PBLD2: The Morbidly Obese Patient

One-third of women aged 20-39 years old in the United States are classified as obese, with a BMI greater than 30kg/m2 (1). Various definitions of obesity exist in the literature and different criteria (pre-pregnancy weight vs. 10-14wk GA weight vs. term weight) have been used in studies which can make it more difficult to draw conclusions from the literature (2).

Classic definitions using pre-pregnancy BMI consider

• normal weight = 18.5-24.9kg/m2
• overweight = 25-29.9kg/m2
• obesity = >30kg/m2

The World Health Organization has further categorized obesity into three categories:

• Class 1 (BMI 30-34.9kg/m2)
• Class 2 (BMI 35-39.9kg/m2)
• Class 3 (BMI >40kg/m2)

Although not within this classification system, BMIs > 50kg/m2 are generally categorized as super morbid obesity (3).

Footnotes

1. Flegal KM, Carroll MD, Kit BK, Ogden CL. Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999-2010. JAMA : the journal of the American Medical Association. 2012;307(5):491-7.
2. Gunatilake RP, Perlow JH. Obesity and pregnancy: clinical management of the obese gravida. American journal of obstetrics and gynecology. 2011;204(2):106-19.
3. Obesity: preventing and managing the global epidemic. Report of a WHO consultation. World Health Organization technical report series. 2000;894:i-xii, 1-253.

In a population-based study by Weiss et al. which included over 16,000 patients, patients were categorized into three groups (4):

• BMI < 30kg/m2
• BMI = 30-34.9kg/m2 (obese)
• BMI > 35kg/m2 (morbidly obese)

Parturients with a BMI > 30kg/m2 were more likely than normal weight peers to develop:

1. Pre-eclampsia (OR = 1.6 in obese patients, 3.3 in morbidly obese)
2. Gestational hypertension (OR = 2.5 in obese patients, 3.2 in morbidly obese)
3. Gestational diabetes (OR = 2.6 in obese patients, 4.0 in morbidly obese)
4. Fetal birth weights over 4000grams (risk factor for shoulder dystocia)
5. Cesarean Delivery

In addition, maternal obesity is also a risk factor anesthesia-related maternal mortality and complications from cardiovascular disease and thromboembolism (5). Finally, obese patients are more likely to have either sleep disordered breathing or obstructive sleep apnea.

Fetal complications of obese mothers include recurrent first trimester losses, stillbirth (especially with comorbidity of GDM), congenital malformations (including neural tube and genitourinary defects), macrosomia, neonatal hypoglycemia, shoulder dystocia, and large for gestational age (6-8).

In addition, obese women may have longer labors compared to non-obese peers. The first stage of labor may be prolonged, but increasing body mass was not associated with increased duration for the second stage of labor(9-11).

Footnotes

4. Weiss JL, Malone FD, Emig D, Ball RH, Nyberg DA, Comstock CH, et al. Obesity, obstetric complications and cesarean delivery rate–a population-based screening study. American journal of obstetrics and gynecology. 2004;190(4):1091-7.
5. Mhyre JM, Riesner MN, Polley LS, Naughton NN. A series of anesthesia-related maternal deaths in Michigan, 1985-2003. Anesthesiology. 2007;106(6):1096-104.
6. ACOG Committee opinion no. 549: obesity in pregnancy. Obstetrics and gynecology. 2013;121(1):213-7.
7. Macumber I, Schwartz S, Leca N. Maternal obesity is associated with congenital anomalies of the kidney and urinary tract in offspring. Pediatric Nephrology. 2016:1-8.
8. Huang HY, Chen HL, Feng LP. Maternal obesity and the risk of neural tube defects in offspring: A meta-analysis. Obesity research & clinical practice. 2016.
9. Robinson BK, Mapp DC, Bloom SL, Rouse DJ, Spong CY, Varner MW, et al. Increasing maternal body mass index and characteristics of the second stage of labor. Obstetrics and gynecology. 2011;118(6):1309-13.
10. Carlhall S, Kallen K, Blomberg M. Maternal body mass index and duration of labor. European journal of obstetrics, gynecology, and reproductive biology. 2013;171(1):49-53.
11. Tonidandel A, Booth J, D’Angelo R, Harris L, Tonidandel S. Anesthetic and obstetric outcomes in morbidly obese parturients: a 20-year follow-up retrospective cohort study. Int J Obstet Anesth. 2014;23(4):357-64.

