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Biomedical subjects

G E Knox

Publications and source records attributed to G E Knox.

At least 19 recordsLinked to original sources

Antenatal magnesium exposure and neonatal demise.

OBJECTIVE: To assess the effect of antenatal magnesium sulfate exposure on neonatal demise. STUDY DESIGN: A retrospective analysis of prospectively captured data from 100 tertiary centers between May 1997 and January 2000 was performed. Included were nonanomalous newborns who were admitted to the neonatal intensive care unit between 23 and 34 completed weeks' gestation. Predictors of neonatal demise were determined from a pool of 24 candidate variables in a univariate analysis. A multivariate predictive model for mortality was constructed by using the variables that had significant interactions with the rate of demise (P < or = .1). RESULTS: A total of 12,876 cases were available for analysis. When these cases were stratified according to gestational age, magnesium was associated with a significant reduction in neonatal demise (OR, 0.67; 95% CI, 0.54 to 0.84; P =.0005). The effect remained when controlling for both gestational age and indication for therapy (adjusted OR, 0.70; 95% CI, 0.56 to 0.89; P =.003). The effect was similar in direction and magnitude in the final model after controlling for additional antenatal factors (OR, 0.82; 95% CI, 0.65 to 1.04; P =.108). CONCLUSION: Antenatal magnesium exposure is not associated with neonatal death, regardless of indication for therapy.

Adult↗

Risk management and electronic fetal monitoring: decreasing risk of adverse outcomes and liability exposure.

Electronic fetal monitoring (EFM) has the potential to promote fetal health and improve neonatal status at birth; however, EFM as a stand-alone tool is ineffective in avoiding preventable adverse outcomes. It is effective only when used in accordance with published standards and guidelines by professionals skilled in correct interpretation and when appropriate timely intervention is based on that interpretation. Interpretation and intervention are best accomplished as a collaborative perinatal team rather than individual activity. Only in these circumstances can EFM optimally contribute to fetal well-being and subsequent neonatal health. Risk management strategies to decrease potential liability are presented that can be accomplished with careful planning and collaboration among perinatal team members.

Female↗

Dispelling urban myths in healthcare risk management.

Applied research to explore and challenge myths in healthcare risk management is pivotal to the growth of the profession. The authors demonstrate this process through exploring patient safety and malpractice issues on weekdays compared with on weekends and holidays. Analysis suggests that claim volume is driven by service volume.

Delivery, Obstetric↗

High reliability perinatal units: an approach to the prevention of patient injury and medical malpractice claims.

Perinatal units differ in their ability to prevent patient injury and medical malpractice litigation. Obstetrical units with favorable performance are distinguished by common organizational and clinical features. Organizationally, they resemble what behavioral scientists define as "high-reliability organizations" (i.e., the ability to operate technologically complex systems essentially without error over long periods). Clinically, practices are based on nationally recognized guidelines and/or an operational philosophy of "safety first." These organizational and clinical features are described so that physicians, nurses, and administrators might view their own clinical environments in the context of this perspective.

Female↗

Downsizing, reengineering and patient safety: numbers, newness and resultant risk.

Downsizing and reengineering are facts of life in contemporary healthcare organizations. In most instances, these organizational changes are undertaken in an attempt to increase productivity or cut operational costs with results measured in these terms. Less often considered are potential detrimental effects on patient safety or strategies, which might be used to minimize these risks.

Hospital Restructuring↗

Is it time to reassess the risk for the growth-retarded fetus with normal Doppler velocimetry of the umbilical artery?

