The recommended dosage of phenytoin for a child is 7 mg/kg/24 h given q h. The child's weight is 55 lb. The medication is supplied in 125 mg/5 mL. How many milliliters will be administered for each dose? . .

Choice A rationale

A decrease in respiration rate from 40 to 32 breaths/min in an infant with RSV, while a reduction, does not necessarily indicate immediate deterioration requiring urgent reporting unless accompanied by other signs of respiratory distress. The normal respiratory rate for an infant typically ranges from 30 to 60 breaths/min. This change might reflect an improvement or a less acute phase.

Choice B rationale

A decrease in heart rate from 110 to 100 beats/min in an infant, while a slight reduction, still falls within the normal range for an infant's heart rate (typically 90-160 beats/min). This change alone is not usually indicative of immediate critical deterioration, especially without accompanying signs of hypoxemia or circulatory compromise.

Choice C rationale

A "quiet chest" following a previous assessment of wheezing in an infant with RSV is an ominous sign. Wheezing is caused by air moving through constricted airways. A sudden cessation of wheezing, despite persistent respiratory distress, suggests severe bronchoconstriction and impending respiratory failure, as airflow has become so minimal that it no longer produces audible sounds.

Choice D rationale

An oxygen saturation of 90% is below the acceptable normal range (typically 95-100%) and indicates hypoxemia, requiring attention and intervention. However, while concerning, it is not as immediately life-threatening as a "quiet chest" which signals impending respiratory arrest due to absent air movement.

Step 1: Convert pounds to kilograms. 72.6 lb ÷ (2.2 lb/1 kg) = 33 kg.

Step 2: Calculate the lower end of the daily dosage range in milligrams. 20 mg/kg/day × 33 kg = 660 mg/day.

Step 3: Calculate the upper end of the daily dosage range in milligrams. 40 mg/kg/day × 33 kg = 1320 mg/day.

Step 4: Calculate the lower end of the single-dose range in milligrams. 660 mg/day ÷ 3 doses/day = 220 mg/dose.

Step 5: Calculate the upper end of the single-dose range in milligrams. 1320 mg/day ÷ 3 doses/day = 440 mg/dose. The single-dose range for this child is 220 mg to 440 mg.