Interventions at caesarean section for reducing the risk of aspiration pneumonitis

The Effect of Various Pre-Cesarean Fasting Times on Maternal and Neonatal Outcomes

Background

Although it is currently recommended that patients avoid solid food for 6-8 h and liquid for 2 h before cesarean section, longer restrictions still apply in many centers. Since studies on the duration of fasting before cesarean section is scarce, we aimed to investigate the effect of different fasting times before cesarean section on maternal and neonatal complications.

Materials and methods

This descriptive study was performed on 405 candidates for cesarean section. These women were divided into five groups due to the length of time they did not consume clear liquid and solid food. Then, maternal and neonatal outcomes were compared using Kruskal-Wallis and Chi-square tests.

Results

The rate of nausea during surgery was lower in the groups who ate solid food between 2 and 8 h and clear liquid <2 h before surgery (P = 0.04). Also, abdominal distension in the first 6 h after surgery in the group that did not eat solid food for <6-8 h and clear liquid for <2 h was more than in the other groups (P < 0.05). The prevalence of hypoglycemia was significantly lower in women who ate solid food for <6 h and drank clear liquid for <2 h (P < 0.05).

Conclusion

Prolonged fasting time before cesarean section not only reduce complications but also may have undesirable consequences. The results of this study showed that it is better to use less strict measures in patients who are candidates for cesarean section and in patients with labor pains who are likely to have a cesarean section.

[Selection of the optimal anesthesia regimen for cesarean section]

Approximately one third of all children in Germany are delivered by cesarean section. Depending on the individual patient's condition and the situation, the anesthesiologist has to choose between a general or a regional anesthesia regimen. The decisive factor for the selection is the obstetric urgency (decision-delivery time) after ascertainment of the indications. Furthermore, the need for postoperative analgesia varies depending on the chosen anesthesia regimen.

Ultrasound your NPO: Effect of body mass index on gastric volume in term pregnant women - Retrospective case series

Introduction

A common belief has been that obese patients are prone to develop aspiration of gastric contents when general anesthesia is administered. We aimed to determine the correlation between antral cross-sectional area as a surrogate of gastric volume measured by gastric ultrasound, and body mass index (BMI) in term pregnant women scheduled for elective cesarean section.

Methods

A cross-sectional observational study was conducted on forty-two term pregnant patients scheduled for cesarean section. A preoperative qualitative and quantitative ultrasound assessment of the antral area was performed on the day of surgery. Gastric volume as a function of BMI was evaluated.

Results

A significant correlation was found between BMI and gastric antral area (p = 0.001), as well as with longitudinal diameter (p < 0.001). This correlation is independent of gravidity and parity.

Conclusion

BMI is an independent predictor of the antral cross-sectional area and gastric volume in term pregnant patients scheduled for cesarean section. Perioperative fasting guidelines in pregnancy should be adjusted in obese and morbidly obese pregnant women.

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Body mass index predicts gastric volume in term pregnant patients.

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The effect of body mass index on gastric volume is independent of gravidity and parity.

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Fasting guidelines in obstetrics should take into account body mass index.

Estimation of Gastric Volume Before Anesthesia in Term-Pregnant Women Undergoing Elective Cesarean Section, Compared With Non-pregnant or First-Trimester Women Undergoing Minor Gynecological Surgical Procedures

Background:

Traditionally, intubation of pregnant women has been performed using a rapid sequence induction. This is due to the classical concept that women with more than 18 weeks of pregnancy (mid-second trimester) are always considered to have an increased risk of aspiration due to a number of factors, regardless of the fasting duration. Rapid sequence induction is associated with a higher rate of adverse events.

Aims:

Our study aimed to illuminate the hypothesis that there is no difference in gastric volume between term-pregnant women and non-pregnant or first-trimester pregnant women who were undergoing minor gynecological surgical procedures. Accordingly, we measured gastric volume and content before anesthesia in term-pregnant women undergoing elective cesarean section, and to compare it with non-pregnant or first-trimester pregnant women who were undergoing minor gynecological surgical procedures.

