Survey of captive parrot populations around Port Phillip Bay, Victoria, Australia, for psittacine beak and feather disease virus, avian polyomavirus and psittacine adenovirus.

OBJECTIVE: This study investigated the prevalence of psittacine beak and feather disease virus (BFDV), avian polyomavirus (APV) and psittacine adenovirus (PsAdV) in captive psittacine birds around Port Phillip Bay, Victoria, Australia. METHODS: Samples of fresh droppings were collected from 118 psittacine birds (109 clinically normal and 9 with feather abnormalities) from 11 avaries in different locations and were used for detection of BFDV, APV and PsAdV using PCR. RESULTS: BFDV, APV and PsAdV were detected in 31%, 13% and 4%, respectively, of the specimens tested. One budgerigar was found to be co-infected with BFDV and PsAdV. At least one sample tested positive for BFDV at each location. CONCLUSION: This is the first report of the prevalence of BFDV, APV and PsAdV in Victoria and provides a foundation for future studies examining the influence of these viruses on the health of aviary birds in Victoria.

Assessment of the potential relationship between egg quality and infectious bronchitis virus infection in Australian layer flocks.

OBJECTIVE: This investigation aimed to determine if there was a relationship between the production of eggs with poor internal quality, as measured by poor Haugh units, by Australian layer flocks and the detection of infectious bronchitis virus (IBV) in the hens. Other risk factors including flock size, flock type, flock age, chicken breed and vaccination frequency were also assessed. METHODS: The study group comprised 17 flocks from 14 farms. Data relating to the factors investigated were requested on a regular basis. The Haugh unit data were used to grade eggs as good or poor based on the age and flock at the time of data collection. Cloacal swabs were collected from 20 chickens in each flock approximately every 6 weeks. RESULTS: IBV was detected from a majority of the flocks and in 68% of cases the IBV strain detected was an A-vaccine-related field strain. Three variant strains were detected. Detection of IBV in a flock, the farm type and flock size were identified as potential risk factors for the production of eggs with poor Haugh units. CONCLUSION: IBV is prevalent in Australian layer flocks, but infection was primarily subclinical. The results complement previous reports indicating that there are many potential risk factors for the production of eggs with poor Haugh units.

Application of high-resolution melting curve analysis for typing of fowl adenoviruses in field cases of inclusion body hepatitis.

OBJECTIVE: Fowl adenoviruses (FAdVs) cause inclusion body hepatitis (IBH) in chickens. In this study, clinical cases of IBH from Australian broiler flocks were screened for the presence and genotype of FAdVs. METHODS: Twenty-six IBH cases from commercial poultry farms were screened. Polymerase chain reaction (PCR) coupled with high-resolution melt (HRM) curve analysis (PCR/HRM genotyping) was used to determine the presence and genotype of FAdVs. For comparison, field isolates were also assessed by virus microneutralisation and nucleotide sequence analysis of the hexon loop 1 (Hex L1) gene. PCR detection of chicken anaemia virus (CAV) and infectious bursal disease virus (IBDV) was also employed. RESULTS: FAdV-8b and FAdV-11 were identified in 13 cases each. In one case, FAdV-1 was also identified. Cross-neutralisation was observed between the FAdV-11 field strain and the reference FAdV-2 and 11 antisera, a result also seen with the type 2 and 11 reference FAdVs. Field strains 1 and 8b were neutralised only by their respective type antisera. The FAdV-8b field strain was identical to the Australian FAdV vaccine strain (type 8b) in the Hex L1 region. The Hex L1 sequence of the FAdV-11 field strain had the highest identity to FAdV-11 (93.2%) and FAdV-2 (92.7%) reference strains. In the five cases tested for CAV and IBDV, neither virus was detected. The evidence suggested the presence of sufficient antibodies against CAV and IBD in the parent flocks and there was no indication of immunosuppression caused by these viruses. CONCLUSION: These results indicate that PCR/HRM genotyping is a reliable diagnostic method for FAdV identification and is more rapid than virus neutralisation and direct sequence analysis. Furthermore, they suggest that IBH in Australian broiler flocks is a primary disease resulting from two alternative FAdV strains from different species.

Periextubation caffeine in preterm neonates: a randomized dose response trial.

