GENERAL MONITORING EQUIPMENT

Pediatric weighing scales: Precise weight record is an essential component of pediatric care for: (a) growth monitoring, and (b) calculation of drug dosages.

Commonly used Weighing scales, in order of preference may be broadly divided into: (a) electronic scales, (b) beam-balances, and (c) spring balances (Fig.

Fig. 32.33: Weighing balance.

Fig. 32.34: Infantometer.

Infantometer is a wooden device to measure the length of children lt;2 years; with three parts: (a) graduated wooden platform to place the infant in supine position,

(b) fixed sole board and (c) sliding head board to adjust according to the child/s length (Fig. 32.34). Baby should be placed over infantometer platform in a correct position-straight head, fully extended legs and feet at right angles to legs, before adjusting the headboard to record the length on graduated scale.

Thermometers: Two types of thermometers are commonly used to record body temperature: (a) mercury-based, and (b) digital thermometers. Mercury­based thermometers are being gradually phased out due to environmental concerns of mercury leak.

• Mercury-based thermometers have two parts: (i) metallic bulb filled with mercury, and (ii) long graduated glass tube. On contact with body, mercury in the bulb expands and rises into glass tube. Extent of rise on graduated scale denotes body temperature. This expanded mercury column must be jerked back into the bulb (at least 2° below normal) before re-use.

Mercury based thermometers include: (a) standard clinical thermometers, and (b) low-reading Rectal thermometers. Rectal thermometers are shorter tubes with round or pear-shaped bulb without constriction at the neck, which can detect hypothermia lt; 35°C, specially in newborns. However, rectal thermometers

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Fig. 32.35: Clinical and rectal thermometer.

Fig. 32.36: Finger pulse oximeter.

are rarely used at present due to risk of trauma and infection (Fig. 32.35).

• Digital thermometers are mercury-free and use many types of sensors, e.g. resistance temperature detectors, thermocouple and thermistor, to provide direct digital display of the temperature after pre-determined time.

In children, temperature may be recorded at various sites, preferably using a digital thermometer, e.g. axilla, groin, oral cavity and rectum. Rectal temperature is 1°F higher than oral temperature, which in turn is 1°F higher than surface (axillary/groin) temperature. Thermometer should be kept in situ for 3-5 minutes for surface temperature and 1-2 minutes for core (rectal/ oral) temperature.

After use, thermometers should be washed, wiped and stored in a glass jar partly filled with a disinfectant like 70% isopropyl alcohol with 1% iodine. The jar should have a piece of cotton wool at the bottom to prevent breakage. Individual patient-specific thermometers are preferred at present to avoid cross infections.

BP instrument and cuffs are available in different sizes ranging from 3.5 cm and 4.5 cm (for preterms and term newborns, respectively) to maximum size of 17.5 cm for use in adolescents. Correct cuff size is important to measure the BP as smaller cuff tends give higher readings and vice versa. An ideal cuff size should cover ~2#8725;3^rd of arm length (Ch 17.12).

Two types of portable BP instruments are in use at present: (a) conventional mercury-based sphygmo­manometers, and (b) digital BP monitors. However, mercury-based thermometers are being gradually phased out due to environmental concerns of mercury leak.

Digital BP monitors work on oscillometric method of BP measurement and correct BP measurement practices should be followed for their use (Ch 17.12).

Finger pulse oximeter is a simple non-invasive method to monitor percentage of hemoglobin saturated with oxygen (SaO₂).

It consists of a patient's probe attached to finger or earlobe and a central data processing unit with SaO₂ display. The clip-like probe has a light source on one lip and a photosensor on other lip, to monitor the intensity of light traversed through pulsating capillary bed (Fig. 32.36).

Accuracy of pulse oximeter is high (+ 2%) till SaO₂ is gt;70% but tends to be unreliable below these values. False values may also be obtained due to: (a) low capillary perfusion, e.g. shock, (b) presence of abnormal hemoglobin, e.g. methemoglobin or carboxyhemoglobin, (c) optic interference with external light source, e.g. phototherapy or warmers.

BIBLIOGRAPHY

1. Hutin Y et al. Best infection control practices for intradermal, subcutaneous and intramuscular needle injections. Bull WHO. 2003;81:491-500.

2. Recommendations of IAP workshop on safe injection practices: Recommendations and IAP plan of action. Indian Pediatr. 2005;42:155.