New Articles by Dr. Nagappa

Is obstructive sleep apnea associated with difficult airway? Evidence from a systematic review and meta-analysis of prospective and retrospective cohort studies. 

Nagappa M, Wong DT, Cozowicz C, Ramachandran SK, Memtsoudis SG, Chung F. PLoS One. 2018 Oct 4;13(10):e0204904. doi: 10.1371/journal.pone.0204904. eCollection 2018. 


BACKGROUND: Difficult airway management and obstructive sleep apnea may contribute to increased risk of perioperative morbidity and mortality. The objective of this systematic review and meta-analysis (SRMA) is to evaluate the evidence of a difficult airway being associated with obstructive sleep apnea (OSA) patients undergoing surgery.

METHODS: The standard databases were searched from 1946 to April 2017 to identify the eligible articles. The studies which included adult surgical patients with either suspected or diagnosed obstructive sleep apnea must report at least one difficult airway event [either difficult intubation (DI), difficult mask ventilation (DMV), failed supraglottic airway insertion or difficult surgical airway] in sleep apnea and non-sleep apnea patients were included.

RESULTS: Overall, DI was 3.46-fold higher in the sleep apnea vs non-sleep apnea patients (OSA vs. non-OSA: 13.5% vs 2.5%; OR 3.46; 95% CI: 2.32-5.16, p <0.00001). DMV was 3.39-fold higher in the sleep apnea vs non-sleep apnea patients (OSA vs. non-OSA: 4.4% vs 1.1%; OR 3.39; 95% CI: 2.74-4.18, p <0.00001). Combined DI and DMV was 4.12-fold higher in the OSA vs. non-OSA patients (OSA vs. non-OSA: 1.1% vs 0.3%; OR 4.12; 95% CI: 2.93-5.79, p <0.00001). There was no significant difference in the supraglottic airway failure rates in the sleep apnea vs non-sleep apnea patients (OR: 1.34; 95% CI: 0.70-2.59; p = 0.38). Meta-regression to adjust for various subgroups and baseline confounding factors did not impact the final inference of our results.

CONCLUSION: This SRMA found that patients with obstructive sleep apnea had a three to four-fold higher risk of difficult intubation or mask ventilation or both, when compared to non-sleep apnea patients.

Read the full article on PLOS ONE

Opioids, respiratory depression, and sleep-disordered breathing.  

Nagappa M, Weingarten TN, Montandon G, Sprung J, Chung F. Best Pract Res Clin Anaesthesiol. 2017 Dec;31(4):469-485. doi: 10.1016/j.bpa.2017.05.004. Epub 2017 May 22.


The increasing use of opioids in the perioperative period has increased opioid-associated morbidity and mortality. There is a well-established connection between opioids, sleep-disordered breathing (SDB), and respiratory depression. The treatment of postoperative pain with opioids in patients with SDB may result in respiratory depression. In an unmonitored setting, it may lead to life-threatening respiratory events. More studies are required to evaluate the effective management and prevention of respiratory depression in patients with SDB. This review summarizes the current state of knowledge relating to the pathophysiology of respiratory depression by opioids and opioid-related respiratory depression and appraises the association between opioids and SDB.

Read more on PubMed