BARIATRIC SURGERY
The BIGGA issue: Surgery and the obese patient
Are anaesthesia services following best practice when it comes to managing obese patients and are theatre teams aware of important guidance, designed to ensure safer care?
UK hospitals are still unaware of best practice guidelines relating to anaesthesia in obese patients, yet there is an increased risk of complications in this patient group. According to the latest NHS figures, 26% of adults are classified as obese – with a BMI of 30kg/m2 or higher.1
As a nation we are
getting bigger, which is presenting challenges for theatre teams across the country.
Obese patients are at greater risk of complications during – or after – an operation if they suffer from obesity- related diseases, such as high blood pressure, diabetes, obstructive sleep apnoea, a history of deep vein thrombosis (DVT) and angina. The Society for Obesity and Bariatric Surgery (SOBA) warns that, after an operation, these patients are more likely to experience chest infections and difficulty breathing, wound infections, poor wound healing, and DVT. However, patients with centrally
distributed fat (ie: ‘apple shaped’ as opposed to ‘pear shaped’) are at greater peri-operative risk than those with peripherally distributed fat. This is because they are more likely to exhibit metabolic syndrome, which consists of central obesity, hypertension, insulin resistance and hypercholesterolemia.2 Heavier patients undergoing surgery, presenting with this added risk factor, therefore require careful pre-operative evaluation for comorbidities. In addition, there needs to be special consideration of potential issues around airway management, positioning on the theatre table, pressure relief, patient monitoring technology and anaesthetic techniques.3 There are many reasons why obese
patients require special management when undergoing surgery. For example, severe obstructive sleep apnoea occurs in 10 to 20% of patients with BMI > 35 kg.m2
and is often undiagnosed. The guideline, Peri-operative management
of the obese surgical patient (2015) explains that diagnosis of obstructive sleep apnoea is associated with: “a greater than doubling of the incidence of postoperative desaturation, respiratory failure, postoperative cardiac events and ICU admission.”2 SOBA also explains in its consensus statement4
that the morbidly obese
have a reduced functional residual capacity and an increased basal oxygen utilisation. Therefore, once they become apnoeic, they experience rapid and early desaturation. Pre-oxygenation is essential, therefore, including in the head-up or ramped position. Recovery from anaesthesia is also frequently prolonged in obese patients and they are at increased risk of aspiration and acute upper airway obstruction following tracheal extubation.4 Safe surgery for obese patients
requires a variety of specialist equipment – such as suitable trolley/operating tables and table extensions; gel padding; difficult airway equipment; a hover mattress or equivalent; a ramping device (to correctly position the patient); longer spinal, regional and vascular needles, along with ultrasound equipment; and, of course, enough staff to move the patient. The full list of suggested equipment can be viewed via the SOBA Single Sheet Guideline.3
NICE has also published guidance on technology such as electroencephalography (EEG)-based depth of anaesthesia monitors. Patients who are considered at higher risk of excessively deep levels of anaesthesia include patients with a high BMI and patients with poor cardiovascular function.
The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia (AAGA) also
OPERATING THEATRE l JULY 2018 l 25
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