Obesity the metabolic syndrome

Obesity
and
the metabolic syndrome
Dr. Luc De Baerdemaeker
Department of Anaesthesia
University Hospital
Ghent University
Misses and mister chairmen, dear collegues,
Obesity is worldwide on the move. More and more patients undergo some form
of bariatric surgery in order to lose weight and by doing so they are trying to
reduce their morbidity and mortality caused by obesity.
Most anesthesiologists will consider morbidly obese patients as high risk. NEXT
1

Can bariatric surgery be
performed in short(er) stay ?
Why not day case surgery ?
Since this year topic is anesthesia and shorter stay the main question of this
presentation will be wether morbidly obese patients are good candidates for short
stay or why not even day case surgery and in what way can the anesthesiologist
contribute to achieve this.…
2

Outpatient laparoscopic gastric banding:
initial experience
De Waele et al. Obesity surgery 2004; 14(8): 1108-10
• BMI > 35kg/m 2 , living near hospital, adult companion
• 9 women, 1 man: mean age 36 (18-52)
mean BMI 38.4(35.1-43.3)
• ASA II
• Co-morbidities: functional dyspnea, osteoarthritis,
hypertension, type 2 diabetes, dyslipidemia
• Mean operating time 87min (65-115)
• Mean time (end surgery-discharge) 9.6 hrs
• No readmisions and no complications at 1 month
• High patient satisfaction
In recent literature, more and more publications are pointing out that this idea
might be feasible. I have picked out 2 studies.
Laparoscopic gastric banding has usually been performed on an inpatient
procedure with average hospital stays of 2-4 days.
The aim of this study from our collegues of the VUB was to assess the
feasability of LAGB as an ambulatory procedure in selected patients.
Zie tekst voor inclusie en resultaten
The conclusion was that this study demonstrates that LAGB may be performed
on ambulatory basis without complications
3

Two-day length of stay following open Roux-en-Y
gastric bypass: is it feasible, safe and reasonable ?
Stellato et al. Obesity Surgery 2004;14(1):27-34
• Retrospective study 1998-2002
• N=316, mean BMI 52.3, no differences in comorbidities or BMI
• Discharge criteria included oral intake, pain control, written test for
understanding of the operation
• Operative time 1998: 241 min
2002: 156 min
• Discharge at 2 days 1998: 0%
1999: 0%
2000: 2%
2001: 15%
2002: 50% with 4.1% 30-d readmission
• Multidisciplinary approach since 2001
• Aggressive preoperative education and screening has to be performed
This is a retrospective study performed at the university hospitals of cleveland.
316 patient underwent open roux en y gastric bypass in this period. Important to
notice is the start of a multidisciplinary approach in 2001 and the decline in
operating time. The conclusion was that discharge at day 2 can be safe provided
that agressive preoperative education and screening is performed.
4

6 Predictors of prolonged hospital stay in
open and laparoscopic gastric bypass
• Open surgery
• High BMI
• Increasing length of surgery
• Sleep apnea disorders
• Asthma
• hypercholesterolemia
Ballantyne et al. Obesity surgery 2004;14(8):1042-50
The authors of this retrospective study of 311 patients performed at the bariatric
surgery center somewhere in the USA,
Managed to identify 6 predictors of increased length of stay following open or
laparoscopic roux en y gastric bypass.
5

Patients with the greatest odds for
longer stay
• Men with sleep apnea 5.54 OR
• Men with the metabolic syndrome 6.67-10.2 OR
• Women with asthma 3.73 OR
• Women with coronary artery disease 8.65 OR
• Laparoscopy in patients with
Sleep apnea
11.53 OR
• Laparoscopy in patients with
coronary artery disease
12.15 OR
Ballantyne et al. Obesity surgery 2004;14(8):1042-50
Subset analysis identified patients with the greatest odds of longer hospital stay.
6

