Pharmacologically Induced Ventilatory Depression in the Postoperative Patient: A Sleep-Wake State-Dependent Perspective

Incidence of postoperative opioid-induced respiratory depression episodes in patients on room air or supplemental oxygen: a post-hoc analysis of the PRODIGY trial

BACKGROUND

Supplemental oxygen (SO) potentiates opioid-induced respiratory depression (OIRD) in experiments on healthy volunteers. Our objective was to examine the relationship between SO and OIRD in patients on surgical units.

METHODS

This post-hoc analysis utilized a portion of the observational PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) trial dataset (202 patients, two trial sites), which involved blinded continuous pulse oximetry and capnography monitoring of postsurgical patients on surgical units. OIRD incidence was determined for patients receiving room air (RA), intermittent SO, or continuous SO. Generalized estimating equation (GEE) models, with a Poisson distribution, a log-link function and time of exposure as offset, were used to compare the incidence of OIRD when patients were receiving SO vs RA.

RESULTS

Within the analysis cohort, 74 patients were always on RA, 88 on intermittent and 40 on continuous SO. Compared with when on RA, when receiving SO patients had a higher risk for all OIRD episodes (incidence rate ratio [IRR] 2.7, 95% confidence interval [CI] 1.4-5.1), apnea episodes (IRR 2.8, 95% CI 1.5-5.2), and bradypnea episodes (IRR 3.0, 95% CI 1.2-7.9). Patients with high or intermediate PRODIGY scores had higher IRRs of OIRD episodes when receiving SO, compared with RA (IRR 4.5, 95% CI 2.2-9.6 and IRR 2.3, 95% CI 1.1-4.9, for high and intermediate scores, respectively).

CONCLUSIONS

Despite oxygen desaturation events not differing between SO and RA, SO may clinically promote OIRD. Clinicians should be aware that postoperative patients receiving SO therapy remain at increased risk for apnea and bradypnea.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT02811302, registered June 23, 2016.

Day-surgery adult patients with obesity and obstructive sleep apnea: Current controversies and concerns

Obesity and obstructive sleep apnea are considered independent risk factors that can adversely affect perioperative outcomes. A combination of these two conditions in the ambulatory surgery patient can pose significant challenges for the anesthesiologist. Nevertheless, these patients should not routinely be denied access to ambulatory surgery. Instead, patients should be appropriately optimized. Anesthesiologists and surgeons must work together to implement fast-track anesthetic and surgical techniques that will ensure successful ambulatory outcomes.

The effect of hyperoxia on ventilation during recovery from general anesthesia: A randomized pilot study for a parallel randomized controlled trial

STUDY OBJECTIVE

While supplemental O₂ inhalation corrects hypoxemia, its effect on post-anesthesia ventilation remains unknown. This pilot trial tested the hypothesis that hyperoxia increases the time spent with a transcutaneous PCO₂ (TcPCO₂) > 45 mmHg, compared with standard O₂ supplementation.

DESIGN

Single-blinded, parallel two-arm randomized pilot trial.

SETTING

University hospital.

PATIENTS

20 patients undergoing robotic-assisted laparoscopic nephrectomy.

MEASUREMENTS

After institutional approval and informed consent, patients were randomized to receive O₂ titrated to arterial saturation (SpO₂): 90-94% (Conservative O₂, N =10), or to SpO₂ > 96% (Liberal O₂, N = 10) for up to 90 min after anesthesia. Continuous TcPCO₂, respiratory inductance plethysmography (RIP), and SpO₂, were recorded. We calculated the percentage of time at TcPCO₂ > 45 mmHg for each patient and compared the two groups using analysis of covariance, adjusting for sex, age, and body mass index. We also estimated the sample size required to detect the between-group difference observed in this pilot trial. RIP signals were used to calculate apnea/hypopnea index (AHI), which was then compared between two groups.

