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C D Kurth

Publications and source records attributed to C D Kurth.

At least 37 records · Page 2Linked to original sources
PubMed1998

Comparison of pH-stat and alpha-stat cardiopulmonary bypass on cerebral oxygenation and blood flow in relation to hypothermic circulatory arrest in piglets.

BACKGROUND: Deep hypothermic circulatory arrest is used in neonatal cardiac surgery. Recent work has suggested improved neurologic recovery after deep hypothermic arrest with pH-stat cardiopulmonary bypass (CPB) compared with alpha-stat CPB. This study examined cortical oxygen saturation (ScO2), cortical blood flow (CBF), and cortical physiologic recovery in relation to deep hypothermic arrest with alpha-stat or pH-stat CPB. METHODS: Sixteen piglets were cooled with pH-stat or alpha-stat CPB to 19 degrees C (cortex) and subjected to 60 min of circulatory arrest, followed by CPB reperfusion and rewarming and separation from CPB. Near infrared spectroscopy and laser Doppler flowmetry were used to monitor ScO2 and CBF. Cortical physiologic recovery was assessed 2 h after the piglets were separated from CPB by cortical adenosine triphosphate concentrations, cortical water content, CBF, and ScO2. RESULTS: During CPB cooling, ScO2 increased more with pH-stat than with alpha-stat bypass (123 +/- 33% vs. 80 +/- 25%); superficial and deep CBF were also greater with pH-stat than with alpha-stat bypass (22 +/- 25% vs. -56 +/- 22%, 3 +/- 19% vs. -29 +/- 28%). During arrest, ScO2 half-life was greater with pH-stat than with alpha-stat bypass (10 +/- 2 min vs. 7 +/- 2 min), and cortical oxygen consumption lasted longer with pH-stat than with alpha-stat bypass (36 +/- 8 min vs. 25 +/- 8 min). During CPB reperfusion, superficial and deep CBF were less with alpha-stat than with pH-stat bypass (-40 +/- 22% vs. 10 +/- 39%, -38 +/- 28% vs. 5 +/- 28%). After CPB, deep cortical adenosine triphosphate and CBF were less with alpha-stat than with pH-stat bypass (11 +/- 6 pmole/mg vs. 17 +/- 8 pmole/mg, -24 +/- 16% vs. 16 +/- 32%); cortical water content was greater with alpha-stat than with pH-stat bypass (superficial: 82.4 +/- 0.3% vs. 81.8 +/- 1%, deep: 79.1 +/- 2% vs. 78 +/- 1.6%). CONCLUSIONS: Cortical deoxygenation during hypothermic arrest was slower after pH-stat CPB. pH-stat bypass increased the prearrest ScO2 and arrest ScO2 half-life, to increase the cortical oxygen supply and slow cortical oxygen consumption. Improved cortical physiologic recovery after hypothermic arrest was suggested with pH-stat management.

Animals↗
PubMed1997

Brain cooling efficiency with pH-stat and alpha-stat cardiopulmonary bypass in newborn pigs.

BACKGROUND: For infant cardiac surgery, recent studies suggest improved neurological outcome after deep hypothermic circulatory arrest when pH-stat cardiopulmonary bypass is used compared with alpha-stat cardiopulmonary bypass. The pH-stat method is hypothesized to protect the brain through improved cooling and/or rewarming. We examined brain cooling and rewarming during pH-stat and alpha-stat cardiopulmonary bypass in 12 newborn pigs. METHODS AND RESULTS: Microthermistors were inserted into the caudate and cortical gray and white matter, and a cranial window was created to map neocortical temperature gradients by using infrared imaging. Piglets were cooled with pH-stat or alpha-stat cardiopulmonary bypass until all brain regions were less than 20 degrees C; then they were subjected to 60 minutes of circulatory arrest, and afterward, rewarmed with cardiopulmonary bypass. During cardiopulmonary bypass cooling, cortical gray and white matter and caudate temperatures were up to 5 degrees C less in pH-stat than in alpha-stat (P<.05), although after 10 minutes of cooling, only cortical white matter temperature remained significantly less in pH-stat. Neocortical thermal gradients during cardiopulmonary bypass cooling were greater in pH-stat versus alpha-stat during the initial 8 minutes (4 degrees C to 5 degrees C versus 2 degrees C to 3 degrees C, P<.01) but were less by 18 to 20 minutes (0.9 degrees C versus 1.7 degrees C, P<.01). Cardiopulmonary bypass cooling time to less than 20 degrees C was shorter for pH-stat than for alpha-stat in cortical gray matter (14 versus 17 minutes, P<.05) and cortical white matter (17 versus 23 minutes, P<.001) but not in caudate (13 versus 16 minutes, P=NS). Cooling time to less than 1 degrees C neocortical thermal gradient was shorter in pH-stat than in alpha-stat (15 versus 23 minutes, P<.001). During rewarming, regional brain temperatures and neocortical thermal gradients were not different between groups. CONCLUSIONS: pH-stat improves brain cooling efficiency during cardiopulmonary bypass because all regions cooled more rapidly, especially cortical white matter, and less time was required to achieve uniform cerebral deep hypothermia. pH-stat and alpha-stat cardiopulmonary bypass rewarm the brain similarly after deep hypothermic arrest.

