Steven Cunningham

Intra-arterial blood pressure reference ranges, death and morbidity in very low birthweight infants during the first seven days of life.

OBJECTIVES We aimed to: (1) assess the association of average, low, high and variable mean blood pressure (mbp) on death and the common morbidities of very low birthweight infants, and in doing so, (2) to derive representative reference ranges for mbp in very low birthweight infants. STUDY DESIGN This five year retrospective study assessed 1 min computer recordings of intra-arterial mbp in 232 very low birthweight infants over the first 7 days of life in a tertiary NICU. Four measures of mbp were assessed: average, variability, maximum (per time period), and percentage of time with a mean blood pressure less than the infants gestation. Correlation was made with death and the development of intraventricular haemorrhage (IVH), periventricular leukomalacia (PVL) and retinopathy of prematurity (ROP). RESULTS The mbp increased with increasing birthweight and postnatal age (though with a slight decrease on days 6 and 7). Birthweight, gestation and colloid support (adjusted for birthweight and gestation) were the only factors significantly associated with mbp. IVH was predominantly associated with a low and variable mbp on the day IVH was noted or the day before. PVL and ROP were not associated with blood pressure. CONCLUSIONS These reference ranges include more infants and data than previously published and relate mbp in this cohort to morbidity and mortality. They could assist clinicians in judging appropriate mbp for birthweight.

A randomized, controlled trial of computerized physiologic trend monitoring in an intensive care unit

OBJECTIVE To assess whether the provision of computerized physiologic trend data could improve outcome in newborn infants requiring intensive care. DESIGN Randomized, controlled trial, with subsidiary questionnaire studies. SETTING Tertiary neonatal intensive care unit with 12 intensive care cots. PATIENTS All infants admitted between January 1991 and September 1993 who were < or =32 wks gestation or >32 wks gestation, and ventilated for >4 hrs or asphyxiated. INTERVENTIONS Randomization to one of four groups for first 7 days of life: A) no display of trend data; B) continuous display of trend data; C1) alternating 24-hr display of trend data, starting with display in first 24 hrs; and C2) alternating 24-hr display of trend data, starting with no display in first 24 hrs. MEASUREMENTS AND MAIN RESULTS The short-term effects of monitoring on patient outcome was judged by volume of colloid given, number of blood gases taken, and by measurement taken from cranial Doppler ultrasound. Medium-term measures included time ventilated, time given supplemental oxygen, death, time to death or discharge, and cranial ultrasound at discharge. Long-term outcome was assessed by neurodevelopmental status at age 1 to 4 yrs of age. Staff and parent questionnaires assessed their respective attitudes to the introduction of this technology. None of the patient outcome measures, short-, medium-, or long-term, demonstrated any significant benefit from the provision of computerized physiologic trend monitoring. Staff questionnaires demonstrated an acceptance of the system and an improved understanding of neonatal physiology as a result of computerized physiologic trends. Parent questionnaires demonstrated increased anxiety caused by the system in 11% of parents, although only 1% of parents continued to have concerns if the system were able to help their child. CONCLUSIONS A randomized, controlled trial was unable to demonstrate any benefit to patients resulting from the introduction of a computerized physiologic trend monitoring system. Benefits of the system have been recognized, however, in subsidiary studies, staff education, and research studies.

The practical management of artifact in computerised physiological data

Computerised physiological data contains artifact that needs to be identified and possibly removed. Whilst computers may eventually satisfactorily perform this function, at present only manual removal is possible for the majority of intensive care computer groups. We assessed the effects of artifact and its removal on the physiological data of 3 patients. Artifact was manually removed from 7 days of data in 4 parameters (heart rate, respiratory rate, systolic blood pressure [sbp] and transcutaneous oxygen [tcpO2]) by 3 independent observers. Six hour time periods were analysed. Median and mean values before and after the manual removal of artifact were compared. Overall. 6.5% of data was removed as artifact. This was greatest for tcp02 (9.9%) and sbp (10.6%), with smaller amounts for respiratory rate (2.8%) and heart rate (2.4%). Sbp showed a marked difference in the amount of data removed between patients, whereas tcp02 data contained quite large volumes of artifact, but this was fairly consistent between patients, Removal of artifact affected mean values more than median values. One observer considered that both physiological and non-physiological artifact should be removed, whereas the other two observers removed only non-physiological artifact. Agreement in results between the latter was good. Our results suggest that interobserver variability should have a minimal effect on values, once rules identifying the type of artifact to be removed are agreed. Removal of artifact did not have a clinically significant effect on results, but may be an important consideration in the statistical analysis of computerised physiological data.

Comparison of nurse and computer charting of physiological variables in an intensive care unit

Objectives. To compare charting of physiological parameters manually by nurses and automatically by computer and so decide whether this task could accurately be performed by computer.Subject/setting. 101 consecutive patients admitted for tertiary neonatal intensive care.Design. Direct comparison of 48 hours of data collected by both methods. Computer data stored each second and the hourly median compared with the single hourly value noted by the nurse.Methods. All patients were monitored by standard patient monitor and a computer. Four physiological parameters were compared between nurse and computer (both derived information from the standard patient monitor): heart rate, transcutaneous oxygen, mean blood pressure, central temperature. A random 51% of patients had the computer data displayed as trends at the cotside. Comparison of the hourly nurse observation and a computer hourly median value. Computer data was compared before and after the removal of artifact. In addition, the effects on nursing observations of either display or non display of the computer trend data was assessed.Results. Nurse and computer observations were statistically significantly different (p<0.001), though these were not clinically important. Nurses tended to note a higher figure than the computer median. The cotside display of computer data improved consistency between the nurse and computer observations. Artifact present in the data had little influence on the accuracy of the computer median value.Conclusions. Computer systems can accurately chart physiological data, providing a more flexible record with a minimal risk to data reliability from artifact.

Neonatal blood pressure waves are associated with surges of systemic noradrenaline.

Neonatal blood pressure (BP) waves have been linked to neonatal illness. We investigated plasma levels of vasoactive hormones when BP waves were observed. Peak and trough noradrenaline levels correlated with mean BP (p = 0.028). There was no relationship to adrenaline, dopamine or endothelin levels.

Long Term Outcome of Infants in a Randomised Controlled Trial of Computerised Physiological Trend Monitoring (CPTM). 77

Long Term Outcome of Infants in a Randomised Controlled Trial of Computerised Physiological Trend Monitoring (CPTM). 77

Daily Resistance Index in the First Week of Life and Outcome at 1 to 4 Years 25

Background Although doppler resistance index (RI) has some predictive value in asphyxiated term newborns, little is known of the long term predictive value of this measure for outcome in preterm infants admitted to neonatal intensive care (NICU).