MAIN RESULTS

The mean percentage of time with a TcPCO₂ > 45 mmHg was 80.6% for the Conservative O₂ (N=9) and 61.2% for the Liberal O₂ (N=10) group [between-group difference of 19.4% (95% CI: -18.7% to 57.6%), P = 0.140]. With an observed effect size of 0.73, we estimated that 30 participants per group are required, to demonstrate this difference with a power of 80% at a two-sided alpha of 5%. Means SpO₂ were 94.5% and 99.9% for the Conservative O₂ and the Liberal O₂ groups, respectively. AHI was significantly higher in the Conservative O₂, compared with the Liberal O₂ group (median AHI: 16 vs. 3; P = 0.0014).

CONCLUSIONS

Hyperoxia in the post-anesthesia period reduced the time spent at TcPCO₂ > 45 mmHg and significantly decreased AHI, while mean SpO₂ ranged inside the a priori defined limits.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04723433.

Perioperative considerations for adult patients with obstructive sleep apnea

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) is a common, but often undiagnosed, sleep breathing disorder affecting approximately a third of adult surgical patients. OSA patients have increased sensitivity to anesthetic agents, sedatives, and opioid analgesics.

RECENT FINDINGS

Newer technologies (e.g., bedside capnography) have demonstrated that OSA patients have repetitive apneic spells, beginning in the immediate postoperative period and peaking in frequency during the first postoperative night. Compared to patients without OSA, OSA patients have double the risk for postoperative pulmonary as well as other complications, and OSA has been linked to critical postoperative respiratory events leading to anoxic brain injury or death. Patients with OSA who have respiratory depression during anesthesia recovery have been found to be high-risk for subsequent pulmonary complications. Gabapentinoids have been linked to respiratory depression in these patients.

SUMMARY

Surgical patients should be screened for OSA and patients with OSA should continue using positive airway pressure devices postoperatively. Use of shorter acting and less sedating agents and opioid sparing anesthetic techniques should be encouraged. In particular, OSA patients exhibiting signs of respiratory depression in postanesthesia recovery unit should receive enhancer respiratory monitoring following discharge to wards.

INCIDENCE AND OUTCOMES OF LIFE-THREATENING EVENTS DURING HOSPITALIZATION: A RETROSPECTIVE STUDY OF PATIENTS TREATED WITH NALOXONE

BACKGROUND

We describe the clinical course of medical and surgical patients who received naloxone on general hospital wards for suspected opioid induced respiratory depression (OIRD).

METHODS

From May 2018 through October 2020, patients who received naloxone on hospital wards were identified and records reviewed for incidence and clinical course.

RESULTS

There were 86,030 medical and 106,807 surgical admissions. Naloxone was administered to 99 (incidence 11.5 [95%CI 9.4-14.0] per 10,000 admissions) medical and 63 (5.9 [95%CI 4.5-7.5]) surgical patients, P < 0.001. Median oral morphine equivalents administered within 24-hour before naloxone was 32 [15, 64] and 60 [32, 88] mg for medical and surgical patients, respectively, P = 0.002. Rapid response team was activated in 69 (69.7%) vs. 42 (66.7%) and critical care transfers in 51 (51.5%) vs. 30 (47.6%) medical and surgical patients respectively. In-hospital mortality was 21 (21.2%) vs. 2 (3.2%) and discharge to hospice 12 (12.1%) vs. 1 (1.6%), for medical and surgical patients respectively, P = 0.001. Naloxone did not reverse OIRD in 38 (23%) patients, and these patients had more transfers to the intensive care unit and 30-day mortality.

CONCLUSION

Medical inpatients are more likely to suffer OIRD than surgical inpatients despite lower opioid dose. Definitive OIRD was confirmed in 77% of patients because immediate naloxone response, while 23% of patients did not respond and this subset were more likely to need higher level of care and had higher 30-day mortality. Careful monitoring of mental and respiratory variables is necessary when opiates are used in hospital.