Effects of maternal glucose infusion on fetal acid-base status in human pregnancy

Intraoperative use of balanced crystalloids versus 0.9% saline: a systematic review and meta-analysis of randomised controlled studies

BACKGROUND

The evidence regarding optimal crystalloid use in the perioperative period remains unclear. As the primary aim of this study, we sought to summarise the data from RCTs examining whether use of balanced crystalloids compared with 0.9% saline (saline) leads to differences in patient-important outcomes.

METHODS

We searched Ovid MEDLINE, Embase, the Cochrane library, and Clinicaltrials.gov, from inception until December 15, 2022, and included RCTs that intraoperatively randomised adult participants to receive either balanced fluids or saline. We pooled data using a random-effects model and present risk ratios (RRs) or mean differences (MDs), along with 95% confidence intervals (CIs). We assessed individual study risk of bias using the modified Cochrane tool, and certainty of evidence using GRADE.

RESULTS

Of 5959 citations, we included 38 RCTs (n=3776 patients). Pooled analysis showed that intraoperative use of balanced fluids compared with saline had an uncertain effect on postoperative mortality analysed at the longest point of follow-up (RR 1.51, 95% CI: 0.42-5.36) and postoperative need for renal replacement therapy (RR 0.95, 95% CI: 0.56-1.59), both very low certainty. Furthermore, use of balanced crystalloids probably leads to a higher postoperative serum pH (MD 0.05, 95% CI: 0.04-0.06), moderate certainty.

CONCLUSIONS

Use of balanced crystalloids, compared with saline, in the perioperative setting has an uncertain effect on mortality and need for renal replacement therapy but probably improves postoperative acid-base status. Further research is needed to determine whether balanced crystalloid use affects patient-important outcomes.

CLINICAL TRIAL REGISTRATION

CRD42022367593.

Fetoplacental oxygen homeostasis in pregnancies with maternal diabetes mellitus and obesity

Despite improvements in clinical management, pregnancies complicated by pre-existing diabetes mellitus, gestational diabetes mellitus or obesity carry substantial risks for parent and offspring. Some of the endocrine and metabolic changes in parent and fetus in diabetes mellitus and obesity lead to fetal oxygen deficit, mostly due to insulin-induced accelerated fetal metabolism. The human fetus deals with reduced oxygenation through a wide range of adaptive responses that act at various levels in the placenta as well as the fetus. These responses ensure adequate oxygen delivery to the fetus, increase the oxygen transport capacity of fetal blood and redistribute oxygen-rich blood to vital organs such as the brain and heart. The liver has a central role in adapting to reduced oxygenation by increasing its oxygen extraction and stimulating erythropoietin synthesis to increase haematocrit. The type of adaptive response depends on the onset and duration of hypoxia and the severity of the metabolic disturbance. In pregnancies characterized by diabetes mellitus or obesity, these adaptive systems come under additional strain owing to the increased maternal supply of glucose and resultant fetal hyperinsulinaemia, both of which stimulate oxidative metabolism. In the rare situation that the adaptive responses are overwhelmed, stillbirth can ensue.

Efficacy and safety of the pregnancy-IVI, an intravenous insulin protocol for pregnancy, following antenatal betamethasone in type 1 and type 2 diabetes

AIMS

Hyperglycaemia following antenatal corticosteroids is common in women with diabetes in pregnancy, and validated algorithms to maintain pregnancy-specific glucose targets are lacking. The Pregnancy-IVI, an intravenous-insulin (IVI) algorithm, has been validated in gestational diabetes; however, its performance in pre-existing diabetes (Type 1 and Type 2 diabetes) is not known. We hypothesised that Pregnancy-IVI would be superior to a generic Adult-IVI protocol (prior standard of care) following betamethasone in women with pre-existing diabetes.

METHODS

A retrospective cohort study enrolled all women with pre-existing diabetes at a tertiary centre receiving betamethasone and treated with IVI according to one of two protocols: Adult-IVI (n = 73, 2014-2017) or Pregnancy-IVI (n = 62, 2017-2020). The primary outcome was on-IVI glycaemic time-in-range (capillary blood glucose (BGL) 3.8-7.0 mmol/L). Secondary outcomes included time with critical hyperglycaemia (BGL > 10 mmol/L); occurrence of maternal hypoglycaemia (BGL < 3.8 mmol/l) and incidence of neonatal hypoglycaemia (BGL ≤ 2.5 mmol/L). Analysis was stratified by diabetes type.

RESULTS

Overall, Pregnancy-IVI achieved a higher proportion of on-IVI time-in-range (70%, IQR 56-78%) compared to Adult-IVI (52%, IQR 41-69%, p < 0.0001). The duration of critical hyperglycaemia with Pregnancy-IVI was also reduced (2% [IQR 0-7] vs 8% [IQR 4-17], p < 0.0001), without an increase in hypoglycaemia. Glycaemic variability was significantly reduced with Pregnancy-IVI. No difference in the rate of neonatal hypoglycaemia was observed. The Pregnancy-IVI was most effective in women with Type 1 diabetes.

CONCLUSION

The Pregnancy-IVI algorithm is safe and effective when used following betamethasone in type 1 diabetes in pregnancy. Further study of women with type 2 diabetes is required.

Comparison of a subcutaneous versus intravenous insulin protocol for managing hyperglycemia following antenatal betamethasone in women with diabetes: a pilot randomized controlled trial

INTRODUCTION

Evaluate the safety and efficacy of a subcutaneous insulin (SC-I) versus intravenous insulin (IV-I) protocol for optimizing maternal blood glucose levels (BGLs) post-betamethasone administration.

