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Anesthesia for bariatric surgery asma
1. By
Dr. Asmaa Sobhy Abd-ellah
Lecturer of Anesthesia and Intensive Care
Alzahraa university hospital
Al-Azhar university
3/21/2013
2. Bariatric surgery is a surgical subspecialty that perform
operations to treat morbid obesity.
Over 100,000 laparoscopic Bariatric procedures were
performed in the US in 2004
Most of the patho-physiology & medical conditions
associated with extreme Obesity are reversible with
sustained weight loss following Bariatric surgery.
3. Indications Contraindications
• BMI > 40 kg/ m2
• BMI > 30 kg/ m2
with co-morbidities
• Failed medical
treatment
Unstable angina
Inflammatory diseases of the
gastrointestinal tract
upper gastrointestinal
bleeding (varices);
chronic pancreatitis;
laparoscopic surgery may be
technically difficult in
patients weighing >180 kg
and this may be considered a
relative contraindication.
4. Surgical approaches designed to treat obesity can be classified as restrictive or
malabsorptive
1-Restrictive procedures 2- Malabsorptive
A-Vertical-banded gastroplasty,
B-Adjustable laparoscopic
gastric banding
procedures
A- Jejunoileal bypass
B- Biliopancreatic diversion.
C - Gastric bypass
involves the creation of a small
gastric pouch to cause early
satiety;
Involve bypass of a portion of the
small intestine. With the drawbacks of
relative technical complexity and a risk
of malnutrition and vitamin
deficiencies, along with the need for
close follow-up.
5. Definitions :
Ch. Metabolic disorder that is primarily caused by over
consumption of caloric substances
AHA defines obesity by BW> 30% of IBW
6. Ideal Weight = Height – 100 or 105 (Brocca)
Body Mass Index = weight (kg)/ height ( m) 2
BMI = 25 kg/m2 – NORMAL
BMI > 30 – 49.9 kg/m2 OBESE subdivided into classes
BMI >50 kg/m2 super-obese
Health risks increase with the degree of obesity and with
increased abdominal distribution of weight.
Men with a waist measurement of 40 in. and
women with a waist measurement of 35 in. are at increased
health risk.
7. NIDDM HTN
Colon and breast
cancer obesity
Quality of life issues: depression, social
incompetence
CV disease
OSA
Liver & Gallbladder
diseases
Arthritis
Risk of sudden
death
8. 1. CV System 2- Respiratory system
LV dysfunction is often present in young
asymptomatic patient
high cardiac output and an increased
circulating volume
HTN
Increased Pre-load & After-load
Increased PAP (dyspnea, fatigue, syncope).
Fatty Infiltration of conductive system
Risk of arrhythmias
O2 consumption & CO2 production
increased
WOB increased
Chest wall compliance low
FRC<CC
Decrease lung volumes
Obesity- hypovetilation syndrome
12. 3. Airways
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) small Thyromental distance.
f) Infantile type anterior laryngeal opening.
13. 4 -GI System.
Gastroparesis as obese persons have NIDDM .
Increase incidence of reflux, haiatal hernia and
increase abdominal pressure
Fatty Liver w or w/o liver dysfunction is common.
Gall bladder disease is also common
5 –Renal System
Renal clearance of drugs is increased in obesity because
of increased renal blood flow and glomerular filtration rate
(GFR)
14.
15. cardio-respiratory
& airway
Co-morbidities:
History of previous surgeries and
their anesthetic challenges and
need for ICU admission
16. Assessed for use of weight reducing substances, herbal
supplements, and anorexiant drugs (drugs that acting on the
brain to reduce the appetite).
Chronic use of noradrenergic and serotonergic therapy can
produce hypertension, tachycardia, anxiety, psychosis, and
catecholamine depletion
Patient scheduled for surgery following previous Bariatric surgery
may have chronic metabolic changes
18. Explanations of anticipated events during
preoperative preparation (multiple venipunctures,
central and arterial lines insertions, awake
intubation, pain management) and protection of
the patient’s privacy will relieve anxiety
19.
