K.J.S. Anand

Halothane-morphine compared with high-dose sufentanil for anesthesia and postoperative analgesia in neonatal cardiac surgery

BACKGROUND Extreme hormonal and metabolic responses to stress are associated with increased morbidity and mortality in sick adults. We hypothesized that administering deep opioid anesthesia to critically ill neonates undergoing cardiac surgery would blunt their responses to stress and might improve clinical outcomes. METHODS In a randomized trial, 30 neonates were assigned to receive deep intraoperative anesthesia with high doses of sufentanil and postoperative infusions of opiates for 24 hours; 15 neonates were assigned to receive lighter anesthesia with halothane and morphine followed postoperatively by intermittent morphine and diazepam. Hormonal and metabolic responses to surgery were evaluated by assay of arterial blood samples obtained before, during, and after the operations. RESULTS The neonates who received deep anesthesia (with sufentanil) had significantly reduced responses of beta-endorphin, norepinephrine, epinephrine, glucagon, aldosterone, cortisol, and other steroid hormones; their insulin responses and ratios of insulin to glucagon were greater during the operation. The neonates who received lighter anesthesia (with halothane plus morphine) had more severe hyperglycemia and lactic acidemia during surgery and higher lactate and acetoacetate concentrations postoperatively (P less than 0.025). The group that received deep anesthesia had a decreased incidence of sepsis (P = 0.03), metabolic acidosis (P less than 0.01), and disseminated intravascular coagulation (P = 0.03) and fewer postoperative deaths (none of 30 given sufentanil vs. 4 of 15 given halothane plus morphine, (P less than 0.01). CONCLUSIONS In neonates undergoing cardiac surgery, the physiologic responses to stress are attenuated by deep anesthesia and postoperative analgesia with high doses of opioids. Deep anesthesia continued postoperatively may reduce the vulnerability of these neonates to complications and may reduce mortality.

Epidemiology and treatment of painful procedures in neonates in intensive care units.

CONTEXT Effective strategies to improve pain management in neonates require a clear understanding of the epidemiology and management of procedural pain. OBJECTIVE To report epidemiological data on neonatal pain collected from a geographically defined region, based on direct bedside observation of neonates. DESIGN, SETTING, AND PATIENTS Between September 2005 and January 2006, data on all painful and stressful procedures and corresponding analgesic therapy from the first 14 days of admission were prospectively collected within a 6-week period from 430 neonates admitted to tertiary care centers in the Paris region of France (11.3 millions inhabitants) for the Epidemiology of Procedural Pain in Neonates (EPIPPAIN) study. MAIN OUTCOME MEASURE Number of procedures considered painful or stressful by health personnel and corresponding analgesic therapy. RESULTS The mean (SD) gestational age and intensive care unit stay were 33.0 (4.6) weeks and 8.4 (4.6) calendar days, respectively. Neonates experienced 60,969 first-attempt procedures, with 42,413 (69.6%) painful and 18,556 (30.4%) stressful procedures; 11,546 supplemental attempts were performed during procedures including 10,366 (89.8%) for painful and 1180 (10.2%) for stressful procedures. Each neonate experienced a median of 115 (range, 4-613) procedures during the study period and 16 (range, 0-62) procedures per day of hospitalization. Of these, each neonate experienced a median of 75 (range, 3-364) painful procedures during the study period and 10 (range, 0-51) painful procedures per day of hospitalization. Of the 42,413 painful procedures, 2.1% were performed with pharmacological-only therapy; 18.2% with nonpharmacological-only interventions, 20.8% with pharmacological, nonpharmacological, or both types of therapy; and 79.2% without specific analgesia, and 34.2% were performed while the neonate was receiving concurrent analgesic or anesthetic infusions for other reasons. Prematurity, category of procedure, parental presence, surgery, daytime, and day of procedure after the first day of admission were associated with greater use of specific preprocedural analgesia, whereas mechanical ventilation, noninvasive ventilation and administration of nonspecific concurrent analgesia were associated with lower use of specific preprocedural analgesia. CONCLUSION During neonatal intensive care in the Paris region, large numbers of painful and stressful procedures were performed, the majority of which were not accompanied by analgesia.

