THE OBESE PARTURIENT HARRY SINGH, MD DEPT. OF ANESTHESIOLOGY UTMB
INDICES OF OBESITY AND THEIR PARAMETERS <ul><li>Index Definition Values </li></ul><ul><li>________________________________...
DEFINITIONS AND INCIDENCE <ul><li>Normal BMI: 25 </li></ul><ul><li>Overweight –up to 20% more than ideal body weight or BM...
TYPES OF OBESITY <ul><li>Android Obesity : Truncal distribution of fat </li></ul><ul><li>Associated with high incidence of...
PATHOPHYSIOLOGIC CHANGES <ul><li>PULMONARY : </li></ul><ul><li>↑  O 2  consumption and ↑ CO 2  production: </li></ul><ul><...
EFFECT OF POSITION ON LUNG VOLUMES In obesity, decreased chest wall compliance results in a functional residual capacity (...
PICKWICKIAN SYNDROME OR OHS <ul><li>8% of obese patients </li></ul><ul><li>Alveolar hypoventilation, somnolence and morbid...
PATHOPHYSIOLOGIC CHANGES <ul><li>CARDIOVASCULAR : </li></ul><ul><li>↑  Blood Volume and ↑Cardiac Output  ( ↑  Stroke volum...
PATHOPHYSIOLOGIC CHANGES <ul><li>ENDOCRINE AND METABOLIC : </li></ul><ul><li>↑  Incidence of adult onset diabetes </li></u...
PATHOPHYSIOLOGIC CHANGES <ul><li>GASTROINTESTINAL : </li></ul><ul><li>↑  Intragastric and intrabdominal pressures </li></u...
CHANGES IN THE AIRWAY <ul><li>Short neck, ↓ chin to chest distance </li></ul><ul><li>Limited flexion of cervical spine </l...
MATERNAL MORTALITY <ul><li>Obesity risk factor in 12 of 15 anesthesia related deaths in Michigan between 1972 to 1984: Fai...
MATERNAL COMPLICATIONS <ul><li>47% of obese parturients have antenatal disease </li></ul><ul><li>Gestational diabetes (Odd...
OBSTETRIC COMPLICATIONS <ul><li>Fetal macrosomia (Odds ratio:3.82): Maternal obesity, diabetes and increased gestational a...
PERINATAL OUTCOME <ul><li>Birth asphyxia and trauma due to shoulder dystocia </li></ul><ul><li>Instrumental delivery (Odds...
EPIDURAL ANALGESIA (KEY POINTS) <ul><li>Early insertion of epidural desirable in obese parturients undergoing trial of lab...
EPIDURAL ANALGESIA (KEY POINTS) <ul><li>Higher incidence of failed epidural, unilateral block and more attempts to identif...
EPIDURAL  ANALGESIA (KEY POINTS) <ul><li>Lateral sitting or semi recumbent position to minimize airway closure and aortoca...
SPINAL ANESTHESIA (KEY POINTS ) <ul><li>Negative correlation between the degree of obesity and dose requirement of local a...
GENERAL ANESTHESIA (KEY POINTS) <ul><li>Increased incidence of complications with GETA </li></ul><ul><li>The operating roo...
GENERAL ANESTHESIA(KEY POINTS) <ul><li>Consider multimodal aspiration prophylaxis </li></ul><ul><li>Difficult mask ventila...
GENERAL ANESTHESIA (KEY POINTS)  <ul><li>Rapid sequence induction should not be performed in obese parturients with antici...
GENERAL ANESTHESIA  (KEY POINTS) <ul><li>Drug doses may be based on actual or ideal body weight </li></ul><ul><li>Highly l...
POSTOPERATIVE MANAGEMENT <ul><li>Patient should be kept  in semi-recumbent or reverse trendelenberg position </li></ul><ul...
CONCLUSIONS <ul><li>Obesity increases the risk of anesthesia related maternal mortality. Airway complications represent th...
SUGGESTED READINGS <ul><li>D’Angelo R, Dewan DD. Obesity in Principles and Practice of Anesthesia, Editor David H Chestnut...
HAVE A GOOD DAY!
