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Biomedical subjects

J E Brazy

Publications and source records attributed to J E Brazy.

At least 19 recordsLinked to original sources
PubMed1995

Influence of acidosis, hypoxemia, and hypotension on neurodevelopmental outcome in very low birth weight infants.

OBJECTIVE: We previously demonstrated that acidosis (pH < 7.15) predicts poor motor outcome in very low birth weight (VLBW) infants. The present study was undertaken to examine the association between acidosis and developmental outcome in more detail and to better understand the interrelationship of acidosis with related factors such as hypoxemia and hypotension. METHODS: The nursery records of 191 infants enrolled in our VLBW follow-up study were reviewed to identify the type of acidosis (metabolic or respiratory) present, measure the duration of single and cumulative episodes, and examine the interaction of acidosis with hypoxemia and hypotension. The Bayley Scales of Infant Development and a detailed neurologic examination were performed at 6 (n = 158) and 24 (n = 106) months corrected age. RESULTS: At 6 months, both respiratory and metabolic acidosis as well as the total duration and longest single episode of acidosis were significantly correlated with cognitive, motor, and neurologic outcome (P < .0001). By 24 months, only the association of the metabolic component of acidosis with all three outcome measures remained significant. Duration of hypotension independently correlated with outcome at both testing periods (P < .002) but isolated hypoxemia did not. The metabolic component of acidosis and isolated hypotension contributed significantly to the variance in all three outcome measures (P < .05). Duration of hypoxemia, but not hypotension, contributed significantly (53%) to the variance in the metabolic component of acidosis. CONCLUSION: We conclude that it is the metabolic component of acidosis that is important in predicting poor developmental outcome in VLBW infants. The detrimental effect of hypoxemia appears to be closely related to the occurrence of metabolic acidosis while hypotension has an independent effect on outcome.

Acidosis↗
PubMed1991

Cerebral oxygen monitoring with near infrared spectroscopy: clinical application to neonates.

Near infrared spectroscopy is a new noninvasive optical method for bedside monitoring of cerebral oxygenation. It uses differential absorbance of near infrared light to assess relative changes in the oxidation-reduction state of cytochrome aa3, as well as changes in the amounts of oxyhemoglobin, deoxyhemoglobin, and blood volume in the monitored field. Although this technique is applicable to all ages and sizes of patients and to multiple clinical settings, the majority of clinical studies to date have focused on the neonate. These studies have demonstrated its potential for advancing neonatal care and in understanding how diseases and therapies affect cerebral oxygenation. This paper reviews the near infrared spectroscopy technique and summarizes its potential applications in the field of neonatal intensive care.

Blood Gas Monitoring, Transcutaneous↗
PubMed1991

Nursery Neurobiologic Risk Score: important factor in predicting outcome in very low birth weight infants.

We developed a nursery Neurobiologic Risk Score (NBRS) based on potential mechanisms of brain cell injury in preterm infants and correlated it with developmental outcome at the corrected ages of 6, 15, and 24 months. The NBRS was determined at 2 weeks of age and at the time of discharge from intensive care in 58 preterm infants with birth weights less than or equal to 1500 gm. The NBRS correlated significantly with the Bayley Scales of Infant Development, Mental Development Index (MDI) (r = -0.61 to -0.40) and Psychomotor Development Index (PDI) (r = -0.59 to -0.46), and with abnormal neurologic examination findings (r = 0.59 to 0.73) at the three testing periods. Although 12 of the 13 items composing the NBRS individually correlated with one or more outcome variables, seven items (infection, blood pH, seizures, intraventricular hemorrhage, assisted ventilation, periventricular leukomalacia, and hypoglycemia) accounted for almost all of the explained variance. Logistic regression of individual items demonstrated intraventricular hemorrhage to be the most important item for predicting the MDI at 24 months; pH was the most influential item for predicting the PDI at every testing period. A shorter, revised NBRS that included only the seven significant items demonstrated as strong a correlation with developmental outcome as the original NBRS. A revised 2-week score of greater than or equal to 5 or a discharge score of greater than or equal to 6 demonstrated 100% specificity and had a 100% positive predictive value for an abnormal outcome at 24 months of age in this group of infants. We conclude that the NBRS identifies during the intensive care nursery stay those infants at highest risk for an abnormal outcome related to nursery events. In addition, analysis of NBRS items provides insight into the relative importance of individual factors for influencing mental, motor, and neurologic outcome.

Brain Damage, Chronic↗
PubMed1991

Near-infrared spectroscopy.

Near-infrared spectroscopy is a new technique for noninvasive monitoring of tissue oxygenation and hemodynamics. Until now, it has been used solely for research into the physiopathology of the brain. This technique offers considerable untapped potential for research and clinical applications.

Cerebrovascular Circulation↗
PubMed1991

Narcotic sedation stabilizes arterial blood pressure fluctuations in sick premature infants.

