Explainers

Considering the Larger Patient in the Operating Theatre – What do You Need to be Aware of?


Obesity is not only a growing epidemic in the general population with ‘a staggering 63.4 percent of Australian adults overweight or obese’ (Leigh Campbell, 2016) – it’s increasingly becoming an issue within perioperative practice.

Whilst there is often a BMI limit for day case surgery and minor procedures, the fact remains that on the whole our patients are getting larger across all surgical disciplines, and there are extra considerations we need to be aware of within the operating theatre department.

Although BMI is not an ideal measure of risk, it is the most useful of the currently available markers and is a simple measure to apply (The Association of Anaesthetists in Great Britain and Ireland, 2007). However, it shouldn’t be used as a sole indicator of surgical suitability – or risk.

Pre-Operative Assessment

Where possible, a thorough pre-operative assessment is crucial to not only establish size and weight of the patient to enable the relevant equipment and precautions to be put in place, but to also establish:

  • Airway limitations
  • Bruising and pressure injury risk
  • Joint and mobility issues
  • Obstructive sleep apnoea – a strong indicator of airway complications
  • Underlying heart disease and associated co-morbidities, such as hypertension; and
  • Diabetes and insulin resistance.

Early communication between the multi-disciplinary team involved with caring for the obese patient is essential. One aspect of the pre-operative assessment is using the acquired information to schedule the surgery for when there is sufficient personnel, resources and additional time available (The Association of Anaesthetists in Great Britain and Ireland, 2007). This includes post-operative care on the ward.

Obese patients are at greater risk of difficult intubation, defined by the American Society of Anaesthesiologists taskforce as ‘the clinical situation in which a conventionally trained anaesthetist experiences problems with mask ventilation or tracheal intubation or both’ (1993).

Along with a BMI greater than 30 and a Mallampati score of 3 or 4 being indicative of a difficult airway, neck circumference has also been shown to correlate with risk. In the study by Brodsky et al., a neck circumference of 40cm was associated with a 5% probability of problematic intubation whereas at 60cm, the probability was 35% (2002).

Although measuring a patient’s neck might not be appropriate, a reasonable estimate can be made on sight and used as guidance when determining anaesthetic induction and intubation. Due to difficulty in ventilating obese patients and increased risk of pulmonary aspiration, most obese patients will be intubated rather than relying on bag and mark ventilation or laryngeal mask airways.

Where there is a difficult airway, an awake fibre-optic intubation may be necessary rather than a conventional bag and mask induction. This can be stressful to an already anxious patient, so it’s important to consider the risk of a difficult intubation, and how this will be approached with the entire anaesthetic team.

Involving the patient as much as possible in all decisions is a good way of managing risk and preventing potential complications due to stress or anxiety.

Communication with the patient regarding intubation complications is essential before they arrive in the operating theatre suite.

Correct Equipment and Use

Correct equipment, and usage, is essential with the larger patient. A 2011 review of incidents reported to the National Patient Safety Agency (UK), highlighted that many of the cases referred were due to inadequate provision of suitable equipment for obese patients. Particular equipment necessary for the care of the larger patient (according to Nightingale et al, 2015) may include:

  • Bariatric operating table, able to incorporate arm boards and table extensions, attachments for positioning such as leg supports for the lithotomy position, and shoulder and foot supports
  • Gel pads and padding for pressure points
  • Wide Velcro strapping to secure the patient to the operating table
  • Ramping device/pillows
  • Raised step for the anaesthetist
  • Large tourniquets
  • Readily available difficult airway equipment
  • Anaesthetic ventilator capable of positive end-expiratory pressure and pressure modalities
  • Portable ultrasound machine
  • Hover-mattress or slide sheet
  • Long spinal and epidural needles
  • Long arterial lines if femoral access is necessary
  • Neuromuscular blockade monitor
  • Depth of anaesthesia monitoring to minimise residual sedation

Careful handling of an obese patient is crucial to prevent injuries to staff; making sure that available equipment is used correctly, and everyone involved with the patient has had the appropriate training. Mandatory training should include obese patient handling techniques. Sometimes it might be necessary to induce anaesthesia in the operating theatre, enabling the patient to move themselves on to the operating table rather than compromising staff safety.

Patient Positioning

Patient positioning in the operating theatre is about more than just ensuring good surgical access, and should be considered and discussed with the team long before the patient arrives in the operating theatre.

Supine positioning is tricky for obese patients, as it can make respiration difficult as well as compressing the inferior vena cava and impeding normal blood flow. Elevating the back where possible can alleviate this. The prone position carries the same problems – along with compression of the diaphragm – making ventilation extremely difficult.

Although lateral positioning is the least problematic for obese patients, it’s also the least favourable for many surgical procedures. So it’s important that you use common sense when positioning the patient and ensure that both the anaesthetist and lead surgeon have seen the positioning, supports, and additional devices used before the procedure commences. Accurate documentation of everything used should be undertaken.

Risk Factors

Every patient is at risk of developing complications from poor patient positioning and support… but the risk is greater with obese patients, and can include:

  • Pressure necrosis of skin and underlying tissue
  • Peripheral nerve injury
  • Back and joint pain
  • Reduced circulation
  • Compartment syndrome

Adequate padding is therefore essential, as the extra weight carried by the patient puts more pressure on the areas of skin that the operating table, and other equipment, comes into contact with.

An additional gel pad over the table can be of immense benefit, as can using an obese specific table where there’s one available – although most operating tables can safely accommodate up to 500lBs without losing functionality.

It’s worth noting that gel padding and supports are better for obese patients than their foam alternatives. This is because the foam can be easily compressed and lose its supportive structure. The Association of Perioperative Registered Nurses (2004) recommends that all padding and devices used for positioning maintains a normal capillary interface pressure of 32mmHg or less, to reduce the risk of operating theatre acquired pressure injury.

Whilst care of the larger patient is often undertaken with some trepidation, it can’t be denied that patient size is generally on the increase. Rather than an occasional need for additional awareness, equipment, and understanding, it’s becoming the norm to care for obese patients in all areas of anaesthesia, surgery, and post-anaesthetic care.

Appropriate training and understanding is essential if unwanted complications are to be avoided.

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