Prediction of postoperative respiratory depression and respiratory complications in patients on preoperative methadone.

PURPOSE: We developed prediction models for postoperative respiratory depression and respiratory complications for 958 patients who were on methadone preoperatively. METHODS: The primary outcome was postoperative respiratory depression as defined by respiratory rate < 10/min, oxygen saturation (SpO2) < 90%, or requirement of naloxone for 48 h postoperatively. Secondary outcome was the composite of postoperative respiratory complications. Prediction models for postoperative respiratory depression and respiratory complications were constructed using multivariate logistic regression with preoperative and intraoperative characteristics as the predictors. RESULTS: For the multivariate logistic regression model for postoperative respiratory depression, surgery duration (P = 0.005), body mass index (BMI) (P = 0.008), surgery involving digestive system (P = 0.031), and American Society of Anesthesiologists (ASA) physical status ≥ 4 (P = 0.038) were statistically significant predictors. The area under the receiver operating characteristic curve (AUROC) of the model was 0.581 (0.558-0.601) [median (95% confidence interval (CI))] with fivefold cross-validation. For the model for postoperative respiratory complications, surgery duration (P = 0.001), history of hypertension (P = 0.028), surgery involving musculoskeletal system (P < 0.001), surgery involving integumental system (P = 0.034), surgery categorized to miscellaneous therapeutic procedures (P = 0.028), combined general and regional anesthesia (P = 0.033), ASA physical status 3 (P < 0.001), and ASA physical status ≥ 4 (P < 0.001) were statistically significant predictors, and AUROC of the model was 0.726 (0.712-0.737). CONCLUSIONS: Multivariate logistic regression models including preoperative, and intraoperative characteristics as the predictors performed poorly to predict postoperative respiratory depression, and moderately for postoperative respiratory complications. Neither model is accurate enough to be subject to clinical use.

In-Hospital Opioid Consumption After the Previous Cesarean Delivery Weakly Predicts Opioid Consumption After Index Delivery: A Retrospective Cohort Study.

BACKGROUND: To predict opioid consumption and pain intensity after the index cesarean delivery, we tested a hypothesis that opioid consumption after the previous cesarean delivery of the same patient can predict the opioid consumption after the index cesarean delivery. We further tested a secondary hypothesis that the pain scores after the previous cesarean delivery can predict the pain scores after the index cesarean delivery. METHODS: This is a retrospective cohort study of 470 women who underwent both previous and index cesarean deliveries at a single institution from January 2011 to June 2019. To predict the opioid consumption (primary outcome) and average pain scores (on 11-point numeric rating scale) after their index cesarean delivery, we used a linear regression model incorporating only the opioid consumption and average pain scores after the previous cesarean delivery, respectively (unadjusted models). Demographic and obstetric variables were then added as predictors (adjusted models). The bootstrap was used to compare these models with respect to proportion of variance of the outcome accounted for (R2). RESULTS: Unadjusted models were weakly predictive of opioid consumption (R2 = 0.268; 95% confidence interval [CI], 0.146-0.368) and average pain scores (R2 = 0.176; 95% CI, 0.057-0.250). An adjusted model for opioid consumption was weakly predictive (R2 = 0.363; 95% CI, 0.208-0.478), but an adjusted model for average pain scores was not predictive of the outcomes (R2 = 0.070; 95% CI, -0.143 to 0.219). Adjusted models failed to explain variances of opioid consumption and average pain scores significantly better than unadjusted models (P = .099 and P = .141, respectively). CONCLUSIONS: Opioid consumption and pain scores after women's previous cesarean delivery only explain 27% of variance of opioid consumption and 18% of variance of their pain after their index cesarean delivery. Therefore, previous cesarean delivery analgesic metrics are not robust enough to be used as clinically applicable predictors for index delivery.

Obstetric Anesthesia During the COVID-19 Pandemic.