Can Adverse Neonatal Experiences Alter Brain Development and Subsequent Behavior

Self-destructive behavior in current society promotes a search for psychobiological factors underlying this epidemic. Perinatal brain plasticity increases the vulnerability to early adverse experiences, thus leading to abnormal development and behavior. Although several epidemiological investigations have correlated perinatal and neonatal complications with abnormal adult behavior, our understanding of the underlying mechanisms remains rudimentary. Models of early experience, such as repetitive pain, sepsis, or maternal separation in rodents and other species have noted multiple alterations in the adult brain, correlated with specific behavioral phenotypes depending on the timing and nature of the insult. The mechanisms mediating such changes in the neonatal brain have remained largely unexplored. We propose that lack of N-methyl-D-aspartate (NMDA) receptor activity from maternal separation and sensory isolation leads to increased apoptosis in multiple areas of the immature brain. On the other hand, exposure to repetitive pain may cause excessive NMDA/excitatory amino acid activation resulting in excitotoxic damage to developing neurons. These changes promote two distinct behavioral phenotypes characterized by increased anxiety, altered pain sensitivity, stress disorders, hyperactivity/attention deficit disorder, leading to impaired social skills and patterns of self-destructive behavior. The clinical important of these mechanisms lies in the prevention of early insults, effective treatment of neonatal pain and stress, and perhaps the discovery of novel therapeutic approaches that limit neuronal excitotoxicity or apoptosis.

Effects of morphine analgesia in ventilated preterm neonates: primary outcomes from the NEOPAIN randomised trial

BACKGROUND Opioid analgesia is commonly used during neonatal intensive care. We undertook the Neurologic Outcomes and Pre-emptive Analgesia in Neonates (NEOPAIN) trial to investigate whether pre-emptive morphine analgesia decreases the rate of a composite primary outcome of neonatal death, severe intraventricular haemorrhage (IVH), and periventricular leucomalacia (PVL) in preterm neonates. METHODS Ventilated preterm neonates (n=898) from 16 centres were randomly assigned masked placebo (n=449) or morphine (n=449) infusions. After a loading dose (100 microg/kg), morphine infusions (23-26 weeks of gestation 10 microg kg(-1) h(-1); 27-29 weeks 20 microg kg(-1) h(-1); 30-32 weeks 30 microg kg(-1) h(-1)) were continued as long as clinically justified (maximum 14 days). Open-label morphine could be given on clinical judgment (placebo group 242/443 [54.6%], morphine group 202/446 [45.3%]). Analyses were by intention to treat. FINDINGS Baseline variables were similar in the randomised groups. The placebo and morphine groups had similar rates of the composite outcome (105/408 [26%] vs 115/419 [27%]), neonatal death (47/449 [11%] vs 58/449 [13%]), severe IVH (46/429 [11%] vs 55/411 [13%]), and PVL (34/367 [9%] vs 27/367 [7%]). For neonates who were not given open-label morphine, rates of the composite outcome (53/225 [24%] vs 27/179 [15%], p=0.0338) and severe IVH (19/219 [9%] vs 6/189 [3%], p=0.0209) were higher in the morphine group than the placebo group. Placebo-group neonates receiving open-label morphine had worse rates of the composite outcome than those not receiving open-label morphine (78/228 [34%] vs 27/179 [15%], p<0.0001). Morphine-group neonates receiving open-label morphine were more likely to develop severe IVH (36/190 [19%] vs 19/219 [9%], p=0.0024). INTERPRETATION Pre-emptive morphine infusions did not reduce the frequency of severe IVH, PVL, or death in ventilated preterm neonates, but intermittent boluses of open-label morphine were associated with an increased rate of the composite outcome. The morphine doses used in this study decrease clinical signs of pain but can cause significant adverse effects in ventilated preterm neonates.

Clinical Importance of Pain and Stress in Preterm Neonates

Clinical and laboratory investigations of neonatal pain suggest that preterm neonates have an increased sensitivity to pain and that acute painful stimuli lead to the development of prolonged periods of hyperalgesia. Non-noxious stimuli during these periods of hyperalgesia may expose preterm neonates to established or chronic pain. Acute physiologic changes caused by painful or stressful stimuli can be implicated as important factors in the causation or subsequent extension of early intraventricular hemorrhage (IVH) or the ischemic changes leading to periventricular leukomalacia (PVL). Therapeutic interventions that provide comfort/analgesia in preterm neonates were correlated with a decreased incidence of severe IVH. Long-term follow-up studies of preterm neonates may substantiate the preliminary data associating repetitive painful experiences with some of the neurobehavioral and developmental sequelae resulting from neonatal intensive care.