20. Medication for chronic HTN
No diabetic medication on the morning of
surgery
Avoid sedation.
Antibiotics
DVT prophylaxis (heparin –compressive stocks –
inferior vena cava filter)
Prophylaxis for aspiration
21. NIBP can be obtained from the wrist or ankle
End-tidal co2 monitoring
A-line highly recommended for invasive BP monitoring and
ABG sampling.
CV lines especially if difficult peripheral IV line or
supermoribid obese
Urinary catheter
Nerve stimulator: needle electrodes are recommended
(surface electrode)
22. Transfer
Sufficient manpower must be available to help transfer the
patient from a bed to the operating table, and special inflation
mattresses have been designed for this purpose.
Table
It is mandatory to arrange a surgical table
with an adequate weight limit, and
appropriate support for body parts and
cushions for Protection from nerve injury
Strapping patient to operating table help
keep from falling off table
23. Equipment for difficult airway management ,including laryngeal
mask and fibroptic bronchoscope should be available and
surgical airways should be considered
Since mask ventilation can be difficult, a second person
It is possible that no difference between laryngoscopy and
intubation in normal and obese if paying attention for proper
patient positioning
24. Adequate pre-oxygenation is vital for obese patient
usually using 45 degree head-up
Use of 10 cm H2O CPAP during pre-oxygenation results
in high pao2 after intubation and decrease the
incidence of atelectasis
Four vital capacity breaths with 100% oxygen within
30sec have been suggested as superior to the usually
recommended 3 min of 100% oxygen in obese patient
25. Anesthetic drugs should be tailored according to their lipid
solubility and knowledge of their lingering depressive effects on
respiration calculated according to IBW or more accurately on
LBW
Lipophilic drugs (i.e. benzodiazepines, thiopental, sufentanyl)
have a greater volume of distribution and longer elimination half-life
in obese patients, although the clearance rate is similar to that
in non-obese patients
Less lipophilic drugs not affected by vd in obese
26. Drug Dosing Comments
Propofol (LBW) Preferable induction agent. Titrate dosing to effect
Thiopental TBW Increased Vd. Increased blood volume, cardiac output, and muscle mass Increased absolute
dose. Prolonged duration of action
Midazolam LBW Central Vd increases in line with body weight. Increased absolute dose. Prolonged sedation
because larger initial doses are needed to achieve adequate serum concentrations
Succinylcholine TBW Plasma cholinesterase activity increases in proportion to body weight. Increased absolute dose
Vecuronium LBW Recovery may be delayed if given according to TBW because of increased Vd and impaired
hepatic clearance
Rocuronium LBW Faster onset and longer duration of action. Pharmacokinetics and pharmacodynamics are not
altered in obese subjects
Atracurium
Cisatracurium
LBW Absolute clearance, Vd, and elimination half-life do not change. Unchanged dose per unit body
weight without prolongation of recovery because of organ- independent elimination
Fentanyl LBW Increased Vd and elimination half-time, which correlates positively with
Sufentanil LBW the degree of obesity. Distributes as extensively in excess body mass as in lean tissues. Dose
should account for total body mass.
Remifentanil IBW Systemic clearance and Vd corrected per kilogram of TBW—significantly smaller in the obese.
Pharmacokinetics are similar in obese and nonobese patients
Neostigmine LBW Reversal of muscle relaxants may be slower than in non -obese patients.
28. Any of the commonly available intravenous induction agents may
be used after taking into consideration problems pecular to individual
patients
Obese patients may require larger doses of succinylcholine
because of greater levels of pseudocholinesterase than in non-obese
patients.
Neuromuscular recovery time is similar in obese & non-obese
patient with Atracurium &CIS-ATRACURIUM (NIMBEX)
29. Bariatric procedures are usually performed laparoscopically
unless there is a contraindication such as previous extensive
abdominal surgery.