OBJECTIVE: Previous studies demonstrate an association between abnormal umbilical artery Doppler velocimetry and the birth of a small-for-gestational-age infant and between abnormal result and adverse neonatal outcome. The hypothesis is that preterm growth-retarded infants with normal antenatal velocimetry have outcomes similar to other preterm infants, whereas preterm small-for-gestational-age infants with abnormal Doppler results define a subgroup with increased morbidity. STUDY DESIGN: For 100 live-born infants, at risk for fetal growth retardation and undergoing antenatal Doppler and targeted ultrasonographic examinations, we assessed a number of complete neonatal outcome parameters. RESULTS: Ten neonatal deaths occurred in the study population, seven with abnormal Doppler results and three with normal Doppler results. Of the 90 surviving infants, gestational age at delivery was not different between the Doppler normal and abnormal neonates, whereas birth weight (1714 gm vs 1379 gm) was higher in the Doppler normal group (p = 0.006). The presence of intraventricular hemorrhage (20% vs 6%) was higher in the abnormal group (p = 0.05). Abnormal Doppler results defined an infant group destined for prolonged hospitalization, mean intensive care days (21 vs 9), and special care nursery days (25 vs 9). Thirty-eight percent of small-for-gestational-age babies had a normal Doppler result. Analysis of variance indicated small-for-gestational-age infants with abnormal Doppler results (n = 20) had a mean intensive care unit stay of 31 days, significantly different (p = 0.005) from small-for-gestational-age infants with normal Doppler results (n = 14), non-small-for-gestational-age infants with abnormal results (n = 21), and non-small-for-gestational-age infants with normal results (n = 35) whose mean intensive care unit stays were 14, 12, and 7 days, respectively. Gestational age at delivery (33.0 weeks) was not different among these groupings, not accounting for the observed differences. CONCLUSION: Normal antenatal velocimetry defines a distinct subgroup of preterm small-for-gestational-age infants at less risk for prolonged hospitalization compared with those with abnormal velocimetry.

Blood Flow Velocity↗

Evaluation of fetal cardiac arrhythmias. Ultrasound findings and neonatal outcome.

During a four-year period, 3,882 fetal diagnostic ultrasounds were performed and 162 patients (4% of all patients scanned) were referred to our perinatal center for evaluation of fetal cardiac arrhythmia. Fetal echocardiography subsequently revealed an arrhythmia in 80 (49%) of these patients. The rhythm disturbances noted were premature atrial or ventricular contractions (n = 65, 81%), tachyarrhythmia (n = 8, 10%), and bradyarrhythmia (n = 7, 9%). Three of the bradycardic fetuses evaluated had complete heart block associated with anatomic abnormalities. In seven tachycardic fetuses, the finding of fetal compromise was followed by intervention. The majority of fetuses with cardiac rhythm disturbance will have premature atrial or ventricular contractions and will have normal echocardiographic evaluation and neonatal outcome. Sustained tachyarrhythmias and bradyarrhythmias are more likely to be associated with fetal morbidity. Based upon the findings of this study and others, we propose a scheme for follow-up of the fetus referred with an irregular cardiac rhythm.

Bradycardia↗

Is pulsed Doppler velocimetry useful in the management of multiple-gestation pregnancies?

Few studies have addressed the significance of umbilical artery pulsed Doppler velocimetry in multiple gestation. Level II ultrasonography and pulsed Doppler studies were performed in 94 twin pairs and seven sets of triplets, which yielded data on 207 fetuses. A systolic/diastolic ratio was calculated for each fetus; abnormal pulsed Doppler velocimetry showed high correlation with adverse pregnancy events. Those with abnormal Doppler findings tended to be born 3 to 4 weeks earlier and to exhibit a greater number of stillbirths and structural malformations, as well as greater morbidity, when compared with fetuses without abnormal Doppler results. Fifteen of 17 infants with abnormal antenatal waveforms suffered serious morbidity. Seven were small for gestational age, and two were borderline for small for gestational age. An additional five infants with abnormal waveforms were appropriate for gestational age but were either recipient or donor in the twin transfusion syndrome. Eleven fetuses with this syndrome are described. Donor twins tended to be severely small for gestational age, with 7 of the 11 infants showing elevated systolic/diastolic ratios. Amniotic fluid volume tended to be diminished in the donor's sac but normal or increased in the recipient's sac. The observations in the study correlate with suspected physiologic changes of this syndrome. Because present findings suggest that fetuses with abnormal velocimetry suffer increased morbidity and mortality, a more rational method of management that uses Doppler data is suggested for multiple gestations.

