MORBIDLY OBESE PARTURIENT

1. MORBIDLY OBESE PARTURIENT Presenter –Dr Shwetha Moderator- Prof Arora www.anaesthesia.co.inanaesthesia.co.in@gmail.com

2. CONTENTS • Definition • Prevalence • Pathophysiological changes • Maternal and perinatal outcome • Anesthetic management • Post-operative care

3. OBESITY • A condition in which body fat is in excess beyond a point incompatible with physical and mental health and normal life expectancy • INDICES TO DEFINE OBESITY Index Definition Values ________________________________________ Broca index Ideal female weight Ht (cm) – 105 Overweight 20% > ideal Morbid obesity Ideal weight x 2 Body Mass Wt (kg) obese > 30 (Quetelet) index Ht (m)2 ______________________________________________ From Dewan DM, The obese parturient. In James FM, Wheeler AS, Dewan DM, editors. Obsteric Anesthesia: The Complicated Patient, 2nd ed. Philadelphia, FA Davis, 1988:468.

4. WHO CLASSIFICATION

5. Morbid Obesity • BMI > 40 kg.m-2 • BMI 35- 40 kg/m-2 in presence of significant co-morbid conditions that could be improved by weight loss • BMI > 55 kg.m-2 = Super-morbid obesity

6. TYPES OF OBESITY Android -truncal distribution of fat -high incidence of cardiovascular disorders Gynecoid -fat is distributed to thighs & buttocks -associated with pregnancy -not tightly linked to cardiovascular problems

7. Obesity in pregnancy The optimal definition is unclear • weight-to-height ratio • Pre-pregnant BMI ≥30 • wt of >90 kg/ >200 lb at any time during pregnancy • >20% increase in weight during pregnancy

8. Prevalence • In US >66% adults are overweight & 32% are obese • Increase in pre-partum obesity from 13% in 1993–94 to 22% in 2002–03 Obesity (Silver Spring) 2007; 15: 986–93 • In UK,33% overweight 23% obese • Women with BMI >30 increased from 12% in 1993 to 18.3% in 2002 Health Survey of England 2002

9. Indian scenario • Increasing trend towards obesity in Indian women from 10% in 1998-99 to 14.6% in 2005 Durgaprasad et al; IJA;2010 • Regional variation in obesity in females Punjab- 37.5% Kerala- 34% Goa-27%

10. Pathophysiological changes in obese pregnant patient • Obesity compounds most of the physiological changes in pregnancy

11. Airway Obesity and pregnancy each increase the chance of difficult airway • Obesity • Limited mouth opening • Limited neck movements • Narrowing of the pharyngeal opening • High mallampati grades • Increased anteroposterior diameter of the chest • Decreased chin-to-chest distance • Pregnancy • Edematous Mucous membrane • Breast enlargement

12. 33% incidence of difficult intubation Hood DD et al  Anesthesiology  1993; 79:1210-1218 • Difficult mask ventilation → gastric distention with air → increases the risk of regurgitation and aspiration • Impaired identification of the cricoid ring during rapid-sequence induction • Difficult cricothyrotomy/tracheostomy • Increased likelihood of unsuccessful transtracheal jet ventilation

13. Respiratorychanges

14. Vaughan RW. Pulmonary and cardiovascular derangements in the obese patient. In Brown BR, editor. Anesthesia and the Obese Patient. Philadelphia, FA Davis 1082:26.)

15. Obstructive Sleep Apnea • Women with obesity are more likely to have obstructive sleep apnea • Prevalence is unknown in pregnancy(Sleep disturbances and day time fatigue are normal at the end of pregnancy) • Women with BMI > 35, neck circumference >16 inches, symptoms of suspected airway obstruction during sleep should be screened by polysomnography and advised continuous positive airway pressure (CPAP) if required

16. PICKWICKIAN SYNDROME or Obesity Hypoventilation Syndrome • 8% of obese patients • Alveolar hypoventilation, somnolence and morbid obesity • Decreased sensitivity to arterial CO2 • ABG is useful to screen hypoxia, hypercarbia and acidosis • Echocardiogram should be done to evaluate cardiac function

