Indian Pediatrics - Editorial

Brief Reports

Indian Pediatrics 2001; 38: 65-68

Error in Neonatal Daily Weight Measurement Caused by Equipment Weights

Rekha Solomon
Atanu Kumar Jana
Sridhar S.
Kurien Anil Kuruvilla

From the Department of Neonatology, Christian Medical College Hospital, Vellore-632 004, Tamil Nadu, India.

Correspondence to: Dr. A.K. Jana, Professor and Head, Neonatology Department, Christian Medical College Hospital, Vellore 632 004, Tamil Nadu, India.

Manuscript received:April 24, 2000;
Initial review completed: June 7, 2000;
Revision Accepted: June 30, 2000

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.

Methods

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.

Results

The weight of commonly used equipments is given in Table I.

TABLE I – Weights of Community Used Neonatal Equipments.
Sl.No.	Equipments	Company or Manufacturer	Size/No.	Mean weight (g)
1.	Infant feeding tube	Romsons	5 Fr	1.99 ± 0.01
			6 Fr	2.40 ± 0.36
			8 Fr	3.61 ± 0.40
2.	Intravenous catheter with wings	Vialon	24 G (0.75 cm)	0.59 ± 0.07
3.	Neonatal vascular armboard (splint)	CMCH, Vellore		8.73 ± 0.97
4.	Infant line with adaptor	George Philip		3.71 ± 0.25
5.	Intravenous bacterial filter	Laboratoire Plastimed		18.82 ± 0.59
6.	Endotracheal tube	Portex	2.5 mmID	3.05 ± 0.06
		Portex	3.0 mmID	3.29 ± 0.09
		Portex	3.5 mmID	3.35 ± 0.22
		Portex	4.0 mmID	4.25 ±0.37
7.	Epicutaneous central venous catheter (Silicon)	Vyggon	No.2184	4.17 ± 0.58
8.	Umbilical clamp (Klik-Clamp)	Romsons		2.04 ± 0.05
9.	Umbilical silastic catheter	Vygon	5 FR	1.61 ± 0.03
		Vygon	6 FR	1.83 ± 0.10
10.	3 way stopcock	George Philip		2.75 ± 0.05
11.	Pediatric urine collection bag	Minicom (Teckplast)		1.74 ± 0.12
12.	Micropore (Dermalite)	Johnson & Johnson	strip of 10 cm ´ 2.5 cm	0.20 ± 0.03
13.	Adhesive	- do-	strip of 10 cm ´ 2.5 cm	0.57 ± 0.02
Fr - French, ID - Internal Diameter, G-Gauge.

The findings of this observation was applied to several babies undergoing intensive care in the nursery. An example is given below.

Example

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:

Endotracheal tube No. 2.5 mmID

2 umbilical catheters 5 Fr and 6 Fr

IV filter with a 3 way stopcock

Peripheral venous line (intravenous cannula and infant line)

2 Splints (1 for peripheral venous cannula, second for filter)

The baby was weighed with these pieces of equipment attached.

Combined weight (Baby + Equipment) = 970 g

Equipment weight = 53.4 g

Baby’s actual weight = 916.6 g

In this example, equipment attached to the baby accounts for 5.5% of the observed weight.

Discussion

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.

Funding: None.
Competing interests: None stated.

Key Messages

Accurate measurement of daily weight is critical in the management of very low birth weight infants and likelihood of error increases with the number of pieces of equipment attached to the infant.
A reference table documenting the commonly used equipment in the nursery with their weights should be available.
Weigh the infant with equipment attached and subtract the equipment weight to obtain the actual infant weight.

References

Alsop-Shelds L, Alexander H. A study of errors that can occur when weighing infants. J Adv Nurs 1997; 25: 587-594.

Engstrom JL, Kavanaugh K, Meier PP, Boles E, Hernandez J, Wheeler D, Chuffo R. Reliability of in-bed weighing procedures for critically ill infants. Neonatal Netw 1995; 14: 27-33.