Animals↗
PubMed1997

Cerebral blood flow regulation in neonatal rabbits is altered by chronic cocaine administration.

Maternal cocaine abuse has several deleterious effects in the newborn, including perinatal asphyxia, hypoxia, and hypercapnia. We hypothesized that chronic cocaine exposure during development may alter cerebral blood flow (CBF) regulation. We studied 16 neonatal rabbits that had received cocaine (20 mg/kg, i.p. b.i.d.) or saline since birth. Changes in CBF were measured by laser doppler flowmetry before (baseline), and during hypercapnia (FiCO2 = 7.5%), hypoxia (FiO2 = 12%), and asphyxia (apnea for 1 min). During hypercapnia, CBF increased less in cocaine than in control animals (28 +/- 3% vs. 69 +/- 10%, P < 0.05). During hypoxia, CBF increased similarly in both groups. During reventilation after asphyxia, CBF increased more in cocaine than in control animals (391 +/- 52% vs. 225 +/- 43%, P < 0.05). Chronic cocaine exposure during brain development appears to alter CBF regulation to hypercapnia and asphyxia, which may put the drug exposed newborn at risk for neurologic injury around birth.

Animals↗
PubMed1997

Altered brain oxygen extraction with hypoxia and hypotension following deep hypothermic circulatory arrest.

The utilization of cardiopulmonary bypass in neonates, infants and children often requires the use of deep hypothermia at 18 degrees C with occasional periods of circulatory arrest. Thus, marked physiologic extremes of temperature and perfusion are induced. The safety of these techniques appears to be related to the reduction of metabolism, particularly cerebral metabolism. We studied the effect of deep hypothermic circulatory arrest and cardiopulmonary bypass on brain oxygenation using near-infrared spectroscopy. After hypothermic arrest, brain oxygen extraction during severe hypoxia and severe hypotension is diminished. However, these responses remain intact after cardiopulmonary bypass. Additionally, cardiopulmonary bypass, rather than deep hypothermic circulatory arrest alters the cerebral oxygen response to hypercapnia. The primary goal of studying alteration of brain oxygenation during cardiopulmonary bypass and deep hypothermic circulatory arrest is to improve our understanding of the association between these methods and perturbations in hemodynamics and ventilation, so that effective brain protection strategies can be developed.

Animals↗
PubMed1997

Intrapartum airway management for giant fetal neck masses: the EXIT (ex utero intrapartum treatment) procedure.

OBJECTIVE: Our goal was to review our experience with the EXIT (ex utero intrapartum treatment) procedure in the management of five cases with life-threatening fetal neck masses. STUDY DESIGN: We present a retrospective review of prenatal presentation and course, diagnostic accuracy of imaging studies, intraoperative management, complications, and outcomes. RESULTS: Polyhydramnios was the initial presenting symptom in three of five fetuses with a mean gestational age of 25 +/- 6 weeks. Preterm labor occurred in two patients. Fetal magnetic resonance imaging provided accurate diagnosis in all four cases whereas conventional ultrasonography led to the diagnosis in four of five cases. The mean duration of EXIT was 28 +/- 22 minutes. The mean venous cord blood gas values were pH 7.22 +/- 0.05, PCO2 61 +/- 11 mm Hg, and PO2 42 +/- 8 mm Hg. In four of five cases an airway was successfully secured. CONCLUSIONS: The EXIT procedure provides up to 1 hour of good uteroplacental support and is the procedure of choice to secure an airway in the fetus with a giant neck mass.