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THE OBESE PARTURIENT

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THE OBESE PARTURIENT

  1. 1. THE OBESE PARTURIENT HARRY SINGH, MD DEPT. OF ANESTHESIOLOGY UTMB
  2. 2. INDICES OF OBESITY AND THEIR PARAMETERS <ul><li>Index Definition Values </li></ul><ul><li>_______________________________________________________________ </li></ul><ul><li>Overweight 20% > ideal </li></ul><ul><li>Obesity > 20% over ideal </li></ul><ul><li>Morbid obesity Ideal weight x 2 </li></ul><ul><li>Broca index Ideal female weight Ht (cm) – 105 </li></ul><ul><li>Body Mass Wt (kg) Normal = 25, obese > 30 </li></ul><ul><li>(Quetelet) index Ht (m) 2 </li></ul><ul><li>3 Ht (in) </li></ul><ul><li>Ponderal index √ Wt (lb) Obese < 11.6 </li></ul><ul><li>______________________________________________________________ </li></ul><ul><li>From Dewan DM, The obese parturient. In James FM, Wheeler AS, Dewan DM, editors. </li></ul><ul><li>Obsteric Anesthesia: The Complicated Patient , 2 nd ed. Philadelphia, FA Davis, 1988:468. </li></ul>
  3. 3. DEFINITIONS AND INCIDENCE <ul><li>Normal BMI: 25 </li></ul><ul><li>Overweight –up to 20% more than ideal body weight or BMI 25-29 </li></ul><ul><li>Obesity : BMI > 30 </li></ul><ul><li>Morbid Obesity : twice the ideal body weight or BMI > 40 </li></ul><ul><li>Recent data from National Center for Health Statistics suggests 54% Americans overweight and 21% obese </li></ul><ul><li>6%-10% parturients morbidly obese </li></ul>
  4. 4. TYPES OF OBESITY <ul><li>Android Obesity : Truncal distribution of fat </li></ul><ul><li>Associated with high incidence of cardiovascular disorders </li></ul><ul><li>Gynecoid Obesity : Fat distributed to thighs and buttocks </li></ul><ul><li>Associated with pregnancy </li></ul>
  5. 5. PATHOPHYSIOLOGIC CHANGES <ul><li>PULMONARY : </li></ul><ul><li>↑ O 2 consumption and ↑ CO 2 production: </li></ul><ul><li>Secondary to metabolic activity of adipose tissue </li></ul><ul><li>↑ Minute Ventilation </li></ul><ul><li>Reduced chest wall compliance (Restrictive defect) </li></ul><ul><li>↓ Functional Residual Capacity and Residual Volume </li></ul><ul><li>FRC may be less than closing capacity->airway closure during tidal ventilation->V/Q mismatch and shunting </li></ul><ul><li>Accentuated in supine, trendelenberg or lithotomy position </li></ul>
  6. 6. EFFECT OF POSITION ON LUNG VOLUMES In obesity, decreased chest wall compliance results in a functional residual capacity ( FRC ) that decreases at the expense of expiratory reserve volume ( ERV ). Closing capacity ( CC ) stays normal. (From Vaughan RW. Pulmonary and cardiovascular derangements in the obese patient. In Brown BR, editor. Anesthesia and the Obese Patient. Philadelphia, FA Davis 1082:26.)
  7. 7. PICKWICKIAN SYNDROME OR OHS <ul><li>8% of obese patients </li></ul><ul><li>Alveolar hypoventilation, somnolence and morbid obesity </li></ul><ul><li>↑ Soft tissue mass of oropharynx -> Intermittent obstruction of airway during sleep </li></ul><ul><li>Hypoxemia, hypercarbia </li></ul><ul><li>Polycythemia, pulmonary hypertension and right ventricular failure </li></ul><ul><li>Pulmonary embolism and pneumonia </li></ul>
  8. 8. PATHOPHYSIOLOGIC CHANGES <ul><li>CARDIOVASCULAR : </li></ul><ul><li>↑ Blood Volume and ↑Cardiac Output ( ↑ Stroke volume) </li></ul><ul><li>Blood flow through adipose tissue-2 -3 ml/min/100 g </li></ul><ul><li>Morbid obesity: 50% mild HTN, 5-10% severe HTN </li></ul><ul><li>Doubling of incidence of CAD </li></ul><ul><li>↑ Afterload and preload (↑BP and ↑Blood Volume) </li></ul><ul><li>↑ Left ventricular end diastolic pressure and LV hypertrophy </li></ul><ul><li>More vulnerable to pulmonary hypertension </li></ul><ul><li>Airway obstruction or hypoxemia-> ↑ PAP or PAOP </li></ul>
  9. 9. PATHOPHYSIOLOGIC CHANGES <ul><li>ENDOCRINE AND METABOLIC : </li></ul><ul><li>↑ Incidence of adult onset diabetes </li></ul><ul><li>Impaired glucose tolerance </li></ul><ul><li>Resistance to insulin </li></ul><ul><li>Hypertrophy of Islets of Langerhans </li></ul><ul><li>High serum triglycerides </li></ul><ul><li>High serum cholesterol </li></ul><ul><li>↑ Incidence of IHD </li></ul>
