0.95±4.10 mmHg (-7.09 mmHg to 8.99 mmHg),-1.07±1.84% (-4.68% to 2.54%) and-1.23±2.23% (-5.60% to 3.14%) respectively. Analysis of correlation coefficients showed that the accuracy of the transcutaneous PCO 2 monitor and the pulse oximeters were not affected by core temperature, skin temperature or core-skin temperature gradient in the ranges encountered. We therefore conclude that these devices are acceptably accurate and suitable for use in infants when core and skin temperatures and core-skin temperature gradient are in the range normally found after cardiac surgery.

The humidity output of heated humidifiers may be compromised by inlet gas temperatures exceeding approximately 26°C, with humidity dropping below the recommended levels for intubated patients. A new version of the Fisher & Paykel MR850 humidifier claims to deal with this problem by offering a humidity compensation option. The present study tested this feature by measuring humidity output using the gravimetric method and a hygrometer at different inlet gas temperatures (16.6°C to 40.0°C) with compensation on and off. It was found that the compensation is effective in maintaining humidity levels despite high inlet gas temperatures.

Pupillary responses are a simple test commonly used as a predictor of outcome after severe brain injury. It is also common for clinicians to associate bilaterally absent pupillary responses with very poor prognosis. We report a series of cases of severely brain injured children with bilaterally absent pupillary responses who had favourable outcomes. From a group of 89 patients with brain injury, 32 had bilaterally absent pupillary responses and six (four with traumatic brain injury and two with infective brain injury) subsequently had favourable outcomes. This represents 18.8% of patients and should be a reminder to clinicians that the clinical sign of bilaterally absent pupillary responses is not always associated with a hopeless outcome.

We studied the interchangeability of two blood gas syringes (lohns, Hardie Health Care Products Pty Ltd and Marksman, Martell Medical Products Inc) for the collection of blood for the analysis of peo 2 , po 2 , pH, sodium, potassium and glucose in 71 intensive care unit patients. The interchangeability of these two syringes with a specially designed syringe (Radiometer, Radiometer A IS) for the collection of blood for the analysis of ionized calcium was also studied. Analysis of pH, sodium, potassium and glucose showed no clinically significant differences between samples collected with lohns and Marksman syringes. However, differences in pe02 and p0 2 in samples collected with these syringes may be clinically significant if the p0 2 is less than lOO mmHg. There were no clinically significant differences in ionized calcium levels in blood samples collected with lohns, Marksman and Radiometer syringes. We conclude that lohns and Marksman syringes are interchangeable for the collection of blood for the analysis of peo 2 , po 2 , pH, sodium, potassium and glucose and they are also interchangeable with Radiometer syringes for the collection of blood for ionized calcium analysis.

The absorbance of NO (5–90 ppm) and NO2 (0.5–4 ppm) by a number of absorbers and filters was assessed via bench testing. All absorbers (Sodasorb, Purafil CP, Purafil Select, Sofnolime, Sofnofil and 50/50 mix of Sofnolime/Sofnofil) except Sodasorb absorbed NO almost completely. Only Sofnolime absorbed NO2 completely while Sodasorb and the Sofnolime/Sofnofil 50/50 mix had absorbances between 47% and 90%. The absorbance of four filters (ILF100, ILF150, ILF200 and HgCONO) as well as Sofnolime and the Sofnolime/Sofnofil 50/50 mix was tested in the expiratory port of a Servo 900C ventilator. All absorbers and filters produced a change in ventilator pressures. The HgCONO filter, Sofnolime and the Sofnolime/Sofnofil 50/50 mix all absorbed NO. At 80 ppm NO, the HgCONO filter had 100% absorbance for four hours while Sofnolime's absorbance was significantly reduced after one hour. All filters and absorbers tested on the ventilator except the Sofnolime/Sofnofil 50/50 mix and the ILF150 filter absorbed NO2 completely for a period ranging from 90 minutes to four hours. We recommend the HgCONO filter and Sofnolime to absorb both NO and NO2. If absorption of NO2 only is required we recommend the HgCONO, ILF100 or ILF200 filters or the Sofnolime absorber.