The metabolic syndrome
The deadly quartet
• Constellation of abdominal obesity
• Hypertension
• Diabetes
• Dyslipidemia
Clinical implications:
• Increased risk of coronary artery disease
• Increased risk of non-alcoholic steatotic hepatitis
(NASH)
The constellation of abdominal obesity, hypertension, diabetes and dyslipidemia
has been called the metabolic syndrome, syndrome X, the deadly quartet, the
insulin resistance syndrome, and the obesity dyslipidemia syndrome. The clinical
implications are that individualsz with the metabolic syndrome have an increase
risk of coronary artery disease and the development of non alcoholic steatotic
hepatitis NASH
7

Are obese patients at higher risk of
surgical and post-operative
complications ?
• Obese do have more wound infections
• The regressive attitude in referring
morbidly obese patients for surgery or
denying surgery to such patients should be
reconsidered
Dindo et al. The Lancet vol 361.june 14,2003:2032-35
This article in the lancet compared the overall mortality and morbidity after
surgery between obese and lean patients and found as a major conclusion that
wound infection are more frequent in the obese probably due to altered
microcirculation but compared to lean patietns post operative complications were
simular. So this report seems to confirm the findings in the previous studies. The
author clearly states that it is time the mecdical world changes its attitude towards
these patients.And I quote literally: the …….
8

Is extensive preoperative testing
necessary in morbidly obese
patients?
• Apparently not
Ramaswary et al. Journal of gastrointestinal surgery 2004;8(2):159-165
Routine tests: Complete blood count
Electrolytes
ECG
Anemia studies
For selected patients: coagulation testing
chest X-ray
cardiac stress tests
pulmonary function tests
Screening obese patients is important but how far do we have to go ? According
to this study not that far.
9

Is extensive preoperative testing necessary in
morbidly obese patients?
Ramaswary et al. Journal of gastrointestinal surgery 2004;8(2):159-165
Chest X-ray 4% abnormal
ECG
15% abnormal
Spirometry 21% abnormal
Asthma and high BMI predictive factors
Echocardiography 2 % abnormal
previous cardiac disease predictive factor
No intervention needed
. Full screening consisted of chest X ray, pulmonary fuction testing, ECG and
dobutamine stress test. Blood work included ABG, Blood count, thyroid function
tests and anemia studies on iron and vit B12.
10

Circulation 2002;105:1257-67
In 2OO2, The american heart assoaciates updated their guidelines for the
perioperative evulaation of cardiovascular risk for non-cardiac surgery. Time is
to limited to go through all the details.
11

But took a look at the major clinical predictors of cardiovascular risk and you
will see that obesity is not one of them.
12

In the surgical procedures as risk predictor the only hint we get is in the
intermediate and low risk indicators
13

But the american heart association did stress out on the functional capacity of the
patietn expressed as METABOLIC EQUIVALENTS.
IN their flow chart any patient with a score less then 4 MET is to be considered
high risk and should could a cardiac work out.
14

The New England Journal of Medicine 1999 ;340: 937-944
Current Concepts: Preoperative Pulmonary Evaluation
Gerald W. Smetana
Factors contributing to respiratory complications
– patient related Smoking
poor exercise capacity
general health status
COPD / Asthma
– procedure related distance from diaphragm
> 3 hours surgery
Locoregional anaesthesia
use of long acting muscle relaxant
NO OBESITY !
The same can be applied to spirometry.
15

The New England Journal of Medicine 1999 ;340: 937-944
Current Concepts: Preoperative Pulmonary Evaluation
Gerald W. Smetana
Pre-operative pulmonary-function testing
• spirometry has a variable predictive value, remains controversial
• Clinical findings are more predictive then spirometry
Odds Ratio of 5.8 vs. 1.0
• PaCO 2 > 45 mmHg is a strong risk factor
Criteria
• FEV 1 < 70% predicted value
• FVC < 70% predicted value
• FEV 1 /FVC < 65%
Increased risk for
pulmonary complications
16

The New England Journal of Medicine 1999 ;340: 937-944
Current Concepts: Preoperative Pulmonary Evaluation
Gerald W. Smetana
Who should get a spirometry ?
• Patients undergoing thoracic or upper abdominal
surgery with unexplained symptoms of:
– cough
– dyspnea
– exercise intolerance
• COPD / Asthma
17