With increasing numbers of coronavirus disease 2019 (COVID-19) cases due to efficient human-to-human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United States, preparation for the unpredictable setting of labor and delivery is paramount. The priorities are 2-fold in the management of obstetric patients with COVID-19 infection or persons under investigation (PUI): (1) caring for the range of asymptomatic to critically ill pregnant and postpartum women; (2) protecting health care workers and beyond from exposure during the delivery hospitalization (health care providers, personnel, family members). The goal of this review is to provide evidence-based recommendations or, when evidence is limited, expert opinion for anesthesiologists caring for pregnant women during the COVID-19 pandemic with a focus on preparedness and best clinical obstetric anesthesia practice.

Association between perioperative non-steroidal anti-inflammatory drug use and cardiovascular complications after non-cardiac surgery in older adult patients.

BACKGROUND: We investigated in older adult non-cardiac surgical patients whether receipt of perioperative non-steroidal anti-inflammatory drugs (NSAIDs) is associated with increased incidence of postoperative cardiovascular complications. METHODS: We retrospectively extracted the information for patients with age ≥  65 years who had inpatient non-cardiac surgery with a duration of ≥  1 h from the American College of Surgeons-National Surgical Quality Improvement Program registry data acquired at the University of Washington Medical Center. We compared patients who received NSAIDs perioperatively to those who did not receive NSAIDs, on the two composite outcomes: (1) the incidence of postoperative cardiovascular complications within 30 days of the surgery, and (2) the incidence of combined postoperative gastrointestinal and renal complications, and length of postoperative hospital stay. We used separate multivariable logistic regression models to analyze the two composite outcomes and a Poisson regression model for the length of hospital stay. RESULTS: The receipt of perioperative NSAIDs was not associated with postoperative cardiovascular complications (estimated odds ratio (OR), 1.78; 95% confidence interval (CI), 0.97 to 3.25; P =  0.06), combined renal and gastrointestinal complications (estimated OR, 1.30; 95% CI, 0.53 to 3.20; P =  0.57), and length of postoperative hospital stay in days (incidence rate ratio, 1.06; 95% CI, 0.93 to 1.21; P =  0.39). CONCLUSIONS: In older adult non-cardiac surgical patients, receipt of perioperative NSAIDs was not associated with increased incidences of postoperative cardiovascular complications, and renal and gastrointestinal complications within 30 days after surgery, or length of postoperative hospital stay.

Association Between Postoperative Methocarbamol and Postoperative Pain Opioid Dose Requirements: A Retrospective Cohort Study.

OBJECTIVES: We tested the hypothesis that patients who received methocarbamol postoperatively experience less severe pain and require smaller doses of opioids than those who did not receive methocarbamol. MATERIALS AND METHODS: This is a retrospective cohort study of patients undergoing surgery involving the musculoskeletal system. Of 9089 patients, 704 received methocarbamol during 48 hours postoperatively, while 8385 did not receive methocarbamol. The patients who received methocarbamol postoperatively and the patients who did not receive methocarbamol were compared on the time-weighted average (TWA) pain score and opioid dose requirements in morphine milligram equivalents (MME) during the first 48 hours postoperatively, using propensity score-weighted regression models to adjusting for preoperative and intraoperative covariates. RESULTS: Postoperative 48-hour TWA pain scores were 5.5±1.7 (mean±SD), and 4.3±2.1 for methocarbamol and non-methocarbamol patients. Postoperative 48-hour opioid dose requirements in MME were 276 [170-347] (median [interquartile range (IQR)]) mg, and 190 [60-248] mg for methocarbamol and non-methocarbamol patients. In propensity score-weighted regression models, receiving methocarbamol postoperatively was associated with 0.97-point higher postoperative TWA pain score (95% CI, 0.83-1.11; P <0.001), and 93.6-MME higher postoperative opioid dose requirements (95% CI, 79.9 to 107.4; P <0.001), compared with not receiving methocarbamol postoperatively. DISCUSSION: Postoperative methocarbamol was associated with significantly higher acute postoperative pain burden and opioid dose requirements. Although the results of the study are influenced by residual confounding, they suggest a limited-if any-benefit of methocarbamol as an adjunct of postoperative pain management.

