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Biomedical subjects

John M Lorenz

Publications and source records attributed to John M Lorenz.

10 recordsLinked to original sources
PubMed2006

Motor and cognitive outcomes in nondisabled low-birth-weight adolescents: early determinants.

OBJECTIVES: To describe motor and cognitive outcomes in nondisabled low-birth-weight (LBW) adolescents and to determine the relation of specific prenatal, perinatal, and neonatal risk factors to these outcomes. DESIGN: A prospective epidemiological study. SETTING: An adolescent follow-up of a regional LBW (<2000 g) cohort born in or admitted to 3 hospitals between September 1, 1984, and June 30, 1987 (n = 1105). Of 862 eligible survivors, 628 (72.9%) underwent assessment at a mean age of 16 years; of these, 33 had severe disability that precluded psychometric evaluation. The 474 nondisabled adolescents undergoing assessment at home had slightly less social risk at birth than did all other nondisabled eligible adolescents. PARTICIPANTS: The 474 nondisabled LBW adolescents assessed at home. Main Exposures Basic birth characteristics (social risk, sex, fetal growth ratio, and gestational age), neonatal cranial ultrasound abnormalities, and other early medical complications. MAIN OUTCOME MEASURES: Riley Motor Problems Inventory and Wechsler Abbreviated Scales of Intelligence. RESULTS: Nondisabled LBW adolescents had an excess of motor problems compared with the normative sample. The IQ scores, although within the normal range, were significantly lower than population norms. Independent predictors of total motor problems included male sex, white matter injury on neonatal ultrasound, and days of ventilation. Independent predictors of lower Full Scale IQ scores included social disadvantage, fetal growth ratio, and white matter injury on neonatal ultrasound. CONCLUSIONS: Specific prenatal, perinatal, and neonatal risk factors influence motor and cognitive performance in nondisabled LBW survivors well into adolescence, even when controlling for social risk. Advances in maternal-fetal and neonatal care can substantially improve these long-term outcomes.

Adolescent↗
PubMed2005

Alpha-thalassemia major presenting in a term neonate without hydrops.

We describe the clinical and pathologic features of an unusual case of alpha-thalassemia major in a patient who survived to term and lived for 9 days. The neonate was nonhydropic and the clinical picture was dominated by severe hypoxia with pulmonary hypertension. The diagnosis was not suspected until postnatal examination of the blood smear, which prompted the performance of hemoglobin electrophoresis and subsequent molecular confirmation. This case illustrates that alpha-thalassemia major should be in the differential diagnosis of hypoxic neonates even in the absence of hydrops.

Diagnosis, Differential↗
PubMed2005

Ethical dilemmas in the care of the most premature infants: the waters are murkier than ever.

PURPOSE OF REVIEW: Summarize the literature relevant to ethical issues surrounding decisions to provide intensive care to extremely premature newborns. RECENT FINDINGS: A Texas Supreme Court decision and a position paper are noteworthy for health professionals participating in management decisions with families at risk for extremely preterm delivery. SUMMARY: In Miller v HCA, the Millers sued the Hospital Corporation of America for resuscitating their approximately 23-week gestation daughter against their wishes. The baby survived with severe neurodevelopmental disabilities. They were awarded $59.9 million in a jury trial. However, the judgment was reversed by the court of appeals, which ruled that parents have no right to withhold urgently needed life-sustaining medical treatment from children with non-terminal impairments, deformities, or disabilities, regardless of their severity. The Supreme Court of Texas upheld that ruling, but reasoned that parents have no right to refuse resuscitation of extremely premature infants prior to birth because they cannot be fully evaluated until birth; therefore, decisions before birth could not be fully informed. Robertson (Hasting Center Report 2004) supports precluding parental refusal of resuscitation before birth. He argues that parents have a right to withhold or withdraw medical treatment from a non-terminally ill child, but only if the child will lack capacity for symbolic interaction. Such severe limitation of quality of life concerns in decision making for extremely premature newborns is inconsistent with current published guidelines, the positions of noted bioethicists, and the practice of many neonatologists. Further, the additional information attained by initiating intensive care in the most premature infants does not justify doing so without parental consent.

