Indian Pediatrics 2001; 38: 65-68
Error in Neonatal Daily Weight Measurement Caused by Equipment Weights
Atanu Kumar Jana
Kurien Anil Kuruvilla
Monitoring of an infant’s daily weight is a sensitive index of neonatal well being. Accurate weighing is also important in fluid and electrolyte management and drug dosage calculations. This is particularly important in the care of very low birth weight babies. There are very few studies documenting the effect of equipment attached to the baby on the variability of the weight(1,2). This study was conducted in a Neonatal Intensive Care Unit to assess the magnitude of the problem and the remedial measures that could be undertaken to address this.
Pieces of neonatal equipment commonly used in nursery were weighed as used in day-to-day practice. The items were weighed on Libror Aeg 220 machine manufactured by Simadzu, Japan. The scale was calibrated to 10-4 g precision. Prior to this study, all the observers involved measured weight of 3 different objects three times each and the differences between the measurements taken by them did not reach any statistical significance.
A careful search was made in the nursery to identify the commonly used equipment in the care of sick neonates and thirteen such pieces were identified. The observers weighed each piece of equipment separately and each of them was blinded to the other’s weight measurements.
The weight of commonly used equipments is given in Table I.
The findings of this observation was applied to several babies undergoing intensive care in the nursery. An example is given below.
A 3-day-old neonate born at 28 weeks gestation with birth weight of 950 g was being ventilated for Hyaline Membrane Disease. The following pieces of equipment were attached to the baby:
The baby was weighed with these pieces of equipment attached.
In this example, equipment attached to the baby accounts for 5.5% of the observed weight.
Comprehensive medical management of sick newborns in intensive care units require attachment of several pieces of equipment on the baby. It has been found that the likelihood of errors in weighing increase with the number of pieces of equipment attached to the baby. It is a customary practice to weigh the baby with the pieces of equipment held above the body surface. However, variations in weight have been found according to height above the patient and position in which it is held(2).
For calculation of drug dosages and fluid therapy, knowing exact weight of the baby is important as miscalculation of drug dosages and fluid requirements would have a deleterious effect on the baby. Every piece of equipment is manufactured by different firms with different sizes and shapes; thus the weight of these pieces also vary considerably. An effective campaign should be made to impress upon and convince the manufacturers to mention the weight of that particular piece in the package, similar to the strength of a drug being mentioned on an ampoule or vial. From this study it is quite obvious that major mistakes in the management can be avoided if adjustment in the patients’ actual weight is done continuously whenever a new piece of equipment is attached or taken away from the baby’s body.
Every nursery should have a reference table listing weights of commonly used clinical items (including brand name and size) which is easily accessible to junior doctors and nursing personnel. This reference table could be updated periodically in case of any change in equipment used in nursery.
The baby should be weighed with equipment attached without lifting these above the plane of the body. Baby’s actual weight is calculated by subtracting weight of the equipment from the total weight of baby.
Contributors: AKJ conceived and initiated the study. RS, KAK and SS were responsible for collecting the data. AKJ and RS wrote the paper with contributions form SS. AKJ will act as the guarantor for the paper.