Therefore, patients are usually placed in a steep reverse
Trendelenburg position,
Although offering a slight respiratory advantage, this
position, however, exacerbates venous pooling in the limbs,
decreasing venous return and contributing to the high risk of
venous thromboembolism.
30. Pneumoperitoneum causes systemic changes during
laparoscopy. The gas most often used for this purpose is
carbon dioxide. Positioning, such as Trendelenburg, can worsen
the systemic changes of pneumoperitoneum
Systemic vascular resistance is increased with increased
intraabdominal pressure (IAP). The degree of IAP determines its
effects on venous return and myocardial performance
There is a biphasic cardiovascular response to increases in IAP.
31. Continuous infusion of short-acting ,such as propofol
or any inhalational agents or a combination may be
used to maintain anesthesia
Desflurane, sevoflurane and isoflurane are minimally
metabolized and are therefore useful agents in the obese
patient. Desflurane possibly providing better hemodynamic
stability and faster washout
32. short-acting opioids combined with a low-solubility inhalational
anesthetic, facilitate a more rapid emergence without increasing
opioid-related side effects
short-acting NDMR is a better choiced for maintenance of
anesthesia
Combined epidural and general balanced anesthesia
has been advocated to allow better titration of
anesthetic drugs, use of a larger oxygen concentration,
and optimal muscle relaxation for upper abdominal
surgery in the obese
33. VT – 10-12 mL/Kg IBW
FiO2 up to 1.0 may be needed
RR 12- 14 bpm
High PiP will be needed
PEEP = 5cm H2O or more but …
N2O is avoided
34. Fluid requirements are usually larger to prevent postoperative acute
tubular necrosis
Patients usually require up to twice the calculated maintenance fluid
requirement plus the calculated deficit based on a 12-h fasting for
the first hour by using the 4-2-1 formula
The next hour usually requires the same amount of crystalloid,
After which the amounts are reduced to approximately half the
calculated maintenance requirement, based on LBM, For the next 12
h
35. Position:
beach chair: Upper body elevated 30-45 degree.
Neuromuscular blockade : must be fully reversed and adequate muscle
strength has to be returned before patient is extubated
Oxygenation: Restoration of normal pulmonary function after abdominal
surgery may take several days.
Nasal cannula or face mask O2.
Nasal CPAP
BiPAP
Spirometry
36. Avoid IM injection
Analgesia can be provided through:
An IV opioid via PCA dosed on the basis of IBW
IV opioid
Epidural analgesia with local anesthetic or opioids
Local infiltration of the incision with local anesthetic
NSAIDs as an adjunctive to opioids and local infiltration
37. For regional anesthesia , special equipments in terms of longer
needles or special ultrasound probes may be needed
Care should be exercised in dosing
Laparoscopy can be difficult in super-morbid obese patient
Remove all endogastric tubes completely before gastric division
After RYGB pouch is created, the anesthiologist should not
blindly insert the NG tube
38. Overall, each type of surgery was safe, with the more complex
surgeries carrying a greater risk of morbidity and mortality.
Mortality ranged from a;
low of 0.1% for restrictive procedures to
1.3% for biliopancreatic diversion/duodenal switch.
Effect on co-morbidities
oDiabetes resolved in 76.8% of cases,
o lipid profiles improved in70.0%,
oHypertension resolved in 61.7%, and
o obstructive sleep apnea resolved in 85.7%.
39. Bariatric surgery is fraught with complexities that need careful consideration.
All members of the multidisciplinary team must be involved throughout all
stages of assessment, surgery, and follow up.
Weight loss surgery is associated with a decrease in obesity related co-morbidities,
which often are not seen in lifestyle changes alone.
Patients must be fully counselled on the operative and postoperative sequelae
of surgery so that they understand the risks.
Ensuring that patients are fully optimized before their surgery and receive the
appropriate levels of care during and after their operations is paramount.
