In 1946, Dr Curtis Mendelson suggested that aspiration during general anesthesia for delivery was avoidable by restricting oral intake during labor. This suggestion proved influential, and restriction of oral intake in labor became the norm. These limitations may contribute to fear and feelings of intimidation among parturients. Modern obstetrics, especially in the setting of advances in obstetric anesthesia, does not mirror the clinical landscape of Mendelson; hence, one is left to question if his findings remain relevant or if they should inform current recommendations. The use of general anesthesia at time of cesarean delivery has seen a remarkable decline with increased use of effective neuraxial analgesia as the standard of care in modern obstetric anesthesia. While the American College of Obstetricians and Gynecologists now endorses clear liquids during labor, current recommendations continue to suggest that solid food intake should be avoided. Recent evidence from a systematic review involving 3130 women in active labor suggests that oral intake should not be restricted in women at low risk of complications, given there were no identified benefits or harms of a liberal diet. Aspiration and other adverse maternal outcomes may be unrelated to oral intake in labor and as such, qualitative measures such as patient satisfaction should be paramount. It is time to reassess the impact of oral intake restriction during labor given the minimal risk of aspiration during labor in the setting of modern obstetric anesthesia practices.
In some settings, specifically birth centers, home births, and many European countries, oral intake during labor is encouraged for nourishment and comfort to help meet the demands of labor; however, in many birth settings this practice remains restricted. In 1946, Dr Curtis Mendelson suggested that aspiration during general anesthesia in obstetrics was avoidable with oral restriction in labor. As such, preventing Mendelson’s syndrome, the pneumonitis resulting from aspiration of gastric contents during general anesthesia, although rare, was the rationale for the oral intake restriction during labor that still exists today.
Obstetricians and anesthesiologists work in concert to ensure safe and optimal outcomes for both the mother and fetus regardless of mode of delivery. In the event that cesarean delivery requires general anesthesia, prevention of aspiration and elimination of airway-related adverse outcomes has to be balanced with the urgency of delivery. In 2013, the American Congress of Obstetricians and Gynecologists (ACOG) and American Society of Anesthesiologists (ASA) reaffirmed a joint practice guideline stating, “The oral intake of modest amounts of clear liquids may be allowed for uncomplicated laboring patients” but that “solid foods should be avoided in laboring patients.” They go on to state that “patients with risk factors for aspiration (eg, morbid obesity, diabetes, and difficult airway, or patients at increased risk for operative delivery) may require further restrictions of oral intake, determined on a case-by-case basis.”
Underlying risk factors exists that may put women at higher risk of aspiration events ( Table 1 ) during labor if general anesthesia becomes necessary ( Table 1 ). Notably, however, recommendations from professional organizations on the oral intake during labor remain quite varied ( Table 2 ). For example, in contrast to the joint ACOG/ASA recommendations, the World Health Organization (WHO) recommends that because the energy demands of labor are so great and because replenishment ensures maternal and fetal well-being, healthcare providers should not interfere with a woman’s desire for oral intake during labor.
|
| Organization | Recommendation | Strength of recommendation |
|---|---|---|
| American College of Nurse-Midwives | Self-determination regarding oral intake encouraged for women at low risk for aspiration. | Not provided |
| American Congress of Obstetricians and Gynecologists, American Society of Anesthesiologists Task Force on Obstetric Anesthesia | Clear liquids for women at low risk for aspiration. Small amounts of clear liquids up to 2 hours before anesthesia for women with no complications. | Not provided |
| World Health Organization (WHO) | Noninterference with desire for food or liquid intake without reason. | Not provided |
| Cochrane Review | Since evidence shows no benefits or harms, there is no justification for the restriction of fluids and food in labor for women at low risk of complications. | Not provided |
| Royal College of Obstetricians and Gynaecologists: NICE Clinical Guideline | Women may eat a light diet in established labor unless they have received opioids or they develop risk factors that make a general anesthesia more likely. | Not provided |
| Society of Obstetricians and Gynaecologists of Canada | A woman in active labor should be offered a light or liquid diet according to her preference. | Not provided |
| The Royal Australian and New Zealand College of Obstetricians and Gynaecologists | Women should be encouraged to only have clear fluids and light diet in the active phase of labor. | Not provided |
Table 1 provides a proposed list of patients at higher risk for aspiration which includes gastrointestinal and neurological disorders that may impair normal aspiration protective reflexes. Additionally, other obstetric conditions (maternal, fetal, anesthesia) that may place a woman at high risk for needing emergent cesarean delivery, possibly under general anesthesia, are included. These latter conditions are not absolute contraindications to oral intake in labor, and to some extent, those with a functioning epidural catheter for analgesia may actually be protective for aspiration in these circumstances as it may prevent the need for general anesthesia in the setting of an emergent cesarean delivery, thus altering their risk profile.