Methods:

In this single-center prospective study, the gastric volume and content were assessed by abdominal ultrasound (AUS) just prior to the scheduled procedure. AUS was performed in the sagittal or para-sagittal plain in the upright position and the stomach content was estimated according to the antral circumferential area. Group 1 consisted of 50 term-pregnant women scheduled for cesarean section. Group 2 consisted of 45 non-pregnant or first-trimester pregnant women who were scheduled for minor gynecologic procedure.

Results:

Despite significant longer fasting time prior to the interventional procedure in the non-pregnant or first-trimester women group, there was no significant difference in gastric volume between term-pregnant and first-trimester pregnant women (3.2 ± 0.97 cm² vs 3.2 ± 0.79 cm²; P = .97). Gastric volume was small in the two groups.

Conclusion:

Fasting gastric volume before cesarean section in term-pregnant women is small and is not different than in non-pregnant or first-trimester women undergoing minor gynecologic procedures. Ultrasound estimation of gastric volume is a reliable and easy-to-perform technique which might help in decision-making regarding the airway management prior to induction of anesthesia in pregnant women.

Management of pregnant patients undergoing general surgical procedures

Pregnant patients have a 0.2% to 0.75% chance of developing a medical condition that requires a general surgical intervention during pregnancy. To safely and appropriately care for patients, surgeons must be cognizant of the maternal physiologic changes in pregnancy as well as of the unique risk to both mothers and fetuses of diagnostic modalities, anesthetic care, operative intervention, and postoperative management. Surgeons can be assured that, if these risks are understood and considered, operating during pregnancy, even in the abdomen, can be safely undertaken.

Interventions at caesarean section for reducing the risk of aspiration pneumonitis

BACKGROUND

Aspiration pneumonitis is a syndrome resulting from the inhalation of gastric contents. The incidence in obstetric anaesthesia has fallen, largely due to improved anaesthetic techniques and the increased use of regional anaesthesia at caesarean section. However, aspiration pneumonitis is still a cause of maternal morbidity and mortality, and it is important to use effective prophylaxis.

OBJECTIVES

To determine whether interventions given prior to caesarean section reduce the risk of aspiration pneumonitis in women with an uncomplicated pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 April 2013).

SELECTION CRITERIA

Randomised controlled trials were included. Quasi-randomised trials were excluded.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked. Fixed-effect meta-analysis was used to combine data where it was reasonable to assume that studies were estimating the same underlying treatment effect. If substantial clinical or statistical heterogeneity was detected, we used random-effects analysis to produce an overall summary.

MAIN RESULTS

Thirty-two studies were included in this review. However, only 22 studies, involving 2658 women, provided data for analysis. All the women in the included studies had a caesarean section under general anaesthesia. The studies covered a number of comparisons, but were mostly small and of unclear or poor quality.When compared with no treatment or placebo, there was a significant reduction in the risk of intragastric pH < 2.5 with antacids (risk ratio (RR) 0.17, 95% confidence interval (CI) 0.09 to 0.32, two studies, 108 women), H2 antagonists (RR 0.09, 95% CI 0.05 to 0.18, two studies, 170 women) and proton pump antagonists (RR 0.26, 95% CI 0.14 to 0.46, one study 80 women). H2 antagonists were associated with a reduced the risk of intragastric pH < 2.5 at intubation when compared with proton pump antagonists (RR 0.39, 95% CI 0.16 to 0.97, one study, 120 women), but compared with antacids the findings were unclear. The combined use of 'antacids plus H2 antagonists' was associated with a significant reduction in the risk of intragastric pH < 2.5 at intubation when compared with placebo (RR 0.02, 95% CI 0.00 to 0.15, one study, 89 women) or compared with antacids alone (RR 0.12, 95% CI 0.02 to 0.92, one study, 119 women).