1. Maternal Vitals
2. FHTs
3. Airway Exam
4. Fetal Presentation
5. Anesthetic History (including previous intubation)
6. Obstetric history
7. Medical history (including allergies)
8. Pre-eclampsia labs (platelets, LFTs)
9. IV access
10. Blood Glucose Level

The American Society of Anesthesiologists and the American College of Obstetricians and Gynecologists both recommend preoperative anesthetic assessment of morbidly obese patients prior to their delivery for anesthetic planning. Unfortunately, this patient did not receive prenatal care (12, 13).

Footnotes

12. ACOG Practice Bulletin. Clinical Management Guidelines for Obstetrician-Gynecologists: number 41, December 2002. Obstetrics and gynecology. 2002;100(6):1389-402.
13. Practice Guidelines for Obstetric Anesthesia: An Updated Report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia and the Society for Obstetric Anesthesia and Perinatology. Anesthesiology. 2016;124(2):270-300.

Fetuses of diabetic mothers have significantly increased risk of death and morbidity. These risks may be due to prolonged exposure to intrapartum hyperglycemia, hyperinsulinemia and hypoxia-ischemia(14). Our patient did not receive prenatal care and her fetus may be at risk for morbidity.

Fetuses of diabetic mothers have an increased risk of: (14)

1. Stillbirth
2. Death within the first week of life
3. Congenital abnormalities including:
   • Cardiac (VSD and hypertrophic cardiomyopathy)
   • Neural tube defects
   • Anomalies of the limbs
   • Connective tissue defects
4. Neonatal polycythemia due to insulin-induced glucose uptake– (which can lead to neonatal jaundice as red cells are lysed as well as hyperviscosity syndrome)
5. Neonatal hypoglycemia (neonate will have an increased production of insulin as well as decreased hepatic glucose production and lipolysis)
6. Large for Gestational Age and Macrosomia
7. Preterm Delivery
8. Intrauterine growth restriction
9. Hypocalcemia and hypomagnesemia
10. Birth trauma (shoulder dystocia, head trauma, brachial plexus injury and fractured clavicle)

Footnote

14. Hawdon JM. Babies born after diabetes in pregnancy: what are the short- and long-term risks and how can we minimise them? Best practice & research Clinical obstetrics & gynaecology. 2011;25(1):91-104.

According to the 2013 practice bulletin from The American College of Obstetrics and Gynecology (ACOG), macrosomia and shoulder dystocia are more common for a given fetal weight in patients with gestational diabetes. Therefore, the ACOG recommends providing patients with gestational diabetes and an estimated fetal weight of greater than 4500gm an option of scheduled cesarean delivery (15).   For patients without gestational diabetes, a scheduled cesarean delivery can be offered if the estimated fetal weight is greater than 5000gm.

Footnote

15. Practice Bulletin No. 137: Gestational diabetes mellitus. Obstetrics and gynecology. 2013;122(2 Pt 1):406-16.

1. Airway (Mallampati classification, thyromental distance, cervical range of motion, mouth opening, circumference of neck, ability to prognathate)
2. Back examination
3. Cardiac exam
4. Lung exam
5. Edema in lower extremities
6. IV check (what gauge and flow)

Footnotes

16. Ellinas EH, Eastwood DC, Patel SN, Maitra-D’Cruze AM, Ebert TJ. The effect of obesity on neuraxial technique difficulty in pregnant patients: a prospective, observational study. Anesthesia and analgesia. 2009;109(4):1225-31.
17. Whitty RJ, Maxwell CV, Carvalho JC. Complications of neuraxial anesthesia in an extreme morbidly obese patient for Cesarean section. Int J Obstet Anesth. 2007;16(2):139-44.