Airway Obstruction↗
PubMed1997

Cerebral oxygenation during cardiopulmonary bypass in children.

OBJECTIVE: Previous work has found cerebral oxygen extraction to decrease during hypothermic cardiopulmonary bypass in children. To elucidate cardiopulmonary bypass factors controlling cerebral oxygen extraction, we examined the effect of perfusate temperature, pump flow rate, and hematocrit value on cerebral hemoglobin-oxygen saturation as measured by near infrared spectroscopy. METHODS: Forty children less than 7 years of age scheduled for cardiac operations with continuous cardiopulmonary bypass were randomly assigned to warm bypass, hypothermic bypass, hypothermic low-flow bypass, or hypothermic low-hematocrit bypass. For warm bypass, arterial perfusate was 37 degrees C, hematocrit value 23%, and pump flow 150 ml/kg per minute. Hypothermic bypass differed from warm bypass only in initial perfusate temperature (22 degrees C); hypothermic low-flow bypass and low-hematocrit bypass differed from hypothermic bypass only in pump flow (75 ml/kg per minute) and hematocrit value (16%), respectively. Cerebral oxygen saturation was recorded before bypass (baseline), during bypass, and for 15 minutes after bypass had been discontinued. RESULTS: In the warm bypass group, cerebral oxygen saturation remained at baseline levels during and after bypass. In the hypothermic bypass group, cerebral oxygen saturation increased 20% +/- 2% during bypass cooling (p < 0.001), returned to baseline during bypass rewarming, and remained at baseline after bypass. In the hypothermic low-flow and hypothermic low-hematocrit bypass groups, cerebral oxygen saturation remained at baseline levels during bypass but increased 6% +/- 2% (p = 0.05) and 10% +/- 2% (p < 0.03), respectively, after bypass was discontinued. CONCLUSIONS: In children, cortical oxygen extraction is maintained during warm cardiopulmonary bypass at full flow and moderate hemodilution. Bypass cooling can decrease cortical oxygen extraction but requires a certain pump flow and hematocrit value to do so. Low-hematocrit hypothermic bypass and low-flow hypothermic bypass can also alter cortical oxygen extraction after discontinuation of cardiopulmonary bypass.

Brain↗
PubMed1997

Cerebral hemoglobin and optical pathlength influence near-infrared spectroscopy measurement of cerebral oxygen saturation.

Near-infrared spectroscopy (NIRS) is a noninvasive optical technique to monitor cerebral oxygen saturation at the bedside. Despite its applicability, NIRS has had limited clinical use because of concerns about accuracy, noted by intersubject variability in slope and intercept of the line between NIRS- and weighted-average arterial-cerebrovenous saturation (SMO2). This study evaluated transcranial optical pathlength and cerebral hemoglobin concentration as sources for this intersubject variability. Experiments were performed in an in vitro brain model and in piglets. Optical pathlength and cerebral hemoglobin concentration were measured by time-resolved spectroscopy (TRS). NIRS and TRS were recorded in the model, as perfusate blood saturation was varied (0%-100%) at several hemoglobin concentrations, and in piglets, as SMO2 was varied (15%-90%) before and after hemodilution. In the model, hemoglobin concentration significantly altered the NIRS versus blood saturation line slope and intercept, as well as optical pathlength. In piglets (before hemodilution), there was significant intersubject variability in NIRS versus SMO2 line slope (0.73-1.4) and intercept (-24 to 36) and in transcranial optical pathlength (13.4-16 cm) and cerebral hemoglobin concentration (0.58-1.1 g/dL). By adjusting the NIRS algorithm with optical pathlength or cerebral hemoglobin measurements, intersubject variability in slope (0.9-1.2) and intercept (-9 to 18) decreased significantly. Hemodilution significantly changed NIRS versus SMO2 line slope and intercept, as well as transcranial optical pathlength and cerebral hemoglobin concentration (before versus after hemodilution: slope 0.9 vs 0.78, intercept 13 vs 19, pathlength 13.9 vs 15.6 cm, cerebral hemoglobin 0.98 vs 0.73 g/dL). By adjusting the NIRS algorithm with the cerebral hemoglobin measurements, slope and intercept remained unchanged by hemodilution. These data indicate that intersubject variability in NIRS originates, in part, from biologic variations in transcranial optical pathlength and cerebral hemoglobin concentration. Instruments to account for these factors may improve NIRS cerebral oxygen saturation measurements.

