BARIATRIC SURGERY
highlights obese patients as being at increased risk of accidental awareness.5 For obese patients, depth of anaesthesia monitoring is recommended.6 However, the authors of NAP5 point out that such monitors are very rarely used in the UK. It is estimated that just 2.8% of all general anaesthetics involve the use of any form of depth of anaesthesia monitoring, despite guidance from NICE.5 Due to the increasing prevalence of obesity in the UK, anaesthetists are increasingly seeing overweight and obese patients in routine practice. But do they know what constitutes ‘best practice’ for this patient population, and is the right equipment being made available in UK theatres? There is evidence to suggest that there is poor awareness of important guidelines, so the question arises: are these patients getting the safest possible care?
Peri-operative challenges In 2011, a major report from the Royal College of Anaesthetists and The Difficult Airway Society (the 4th National Audit Project [NAP4]) showed that obese patients have double the risk of airway problems during an anaesthetic and made key recommendations to improve outcomes.7 The project, which identified that 2.9 million general anaesthetics are given in the UK each year, monitored all major complications of airway management that occurred in these patients and in ICUs and in emergency departments throughout the UK in 2008-2009. It studied only events serious enough to lead to death, brain damage, ICU admission or urgent
insertion of a breathing tube in the front of the neck. The report had several findings and recommendations; but those on obesity and the monitoring of breathing were among the most striking.
In addition to the two-fold increased risk of obese patients developing serious airway problems during an anaesthetic, the study also found that patients with severe obesity were four times more likely to develop such problems. In addition, obese patients were more likely to die if they sustained airway complications in ICU. Some obese patients died from complications of general anaesthesia while undergoing procedures that could have been performed under local or regional anaesthesia (where only part of the patient’s body is anaesthetised). In some cases, this alternative appeared not to be considered. Airway problems were more likely
to result in death in patients sedated on ICUs than if they occurred during anaesthesia for surgery. Half of the reports of events on ICUs described a patient death from the complication, whereas 12% died when the complication occurred during anaesthesia. Of the events reported from ICU 61% led to death or brain damage, compared to 14% of events during anaesthesia.
The most important finding was that the absence of a breathing monitor (capnograph) contributed to 74% of airway-related deaths reported from ICUs. The authors said that if the monitor had been used it would have identified problems at an earlier stage and so could have prevented some of the deaths altogether.
The capnograph, which detects
exhaled carbon dioxide, is used almost universally in anaesthesia but only sporadically in ICUs. Several authors and organisations have recommended that it should be used routinely in ICUs but, at the time of the report, this did not appear to be happening. Although the poor physical condition of patients needing to be in ICU possibly accounted for some the difference in outcome, the report identified several other causes: n Patients on ICU who are at risk of airway problems were less likely to be identified (and their management changed) than when undergoing anaesthesia
n The range of equipment available to manage patients with difficult airways is often less extensive in ICU compared to patients being anaesthetised in operating theatres
n Changes in training mean that the junior doctors looking after patients out of hours on ICU may have little experience in the management of difficult airway problems
n Rescue techniques (procedures performed to resolve a problem with the airway) are less likely to be successful in ICU compared to during anaesthesia.
A total of 11 recommendations were made by the report, including: n Hospital management need to be aware of the additional time and resources needed to safely anaesthetise obese patients
n Provision must be made for anaesthetists to evaluate obese patients before surgery. Morbidly obese patients and obese patients with significant co-morbidity should be formally assessed by an anaesthetist in a setting without time limitations
n Obese patients require thorough preoperative evaluation of co- morbidities. Evidence of obstructive sleep apnoea should be sought routinely
n Airway assessment should form part of the evaluation of all obese patients and should include an evaluation of possible rescue techniques
n Awake intubation should be considered in those patients in whom it would be difficult to establish rescue oxygenation or
26 l JULY 2018 l OPERATING THEATRE
©satyrenko - Fotolia
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