METHODS

Randomized controlled in-patient pilot study in pregnant women with diabetes, excluding type 1 diabetes, receiving betamethasone ≥24 weeks' gestation. Interventions were stratified SC-I and IV-I protocols, titrated to hourly BGLs (IV-I) or predicted maternal hyperglycemia and 2-4 hourly BGLs (SC-I). Primary outcome was percentage at-target BGL 4.0-8.0 mmol/L over 48 h post-betamethasone. Secondary outcomes were rates of maternal hyperglycemia (>8.0 mmol/L), hypoglycemia (<4.0 mmol/L) and neonatal hypoglycemia (≤2.5 mmol/L).

RESULTS

19 women (3 with type 2 diabetes [T2DM], 4 with gestational diabetes [GDM]-diet, 12 GDM-insulin) were randomized to a SC-I (n = 13) or IV-I (n = 6) protocol in a 9-month period. There was a non-significant trend for higher mean percentage at-target BGLs with SC-I vs IV-I (87% vs 81%; p = .055); this was significant when the cohort was restricted to women with GDM (89% vs 81%; p = .04). Maternal hyperglycemia (85% vs 100%; p = .31) and hypoglycemia (54% vs 33%; p = .41) were not significantly different, but there were no BGLs <3.8 mmol/L with IV-I (vs 4 women with SC-I; p = .13). The rate of neonatal hypoglycemia was not different between groups.

CONCLUSION

A SC-I or IV-I protocol controls maternal BGLs following betamethasone, but SC-I appears safe and minimizes labor intensive IV-I in GDM. An adequately powered RCT to assess superiority of SC-I is planned.

Prophylactic metformin after antenatal corticosteroids (PROMAC): a double blind randomized controlled trial

Background

Antenatal corticosteroids (ACS) are increasingly used to improve prematurity-related neonatal outcome. A recognized and common adverse effect from administration of antenatal corticosteroid is maternal hyperglycemia. Even normal pregnancy is characterized by relative insulin resistance and glucose intolerance. Treatment of maternal hyperglycemia after ACS might be indicated due to the higher risk of neonatal acidosis which may coincide with premature birth. Metformin is increasingly used to manage diabetes mellitus during pregnancy as it is effective and more patient friendly. There is no data on prophylactic metformin to maintain euglycemia following antenatal corticosteroids administration.

Methods

A double blind randomized trial. 103 women scheduled to receive two doses of 12-mg intramuscular dexamethasone 12-hour apart were separately randomized to take prophylactic metformin or placebo after stratification according to their gestational diabetes (GDM) status. First oral dose of allocated study drug was taken at enrolment and continued 500 mg twice daily for 72 hours if not delivered. Six-point blood sugar profiles were obtained each day (pre- and two-hour post breakfast, lunch and dinner) for up to three consecutive days. A hyperglycemic episode is defined as capillary glucose fasting/pre-meal ≥ 5.3 mmol/L or two-hour post prandial/meal ≥ 6.7 mmol/L. Primary outcome was hyperglycemic episodes on Day-1 (first six blood sugar profile points) following antenatal corticosteroids.

Results

Number of hyperglycemic episodes on the first day were not significantly different (mean ± standard deviation) 3.9 ± 1.4 (metformin) vs. 4.1 ± 1.6 (placebo) p = 0.64. Hyperglycemic episodes markedly reduced on second day in both arms to 0.9 ± 1.0 (metformin) vs. 1.2 ± 1.0 (placebo) p = 0.15 and further reduced to 0.6 ± 1.0 (metformin) vs. 0.7 ± 1.0 (placebo) p = 0.67 on third day. Hypoglycemic episodes during the 3-day study period were few and all other secondary outcomes were not significantly different.

Conclusions

In euglycemic and diet controllable gestational diabetes mellitus women, antenatal corticosteroids cause sustained maternal hyperglycemia only on Day-1. The magnitude of Day-1 hyperglycemia is generally low. Prophylactic metformin does not reduce antenatal corticosteroids’ hyperglycemic effect.

Trial registration

The trial is registered in the ISRCTN registry on May 4 2017 with trial identifier 10.1186/ISRCTN10156101.

Patterns of antenatal corticosteroid administration in a cohort of women with diabetes in pregnancy

Antenatal corticosteroids administered to the mother prior to birth decrease the risk of mortality and major morbidity in infants born at less than 35 weeks’ gestation. However, the evidence relating to women with diabetes in pregnancy is limited. Clinical guidelines for antenatal corticosteroid administration recommend that women with diabetes in pregnancy are treated in the same way as women without diabetes, but there are no recent descriptions of whether contemporary practice complies with this guidance. This study is a retrospective review of antenatal corticosteroid administration at a New Zealand tertiary hospital in women with diabetes in pregnancy. We found that in this cohort, for both an initial course at less than 35 weeks’ gestation and repeat courses at less than 33 weeks’, the administration of antenatal corticosteroid to women with diabetes in pregnancy is largely consistent with current Australian and New Zealand recommendations. However, almost 25% of women received their last dose of antenatal corticosteroid at or beyond the latest recommended gestation of 35 weeks’ gestation. Pre-existing diabetes and planned caesarean section were independently associated with an increased rate of antenatal corticosteroid administration. We conclude that diabetes in pregnancy does not appear to be a deterrent to antenatal corticosteroid administration. The high rates of administration at gestations beyond recommendations, despite the lack of evidence of benefit in this group of women, highlights the need for further research into the risks and benefits of antenatal corticosteroid administration to women with diabetes in pregnancy, particularly in the late preterm and early term periods.

An intravenous insulin protocol designed for pregnancy reduces neonatal hypoglycaemia following betamethasone administration in women with gestational diabetes

AIMS

Marked hyperglycaemia is common following betamethasone administration in women with gestational diabetes (GDM), and may contribute to neonatal hypoglycaemia. Validated protocols to deliver glycaemic stability following betamethasone are lacking. We hypothesized that an intravenous insulin (IVI) protocol for pregnancy-specific glycaemic targets (Pregnancy-IVI) would achieve greater at-target glycaemic control than a generic adult intravenous insulin protocol (Adult-IVI), and may reduce neonatal hypoglycaemia.