17. ↑ Soft tissue mass of oropharynx Intermittent obstruction of airway during sleep Hypoxemia, hypercarbia Polycythemia, pulmonary hypertension and right ventricular failure

18. Cardiovascular changes

19. Gastrointestinal system ↑risk of aspiration of gastric contents & Mendelson’s syndrome • ↓LES tone which is already ↓in pregnancy • Hiatus hernia • 88% of obese, nonpregnant patients had a gastric pH of <2.5, and 86% had a gastric volume >25 mL Vaughan et al  Anesthesiology  1975; 43:686-689 • ↑incidence of diabetes causing delayed gastric emptying • Difficult or failed intubation

22. Pharmacokinetics and pharmacodynamics changes • Obesity affects the apparent volume of distribution (Vd) of anaesthetic drugs according to their lipid solubility • The loading dose of lipophilic opioids is based on total body weight • Drug clearance is usually normal or increased • Maintenance dosages should be cautiously reduced because of the higher sensitivity to their depressant effects

24. Minimum alveolar concentration ↓ • Increased body fat serves as a reservoir for inhalation and intravenous agents • sevofluraneand desflurane represent very flexible anaestheticdrugs with shortertime- to- extubation

25. Albumin binding of drugs unchanged • Levels of fatty acids, triglycerides, and a1-acid glycoprotein are increased • Pregnancy- volume of distribution is increased, albumin concentration decreased renal clearance is increased Net effect is unpredictable • Pseudocholinesterase levels are increased in pregnancy Bentley JB et al Anesthesiology  1982; 57:48-49.

26. Lower dose of local anaesthetic is required (less by 25%) when injected neuraxially • pregnancy induced hormone related changes in the action of spinal cord neurotransmitters • potentiationof the analgesic effect of the endogeneous analgesic systems • increased permeability of the neural sheath • decreased dilution by decreased volume of CSF • Increased cephalad spread of local anesthetics in obese patients due to relative trendelenburg position due to excess adipose tissue in buttocks

27. Effect of obesity on pregnancy Pregnant weight exceeding 250 lb increases the likelihood of complicating medical disease, obstetric complications, and operative delivery Obesity is associated with increased risk of • chronic hypertension( 28% vs 2%) • PIH (16% vs 10%) • diabetes mellitus- IDDM (2-8 fold) • Death- due to medical diseases(cardiovascular)

28. Effect on progress of labour ↑ risk of cesarean section , prolonged surgery • 2 fold ↑ in incidence of cesarean section among patients with a BMI of 40 kg/m2 • Abnormal presentation, fetal macrosomia, & prolonged labor are predisposing factors • Hypertension and diabetes prompt elective induction of labor, which may increase the risk of cesarean section • ↑ incidence of meconium-stained amniotic fluid, umbilical cord accidents & late fetal heart rate (FHR) decelerations

29. Perineal fat and intrapelvic fat deposits near the sigmoid colon and lateral pelvic sidewalls may alter the shape of the vaginal canal • Medicolegal considerations

30. Perinatal Outcome • Fetal macrosomia→ shoulder dystocia, birth trauma • Higher risk of late fetal death(tenfold increase in peri-natal mortality) • Increased risk of neural tube defects and other congenital malformations • Increased frequency of neonatal intensive care unit admissions

31. ANESTHETIC MANAGEMENT • Antenatal assessment • Labour analgesia • Ceasarean section -Epidural -Spinal -General Anesthesia -Local infiltration • Post-op care

32. Ante-natal Assessment Timing • Early 3rd trimester, or earlier depending on severity/ other co-morbidities Re-evaluate on admission for delivery • Perform the consultation / assessment • Develop anaesthesia plan • Communicate anaesthesia plan • Conduct the plan

33. General Strategy • Consultant anaesthetist should be involved as early as possible • Avoid GA if feasible • To increase safety of GA if needed • Advise any actions/referrals • Communication / Explanation

34. Ante-natal AnaestheticAssessment • Sensitive approach - establish rapport • History - Relevant anaesthesia records • Obstetric history and plans • Airway/ventilatory assessment • CVS and other co-morbidities • L spine • IV access • BP monitoring • pulse oximetry • ABG • Others