OBJECTIVE: To compare the effectiveness of three dosing regimens of caffeine for preterm infants in the periextubation period. METHODS: A randomized double-blind clinical trial of three dosing regimens of caffeine citrate (3, 15 and 30 mg/kg) for periextubation management of ventilated preterm infants was undertaken. Infants born <32 weeks gestation who were ventilated for>48 h were eligible for the study. Caffeine citrate was given as a once daily dose for a period of 6 days commencing 24 h prior to a planned extubation, or within 6 h of an unplanned extubation. The primary outcome measure was extubation failure, defined as neonates who were unable to be extubated within 48 h of caffeine loading or who required reventilation or doxapram dose within 7 days of caffeine loading. Continuous recordings of oxygen saturation and heart rate were undertaken in a subgroup of enrolled infants. RESULTS: A total of 127 babies were enrolled into the study (42, 40, 45, in the 3, 15, and 30 mg/kg groups, respectively). No statistically significant difference was demonstrated in the incidence of extubation failure between dosing groups (19, 10, and 11 infants in the 3, 15, and 30 mg/kg groups, respectively), however, infants in the two higher dose groups had statistically significantly less documented apnoea than the lowest dose group. Of the 37 neonates with continuous pulse oximetry recordings, those on higher doses of caffeine recorded a statistically significantly higher mean heart rate, oxygen saturations and less time with oxygen saturations <85%. CONCLUSIONS: This trial indicated there were short-term benefits of decreased apnoea in the immediate periextubation period for ventilated infants born <32 weeks gestation receiving higher doses of caffeine. Further studies with larger numbers of infants assessing longer-term outcomes are necessary to determine the optimal dosing regimen of caffeine in preterm infants.

Doxapram treatment for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Doxapram has been used to stimulate breathing and so prevent apnea and its consequences. OBJECTIVES: In preterm infants with recurrent apnea, does treatment with doxapram lead to a clinically important reduction in apnea and use of intermittent positive airways pressure (IPPV), without clinically important side effects? SEARCH STRATEGY: Searches were made of the Oxford Database of Perinatal trials, the Cochrane Collaboration Clinical Trials Register, MEDLINE 1966 - July 2001, Embase 1980 - July 2001, CINAHL 1982 - July 2001 (using text words 'doxapram', 'apnea or apnoea' and MeSH term 'infant, premature'), previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants, mainly in the English language. Abstracts of the Society for Pediatric Research were searched from 1996 - 2001 inclusive. Also an expert informant's search in the Japanese language was made by Prof. Y. Ogawa in 1996. SELECTION CRITERIA: All trials utilising random or quasi-random patient allocation, in which doxapram was used for the treatment of apnea in preterm infants were included. DATA COLLECTION AND ANALYSIS: Each author evaluated the papers for quality and inclusion criteria. Independent data extraction was carried out. MAIN RESULTS: Only one trial, which randomized 11 infants to intravenous doxapram and 10 infants to placebo, was found. There were fewer treatment failures after 48 hours in the group of preterm infants treated with doxapram (4/11) compared with the group treated with placebo (8/10). The wide confidence intervals made this result non-significant [RR 0.45 (0.20, 1.05)]. Only one infant, who was from the placebo group, was given IPPV. Of the seven responders by 48 hours in the group of 11 who received doxapram, five failed to respond between 48 hours and seven days after commencement of therapy. This gives a late failure rate of 9/11, similar to the short term failure rate in the placebo group of 8/10. It is not possible to evaluate the late responses of all those in the placebo group since they crossed over to a treatment arm. REVIEWER'S CONCLUSIONS: Although intravenous doxapram might reduce apnea within the first 48 hours of treatment, there are insufficient data to evaluate the precision of this result or to assess potential adverse effects. No longterm outcomes have been measured. Further studies are needed to determine the role of this treatment in clinical practice.