AUTHORS' CONCLUSIONS

The quality of the evidence was poor, but the findings suggest that the combination of antacids plus H2 antagonists was more effective than no intervention, and superior to antacids alone in preventing low gastric pH. However, none of the studies assessed potential adverse effects or substantive clinical outcomes. These findings are relevant for all women undergoing caesarean section under general anaesthesia.

Restricting oral fluid and food intake during labour

BACKGROUND

Restricting fluids and foods during labour is common practice across many birth settings with some women only being allowed sips of water or ice chips. Restriction of oral intake may be unpleasant for some women, and may adversely influence their experience of labour.

OBJECTIVES

To determine the benefits and harms of oral fluid or food restriction during labour.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2013) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of restricting fluids and food for women in labour compared with women free to eat and drink.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction.

MAIN RESULTS

We identified 19 studies of which we included five, involving 3130 women. We excluded eight studies, one awaits classification and five are ongoing studies. All the included studies looked at women in active labour and at low risk of potentially requiring a general anaesthetic. One study looked at complete restriction versus giving women the freedom to eat and drink at will; two studies looked at water only versus giving women specific fluids and foods and two studies looked at water only versus giving women carbohydrate drinks.When comparing any restriction of fluids and food versus women given some nutrition in labour, the meta-analysis was dominated by one study undertaken in a highly medicalised environment. There were no statistically significant differences identified in: caesarean section (average risk ratio (RR) 0.89, 95% confidence interval (CI) 0.63 to 1.25, five studies, 3103 women), operative vaginal births (average RR 0.98, 95% CI 0.88 to 1.10, five studies, 3103 women) and Apgar scores less than seven at five minutes (average RR 1.43, 95% CI 0.77 to 2.68, four studies, 2902 infants), nor in any of the other outcomes assessed. Women's views were not assessed. The pooled data were insufficient to assess the incidence of Mendelson's syndrome, an extremely rare outcome. Other comparisons showed similar findings, except one study did report a significant increase in caesarean sections for women taking carbohydrate drinks in labour compared with water only, but these results should be interpreted with caution as the sample size was small.

AUTHORS' CONCLUSIONS

Since the evidence shows no benefits or harms, there is no justification for the restriction of fluids and food in labour for women at low risk of complications. No studies looked specifically at women at increased risk of complications, hence there is no evidence to support restrictions in this group of women. Conflicting evidence on carbohydrate solutions means further studies are needed and it is critical in any future studies to assess women's views.

Interventions for preventing nausea and vomiting in women undergoing regional anaesthesia for caesarean section

BACKGROUND

Nausea and vomiting are distressing symptoms which are experienced commonly during caesarean section under regional anaesthesia and can also occur in the period following the procedure. 

OBJECTIVES

To assess the efficacy of pharmacological and non-pharmacological interventions given prophylactically to prevent nausea and vomiting in women undergoing regional anaesthesia for caesarean section.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 February 2012) and reference lists of identified studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and excluded quasi-RCTs and cross-over studies.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked.  