The New England Journal of Medicine 1999 ;340: 937-944
Risk-reduction strategies
Preoperative stop smoking > 8 weeks
treat airflow obstruction
treat respiratory infection and delay surgery
educate patient regarding lung expansion
intraoperative < 3 hrs surgery
locoregional anesthesia
avoid pancuronium
laparoscopic procedures when possible
postoperative deep breathing exercises or incentive spirometry
CPAP
epidural analgesia
18

Patient selection in ambulatory anesthesia
an evidence based review part 1-2
Bryson et al; CAN J ANESTH 2004;51:768-94
• OSAS: wear nasal CPAP
non opioid analgesia, avoid opioids
• Morbid obesity:
respiratory risks have to be recognized and
managed
• Diabetes:
metformin withdraw not supported by evidence
tighter perioperative glucose control
half dose adminstered as intermediate duration insulin
You might have noticed that most studies so far were publishid in surgery
journals. This very recent publication evaluates the managment of patients with
selected medical conditions undergoing ambulatory anesthesia and surgery.
19

Pre-op evaluation
• Careful history taking and physical examination
• look for signs of symptoms of sleep apnea
difficult intubation
Mallampati score
Neck circumference > 40
Short thyromental distance
hypognathia
upper lip bite test
20

Upper lip bite test
2003;96:595-99
from Kahn et al. AA
21

Upper lip bite test
2003;96:595-99
from Kahn et al. AA
22

Symptoms of sleep apnea
• Presence of loud, habitual snoaring
• episodes of apnea witnessed by a bed partner
• episodes of nocturnal choking or gasping
• daytime hypersomnolence
Known associations:
•BMI > 30
• Orofacial or pharyngeal abnormalities
23

RESPONSE TO CO 2
• OSAS: OBSTRUCTIVE SLEEP APNEA SYNDROME
30 apneic periods > 20 sec over 7 hours
• OHS: OBESITY HYPOVENTILATION SYNDROME
OSAS + hypoxemia
hypercapnia
pulmonary hypertension
hypersomnolence
• PICKWICKIAN SYNDROME: described in 1837 by CH.
Dickens
OHS +
polycythemia
biventricular failure
24

OSAS
• Incidence in obese women 3-25%
obese men 40-78%
• Caused by
abundant peripharyngeal adipose tissue
abnormal upper airway tone during
REM sleep
25

Why is detection of OSAS
important?
• OSA patients are more sensitive to the
depressant effects of hypnotics and opioids
• OSA is associated with difficult
laryngoscopy and difficult mask ventilation
26

Detection of OSAS
• Polysomnographic testing in sleep lab
• (not reliable) predictive tools
–History
– Systemic hypertension
– Neck circumference > 40 cm
– Malampatti score 3-4, hypognathia, short
thyromental distance
27

OSAS: PACU or ICU ?
28

conclusion
• Bariatric surgery can be performed in
short(er) stay and sometimes day case
• Extensive preoperative testing is not
necessary
• But patient selection is important
• But nobody mentioned anesthesia
technique!!!
29

Risk of morbidly obesity
• Aspiration of gastric content
• difficult intubation
• sleep apnea
• co morbidity
• respiratory complications
• right heart failure
• anatomic considerations
• farmacological considerations
30

Pathophysiology
Haemodynamic changes
• Pre-afterload
• MPAP
• RVSW,LVSW
• Cardiac diameter
• CO
• SV
• Left ventricular function
• arterial hypertension +
The cardiac diameter is usually 20-55% increased, autopsy studies demonstrate
ventricular hypertrophia and increased cardiac weight.
Increased CO is Due to A Incresed SV; CO is correlated to weight and
proportional to the increased oxygen consumtion in morbid obesity.
Agarwal et al. Found that left ventricular function in asymptomatic morbidly
obese patients was 57% of normal values. De Divitiis et all published in
Circulation 198O a report of depressed left and right ventricular function
assessed by left and right catheterisation in relatively young asymptomatic obese
patients.
Hypertension coorelates well with obesity. Probably due to the fact that the high
CO is forced into an arterial system with unaltered SVR.
The Framingham study showed a positive correlation between £Angina pectoris,
sudden death and obesity but not with AMI.
31

