Lung Protection During Bariatric Surgery - Lung Protection During Bariatric Surgery – adapted anaesthesia methods — Lung Protection During Bariatric Surgery
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Summary

Obesity has become a major global health challenge and is expected to become even more widespread.¹The overall number of overweight and obese people worldwide increased from 857 million in 1980 to 2.1 billion in 2013.² Patients who are obese present a certain set of challenges and require specific perioperative care, as they have a higher risk of complications. In addition, placing obese patients in a supine position further reduces respiratory compliance. Therefore, different methods in ventilation and positioning must be used to improve pre-oxygenation, induction and recovery. Based on current literature, we discuss here how to minimise the higher risk of complications in obese patients.

Lung protective ventilation of obese patients during general anaesthesia

As the prevalence of obesity increases worldwide, obese surgical patients present a growing challenge for physicians in the operating room. Obesity, especially morbid obesity (body mass index of over 40.0 kg.m2), results in reduced lung volumes, significant atelectasis in dependent lung regions and a ventilation/perfusion mismatch. At the same time, oxygen consumption and the work of breathing increase.³ This amplifies the risks associated with general anaesthesia and makes obese patients prone to severe perioperative complications.³ An altered strategy to pre-oxygenation and induction for obese patients may be considered, as desaturation occurs quickly in the lungs and airway management can be more difficult.

Obesity during the induction phase: what we should keep in mind

Standard anaesthesia induction includes a brief period of pre-oxygenation followed by anaesthetic drugs, a test of manual ventilation and endotracheal intubation or placement of a supraglottic airway. This standard approach suffices for most patients. But obesity can complicate the perioperative oxygenation and ventilation of surgical patients and is a frequently mentioned risk factor for mask ventilation and/or tracheal intubation⁴. In addition to the technical challenges, the reduced lung volumes (i.e. FRC), increased ventilation-perfusion mismatch and respiratory comorbidities make anaesthetic induction and airway management high-risk for hypoxemic events and other respiratory complications⁵. Therefore, obese patients may require approaches tailored to their physiology before, during and after surgery.

Effective pre-oxygenation and induction for obese patients whitepaper

Effective Pre-oxygenation and Induction in Obese Patients

Read about the challenges that anaesthetists face when dealing with obese patients – and learn more about the strategies available to safely and best manage these cases, including recommendations for pre-oxygenation and induction.

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Technology insights: induction in obese patients

Read about how the right technology can support you when managing obese patients during general anaesthesia.

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Infographic: Obesity in general anaesthesia

Obesity in general anaesthesia infographic

There is an increased recognition that obese patients require specific care during surgery. Take a look at our summary of pre- and postoperative management of obese patients.

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Intraoperative ventilation of obese patients: minimising postoperative pulmonary risks

The anatomical and physiological peculiarities of obesity affect the entire process of general anaesthesia. This is especially true when the patient is in supine or Trendelenburg position. The FRC and EELV may be significantly reduced due to an increased amount of atelectasis. This can result in severe postoperative pulmonary complications.

To prevent such complications, lung-protective intraoperative ventilation is essential. To avoid atelectasis and ensure sufficient ventilation when applying the recommended parameters (especially low pressures), a recruitment manoeuvre (RM) allows lung compliance to increase or even normalise. When properly performed, an RM can increase FRC by opening the atelectatic lung areas, thus preventing hypoxemia while improving oxygen saturation and airway compliance.

Intraoperative ventilation of obese patients

This whitepaper focuses on ventilation during the maintenance phase of anaesthesia. Get an overview of important clinical aspects for minimising risks for obese patients during intraoperative ventilation – and read more on expert opinions and practical hints on various aspects of protectively ventilating obese patients in the operating room.

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Obese patients during recovery and in the postoperative phase

Obese patients not only require adapted approaches during pre-oxygenation, induction and maintenance of general anaesthesia, but modified respiratory care techniques in the immediate postoperative period have also been shown to be important in preventing postoperative pulmonary complications.

Anaesthetists ventilate obese patient in elevated position

Risks

Obese patients suffering from obstructive sleep apnoea (OSA) or from obesity hypoventilation syndrome (OHS) may be at high risk of postoperative pulmonary complications (PPCs), as opiate sensitivity adds to the severity of nocturnal hypoxia.⁶

They are also more likely to develop post-operative acute respiratory failure and have higher rates of pneumonia. Morbidly obese patients are known to have significantly more and longer-lasting atelectasis preoperatively when compared to non-obese patients.⁷ This further increases the work of breathing, as the patient breathes at lower lung volumes. In turn, this is associated with early airway closure and expiratory flow limitations, resulting in the development of intrinsic PEEP (PEEPi). These factors are worsened in the supine position – a potential challenge in the recovery room.⁶

Anaesthetist checks patient stats during surgery

Recommendations

In light of these factors, obese patients should be kept in an elevated position, such as the reverse Trendelenburg position or with elevated head and torso. This helps to mitigate intra-abdominal pressure effects on the lungs and improves oxygenation and lung compliance. Continuous positive airway pressure (CPAP) and non-invasive ventilation (NIV) can also be beneficial since they help to restore and maintain lung volumes particularly in morbidly obese patients. CPAP applied immediately after extubation as compared to deferring initiation of external CPAP to the recovery room, can help improve spirometry. NIV has also been demonstrated to be safe and feasible. One study demonstrated a 16% reduction in risk for post-extubation respiratory failure by the application of NIV immediately after extubation of patients with a BMI of >35. In addition to this, postoperative early mobilisation and respiratory physiotherapy is recommended.⁶

Technology insight: recovery of obese patients

Gain more insight into how our latest ventilation technologies in our anaesthesia workstations can enable successful protective ventilation strategies and support the transition to spontaneous breathing in obese patients during recovery.

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Get in touch with Dräger

Draeger Australia Pty. Ltd.

8 Acacia Place
Notting Hill
Victoria 3168

1800 372 437

Draeger New Zealand Ltd.

Unit 4
24 Bishop Dunn Place
East Tamaki
Auckland 2013

0800 372 437

Sources

¹ Candiotti K, Sharma S, Shankar R. Obesity, obstructive sleep apnoea, and diabetes mellitus: anaesthetic implications. Br J Anaesth 2009;103 (Suppl. 1):i23–30.

² Ng M, Fleming T, Robinson M, et al: Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 2014;384:766-781.

³ Pelosi P, Croci M, Ravagnan I, et al. The effects of body mass on lung volumes, respiratory mechanics, and gas exchange during general anesthesia. Anesth Analg 1998;87:654–60.

⁴ Pelosi P, Gregoretti C. Perioperative management of obese patients. Best Pract Res Clin Anaesthesiol. 2010;24(2):211–225.

⁵ Santesson J. Oxygen transport and venous admixture in the extremely obese. Influence of anaesthesia and artificial ventilation with and without positive end-expiratory pressure. Acta Anaesthesiologica Scandinavica 1976; 20: 387–94.

Lung Protection During Bariatric Surgery