Animals↗
PubMed1996

Effect of chronic cocaine exposure on carotid artery reactivity in neonatal rabbits.

Chronic cocaine abuse by pregnant women results in chronic neonatal drug exposure. In adults, chronic cocaine use alters neurotransmitter concentrations and receptor dose-response relationships. Similar changes may also occur in the neonatal cerebrovasculature after in utero cocaine exposure. This study examined the effect of chronic cocaine exposure on internal carotid artery reactivity to norepinephrine, serotonin, acetylcholine, sodium nitroprusside, adenosine, and cocaine in neonatal rabbits. Internal carotid artery rings were isolated from 16 to 20 day old rabbits that had received cocaine (20 mg/kg IP BID, n = 8) or saline (n = 8) from 5 days of age and were studied in organ baths using standard in vitro techniques. Chronic treatment with cocaine decreased the half-maximal relaxant response (ED50) to adenosine (control 6.9 +/- 1.8 vs cocaine 3.5 +/- 0.99 microM, p = 0.05). The half-maximal contractile responses (EC50) to norepinephrine and serotonin and the half-maximal relaxant responses (ED50) to acetylcholine and sodium nitroprusside were similar between groups. The threshold concentration of cocaine that induced vessel contraction was altered by chronic cocaine exposure (control group 10(-6) M vs chronic cocaine group 10(-4) M). We conclude that chronic cocaine exposure sensitizes carotid arteries to the relaxant effects of adenosine. In addition, chronic cocaine exposure desensitizes carotid arteries to the contractile effects of acute cocaine. These vasoreactivity changes may underlie altered cerebrovascular responses to asphyxia and play a role in the pathogenesis of postnatally acquired brain injury in critically ill "crack" babies.

Acetylcholine↗
PubMed1996

Hypertonic saline improves brain resuscitation in a pediatric model of head injury and hemorrhagic shock.

INTRODUCTION: Brain injury accompanied by hypovolemic shock is a frequent cause of death in multiply injured children. Hypertonic saline (HTS) has been shown to return hemodynamics to normal in adult models, without increasing intracranial pressure (ICP) as seen with crystalloids. To assess fluid resuscitation, the authors evaluated HTS versus lactated Ringer's solution (LR) with respect to hemodynamics and cerebrovascular hemoglobin oxygen saturation (Sco2) in anesthetized, head-injured, 1-month-old piglets. METHODS: Group 1 (n = 6) was studied for 3.5 hours after a cryogenic brain injury and no shock. Groups 2 and 3 had cryogenic brain injury followed by hemorrhagic shock, in which mean arterial pressure (MAP) was reduced to 40 to 50 mm Hg and maintained for 30 minutes. Group 2 (n = 5) was then resuscitated with 1 mL of 7.5% HTS per 1 mL of blood loss. Group 3 (n = 6) was resuscitated with 3 mL of LR per 1 mL of blood loss. Sco2 was determined by near-infrared spectroscopy in the injured region of the brain. All data were analyzed using analysis of variance with repeated measures. RESULTS: MAP, ICP, temperature, serum sodium, and cardiac output (CO) were similar in all groups during baseline and between groups 2 and 3 during shock. After resuscitation, MAP, CO, and core temperature were similar in all three groups, and serum sodium was increased in the HTS group (by 29%). Sco2 increased transiently after cryogenic injury in all groups, then gradually decreased to below baseline. After shock, Sco2 decreased precipitously in group 2 and 3. After resuscitation, Sco2 was different in the two resuscitation groups, increasing in the HTS group, above baseline values, but remaining below baseline values in the LR group (P < .002). ICP was lowered by HTS resuscitation and increased by LR resuscitation (P < .002) CONCLUSION: In our model of head injury and shock, resuscitation with either HTS or LR restored MAP and CO to control levels. However, during shock, the injured brain was severely deoxygenated, and administration of HTS restored cerebral oxygenation whereas LR did not, reflecting improved cerebral resuscitation by HTS without elevating ICP. The data suggest that HTS is a better resuscitation fluid than LR in head-injured children with hemorrhagic shock.