Doxapram treatment for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Doxapram has been used to stimulate breathing and so prevent apnea and its consequences. OBJECTIVES: In preterm infants with recurrent apnea, does treatment with doxapram lead to a clinically important reduction in apnea and use of Intermittent positive airways pressure (IPPV), without clinically important side effects? SEARCH STRATEGY: Searches were made of the Oxford Database of Perinatal trials, the Cochrane Collaboration Clinical Trials Register, MEDLINE (using text words 'doxapram', 'apnea or apnoea' and Mesh term 'infant, premature') previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants, mainly in the English language. Also an expert informant's search in the Japanese language was made by Prof. Y. Ogawa in 1996. SELECTION CRITERIA: All trials utilising random or quasi-random patient allocation, in which doxapram was used for the treatment of apnea in preterm infants were included. DATA COLLECTION AND ANALYSIS: Each author evaluated the papers for quality and inclusion criteria. Independent data extraction was carried out. MAIN RESULTS: Only one trial, which randomized 11 infants to intravenous doxapram and 10 infants to placebo, was found. There were fewer treatment failures after 48 hours in the group of preterm infants treated with doxapram (4/11) compared with the group treated with placebo (8/10). The wide confidence intervals made this result non-significant [RR 0.45 (0.20, 1.05)]. Only one infant, who was from the placebo group, was given IPPV. Of the seven responders by 48 hours in the group of 11 who received doxapram, five failed to respond between 48 hours and seven days after commencement of therapy. This gives a late failure rate of 9/11, similar to the short term failure rate in the placebo group of 8/10. It is not possible to evaluate the late responses of all those in the placebo group since they crossed over to a treatment arm. REVIEWER'S CONCLUSIONS: Although intravenous doxapram might reduce apnea within the first 48 hours of treatment, there are insufficient data to evaluate the precision of this result or to assess potential adverse effects. No longterm outcomes have been measured. Further studies are needed to determine the role of this treatment in clinical practice.

Caffeine versus theophylline for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Two forms of methylxanthine (caffeine and theophylline) have been used to stimulate breathing and so prevent apnea and its consequences. OBJECTIVES: In preterm infants with recurrent apnea, does caffeine treatment compared to theophylline treatment lead to a clinically important reduction in apnea and use of mechanical ventilation without clinically important side effects? SEARCH STRATEGY: Standard strategies of the Neonatal Review Group were used. Searches were made of the Oxford Database of Perinatal Trials, MEDLINE (see main text for strategy), previous reviews including cross references, abstracts conferences and symposium proceedings, expert informants, journal handsearching mainly in the English language. Also an expert informant's search in the Japanese language was made by Prof Y. Ogawa. SELECTION CRITERIA: All trials utilising random or quasi-random patient allocation in which caffeine was compared with theophylline for the treatment of apnea were eligible. Trial quality and eligibility were assessed independently by each author. There must have been an effort to exclude specific causes of apnea. Measures of the severity of apnea as well as the response to treatment must have been consistent with an evaluation of 'clinical apnea' as defined by the American Academy of Pediatrics (Nelson 1978). DATA COLLECTION AND ANALYSIS: Standard method of Neonatal Review Group was used. Each author assessed eligibility, trial quality and extracted data separately, then compared and resolved differences. Results are expressed as relative risk (RR) and risk difference (RD). From 1/RD the number needed to treat (NNT) was calculated. MAIN RESULTS: There is no difference in the failure rate (< 50% reduction in apnea/bradycardia) of treatment with caffeine or theophylline at 1-3 (two studies) or 5-7 days (one study). There is a higher mean rate of apnea in the standard caffeine group at 1-3 days [three studies, mean diff. 0.398 (0.334,0.463) /100min] but not at 5-7 days (two studies). Side effects, as indicated by tachycardia or feed intolerance leading to change in dosing, are lower in the caffeine group [typical RR 0.17 (0.04,0.72), RD -0.285 (-0.467,-0.104), NNT 3.5 (2.1, 9.6)]. This was consistent across the three studies. No trial reported the use of IPPV and no data are available to assess effects on growth and development. REVIEWER'S CONCLUSIONS: Caffeine appears to have similar short term effects on apnea/bradycardia to theophylline. In view of the other therapeutic advantages of caffeine (a higher therapeutic ratio, more reliable enteral absorption and a longer half life) this is the preferred treatment for apnea in preterm infants. The possibility that higher doses of caffeine might be more effective in extremely preterm infants needs further evaluation in randomized clinical trials.