  10. 10. PATHOPHYSIOLOGIC CHANGES <ul><li>GASTROINTESTINAL : </li></ul><ul><li>↑ Intragastric and intrabdominal pressures </li></ul><ul><li>↓ Lower esophageal sphincter tone </li></ul><ul><li>↑ Hiatus Hernia </li></ul><ul><li>Strong correlation between BMI and reflux symptoms (Odds ratio 6.3 for women with BMI>35) </li></ul><ul><li>80% obese patients have gastric pH < 2.5 </li></ul><ul><li>86% obese patients have gastric volume>25mL </li></ul><ul><li>75% patients at risk of aspiration pneumonitis </li></ul><ul><li>Combination of pregnancy and obesity increases the risk of aspiration pneumonitis </li></ul>
  11. 11. CHANGES IN THE AIRWAY <ul><li>Short neck, ↓ chin to chest distance </li></ul><ul><li>Limited flexion of cervical spine </li></ul><ul><li>Nonexistent atlantooccipital gap </li></ul><ul><li>Limited atlantooccipital extension and bowing of cervical spine and forward displacement of larynx </li></ul><ul><li>Adiposity of the face, shoulders, neck and breasts </li></ul><ul><li>Narrow pharyngeal opening due to enlarged tongue and fleshy pharyngeal and supralaryngeal tissues </li></ul><ul><li>↑ Incidence of failed or difficult intubation </li></ul><ul><li>33% incidence of difficult intubation in obese parturients </li></ul><ul><li>Percutaneous cricothyrotomy may be difficult due to difficulty to palpate landmarks </li></ul>
  12. 12. MATERNAL MORTALITY <ul><li>Obesity risk factor in 12 of 15 anesthesia related deaths in Michigan between 1972 to 1984: Failed intubation leading cause of death </li></ul><ul><li>4 of 7 maternal deaths in Chicago Maternity Hospital in women > 200 lbs </li></ul><ul><li>12% of all maternal deaths in obese women between 1963 and 1997 in Minnesota: Pulmonary embolus leading cause of death </li></ul><ul><li>Anesthesia, surgery and pregnancy additively increase the mortality and morbidity in these patients . </li></ul>
  13. 13. MATERNAL COMPLICATIONS <ul><li>47% of obese parturients have antenatal disease </li></ul><ul><li>Gestational diabetes (Odds ratio: 4.00) </li></ul><ul><li>Gestational hypertension (Odds ratio: 3.20) </li></ul><ul><li>Preeclampsia (Odds ratio:8.20) </li></ul><ul><li>Incidence of cesarean delivery (Odds ratio:2.69) </li></ul><ul><li>Shoulder dystocia (Odds ratio:3.14): most common indication for emergency CS in these patients </li></ul><ul><li>In one study of 117 patients, 62% CS rate in women > 300 lbs </li></ul><ul><li>Another study of 107 patients found 58% CS rate in women 200-504 lbs </li></ul><ul><li>Blood loss >1000 ml for cesarean delivery </li></ul><ul><li>Prolonged duration of surgery </li></ul><ul><li>Increased incidence of postpartum hemorrhage </li></ul>
  14. 14. OBSTETRIC COMPLICATIONS <ul><li>Fetal macrosomia (Odds ratio:3.82): Maternal obesity, diabetes and increased gestational age contributory factors </li></ul><ul><li>Meconium aspiration (Odds ratio:2.85) </li></ul><ul><li>Late decelerations (Odds ratio:2.52) </li></ul><ul><li>Prolonged gestation </li></ul><ul><li>Dysfunctional labor patterns </li></ul><ul><li>Twins/breech presentation </li></ul><ul><li>Fetal umbilical cord accidents </li></ul><ul><li>Increased incidence of induction of labor due to prolonged gestation </li></ul><ul><li>High incidence of failed inductions </li></ul><ul><li>Increased incidence of FTP and prolonged second stage of labor </li></ul>
  15. 15. PERINATAL OUTCOME <ul><li>Birth asphyxia and trauma due to shoulder dystocia </li></ul><ul><li>Instrumental delivery (Odds ratio:1.34) </li></ul><ul><li>Neonatal death (Odds ratio:3.41) </li></ul><ul><li>Intrauterine fetal demise (Odds ratio:2.79) </li></ul><ul><li>Higher pregnancy weight associated with </li></ul><ul><li>increased risk of late fetal death </li></ul><ul><li>Increased neural tube defects and other congenital malformations </li></ul><ul><li>Neonatal hypoglycemia more frequent </li></ul><ul><li>Increased frequency of neonatal intensive care admissions </li></ul>
  16. 16. EPIDURAL ANALGESIA (KEY POINTS) <ul><li>Early insertion of epidural desirable in obese parturients undergoing trial of labor </li></ul><ul><li>Landmarks invariably difficult to palpate </li></ul><ul><li>May consider ultrasound guidance for midline bony structures with assistance from obstetrician </li></ul><ul><li>Small directional errors exaggerated with increasing depth of epidural space </li></ul><ul><li>Patient can help guide to the midline by telling if she senses pressure from needle advancement to right or left </li></ul><ul><li>Have extra long needles available if necessary </li></ul><ul><li>Non functioning epidural should be replaced immediately </li></ul><ul><li>Catheter should be inserted at least 5 cm in epidural space as risk of catheter displacement high in obese parturients </li></ul>