Postoperative respiratory depression in patients on sublingual buprenorphine: a retrospective cohort study for comparison between postoperative continuation and discontinuation of buprenorphine.

BACKGROUND: We tested the hypothesis that patients who continued buprenorphine postoperatively experience postoperative respiratory depression less frequently than those who discontinued buprenorphine. METHODS: This is a retrospective cohort study of patients who were on buprenorphine preoperatively. The primary outcome was postoperative respiratory depression as defined by respiratory rate < 10/minute, oxygen saturation (SpO2) < 90%, or requirement of naloxone for 48 h postoperatively. The secondary outcome was the composite of postoperative respiratory complications. The associations between postoperative buprenorphine continuation and respiratory depression and respiratory complications were estimated using separate multivariable logistic regression models, including demographic, intraoperative characteristics, and preoperative buprenorphine dose as covariates. RESULTS: Postoperative buprenorphine continuation was not associated with postoperative respiratory depression (adjusted odds ratio (OR), 1.11, 95% confidence interval (CI), 0.61 to 1.99, P=0.72). In subanalysis stratified by the preoperative buprenorphine dose, buprenorphine continuation was not associated with postoperative respiratory depression either when preoperative buprenorphine dose was high (≥16 mg daily) or low (<16 mg daily). Postoperative buprenorphine continuation was associated with lower incidence of postoperative respiratory complications (adjusted OR, 0.43, 95% CI, 0.21 to 0.86, P=0.02). CONCLUSIONS: Continuing buprenorphine was not associated with respiratory depression, but it was associated with a lower incidence of respiratory complications.

Comparison Between Preoperative Methadone and Buprenorphine Use on Postoperative Opioid Requirement: A Retrospective Cohort Study.

OBJECTIVES: Buprenorphine is a partial agonist at mu-opioid receptors and competes for these receptors with other opioids in vitro. Whether patients on buprenorphine maintenance require high doses of opioid analgesics to attain adequate postoperative pain control has not been determined. We evaluated differences in acute postoperative opioid consumption and pain burden between patients taking buprenorphine and those taking methadone preoperatively. MATERIALS AND METHODS: A retrospective review of medical records of 928 patients, of whom 195 were on buprenorphine and 733 were on methadone preoperatively, was performed. Among methadone and buprenorphine patients, 615 and 89, respectively, continued to receive the medications postoperatively. Buprenorphine patients were compared with methadone patients for the first 48 hours postoperatively with regard to acute opioid dose requirements (morphine milligram equivalents [MME] above their baseline buprenorphine and methadone doses) and time-weighted average (TWA) pain scores (using targeted maximum likelihood estimation). RESULTS: Opioid dose requirements for 48 hours postoperatively were 150 (22 to 297) (median [interquartile range]) and 220 [90 to 360] MME for buprenorphine and methadone patients, respectively. Preoperative buprenorphine was associated with a 59.9% lower postoperative MME (95% confidence interval: 46.6%-69.8%, P<0.0001) compared with methadone. Postoperative TWA pain scores for the first 48 hours were 5.0±2.7 (mean±SD), and 5.4±2.3 for buprenorphine and methadone patients, respectively. Preoperative buprenorphine was associated with a 0.37-point lower TWA pain score (95% confidence interval: 0.14-0.61, P=0.002) compared with methadone. DISCUSSION: Preoperative buprenorphine use was associated with >50% reduction in postoperative opioid dose requirement and a statistically significant, though clinically unimportant, reduction in acute pain burden in comparison to methadone. The study is limited by several important factors such as the exclusion of patients requiring intravenous patient-controlled analgesia, small number of patients were on higher dose of buprenorphine, and a large percentage of methadone patients were not on a stable dose of methadone yet.

