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
โข 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
โข Avoid unnecessary respiratory depressant
drugs
9. 9
Volume ReplacementVolume Replacement
โข Avoid rapid rehydration
โข Peripheral perfusion
โข Blood loss
โข 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:
โข Limited TM joint mobility
โข Limited atlanto-occipital mobility
โข Narrow upper airway
โข Small space between mandible and sternal
fat pads
17. โข Arterial catheter to continuously measure BP and
blood gases ( if medically indicated )
โข CVP catheter
โข Urinary catheter
โข Advance monitoring according to Surgery
โข If indicated then BIS
โข PNS
17
20. Airway Management of the Obese
โข Formulate an airway management plan
โข Facial anatomy needs appropriate mask selection
โข Increased mass of soft tissues and Macroglossia
โข Head Tilt & "Sniffing Position" may require
building up towels or blankets under the back,
scapulae, and shoulders, as well as the head and
neck
โข beware of "canโt ventilate, canโt intubate"
situations!
20
21. Dr. Tushar Chokshi 21
Best Position for Intubation
External auditory meatus and sternal notch
at same level
22. โข Mask ventilation may require two persons:
fisrt: two handed mask technique n triple
airway maneuver
2nd
: to ventilate and monitor the
effectiveness
โข Appropriately sized oropharyngeal or
nasopharyngeal airway
โข "Bull Neck"
22
Airway Management of the Obese
23. Have "rescue" alternative airway devices ready
to hand:
e.g., Laryngeal Mask Airway (LMA) or
Intubating LMA (Fastrachโข);
Elastic Gum Bougie;
Lighted Stylet;
Esophageal Combi-Tubeโข;
Fiber-optic Laryngoscope or
Bronchoscope
23
27. โ first intubation attempt should be by the most
experienced intubatorโ
โข 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
27
28. โข Large breasts may get in the way of the
laryngoscope handle (half-size handles are
available).
โข Response to induction agents is less
predictable for intubation
โข Obtuse angle laryngoscope
28
29. โข Confirmation of endotracheal intubation
should be by three or more methods
including either capnometry or capnography
โข All obese patients with airway problems or
impending intubation should have 100%
oxygen
โข In failed Intubation by all methods, in
emergency Percutaneous cricothyrotomy or
surgical tracheostomy
29
30. 30
Anesthetic Considerations:Anesthetic Considerations:
IntraoperativeIntraoperative
โข Awake fiberoptic intubation, if difficult
airway suspected
โข Breath sounds difficult to appreciate
โ ETCO2 more important
โข Even controlled ventilation may require
relatively high FIO2 to prevent hypoxia:
โ Lithotomy
โ Trendelenburg or
โ Prone position
31. 31
Obesity: Anesthetic IssuesObesity: Anesthetic Issues
โข high risk of oesophageal refluxhigh risk of oesophageal reflux
(GERD)(GERD)
โข high risk of aspirationhigh risk of aspiration
โข rapid sequence intubation (RSI)rapid sequence intubation (RSI)
indicatedindicated
โข pre-oxygenationpre-oxygenation
โข cricoid pressurecricoid pressure
โข 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
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. โข Extubation should be delayed
until:
โ Complete reversal of muscle
relaxation
โ Patient fully awake
โข Follows commands
โข 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
โข Respiratory failure is a major
postoperative problem
โข The risk of postoperative hypoxia is
increased by:
โ Preoperative hypoxia and
โ Thoracic or upper abdominal surgery
โข Especially vertical incision
40. 40
Anesthetic Considerations:
Postoperative
โข If the patient is extubated in the operating
room,supplemental O2 should be provided
during
โ Transportation to Recovery room
โข 45 degree head up position
Will unload the diaphragm and
โ Improves oxygenation
โ Improves ventilation
CPAP and BiPAP should be available
41. 41
Anesthetic Considerations:
Postoperative
โข Increased mortality
6.6% vs. 2.7% in non-obese
โข Absolute no sedation post op
โข Other common postoperative
complications include:
Wound infection
Deep venous thrombosis, and
Pulmonary embolism
42. 42
Anesthetic Considerations:
Postoperative
โข PCA(Patient Controlled Analgesia)
โ Can provide good pain relief
โ Dose based on IBW
โข NSAIDs, Local anesthetic infiltration
โข Epidural route is preferred
โ Administration of smaller dose than IV
route
43. ๏Regional anaesthesia:
43
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 โ 25% less LA for Spinal or
Epidural anesthesia because of
โข (Epidural fat and distended epidural veins)
44. โข Combined epidural spinal preferred to
decrease GA requirement
โข Allows for continuation of postoperative
analgesia
โข Epidural anesthesia may โ postoperative
respiratory complications