anaesthesia for bariatric surgery

1. ANAESTHETIC CONSIDERATIONS FOR
BARIATRIC SURGERY
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2. PREOPERATIVE EVALUATION
Preoperative assessment should
include:
Special attention should be paid to:
Circulatory
Pulmonary, and
Hepatic functions

3. PREOPERATIVE EVALUATION
Preoperative assessment should
include consideration of:
 Hypertension
 Diabetes
 Heart failure and
 Obesity-hypoventilation syndrome
 Results of the sleep study
 An AHI score greater than 30,implying severe
sleep apnea is a warning sign and a predictor of
rapid and severe desaturation at induction

4.  the history of previous surgeries,
their anaesthetic challenges(i.e. ease or
difficulty in securing the airway, intravenous
access)
 need for icu admission
 surgical outcomes and
 weight of the patient at that time

5. 5
Increased risk for aspiration pneumonitis
• As obesity is associated with GIT
pathophysiology including:
hiatal hernia
gastroesophageal reflux
poor gastric emtying, and
hyperacidic gastric fluid
So routine pretreatment with
H2 antagonists and metoclopramide
should be considered
• Avoid unnecessary respiratory depressant
drugs

6. Recommended preoperative laboratory
evaluations include:
• Complete blood count
• Renal function tests,
• Serum electrolytes
• Liver function test
• Coagulation profile
• Fasting blood glucose
• Lipid profile

7. Assess cardiopulmonary reserve
with:
ECG & X-ray Chest, if necessary
echocardiography
Arterial blood gas
Pulmonary function tests
Thyroid Function test

8. 8
Vascular AccessVascular Access
• Challenging at best
• Central line placement.

9. 9
Volume ReplacementVolume Replacement
• Avoid rapid rehydration
• Peripheral perfusion
• Blood loss
• Administer Hetastarch at recommended volumes
per kilogram of IBW 20 mL/kg
Albumin 5% and 25% used as indicated
Support circulatory volume and oncotic pressure.
Replace blood loss with crystalloid -3:1 ratio

10. SPECIAL CHALLENGES:
Obese patients present special challenges for
the anaesthesiologists in:
 Airway management
 Positioning
 Monitoring
 Choice of anaesthetic technique and agents
 Pain control and
 Fluid management

11. PATIENT POSITIONING
do require extra care in positioning
 In the supine position ,
In the prone position
Pressure points
 Lateral decubitus position

12. Obese patients have excess axillary tissue
In the lithotomy position: support with regular
stirrups
Duration :should be kept as short as possible
Specially designed tables or two regular designed
tables joined together

13. Regular OR tables have a max wt limit of app 205
kg but operating tables capable of holding upto
455 kg with a little extra width
Well strapped to the operating table

14. 14
PREOPERATIVE AIRWAYPREOPERATIVE AIRWAY
ASSESSMENTASSESSMENT
Particular attention should be paid to the
airway because they are often difficult to
intubate as a result of:
• Limited TM joint mobility
• Limited atlanto-occipital mobility
• Narrow upper airway
• Small space between mandible and sternal
fat pads

15. Neck CircumferenceNeck Circumference
Is an independent predictor of difficult
intubation
If it increase by 13 % then difficult intubation
is counted
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16. MONITORINGMONITORING
• ECG
• Pulse Oxymeter
• Blood pressure
• Temperature
• Inspired oxygen concentration
• Capnography
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17. • Arterial catheter to continuously measure BP and
blood gases ( if medically indicated )
• CVP catheter
• Urinary catheter
• Advance monitoring according to Surgery
• If indicated then BIS
• PNS
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18. 18
Anesthetic Considerations:Anesthetic Considerations:
InductionInduction
• Prepare for difficult intubation
• Prepare for difficult mask ventilation
• Induction may cause airway collapse
– Leading to upper airway obstruction

19. 19
Anesthetic Considerations:Anesthetic Considerations:
InductionInduction
• Consider awake intubation
– Avoids airway collapse
– Minimal to no sedation
– LMA is good alternative
• Consider tracheostomy kit and
surgeon stand by.

20. Airway Management of the Obese
• Formulate an airway management plan
• Facial anatomy needs appropriate mask selection
• Increased mass of soft tissues and Macroglossia
• Head Tilt & "Sniffing Position" may require
building up towels or blankets under the back,
scapulae, and shoulders, as well as the head and
neck
• beware of "can’t ventilate, can’t intubate"
situations!
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21. Dr. Tushar Chokshi 21
Best Position for Intubation
External auditory meatus and sternal notch
at same level

22. • Mask ventilation may require two persons:
fisrt: two handed mask technique n triple
airway maneuver
2nd
: to ventilate and monitor the
effectiveness
• Appropriately sized oropharyngeal or
nasopharyngeal airway
• "Bull Neck"
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Airway Management of the Obese

23. Have "rescue" alternative airway devices ready
to hand:
e.g., Laryngeal Mask Airway (LMA) or
Intubating LMA (Fastrach™);
Elastic Gum Bougie;
Lighted Stylet;
Esophageal Combi-Tube™;
Fiber-optic Laryngoscope or
Bronchoscope
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24. Bullard laryngoscope

