Biomedical subjects

J W Van Hook

Publications and source records attributed to J W Van Hook.

17 recordsLinked to original sources

PubMed2000

Blood cell lead, calcium, and magnesium levels associated with pregnancy-induced hypertension and preeclampsia.

This study compares the red blood cell (Rbc) levels of lead (Pb), calcium (Ca), and magnesium (Mg) in relation to blood pressure in 39 pregnant women in the third trimester of pregnancy. The study population included 20 women with normal pregnancies, 15 with mild hypertension, and 4 with severe hypertension and preeclampsia. The mean +/- SD for each group was calculated and the difference between the means of the normotensive and the other groups were compared by analysis of variance. Significant differences from normal to the preeclamptic pregnancies were in (1) elevated Rbc Pb (p < or = 0.001), (2) lower Rbc Ca (p < or = 0.001), and (3) lower Rbc Mg/Pb ratio (p < or = 0.0001). Pearson's rank correlation between blood pressure showed a direct relation to the Rbc Pb level (p < or = 0.01) and an inverse relation to the Rbc Ca and Mg/Pb ratio (p < or = 0.004, < or = 0.007). Apparently, prenatal blood pressure is directly proportional to Rbc Pb content and related or modified by Rbc Ca and Mg.

Adolescent↗

PubMed1999

Presentation of venous thromboembolism during pregnancy.

OBJECTIVE: We sought to characterize the presentation, recurrence, and outcome of venous thromboembolism during pregnancy. STUDY DESIGN: We performed a 12-year, single-center, retrospective review of 38 patients with venous thromboembolism during pregnancy. The independent variables were subjected to univariate analysis (unpaired t test for normally distributed continuous variables and Fisher exact test for discrete variables). P <.05 was considered significant. RESULTS: There was no significant difference for the following variables according to time of presentation (antepartum vs post partum): gestational age at delivery (37.4 +/- 6.6 wk vs 38.1 +/- 2.4 wk; P =.7), birth weight (3257 +/- 458 g vs 3093 +/- 719 g; P =.3), and mode of delivery (2 vs 4 cesarean deliveries; P =.15). There were 2 maternal deaths. All 3 women with antepartum recurrent venous thromboembolism (despite heparin prophylaxis) had findings of protein C deficiency, protein S deficiency, and lupus anticoagulant-anticardiolipin antibody, respectively. CONCLUSION: The gestational age at presentation appears more equally distributed throughout gestation than previously reported. Notwithstanding limited numbers, the recurrence of venous thromboembolism despite use of prophylactic heparin therapy suggests the need to reexamine the current recommendations for heparin dosing.

Adult↗

PubMed1999

Maternal oxygen transport variables during the third trimester of normal pregnancy.

OBJECTIVE: The aim of this study was to measure and calculate oxygen transport variables in uncomplicated term pregnancies. STUDY DESIGN: Ten normotensive primiparous women between 36 and 38 weeks' gestation underwent pulmonary and radial arterial catheterization as part of a larger study. Seven women had studies repeated at approximately 12 weeks post partum. Measurements were made with patients in the left lateral recumbent position after a 30-minute stabilization period. Cardiac output was measured with the thermodilution technique. Blood samples were obtained simultaneously from the pulmonary and radial arteries and analyzed in duplicate for oxygen content with a blood gas analyzer. RESULTS: The oxygen contents of both arterial and mixed venous blood are significantly lower (P <.05) in the third trimester of pregnancy (15.96 and 11.97 mL/dL, respectively) than in the postpartum period (18.00 and 13.54 mL/dL). The fall in oxygen content during pregnancy prevents any significant increase in oxygen delivery in the third trimester (867. 59 mL/min) relative to the postpartum period (806.50 mL/min, P not significant). CONCLUSION: This is the first report of directly measured oxygen transport variables in healthy pregnant women.

Biological Transport↗

PubMed1999

Management of complicated preeclampsia.

The complicated preeclamptic patient represents a challenge for the clinician faced with her antepartum or postpartum care. The most serious sequelae of preeclampsia account for a significant portion of maternal morbidity and mortality. Severe preeclampsia also results in an appreciable portion of perinatal morbidity and mortality. In this review, developing trends in the treatment of severe preeclampsia are discussed. Expectant treatment of the patient remote from term, anesthesia choices, and delivery route are reviewed. Developing trends in the pharmacological approach to complicated preeclampsia are discussed. New concepts in the treatment of cerebrovascular preeclampsia and hepatic rupture are outlined and reviewed.

Catheterization↗

PubMed1999

Amniotic fluid B12, calcium, and lead levels associated with neural tube defects.