Animals↗
PubMed1996

Effect of dopamine antagonism on the behavioral and hemodynamic responses to cocaine in piglets.

Cocaine (1.5 mg/kg i.v.) was administered to awake newborn piglets that were pretreated with either intravenous saline (placebo) or SCH23390, a dopamine antagonist, to study dopamine's role in cocaine's vascular and behavioral actions. In the placebo group, cocaine increased the locomotor activity and cerebellar and cardiac blood flow (31 +/- 36 and 72 +/- 66%), but decreased choroid plexus and renal blood flow (47 +/- 23 and 18 +/- 19%). In the SCH23390-treated group, cocaine did not affect organ blood flow or locomotor activity. Cocaine transiently increased the mean arterial blood pressure in both groups (10 +/- 7 and 18 +/- 13%). These data indicate that the behavioral and blood flow responses to cocaine in cerebellum, choroid plexus, heart, and kidneys are mediated by dopamine, whereas the arterial pressor response to cocaine is not.

Animals↗
PubMed1995

Transcranial optical path length in infants by near-infrared phase-shift spectroscopy.

BACKGROUND: Near-infrared spectroscopy (NIRS) is an emerging technique for noninvasive, bedside monitoring of cerebral oxygenation and blood flow. Traditionally, it has relied on the Beer's Law relationship in which the concentration of light-absorbing oxygen-carrying pigments is proportional to their light absorbance, and inversely proportional to an optical path length (a measure of the distance traveled by photons passing through the tissue). In practice, NIRS has been based upon assumptions that mean transcranial optical path length, the average optical path length for a given patient, is constant among patients and independent of the wavelength of light used. OBJECTIVE: The objective of our study was to measure mean optical transcranial path length in infants as a step in allowing quantitation of cerebral oxygenation. METHODS: We measured mean transcranial optical path length in 34 infants, aged 1 day to 3 years, using amplitude-modulated phase-shift spectroscopy at 754 nm and 816 nm. Optical transcranial path lengths (mean +/- SEM) were 8.6 +/- 0.9 cm, 11.1 +/- 0.9 cm, and 11.3 +/- 0.9 cm at 754 nm, and 8.8 +/- 0.9 cm, 11.2 +/- 0.8 cm, and 11.1 +/- 0.9 cm at 816 nm, using emitter-detector separations of 1.8, 2.5, and 3.0 cm, respectively. Optical path length increased as emitter-detector separation, head circumference, or age increased. Variance in the ratio of mean optical path lengths at the two different wavelengths exceeded that accounted for by variation in repeated measures alone (p < 0.001), suggesting that optical path length is also not independent of wavelength. CONCLUSIONS: NIRS instrument emitter-detector geometry, subject age, head size, and wavelength used each influence optical path length. Quantitative NIRS measurements in clinical use may require concurrent measurement of both absorbance and optical path length at each wavelength, or use of newer measures that are not based upon Beer's Law assumptions.

Child, Preschool↗
PubMed1995

A dynamic phantom brain model for near-infrared spectroscopy.

This report describes the construction, fluid dynamics and optical properties of an in vitro model of the neonatal brain for testing near-infrared spectroscopy (NIRS) instruments. The brain model is a solid plastic structure containing a vascular network perfused with blood equilibrated with O2, N2 and CO2 in a closed circuit. The oxygenation state and haemoglobin concentration of the perfusate can be regulated and measured with a co-oximeter, providing a means to compare NIRS measurements of oxy-, deoxy- and total haemoglobin concentrations and haemoglobin O2 directly with a validated standard method. Fluid dynamic experiments revealed that the model's vasculature remains stable over time with minimal haemolysis. The model's optical properties were characterized by time-resolved and continuous wave NIRS between 670 and 850 nm as perfusate saturation was varied in the range 0-100%. Optical properties of the neonatal piglet brain were also determined by similar methods. No significant differences were found between the model and piglet brain in absorption coefficients, reduced scattering coefficients and optical pathlengths, indicating that the model optically simulates the piglet brain over a wide range of oxygenation states. These results demonstrate the potential utility of this dynamic phantom brain for testing NIRS instruments for accuracy and reliability.