METHODS

A retrospective cohort study of the performance Adult-IVI and Pregnancy-IVI following betamethasone in GDM, sequentially implemented at a tertiary hospital, without change in indication for IVI. Cases were identified by electronic record search. Primary outcome was percentage of on-IVI time with at-target glycaemia [blood glucose level (BGL) 3.8-7 mmol/l]. Secondary outcomes were time with critical hyperglycaemia (BGL > 10 mmol/l), occurrence of maternal hypoglycaemia (BGL < 3.8 mmol/l), and incidence of neonatal hypoglycaemia (BGL ≤ 2.5 mmol/l) if betamethasone was administered within 48 h of birth.

RESULTS

The cohorts comprised 151 women (Adult-IVI n = 86; Pregnancy-IVI n = 65). The primary outcome was 68% time-at-target [95% confidence interval (CI) 64-71%) for Pregnancy-IVI compared with 55% (95% CI 50-60%) for Adult-IVI (P = 0.0002). Critical maternal hyperglycaemia (0% vs. 2%, P = 0.02) and hypoglycaemia (2% vs. 12%, P = 0.02) were both lower with Pregnancy-IVI than Adult-IVI. Neonatal hypoglycaemia was less common after Pregnancy-IVI (29%) than after Adult-IVI (54%, P = 0.03). A multiple logistic regression model adjusting for potential confounders gave an odds ratio for neonatal hypoglycaemia with Pregnancy-IVI of 0.27 (95% CI 0.10-0.76, P = 0.01).

CONCLUSIONS

An IVI protocol designed for pregnancy effectively controlled maternal hyperglycaemia following betamethasone administration in GDM. This is the first intervention to show a reduction in betamethasone-associated neonatal hypoglycaemia, linked with optimum maternal glycaemic control.

Reduction of total labor length through the addition of parenteral dextrose solution in induction of labor in nulliparous: results of DEXTRONS prospective randomized controlled trial

BACKGROUND

Prolonged labor is a significant cause of maternal and fetal morbidity and very few interventions are known to shorten labor course. Skeletal muscle physiology suggests that glucose supplementation might improve muscle performance in case of prolonged exercise and this situation is analogous to the gravid uterus during delivery. Therefore, it seemed imperative to evaluate the impact of adding carbohydrate supplements on the course of labor.

OBJECTIVE

We sought to provide evidence as to whether intravenous glucose supplementation during labor induction in nulliparous women can reduce total duration of active labor.

STUDY DESIGN

We performed a single-center prospective double-blind randomized controlled trial comparing the use of parental intravenous dextrose 5% with normal saline to normal saline in induced nulliparous women. The study was conducted in a tertiary-level university hospital setting. Participants, caregivers, and those assessing the outcomes were blinded to group assignment. Inclusion criteria were singleton pregnancy at term with cephalic presentation and favorable cervix. Based on blocked randomization, patients were assigned to receive either 250 mL/h of intravenous dextrose 5% with normal saline or 250 mL/h of normal saline for the whole duration of induction, labor, and delivery. The primary outcome studied was the total length of active labor. Secondary outcomes included duration of the active phase of second stage of labor, the mode of delivery, Apgar scores, and arterial cord pH.

RESULTS

In all, 100 patients were randomized into each group. A total of 193 patients (96 in the dextrose with normal saline group and 97 in the normal saline group) were analyzed in the study. The median total duration of labor was significantly less in the dextrose with normal saline group (499 vs 423 minutes, P = .024) than in the normal saline group. The probabilities of a woman being delivered at 200 minutes and 450 minutes were 18.8% and 77.1% in the dextrose with normal saline group vs 8.2% and 59.8% in the normal saline group (Kolmogorov-Smirnov test P value = .027). There was no difference in the rate of cesarean delivery, instrumented delivery, Apgar score, or arterial cord pH.

CONCLUSION

Glucose supplementation significantly reduces the total length of labor without increasing the rate of complication in induced nulliparous women. Given the low cost and the safety of this intervention, glucose should be used as the default solute during labor.

Effect of antenatal betamethasone on blood glucose levels in women with and without diabetes

OBJECTIVE

To characterize the maternal glycemic response to betamethasone in subjects without diabetes compared to subjects with diabetes.

STUDY DESIGN

Blood glucose levels in 22 gravidae without diabetes and 11 gravidae with diabetes were recorded for 48h following betamethasone administration for threatened preterm delivery. Maximum blood glucose value and time to maximum value were compared. Area under the curve calculations were used to express the duration and degree of significant hyperglycemia for individual subjects. These summary measures were then correlated to subject characteristics and laboratory values to determine a risk profile of those subjects without diabetes at risk for significant hyperglycemia.

RESULTS

All subjects with diabetes and the majority of those without diabetes had significant hyperglycemia during the study period. Mean maximum blood glucose was higher for those with diabetes (205mg/dL vs. 173mg/dL, p⩽0.01). Mean time to reach the maximum glucose level was similar for both groups. Result of a glucose tolerance test given immediately prior to betamethasone correlated strongly with amount of time spent with hyperglycemia for subjects without diabetes (rho=0.59, p⩽0.01). Morbidly obese subjects spent less time with hyperglycemia than those with lower body mass indices (p=0.03).

CONCLUSION

Both subjects with and without diabetes demonstrate significant hyperglycemia after receipt of antenatal betamethasone.