Prophylactic methylxanthine for preventing of apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. In infants with apnea, methylxanthines have been successful as treatment to prevent further episodes. It is possible that prophylactic therapy, given to all very preterm infants from soon after birth, might prevent apnea and its associated hypoxemia and bradycardia. OBJECTIVES: In preterm infants, does prophylactic treatment with methylxanthine lead to less apnea, bradycardia, episodes of hypoxemia and use of mechanical ventilation, without clinically important side effects? SEARCH STRATEGY: The standard strategy of the Cochrane Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants and journal handsearching mainly in the English language. A search of MEDLINE was made in October 1998 covering the years 1966 -1998. SELECTION CRITERIA: All trials utilising random or quasi-random patient allocation, in which prophylactic methylxanthine (caffeine or theophylline) was compared with placebo or no treatment were eligible. Outcomes sought included the rate of apnea, bradycardia, hypoxemic episodes, use of IPPV, side effects such as tachycardia or feed intolerance, as well as longer term abnormal growth and development. DATA COLLECTION AND ANALYSIS: The standard methods of the Cochrane Collaboration and its Neonatal Review Group were used. The methodological quality of each trial was reviewed independently by each author. Each reviewer extracted data separately, then results were compared and differences resolved. The standard method of the Cochrane Neonatal Review Group was used to analyze the data, utilizing relative risk (RR) and risk difference (RD). MAIN RESULTS: Two studies examining a total of 104 infants were found. Both studied the effects of prophylactic caffeine. There were no meaningful differences between the caffeine and placebo groups in the number of infants with apnea, bradycardia, hypoxemic episodes, use of IPPV or side effects in either of the studies. Only two outcomes (use of IPPV and tachycardia) were common to the two studies and meta-analysis showed no substantive differences between the groups. REVIEWER'S CONCLUSIONS: The results of this review do not support the use of prophylactic caffeine for preterm infants at risk of apnea, bradycardia or hypoxemic episodes. Any future studies need to examine the effects of prophylactic methylxanthines in preterm infants at higher risk of apnea, bradycardia or hypoxemic episodes. This should include examination of important clinical outcomes such as need for IPPV, length of hospital stay and long term development.

Population pharmacokinetic modeling in very premature infants receiving midazolam during mechanical ventilation: midazolam neonatal pharmacokinetics.

BACKGROUND: Midazolam is used widely as a sedative to facilitate mechanical ventilation. This prospective study investigated the population pharmacokinetics of midazolam in very premature infants. METHODS: Midazolam (100 microg/kg) was administered as a rapid intravenous bolus dose every 4-6 h to 60 very premature neonates with a mean (range) gestational age of 27 weeks (24-31 weeks), a birth weight of 965 g (523-1,470 g), and an age of 4.5 days (2-15 days). A median (range) of four (one to four) blood samples, 0.2 ml each, were drawn at random times after the first dose or during continuous treatment, and concentrations of midazolam in serum were assayed by high-performance liquid chromatography. A population analysis was conducted using a two-compartment pharmacokinetic model using the NONMEM program. RESULTS: Average parameter values (interpatient percent coefficient of variation) for infants with birth weights 1,000 g or less were total systemic clearance (Cl(T)) = 0.783 ml/min (83%), intercompartmental clearance (Cl(Q)) = 6.53 ml/min (116%), volume of distribution of the central compartment (V1) = 473 ml (70%), and volume of distribution of the peripheral compartment (V2) = 513 ml (146%). For infants with birth weights more than 1,000 g they were as follows: Cl(T) = 1.24 ml/min (78%), Cl(Q) = 9.82 ml/min (98%), V1 = 823 ml (43%), and V2 = 1,040 ml (193%). The intrapatient variability (percent coefficient of variation) in the data was 4.5% at the mean concentration midazolam in serum of 121 ng/mL. CONCLUSIONS: Serum concentration-time data were used in modeling the population pharmacokinetics of midazolam in very premature, ventilated neonates. Clearance of midazolam was markedly decreased compared with previous data from term infants and older patients. Infants weighing less than 1,000 g at birth had significantly lower clearance than those weighing more than 1,000 g.

Population pharmacokinetics of intravenous amoxicillin in very low birth weight infants.