Ellinas et al.  performed a prospective study of  neuraxial placement  and found that obesity by itself was not predictive of difficult epidural placement. The inability to palpate landmarks and decreased ability of the patient to flex her back were predictive of difficulty in placement (16).

Footnote

16. Ellinas EH, Eastwood DC, Patel SN, Maitra-D’Cruze AM, Ebert TJ. The effect of obesity on neuraxial technique difficulty in pregnant patients: a prospective, observational study. Anesthesia and analgesia. 2009;109(4):1225-31.

According to the literature, morbidly obese patients can have the following problems when neuraxial anesthesia is performed (17).

Difficulties

1. More difficulty determining midline or palpating landmarks (require more passes and longer placement times)
2. Subcutaneous fat pockets can produce “false loss”
3. May require longer Tuohy needle or spinal needle due to depth of epidural space (11-15cm needles)
4. Replacement rate may be higher due to catheter migration due to excess movement of skin and subcutaneous tissue
5. Increased epidural failure rate
6. More difficult to position the patient due to habitus
7. Sitting position for epidural placement may increase difficulty of externally monitoring fetal heart rate

Complications

1. Increased risk of accidental dural puncture
2. Increased risk of accidental epidural venous puncture

In order to set proper expectations with patients and be realistic, it is necessary to discuss how her obesity puts her at increased risk for complications and may require extra monitoring. It should be explained that early epidural placement is recommended as it may take longer to achieve and she and her baby may be at higher risk of complication if general anesthesia with endotracheal intubation is necessary (18).

Footnotes

17. Whitty RJ, Maxwell CV, Carvalho JC. Complications of neuraxial anesthesia in an extreme morbidly obese patient for Cesarean section. Int J Obstet Anesth. 2007;16(2):139-44.
18. Ring LE. The anesthetic approach to operative delivery of the extremely obese parturient. Seminars in perinatology. 2014;38(6):341-8.

1. OR bed that accommodates bariatric patients
2. Longer spinal or epidural needle
3. Advanced airway equipment
4. Positioning ramp or blankets
5. Large Blood Pressure cuffs
6. Ultrasound for neuraxial placement or IV access
7. Arterial line if unable to get accurate noninvasive BP readings

There are many factors that make the pregnant airway more challenging (19, 20).

1. Increased weight gain during pregnancy
2. Increased anterior-posterior diameter of chest due to progesterone relaxation of the intercostal ligaments – results in misalignment of the oral, pharyngeal and tracheal axes
3. Increased oxygen consumption lead to more rapid oxygen desaturations
4. Increased breast mass – may impede placement of laryngoscope (necessitating use of short handle laryngoscope)
5. Edema of the upper airway due to pregnancy– narrowing upper airway
6. More friable tissues and blood vessels due to progesterone influence
7. Progressive swelling during labor (21)

In addition, her morbid obesity increases her likelihood of undiagnosed obstructive sleep apnea which may make emergency mask ventilation as well as intubation more difficult.

According to the 2007 ASA Practice Guidelines for Obstetric Anesthesia, “The decision to use a particular anesthetic technique for cesarean delivery should be individualized, based on several factors. These include anesthetic, obstetric or fetal risk factors (e.g. elective vs. emergency), the preferences of the patient and the judgment of the anesthesiologist.” Pg 850(22) In this case the fetus is demonstrating indicators of placental ischemia and the patient no longer wants to allow the provider to attempt neuraxial anesthesia. Therefore, the obstetric anesthesiologists needs to adapt their plan to include general anesthesia.