  17. 17. EPIDURAL ANALGESIA (KEY POINTS) <ul><li>Higher incidence of failed epidural, unilateral block and more attempts to identify the space in morbidly obese </li></ul><ul><li>94% of obese parturients (>300 lbs) achieved successful analgesia in one study </li></ul><ul><li>Catheter had to be replaced once in 46% of these patients </li></ul><ul><li>Two or more times in 21% of these patients </li></ul><ul><li>May consider a planned wet tap with your epidural needle </li></ul><ul><li>If one occurs unexpectedly, consider converting to a continuous spinal with dilute local anesthetic and opioid for labor analgesia (usually 2ml/hr of 0.125% bupivacaine with fentanyl optimal) </li></ul><ul><li>More concentrated local anesthetic for cesarean delivery (1-2 ml of 0.75% bupivacaine with fentanyl and durmaorph) </li></ul><ul><li>Postdural puncture headache rare in morbidly obese patients </li></ul>
  18. 18. EPIDURAL ANALGESIA (KEY POINTS) <ul><li>Lateral sitting or semi recumbent position to minimize airway closure and aortocaval compression </li></ul><ul><li>O 2 administration throughout labor to prevent hypoxemia </li></ul><ul><li>Epidural decreases O 2 consumption and improves oxygenation and prevents increases in cardiac output by inhibiting catecholamine release during labor </li></ul><ul><li>Optimal titration of local anesthetic can prevent hypotension and excess motor block </li></ul><ul><li>Epidural advantageous due to frequent need for operative vaginal or cesarean delivery in these patients </li></ul><ul><li>Can also be used for postoperative pain management </li></ul><ul><li>CSE not the technique of choice for labor analgesia in obese parturients due to delayed assessment of functionality of the epidural </li></ul>
  19. 19. SPINAL ANESTHESIA (KEY POINTS ) <ul><li>Negative correlation between the degree of obesity and dose requirement of local anesthetic </li></ul><ul><li>Higher block may be due to decreased CSF volume (engorged epidural venous plexus), exaggerated curvature of lumbar spine, pelvic fat and hormonal changes of pregnancy </li></ul><ul><li>High incidence of hypotension following spinal due to higher and variable extension of autonomic blockade in obese patients </li></ul><ul><li>High block may exaggerate hypoxemia in these patients </li></ul><ul><li>Single shot spinal disadvantageous due to prolonged surgery in these patients </li></ul><ul><li>Continuous spinal with epidural catheter may be advantageous in patients for emergent/urgent CS with anticipated difficult airway </li></ul><ul><li>CSE technique of choice for scheduled/elective CS </li></ul><ul><li>CSE set with Gertie Marx spinal needle (12.4 cm) may be necessary for some these patients </li></ul>
  20. 20. GENERAL ANESTHESIA (KEY POINTS) <ul><li>Increased incidence of complications with GETA </li></ul><ul><li>The operating room should be prepared with a bed of appropriate width and strength, and wider arm supports and pads </li></ul><ul><li>Most operating room beds only rated for weights up to 300 lbs </li></ul><ul><li>The patient should be interviewed early in course of labor or preferably during antepartum visit </li></ul><ul><li>Consider additional tests during preop visit like CXR, EKG and PFT with ABGs </li></ul><ul><li>Thorough airway evaluation mandatory </li></ul><ul><li>Considerable proportion of maternal mortality associated with GETA during cesarean delivery </li></ul><ul><li>GETA should only be confined to cases where it is indispensable to save mother or fetus </li></ul><ul><li>Safety of mother of paramount importance and overrides fetal considerations </li></ul>
  21. 21. GENERAL ANESTHESIA(KEY POINTS) <ul><li>Consider multimodal aspiration prophylaxis </li></ul><ul><li>Difficult mask ventilation, laryngoscopy and intubation should be anticipated; however, obesity alone doesn’t predict difficult airway </li></ul><ul><li>13% obese patients pose difficulty with intubation </li></ul><ul><li>30% obese parturients pose difficulty with intubation </li></ul><ul><li>Landmarks for block obscure, therefore, consider topical anesthesia of airway with 4% lidocaine </li></ul><ul><li>Direct laryngoscopy following topical anesthesia can be considered for anticipated difficult airway </li></ul><ul><li>Obesity+MP IV: Consider fiberoptic intubation </li></ul><ul><li>Positioning for airway important: the head, neck and shoulder should be raised, there should be straight line between sternal notch and the external auditory meatus and patient should be in reverse trendelenberg position </li></ul>