Female↗
PubMed2004

Fluid and electrolyte therapy and chronic lung disease.

PURPOSE OF REVIEW: To evaluate the role of fluid and electrolyte therapy in the pathogenesis of chronic lung disease. RECENT FINDINGS: There have been no new studies since 2000, and there are minimal data addressing this issue specifically in infants at highest risk of chronic lung disease (ie, extremely low birth weight infants). Most observational studies demonstrate a significant association between increased fluid intake or differences in measures of changes in total body water balance in the first week of life and chronic lung disease. However, a metaanalysis of three randomized, controlled clinical trials did not reveal a significant increase in the risk of chronic lung disease with higher fluid intakes. The results of two randomized, controlled trials of different sodium intakes were conflicting regarding whether increased intake led to an increased prevalence of chronic lung disease. SUMMARY: The evidence is insufficient to conclude that fluid and electrolyte therapy plays a role in the pathogenesis of chronic lung disease. Even if fluid and electrolyte therapy does play a small role, the data are insufficient to help with decisions about what fluid and electrolyte intake in an individual infant in a specific clinical setting might reduce the risk of chronic lung disease. However, net negative water and sodium balances and the resultant contraction of the extracellular space are probably physiologic in preterm infants in the first week of life and evidence suggests that a positive water and sodium balance and expansion of the extracellular space during this period increase morbidity. It is not clear what degree of contraction is appropriate or whether varying degrees of contraction of the extracellular space alter morbidity.

Chronic Disease↗
PubMed2003

Prospective risk of fetal death in singleton, twin, and triplet gestations: implications for practice.

OBJECTIVE: To evaluate the prospective risk of fetal death in singleton, twin, and triplet pregnancies and to compare this risk with fetal and neonatal death rates. METHODS: We analyzed 11,061,599 singleton, 297,622 twin, and 15,375 triplet gestations drawn from the 1995-1998 National Center for Health Statistics linked birth and death files. Prospective risk of fetal death was expressed as a proportion of all fetuses still at risk at a given gestational age and compared with fetal death rate. Fetal death risk and neonatal death rates were represented graphically for singletons, twins, and triplets. RESULTS: The prospective risk of fetal death at 24 weeks was 0.28 per 1000, 0.92 per 1000, and 1.30 per 1000 for singletons, twins, and triplets, respectively. At 40 weeks, the corresponding risk was 0.57 per 1000 and 3.09 per 1000 for singletons and twins, respectively and, at 38 or more weeks, 13.18 per 1000 for triplets. Plots of gestation-specific prospective risk of fetal death and neonatal mortality converged for singletons and twins at term but crossed for triplets at approximately 36 weeks' gestation. CONCLUSION: Prospective risk of fetal death is greater for triplets and twins than for singletons and greater for triplets than for twins during the third trimester. The pattern corroborates with uteroplacental insufficiency as a suspected underlying mechanism. When prospective risk of fetal death exceeds neonatal mortality risk, delivery might be indicated. When this model is used, this data set suggests that it might be reasonable to consider delivery of twins by 39 weeks and triplets by 36 weeks to improve perinatal outcome.

Adult↗
PubMed2003

When are observational studies adequate to assess the efficacy of therapeutic interventions?

Four conditions are proposed under which observational research may be adequate to access the efficacy of therapeutic interventions. First, a randomized controlled trail is unethical, not feasible, or not cost-effective. Second, the study design is rigorous, optimal to test the a priori hypothesis, and faithfully executed. The cohort study is the analytical observational design least susceptible to biases and confounding. Even this design, however, may be impractical when the outcome is relatively rare or the interval between the exposure and outcome is relatively long. In these circumstances, the case-control study yields more timely information with less resource expenditure. Third, additional evidence supports the interpretation that the association between the therapeutic intervention and the health outcome is very likely to be causal (ie, the exposure is documented to precede the outcome; the effect size is large; a dose-responses relationship can be demonstrated; the outcome is associated only with the exposure and the exposure produces only the outcome of interest; the relationship is consistently identified in different populations with different experimental designs; or an etiologic mechanism for the association can be proposed). Fourth, certain features of the treatment-health outcome relationship are favorable to drawing inferences from observational research. These features include a large effect size; treatment assignment that is not a function of clinician or patient choice (as in ecologic designs); an outcome that follows the exposure closely in time; and the circumstance in which few other variables affect the risk of the outcome and these variables are well known and easily controllable in the study design or analysis. A useful exercise for large-scale changes in treatment is to examine population-wide health trends for their consistency or inconsistency with the proposition that the new intervention is effective.