Blood Circulation↗

Risk factors for preterm premature rupture of fetal membranes: a multicenter case-control study.

To assess the association between women with preterm premature rupture of membranes and 41 potential risk factors, we conducted a case-control study in six United States tertiary perinatal centers. The study involved completion of a comprehensive questionnaire for 341 women with preterm premature rupture of membranes in singleton pregnancies from 20 to 36 weeks' gestation and 253 control women matched for maternal age, gestational age, parity, clinic or private patient status, and previous vaginal or cesarean delivery. Univariate analysis revealed 11 variables associated with a significantly (p less than 0.05) increased risk of preterm premature rupture of membranes. After multiple logistic regression analysis, three variables remained in the model as independent risk factors: antepartum vaginal bleeding in more than one trimester (odds ratio 7.4; 95% confidence interval, 2.2, 25.6), current cigarette smoking (odds ratio, 2.1; 95% confidence interval, 1.4, 3.1), and previous preterm delivery (odds ratio, 2.5; 95% confidence interval, 1.4, 2.5). Cessation of cigarette smoking by pregnant women may reduce the risk of preterm premature rupture of membranes. Further study is necessary to determine the nature of the relationship between antepartum vaginal bleeding and preterm premature rupture of membranes.

Case-Control Studies↗

Pulsed Doppler umbilical artery waveforms: significance of elevated umbilical artery systolic/diastolic ratios in the normally grown fetus.

Previous studies have demonstrated a high correlation between elevated resistance in the placental circulation, evidenced by abnormal umbilical artery systolic-to-diastolic (S/D) ratios, and the subsequent birth of a small for gestational age (SGA) infant. However, few data exist on the significance of elevated S/D ratios for pregnancies in which outcome does not involve an SGA infant. Pulsed Doppler spectral recordings and level II ultrasound examinations were performed 373 times in 256 referred high-risk patients. Doppler data were not used for patient management decisions. Thirty-two women with elevated umbilical artery S/D ratios of 4.5 or greater (defined as abnormal regardless of gestational age) gave birth to non-SGA infants. The ultrasound characteristics and outcome for this group were compared with those of 200 patients who were also non-SGA but who exhibited normal waveforms and with 24 SGA infants with predominantly abnormal waveforms. Thirty-one percent of the non-SGA infants with abnormal waveforms had structural malformations, a rate significantly higher (P less than or equal to .03) than the 18% malformation rate in the normal-waveform group. Further, the stillbirth rate and number of terminations of pregnancy for lethal anomalies were five times greater in the non-SGA group with abnormal waveforms than in the non-SGA group with normal waveforms (P less than or equal to .001). A wide variety of structural malformations was observed in the abnormal-waveform group, most frequently involving the central nervous system. Amniotic fluid volume tended to be decreased in the SGA group, whereas increased amniotic fluid volume or hydramnios was seen in 23% of the non-SGA abnormal-waveform group.

Amniotic Fluid↗

Changing outcome of extremely premature infants (less than or equal to 26 weeks' gestation and less than or equal to 750 gm): survival and follow-up at a tertiary center.

Management of extremely premature infants is controversial because limits of viability are not established. From 1981 to 1987, 175 infants were admitted to the neonatal intensive care unit at Minneapolis Children's Medical Center with gestational ages less than or equal to 26 weeks and birth weights less than or equal to 750 gm. To assess current prognosis and to analyze trends over time, survival data and developmental characteristics of surviving infants were reviewed. During the study period, antenatal obstetric management was assertive, with liberal indications for tocolysis and expectant management for preterm prolonged membrane rupture, with the goal of delivery of infants in a nonasphyxiated condition. Ninety-one percent of infants were inborn and were managed aggressively after birth with full neonatal support. Survival increased from 21% in 1981-1982 to greater than 50% in 1986-1987 and occurred as early as 23 weeks' gestation. Seventy-one percent of all deaths occurred within 48 hours of birth, and late death (greater than 28 days) was uncommon. At follow-up, 23% of survivors were impaired, a proportion that remained relatively constant during the study period. Improvements in survival were not associated with an increased proportion of impaired infants. Survival with good outcome is attainable at gestational ages and birth weights previously considered nonviable. For obstetricians, neonatologists, and parents, knowledge of such current data can play an important role in making appropriate management decisions for both mother and infant.

