OBESITY
Physiology and Classification
Avoid operating as day cases
Medical Risks
 Weight gain of 5-9kgs increases risk of developing Type 2 diabetes to 2x that of
individuals who have not gained weight
 >80% of diabetics are overweight or obese
 Incidence of heart disease (IHD, CCF, sudden cardiac death, abnormal heart
rhythm) is increased in people with BMI>25
 Hypertension is 2x as common in obese than those at a normal weight
 For every 1kg increase in weight, risk of arthritis is increased by 9-13%.
Surgical Risks
 Associated with
1. Cardiac disease
 Morbid obesity is often associated with left ventricular enlargement and
both systolic and diastolic dysfunction, even in patients without overt
cardiac disease
 risk of atrial fibrillation increases 50% in the obese population
2. Hypertension
3. Asthma
4. Obstructive sleep apnoea
 Pulmonary hypertension
5. Metabiolic disturbances
 diabetes
6. Psychological issues
Anaesthesia
1. venous access
2. positioning
 more prone to nerve compression on the table
 rhabdomyolysis and renal failure from gluteal necrosis reported
3. airway control
 GI reflux
4. intubation
 more likely to need endotracheal intubation
5. ventilation
6. pharmacology – volume distribution of drugs
Nosocomial Infection
 Studies from cardiothoracics and General Surgery
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3x increase risk in obese
4x increase risk in severe obese
Mostly due to increase in surgical site infection (2-3x RR)
Mechanisms
1. decreased oxygen tension
2. immune impairment
3. tension and secondary ischemia along long suture lines.
4. chronic skin infections ie Candida
 Also increase risk of pneumonia and UTI
Poor wound healing
 Due to
1. infection
2. wound tension
3. reduced oxygen tension
Pulmonary
 Restrictive lung pattern
 Increased atelactasis
Gastric
 Delayed gastric emptying – in general have higher preoperative gastric volumes
 Reflux
Venous Thromboembolism
 Mechanisms
1. increased intra-abdominal pressure
2. venous stasis
3. hypercoagulable state
• higher levels of factor VIII and factor IX, but not of fibrinogen )
• decreased circulating antithrombin III (AT III) and decreased
fibrinolytic activity
4. Poor mobility
 estimated incidence of DVT and PE in patients receiving perioperative prophylaxis
ranges from 0.2% to 2.4
 Relative risk (obese vs nonobese) Am J Med 2004
• DVT – 2.5x
• PE – 2.2x
 In overweight/obese (BMI>25) women on OCP – 10x risk of DVT (Thromb
Haemost 2003)
Blood Loss
 BMI correlated with increased surgical blood loss
Risks in Plastic Surgery
Breast Reconstruction
Paige, Bostwick PRS 1998
 Pedicled TRAM, retrospective n=257
 Obesity significantly associated with
1. Donor site complications
2. Fat necrosis
3. Partial flap loss
4. Breast mound infection
Chang DW; Effect of Obesity on Flap and Donor site complications in Free TRAM
PRS 2000 Apr
 Free TRAM, retrospective n=939 flaps (718 patients)
 Flap complications: Obese(BMI>30) vs normal weight
o overall flap complications (39.1 vs 20.4%),
o total flap loss (3.2 versus 0%)
o flap seroma (10.9 versus 3.2%)
o mastectomy flap necrosis (21.9 versus 6.6%).
 Flap complications: Overweight(BMI 25-30) vs normal weight
o overall flap complications (27.8 versus 20.4%)
o total flap loss (1.9 versus 0%)
o flap hematoma (0 versus 3.2%)
o mastectomy flap necrosis (15.1 versus 6.6%)
 Donor complications: Obese vs normal weight
o overall donor-site complications (23.4 versus 11.1%)
o infection (4.7 versus 0.5%)
o seroma (9.4 versus 0.9%)
o hernia (6.3 versus 1.6%).
 Donor complications: Overweight vs normal weight
o overall donor-site complications (19.8 versus 11.1)
o infection (2.4 versus 0.5%)
o bulge (5.2 versus 1.8%)
o hernia (4.3 versus 1.6%)
Alderman AK, Wilkins EG, Kim HM, Lowery JC. Complications in postmastectomy
breast reconstruction: two-year results of the Michigan Breast Reconstruction
Outcome Study. Plast Reconstr Surg. 2002 Jun
 prospective cohort design, women undergoing first-time, immediate or delayed
breast reconstruction
 326 patients from 12 centres
 increasing body mass index was found to be associated with increasing odds of a
complication, with an odds ratio of 1.08 for total complications and 1.12 for major
complications.