Postoperative Pain and Opioid Dose Requirements in Patients on Sublingual Buprenorphine: A Retrospective Cohort Study for Comparison Between Postoperative Continuation and Discontinuation of Buprenorphine.

OBJECTIVE: To test the hypothesis that patients who continued buprenorphine postoperatively experience less severe pain and require a smaller dose of opioids than those who discontinued buprenorphine. MATERIALS AND METHODS: This is a retrospective cohort study of surgical patients who were on buprenorphine preoperatively. Using our previous study's data as pilot data, we selected the covariates to be included in 2 regression models with postoperative time-weighted average pain score and opioid dose requirements in morphine milligram equivalents during 48 hours after surgery as the outcomes. Both contained preoperative daily buprenorphine dose, whether buprenorphine was continued postoperatively, and the preoperative daily dose-by-postoperative continuation interaction as predictors. Precision variables were identified by exhaustive search of perioperative parameters with the exposure variables (preoperative daily dose, postoperative continuation, and their interaction) included in the regression model. The model selected by using the pilot data was estimated again using the new data extracted for this study to make inference about the effect of the 2 exposures (postoperative buprenorphine continuation and preoperative daily buprenorphine dose) and their interaction on the outcomes. RESULTS: Continuing buprenorphine was associated with a 1.3-point lower time-weighted average pain score than discontinuing (95% confidence interval, 0.39-2.21; P=0.005) but was not associated with a difference in opioid dose requirements (P=0.48). DISCUSSION: Continuing buprenorphine was associated with lower postoperative pain levels than discontinuing. Our results were primarily driven by patients on lower buprenorphine dose as only 22% of patients were on daily doses of 24 mg or above.

Acute Pain Burden and Opioid Dose Requirements after Cesarean Delivery in Parturients with Preexisting Chronic Back Pain and Migraine.

INTRODUCTION: Preexisting chronic pain has been reported to be a consistent risk factor for severe acute postoperative pain. However, each specific chronic pain condition has unique pathophysiology, and it is possible that the effect of each condition on postoperative pain is different. METHODS: This is a retrospective cohort study of pregnant women with preexisting chronic pain conditions (i.e., migraine, chronic back pain, and the combination of migraine + chronic back pain), who underwent cesarean delivery. The effects of the three chronic pain conditions on time-weighted average (TWA) pain score (primary outcome) and opioid dose requirements in morphine milligram equivalents (MME) during postoperative 48 hours were compared. RESULTS: The TWA pain score was similar in preexisting migraine and chronic back pain. Chronic back pain was associated with significantly greater opioid dose requirements than migraine (12.92 MME, 95% CI: 0.41 to 25.43, P=0.041). Preoperative opioid use (P < 0.001) was associated with a greater TWA pain score. Preoperative opioid use (P < 0.001), smoking (P=0.004), and lower postoperative ibuprofen dose (P=0.002) were associated with greater opioid dose requirements. CONCLUSIONS: Findings suggest women with chronic back pain and migraine do not report different postpartum pain intensities; however, women with preexisting chronic back pain required 13 MME greater opioid dose than those with migraine during 48 hours after cesarean delivery.

Lower, Variable Intrathecal Opioid Doses, and the Incidence of Prolonged Fetal Heart Rate Decelerations After Combined Spinal Epidural Analgesia for Labor: A Quality Improvement Analysis.