Female↗

The predictability of the small-for-gestational-age infant by real-time ultrasound-derived measurements combined with pulsed Doppler umbilical artery velocimetry.

During a 15-month period 373 level II ultrasound examinations were performed in 256 high-risk patients. In addition, pulsed Doppler spectral recordings of blood flow in the fetal umbilical arteries were made. A systolic/diastolic ratio was then calculated for each fetus. Real-time ultrasound-derived estimated fetal weight with the use of biparietal diameter and abdominal circumference was also calculated. The estimated fetal weights were categorized by placing them in a percentile for gestational age according to published nomograms. Complete birth data and outcomes were obtained in all patients. Both the systolic/diastolic ratio and ultrasound-estimated fetal weight grouped by percentile ranking for gestational age were highly predictive (p = 0.001) of babies who were subsequently born small for gestational age. Seventy-nine percent of the infants small for gestational age had umbilical artery systolic/diastolic ratios greater than or equal to 4, whereas only 21% had normal systolic/diastolic ratios. Forty-three percent of the infants who were small for gestational age had ultrasound-estimated fetal weights less than or equal to 10th percentile for the gestational age at which it was measured. Umbilical artery systolic/diastolic ratios, which reflect an increase in peripheral resistance in the placental circulation, showed a highly predictive and discriminatory index for the evaluation of the fetus suspected of having growth retardation.

Birth Weight↗

Candida chorioamnionitis diagnosed by amniocentesis with subsequent fetal infection.

Isolation of Candida albicans from the vaginal secretions of pregnant women occurs with an incidence of 5-23%. Intrauterine infection caused by Candida during pregnancy is relatively rare; only 81 cases, all diagnosed after delivery, have been reported. We report six cases of candidal chorioamnionitis diagnosed by amniocentesis and confirmed by histologic studies, associated with preterm labor and delivery of five viable infants. Three of the six maternal patients had intrauterine contraceptive devices in situ. Three infants had a diagnosis of congenital cutaneous candidiasis and two had congenital systemic candidiasis, one with monilial pneumonia, and one with meningitis and septicemia. All viable neonates were treated successfully. The sixth, a very immature infant, died soon after delivery. Torulopsis (Candida) glabrata was isolated from this amniotic fluid. C. Albicans is a pathogen that potentially may cause chorioamnionitis and has been associated with high mortality (94%) in infants weighing less than 1500 gm. Use of amniocentesis in patients with preterm labor may allow early detection of subclinical candidal chorioamnionitis, thus guiding appropriate perinatal management.

Adolescent↗

Listeriosis.

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Adolescent↗

Evaluation of gas-liquid chromatography for the rapid diagnosis of amniotic fluid infection: a preliminary report.

Gas-liquid chromatography has been proposed as a possible tool in the rapid diagnosis of amniotic fluid infections. The analysis is based on the identification of specific organic acids derived from bacterial metabolism when organisms are present within the amniotic fluid. We retrospectively subjected 69 samples of amniotic fluid which had been obtained by transabdominal amniocentesis to analysis by gas-liquid chromatography. Forty-seven samples were derived from patients who either were in premature labor or had premature rupture of membranes with associated premature labor. Twenty-two specimens which served as a comparison group were obtained from patients who underwent amniocentesis for assessment of fetal maturity. The results obtained from chromatographic analysis are presented, and the possible applications of this technique to the clinical situation are discussed.

Adult↗