The population pharmacokinetics of amoxicillin were determined in 40 very premature infants (< or = 32 week gestational age, < 1500 g birth weight) who were receiving intravenous amoxicillin (50 mg/ kg, every 12 h) during the first days after birth. Serum amoxicillin concentrations were measured by HPLC. Clearance (CL) and volume of distribution (Vd) were modeled alone and under the influence of demographic and clinical covariates with a 1-compartment model with first-order elimination. The final population models with influential covariates were: CL(L/h) = 0.0000610 x body weight (g) and CL (L/h) = 0.0000805 x body weight (g), for infants also receiving gentamicin and not receiving gentamicin, respectively; Vd(L) = 0.678. The interpatient standard deviation (SD) for CL was 0.0351 L/h, and for Vd was 0.365 L. The intrapatient variability (SD) among observed and model-predicted serum concentrations was 13.7 mg/L. Evaluation of the predictive performance of this model in another group of infants (n = 16) indicated statistically insignificant bias (p > 0.05) of 3 mg/L among pairs of observed and Bayesian-predicted amoxicillin concentrations. The average population CL was smaller, but the average Vd and terminal half-life (t1/2) were larger than previously reported for healthy adults.

Haemodynamic responses and population pharmacokinetics of midazolam following administration to ventilated, preterm neonates.

OBJECTIVE: To evaluate the effects of intravenous midazolam on haemodynamic variables and cerebral blood flow velocity (CBFV) and to determine the pharmacokinetics using a population approach in very low birthweight (VLBW) ventilated infants. METHODOLOGY: Physiological variables were measured at predetermined times in 10 infants with birthweight < or = 1500 g following a bolus dose of intravenous midazolam (0.1 mg/kg). Heart rate, mean arterial blood pressure (MAP) and transcutaneous CO2 (TcPCO2) were recorded and CBFV was assessed by Doppler ultrasound. Midazolam concentrations were also measured and pharmacokinetic parameters determined using a population modelling package. RESULTS: No change in heart rate occurred during the study period, while the MAP decreased by 3 mmHg 5 min after midazolam administration compared to baseline values. A non-significant fall in TcPCO2 was seen at 20 min. Mean CBFV decreased from the baseline by 12% at 5 min, then returning to predose values. Midazolam concentrations were in the range shown to be effective in sedation of paediatric intensive care infants with the elimination being delayed in comparison to older children. CONCLUSIONS: As only minor cerebral and haemodynamic effects were found with the use of midazolam in stable ventilated preterm infants, it appears to be a safe, short-term sedative agent.

Perinatal outcome following conservative management of mid-trimester pre-labour rupture of the membranes.

OBJECTIVE: To assess perinatal outcome and the effect of antenatal steroid use following conservative management of 86 consecutive singleton pregnancies complicated by pre-labour rupture of membranes (ROM) in the mid-trimester (13-26 weeks; mean 22.8 weeks). METHODOLOGY: Review of obstetric and neonatal case notes between 1 January 1990 and 31 December 1993. RESULTS: The duration of ruptured membranes (latent period) ranged from 1.25 to 105 days (mean 23.8 days; median 14 days) and was inversely related to gestational age at ROM. There was clinical evidence of chorioamnionitis in 39.5% with placental histological changes consistent with chorioamnionitis in 76.6%. All infants were delivered before 33 weeks gestation (mean 26 weeks). Overall, the mortality rate was 43.0% but 62.5% in infants with ROM before 24 completed weeks gestation. Adverse outcome (defined as death, severe intraventricular haemorrhage (IVH) or periventricular leucomalacia (PVL)) occurred in 46.5% and was significantly related to both gestation at delivery and gestation at ROM. In the group (n = 40) with ROM before 24 weeks gestation, adverse outcome occurred in 65% and was inversely related to gestation at ROM independent of gestation at delivery. Antenatal steroid administration resulted in less adverse outcome independent of gestation at delivery (OR 0.31; 95% CI (0.09-0.98; P = 0.046)). CONCLUSION: From the neonatal perspective conservative management is justified for pregnancies with ROM at or after 24 weeks gestation; in this group the use of antenatal steroids prior to delivery may improve perinatal outcome. A poor outcome is associated with ROM that occurs before 24 weeks gestation.