Historically, general anesthesia has been considered to be much more dangerous than regional anesthesia. Recent closed claims comparing anesthetic complications of regional versus general anesthesia demonstrated that maternal mortality attributed to general anesthesia has decreased over time. Data from maternal mortalities during 1991-2002 demonstrated that overall 6.5 deaths per million were reported for general anesthesia cases and 3.8 deaths per million for regional anesthesia which is significantly improved from previous reports(23). This decline in deaths due to general anesthesia may reflect increased provider skill in performing general anesthesia for cesarean deliveries, or our proactive behaviors to avoid general anesthesia in high-risk patients. Overall, general anesthesia is relatively safe for the parturient. Historically, failed intubations in obstetric patients were reported to occur in 1:280 cases which is 8 times higher than non-pregnant surgical peers(24). Recent data from the Serious Complication Repository (SCORE) Project of the Society for Obstetric Anesthesia and Perinatology reported the incidence of failed intubation to be 1:533 with no reported gastric aspirations or hypoxic arrests during intubation(25). This may reflect recent airway device advances or again anticipatory practices to avoid general anesthesia for select patients.

In a review of anesthesia-related 1985-2003 maternal deaths in Michigan, Mhyre et al. demonstrated that maternal deaths in the peripartum period were more associated with airway obstruction and hypoventilation in obese patients following extubation and general anesthesia emergence rather than during intubation. This may indicate that post-operative monitoring of immediately postpartum patients who received general anesthesia is an important part of safe care (5).

Footnotes

19. Soens MA, Birnbach DJ, Ranasinghe JS, van Zundert A. Obstetric anesthesia for the obese and morbidly obese patient: an ounce of prevention is worth more than a pound of treatment. Acta anaesthesiologica Scandinavica. 2008;52(1):6-19.
20. Scott-Brown S, Russell R. Video laryngoscopes and the obstetric airway. Int J Obstet Anesth. 2015.
21. Kodali BS, Chandrasekhar S, Bulich LN, Topulos GP, Datta S. Airway changes during labor and delivery. Anesthesiology. 2008;108(3):357-62.
22. Practice guidelines for obstetric anesthesia: an updated report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Anesthesiology. 2007;106(4):843-63.
23. Hawkins JL, Chang J, Palmer SK, Gibbs CP, Callaghan WM. Anesthesia-related maternal mortality in the United States: 1979-2002. Obstetrics and gynecology. 2011;117(1):69-74.
24. Lyons G. Failed intubation. Six years’ experience in a teaching maternity unit. Anaesthesia. 1985;40(8):759-62.
25. D’Angelo R, Smiley RM, Riley ET, Segal S. Serious complications related to obstetric anesthesia: the serious complication repository project of the Society for Obstetric Anesthesia and Perinatology. Anesthesiology. 2014;120(6):1505-12.

1. Obesity has been associated with increasing difficulty with laryngoscopy
2. Obesity like pregnancy, decreases the overall FRC (both RV and ERV are decreased) and therefore, the patient will have less oxygen reserve than non-obese peers due to the upward pressure on the diaphragm due to the panniculus
3. Increasing tissue mass increases oxygen consumption, which will result in faster desaturation with apnea
4. Arterial blood gas demonstrates more hypoxemia in obese patients when compared to non-obese
5. Obesity is associated with OSA – may result in difficult mask ventilation if necessary

Although obesity has been associated with more difficult intubation, the current risk of failed intubation with the availability of advance airway devices is uncertain and requires further study. A prospective observational study by Bamgbade et al. failed to demonstrate an association between patient BMI and laryngoscopy grade although this was not the primary outcome of this study (26). Emerging evidence suggests that videolaryngoscopes may have a role in obstetric intubations and improve outcomes (20).

Footnotes

26. Bamgbade OA, Khalaf WM, Ajai O, Sharma R, Chidambaram V, Madhavan G. Obstetric anaesthesia outcome in obese and non-obese parturients undergoing caesarean delivery: an observational study. Int J Obstet Anesth. 2009;18(3):221-5.