Influence of administration of 1 % glucose solution on neonatal blood glucose concentration in cesarean section

Perioperative administration of adequate glucose prevents hypercatabolism. However, excessive glucose administration until delivery of a fetus might cause newborn hypoglycemia in cesarean section. In this retrospective study, we investigated whether the administration of 1 % glucose solution during cesarean section influenced neonatal blood glucose concentration. We found 46 consecutive patients between 37 and 41 weeks of gestation who underwent cesarean section under combined epidural and spinal anesthesia. We divided the patients into two groups: those receiving 1 % glucose solution (group A, N = 23) and those receiving a solution without glucose (group B, N = 23) until delivery. We recorded umbilical cord blood glucose on delivery, neonatal blood glucose level 3 h after delivery, and 1- and 5-min Apgar scores. The dose of glucose administered until delivery of fetus in group A was 3.6 ± 1.7 mg/kg/min [mean ± standard deviation (SD)] and that in group B 0 mg/kg/min. Umbilical cord blood glucose concentration on delivery of fetus in group A was significantly higher than that in group B (101 ± 19 vs. 66 ± 10 mg/dl; P < 0.0001). Neonatal blood glucose level 3 h after delivery was not significantly different between groups (90 ± 15 vs. 90 ± 21 mg/dl; P = 0.96). The 1- and 5-min Apgar scores were similar between groups. In conclusion, administration of 1 % glucose solution in cesarean section might contribute to prevention of neonatal hypoglycemia.

Perioperative glycaemic control for diabetic patients undergoing surgery

BACKGROUND

Patients with diabetes mellitus are at increased risk of postoperative complications. Data from randomised clinical trials and meta-analyses point to a potential benefit of intensive glycaemic control, targeting near-normal blood glucose, in patients with hyperglycaemia (with and without diabetes mellitus) being submitted to surgical procedures. However, there is limited evidence concerning this question in patients with diabetes mellitus undergoing surgery.

OBJECTIVES

To assess the effects of perioperative glycaemic control for diabetic patients undergoing surgery.

SEARCH METHODS

Trials were obtained from searches of The Cochrane Library, MEDLINE, EMBASE, LILACS, CINAHL and ISIS (all up to February 2012).

SELECTION CRITERIA

We included randomised controlled clinical trials that prespecified different targets of perioperative glycaemic control (intensive versus conventional or standard care)

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. We summarised studies using meta-analysis or descriptive methods.

MAIN RESULTS

Twelve trials randomised 694 diabetic participants to intensive control and 709 diabetic participants to conventional glycaemic control. The duration of the intervention ranged from just the duration of the surgical procedure up to 90 days. The number of participants ranged from 13 to 421, and the mean age was 64 years. Comparison of intensive with conventional glycaemic control demonstrated the following results for our predefined primary outcomes: analysis restricted to studies with low or unclear detection or attrition bias for infectious complications showed a risk ratio (RR) of 0.46 (95% confidence interval (CI) 0.18 to 1.18), P = 0.11, 627 participants, eight trials, moderate quality of the evidence (grading of recommendations assessment, development and evaluation - (GRADE)). Evaluation of death from any cause revealed a RR of 1.19 (95% CI 0.89 to 1.59), P = 0.24, 1365 participants, 11 trials, high quality of the evidence (GRADE).On the basis of a posthoc analysis, there is the hypothesis that intensive glycaemic control may increase the risk of hypoglycaemic episodes if longer-term outcome measures are analysed (RR 6.92, 95% CI 2.04 to 23.41), P = 0.002, 724 patients, three trials, low quality of the evidence (GRADE). Analysis of our predefined secondary outcomes revealed the following findings: cardiovascular events had a RR of 1.03 (95% CI 0.21 to 5.13), P = 0.97, 682 participants, six trials, moderate quality of the evidence (GRADE) when comparing the two treatment modalities; and renal failure also did not show significant differences between intensive and regular glucose control (RR 0.61, 95% CI 0.34 to 1.08), P = 0.09, 434 participants, two trials, moderate quality of the evidence (GRADE). We did not meta-analyse length of hospital stay and intensive care unit (ICU) stay due to substantial unexplained heterogeneity. Mean differences between intensive and regular glucose control groups ranged from -1.7 days to 2.1 days for ICU stay and between -8 days to 3.7 days for hospital stay (moderate quality of the evidence (GRADE)). One trial assessed health-related quality of life in 12/37 (32.4%) of participants in the intervention group and 13/44 (29.5%) of participants in the control group, and did not show an important difference (low quality of the evidence (GRADE)) in the measured physical health composite score of the short-form 12-item health survey (SF-12). None of the trials examined the effects of the interventions in terms of costs.

AUTHORS' CONCLUSIONS

The included trials did not demonstrate significant differences for most of the outcomes when targeting intensive perioperative glycaemic control compared with conventional glycaemic control in patients with diabetes mellitus. However, posthoc analysis indicated that intensive glycaemic control was associated with an increased number of patients experiencing hypoglycaemic episodes. Intensive glycaemic control protocols with near-normal blood glucose targets for patients with diabetes mellitus undergoing surgical procedures are currently not supported by an adequate scientific basis. We suggest that insulin treatment regimens, patient- and health-system relevant outcomes, and time points for outcome measures should be defined in a thorough and uniform way in future studies.