Which milk for the preterm infant?

The optimal diet for the low birthweight infant is one that supports a growth rate approximating that of the third trimester of intra-uterine life without imposing stress on the developing metabolic or excretory systems. Although preterm human milk does not meet the energy and nutrient needs of developing preterm infants, the benefits such as contributions to host defence and gastrointestinal trophic aspects, and the psychological benefits of maternal-infant bonding, make it the preferred diet.

Saliva as a valid alternative to serum in monitoring intravenous caffeine treatment for apnea of prematurity.

Caffeine is a potentially useful alternative to theophylline for the treatment and prevention of apnea of prematurity because of its lower toxicity and longer terminal half-life. Monitoring of salivary caffeine concentrations is less invasive than blood sampling, especially in very sick premature neonates. Caffeine citrate-3 mg/kg, 15 mg/kg, or 30 mg/kg-was administered once daily for 7 days in a randomized, parallel design to 59 newborn, premature infants with an initial loading dose of twice the maintenance dose. Serum and saliva samples (131 pairs) were collected and assayed by high-performance liquid chromatography (HPLC) for caffeine content. Measurable caffeine concentrations in serum ranged from 0.28 to 93.3 mg/L and in saliva from 0.35 to 91.5 mg/L. The mean ratio of the saliva-to-serum concentrations was 0.924. There was no significant difference in precision between the serum and salivary data. The mean serum caffeine concentration was 29.9 mg/L, and the mean salivary concentration was 27.7 mg/L, indicating a small negative bias for saliva versus serum monitoring. Salivary caffeine concentration monitoring is a satisfactory alternative to blood sampling across a wide range of caffeine doses used to treat apnea.

Theophylline population pharmacokinetics from routine monitoring data in very premature infants with apnoea.

1. Theophylline is commonly used in neonatology for the treatment and prophylaxis of apnoea of prematurity, and during ventilator weaning. 2. NONMEM was used to study the population pharmacokinetics of intravenous and oral theophylline from retrospective drug monitoring data in 82 premature neonates, weighing < 1500 g at birth, and < or = 32 weeks gestational age. 3. Clearance (CL), volume of distribution (V), and oral bioavailability (F1) from liquid preparations were modelled alone, and under the influence of demographic and clinical covariates, assuming a 1-compartment model with first-order elimination. 4. The final population models with influential co-variates were as follows: CL (1h-1) = 0.0000123 *body weight (g) + 0.000377 *postnatal age (days); V (1) = 0.000937 *body weight (g); F = 0.918. 5. The CL was lower and V was higher than previously reported for less premature neonates, term babies, and older children. 6. Predictive performance of the population models was evaluated by Bayesian forecasting in a similar, but independent cohort of 30 infants. There was statistically insignificant bias and imprecision between measured and predicted serum theophylline concentrations. 7. Based on the validated population models, recommended maintenance theophylline dosages are provided for infants aged between 2 and 50 days, and weighing 700 to 2000 g.

Assessment of bioelectrical impedance for individualizing gentamicin therapy in neonates.

The use of bioelectrical impedance (BI) analysis as a non-invasive approach for individualizing gentamicin therapy in newborn infants has been investigated in a two phase study. In Phase I, 1/impedance and length were identified as statistically significant predictors of the distribution volume of gentamicin (Adj R2 = 0.78, CV = 12.42%), and length/impedance and post-conceptual age were predictors of total systemic clearance (Adj R2 = 0.83, CV = 14.5%), following the administration of 2.5 mg.kg-1 gentamicin to 17 neonates (gestational age (GA) 27 to 36 weeks). In a prospective validation of these relationships in an independent (Phase II) group of 27 infants (GA 26 to 41 weeks), predicted serum gentamicin concentrations were close to those achieved. Several instances of high prediction errors (predicted minus achieved levels) were observed in infants with known or suspected renal impairment and they caused significant (P < 0.05) perturbation in the bias and accuracy of the models. Daily BI measures over a four to five day period were able to detect individual changes in the fat-free body compartments, which were translated into alterations in gentamicin regimens. This simple, non-invasive and relatively inexpensive bedside technique provides a potentially valuable means to individualize gentamicin therapy without relying on the measurement of serum gentamicin concentration.