Fortunately, current practices in obstetric anesthesia have successfully reduced rates of general anesthesia and many of the known complications. Conversely, restriction of oral intake in labor may contribute to fear and feelings of intimidation among parturients. The recent systematic review that included 3130 women in active labor at low risk of requiring general anesthesia, noted no difference in maternal or neonatal outcomes with liberal versus restricted access to food and drinks. The goal of this commentary is to evaluate the evidence of restricting oral intake in the low-risk parturient and question the role of this common practice in modern obstetrics.
Historical perspective on restriction of oral intake in labor
In the landmark study by Mendelson, more than 44,000 pregnancies were studied at the New York Lying-In Hospital from 1932 to 1945 and the institutional experience with aspiration of stomach contents was reviewed. “Mendelson’s syndrome” was first described as aspiration of gastric contents resulting in a chemical pneumonitis characterized by hypoxia, cyanosis, dyspnea, fever, pulmonary edema, and death. His article was divided into a clinical report and an animal model.
In his clinical report, he noted 66 cases of aspiration (0.15%) and 2 deaths (0.0045%); however, both died of suffocation after aspiration of solids. Both deaths occurred among women who ate full meals at 6 and 8 hours before delivery, respectively. The other 64 non-fatal cases were almost all liquid aspirations and the actual aspiration “often escaped recognition” with recovery usually “complete with an afebrile and uncomplicated course.” These findings are the presumed basis for the modern restriction on intake of solid foods during labor.
Among Mendelson’s cohort, general anesthesia was not limited to women undergoing cesarean delivery. In fact, only 14 (21%) of the aspiration cases were among women delivered via cesarean. The majority of cases, 52 patients (79%) were either undergoing general anesthesia for spontaneous or operative vaginal deliveries. General anesthesia was used in all aspiration cases and consisted of a nonspecific mixture of gas, oxygen, and ether. Mask induction and maintenance was performed using opaque black rubber masks strapped on to the patient. Despite the initial severity of the illness, all patients had a rapid clinical recovery within 24 to 36 hours, with radiographic resolution within 4 to 7 days without the use of antimicrobial therapy. Based on these findings, Mendelson reached several conclusions: 1) Inhalation anesthesia without intubation for procedures in term pregnancies should be avoided; 2) opaque facemasks with head straps for inhalation anesthesia should be avoided; and 3) women should be discouraged from solid food during labor.
Commentaries at the time of Mendelson’s article from Paleul Flagg and James Miller, both American anesthesiologists, pointed to the need for designated anesthesiologists to obviate the risks that Mendelson had described. In contrast to Mendelson’s findings, Miller described over 26,000 deliveries at Hartford Hospital with no deaths secondary to asphyxia in a population cared for by a well-conducted anesthesiology service. This supported the idea that appropriately administered general anesthesia could reduce this risk of aspiration and asphyxia during labor.
Current perspectives of obstetric anesthesia regarding restriction of oral intake in labor
Modern obstetrics is markedly different from the landscape of Mendelson’s time. Aspiration in obstetrics has declined precipitously in the last thirty years, largely due to important advances in obstetric anesthesia. The risks associated with general anesthesia for cesarean delivery probably have been mitigated by the increased use of regional anesthesia, greater anesthesia care provider awareness of the potential for aspiration and difficult airway management in the parturient, advances in equipment for airway management, the broad utilization of pulse oximetry and capnography, and the adoption of difficult airway algorithms.
As a result of these advances, in many countries the policy of routine oral restriction for all parturients has been questioned. The triennial reports of the United Kingdom Confidential Enquiries into Maternal and Child Health indicate in spite of an increasingly flexible attitude toward oral intake during labor, the incidence of aspiration has actually declined in the past 20 years. In the 2003 to 2005 report, there were 6 anesthetic-related deaths among more than 2 million deliveries, and none were related to aspiration. Seventy-nine percent of clinicians in the Netherlands allow oral intake in labor and 32% of the 351 birth units in the United Kingdom allow food and drink. Although European guidelines continue to discourage women from intake of solid food during labor, they acknowledge the low incidence of aspiration in obstetrics and therefore state that “low risk women could consume low residue foods (biscuits, toasts, cereals) during labor.” Importantly, countries with a less restricted approach to oral intake during labor including the Netherlands have not witnessed a higher incidence of maternal complications attributed to aspiration.
The precipitous decline of cesarean deliveries that occur under general anesthesia is worth noting. In 2013 of 3.9 million births in the United States, the cesarean delivery rate was 32.7%, estimating the total number of cesarean deliveries at more than 1.2 million. The vast majority of cesarean deliveries are performed under regional anesthesia, evidenced by an anesthesia work force study from Bucklin et al. which found that overall rate of general anesthesia for cesarean delivery was between 3% to 5% at the largest facilities. This general anesthesia rate probably is lower than the rates in many birth settings in the United States and reflects data from before 2001. However, if one assumes a 4% incidence of general anesthesia at the time of cesarean delivery could be extrapolated to the number of cesarean deliveries performed in 2013, about 51,000 cesarean deliveries were performed under general anesthesia annually in the United States. In contrast, general anesthesia rates at cesarean delivery in 1981 were estimated to be 41% of the cesarean deliveries in facilities of all sizes.
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