Obesity and heart failure
Kenchaiah et al.N.Engl.J.Med.2002Vol.347,n°5: 305-13
32

Pathophysiology
Respiratory changes
PULMONARY
MECHANICAL
• chestwall compliance
• lung compliance
• total resp. compliance
• FRC due to ERV
• FRC decreases from
standing to Trendlenburg
• Danger zone: FRC = CV
airway closure
. .
V/Q mismatch
The respiratory changes can be differentiated in mechanical and pulmonary
changes
The decrease in chest wall compliance is caused by the fat accumulation around
the ribs, diaphragm and intra abdominal cavity.
The increased pulmonary blood volume is responsible for the decrease in lung
compliance.
Both result in a decrease of total respiratory compliance.
The FRC is decreased due to a decreased ERV. Why is FRC so important to the
Anaesthesiologist? First off all, By refreshing the FRC with 100% Oxygen, we
can give the patient an oxygen reservoir,necessary to maintain adequat
oxygenation during the induction apnea. Secondly, IF the FRC decreases further
to the point of µClosing volume, more and more airway collaps will occur in
depentdent lung regions, giving rise to further ventilation/ perfusion mismatch,
shunting in other words. The result will be a negative effect an arterial pO2.
It is important to point out that bringing the patient in a supine or Trendlenburg
position will cause a further decrease in FRC.
33

Morbid Obesity and Postoperative Pulmonary Atelectasis: An
Underestimated Problem
A.- S. Eichenberger et al.
Anesth Analg 2002;95:1788-92
MO patients will develop much more atelectasis, which will persist and even tend to increase,
24 hours after tracheal extubation
34

How to get rid of atelectasis
• pre-oxygenation with FIO 2 0.8 ??
• Pre-oxygenation with CPAP (5 min) and even
application of PCV (< 20 cm H 2 O) and PEEP (5
min) via a face mask during induction
• Before extubation: vital capacity manoever and
avoiding FIO 2 of 1.0 !!
• PEEP during surgery
• post-op: sitting position
CPAP or BIPAP
35

1.00 or 0.8 FIO 2 for induction ?
36

CPAP at induction
CF 800
Continuous flow CPAP system for a wide application
range. Bellow reservoir ensures an effective therapy
with constant pressure at a small flow.
37

CPAP and mask ventilation during induction
Prevention of atelectasis formation during the induction of general
anesthesia in morbidly obese patients
Coussa et al Anesth Analg 2004;98:1491-5
VCV: Vt 10ml/kg IBW freq 10/min
38

CPAP and mask ventilation during induction
Prevention of atelectasis formation during the induction of general
anesthesia in morbidly obese patients
Coussa et al Anesth Analg 2004;98:1491-5
CPAP 0 cmH 2 O
and PEEP 0 cmH 2 O
CPAP 10 cmH 2 O
and PEEP 10 cmH 2 O
39

Mechanical Versus Manual Ventilation via a Face Mask During the
Induction of Anesthesia: A Prospective, Randomized, Crossover
Study
Achim von Goedecke et al. Anasth Analg 2004;98:260-3
Hemodynamic and Respiratory Characteristics in 41 Patients During
Pressure-Controlled Ventilation (PCV) and Circle System Ventilation (CSV)
Variable PCV CSV P value
Heart rate (bpm) 69 ± 13 70 ± 11 NS
Mean arterial blood pressure (mm Hg) 78 ± 8 78 ± 11 NS
Oxygen saturation (%) 98 ± 1 98 ± 1 NS
End-tidal carbon dioxide (mm Hg) 34 ± 3 33 ± 4 NS
Respiratory rate (breaths/min) 15 ± 0 15.4 ± 1 0.015
Expiratory tidal volume (mL) 650 ± 100 680 ± 100 0.001
Minute ventilation (L/min) 10.4 ± 1.8 11.6 ± 1.8