The group mean differences and relationships between folate, B12, calcium, lead, and methionine levels in amniotic fluid from 29 non-NTD and 11 NTD pregnancies (15-20 weeks' gestation age) were determined. The study population was predominantly Hispanic in both groups (48% in non-NTD and 36% in NTD group) with an average maternal age of 29 years in the non-NTD group and 24 years in the NTD group; and, an average gestation age of 18.5 weeks in the non-NTD and 17.5 weeks in the NTD group. The folate, B12, lead, calcium, and methionine levels of the two groups were compared by Student's t-test and by Pearson's correlation. The NTD levels were lower for calcium (p< or =0.0001), B12 (p< or =0.001), and methionine (P< or =0.001); but, the lead level was higher (p< or =0.0001). A negative correlation was observed between lead and both B12 (p< or =0.007) and methionine (p< or =0.02).

Adult↗

PubMed1999

Amniotic fluid amino and nucleic acid in normal and neural tube defect pregnancies. A comparison.

OBJECTIVE: To explore the relationship between fetal amino acids (AAs), which are the components of structural proteins and nucleic acids, and the changes associated with neural tube defects (NTD). STUDY DESIGN: Ten weekly amniotic fluid (AF) samples from normal pregnancies (non-NTD) and 10 from NTD pregnancies between 16 and 20 weeks' gestational age were analyzed for AAs, and the weekly average for the non-NTD and NTD groups was determined. The group mean levels were compared by ANOVA. RESULTS: The weekly group mean levels of methionine, serine and aspartic acid were significantly lower than the weekly group mean levels of the other AAs. The group mean levels of methionine were significantly lower for NTD than for non-NTD pregnancies. CONCLUSION: The mean methionine level in NTD pregnancies was the only AA alteration in NTD. Although the AF levels of the non-NTD pregnancies showed that the levels of serine, aspartic acid and methionine were 3- to 19-fold lower than those of the other AAs, only methionine is essential. Consequently, methionine is rate limiting with respect to the role of structural proteins and nucleic acids in the fetus.

Amino Acids↗

PubMed1998

Amniotic fluid B12 and folate levels associated with neural tube defects.

Amniotic fluid levels of B12 and folate in neural tube defect (NTD) affected pregnancies were compared with the weekly group mean +/-SD changes in amniotic fluid B12 and folate levels of 10 unaffected pregnancies each week between 15 and 20 weeks' gestation age. Comparison was by analysis of variance (ANOVA) and Pearson's correlation to B12 and folate levels and to the NTD samples of corresponding gestation age. Amniotic fluid B12 and folate decreased 67 and 62%, respectively, between 15 and 20 weeks' gestation in the unaffected pregnancies, associated with an increase in amniotic fluid volume. The mean +/-SD B12 and folate of the NTD affected pregnancies (308+/-156 pg/mL and 3.1+/-1.6 ng/mL) were below the mean +/-SD B12 and folate of the total population of unaffected pregnancies (453+/-155 pg/mL and 3.9+/-1.2 ng/mL). The correlation between gestation age and amniotic fluid B12 was -0.9914 (p< or =.0001) and -0.9599 (p< or =.002) for amniotic fluid folate. The B12 levels of the affected pregnancies were below the range of unaffected pregnancies in four of the nine affected pregnancies, and folate levels in two of the nine affected pregnancies.

Amniotic Fluid↗

PubMed1998

Aeromedical transfer of preterm labor patients.

Obstetric patients are transported by air quite frequently. We evaluated transport times, obstetric outcomes, air-versus-ground transport costs, and related data on 22 helicopter aeromedical transports of pregnant patients with preterm labor. We found no significant differences between patients who delivered and those who did not when comparing transport time (167.1 +/- 41.9 minutes versus 177.1 +/- 56.2 minutes), air distance of transport (122.9 +/- 44.8 miles versus 143.6 +/- 23.8 miles), and other outcome measures. No deliveries occurred in flight. Air transport costs were significantly greater than estimated ground transfer ($4613.64 +/- $581.12 versus $604.02 +/- $306.38; P < .01). Two-way air transfer of preterm labor patients over moderate distances is more costly than contracted ground transfer costs at our institution.

Air Ambulances↗

PubMed1997

Acute respiratory distress syndrome in pregnancy.

