This ongoing column is authored by members of the International Society for the Perioperative Care of the Obese Patient (ISPCOP), an organization dedicated to the bariatric patient.
by Yigal Leykin, MD, MSc, and Alessandro Laudani, MD
Yigal Leykin and Alessandro Laudani are from the Department of Anesthesia, ICU, Pain Therapy, Santa Maria degli Angeli Medical Centre, Pordenone, Italy.
Funding: No funding was provided.
Disclosures: The authors do not have any conflicts on interest relevant to the content of this article.
Bariatric Times. 2013;10(1):28–29.
Obesity rates are steadily increasing among women of reproductive age, making it a common condition during pregnancy. Anesthesiologists are thus increasingly asked to care for morbidly obese parturients.
Maternal obesity is associated with increased morbidity, especially gestational diabetes and hypertensive disorders of pregnancy, as well as fetal complications, like macrosomia, stillbirth, and early neonatal death.[2,3] Women with obesity present a greater risk of having a post-term pregnancy and slower rates of cervical dilatation that often require induction of labor.
Moreover, parturients with obesity have a high rate of instrumental deliveries and Cesarean sections and an increased risk of anesthetic and postoperative complications (e.g., postpartum hemorrhage, wound and pulmonary infection).[3,5] The 2011 report of the Confidential Enquiry into Maternal and Child Health from the United Kingdom concluded that half of maternal deaths during the period between 2006 and 2008 occurred in women with overweight or obesity.
Physiological changes associated with pregnancy overlap with those already present in patients with obesity, leading to significant functional impairment and lower physiological reserve. In particular, the increase of cardiac output and oxygen consumption, the occurrence of aortocaval compression, and the reduction of functional residual capacity (FRC) are all exacerbated by obesity and can be a challenge for the anesthesiologist. Importantly, changes in the respiratory system make the obese parturient particularly prone to rapid desaturation, making an adequate pre-oxygenation before induction of general anesthesia even more important.
Obesity is also associated with significant changes in body composition and function that may alter the pharmacodynamics and pharmacokinetics of various drugs, leading to increased volume of distribution for lipophilic medications and lower volume of distribution for hydrophilic medications.
Pregnancy after bariatric surgery remains controversial, as there are both risks and benefits. Some studies have found that patients who conceived during the first postoperative year had comparable short-term perinatal outcome compared with patients who conceived after the first postoperative year.[11,12] Others authors recommend that women do not become pregnant within a certain period after undergoing bariatric surgery since surgery may induce a risk for malnutrition and pregnancy complications.[13,14] For instance, maternal complications, nutritional defects and intestinal obstruction are more frequently reported after Roux-en-Y gastric bypass (RYGB). In the case of malabsorption, nutritional supplementation is recommended.
The obstetric anesthetist must deal with technical and time-consuming challenges since parturients with obesity have a greater risk for difficult or failed intubation and a higher failure rate of regional anaesthesia.
Since most anesthesia-related maternal deaths are associated with airway management, general anesthesia should be avoided if at all possible. This is even more true for parturients with obesity. Obesity and pregnancy are associated with an increased risk of aspiration and Mendelson’s syndrome. Patients with obesity also have a higher incidence of hiatal hernia and elevated gastric pressure, which further increases the risk of pulmonary aspiration. Moreover, obesity and pregnancy each predispose the patient to difficult or failed tracheal intubation.
For these reasons, a complete airway assessment prior to all anesthesia and analgesia procedures on the labor floor is essential. Some advocate that all patients on the labor floor should undergo an airway examination on admission.
A rapid sequence anesthetic induction with succinylcholine is still the gold standard for general anesthesia for Cesarean section, unless a difficult intubation is expected. In that case, awake fiberoptic intubation is indicated, though it is time consuming and difficult to perform in urgent situations.
The Royal College of Obstetricians and Gynaecologists recommends that the obstetric anesthetist be informed when a woman with morbid obesity is admitted to the labor ward if delivery or operative intervention is anticipated. This allows time for the obstetric anesthetist to review documentation of the antenatal anaesthetic consultation, identify potential difficulties with regional and/or general anaesthesia, and alert senior colleagues if necessary. Early placement of an epidural may be advisable depending on the clinical scenario.
Although it remains controversial whether obesity influences the severity of labor pain, parturients with obesity are likely to have greater need for labor analgesia.5 Benefits of labor analgesia include improvement of maternal respiratory function and attenuation of stress-induced cardiovascular response. Neuraxial techniques remain the best methods for pain relief during labor. Moreover, a well-functioning epidural catheter placed in early labor can be useful in case of emergency Cesarean section to avoid the risks of a general anesthesia. Cesarean section neuraxial anesthesia is associated with a much lower risk than general anesthesia, and is therefore, considered first choice when no contraindications exist.
Regional techniques may be hard to perform due to difficulty in identifying anatomic landmarks. Ultrasound is increasingly used to identify the midline and the depth of the epidural space; however, it requires training in ultrasound visualization. Longer spinal or epidural needles may be required, although it is rare to encounter the epidural space at a depth greater than 80mm. The epidural catheter should be inserted at least 6cm into the epidural space to prevent displacement. Dose requirements for spinal or epidural anesthesia may be 20 to 25-percent less in parturients with obesity, since block height increases with increasing body mass index (BMI).
Surgery is more difficult in the patient with obesity and usually takes longer to perform. In addition, postoperative pain is higher. Anesthesiologists must be aware of this when choosing the anesthetic technique (e.g., a single-shot spinal may not provide long enough analgesia) and the postoperative pain treatment.
The management of a parturient with obesity requires adequate numbers of staff trained in manual handling techniques to facilitate patient transfer. It is vital to correctly position the patient on the operating table. A “ramped” position has been suggested, in which pillows or wedges are used to elevate the head and shoulders such that the external auditory meatus and sternal notch are aligned. In addition to optimizing access for direct laryngoscopy, elevation of the head improves the FRC, aiding pre-oxygenation if general anaesthesia should be required.
Thromboprophylaxis is recommended, preferably with low molecular weight heparin (LMWH), using an increased dose. Acceptable time after LMWH administration for block performance or catheter removal is 12 hours, while for next drug dose after block or catheter removal is four hours.
A multidisciplinary approach is warranted, bearing in mind the peculiar pathophysiological modifications and limitations imposed by pregnancy and concomitant obesity. Anticipating potential complications is critical in reducing maternal and perinatal morbidity and mortality. In parturients with obesity, the lack of an anesthetic plan can be disastrous (See Table 1 for a list of author recommendations for caring for the parturient with obesity).
Early preoperative assessment, epidural insertion, and replacement for failed regional anesthesia/analgesia along with preparation for general anesthesia (with possible difficult intubation) is advocated to decrease potential complications in the parturient with morbid obesity.
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