Blood pressure (BP) fluctuations in infants with respiratory distress syndrome (RDS) are related to spontaneous respirations and have been associated with an increased incidence of intraventricular hemorrhage. Both initiation of mechanical ventilation in the nonventilated infant and muscle paralysis in the ventilated infant can help stabilize these fluctuations. We hypothesized that narcotic sedation would also be effective in decreasing BP fluctuations when pharmacologic intervention is deemed necessary. Twenty premature infants were paralyzed with pancuronium or sedated with morphine or fentanyl for clinical indications. Blood pressure and respiratory tracings before and after medication were analyzed for average peak systolic BP (SBP) and the percentage of spontaneous respirations (SResp). Fluctuations of SBP were quantitated using the coefficient of variation (CV). A marked reduction was found in both CV and SResp following administration of all three drugs. Peak inspiratory pressure and ventilator rate were increased in the pancuronium group. In 7 out of 14 patients in whom spontaneous respirations persisted following sedation, there was a strong association between the percentage of decrease in CV and SResp. Advantages of narcotic sedation over muscle paralysis are discussed.

Blood Pressure↗
PubMed1990

Cytomegalovirus infection in a neonatal intensive care unit. Subsequent morbidity and mortality of seropositive infants.

In a study of blood transfusion and cytomegalovirus (CMV) infection in 385 infants, 5 (8%) of 60 seropositive infants with birthweights less than or equal to 1250 g acquired CMV. Four infants had become seronegative by the time of viral excretion and demonstrated significant morbidity with one death. Morbidity included variant (atypical) lymphocytosis, thrombocytopenia, Staphylococcal epidermidis and Candida parapsilosis infections, and respiratory deterioration. Interestingly, the infant who exhibited only minimal morbidity was seropositive at the time of viral excretion. CMV seropositivity at birth may not protect low birthweight (LBW) infants from the morbidity and mortality associated with CMV infection.

Antibodies, Viral↗
PubMed1990

Fluctuations of arterial blood pressure decrease with mechanical ventilation in premature infants with respiratory distress syndrome.

Marked fluctuations of arterial blood pressure (ABP) are associated with an increased risk of intraventricular hemorrhage. The pathophysiology is linked to spontaneous breathing. We hypothesized that these fluctuations would decrease after initiation of effective mechanical ventilation. We studied 20 infants treated with nasal continuous positive airway pressure (CPAP) and oxygen for early respiratory distress. Eleven required intubation for clinical indications. Simultaneous ABP and respiratory tracing obtained before and following intubation were analyzed for average peak systolic blood pressure (SBP) and the percentage of spontaneous respirations (SResp). Fluctuations of SBP were quantitated using the coefficient of variation (CV). The remaining 9 infants with minimal lung disease served as a control group. There was a small increase in SBP, and a marked decrease in both CV and SResp following intubation. A significant correlation was found between the percent decreases in CV and SResp. We conclude that beat-to-beat fluctuations of ABP decrease after the initiation of effective mechanical ventilation. This effect is primarily due to a decrease in spontaneous breathing.

Blood Pressure↗
PubMed1988

Cytomegalovirus infection in a neonatal intensive care unit. Blood transfusion practices and incidence of infection.

We studied blood transfusion variables and cytomegalovirus (CMV) infection in 385 infants admitted to the Duke University Medical Center, Durham, NC, neonatal intensive care unit over 14 months. Cytomegalovirus antibody titers were measured at birth and monthly thereafter. Urine cultures for CMV were performed regularly. Infants admitted in the first six months (n = 197) received conventionally prepared blood. Infants admitted in the remaining eight months (n = 188) were given frozen, deglycerolized blood. Of the 105 infants weighing 1250 g or less (low birth weight [LBW]), 90 (86%) received transfusions. Two hundred eighty infants weighed more than 1250 g (non-LBW), and 111 (40%) of these were given blood. In the first six months of the study, three infants had CMV viruria. One case was congenital; two were acquired. Both infants who acquired infection were antibody-positive at birth and received multiple transfusions. In the remaining eight months, five infants had CMV viruria. Two cases were congenital; three were acquired. The three infants who acquired infection were antibody-positive at birth and received multiple transfusions. Our study demonstrates that infants with an LBW are more likely to receive blood transfusion and to be given significantly more blood than non-LBW infants. There was no difference in the number of infants acquiring CMV in the two periods despite the use of different preparations of blood.

Antibodies, Viral↗
PubMed1988

Effects of crying on cerebral blood volume and cytochrome aa3.

