1. MORBIDLY OBESE PARTURIENT
Presenter –Dr Shwetha
Moderator- Prof Arora

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

3. OBESITY INDICES TO DEFINE OBESITY Index Definition Values
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 Classification Body mass index (kg/m2)
Associated health risks
Underweight
<18.5
Low
Normal range
18.5–24.9
Average
Overweight
>25.0
  Preobese
25.0–29.9
Increased
  Obese class I
30.0–34.9
Moderately increased
  Obese class II
35.0–39.9
Severely increased
  Obese class III
>40
Very severely

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 Obesity (Silver Spring) 2007; 15: 986–93
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 to 18.3% in 2002
Health Survey of England 2002

9. Indian scenario
Increasing trend towards obesity in Indian women from 10% in 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:
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. Respiratory changes

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:
↑ incidence of diabetes causing delayed gastric emptying
Difficult or failed intubation

20. SYSTEM
PATHOLOGY
Respiratory
Obstructive sleep apnea, obesity-hypoventilation syndrome, asthma, pulmonary hypertension
Cardiovascular
Dysrhythmias, atherosclerosis, cardiac failure, coronary artery disease, peripheral vascular disease, sudden cardiac death, systemic hypertension, thromboembolism, varicose veins
Gastrointestinal
Colon cancer, gallbladder disease, gastroesophageal reflux disease, hernias, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis
Endocrine/metabolic
Diabetes mellitus, dyslipidemia, hyperinsulinemia, hypothyroidism, insulin resistance, metabolic syndrome
Genitourinary
End-stage renal disease, macrosomia, menorrhagia, preeclampsia and eclampsia, prostate cancer, urinary incontinence

21. Neurologic
Carpal tunnel syndrome, pseudotumor cerebri, stroke
Hematology
Hypercoagulability, polycythemia
Musculoskeletal
Acanthosis nigricans, gout, osteoarthritis, rheumatoid arthritis
Psychology/psychiatry
Depression, reduced self-esteem, social stigma

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
sevoflurane and desflurane represent very flexible anaesthetic drugs 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
potentiation of 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 Anaesthetic Assessment
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
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

51. Limitations
Risk of introducing air into the spinal space which causes pneumoencephalus headache 
Incidence of infection is higher with this technique compared to other regional techniques
Incidence of post dural puncture headache in obese parturients is lower

52. EPIDURAL ANESTHESIA Advantages Catheter can be placed early in labor
Can titrate the dose of local anesthetic agent
Decreased incidence of hypotension
Decreased potential for excess motor blockade
Facilitates postoperative analgesia
Decrease the risk of thromboembolic complications
Limitations
High failure rate (25%)
Difficulty blocking the sacral roots, resulting in visceral pain upon stimulation of the bladder

53. obesity affects the spread of epidural anesthesia
Height of the block was proportional to BMI and weight
Sitting position decrease cephalad spread of anesthesia in obese but not in lean patients
Incremental injection of local anesthetic most likely lessens the effect of obesity on the spread of epidural anesthesia

54. GENERAL ANESTHESIA Difficult tracheal intubation
H/O previous successful intubation does not guarantee the same result during subsequent procedure
Need for experienced and additional hands
The primary anesthetist fatigues rapidly while attempting mask ventilation

55. Equipment for Difficult Airway Management
Rigid laryngoscope blades of alternate design & size
Endotracheal tubes of assorted sizes.   
Endotracheal tube guides eg semirigid stylets, ventilating tube changer, light wands, and forceps
Laryngeal mask airways(LMA-Fastrach,ProSeal)
Fiberoptic intubation equipment
Retrograde intubation equipment
At least one device suitable for emergency nonsurgical airway ventilation egCombitube, hollow jet ventilation stylet, & transtracheal jet ventilator
Equipment suitable for emergency surgical airway access (e.g cricothyrotomy)
An exhaled CO2 detector
Rigid ventilating bronchoscope

56. Use of specialised pillows, ramp (horizontal alignment is achieved between the external auditory meatus and the sternal notch) improves the laryngeal view

57. Awake intubation
Catecholamine release & blood pressure elevation may exacerbate existing hypertension and adversely affect uterine blood flow
Some patients may require urgent administration of general anesthesia
Rapid-sequence induction
Should be done only in unanticipated difficult airway

58. Preoxygenation 8 vital capacity breaths of 100% oxygen
Pre-oxygenation achieved by eight vital capacity breaths within 60 s at an oxygen flow of 10 liters/min not only results in a higher partial pressure of arterial oxygen (PaO2) ,but also in a slower hemoglobin desaturation when compared with the four deep breaths technique
Baraka AS et al Anesthesiology 1999; 91: 612–6

60. Anesthetic drugs
Choice of intravenous agent is relatively unimportant in the absence of complicating medical disease
No study has specifically evaluated the use of ketamine
Thiopental <4 mg/kg may increase the risk of maternal hypertension, and decreased uterine blood flow during light anesthesia

61. Succinylcholine remains the muscle relaxant of choice for rapid-sequence induction
Cesarean section is technically difficult Adequate muscle relaxation is essential
Normal response to non depolarizing muscle relaxants