Extubation on 100% oxygen ?
The Effect of Increased FIO 2 Before Tracheal Extubation on
Postoperative Atelectasis
Benoît et al. Anesth Analg 2002;96:1777-81
FIO 2 100 with and
without VCM
FIO 2 0.4 + VCM
VCM= manual inflation of the intubated patient’s lungs to 40 cm H 2 Ofor15 s
41

Does PEEP make sense ?
It sure does !
5-8 cm H 2 O
42

Should obese patients be considered as
non fasting ?
Risk factors for aspiration of gastric content in Obese
• abnormal gastric emptying
• large gastric content after fasting ??
• low gastric pH (< 2.5)
• increased abdominal pressure
• lower oesopohageal sfincter pressure
• association of obesity and gastro-oesophageal reflux
• Increased prevalence of hiatal hernias in the obese
43

What about Gastric aspiration
risk AFTER bariatric surgery ??
• REDO gastric banding or slippage of band
!!
• Gastric emptying for solid food is delayed
• Differential effects of bariatric procedures
on gastric emptying
• Gastric emptying patterns change over time
as patients lose weight
Patients having undergone gastric reduction have an spiration risk that is not very
well understood. Studies with Radionuclide labeled material showed that gastric
emptying of solid food is delayed up to 3 month after surgery. After 12 months
emptying was faster the pre surgery values. But different barriatric procedures
have differentioal effects on gastric pouch emptying. Surgery with truncal
vagotomy will reduce the acitdity of the gastric contetn but will also stimulate
bacterial overgrowth and decrease the mobility of the stomach. As patients start
to loose weight, their gastric emptying pattern also changes!!
Patients with Redo gastric banding or slippage of the band usually have a dilated
or decompensated oesophagus filled with food residuesand definetely pose a high
risk of aspiration.
44

Haemodynamic problems during
laparoscopy
•SVR
•MAP
• Myocardial filling pressures
• CI up to 50%
•HR =
Joris et al. Anesthesia Analgesia 1994;76:1067
changes are phasic
45

Factors influencing Haemodynamic respons
during laparoscopy
• Intra-abdominal pressure > 12 mmHg
• patient position
• CO 2 absorption
• ventilatory strategy
• surgical technique
• intravascular volume
• pre-existing cardiopulmonary status
• neurohormonal factors
• medication and anaesthetics
46

Regional circulatory Changes
• Cerebral ICP CBF
• liver flows
•Bowel pHi splanchnic perfusion
• Kidney arterial-, venous-,cortical flow
> 15 mmHg IAP, use of warm CO 2
• lower limbs venous flow
IMPACT in critically ill patients !
47

Dumont;Mattys;Mardirosoff;Picard Obesity Surgery 1997; 7:326-331
Hemodynamic Changes During Laparoscopic Gastroplasty in
Morbidly Obese Patients
Laparoscopic procedures are safe
for Morbidly Obese Patients
48

Pre medication
• Short acting Benzodiazepine
e.g. midazolam, lorazepam
•H 2 antagonist e.g.
ranitidine 150 mg PO or 50 mg IV
1hr before surgery
49

PHARMACOKINETICS
PHARMACODYNAMICS
• WATER-SOLUBLE COMPOUNDS: V d =, CL =
• LIPOPHILIC DRUGS V d
• PHASE 1 METABOLISM ( ox, red ): =
• PHASE 2 CONJUGATION PATH: incr
• BENZODIAZEP., THIOPENTAL: V d incr, Cl =, T 1/2
• PROPOFOL: bolus dose on IBW
infusion: V d =, Cl =, T 1/2 =
• FENT: V d =, Cl =, SUF: V d incr, CL =, ALFENT: V d =, Cl
• SUCCINYLCHOLIN:
1.5 mg/kg
• MIVACURIUM, ATRACURIUM: recovery =
• PANCURONIUM, VECURONIUM: recovery
50

