Anesthesia for Bariatric Surgery

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Anesthesia for Bariatric Surgery

• By Vladimir Melnikov MD
• UT Dept. of Anesthesiology

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Anesthesia for Bariatric Surgery

• Obesity affects millions of persons in the USA
  and around the world
• In 1990 46 billion - 6.8 of all health care
  costs- was spent on obesity related problems in
  the USA.
• Current estimates exceed 100 billion
• The precursors to obesity include
• 1.Genetic tendency
• 2.Environmental effect.
• 3.Education
• 4.Gender, ethnicity
• 5.Socioeconomic

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Anesthesia for Bariatric Surgery

• Medical co-morbidities associated with obesity
• NIDDM
• HTM
• CV DISEASES
• OSA
• Liver Gallbladder diseases
• Arthritis
• Colon and postmenopausal breast cancer
• The risk of dying prematurely increases
• Quality of life issues depression, social
  incompetence, etc.

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Anesthesia for Bariatric Surgery

• Bariatrics is the field of medicine that
  specializes in treating obesity.
• Bariatric surgery is a surgical subspecialty that
  perform operations to treat morbid obesity.
• Most of the patho-physiology medical conditions
  associated with extreme Obesity are reversible
  with sustained weight lose following Bariatric
  surgery.
• Over 100,000 laparoscopic Bariatric procedures
  were performed in the US in 2004.
• Mortality rate for Bariatric surgery is 0.5 - 1!

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Anesthesia for Bariatric Surgery

• Definitions.
• A person is considered obese when the
• amount of body fat increases beyond the
• point where health deteriorates and life
• expectancy is shortened.
• Two general types of obesity
• 1.Central-andriod Obesity associated with
  metabolic
• syndrome
• 2.Periferal-gynecoid Obesity.

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Anesthesia for Bariatric Surgery

• Body Mass Index weight/height x height
• BMI 25 NORMAL
• BMIgt30 OBESE
• BMIgt40 OR gt with medical co-morbidity Morbidly
  obese
• Ideal Weight Height - 100

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Anesthesia for Bariatric Surgery

• PREOPERATIVE EVALUATION
• 1. CV RESPIRATORY SYSTEMS
• a) Tolerance of exercise and ability to
  lie flat.
• b) Symptoms of sleep apnea should be
  sought.
• 2. Airways. Number of abnormalities may
  exist
• a) Limitation of extension and flexion
  of the C-spine.
• b) Restricted mouth opening from
  submental fat.
• c) Large tongue.
• d) Redundant intra oral tissue.
• e) Thyromental distance should be
  assessed.
• f) Infantile type anterior laryngeal
  opening.
• 3. Use of diet tablets (some of them cause
  valvular regurgitation or
• pulmonary HT).

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Anesthesia for Bariatric Surgery

• PREOPERATIVE EVALUATION
• 4. Obesity Hypoventilation Syndrome.
  Pickwickian syndrome
• Obesity, excessive daytime sleepiness, snoring
  cor Pulmonale.
• a) Hypercapnia
• b) Severe hypoxemia
• c) Periodic breathing
• d) Biventricular enlargement (RTgtLT)
• e) Dependent edema.
• f) Polycythemia. Pulmonary edema.
• 5. Metabolic Changes
• Patient scheduled for surgery following
  previous Bariatric surgery may have chronic
  metabolic changes.

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Anesthesia for Bariatric Surgery

• PREOPERATIVE EVALUATION
• CV Systems.
• The degree of cardiac abnormality is correlated
  with the degree of obesity.
• LV dysfunction is often present in young
  asymptomatic patient
• HTN
• Increased Pre-load After-load
• Increased PAP (dyspnea, fatigue, syncope).
• Pulmonary System.
• O2 consumption CO2 production increased
• WOB increased
• Chest wall compliance FRC are low.

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Anesthesia for Bariatric Surgery

• PREOPERATIVE EVALUATION
• GI System.
• No difference in gastric volume or PH between
  lean and obese surgical patient.
• NIDDM and Gastroparesis.
• Fatty Liver w or w/o liver dysfunction is common.
• Gall bladder disease is also common.

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Anesthesia for Bariatric Surgery

• ANESTHETIC CONSIDERATIONS
• PREMEDICATION
• Avoid heavy sedation.
• Medication for chronic HTN
• No diabetic medication on the morning of surgery
• Antibiotics heparine prophylaxis
• H2 antagonist, metoclopramide?
• Monitoring
• NIBP can be obtained from the wrist or ankle.
• A-line highly recommended.
• CVP or PA lines?
• Nerve stimulator needle electrodes are
  recommended (surface electrode

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Anesthesia for Bariatric Surgery

• Pharmacological Considerations
• Drugs are often administered on the basis of dose
  per unit body weight.
• This assumes that clearances and distribution
  volumes are proportional to weight.
• The assumptions 12 are not valid for obese
  patients.

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Anesthesia for Bariatric Surgery

• Induction Agents
• Larger than usual doses of Propofol or
  Thiopental are needed due to increased blood
  volume CO.
• Muscle Relaxants
• Higher doses of succinylcholine 1.5mg/kg IW
  are used.
• Neuromuscular recovery time is similar in
  obese non-obese patient with CIS-ATRACURIUM
  (NIMBEX)
• Complete paralysis is especially important
  during laparoscopy.
• Neuromuscular blockade must be completely
  reversed before extubation.
• OPIOIDS.
• There is no evidence that lipophilic opioids
  last longer in morbidly obese patient.

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Anesthesia for Bariatric Surgery

• TRACHEAL INTUBATION
• Increasing weight or BMI is not a risk factor for
  difficult laryngoscopy.
• FOB intubation is rarely necessary.
• Rapid induction with Propofol Succinylcholine is
  the best for establishing an airway.
• Since mask ventilation can be difficult a second
  person experienced with airway management should
  be present to assist.
• LMA should be available and can serve as abridge
  until an ETT is placed.

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Anesthesia for Bariatric Surgery

• VENTILATION
• VT 10-12ML/KG IW
• FiO2 up to 1.0 may be needed
• High PiP will be needed
• PEEP 5cm H2O
• N2O is avoided
• Pneumoperitoneum can displace diaphragm causing
  the ETT to enter bronchus.
• HEMODNAMIC CHANGES
• The RTP may cause pooling of blood and
  hypotention.

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Anesthesia for Bariatric Surgery

• ANESTHETIC TECHNIQUE.
• OPIOIDS IgtVgt CONTINUOS INFUSION.
• CISATRACURIUM I.V. CONTINUOS INFUSION.
• INHALATION ANESTHETIC DEFLURANE.
• POSTOPERATIVE CONSIDERATIONS.
• Position Upper body elevated 30-45 degree.
• Oxygenation Restoration of normal pulmonary
  function after abdominal surgery may take several
  days.
• Nasal or mask O2.
• Nasal CPAP
• BiPAP
• Analgesia
• An opioid PCA dosed on the basis of IW
• NSAIDs