To determine if crying alters cerebral hemodynamics and oxidative metabolism in the brain, near infrared spectrophotometry was used to assess relative changes in cerebral blood volume and the oxidation-reduction state of cytochrome aa3. Thirty-six crying episodes were observed, 20 in healthy infants and 16 in infants with respiratory problems. Throughout all crying episodes cerebral blood volume and oxidized cytochrome aa3 demonstrated oscillatory fluctuations every 10 to 20 seconds, with maximum changes during prolonged exhalations. In 86% of episodes baseline blood volume rose and remained elevated during the cry. The relative content of deoxyhemoglobin in cerebral blood also rose, indicating that venous blood is the major contributor to the increase in blood volume. Changes in baseline cytochrome aa3 oxidation varied with the presence of lung disease and with the chronologic age of the infant. Cytochrome reduction with crying occurred significantly more often in infants with respiratory problems than in healthy infants. Cytochrome aa3 became more oxidized in 82% of crying episodes in healthy infants older than 3 days of age, but no change in cytochrome oxidation was usually noted in those younger than 3 days. Thus crying alters cerebral blood volume in all neonates in a pattern consistent with cyclic obstruction to cerebral venous return; it decreases cerebral oxygenation in infants with respiratory problems.

Blood Volume↗
PubMed1986

Autopsy. High yield in neonatal population.

The value of the autopsy in the practice of clinical medicine continues to be debated. While the yield of the autopsy in adults is well documented, similar studies in infants and children are lacking. To understand how frequently the neonatal autopsy provides useful information, we studied all deaths in a level III neonatal Intensive care unit over a three-year period. Clinically active problems at the time of death were tabulated and compared with the final diagnoses obtained from the autopsy report. During the three-year study period, there were 113 deaths with autopsies performed in 71 (63%) of the cases. Significant findings were noted in 39% of patients. These included congenital anomalies (16 patients), Infections (nine patients), unsuspected iatrogenic complications (five patients), and others (11 patients). In 16% of the cases, the autopsy provided the definitive explanation for the cause of death by substantiating an unproved or unsuspected diagnosis. In an additional 18.3% of the cases, the autopsy findings influenced genetic counseling or were important in monitoring patient care. The gross examination was the most useful component of the autopsy, providing 63% of the significant findings. This high rate of return supports a continued high rate of neonatal autopsy.

Autopsy↗
PubMed1986

Changes in cerebral blood volume and cytochrome aa3 during hypertensive peaks in preterm infants.

Relative changes in cerebral blood volume and in the oxidation/reduction state of cytochrome aa3, the terminal member of the electron transport chain in oxidative metabolism, can be simultaneously observed with near infrared spectroscopy. Using this technique, we studied movement-associated blood pressure elevations in three nonparalyzed very low birth weight infants receiving mechanical ventilation. We defined hypertensive peaks as increases in systolic and diastolic blood pressures greater than or equal to 30% over baseline and lasting at least 2 seconds. Ninety percent of monitored time, an increase in tissue blood volume (tBV) immediately followed each blood pressure elevation, with deoxygenated hemoglobin providing the sole or predominant increase in tBV. A simultaneous shift of cytochrome aa3 to a more reduced state usually accompanied the rise in tBV, probably indicating a transient imbalance between oxygen delivery and cellular oxygen utilization and a failure of mechanisms that normally regulate cerebral oxygenation. The consistent association of hypertensive peaks with body movement, coughing, and breath holding, and the predominant increase in deoxygenated hemoglobin suggest that increased intrathoracic pressure transiently impedes cerebral venous return. The repeated fluctuations in intracerebral blood volume and associated shifts to greater cytochrome aa3 reduction with hypertensive peaks provide a possible explanation for the association of fluctuating blood pressure patterns and increased risk for intraventricular hemorrhage.

Blood Volume↗
PubMed1985

Noninvasive monitoring of cerebral oxygenation in preterm infants: preliminary observations.

A noninvasive optical method for bedside monitoring of cerebral oxygenation in small preterm infants was evaluated. Through differential absorbance of near infrared light, changes in the oxidation-reduction level of cytochrome aa3, in the oxygenation state of hemoglobin and in tissue blood volume were assessed in the transilluminated anterior cerebral field. Overall, cerebral oxygenated hemoglobin correlated significantly with transcutaneous oxygen, r = .44 p less than .0001; however, correlation was best in the absence of cardiorespiratory disease. Hypoxia with or without bradycardia led to hemoglobin deoxygenation and a shift in cytochrome aa3 to a more reduced state. When hypoxic episodes came in series or were prolonged, aa3 reduction occurred simultaneous with hemoglobin deoxygenation but its recovery to base-line values sometimes lagged behind the return of hemoglobin oxygenation. In one infant with a large patent ductus arteriosus, even brief episodes of mild bradycardia caused precipitous reduction of cytochrome aa3 before any shift to greater hemoglobin deoxygenation. This response disappeared after ductal ligation. In general, the antecedent state of cerebral oxygenation, the severity and duration of deoxygenation, and the presence or absence of circulatory abnormalities all influenced the aa3 response to hypoxia. Continuous noninvasive near infrared monitoring of cerebral oxygenation can be performed on sick preterm infants at the bedside.

Blood Volume↗