Munhoz AM; Outcome analysis of breast-conservation surgery and immediate
latissimus dorsi flap reconstruction in patients with T1 to T2 breast cancer. Plast
Reconstr Surg. 2005 Sep
 BMI>30 associated with increased donor site complications; especially seroma (a
5.2-fold increase)
Ducic I, Spear SL; Safety and risk factors for breast reconstruction with pedicled
transverse rectus abdominis musculocutaneous flaps: a 10-year analysis. Ann Plast
Surg. 2005 Dec
 Retrospective study of 224 pedicled TRAM recons
 Obesity (BMI>30) related to
 Overall donor site complications (OR 2.6)
 Overall flap complications (OR 2.6)
 Multiple flap complications (OR 6.7)
 TRAM delayed healing (OR 4.2)
 Minor flap necrosis (OR 5.1)
Wang HT, Hartzell T, Olbrich KC, Erdmann D, Georgiade GS; Delay of transverse
rectus abdominis myocutaneous flap reconstruction improves flap reliability in the
obese patient. Plast Reconstr Surg. 2005 Aug;
 By delaying the pedicled TRAM, flap related complications did not show an
increase with increasing BMI
 However non-flap-related complications, such as deep venous
thrombosis/pulmonary embolism; donor site morbidity , was 8% for those with a
body mass index of less than 30 vs 32% for those with an index greater than 30.
Summary
1. increased risk of flap failure and flap complications - seroma
2. increased risk of mastectomy flap complications
3. increased risk of donor site complications especially seroma, wound healing, and
infection
Breast Reduction
 Only 20% of women undergoing reduction mammoplasty are of normal weight
Strombeck 1964
 systemic and local complications
 4.4% for the nonobese
 13.5% for those > 10 kg overweight.
Zubowski (PRS 2000; retrospective n=395)
 Major local complications (skin loss, nipple loss, abscess, and hematoma )
 6.2% for the nonobese
 9.2% for those > 10 kg overweight.
 Complications correlated with increasing weight of reduction
Platt (Ann Plast Surg 2003 prospective n=30)
 BMI > 26.3, 33% wound breakdown rate
 BMI < 26.3, 10% wound breakdown rate; P < 0.05
Wagner (PRS 2005, retrospective n=186)
no increase in the complication rate in the obese patients
O’Grady (PRS 2005, retrospective n=133)
 BMI not associated with nipple necrosis, hematoma formation, fat necrosis, cyst
formation, nipple sensation, or hypertrophic scarring
 Higher BMI predicted a delayed healing, wound dehiscence, and infection.
(relative risk 1.2x)
Summary
increased risk (1.5-3x) of:
1. delayed healing
2. wound dehiscence
3. infection
Stronger correlation with size of reduction
Abdominoplasty
Vastine (Ann Plast Surg 1999)
 Retrospective study, n=90
 80% of obese patients had complications compared with the borderline and
nonobese patients, who had complication rates of 33% and 32.5% respectively
 Previous gastric bypass surgery had no significant effect on the incidence of
postabdominoplasty complications.
van Uchelen JH, Werker PM, Kon M. Complications of abdominoplasty in 86
patients. Plast Reconstr Surg. 2001 Jun
 Increased incidence of wound complications
Kim J, Stevenson TR. Abdominoplasty, liposuction of the flanks, and obesity:
analyzing risk factors for seroma formation. Plast Reconstr Surg. 2006 Mar;
 atients who are overweight or obese present a statistically significantly higher
risk for developing seromas postoperatively than patients of normal weight.
 Liposuction of the flanks in concert with abdominoplasty did not increase the risk
of seroma formation.
Summary
 Increased risk of infection, delayed wound healing and seroma
Body contouring
Taylor (Obese Surg 2004)
 Retrospective study, n=30 post massive weight loss
 Overall morbidity 42%
 20% wound breakdown
 17% seroma
 1 patient died from PE
 Challenging surgery requiring individualized approaches with intensive follow-up.
Sanger (Ann Plast Surg 2006)
 Retrospective study, n=26 post massive weight loss
 27% wound complications(seromas, hematoma, infection, and fat necrosis)
 increase in wound complications attributed to the inherent complications seen with
obese patients.
Summary
 Only case series in the literature
 High complication rates 30-40%