Acute respiratory distress syndrome is a serious sequelae of many serious illnesses during pregnancy. An understanding of acute respiratory distress syndrome is central to the proper care of a patient with the disorder. Acute respiratory distress syndrome results in diminished pulmonary compliance and respiratory shunt mediated hypoxemia. Furthermore, the initial pulmonary injury in acute respiratory distress syndrome may be further worsened by therapeutic hyperoxia and barotrauma. Limitation of peak-plateau airway pressure to less than 35 to 40 cm H2O may reduce barotrauma. Inflammatory mediator therapy may hold future promise in attenuation of lung injury induced by acute respiratory distress syndrome. Aggressive care may help those pregnant patients afflicted with acute respiratory distress syndrome.

Female↗

PubMed1997

Prolonged fetal bradycardia secondary to maternal hypothermia in response to urosepsis.

Fetal bradycardia is a well-known response to maternal hypothermia, as induced at open-heart surgery, but heretofore has not been reported in conjunction with hypothermia from urosepsis. A 24-year-old Vietnamese woman admitted at 33 weeks estimated gestational age with pyelonephritis secondary to Escherichia coli developed several episodes of maternal hypothermia to 35-36 degrees C. During each episode of maternal hypothermia, the baseline fetal heart rate fell to 90-100 bpm, but with retained reactivity. During each episode, maternal vital signs were otherwise stable and oxygen saturation was normal as measured by pulse oximetry. Interpretation of fetal bradycardia during episodes of maternal urosepsis is complex. If seen in conjunction with maternal hypothermia, and in the presence of normal maternal cardiac and respiratory function, bradycardia is unlikely to represent fetal distress.

Adult↗

PubMed1996

Third-trimester arterial blood gas and acid base values in normal pregnancy at moderate altitude.

OBJECTIVE: To report arterial blood gas and acid base values of normal nulliparous patients at moderate altitude for commonly used maternal positions. METHODS: Ten normotensive nulliparous women between 36 and 38 weeks' gestation volunteered to undergo radial and pulmonary artery cannulation as part of a larger study. Following instrumentation, baseline assessments were made in the left lateral recumbent position after a 30-minute stabilization period. Sequential measurements were then obtained in the left lateral, right lateral, supine, knee-chest, sitting, and standing positions. Blood samples were analyzed in duplicate for oxygen content on a blood gas analyzer. Statistical analysis was performed by analysis of variance of repeated measures with significance defined at P < or = .05. RESULTS: There was no significant difference in arterial blood gas or acid base values between any positions in this antepartum population of term healthy women. The composite mean values were as follows: pH 7.46, arterial carbon dioxide pressure (PaCO2) 26.6 mmHg, arterial oxygen pressure 88.3 mmHg, bicarbonate 18.2 mEq/L, saturated arterial hemoglobin level 0.96. CONCLUSION: Arterial blood gas and acid base values are not altered by maternal position in the late third trimester of pregnancy. The PaO2 in these women studied at moderate altitude was lower than previously reported for healthy pregnant women studied at sea level. Appropriate interpretation of arterial blood specimens of pregnant women should take into account both the pregnancy and altitude at which the women reside.

Acid-Base Equilibrium↗

PubMed1996

The effects of maternal position and cardiac output on intrapulmonary shunt in normal third-trimester pregnancy.

OBJECTIVE: To assess the effect of pregnancy, maternal position, and cardiac output on intrapulmonary shunting (Qs/Qt) in normotensive nulliparous women near term. METHODS: Ten normotensive nulliparas between 36 and 38 weeks' gestation underwent pulmonary artery catheterization (via the subclavian route) and radial artery canalization. Baseline assessments were made with subjects in the left lateral recumbent position after a 30-minute stabilization period. Measurements were obtained sequentially in the left lateral, right lateral, supine, knee-chest, sitting, and standing positions. Each position change was followed by a 10-minute pre-measurement stabilization period. Cardiac output was measured via the thermodilution technique. Blood samples were obtained simultaneously from the pulmonary and radial arteries and analyzed in duplicate for oxygen content with a blood gas analyzer. Qs/Qt was calculated using the classic shunt equation. Statistical analysis was performed by analysis of variance of repeated measures of Qs/Qt and maternal position. The relationship of Qs/Qt to maternal cardiac output was evaluated by the correlation coefficient. Significance was defined as P < .05. RESULTS: Directly measured Qs/Qt averaged 15.3% in left lateral, 15.2% in right lateral, 13.9% in supine, 12.8% in knee-chest, 13.8% in sitting, and 13.0% in standing positions. There was no statistically significant correlation between Qs/Qt and cardiac output (R2 = 0.11, not significant). CONCLUSION: This is the first report of directly measured Qs/Qt in normal pregnant women in the third trimester. Qs/Qt values reported in pregnancy are higher than those reported in nonpregnant individuals.