Maternal Hyperglycemia Disrupts Histone 3 Lysine 36 Trimethylation of the IGF-1 Gene

In utero environmental adaptation may predispose to lifelong morbidity. Organisms fine-tune gene expression to achieve environmental adaptation by epigenetic alterations of histone markers of gene accessibility. One example of epigenetics is how uteroplacental insufficiency-induced intrauterine growth restriction (IUGR), which predisposes to adult onset insulin resistance, decreases postnatal IGF-1 mRNA variants and the gene elongation mark histone 3 trimethylation of lysine 36 of the IGF-1 gene (H3Me3K36). Limitations in the study of epigenetics exist due to lack of a primary transgenic epigenetic model. Therefore we examined the epigenetic profile of insulin-like growth factor 1 (IGF-1) in a well-characterized rat model of maternal hyperglycemia to determine if the epigenetic profile of IGF-1 is conserved in disparate models of in utero adaptation. We hypothesized that maternal hyperglycemia would increase IGF-1 mRNA variants and H3Me3K36. However maternal hyperglycemia decreased hepatic IGF-1 mRNA variants and H3Me3K36. This finding is intriguing given that despite different prenatal insults and growth, both maternal hyperglycemia and IUGR predispose to adult onset insulin resistance. We speculate that H3Me3K36 of the IGF-1 gene is sensitive to the glucose level of the prenatal environment, with resultant alteration of IGF-1 mRNA expression and ultimately vulnerability to adult onset insulin resistance.

Hypovolaemia after glucose/insulin infusions in volunteers

High-dose intravenous infusion of 5% glucose promotes rebound hypoglycaemia and hypovolaemia in healthy volunteers. To study whether such effects occur in response to glucose/insulin, 12 healthy firemen (mean age, 39 years) received three infusions over 1-2 h that contained 20 ml of 2.5% glucose/kg of body weight, 5 ml of 10% glucose/kg of body weight with 0.05 unit of rapid-acting insulin/kg of body weight, and 4 ml of 50% glucose/kg of body weight with 1 unit of insulin/kg of body weight. The plasma glucose concentration and plasma dilution were compared at 5-10 min intervals over 4 h. Regardless of the amount of administered fluid and whether insulin was given, the plasma glucose concentration decreased to hypoglycaemic levels within 30 min of the infusion ending. The plasma dilution closely mirrored plasma glucose and became negative by approx. 5%, which indicates a reduction in the plasma volume. These alterations were only partially restored during the follow-up period. A linear relationship between plasma glucose and plasma dilution was most apparent when the infused glucose had been dissolved in only a small amount of fluid. For the strongest glucose/insulin solution, this linear relationship had a correlation coefficient of 0.77 (n=386, P<0.0001). The findings of the present study indicate that a redistribution of water due to the osmotic strength of the glucose is the chief mechanism accounting for the hypovolaemia. It is concluded that infusions of 2.5%, 10% and 50% glucose, with and without insulin, in well-trained men were consistently followed by long-standing hypoglycaemia and also by hypovolaemia, which averaged 5%. These results emphasize the relationship between metabolism and fluid balance.

Maternal glucose levels after dexamethasone for fetal lung development in twin vs singleton pregnancies

OBJECTIVE

Betamethasone administration in singleton pregnancies causes maternal hyperglycemia. With the increased risk of glucose intolerance in twin pregnancies, we sought to determine whether maternal hyperglycemia after dexamethasone administration is different in twin vs singleton pregnancies.

STUDY DESIGN

Patients with singleton or twin pregnancies admitted between 24 and 34 weeks' gestation with diagnoses requiring steroid administration were approached. Exclusion criteria included diabetes, abnormal glucose tolerance test, infection, or medications known to interfere with glucose metabolism. Patients were NPO for 24 hours and received dexamethasone per protocol. Maternal glucose levels were checked at baseline and then at specified intervals after the initial dose; appropriate statistical analysis was performed.

RESULTS

Ten singleton and 9 twin gestations were enrolled. There were no differences in mean maternal or gestational ages. Mean glucose levels were significantly higher in the twin group at 4 hours (114 mg/dL vs 95.6 mg/dL), 8 hours (121.4 mg/dL vs 90.9 mg/dL), and 24 hours (116 mg/dL vs 81 mg/dL) (P < .01 for all).

CONCLUSION

Twin pregnancies had higher mean glucose values than singleton pregnancies in the first 24 hours after dexamethasone administration.

Intrapartum maternal glucose infusion and fetal acid-base status

OBJECTIVE

To compare the effects of an intrapartum infusion of a lactated Ringer solution or a glucose-boosted saline solution on the acid-base status of umbilical arterial blood.

METHOD

In a prospective clinical trial 178 women in labor were randomized to receive intravenously either a lactated Ringer solution or a saline solution boosted with 5% glucose. Umbilical arterial blood was then assessed for acid-base status.

RESULTS

There were significant differences between the lactated Ringer group and the glucose group in umbilical artery pH values (7.25+/-0.07 vs. 7.28+/-0.06; P=0.008), pCO2 values (44.8+/-5.6 mm Hg vs. 41.6+/-4.1 mm Hg; P=0.001), and base excess (-7.3+/-2.1 mEq/L vs. -6.6+/-1.8 mEq/L; P=0.02).

CONCLUSION

Intrapartum intravenous fluid containing a 5% glucose solution reduces umbilical cord acidemia and hypercarbia.

Carbohydrate solution intake during labour just before the start of the second stage: a double-blind study on metabolic effects and clinical outcome

OBJECTIVE

To study the effects of oral carbohydrate ingestion on clinical outcome and on maternal and fetal metabolism.

DESIGN

Prospective, double-blind, randomised study.

SETTING

Leyenburg Hospital, The Hague, The Netherlands.

POPULATION

Two hundred and two nulliparous women.

METHODS

In labour, at 8 to 10 cm of cervical dilatation, the women were asked to drink a solution containing either 25 g carbohydrates or placebo. In a subgroup of 28 women, metabolic parameters were measured.

MAIN OUTCOME MEASURES

Number of instrumental deliveries, fetal and maternal glucose, free fatty acids, lactate, pH, Pco2, base excess/deficit and beta-hydroxybutyrate.

