Kenneth Chan

Effects of maternal obesity on tissue concentrations of prophylactic cefazolin during cesarean delivery.

OBJECTIVE: To estimate the adequacy of antimicrobial activity of preoperative antibiotics at the time of cesarean delivery as a function of maternal obesity. METHODS: Twenty-nine patients scheduled for cesarean delivery were stratified according to body mass index (BMI) category, with 10 study participants classified as lean (BMI less than 30), 10 as obese (BMI 30–39.9), and nine as extremely obese (BMI 40 or higher). All patients were given a dose of 2 g cefazolin 30–60 minutes before skin incision. Antibiotic concentrations from adipose samples, collected after skin incision and before skin closure, along with myometrial and serum samples, were analyzed with microbiological agar diffusion assay. RESULTS: Cefazolin concentrations within adipose tissue obtained at skin incision were inversely proportional to maternal BMI (r=−0.67, P<.001). The mean adipose concentration was 9.4 plus or minus 2.7 micrograms/g in the lean group of women compared with 6.4 plus or minus 2.3 micrograms/g in the obese group (P=.009) and 4.4 plus or minus 1.2 micrograms/g in the extremely obese group (P<.001). Although all specimens demonstrated therapeutic cefazolin levels for gram-positive cocci (greater than 1 microgram/g), a considerable portion of obese and extremely obese did not achieve minimal inhibitory concentrations of greater than 4 micrograms/g for Gram-negative rods in adipose samples at skin incision (20% and 33.3%, respectively) or closure (20.0% and 44.4%, respectively). No significant difference in cefazolin concentration was observed in mean closure adipose, myometrial, or serum specimens across the BMI categories. CONCLUSION: Pharmacokinetic analysis suggests that present antibiotic prophylaxis dosing may fail to provide adequate antimicrobial coverage in obese patients during cesarean delivery. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00980486. LEVEL OF EVIDENCE: II

Interdelivery interval and the success of vaginal birth after cesarean delivery

OBJECTIVE To determine whether a short interdelivery interval is associated with decreased rate of successful vaginal birth after cesarean (VBAC). METHODS A retrospective cohort study from January 1, 1997, to December 31, 2000, was conducted. Patients with previous cesarean delivery who attempted VBAC were identified. The analysis was limited to patients at term with one prior cesarean. The interdelivery interval was calculated in months between the index pregnancy and prior cesarean delivery. RESULTS A total of 1516 subjects who attempted VBAC were identified among 24,162 deliveries, with complete data available in 1185 cases. The VBAC success rate was 79.0% for patients with an interdelivery interval less than 19 months compared with 85.5% for patients with an interval delivery greater than or equal to 19 months (P = .12). For patients whose labors were induced, interdelivery intervals of less than 19 months were associated with a decreased rate of VBAC success when compared with longer intervals (P < .01). Sufficient power (β = .95) existed to detect a 64% difference between the groups (&agr; = .05). No significant difference was detected in women who underwent spontaneous labor (P = .98). There was no difference in the rate of symptomatic uterine rupture (P = 1.00). CONCLUSION Interdelivery intervals of less than 19 months were associated with a decreased rate of VBAC success in patients who underwent induction, a difference not found in those with spontaneous labor.

Longitudinal Changes in the B-Type Natriuretic Peptide Levels in Normal Pregnancy and Postpartum

Normal levels of B‐type natriuretic peptide (BNP) are not well established in pregnancy. We obtained longitudinal BNP levels in 29 healthy pregnant women in each trimester and postpartum period, and compared these levels to the 25 nonpregnant controls. There were no significant differences among the cases and controls with respect to weight, diastolic blood pressure, and ethnicity. A total of 116 BNP values were obtained during pregnancy. The median (and range) BNP level during pregnancy was 19 (10–143) pg/ml versus 10 (10–37) pg/ml in the nonpregnant controls (p = 0.003). However, there were no statistically significant differences in the median BNP levels at various stages of pregnancy: first trimester 20 (10–115) pg/ml versus the second trimester 18 (10–112) pg/ml (p = 0.8), second trimester 18 pg/ml versus third trimester 26 (10–143) pg/ml (p = 0.06), and third trimester 26 pg/ml versus postpartum18 (10–62) pg/ml (p = 0.08). There were no significant differences between the BNP levels throughout the trimesters and postpartum period. Pregnant BNP levels were approximately twice as high as the nonpregnant BNP levels. Our study is unique in evaluating longitudinal changes in BNP levels in normal pregnancies and the postpartum period in comparison with healthy, nonpregnant controls. It demonstrates that pregnant BNP levels are approximately 2‐fold higher than their nonpregnant counterparts, and do not significantly fluctuate during pregnancy. In conclusion, pregnancy is associated with a significant, but small increase in the BNP levels compared with nonpregnant women. Copyright

