Richard W. Hall

Ketamine reduces the cell death following inflammatory pain in newborn rat brain.

Premature infants experience untreated repetitive pain that may alter their brain development. Effects of ketamine and repetitive pain on cellular death and subsequent behavior were studied in neonatal rats. Rat pups were randomized to undisturbed controls (C), 4% formalin injection (F), ketamine alone (K, 5 mg/kg) or formalin plus ketamine (KF) and were assessed for neuroactivation with Fos protein, cellular death with FluoroJade-B, cognition with the radial arm maze, and pain thresholds with the hot-plate. Greater Fos expression and cell death occurred in F vs. C groups in defined brain areas at 1 and 4 h in F compared with other groups. Cell death was accentuated 3.3-fold in cortical areas and 1.6-fold in subcortical areas in the F compared with the C group following repetitive pain and sacrifice 18–20 h later. These effects were ameliorated by ketamine. Compared with the F group, all other groups demonstrated greater exploratory and rearing behaviors and decreased time for bait consumption at 1-h and 3-h intervals. Significantly greater thermal pain latencies occurred in the KF and F groups. Repetitive neonatal pain accentuates neuronal excitation and cell death in developmentally regulated cortical and subcortical areas, which decreases the acquisition of visual-spatial clues, short-term and long-term memory, and increases pain latencies. Ketamine analgesia mitigates most of these effects.

Morphine, Hypotension, and Adverse Outcomes Among Preterm Neonates: Who’s to Blame? Secondary Results From the NEOPAIN Trial

Objectives. Hypotension occurs commonly among preterm neonates, but its cause and consequences remain unclear. Secondary data analyses from the NEOPAIN trial identified the clinical factors associated with hypotension and examined the contributions of morphine treatment or hypotension to severe intraventricular hemorrhage (IVH) (grades 3 and 4), any IVH (grades 1–4), or death. Methods. In the NEOPAIN trial, 898 ventilated neonates between 23 and 32 weeks of gestation were enrolled, with equal numbers randomized to receive masked morphine or placebo infusions. Additional doses of open-label morphine were administered as necessary by medical staff members. IVH was diagnosed with centralized readings of early and late cranial ultrasonograms. Hypotension was assessed before study drug infusion, during the loading dose, and at 24 and 72 hours during study drug infusion. Logistic regression analyses with stepdown elimination identified the predictor factors associated with the hypotension, severe IVH, any IVH, or death outcomes at each time point. Results. Hypotension was associated with 23 to 26 weeks of gestation, morphine infusions, severity of illness, additional morphine doses, and prior hypotension. Severe IVH was associated with shorter gestation, higher Clinical Risk Index for Babies scores, no prenatal steroids, pulmonary hemorrhage, hypotension before the loading dose, and morphine doses before intubation and at 25 to 72 hours. Neonatal deaths were associated with 23 to 26 weeks of gestation, higher Clinical Risk Index for Babies scores, pulmonary hemorrhage, patent ductus arteriosus, thrombocytopenia, and hypotension before the loading dose. Morphine infusions were not a significant factor in logistic models for severe IVH, any IVH, or death. Conclusions. Preemptive morphine infusions, additional morphine, and lower gestational age were associated with hypotension among preterm neonates. Severe IVH, any IVH, and death were associated with preexisting hypotension, but morphine therapy did not contribute to these outcomes. Morphine infusions, although they cause hypotension, can be used safely for most preterm neonates but should be used cautiously for 23- to 26-week neonates and those with preexisting hypotension.

Morphine pharmacokinetics and pharmacodynamics in preterm and term neonates: secondary results from the NEOPAIN trial

BACKGROUND Relationships between plasma morphine concentrations and neonatal responses to endotracheal tube (ETT) suctioning are unknown in preterm neonates. METHODS Ventilated preterm neonates (n=898) from 16 centres were randomly assigned to placebo (n=449) or morphine (n=449). After an i.v. loading dose (100 microg kg(-1)), morphine infusions [23-26 weeks postmenstrual age (PMA) 10 microg kg(-1) h(-1); 27-29 weeks 20 microg kg(-1) h(-1); and 30-32 weeks 30 microg kg(-1) h(-1)] were established for a maximum of 14 days. Open-label morphine (20-100 microg kg(-1)) was given for pain or agitation. Morphine assay and neonatal response to ETT suctioning was measured at 20-28 and 70-76 h after starting the drug infusion and at 10-14 h after discontinuation of the study drug. The concentration-effect response was investigated using non-linear mixed effects models. RESULTS A total of 5119 data points (1598 measured morphine concentrations and 3521 effect measures) were available from 875 neonates for analysis. Clearance was 50% that of the mature value at 54.2 weeks PMA (CLmat(50)) and increased from 2.05 litre h(-1) 70 kg(-1) at 24 weeks PMA to 6.04 litre h(-1) 70 kg(-1) at 32 weeks PMA. The volume of distribution in preterm neonates was 190 litre 70 kg(-1) (CV 51%) and did not change with age. There was no relationship between morphine concentrations (range 0-440 microg litre(-1)) and heart rate changes associated with ETT suctioning or with the Premature Infant Pain Profile. CONCLUSIONS A sigmoid curve describing maturation of morphine clearance is moved to the right in preterm neonates and volume of distribution is increased compared with term neonates. Morphine does not alter the neonatal response to ETT suctioning.

Late Preterm Infants: Birth Outcomes and Health Care Utilization in the First Year

OBJECTIVE: To distinguish the effects of late preterm birth from the complications associated with the causes of delivery timing, this study used propensity score–matching methods on a statewide database that contains information on both mothers and infants. METHODS: Data for this study came from Arkansas Medicaid claims data linked to state birth certificate data for the years 2001 through 2005. We excluded all multiple births, infants with birth defects, and infants at <33 weeks of gestation. Late preterm infants (LPIs) (34 to 36 weeks of gestation) were matched with term infants (37–42 weeks of gestation) according to propensity scores, on the basis of infant, maternal, and clinical characteristics. RESULTS: A total of 5188 LPIs were matched successfully with 15303 term infants. LPIs had increased odds of poor outcomes during their birth hospitalization, including a need for mechanical ventilation (adjusted odds ratio [aOR]: 1.31 [95% confidence interval [CI]: 1.01–1.68]), respiratory distress syndrome (aOR: 2.84 [95% CI: 2.33–3.45]), and hypoglycemia (aOR: 1.60 [95% CI: 1.26–2.03]). Outpatient and inpatient Medicaid expenditures in the first year were both modestly higher (outpatient, adjusted marginal effect:

Pain management in newborns.

108 [95% CI:

Ketamine analgesia for inflammatory pain in neonatal rats: a factorial randomized trial examining long-term effects

58–

Effect of inborn versus outborn delivery on clinical outcomes in ventilated preterm neonates: secondary results from the NEOPAIN trial.

158]; inpatient,

Love, pain, and intensive care.

597 [95% CI:

Telemedicine collaboration improves perinatal regionalization and lowers statewide infant mortality.

528–

Prolonged morphine exposure in utero causes fetal and placental vasoconstriction: A case report

666]) for LPIs. CONCLUSIONS: LPIs are at increased risk of poor health-related outcomes during their birth hospitalization and of increased health care utilization during their first year.