RESULTS

Drinking a carbohydrate-enriched solution just before starting the second stage of labour did not reduce instrumental delivery rate (RR 1.1, 95% CI 0.9-1.3). Caesarean section rate was lower in the carbohydrate group, but the difference did not reach statistical significance (1% vs 7%, RR 0.2, 95% CI 0.02-1.2). In the carbohydrate group, maternal free fatty acids decreased and the lactate increased. In the umbilical cord there was a positive venous-arterial lactate difference in the carbohydrate group and a negative one in the placebo group, but the differences in pH and base deficit were comparable.

CONCLUSION

Intake of carbohydrates just before the second stage does not reduce instrumental delivery rate. The venous-arterial difference in the umbilical cord suggested lactate transport to the fetal circulation but did not result in fetal acidaemia.

Effects of obstetric analgesics and anesthetics on the neonate : a review

Most anesthetic and analgesic agents in current use traverse the placental barrier in varying degrees, but are well tolerated by the fetus if judiciously administered. For labor analgesia, many options are available. Systemic administration of opioids and sedatives is one such option. Repeated maternal administration of opioids such as pethidine (meperidine) results in significant fetal exposure and neonatal respiratory depression. Patient-controlled analgesia with synthetic opioids such as fentanyl, alfentanil, and the new ultra-short-acting remifentanil may be used for labor analgesia in selected patients. Other options for labor analgesia include epidural and combined spinal-epidural techniques. With such techniques, neonatal exposure to opioids and sedatives can be minimized or totally avoided. While limiting the fetal exposure to the harmful effects of depressant drugs, epidural anesthesia and/or analgesia improves placental perfusion and oxygenation of the fetus, which is beneficial, especially in conditions such as pregnancy-induced hypertension. Regional blocks are also administered for the majority of cesarean deliveries because of the overwhelming and unequivocal evidence of maternal and fetal safety compared with general anesthesia for this indication. However, in some instances, administration of general anesthesia is unavoidable. Neonatal respiratory depression with low Apgar scores, and umbilical arterial and venous pH associated with general anesthesia, is often transient. A properly administered anesthetic, whether regional or general, has no significant adverse fetal or neonatal effects.

Computerized analysis of fetal heart rate indices during oral glucose tolerance test

AIMS

To study the effect of maternal glucose ingestion during a 100 g oral glucose tolerance test on fetal heart rate indices.

STUDY DESIGN

Prospective study including 50 pregnant patients with an abnormal glucose challenge test who underwent a 100 g glucose tolerance test at 26-28 weeks gestation. Fetal heart rate was recorded and analyzed with the computerized Sonicaid Fetal Monitor System (Oxford 8000).

RESULTS

Baseline fetal heart rate significantly increased 120 and 180 minutes following glucose ingestion (p < 0.05) both in patients who were subsequently diagnosed to have gestational diabetes and in these in whom the diagnosis was excluded. No significant changes were noted in other fetal heart indices.

CONCLUSIONS

The significant and consistent increase in baseline fetal heart rate following maternal glucose ingestion indicates that the fetus responds to changes in its' environment. The exact mechanism which causes this response has yet to be defined.

Effect of the 100-g oral glucose tolerance test on fetal acid-base balance

OBJECTIVE

Previous studies have shown that maternal hyperglycemia may lead to fetal hypoxia and acidosis. The aim of the present study was to examine the impact of an oral 100-g glucose tolerance test on the fetal acid-base balance at mid-gestation.

METHODS

The study was conducted in healthy women who were scheduled for termination of pregnancy. The study group (n = 18) received an oral solution containing 100-g glucose and the control group (n = 18) received only water 1 h prior to termination of pregnancy. Termination of pregnancy was performed by fetal intracardiac injection of potassium chloride (KCl) and intraamniotic instillation of PGF2alpha. Acid-base variables were evaluated in the fetal blood and the amniotic fluid.

RESULTS

The glucose levels differed significantly between the study group and the control group with regard to maternal blood (127 +/- 28 versus 69 +/- 11 mg/dL, p < 0.001), fetal blood (128 +/- 24 versus 71 +/- 17 mg/dL, p < 0.001) and amniotic fluid (39 +/- 13 versus 28 +/- 5 mg/dL, p < 0.006). A linear relationship was found between maternal, fetal and amniotic fluid levels of glucose after maternal glucose ingestion. No significant changes were observed in the acid-base balance variables (pH, base excess, bicarbonate, lactate) in the fetal blood and the amniotic fluid of the study and control groups.

CONCLUSION

The 100-g oral glucose tolerance test has no adverse effect on the fetal acid-base balance when glucose levels reach a peak 1 h after the test in normal pregnancies.

The effects of oral carbohydrate administration on fetal acid base balance

AIMS

Little evidence-based data are available on the effects of eating and drinking during labor. Intravenous glucose administration has been related to fetal metabolic acidosis. The question is, whether oral intake of carbohydrates effects the fetal acid-base balance.

METHODS

In a double blind, prospective placebo controlled study 100 nulliparous women were randomized at 8-10 cm of cervical dilatation. All women were asked to drink 200 cc of either a carbohydrate solution (containing 25 grams carbohydrates) or placebo. In all women, both arterial and venous umbilical cord pH, pCO2, pO2, HCO3- and base excess/deficit were assessed. In a subgroup of women, whose deliveries were complicated by mild signs of fetal distress, clinical outcome and acid-base status was described separately.

RESULTS

Fetal arterial umbilical cord pH were identical: 7.20 +/- 0.07 in the placebo group and 7.20 +/- 0.08 in the carbohydrate group and the base excess -6.6 +/- 2.8 versus 6.6 +/- 3.7. In the women with mild signs of fetal distress, no differences were observed as well.

CONCLUSIONS

Oral carbohydrate intake during labor seems to be safe regarding the fetal acid-base balance. Further study on the maternal and fetal metabolic parameters is essential to give a more complete picture.