Pharmacology
•Use the Ideal Body Weight (IBW) !
• How to calculate IBW ?
– from nomograms e.g. metropolitan life insurance
– MEN Bodylength cm - 100 = IBW kg
WOMEN Bodylength cm - 105 = IBW kg
• Succinylcholine: dosage on real body mass
The problem of pharmacokinetics and dynamics can be easily solved. For the
major anaesthetic agents, the pharmacokinetics in morbid obees patients
resemble those of lean persons if the LBM is used. This goes for the major
hypnotic agents, the opioids and the muscle relaxants. There is one exception in
the form off succinylcholine, here the real body mass has to be used to calculate
the dosage.
There are many rules and formulas to calculate the LBM, but this rule is the most
easy one in my experience.
51

Does size matter?
Buoillon T., Shafer SL.
Anesthesiology 1998;89(3):557-60
52

propofol
thiopental
midazolam
Vecuronium
Atracurium
Cisatracurium
Rocuronium
Succinylcholine
Mivacurium
neostigmine
alfentanil
sufentanil
remifentanil
Induction IBW
Maintenance TBW or
IBW+0.4 x excess weight
7.5 mg/kg IBW
TBW
TBW for initial dose
IBW for continuous dose
IBW
TBW
Initial dose .15 mg/kg – 2.3mg/10kg>70kg
Supplemental dose .15mg/kg – 0.7mg/10kg>70kg
TBW
IBW
IBW
TBW
>140 kg: max of 120-140mg
TBW
TBW
IBW
IBW+0.4 x excess weight
TBW
TBW
IBW+0.4 x excess weight if BMI>40
IBW
Kirby,Redfern,Gepts
Servin
Gepts
Buckley
Jung
Greenblatt
Reves
Schwartz
Varin, Weistein
Kirkegaard nielsen
Schmith,Kisor
Leykin
Puhringer, Leykin
Bentley,Rose
Cooper, Brodsky
Pino, Patel
Kirkegaard-Nielsen
Bentley
Salihoglu
Maître
Schwartz,Gepts
Schlepchenko
Minto, Egan
53

Juvin et al. Anesthesia Analgesia 2000;91:714-9
Postoperative Recovery After Desflurane, Propofol
or Isoflurane Anesthesia Among Morbidly Obese
Patients: A Prospective, Randomized Study
Advantage of desflurane
– predictable and rapid recovery
– reduction in postoperative hypoxemia
– increase in patient mobility
54

Application of TCI models in the obese
PROPOFOL
• Propofol does not accumulate in morbidly obese patients.
Maintenance dosage is the same as in normal patients
Servin et al Anesthesiology 1993;78(4):657-65
• Marsh kinetics ( diprifusor®) was not developped
for morbidly obese
use corrected body weight
corrected body weight = IBW +( 0.4 x excess weight)
• Schnider and Minto’s model for propofol uses weight,
height and lean body mass as covariates with improvement
Schnider et al Anesthesiology 1998;88(5):1170-82
Primea-base, Fresenius®
55

Application of TCI models in the obese
REMIFENTANIL /SUFENTANIL
• Minto-schnider kinetics for remifentanil correct for lean body mass
Egan et al Anesthesiology 1998;89(3):562-73
• Gepts kinetics for sufentanil predict with accuracy the plasma
concentration in obese patients
Slepchenko et al Anesthesiology 2003;978(1): 65-73
56

WARNING
Difficult intubation ahead !
• Orotracheal tube mounted with guide wire
• ALWAYS have Difficult intubation material
stand by at moment of induction
• remember the algorithm for difficult intubation
• consider awake intubation
neck circumference of 60 cm = 35 % change of
difficult intubation
57

The Intubating Pillow
“Stacking”
From James M. Rich
AA 2004;98:264-65
Letter to the Editor
59

Positioning the Patient
•Obese are more prone to nerve injury
• avoid unphysiological flexion of the head
• upper limb: ulnar nerve: suppination
N. Axillaris: humerus horizontal
• sitting piece supports gluteus
• lower limb: padded leg support
N. Fibularis
60

Monitoring
•ECG
• Pulse oxymetry
• invasive bloodpressure monitoring (ASA)
• non-invasive bloodpressure with correct cuff
• capnography
• spirometry
• BIS monitoring
61

