The management of patients with obesity during surgery requires additional planning and a thorough understanding of their altered physiology and anatomy, particularly when prone positioning is indicated for procedures. Historically, clinicians expressed concern that the prone position would exacerbate cardiorespiratory compromise in this population due to abdominal weight. However, contemporary evidence demonstrates that when correctly performed, prone positioning can actually improve pulmonary function, provided the abdomen is permitted to move freely.
In anesthetized and paralyzed patients with obesity, the supine position is associated with a marked reduction in functional residual capacity (FRC) and the development of atelectasis as the diaphragm is displaced cephalad by abdominal fat. Research by Pelosi et al. found that turning these patients from the supine to the prone position significantly increased FRC from an average of 0.894 liters to 1.980 liters. This increase in lung volume was accompanied by improved lung compliance and a significant rise in arterial oxygenation, likely due to the unloading of abdominal viscera and the recruitment of previously atelectatic alveolar regions.
Ensuring free abdominal movement is the critical technical requirement for achieving these physiological benefits. Specialized equipment, such as the Jackson operating table, which employs chest and pelvic bolsters to support the patient, can create more space for the abdomen compared to standard operating tables. In contrast, using equipment like parallel hard rubber rolls that do not guarantee abdominal freedom has been shown to decrease total respiratory compliance and increase peak airway pressures.
For patients with morbid obesity, defined as a BMI exceeding 40 kg/m2, the physical transfer of an anesthetized patient onto the operating table poses significant risks for both the surgical team and the patient, including potential pressure-related injuries or displacement of the endotracheal tube. A strategy for surgical patients with obesity that may mitigate these risks is the use of awake fiberoptic intubation followed by awake prone self-positioning by the patient before anesthesia induction. As described in a case study of a patient weighing 180 kg, this technique involves performing intubation under topical anesthesia and low-dose sedation before allowing the patient to physically move themselves onto the Jackson table. This approach allows the patient to confirm the comfort and safety of their own pressure points and eyes before general anesthesia is induced.
Intraoperatively, the surgical team must remain vigilant regarding prone-specific complications, including ischemic optic neuropathy (ION), which is associated with obesity, male sex, Wilson frame use, and high blood loss. Other risks include brachial plexus injuries from arm abduction greater than 90 degrees and compartment syndrome of the thighs. Protective lung ventilation strategies—incorporating low tidal volumes, recruitment maneuvers, and appropriate positive end-expiratory pressure (PEEP)—should be maintained. While a PEEP of 10 cmH2O is frequently utilized, some patients may require higher levels to maintain regional ventilation distribution.
References
- Pelosi, P., Croci, M., Calappi, E., et al. (1996). Prone Positioning Improves Pulmonary Function in Obese Patients During General Anesthesia. Anesthesia & Analgesia, 83(3), 578–583. https://journals.lww.com/anesthesia-analgesia/abstract/1996/09000/prone_positioning_improves_pulmonary_function_in.25.aspx
- Carron, M., Safaee Fakhr, B., Ieppariello, G., & Foletto, M. (2020). Perioperative care of the obese patient. British Journal of Surgery, 107(2), e39–e55. https://doi.org/10.1002/bjs.11447
- Epstein, N. E. (2017). More risks and complications for elective spine surgery in morbidly obese patients. Surgical Neurology International, 8, 66. http://surgicalneurologyint.com/More-risks-and-complications-for-elective-spine-surgery-in-morbidly-obese-patients/
- DePasse, J. M., Palumbo, M. A., Haque, M., Eberson, C. P., & Daniels, A. H. (2015). Complications associated with prone positioning in elective spinal surgery. World Journal of Orthopedics, 6(3), 351–359. http://doi.org/10.5312/wjo.v6.i3.351
- Douglass, J., Fraser, J., & Andrzejowski, J. (2014). Awake intubation and awake prone positioning of a morbidly obese patient for lumbar spine surgery. Anaesthesia, 69(2), 166–169. https://doi.org/10.1111/anae.12387