MAIN RESULTS

Fifty-two studies met the inclusion criteria but only 41 studies, involving 5046 women, provided useable data for the review involving women having caesareans under regional anaesthesia. The majority of the studies involved women undergoing elective caesarean section. Only two studies included emergency surgery, however, they did not stratify data according to type of surgery. The studies covered numerous comparisons, but the majority of studies involved 5-HT(3) receptor antagonists, dopamine receptor antagonists, corticosteroids or acupressure. Studies were mainly small and of unclear quality.Three classes of intervention were found to be effective in at least three out of four of our primary outcomes (intraoperative nausea, intraoperative vomiting, postoperative nausea and postoperative vomiting). These interventions were 5-HT(3) antagonists, dopamine antagonists and sedatives. Other classes of intervention were effective for fewer than three of our primary outcomes.With 5-HT antagonists, we found a reduction in intraoperative nausea (average risk ratio (RR) 0.64, 95% confidence interval (CI) 0.46 to 0.88, eight studies, 720 women). There were also reductions in postoperative nausea (average RR 0.40, 95% CI 0.25 to 0.64, four studies, 405 women) and vomiting (average RR 0.50, 95% CI 0.32 to 0.77, five studies, 565 women). We did not detect a significant reduction in intraoperative vomiting (average RR 0.56, 95% CI 0.31 to 1.00, seven studies, 668 women).Dopamine antagonists demonstrated a reduction in intraoperative nausea (average RR 0.38, 95% CI 0.25 to 0.57, nine studies, 636 women) and intraoperative vomiting (average 0.39, 95% CI 0.24 to 0.64, eight studies, 536 women), with similar reductions in postoperative nausea (average RR 0.60, 95% CI 0.40 to 0.91, five studies, 412 women) and vomiting (average RR 0.57, 95% CI 0.36 to 0.91, six studies, 472 women). These differences were observed with both metoclopramide and droperidol.Sedatives (most commonly propofol) demonstrated a reduction in intraoperative nausea (average RR 0.71, 95% CI 0.52 to 0.96, four studies, 285 women) and intraoperative vomiting (average RR 0.42, 95% CI 0.26 to 0.68, four studies, 285 women), also with a reduction in postoperative nausea (average RR 0.25, 95% CI 0.09 to 0.71, two studies 145 women) and vomiting (average RR 0.09, 95% CI 0.03 to 0.28, two studies, 145 women).Acupressure was found to be effective for intraoperative nausea (average RR 0.59, 95% CI 0.38 to 0.90, six studies, 649 women) but not postoperative nausea (average RR 0.83, 95% CI 0.68 to 1.00, three studies, 429 women). Acupressure was not effective at reducing vomiting either intraoperatively (average RR 0.74, 95% CI 0.46 to 1.18, six studies, 649 women) or postoperatively (average RR 0.69, 95% CI 0.45 to 1.06, three studies, 429 women).Other effective intervention classes included corticosteroids, antihistamines, and anticholinergics.There were insufficient data to demonstrate any class of intervention was superior to another. There were no significant differences observed in the comparison of combined versus single interventions.Few studies assessed our secondary outcomes or the incidence of adverse effects. However, one study showed an increase in respiratory depression with sedation (midazolam) compared with dopamine antagonists.

AUTHORS' CONCLUSIONS

This review indicates that many different interventions have efficacy in preventing nausea and vomiting in women undergoing regional anaesthesia for caesarean section. There is little evidence that combinations of treatment are better than single agents.

Is anesthesia dangerous?

BACKGROUND

Recent years have seen a rise in overall anesthesia-related mortality.

METHOD

Selective review of the literature.

RESULTS

Anesthesia-related mortality has fallen from 6.4/10 000 in the 1940s to 0.4/100 000 at present, largely because of the introduction of safety standards and improved training. The current figure of 0.4/100 000 applies to patients without major systemic disease; mortality is higher among patients with severe accompanying illnesses, yet in this group, too, perioperative mortality can be reduced by appropriate anesthetic management. Moreover, the use of regional anesthesia can also improve the outcome of major surgery.

CONCLUSION

A recent increase in the percentage of older and multimorbid patients among persons undergoing surgery, along with the advent of newer types of operation that would have been unthinkable in the past, has led to an apparent rise in anesthesia-associated mortality, even though the quality of anesthesiological care is no worse now than in the past. On the contrary, in recent years, better anesthetic management has evidently played an important role in improving surgical outcomes.

Pneumonia complicating pregnancy

Community-acquired pneumonia (CAP) can affect pregnancy, posing risks to mother and fetus. CAP is the most common fatal nonobstetric infectious complication and a common cause of hospital readmission. Risk factors of pneumonia in pregnancy relate to anatomic and physiologic respiratory changes and immune changes. Aspiration can occur during labor, can cause life-threatening disease, and is more common in cesarean deliveries. Influenza pneumonia can cause severe disease, increasing the risk of preterm delivery, abortion, cesarean section, maternal respiratory failure, and death. CAP treatment requires considering antimicrobial appropriateness and safety, choosing therapy in line with guidelines, but considering maternal and fetal risk.