Volume kinetics of glucose solutions given by intravenous infusion

Glucose solutions given by intravenous (i.v.) infusion exert volume effects that are governed by the amount of fluid administered and also by the metabolism of the glucose. To understand better how the body handles glucose solutions, two volume kinetic models were developed in which consideration was given to the osmotic fluid shifts that accompany the metabolism of glucose. These models were fitted to data obtained when 21 volunteers who were given approximately 1 litre of glucose 2.5 or 5% or Ringer's solution (control) over 45 min. The maximum haemodilution was similar for all three fluids, but it decreased more rapidly when glucose had been infused. The volume of distribution for the infused glucose molecules was larger (approximately 12 litres) than for the infused fluid, which amounted to (mean (SEM)) 3.7 (0.3) (glucose 2.5%), 2.8 (0.2) (glucose 5%), and 2.5 (0.2) litres (Ringer). Fluid accumulated in a remote (cellular) body fluid space when glucose had been administered (approximately 0.2 and 0.4 litres, respectively), while expansion of an intermediate fluid space (7.1 (1.3) litres) could be demonstrated in 33% of the Ringer experiments. In conclusion, kinetic models were developed which consider the relationship between the glucose metabolism and the disposition of intravenous fluid. One of them, in which infused fluid expands two instead of three body fluid spaces, was successfully fitted to data on blood glucose and blood haemoglobin obtained during infusions of 2.5 and 5% glucose.

Glucocorticoid-associated maternal hyperglycemia: a randomized trial of insulin prophylaxis

OBJECTIVES

To study the degree and timing of maternal hyperglycemia following betamethasone therapy in nondiabetic patients and establish a prophylactic dose of insulin.

METHODS

Forty-five patients receiving betamethasone 12 mg i.m. at 7 AM on two consecutive days were randomized to no insulin (n = 20), low-dose insulin (n = 18), and high-dose insulin (n = 7) protocols. Each treatment group received s.c. insulin at 7 AM on the 2 days of betamethasone therapy (20 units NPH/10 units regular, and 40 units NPH/20 units regular, respectively). Capillary plasma glucose measurements were obtained at fasting and 2 h after meals for 3 days. A multivariate normal regression model was used to estimate and compare mean glucose levels.

RESULTS

Eighty-five percent of patients who did not receive insulin exhibited hyperglycemia at levels previously associated with fetal acidosis. Significant differences in mean postprandial plasma glucose levels were found between the no-treatment and insulin groups on days 1 and 2. No significant differences were noted between groups on day 3.

CONCLUSIONS

Transient maternal hyperglycemia occurs in a consistent pattern in nondiabetic patients receiving betamethasone, which can be limited by the concurrent use of insulin. Further studies to assess fetal acidosis in this setting are warranted.

Intravenous glucose infusion in labor does not affect maternal and fetal acid-base balance

OBJECTIVE

This prospective randomized trial compares the effects of a 5% glucose solution or no infusion during labor on glucose levels, pH, pO2, pCO2, and base excess (BE) of normal pregnant women in early labor and at delivery, and on fetal cord blood.

METHODS

Forty-three women were randomized to glucose infusion and 38 were controls.

RESULTS

Starting glucose levels were independent from the fasting state. When no glucose supplementation was given, the labor itself was associated with a reduction of mean pH (from 7.42 to 7.36, P = 0.00001), mean pCO2 (from 25.7 to 24.4 mm Hg, P = 0.04), and mean BE (from -6.3 to -9.8 mEq/L, P = 0.00001), and an increase of capillary glucose (from a mean of 83 to 105 mg/dL, P = 0.00001). Infusions of glucose did not significantly alter maternal acid-base balance at delivery. pH, PO2, pCO2, and BE were similar in arterial and venous cord blood of both groups. No variables correlated with cord blood glucose levels or with glucose vein-artery difference.

CONCLUSIONS

We conclude that a 5% glucose infusion does not significantly reduce maternal acidemia associated with vaginal delivery and therefore its use cannot be recommended, since maternal glucose is largely available during labor. Intrapartum glucose infusions do not alter the acid-base balance, when the fetus is well oxygenated.

Intrapartum tocolysis has no effect on fetal lactate concentration

OBJECTIVE

To assess the fetal metabolic effects of intrapartum maternal tocolysis with terbutaline in the presence of fetal heart rate abnormalities, with a special emphasis on lactate concentration, in view of its potential use as a marker of fetal condition.

DESIGN

Descriptive study.

SETTING

Two labour wards, National University Hospital, Singapore, and Ostersund Hospital, Sweden.

METHODS

Eight parturients with abnormal intrapartum fetal heart rate recordings were given bolus i.v. injection of 0.25 mg terbutaline and monitored both before and 20 minutes after treatment.

RESULTS

Maternal venous glucose increased from 5.0 (0.9) (mean (SD)) to 5.6 (1.2) mmol/l (p=0.002) and fetal scalp blood glucose rose from 4.1 (1.8) to 4.7 (1.4) mmol/l (p=0.009) 20 minutes after the injection. No significant change was found in maternal or fetal lactate concentrations.

CONCLUSION

Terbutaline tocolysis for "intrauterine resuscitation" does not affect fetal lactate concentration 20 minutes after treatment.