  22. 22. GENERAL ANESTHESIA (KEY POINTS) <ul><li>Rapid sequence induction should not be performed in obese parturients with anticipated difficult airway </li></ul><ul><li>Patient should be fully denitrogenated with 100% O2 for 3-5 min before rapid sequence induction </li></ul><ul><li>Additional experienced hands must be available for assistance during administration of GETA </li></ul><ul><li>Have ancillary airway equipment such as fiberoptic bronchoscope, short handle laryngoscope and an assortment of laryngeal mask airways available </li></ul><ul><li>Higher FiO2, tidal volumes and PEEP may be required to maintain adequate SaO2 </li></ul><ul><li>Effect of muscle relaxant during surgery may be overestimated, whereas, reversal effect may be underestimated </li></ul>
  23. 23. GENERAL ANESTHESIA (KEY POINTS) <ul><li>Drug doses may be based on actual or ideal body weight </li></ul><ul><li>Highly lipophilic drugs (barbiturates, benzodiazepines) have considerably increased volume of distribution with higher doses and longer elimination half-lives </li></ul><ul><li>Non-lipophilic or weakly lipophilic drugs administered based on lean body mass </li></ul><ul><li>Emergence faster after desflurane than sevoflurane or isoflurane anesthesia and their O2 saturations higher with desflurane in PACU </li></ul><ul><li>Extubate conservatively and in reverse trendelenburg position </li></ul><ul><li>The incidence of dangerous postextubation obstruction is ≈ 5% in patients with OSA, so extubate with oral or nasal airway in place. </li></ul><ul><li>If concerned about possible re-intubation, extubate over an airway exchanger </li></ul>
  24. 24. POSTOPERATIVE MANAGEMENT <ul><li>Patient should be kept in semi-recumbent or reverse trendelenberg position </li></ul><ul><li>Continue monitoring for hypoxia and hypoventilation and consider CPAP mask if OSA a problem </li></ul><ul><li>A monitored or step down bed may be more appropriate location for recovery in the L&D </li></ul><ul><li>Hospitalization often prolonged </li></ul><ul><li>Wound dehiscence and infection more common </li></ul><ul><li>Increased incidence of postoperative pulmonary complications including hypoxemia, atelectasis and pneumonia </li></ul><ul><li>Vertical abdominal incision more likely to cause hypoxemia </li></ul><ul><li>Increased risk of deep venous thrombosis and pulmonary thromboembolism-consider anticoagulation soon after surgery with LMWH or unfractionated heparin </li></ul><ul><li>Adequate postoperative analgesia essential to promote early ambulation and to decrease risk of pulmonary complications </li></ul>
  25. 25. CONCLUSIONS <ul><li>Obesity increases the risk of anesthesia related maternal mortality. Airway complications represent the most common cause of anesthesia-related maternal mortality </li></ul><ul><li>Unlike most parturients, associated co-morbidities complicate management of morbidly obese parturients </li></ul><ul><li>The obese parturient is at increased risk for fetal macrosomia, shoulder dystocia and cesarean section </li></ul><ul><li>Early administration of epidural is advisable in obese parturients undergoing trial of labor; a non-functioning epidural should be replaced immediately </li></ul><ul><li>The anesthetic management requires patience, planning and close collaboration amongst involved physicians </li></ul>
  26. 26. SUGGESTED READINGS <ul><li>D’Angelo R, Dewan DD. Obesity in Principles and Practice of Anesthesia, Editor David H Chestnut, Elsevier Mosby, PA. </li></ul><ul><li>Hawkins JL. Labor and Delivery Management of the Morbidly Obese Parturient. 2005 IARS Meeting Review Course Lectures. </li></ul><ul><li>Endler GC, Mariona FG, Solok RJ, Stevenson LB. Anesthesia related maternal mortality in Michigan. Am J Obstet Gynecol 1988; 159:187-93. </li></ul>
  27. 27. HAVE A GOOD DAY!

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