Cohort Studies↗
PubMed2003

Management decisions in extremely premature infants.

Survival rates in excess of 25% at 23 weeks' gestation and in excess of 50% at 24 weeks' gestation have been reported among live births in the 1990s within tertiary perinatal care centres in the USA and Australia. Decisions about medical management at these gestational ages can no longer be based merely on whether survival is possible. Relevant moral considerations include the primacy of the newborn's best interests, parental autonomy, physicians' duties of beneficence and non-maleficence, and distributive justice. There is significant variability between developed nations in the survival of extremely premature infants among cohorts born within perinatal tertiary care centres. This is, at least to some degree, the result of differences in the aggressiveness of obstetrical and neonatal management at these gestational ages. There is also great variability in the prevalence of major neurodevelopmental disability among survivors. Moreover, the prevalence of major disabilities does not inform quality-of-life considerations adequately. Despite similar gestational age ranges over which the benefit:burden ratio of aggressive obstetric and neonatal care is questioned in developed countries, there is marked variation in the frequency with which it is provided within these ranges. This is understandable given the relevant moral values and the different ways in which competing values will be balanced by different individuals, cultures and societies; the increasing survival of extremely premature infants, but the persistence of high (but widely variable) prevalences of major disabilities reported among survivors and even higher prevalences of mild-to-moderate neurodevelopmental sequelae; our imperfect ability to estimate an individual extremely premature infant's prognosis; and the complexities of estimating the quality of life from the individual's own perspective.

Australia↗
PubMed2003

Labor and delivery factors in brain damage, disabling cerebral palsy, and neonatal death in low-birth-weight infants.

OBJECTIVE: We assessed the relationships between active labor and neonatal death, neonatal brain damage, and disabling cerebral palsy in low-birth-weight infants. STUDY DESIGN: A population-based cohort of 961 infants with birth weights of 580 to 2000 g and gestational ages >or=26 completed weeks. Neonatal brain damage was assessed by ultrasound scanning in the first weeks of life; disabling cerebral palsy was assessed at 2 years of age (corrected for gestational age). RESULTS: After being controlled for possible confounders, active labor was associated significantly with an increased risk of parenchymal echodensities/lucencies and/or ventricular enlargement (odds ratio, 2.3; 95% CI, 1.2-4.5) but not with germinal matrix/intraventricular hemorrhage (odds ratio, 1.3; 95% CI, 0.8-2.1), neonatal death (odds ratio, 1.8; 95% CI, 0.8-4.0), or disabling cerebral palsy (odds ratio, 1.6; 95% CI, 0.7-3.7). In vertex presentations only, active labor was associated with a nearly 4-fold increase in risk of neonatal death (odds ratio, 3.8; 95% CI, 1.3-10.9). In nonvertex presentations only, active labor was associated strongly with parenchymal echodensities/lucencies and/or ventricular enlargement (odds ratio, 4.3; 95% CI, 1.2-15.6) and disabling cerebral palsy (odds ratio, 8.2; 95% CI, 1.4-49.9). CONCLUSION: The only adverse outcome that was associated consistently with active labor was parenchymal echodensities/lucencies and/or ventricular enlargement. Fetal presentation modified the relationships between active labor and adverse outcomes. Delivery mode (whether vaginal or cesarean delivery) was not associated with any of the outcomes that were evaluated.

Brain Damage, Chronic↗