Long-Term Behavioral Effects of Repetitive Pain in Neonatal Rat Pups

Human preterm neonates are subjected to repetitive pain during neonatal intensive care. We hypothesized that exposure to repetitive neonatal pain may cause permanent or long-term changes because of the developmental plasticity of the immature brain. Neonatal rat pups were stimulated one, two, or four times each day from P0 to P7 with either needle prick (noxious groups N1, N2, N4) or cotton tip rub (tactile groups T1, T2, T4). In groups N2, N4, T2, T4 stimuli were applied to separate paws at hourly intervals;each paw was stimulated only once a day. Identical rearing occurred from P7 to P22 days. Pain thresholds were measured on P16, P22, and P65 (hot-plate test), and testing for defensive withdrawal, alcohol preference, air-puff startle, and social discrimination tests occurred during adulthood. Adult rats were exposed to a hot plate at 62 degrees C for 20 s, then sacrificed and perfused at 0 and 30 min after exposure. Fos expression in the somatosensory cortex was measured by immunocytochemistry. Weight gain in the N2 group was greater than the T2 group on P16 (p < 0.05) and P22 (p < 0.005); no differences occurred in the other groups. Decreased pain latencies were noted in the N4 group [5.0 +/- 1.0 s vs. 6.2 +/- 1.4 s on P16 (p < 0.05); 3.9 +/- 0.5 s vs. 5.5 +/- 1.6 s on P22 (p < 0.005)], indicating effects of repetitive neonatal pain on subsequent development of the pain system. As adults, N4 group rats showed an increased preference for alcohol (55 +/- 18% vs. 32 +/- 21%; p = 0.004); increased latency in exploratory and defensive withdrawal behavior (p < 0.05); and a prolonged chemosensory memory in the social discrimination test (p < 0.05). No significant differences occurred in corticosterone and ACTH levels following air-puff startle or in pain thresholds at P65 between N4 and T4 groups. Fos expression at 30 min after hot-plate exposure was significantly greater in all areas of the somatosensory cortex in the T4 group compared with the N4 group (p < 0.05), whereas no differences occurred just after exposure. These data suggest that repetitive pain in neonatal rat pups may lead to an altered development of the pain system associated with decreased pain thresholds during development. Increased plasticity of the neonatal brain may allow these and other changes in brain development to increase their vulnerability to stress disorders and anxiety-mediated adult behavior. Similar behavioral changes have been observed during the later childhood of expreterm neonates who were exposed to prolonged periods of neonatal intensive care.

Hormonal—Metabolic Stress Responses in Neonates Undergoing Cardiac Surgery

Hormonal and metabolic responses were measured in 15 neonates who underwent repair of complex congenital heart defects during a standardized anesthetic protocol. Four of the 15 neonates died postoperatively in the intensive care unit. Analysis of arterial plasma samples obtained before, during, and 24 h after surgery showed that plasma epinephrine, norepinephrine, cortisol, glucagon, and beta endorphin increased in all patients (P less than 0.05). Insulin levels increased only at the end of surgery but remained elevated for 24 h postoperatively (P less than 0.02). Intraoperative metabolic changes were characterized by hyperglycemia and lactic acidemia that persisted postoperatively. This pattern of neonatal stress responses is distinct from and more extreme than that seen in adult cardiac surgical patients. The four neonates who died postoperatively tended to have higher stress responses intra- and postoperatively despite having been indistinguishable from survivors by the usual clinical and hemodynamic criteria. These preliminary results suggest that neonatal hormonal and metabolic responses to cardiac surgical operations in neonates are extreme and are associated with a high hospital mortality rate.

Long-term effects of pain in infants

Pain and stress have been shown to induce significant physiological and behavioral reactions in newborn infants, even in those born prematurely. Infants who are born prematurely or seriously ill are commonly exposed to multiple painful and stressful events as part of their prolonged hospitalizations and required medical procedures. There is now evidence that these early events not only induce acute changes, but that permanent structural and functional changes may also result. This article reviews the growing body of evidence of likely long-term effects of early pain and stress on the human infant. It is hoped that a better understanding of this literature will promote more responsive and sensitive management of infants and young children during their encounters with the medical community and will ultimately facilitate the healthy growth and development of all children.