Animals↗
PubMed1995

Cerebral oxygenation during pediatric cardiac surgery using deep hypothermic circulatory arrest.

BACKGROUND: Deep hypothermic circulatory arrest is a widely used technique in pediatric cardiac surgery that carries a risk of neurologic injury. Previous work in neonates identified distinct changes in cerebral oxygenation during surgery. This study sought to determine whether the intraoperative changes in cerebral oxygenation vary between neonates, infants, and children and whether the oxygenation changes are associated with postoperative cerebral dysfunction. METHODS: The study included eight neonates, ten infants, and eight children without preexisting neurologic disease. Cerebrovascular hemoglobin oxygen saturation (SCO2), an index of brain oxygenation, was monitored intraoperatively by near-infrared spectroscopy. Body temperature was reduced to 15 degrees C during cardiopulmonary bypass (CPB) before commencing circulatory arrest. Postoperative neurologic status was judged as normal or abnormal (seizures, stroke, coma). RESULTS: Relative to preoperative levels, the age groups experienced similar changes in SCO2 during surgery: SCO2 increased 30 +/- 4% during deep hypothermic CPB, it decreased 62 +/- 5% by the end of arrest, and it increased 20 +/- 5% during CPB recirculation (all P < 0.001); after rewarming and removal of CPB, SCO2 returned to preoperative levels. During arrest, the half-life of SCO2 was 9 +/- 1 min in neonates, 6 +/- 1 min in infants, and 4 +/- 1 min in children (P < 0.001). Postoperative neurologic status was abnormal in three (12%) patients. The SCO2 increase during deep hypothermic CPB was less in these patients than in the remaining study population (3 +/- 2% versus 33 +/- 4%, P < 0.001). There were no other significant SCO2 differences between outcome groups. CONCLUSIONS: Brain oxygenation changed at distinct points during surgery in all ages, reflecting fundamental cerebral responses to hypothermic CPB, ischemia, and reperfusion. However, the changes in SCO2 half-life with age reflect developmental differences in the rate of cerebral oxygen utilization during arrest, consistent with experimental work in animals. Certain intraoperative cerebral oxygenation patterns may be associated with postoperative cerebral dysfunction and require further study.

Aging↗
PubMed1995

Postoperative apnea in former preterm infants after inguinal herniorrhaphy. A combined analysis.

BACKGROUND: Controversy exists as to the risk for postoperative apnea in former preterm infants. The conclusions of published studies are limited by the small number of patients. METHODS: The original data from eight prospective studies were subject to a combined analysis. Only patients having inguinal herniorrhaphy under general anesthesia were included; patients receiving caffeine, regional anesthesia, or undergoing other surgical procedures were excluded. A uniform definition for apnea was used for all patients. Eleven risk factors were examined: gestational age, postconceptual age, birth weight, history of respiratory distress syndrome, bronchopulmonary dysplasia, neonatal apnea, necrotizing enterocolitis, ongoing apnea, anemia, and use of opioids or nondepolarizing muscle relaxants. RESULTS: Two hundred fifty-five of 384 patients from eight studies at four institutions fulfilled study criteria. There was significant variation in apnea rates and the location of apnea (recovery room and postrecovery room) between institutions (P < 0.001). There was considerable variation in the duration and type of monitoring, definitions of apnea, and availability of historical information. The incidence of detected apnea was greater when continuous recording devices were used compared to standard impedance pneumography with alarms or nursing observations. Despite these limitations, it was determined that: (1) apnea was strongly and inversely related to both gestational age (P = 0.0005) and postconceptual age (P < 0.0001); (2) an associated risk factor was continuing apnea at home; (3) small-for-gestational-age infants seemed to be somewhat protected from apnea compared to appropriate- and large-for-gestational-age infants; (4) anemia was a significant risk factor, particularly for patients > 43 weeks' postconceptual age; (5) a relationship to apnea with history of necrotizing enterocolitis, neonatal apnea, respiratory distress syndrome, bronchopulmonary dysplasia, or operative use of opioids and/or muscle relaxants could not be demonstrated. CONCLUSIONS: The analysis suggests that, if it is assumed that the statistical models used are equally valid over the full range of ages considered and that the average rate of apnea reported across the studies analyzed is accurate and representative of actual rates in all institutions, the probability of apnea in nonanemic infants free of recovery-room apnea is not less than 5%, with 95% statistical confidence until postconceptual age was 48 weeks with gestational age 35 weeks. This risk is not less than 1%, with 95% statistical confidence, for that same subset of infants, until postconceptual age was 56 weeks with gestational age 32 weeks or postconceptual age was 54 weeks and gestational age 35 weeks. Older infants with apnea in the recovery room or anemia also should be admitted and monitored. The data do not allow prediction with confidence up to what age this precaution should continue to be taken for infants with anemia. The data were insufficient to allow recommendations regarding how long infants should be observed in recovery. There is additional uncertainty in the results due to the dramatically different rates of detected apnea in different institutions, which appear to be related to the use of different monitoring devices. Given the limitations of this combined analysis, each physician and institution must decide what is an acceptable risk for postoperative apnea.