A randomized, double-blinded, controlled trial comparing parenteral normal saline with and without dextrose on the course of labor in nulliparas

OBJECTIVEnThe objective of the study was to compare intravenous normal saline with and without dextrose on the course of labor in nulliparae.nnnSTUDY DESIGNnIn a double-blinded, controlled trial, term, nulliparae with singletons in active labor were randomized into 1 of 3 groups receiving either normal saline (NS), NS with 5% dextrose (D5NS), or NS with 10% dextrose (D10NS) at 125 mL/h. The primary outcome was total length of labor from onset of study fluid in vaginally delivered subjects. Maternal and neonatal outcomes were also analyzed.nnnRESULTSnOf 300 subjects enrolled, 289 met inclusion criteria and completed the study. In vaginally delivered subjects, significant differences were noted in the second stage (P = .01) and total length of labor (P = .02). No significant differences were observed in the cesarean section rates between the groups (P = .21). No differences were noted in maternal or neonatal secondary outcomes.nnnCONCLUSIONnAdministration of a dextrose solution, regardless of concentration, was associated with a shortened labor course in term vaginally delivered nulliparae subjects in active labor.

Nitric oxide and carbon monoxide production and metabolism in preeclampsia.

Objective: To elucidate the regulation of the nitric oxide (NO) and carbon monoxide (CO) pathways in preeclampsia and to evaluate the ratio of asymmetric dimethylarginine (ADMA) to symmetric dimethylarginine (SDMA) as a marker for preeclampsia. Methods: Maternal plasma and placental samples were obtained from 20 participants with preeclampsia and 23 controls. Enzyme-linked immunosorbent assay was used to measure plasma NO, ADMA, and SDMA as well as placental NO and hemeoxygnase 1 (HO-1). Western blot was used to measure placental dimethylarginine dimethylaminotransferases (DDAH-I and DDAH-II). Results: Placental DDAH-I, placental DDAH-II, placental NO, and placental HO-1 were significantly decreased in participants with preeclampsia. While ADMA and SDMA levels were decreased in preeclampsia, the ADMA-SDMA ratio was not significantly different. Conclusions: Decreased DDAH and HO with preeclampsia suggest that they are important points in the regulatory pathways of NO and CO production that are altered in preeclampsia. The ADMA-SDMA ratio is not a useful test for preeclampsia.

A randomized, double-masked trial of prophylactic indomethacin tocolysis versus placebo in women with premature rupture of membranes.

Preterm premature rupture of membranes (PPROM) complicates 3% of pregnancies and frequently results in preterm birth, often within 48 hours of membrane rupture. Our objective was to determine if subjects with PPROM between 24 and 31 (6)/ (7) weeks gestation benefit from a 48-hour course of prophylactic indomethacin tocolysis. This was a double-masked randomized controlled trial. Subjects with PPROM between 24 and 31 (6)/ (7) weeks gestation were randomized to receive indomethacin or placebo for 48 hours in addition to corticosteroids and latency antibiotics. The primary outcome of the study was delivery within 48 hours. Maternal and neonatal outcomes were also compared. This study was concluded prematurely due to slow accrual after a total of 50 subjects were enrolled. A total of 23/25 (92%) subjects in the indomethacin group remained pregnant beyond 48 hours compared with 20/22 (90.9%) in the placebo group (relative risk, 1.01; 95% confidence interval, 0.84 to 1.21). The latency period medians and interquartile ranges were similar between the two groups [indomethacin 193 (92 to 376.5) hours versus placebo 199 (77.5 to 459) hours, P = 0.91], and no differences were noted in any maternal or neonatal secondary outcomes. This limited study demonstrates no benefit with the use of prophylactic indomethacin tocolysis for women with PPROM.

Women's attitudes regarding mode of delivery and cesarean delivery on maternal request

Objective.u2003To explore womens attitudes and beliefs regarding cesarean delivery and cesarean delivery on maternal request (CDMR). Study design.u2003Anonymous questionnaires assessing patient demographics, knowledge, and attitudes about CDMR were distributed at the time of routine mid-trimester ultrasound appointment. Results.u2003Eight hundred thirty three out of 3929 (21.2%) potential participants completed the questionnaire. About 81.7% of participants indicated that they believed that vaginal delivery was a safer alternative for the mother and 72.8% believed that it was safer for the fetus. While only 6.1% of women thought that CDMR was ‘a good idea’, most believed that women should have the right to choose their mode of delivery and that the option should be offered to everyone (85.9% and 79.6%, respectively). Socioeconomic and demographic variables did not significantly influence the participants responses. Conclusion.u2003Majority of women believe that vaginal delivery is safer for the mother and baby and would prefer to have a vaginal delivery if given the option.