To the Editor:

The characterization by Dahan et al.  1of overt opioid-induced respiratory depression (OIRD) requiring intervention in postoperative patients as rare and uncommon is troubling.

“Failure to Rescue” and postoperative respiratory failure (also known as Code Blue) are the first and third most common patient safety-related adverse events affecting the Medicare population in U.S. hospitals, accounting for 113 events per 1,000 at-risk patient admissions, and they result in death or anoxic brain injury in the majority of cases.*The resuscitation literature suggests that the most common antecedent vital sign abnormality to a cardiopulmonary arrest is respiratory in nature, and the worst outcomes often occur on the general care floor (GCF) and in patients whose preexisting morbidity score is low.2–4Fifty percent of Code Blue events involve patients receiving opioid analgesia.5 

Diagnosing narcotic overdoses in hospitalized patients is difficult and often missed; yet, this circumstantial evidence implicating opioids in serious adverse events in the resuscitation literature is not apparent in the anesthesia literature. This may be because the anesthesia literature myopically focuses on surrogate measures of respiratory depression such as respiratory rate and Spo2. These measures not only provide very “limited information” and are “loose indicators” of ventilatory adequacy, as acknowledged by Dahan et al. , but our literature also suffers from a lack of standardization, uses arbitrary threshold criteria, and predominantly comprises retrospective analysis of intermittent and manually charted data.6As such, these data are unreliable when compared with automated and continuous vital sign measurements, are prone to undersampling, and are likely underpowered to “connect the dots” with regard to the outcomes in the resuscitation literature.

Our failure on the GCF is not one of “rescue” but of “recognition.” OIRD is a preventable adverse event, and 78% of cardiac arrests on the GCF are deemed avoidable in root cause analysis.3The odds of a potentially avoidable cardiac arrest were five times higher on the GCF than in an intensive care setting, and outcomes are worst during periods of decreased vigilance, such as nights and weekends.7,8Recent vital signs, such as a respiratory rate, are missing in as many as 75% of patients for whom a Code Blue or a rapid response team is summoned.9 

The Anesthesia Patient Safety Foundation convened a symposium in 2006 on the dangers of postoperative opioids, and the consensus opinion was that OIRD remains a significant and preventable threat to patient safety for which institutions must have zero tolerance.†In recognition of the gravity of the problem, the 2011 edition of a preeminent nursing text on monitoring patients on opioids recommends that the monitoring interval for vital signs GCF could be greatly reduced, despite the additional burden imposed on the GCF nursing staff.10 

Three demographic trends are likely to make OIRD more prevalent in the future. The population is aging and obesity is more common, both of which predispose patients to obstructive sleep apnea. Recurrent airway obstruction due to opioid-mediated suppression of the arousal response and the upper airway dilators is the predominant feature of respiratory compromise in postoperative patients with obstructive sleep apnea.11Chronic opioid use for both medical and nonmedical reasons is escalating, and these patients are predisposed to have ataxic breathing patterns and frequent central apneas.12This predisposition in combination with the higher opioid doses and multimodal opioid therapy they require for adequate pain relief places them at an increased risk of respiratory compromise. Yet, the irregular breathing patterns and transient desaturations that precede respiratory decompensation in these patients are unlikely to be detected by intermittent respiratory rate and Spo2measurements.

Improved understanding by clinicians of the complex pharmacologic nuances of opioids and expanded use of multimodal, opioid-sparing analgesic techniques are important contributors to reducing OIRD. But recognition of the scope of OIRD and improving its detection remain pressing unresolved issues in postoperative pain management.

Medical University of South Carolina, Charleston, South Carolina.


Dahan A, Aarts L, Smith T: Incidence, reversal, and prevention of opioid-induced respiratory depression. Anesthesiology 2010; 112:226–38
Schein RM, Hazday N, Pena M, Ruben BH, Sprung CL: Clinical antecedents to in-hospital cardiopulmonary arrest. Chest 1990; 98:1388–92
Hodgetts T, Kenward G, Vlackonikolis I, Payne S, Castle N, Crouch R, Ineson N, Shaikh L: Incidence, location, and reasons for avoidable in-hospital cardiac arrest in a district general hospital. Resuscitation 2002; 54:115–23
Bowker L, Stewart K: Predicting unsuccessful cardiopulmonary resuscitation (CPR): A comparison of three morbidity scores. Resuscitation 1999; 40:89–95
Fecho K, Jackson F, Smith F, Overdyk F: In-hospital resuscitation: Opioids and other factors influencing survival. Ther Clin Risk Manag 2009; 5:961–8
Ko S, Goldstein DH, VanDenKerkhof EG: Definitions of “respiratory depression” with intrathecal morphine postoperative analgesia: A review of the literature. Can J Anaesth 2003; 50:679–88
Peberdy MA, Ornato JP, Larkin GL, Braithwaite RS, Kashner TM, Carey SM, Meaney PA, Cen L, Nadkarni VM, Praestgaard AH, Berg RA; National Registry of Cardiopulmonary Resuscitation Investigators: Survival from in-hospital cardiac arrest during nights and weekends. JAMA 2008; 299:785–92
National Registry of Cardiopulmonary Resuscitation Investigators
Sandroni C, Nolan J, Cavallaro F, Antonelli M: In-hospital cardiac arrest: Incidence, prognosis and possible measures to improve survival. Intensive Care Med 2007; 33:237–45
Chen J, Hillman K, Bellomo R, Flabouris A, Finfer S, Cretikos M: The impact of introducing medical emergency team system on the documentations of vital signs. Resuscitation 2009; 80:35–43
Pasero C, Quinn TE, Portenoy RK, McCaffery M, Rizos A: Management of opioid-induced adverse effects, Pain Assessment and Pharmacologic Management. Edited by Pasero C, McCaffery M. In press
White DP: Opioid-induced suppression of genioglossal muscle activity: Is it clinically important? J Physiol 2009; 587:3421–2
Walker JM, Farney RJ, Rhondeau S, Boyle KM, Valentine K, Cloward T, Shilling KC: Chronic opioid use is a risk factor for the development of central sleep apnea and ataxic breathing. J Clin Sleep Med 2007; 3:445–62