MORBIDLY OBESE PARTURIENT
Presenter –Dr ShwethaModerator- Prof Arora
www.anaesthesia.co.in [email protected]
CONTENTS
Definition PrevalencePathophysiological changesMaternal and perinatal outcomeAnesthetic managementPost-operative care
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.
WHO CLASSIFICATION
Classification Body mass index (kg/m2)
Associated health risks
Underweight <18.5 LowNormal range 18.5–24.9 AverageOverweight >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
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
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
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
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
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%
Pathophysiological changes in obese pregnant patient
Obesity compounds most of the physiological changes in pregnancy
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
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
Respiratory changes
Vaughan RW. Pulmonary and cardiovascular derangements in the obese patient. In Brown BR, editor. Anesthesia and the Obese Patient. Philadelphia, FA Davis 1082:26.)
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
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
↑ Soft tissue mass of oropharynx
Intermittent obstruction of airway during sleep
Hypoxemia, hypercarbia
Polycythemia, pulmonary hypertension and right ventricular failure
Cardiovascular changes
Gastrointestinal system ↑risk of aspiration of gastric contents &
Mendelson’s syndrome
↓LES tone which is already ↓in pregnancy Hiatus hernia88% 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
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
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
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
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
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.
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
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)
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
Perineal fat and intrapelvic fat deposits near the sigmoid colon and lateral pelvic sidewalls may alter the shape of the vaginal canal
Medicolegal considerations
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
ANESTHETIC MANAGEMENT
Antenatal assessment
Labour analgesia
Ceasarean section -Epidural -Spinal -General Anesthesia -Local infiltration
Post-op care
Ante-natal AssessmentTimingEarly 3rd trimester, or earlier depending on
severity/ other co-morbidities
Re-evaluate on admission for deliveryPerform the consultation / assessmentDevelop anaesthesia planCommunicate anaesthesia planConduct the plan
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
Ante-natal AnaestheticAssessmentSensitive approach - establish rapportHistory - Relevant anaesthesia recordsObstetric history and plansAirway/ventilatory assessmentCVS and other co-morbiditiesL spineIV accessBP monitoringpulse oximetry ABG Others
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
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
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
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
ultrasonographic guidance to facilitate identification of the epidural space
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
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
Combined Spinal Epidural
Success depends on familiarity with technique
AdvantagesMore versatile to titrate the block and doseFaster onset compared to epidural aloneUseful 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
LimitationPotential for failed epidural analgesia after
successful spinal analgesia
cesarean sectionGeneral 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
PremedicationAggressive 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
PositioningProtuberant 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
SPINAL ANESTHESIAConcerns
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
CSF volume in obeseMagnetic 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
LimitationsHigher 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
Continuous Spinal AnesthesiaDural puncture can be intentional or unintentionalCatheter is introduced 2-3cm in subarachnoid space Final density and level are proportional to the dose
in mgs, not the volume delivered
Advantages
ReliableCan be used for analgesia as well as anaesthesia Good control of anesthetic level & duration of blockMinimizes the risk of catastrophic loss of the airway
LimitationsRisk 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
EPIDURAL ANESTHESIA Advantages
Catheter can be placed early in laborCan titrate the dose of local anesthetic agentDecreased incidence of hypotensionDecreased potential for excess motor blockadeFacilitates postoperative analgesiaDecrease the risk of thromboembolic
complications
LimitationsHigh failure rate (25%)Difficulty blocking the sacral roots, resulting in
visceral pain upon stimulation of the bladder
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
GENERAL ANESTHESIADifficult 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
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 equipmentRetrograde intubation equipmentAt 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 detectorRigid ventilating bronchoscope
Use of specialised pillows, ramp (horizontal alignment is achieved between the external auditory meatus and the sternal notch) improves the laryngeal view
Awake intubationCatecholamine 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
Preoxygenation8 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
Anesthetic drugsChoice 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
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
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
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 FiO2large tidal volumePEEPelevation of the panniculus
PEEP increases maternal PaO2, but it may decrease cardiac output and oxygen delivery
Avoid airway obstruction during induction emergence from anesthesia
Extubation must be done when awake in
left lateral position or semi upright position
The Bullard Laryngoscope for Emergency AirwayManagement in a Morbidly Obese ParturientAaron 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
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
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;98:1467-70
Successful delivery in a morbidly obesepatient after failed intubation andregional technique doi:10.1093/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
Post-operative complications
Infections -endometritis -urinary tract infections -wound infection Respiratory -atelectasis -pneumonia -respiratory depression -tracheal reintubation -sleep apneaCardiovascular- cardiac arrest -DVT -pulmonary embolismNerve injuries
Postoperative AnalgesiaMultimodal analgesiaNSAIDS
OPIOIDS
Intramuscular opioid-variable, unpredictable absorption of the drug
Intravenous-opioid more consistent effectrisk of respiratory depressionIntravenous sufentanil- eliminated slowly
reduction in the maintenance dose
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 rapidanalgesia is consistently highMaternal oxygen desaturation limits the dose and
suitable monitoring during use is advisedsuccessful 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
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
Postoperative careMonitored 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
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
SummaryAn ounce of prevention is worth more than apound of treatment Consultant based multidisciplinary approachEarly anaesthetic assessmentProphylactic epidural block, ensuring its
effectivenessAlternative plan for failed regional blockPreparation for general anaesthetia and
difficult intubationAppropriate post-op care
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