25. Fastrach lma:

26. Obtuse angle larygoscope

27. “ first intubation attempt should be by the most
experienced intubator”
• first best attempt determines difficult or
impossible laryngoscopy or intubation,
change to either Rescue Airway plan
(if patient condition is critical), or
early Fiberoptic Intubation before airway
trauma worsens the situation
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28. • Large breasts may get in the way of the
laryngoscope handle (half-size handles are
available).
• Response to induction agents is less
predictable for intubation
• Obtuse angle laryngoscope
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29. • Confirmation of endotracheal intubation
should be by three or more methods
including either capnometry or capnography
• All obese patients with airway problems or
impending intubation should have 100%
oxygen
• In failed Intubation by all methods, in
emergency Percutaneous cricothyrotomy or
surgical tracheostomy
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30. 30
Anesthetic Considerations:Anesthetic Considerations:
IntraoperativeIntraoperative
• Awake fiberoptic intubation, if difficult
airway suspected
• Breath sounds difficult to appreciate
– ETCO2 more important
• Even controlled ventilation may require
relatively high FIO2 to prevent hypoxia:
– Lithotomy
– Trendelenburg or
– Prone position

31. 31
Obesity: Anesthetic IssuesObesity: Anesthetic Issues
• high risk of oesophageal refluxhigh risk of oesophageal reflux
(GERD)(GERD)
• high risk of aspirationhigh risk of aspiration
• rapid sequence intubation (RSI)rapid sequence intubation (RSI)
indicatedindicated
• pre-oxygenationpre-oxygenation
• cricoid pressurecricoid pressure
• succinylcholinesuccinylcholine

32. Commonly used anaesthetic drugs can be dosed
according to total body weight(TBW) or IBW
based on lipid solubility
Lean body mass is a good weight approximation
to use when dosing hydrophilic medications

33. Lean body mass is usually approximated as 120%
IBW( TBW- The adipose tissue)
The volume of distribution is changed in obese
patients with regard to lipophilic drugs
Three exceptions to this rule are
digoxin,procainamide,and remifentanil,which
even though highly lipophilic have no
relationship between properties of drug and Vd

34. PharmacologyPharmacology
AS PER TBW-
 thiopental
Midazolam
Succinylcholine
Atracurium
Cisatracurium
Fentanyl and
sufentanil
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35. 35
Goals for Maintenance of Anesthesia
• Strict maintenance of airway
• Adequate skeletal muscle relaxation
• Optimum oxygenation
• Maintenance of anesthesia with
inhalation and intravenous agents
• Avoid residual effects of muscle relaxants
• Appropriate intraoperative and
postoperative tidal volume
• Effective postoperative analgesia.

36. AS PER IBW-
Propofol
Vecuronium
Rocuronium and
Remifentanil
Exceptions-maintainance doses of propofol
should be based on TBW and on IBW for
sufentanil

37. 37
VENTILATIONVENTILATION
In morbidly obese patients, the best strategy for
ventilation is to deliver TV according to IBW (8-10
ml/kg )
Apply 5 cm H2O PEEP in order to decrease the
incidence of atelectasis.
 Minute ventilation and ETCO2 need to be monitored
closely
Usually use pressure control ventilation

38. • Extubation should be delayed
until:
– Complete reversal of muscle
relaxation
– Patient fully awake
• Follows commands
• An obese patient should remain
intubated, until there is no doubt
that an adequate airway and tidal
volume will be maintained

39. 39
Anesthetic Considerations:
Postoperative
• Respiratory failure is a major
postoperative problem
• The risk of postoperative hypoxia is
increased by:
– Preoperative hypoxia and
– Thoracic or upper abdominal surgery
• Especially vertical incision

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Anesthetic Considerations:
Postoperative
• If the patient is extubated in the operating
room,supplemental O2 should be provided
during
– Transportation to Recovery room
• 45 degree head up position
Will unload the diaphragm and
– Improves oxygenation
– Improves ventilation
CPAP and BiPAP should be available

41. 41
Anesthetic Considerations:
Postoperative
• Increased mortality
6.6% vs. 2.7% in non-obese
• Absolute no sedation post op
• Other common postoperative
complications include:
Wound infection
Deep venous thrombosis, and
Pulmonary embolism

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Anesthetic Considerations:
Postoperative
• PCA(Patient Controlled Analgesia)
– Can provide good pain relief
– Dose based on IBW
• NSAIDs, Local anesthetic infiltration
• Epidural route is preferred
– Administration of smaller dose than IV
route

43. Regional anaesthesia:
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Is a useful alternative to GA
Technically more difficult
Is easier in the lumbar region
Longer needles and the sitting position
Ultrasound and Fluoroscopy
Require 20 – 25% less LA for Spinal or
Epidural anesthesia because of
• (Epidural fat and distended epidural veins)

44. • Combined epidural spinal preferred to
decrease GA requirement
• Allows for continuation of postoperative
analgesia
• Epidural anesthesia may ↓ postoperative
respiratory complications