Lactate, lactate/pyruvate ratio and catecholamine interrelations in cord blood at delivery in complicated pregnancies

The interrelationships between lactate, lactate/pyruvate (L/P) ratio and catecholamines (CA) in cord artery and vein blood were studied in 56 pregnancies who had complications in the antenatal period or during labour. This group of babies had higher CA levels and were more acidaemic than fetuses after normal pregnancies and labour. There were stronger correlations between lactate and noradrenaline (NA) (R = 0.56, P < 0.001), adrenaline (A) (R = 0.41, P = 0.002) and dopamine (DA) (R = 0.42, P = 0.001) in cord artery blood, than previously reported for normal deliveries. Correlations between L/P ratio and CAs were also significant, although weaker. Multiple regression analysis, using cord artery lactate as the dependent variable, revealed significant correlations for pH (P = 0.01) and pyruvate (P < 0.001) but not for the CAs. The subgroups with high lactate (> 75th centile) had significantly higher NA (P = 0.007) and DA (P < 0.001) in cord artery and NA (P < 0.001) and A (P < 0.001) in cord vein blood, as compared with the subgroup who had lower lactate concentrations. We conclude that fetal hypoxia induces fetal CA production as well as anaerobic metabolism with lactate production. However, the adrenergic stimulation seems not to contribute significantly to the fetal lactate production.

Volume kinetics of Ringer's solution and dextran 3% during induction of spinal anaesthesia for caesarean section

PURPOSE

To study how the body handles fluid given intravenously during the onset of spinal anaesthesia in women scheduled for Caesarean section.

METHODS

The effect of spinal anaesthesia on the volume kinetics of a constant-rate infusion of 25 ml.kg-1 of Ringer's solution (n = 11) and 10 ml.kg-1 of dextran 3% 60 (n = 8) was studied before elective Caesarean section. Measurements of the blood haemoglobin concentration and urine excretion served as input variables in calculations of the size(s) of the body fluid spaces expanded by the infused fluid. The blood glucose level was also monitored.

RESULTS

When a one-volume kinetic model were fitted to the data, spinal anaesthesia reduced the size of the expanded body fluid space by 30% (Ringer's) and 58% (dextran) (P < 0.02) When a two-volume model was statistically justified, anaesthesia reduced the rate of fluid equilibration between the two expanded body fluid spaces by 47% and 19%, respectively (P < 0.04) The baseline volume for the primary (central) fluid space was smaller than the expected plasma volume; 1.5 l for Ringer's solution and 0.9 l for dextran. Only small changes in the blood glucose concentration were found.

CONCLUSION

The onset of spinal anaesthesia induces acute changes in the body's handling of infused fluid that can be described by volume kinetic analysis.

Intrapartum maternal glucose infusion reduces umbilical cord acidemia

OBJECTIVE

Our purpose was to compare the effects of intrapartum 5% glucose in the intravenous fluid on umbilical cord acid-base and glucose status after spontaneous vaginal delivery.

STUDY DESIGN

This was a prospective randomized clinical trial in which gravid women with low-risk pregnancies at term were randomized by computer to receive lactated Ringer's solution, either with 5% glucose or without, as the maintenance intravenous fluid during active labor. Antepartum and intrapartum factors that might influence fetal-neonatal glucose levels were recorded. Umbilical arterial cord blood was assessed for glucose level and acid-base status.

RESULTS

Of the 106 parturient patients who consented, 15 were excluded because of operative delivery (n = 8), preeclampsia (n = 2), shoulder dystocia (n = 1), intravenous fluid infusion duration of < 1 hour (n = 1), and cord blood data not available (n = 3). There were no statistical differences between the two groups regarding maternal age, parity, maternal weight at term, epidural placement, intravenous fluid duration, or gestational age. Infant birth weight, gender, Apgar scores, and incidence of meconium were not statistically different. Neonatal hypoglycemic episodes and intrapartum fetal heart rate tracing parameters were similar between groups. The difference between the umbilical artery pH values of those who were treated with lactated Ringer's solution with 5% glucose (n = 48) versus those treated with the solution without glucose (n = 43) approached significance, with a p value of 0.08 (mean +/- SD, 7.30 +/- 0.07 and 7.27 +/- 0.09, respectively). The PCO2 value of those treated with lactated Ringer's solution without glucose was higher (mean +/- SD, 50.6 +/- 12.9 mm Hg vs 44.8 +/- 9.9 mm Hg) (p = 0.02). Base excess (in milliequivalents per deciliter) and cord glucose (in milligrams per deciliter) levels, as well as the incidence of neonatal hypoglycemic episodes within the first 8 hours of life, were not statistically different. Despite failure of mean pH differences to achieve significance, the relative risk (0.22) for an umbilical arterial pH < or = 7.20 was significantly reduced (95% confidence interval 0.1 to 0.7) with lactated Ringer's solution containing 5% glucose. The relative risk (0.42) of having an umbilical artery cord blood PCO2 value > or = 55 mm Hg was also significantly lowered (95% confidence interval 0.19 to 0.93) when lactated Ringer's solution containing 5% glucose was used.

CONCLUSIONS

Intrapartum intravenous fluid consisting of lactated Ringer's solution containing 5% glucose reduces umbilical cord acidemia and hypercarbia but does not change cord levels of glucose or base excess. Lactated Ringer's solution containing 5% glucose may be a preferable solution than without glucose as an intravenous fluid during labor.

Fetal monitoring with lactate

Lactate is a metabolite that can safely and easily can be determined in fetal scalp blood using new microvolume (5-20 microliters) lactate meters. However, new lactate analysing methods need their own reference values. There are factors other than hypoxia that might increase fetal lactate levels, although this does not disqualify this parameter for intrapartum surveillance. Available data on fetal lactate determination give support that it can simplify FBS in labour and is likely to predict fetal tissue hypoxia at least as well as is pH determination. Prospective randomized studies are needed before the method can be introduced into clinical practice. As a predictor of neonatal outcome, lactate can substitute pH in routine assessment of cord artery blood at delivery.

Recommendations for the management of low risk obstetric patients

Specific interventional procedures have enjoyed widespread popularity in the United States in the routine management of low risk obstetric patients without the benefit of clinical studies attesting to their utility. A review of the literature was conducted to survey obstetric practice with regard to amniotomy, intravenous fluids, third stage administration of oxytocics, episiotomy and continuous fetal monitoring.