35. Analgesia for labour • Fetal macrosomia & shoulder dystocia→ more painful contractions and complicated labour • Effective pain relief during labour improve maternal respiratory function and attenuate sympathetically mediated cardiovascular responses • Analgesia using neuroaxial blockade has been shown to be the most effective 

36. Lumbar epidural analgesia ADVANTAGES • Pain relief with little motor block • Provides profound anesthesia for operative vaginal delivery • Does not affect the likelihood of vaginal delivery • Reduces oxygen consumption • Attenuates the increase in cardiac output that occurs during labor and delivery • May be extended for cesarean section if necessary

37. Douglas et al used a continuous epidural infusion of bupivacaine and fentanyl to provide analgesia in a morbidly obese parturient whose pregnancy was complicated by angina, insulin-dependent diabetes mellitus, hypertension, asthma, and benign intracranial hypertension

38. Limitations • Buckley et al reported a 20% incidence of failed epidural analgesia in morbidly obese patients one patient had inadequate block and they were unable to identify the epidural space in 10 patients • Increased depth of the epidural space • Require more attempts to identify the epidural space • Need for placement of a second or third catheter due to catheter displacement • Increased incidence of unilateral blockade

39. ultrasonographic guidance to facilitate identification of the epidural space

41. Benefits of ultra-sound in CNB • Identication of midline • Identification of the level • Identification of optimal space • Estimation of depth of epidural space • But there are limitations….. • Needs expertise • Often difficult to identify the shadow of spinal process in obese

42. Sitting position facilitates identification of midline • Distance from the skin to epidural space is less when the patient is sitting • Patient can guide identification of midline In cases of unintentional dural puncture, continuous spinal analgesia represents an alternative technique for providing labor analgesia

43. Combined Spinal Epidural Success depends on familiarity with technique Advantages • More versatile to titrate the block and dose • Faster onset compared to epidural alone • Useful for post operative analgesia and re-operative anaesthesia • Appearance of cerebrospinal fluid indirectly confirms correct epidural needle placement and increase the chance of functional epidural catheter Limitation • Potential for failed epidural analgesia after successful spinal analgesia

44. cesarean section • General anaesthesia with airway management problems has been the major reason of maternal mortality CEMACH 2003-05 • Regional anaesthesia preferably epidural should be opted unless contraindicated or difficult

45. Premedication • Aggressive pharmacologic anti-aspiration prophylaxis • 30 mL of 0.3 M solution of sodium citrate effectively increases gastric pH within 5 mins • H2-receptor antagonist and metoclopramide provide additional protection • Metoclopramide may be less effective in the presence of preexisting anticholinergic or opioid therapy

46. Positioning • Protuberant abdomen may shift remarkably when the patient is tilted toward the left • Patient must be secured to the operating table before she is tilted leftward • Tseuda et al reported that two obese patients experienced acute cardiovascular collapse after placement in the supine position

47. SPINAL ANESTHESIA Concerns • technical difficulties • potential for an exaggerated spread • Feasible in most morbidly obese parturients-spinal needle with extra length may be required • Blass successfully performed spinal anesthesia in 25 morbidly obese patients in whom standard epidural needles were of insufficient length to reach the epidural space

48. CSF volume in obese • Magnetic resonance imaging (MRI) has confirmed that obese patients have reduced CSF volume • Lower CSF volumes may increase the risk of a high spinal block • Large buttocks often present in obese patients place the vertebral column in a Trendelenburg position and may result in an exaggerated spread of anesthesia

49. Limitations • Higher incidence of hypotension as compared to other regional techniques • Prone for prolonged surgery • Duration of cesarean section exceeded 2 hrs in 55% of women who weighed more than 250 lb Johnson et al ObstetGynecol  1988; 72:91-97 • Intraoperative induction of general anesthesia is undesirable and perhaps hazardous

50. Continuous Spinal Anesthesia • Dural puncture can be intentional or unintentional • Catheter is introduced 2-3cm in subarachnoid space •  Final density and level are proportional to the dose in mgs, not the volume delivered  Advantages • Reliable • Can be used for analgesia as well as anaesthesia • Good control of anesthetic level & duration of block • Minimizes the risk of catastrophic loss of the airway