Aging↗
PubMed1995

Ethanol, morphine and barbiturate alter the hemodynamic and cerebral response to cocaine in newborn pigs.

Newborns delivered to cocaine-abusing mothers are often exposed to other concurrently consumed illicit drugs, which may alter the hemodynamic and cerebral response to cocaine. This study examined the interaction of ethanol, morphine or barbiturate with cocaine on mean arterial pressure (MAP), cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in newborn pigs. CBF, CMRO2 and cerebral O2 extraction (CEO2) were measured before and 4 and 10 min after cocaine (1.5 mg/kg i.v.) was administered in piglets that were awake, or pretreated with morphine, ethanol or pentobarbital. In awake piglets, cocaine increased CMRO2 and CEO2 while it had no significant effect on CBF. Conversely, in morphine- and ethanol-pretreated piglets, cocaine decreased CMRO2, decreased CBF and had not effect on CEO2. In awake piglets, cocaine increased MAP, whereas in morphine- or ethanol-pretreated piglets, cocaine decreased MAP. In the pentobarbital group, cocaine had no effect. These data demonstrate that other drugs of abuse alter the hemodynamic and cerebral effects of cocaine in the immature animal and may contribute to the central nervous system abnormalities in 'crack babies'.

Animals↗
PubMed1994

The role of opioids in newborn pig fluid percussion brain injury.

The present study was designed to characterize the relationship between cerebral opioid concentration, cerebral hemodynamics, and cerebral oxygenation following percussion brain injury in neonatal pigs. Previous research found that opioids represent a significant vasoactive component in the regulation of the neonatal piglet cerebral circulation. Anesthetized newborn (1-5 days old) pigs equipped with a closed cranial window were connected to a percussion device consisting of a saline-filled cylindrical reservoir with a metal pendulum. Brain injury of moderate severity (1.9-2.3 atm.) was produced by allowing the pendulum to strike a piston on the cylinder. Fluid percussion brain injury decreased pial arteriolar diameter (132 +/- 5 to 110 +/- 5 microns within 10 min). Cerebral blood flow also fell within 10 min of injury and continued to fall progressively for 3 h, resulting in a 46 +/- 4% decrease. Within 30 s of brain injury, there was a transient increase in cerebral hemoglobin-O2 saturation that was reversed to a progressive profound decrease in cerebral hemoglobin-O2 saturation for the next 3 h, as measured by near infrared spectroscopy. CSF opioid concentrations were increased 10 min after brain injury; dynorphin showed the largest proportional increase (5.8 +/- 0.9 fold). The CSF concentration for other opioids continued to increase over 180 min while the dynorphin concentration progressively decreased with time. In naloxone (1 mg/kg i.v.) pretreated piglets, the brain injury induced decrease in arteriolar diameter was attenuated (129 +/- 5 to 121 +/- 5 microns within 10 min). Similarly, the decrease in regional cerebral blood flow and cerebral hemoglobin-O2 saturation observed following brain injury were also blunted by naloxone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