Vulnerability of the developing brain: Neuronal mechanisms

Despite the improved survival of tiny preterm neonates, their neurodevelopmental outcomes remain a cause for grave concern. The authors propose two primary mechanisms leading to enhanced neuronal cell death in the immature brain: (1) NMDA-mediated excitotoxicity resulting from repetitive or prolonged pain, and (2) enhanced naturally occurring neuronal apoptosis during early development due to multiple metabolic stresses or lack of social stimulation. The pattern and magnitude of abnormalities will depend on genetic variability as well as the timing, intensity, and duration of adverse environmental experiences. Thus, cumulative brain damage during infancy will finally lead to reductions in brain volume, abnormal behavioral and neuroendocrine regulation, and poor cognitive outcomes during childhood and adolescence. The public health and economic importance of preventing or ameliorating the subtle brain damage caused by these mechanisms cannot be overestimated. This certainly justifies concerted efforts by neuroscientists and clinicians to investigate the mechanisms underlying early neuronal injury, to minimize the impact of adverse experiences and environmental factors in neonates, and to develop novel therapeutic strategies for improving the cognitive and behavioral outcomes of ex-preterm neonates.

Morphine Does Not Provide Adequate Analgesia for Acute Procedural Pain Among Preterm Neonates

Background. Morphine alleviates prolonged pain, reduces behavioral and hormonal stress responses induced by surgery among term neonates, and improves ventilator synchrony and sedation among ventilated preterm neonates, but its analgesic effects on the acute pain caused by invasive procedures remain unclear. Objective. To investigate the analgesic efficacy of intravenously administered morphine on heel stick-induced acute pain among preterm neonates. Design. This study was nested within a prospective, randomized, double-blind, multicenter, placebo-controlled trial (the NEOPAIN Trial). Setting. A tertiary-care NICU in a teaching hospital. Participants. Forty-two preterm neonates undergoing ventilation. Interventions. Neonates were randomized to either the morphine (loading dose of 100 μg/kg, followed by infusions of 10–30 μg/kg per hour according to gestation, N = 21) or placebo (5% dextrose infusions, N = 21) group. Pain responses to 3 heel sticks were evaluated, ie, before the loading dose (T1), 2 to 3 hours after the loading dose (T2), and 20 to 28 hours after the loading dose (T3). Main Outcomes Measures. Pain was assessed with the Douleur Aiguë Nouveau-né (DAN) scale (behavioral pain scale) and the Premature Infant Pain Profile (PIPP) (multidimensional pain scale); plasma morphine levels were measured at T3. Results. Infants in the placebo and morphine groups had similar gestational ages (mean ± SD: 27.2 ± 1.7 vs 27.3 ± 1.8 weeks) and birth weights (972 ± 270 vs 947 ± 269 g). Mean ± SD DAN pain scores at T1, T2, and T3 were 4.8 ± 4.0, 4.6 ± 2.9, and 4.7 ± 3.6, respectively, for the placebo group and 4.5 ± 3.8, 4.4 ± 3.7, and 3.1 ± 3.4 for the morphine group. The within-group factor (pain at T1, T2, and T3) was not statistically different over time. The between-group analysis (infants receiving placebo versus those receiving morphine) showed no significant differences. Mean ± SD PIPP pain scores at T1, T2, and T3 were 11.5 ± 4.8, 11.1 ± 3.7, and 9.1 ± 4.0, respectively, for the placebo group and 10.0 ± 3.6, 8.8 ± 4.9, and 7.8 ± 3.6 for the morphine group. The within-group factor was statistically different over time. The between-group analysis showed no significant differences. Mean ± SD plasma morphine levels at T3 were 0.44 ± 1.79 ng/mL and 63.36 ± 33.35 ng/mL for the placebo and morphine groups, respectively. There was no correlation between plasma morphine levels and pain scores at T3 (DAN, R = −0.05; PIPP, R = −0.02). Conclusions. Despite its routine use in the NICU, morphine given as a loading dose followed by continuous intravenous infusions does not appear to provide adequate analgesia for the acute pain caused by invasive procedures among ventilated preterm neonates.