Geometric method for measuring body surface area: a height-weight formula validated in infants, children, and adults

Evaluation of a height/plasma creatinine formula in the measurement of glomerular filtration rate

The clinical usefulness of the quantity height (cm)/plasma creatinine (Ht/Pcr) as a predictor of glomerular filtration rate (GFR) was investigated in 163 children with varying levels of renal function. Plasma creatinine levels (mumol/l) were measured by an automated reaction rate method. The results indicate that in rather more than half the children studied, an estimate of GFR adequate for ordinary clinical purposes will be obtained from Ht/Pcr, or from the derived formula GFR (ml/min per 1.73 m2) = 40 Ht/Pcr. The accuracy of the prediction is greatest in children with reduced function (GFR less than 80 ml/min per 1.73 m2) and in this group of patients a change of GFR of 19 ml/min per 1.73 m2 or more is reliably detected by this method. We conclude that Ht/Pcr is a clinically useful aid to the estimation of renal function, reducing the need for formal GFR measurements by at least half.

Mechanocardiographic assessment of systolic time intervals in normal children

Systolic time intervals (STI) were measured in 469 normal children, aged 5.0 to 16.9 years, using simultaneous recordings of the electrocardiogram, phonocardiogram and an external carotid pulse tracing. The data were analyzed to define the influence of sex, age, cardiac cycle length, body weight (BW), body length (BL), and body surface area (BSA) on the left ventricular STI. Regression, equations were evaluated for the calculation of normal standards for the following STI: electromechanical systole (QS2), left ventricular ejection time (LVET), pre-ejection period (PEP) systolic quotient (PEP/LVET), isovolumic contraction time (IVCT), electroacustical delay (QS1), and additionally for the so-called tension time (TT), upstroke time (UT), and the ascending index (UT/LVET) of the carotid pulse wave. Heart rate was found to influence all of the STI but the ratio UT/LVET, which revealed to be independent of any variable. Besides heart rate, BSA proved to be a second relevant independent variable for QS2 and LVET, respectively BL for PEP, PEP/LVET and QS1. These findings are in accordance to the results of comparable echocardiographic studies but disagree previous mechanocardiographic studies in smaller groups of children in whom age and not the above-mentioned parameters of the individual development seemed to influence the STI. A second set of equations was evaluated for the calculation of 95%-prediction intervals for the particular STI permitting to define abnormalities of the STI in individual children.

Two-compartment gentamicin pharmacokinetics in premature neonates: a comparison to adults with decreased glomerular filtration rates

Eleven premature neonates received gentamicin sulfate for treatment of suspected gram-negative sepsis with accompanying respiratory distress syndrome. Serum gentamicin concentrations were measured during and after treatment to monitor therapy and to determine the two-compartment distribution and elimination characteristics of the drug. The measured pharmacolinetic parameters were compared to those of 14 adult patients with similar glomerular filtration rates. Neonates, like adults and children, had a prolonged persistence of gentamicin in the serum after treatment was stopped. Although there were marked differences between neonates and adults in administered dose, clearance, and distribution volume when the data were expressed on the basis of body weight, these differences were no longer apparent when the data were expressed relative to body surface area. Differences in gentamicin disposition cannot explain the apparent lack of aminoglycoside nephrotoxicity among premature neonates.

Indomethacin and renal function in premature infants with persistent patent ductus arteriosus

Renal function during indomethacin treatment was studied in 12 premature infants with patent ductus arteriosus. Decreases in urinary flow rate, GFR, and CH2O by 56, 27, and 66%, respectively, occurred during Indo therapy. Urinary excretion rates of ions were also reduced: Na by 70%, Cl by 79%, K by 40%. These changes were accompanied by slight decreases in plasma sodium concentration and osmolality. Except for GFR and urinary Na and osmolality, all these functions returned to pretreatment values one to two weeks after stopping the drug.

Gastric emptying in preterm infants

The gastric emptying of meals of human milk and infant formula was studied in 11 healthy preterm (AGA) infants at a postnatal age of 1-9 weeks corresponding to 33-38 weeks of gestational age. A total of 30 studies were performing using a marker dilution technique. Gastric emptying of meals of human milk followed a biphasic emptying pattern with an initial fast phase. In about 25 min half of the meal had left the stomach. The emptying of meals of adapted infant formula usually followed a linear pattern and half the meal had left the stomach after 51 min. After one hour an average of 24.8 ml of human milk and 19.2 ml of infant formula had left the stomach.