62. High concentrations of a volatile halogenated agent increase the likelihood of neonatal depression, uterine atony, and maternal blood loss
Low concentration of volatile agent increases the risk of maternal awareness, catecholamine release, hypertension, and decreased uterine blood flow

63. Administration of general anesthesia,supine and Trendelenburg positions may further decrease the FRC and increase the likelihood of intraoperative hypoxemia
Techniques that may improve intraoperative oxygenation
Increasing FiO2
large tidal volume
PEEP
elevation of the panniculus
PEEP increases maternal PaO2, but it may decrease cardiac output and oxygen delivery

64. Avoid airway obstruction during induction emergence from anesthesia
Extubation must be done when awake in left lateral position or semi upright position

65. The Bullard Laryngoscope for Emergency Airway Management in a Morbidly Obese Parturient Aaron I. Cohn, MD et al
Morbidly obese, 240 kg, 160 cm, 31-yr-old female presented for cesarean section due to fetal distress
Mallampati class IV airway, verified by two observers, and a thyromental distance of two finger-breadths
An adult Bullard laryngoscope with blade extender was inserted in the oropharynx.Vocal cords were easily visualized.
Glottic visualization was subsequently attempted under general anesthesia using a Macintosh 4 blade; however, only a grade III laryngoscopic view by the Cormack and Lehane classification could be obtained

66. Tracheal Intubation Using the Airtraq in two Morbid Obese Patients undergoing emergency Cesarean Delivery
Gilles Dhonneur, M.D et al
Direct laryngoscopy performed with a Macintosh metal blade showed Cormack grade 3 and 4, and tracheal insertion of a gum elastic bougie failed in both patients
Three minutes after loss of consciousness, the Airtraq equipped with a video camera inserted into the pharynx provided an entire glottis view and video-endoscopy of the tube entering the trachea

67. Pro-seal LMA has been used successfully as a rescue ventilation device following failed obstetric intubation
 Awan R, Nolan JP et al Br J Anaesth 2004;92:144-6
Case report of use of ProSeal laryngeal mask airway in failed intubation and postoperative respiratory support in an obese obstetric patient
Keller C, Brimacombe J et al Anesth Analg 2004;98:

68. 25-yr-old primigravida (BMI 49) at term pregnancy in labour
Successful delivery in a morbidly obese patient after failed intubation and regional technique doi: /bja/aem325
25-yr-old primigravida (BMI 49) at term pregnancy in labour
Caesarean section- performed with local anaesthetic infiltration and ‘Entonox’ after failed intubation and regional
Used oxygen 50% ;nitrous oxide 50% & 40 ml of plain bupivacaine 0.5% was injected into skin and s.c. tissue

69. Post-operative complications
Infections endometritis
-urinary tract infections
-wound infection
Respiratory -atelectasis
-pneumonia
-respiratory depression
-tracheal reintubation
-sleep apnea
Cardiovascular- cardiac arrest
-DVT
-pulmonary embolism
Nerve injuries

70. Postoperative Analgesia
Multimodal analgesia
NSAIDS
OPIOIDS
Intramuscular opioid-variable, unpredictable absorption of the drug
Intravenous-opioid more consistent effect
risk of respiratory depression
Intravenous sufentanil-
eliminated slowly
reduction in the maintenance dose

71. The Use of Remifentanil in Obstetrics- David Hill et al
Department of Anaesthesia, Ulster Hospital, Belfast UK
Remifentanil is most suitable for systemic opioid for use in obstetrics
onset and offset are rapid
analgesia is consistently high
Maternal oxygen desaturation limits the dose and suitable monitoring during use is advised
successful in blunting responses to airway manipulation and providing hemodynamic stability in high-risk women
Neonatal effects when used in labor are minimal with an infusion dose < 0.1 μg/kg/min

72. Infiltrative analgesia at the end of surgery
Thoracic epidural anesthesia ↓oxygen consumption & left ventricular stroke work
Spinal opioids can provide post operative analgesia but respiratory monitoring is essential
Epidural morphine results in earlier ambulation, fewer pulmonary complications, and shorter hospitalization when compared with im morphine in morbidly obese patients who had undergone abdominal surgery
Rawal et al anae anal;1984

73. Postoperative care Monitored or step down bed
Semi-recumbent or reverse trendelenberg position
Antibiotic prophylaxis
Anticoagulation soon after surgery with LMWH or unfractionated heparin.Dosing is based on actual body wt
Adequate postoperative analgesia to promote early ambulation
Catheters can be removed 10–12 hrs after the last dose of low molecular weight heparin (LMWH) and 4 hrs before the next dose

74. Increased incidence of postoperative pulmonary complications including hypoxemia, atelectasis and pneumonia
Preoperative pulmonary function may be the best predictor of postoperative pulmonary complications
Monitoring for hypoxia and hypoventilation
CPAP mask for OSA

75. Summary An ounce of prevention is worth more than a pound of treatment
Consultant based multidisciplinary approach
Early anaesthetic assessment
Prophylactic epidural block, ensuring its effectiveness
Alternative plan for failed regional block
Preparation for general anaesthetia and difficult intubation
Appropriate post-op care

76. THANK YOU