The use of prophylactic antibiotics for cesarean delivery is well established and should be administered prior to skin incision compared to after cord-clamping (27). For cefazolin, the target tissue levels for gram positive cocci is greater than 1mcg/gm tissue and 4mcg/gm tissue for gram negative rod prophylaxis. The pharmacokinetics of antibiotics may differ in pregnant women due to physiological changes including an increase in GFR, an increased volume of distribution and a decrease in plasma proteins (28). Elkomy et al. demonstrated that cefazolin clearance increases 74% during pregnancy and cefazolin is rapidly transferred across the placenta (29). This study examining the pharmacokinetics of cefazolin administration in women undergoing scheduled cesarean delivery and their neonates found that a 2gm administration of cefazolin administered within an hour of surgery produces effective blood concentrations in both maternal and cord blood.

Current best practices for antibiotic dosing for obese parturients is controversial and no current guidelines exist although several studies have indicated that obese patients may require higher doses of antibiotics (30). Stitely et al. examined plasma and tissue cefazolin concentrations in obese patients (BMI >35kg/m2) and found that a prophylactic doses of 2gm of cefazolin was adequate to produce recommended target tissue levels (31). However, Pevzner et al. demonstrated that 2gms cefazolin surgical prophylaxis did not reliably produce therapeutic tissue concentrations in extremely obese patients (BMI > 40kg/m2) (30). Further studies may be needed to elucidate antibiotic regiments for the extremely obese parturient.

Footnotes

27. Sun J, Ding M, Liu J, Li Y, Sun X, Liu T, et al. Prophylactic administration of cefazolin prior to skin incision versus antibiotics at cord clamping in preventing postcesarean infectious morbidity: a systematic review and meta-analysis of randomized controlled trials. Gynecologic and obstetric investigation. 2013;75(3):175-8.
28. ACOG Practice Bulletin No. 120: Use of prophylactic antibiotics in labor and delivery. Obstetrics and gynecology. 2011;117(6):1472-83.
29. Elkomy MH, Sultan P, Drover DR, Epshtein E, Galinkin JL, Carvalho B. Pharmacokinetics of prophylactic cefazolin in parturients undergoing cesarean delivery. Antimicrobial agents and chemotherapy. 2014;58(6):3504-13.
30. Pevzner L, Swank M, Krepel C, Wing DA, Chan K, Edmiston CE, Jr. Effects of maternal obesity on tissue concentrations of prophylactic cefazolin during cesarean delivery. Obstetrics and gynecology. 2011;117(4):877-82.

Wound infection following cesarean delivery is common and may be more common in obese women(32). In addition, the combination of obesity and diabetes (either gestational or pregestational) may significantly increase the risk of developing wound infections and wound dehiscence(33). The skin thickness of the wound also seems to play a role in the development of infection, with skin thickness >3cm being associated with higher infection rates. In addition, suture closure of wounds reduces the rate of wound separation and wound morbidity compared to skin closure with staples(34). Neither the administration of high concentrations of supplemental oxygen nor the placement of prophylactic surgical drains has not been shown to reduce rates of infection or wound morbidity. The type of incision (vertical vs. transverse or supraumbilical vs infraumbilical) has not been definitively been shown to contribute to the development of wound infections.

Footnotes

32. Tipton AM, Cohen SA, Chelmow D. Wound infection in the obese pregnant woman. Seminars in perinatology. 2011;35(6):345-9.
33. Schneid-Kofman N, Sheiner E, Levy A, Holcberg G. Risk factors for wound infection following cesarean deliveries. International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics. 2005;90(1):10-5.
34. Mackeen AD, Schuster M, Berghella V. Suture versus staples for skin closure after cesarean: a metaanalysis. American journal of obstetrics and gynecology. 2014.

Conclusion

The patient undergoes an uneventful general anesthetic for her cesarean delivery. She is extubated and taken to the recovery room. Her recovery is uncomplicated and she is discharged on postoperative day 3.

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