Role of BIS
• Decreasing recovery times
• reducing anaesthetic consumption
• decrease in PONV
• better controllability of anaesthesia
62

PONV
• PONV after volatiles: still controversial
• Propofol and the BIS guided volatiles:
Benificial influence ?
- Juvin P., Vadam C. , Malek L., Dupont H., Marmuse JP., Desmonts
JM.: Postoperative Recovery After Desflurane, Propofol, or Isoflurane
Anesthesia Among Morbidly Obese Patients: A Prospective,
Randomized Study. Anesth Analg 2000; 91: 714-9
- Nelskylä KA. , Yli-Hankala AM;, Puro PH., Kortilla KT.: Sevoflurane
Titration Using Bispectral Index Decreases Postoperative Vomiting in
Phase II Recovery After Ambulatory Surgery. Anesth Analg 2001; 93:
1165-69
63

Pain management
• During anesthesia Propacetamol 2-4g IV
Diclofenac 150 mg IV
infiltration of trocar site
• postoperative propacetamol 2g/6h IV
piritramide 20mg IM q6hr
• IV PCA with morphine: use IBW
64

A Non-opioid drug combination
for analgesia
• Ketorolac 30 mg iv, at beginning and end
• Clonidine 300-500µg iv within first hour
• Lidocaine 100mg bolus iv at induction, followed by
4mg.min -1 first hour, 3mg.min -1 for the second hour,
2mg.min -1 until end.
• Ketamine 0.17- 1 mg.kg -1 .hr -1 iv during maintenance
• Magnesium sulphate 80mg.kg -1 iv total dose given
during maintenance
• Methylprednisolone 60 mg iv bolus in bedhold
Feld et al.Non-opioid analgesia improves pain relief and decreases
sedation after gastric bypass surgery. Can J Anesth 2003;50(4):336-41
Obese patients may be sensitive to the respiratory depressant effects of opioid
analgesic drugs and are more likely to require postoperative ventilation to avoid
hypoxic episodes. Especially patients with sleep apnea disorders are a relative
contraindication for the use of patient controlled analgesia ( Van Dercar DH et al
Anesthesiology 1991;74: 623-4) Several non opioid drugs have all been shown to
be analgesic. Combining these drugs may potentiate analgesic effects by
multimodel appraoch to pain relief and by lowering the effective dose for each
drug (decreasing side effects at the same time) Feld and coworkers compared a
sevoflurane-fentanyl based anesthesia in morbidly obese patients with a
sevoflurane-non opioid combination. Results showed that the non opiod
treatment produced analgesia with stable blood pressure and heart rate durning
surgery and a rapid recovery. Fentanyl anesthesia may produce postoperative
hyperalgesia and reduce the effectiveness of post-operative morphine
administration.
65

REGIONAL ANESTHESIA
• TECHNICALLY DIFFICULT: easier in sitting position
• DOSE: SUBAR, EPID: 75-80% of normal: controversial
• BLOCKADE at T 5 : minimal change from baseline
• BLOCKADE above T 5 : resp. and cardiovasc. compromise
• EPID AN. IN COMBINATION WITH LIGHT GEN ANESTHESIA
reduction volatile anesthetics
no need for neurom. blocking drugs
rapid postop. mobilization
shunt , LV work , A-VDO 2 , VO 2
• POSTOP EPIDURAL ANALGESIA
dose local anesthetics and opioids: =
66

PACU
• Maintaining semi sitting position
• oxygenmask when necessarry
• DVT profylaxis
• chest fysiotherapy when necessarry
• PONV treatment
• CPAP or BIPAP
• consider non invasive ventilation
67

Does size matter?
68

Pharmacological treatment of eating
disorders: interactions with anesthetics
• Antidepressants
Selective serotonin Reuptake Inhibitors
fluoxetine, fluvoxamine,sertraline, citalopram sibutramine,
cardiovascular depressants hypotension
• anti-obesity agents
Phentermine-fenfluramine
orlistat lipase inhibitor xenecal
• anticonvulsants
topiramate
• cannabinoid receptor antagonist
rimonabant
70