Adult↗

PubMed1996

Effect of pregnancy on maternal oxygen saturation values: use of reflectance pulse oximetry during pregnancy.

Our objective was to evaluate the usefulness of pulse oximetry monitoring in a large population of pregnant patients. We designed our study to measure pulse oximetry saturation in a cross section of 952 obstetric inpatients and outpatients. A group of 366 patients identified as normal were compared with abnormal subgroups. A subgroup of 64 patients with saturation measurements less than 96% were further evaluated. Our results indicated that oxygen saturation values did not change appreciably during the course of pregnancy in normal patients. Hypoxemia (saturation measurement less than 96%) was associated with smoking, and hypoxemia with preterm labor occurred more frequently in patients who smoked. Obesity and magnesium sulfate use appeared to be synergistic in the presence of hypoxemia. We concluded that the routine use of pulse oximetry during pregnancy may not be justified. Smoking, obesity, and magnesium sulfate use have some effect on oximetry in pregnant patients.

Adult↗

PubMed1995

Diamond-Blackfan anemia as an unusual cause of nonimmune hydrops fetalis: a case report.

BACKGROUND: Diamond-Blackfan anemia is an unusual cause of childhood anemia that results from an absence of bone marrow red cell precursors. To our knowledge, the in utero development of Diamond-Blackfan anemia has been recognized and reported in only two prior instances. CASE: We report the case of a patient who presented with hydrops fetalis during the second trimester of pregnancy. After prenatal evaluation revealed anemia of undetermined etiology, the fetus received intrauterine transfusion therapy. Despite successful treatment of the anemia and hydrops fetalis, in utero renal failure ensued. The infant died neonatally. Postmortem examination of a bone marrow aspirate indicated Diamond-Blackfan anemia as the cause of the hydrops fetalis. CONCLUSION: Diamond-Blackfan anemia may be an unrecognized cause of hydrops fetalis. The suboptimal outcome in this case underscores the larger issue of apparently successful treatment of in utero anemia with little or no impact on postnatal survival.

Adolescent↗

PubMed1993

The hemodynamic effects of isometric exercise during late normal pregnancy.

OBJECTIVE: Our study was designed to evaluate the hemodynamic effects of isometric exercise in late normal pregnancy. STUDY DESIGN: Study subjects were 10 healthy pregnant volunteers with uncomplicated singleton gestations between 25 and 36 weeks. Doppler methods were used to derive cardiac output, total peripheral resistance, and stroke volume before, during, and after a defined protocol of lower extremity isometric exercise. Hemodynamics and blood pressure were evaluated and compared. RESULTS: Mean arterial blood pressure and total peripheral resistance increased during the performance of isometric effort (mean blood pressure +/- SD was 78.9 +/- 7.3 to 97.5 +/- 8.6 mm Hg; total peripheral resistance +/- SD was 924 +/- 148 to 1153 +/- 18.3 dyne.sec.cm-5; p < 0.002 and p < 0.001, respectively). Cardiac output remained unchanged throughout the study period. CONCLUSION: In advanced normal pregnancy isometric exercise increases the mean arterial blood pressure by raising the total peripheral resistance.

Blood Pressure↗

PubMed1991

Leuprolide acetate stimulates smooth muscle of the human reproductive tract.

Leuprolide acetate (10(-4) to 10(-5) M) had a stimulatory effect on spontaneous contractions of human myometrium and fallopian tube in vitro. The uterine and tubal tissues were from patients with dysfunctional uterine bleeding that was treated by hysterectomy. Whether the effect of LA on smooth muscle is a component of the mechanism of therapeutic action or an undesirable side effect remains to be determined.

Digestive System↗

PubMed1991

Endocrine crises. Hypermagnesemia.

Hypermagnesemia is an often-overlooked problem in acute medical care situations. Magnesium is used in several areas of medicine and for various reasons. It also is found in many seemingly innocuous cathartics and gastrointestinal medications. Magnesium replacement in enteral or parenteral feeding and magnesium deficiency is addressed often. Despite the necessity to consider magnesium in several situations, many physicians are relatively unfamiliar with the use of magnesium in their patients. Magnesium is often used in patients with renal insufficiency, which further increases the risk of hypermagnesemia. Fortunately, the evaluation and treatment of hypermagnesemia is relatively straightforward. Calcium reversal of life-threatening sequelae, diuresis or dialysis to augment elimination of magnesium, and supportive care until the acute manifestations of the disorder resolve are the mainstays of therapy for hypermagnesemia. Recognition of patients at risk for the disorder and careful consideration of magnesium therapy will allow for prevention or early diagnosis of the disorder.

Adult↗