BACKGROUND: Combined spinal-epidurals with low-dose intrathecal opioids and local anesthetics are commonly used to initiate labor analgesia due to the fast onset of analgesia and good patient satisfaction. Intrathecal fentanyl has been associated with fetal bradycardia, and the rate may be higher at doses of 25 mcg and above. As such, our institution limits intrathecal fentanyl doses to less than 15 mcg for labor. Prompted by a few incidents of prolonged fetal bradycardia at even these low doses, we sought to audit the side effects associated with varying low doses of intrathecal fentanyl. METHODS: After IRB approval, a retrospective review was performed on 555 labor records from May-December, 2016. All the patients received combined spinal epidurals for labor analgesia. Intrathecal medication consisted of 1 mL of 0.25% bupivacaine, and varying fentanyl doses: 2.5, 5, 10, and 15 mcg. The incidences of prolonged fetal heart rate decelerations, emergent cesarean delivery, magnitude of pain reduction, pruritus requiring treatment, and hypotension were compared. RESULTS: Demographic variables were equivalent between the groups. There were no differences in the rates of prolonged fetal decelerations (in order of increasing fentanyl dose: 4.4%, 2.3%, 7.6%, 3.0%, p-value = 0.11), emergent cesarean delivery, magnitude of pain reduction, pruritus, or maternal hypotension. CONCLUSIONS: In conclusion, the rates of prolonged fetal heart rate decelerations after combined spinal epidural with intrathecal bupivacaine and fentanyl does not differ for fentanyl doses of 15 mcg and below.

Neuraxial anesthesia for postpartum tubal ligation at an academic medical center.

Background: Use of an in situ epidural catheter has been suggested to be efficient to provide anesthesia for postpartum tubal ligation (PPTL). Reported epidural reactivation success rates vary from 74% to 92%. Predictors for reactivation failure include poor patient satisfaction with labor analgesia, increased delivery-to-reactivation time and the need for top-ups during labor. Some have suggested that this high failure rate precludes leaving the catheter in situ after delivery for subsequent reactivation attempts. In this study, we sought to evaluate the success rate of neuraxial techniques for PPTL and to determine if predictors of failure can be identified. Methods: After obtaining IRB approval, a retrospective chart review of patients undergoing PPTL after vaginal delivery from July 2010 to July 2016 was conducted using CPT codes, yielding 93 records for analysis. Demographic, obstetric and anesthetic data (labor analgesia administration, length of epidural catheter in epidural space, top-up requirements, time of catheter reactivation, final anesthetic technique and corresponding doses for spinal and epidural anesthesia) were obtained. Results: A total of 70 patients received labor neuraxial analgesia. Reactivation was attempted in 33 with a success rate of 66.7%. Patient height, epidural volume of local anesthetic and administered fentanyl dose were lower in the group that failed reactivation. Overall, spinal anesthesia was performed in 60 patients, with a success rate of 80%. Conclusions: Our observed rate of successful postpartum epidural reactivation for tubal ligation was lower than the range reported in the literature. Our success rates for both spinal anesthesia and epidural reactivation for PPTL were lower than the generally accepted rates of successful epidural and spinal anesthesia for cesarean delivery. This gap may reflect a lower level of motivation on behalf of both the patients and anesthesia providers to tolerate "imperfect" neuraxial anesthesia once fetal considerations are removed.

Hormonal and Clinical Predictors for Post-egg Retrieval Pain in Women Undergoing Assisted Reproductive Technology Procedures.

OBJECTIVES: The intensity of post-egg retrieval pain is underestimated, with few studies examining postprocedural pain and predictors to identify women at risk for severe pain. We evaluated the influence of preprocedural hormonal levels, ovarian factors, and mechanical temporal summation (mTS) as predictors for post-egg retrieval pain in women undergoing in vitro fertilization. METHODS: Eighteen women scheduled for ultrasound-guided egg retrieval under standardized anesthesia and postprocedural analgesia were enrolled. Preprocedural mTS, questionnaires, clinical data related to anesthesia and the procedure itself, postprocedural pain scores, and pain medication for breakthrough pain were recorded. Statistical analysis included Pearson product-moment correlations, Mann-Whitney U tests, and multiple linear regressions. RESULTS: Average peak post-egg retrieval pain during the first 24 hours was 5.0±1.6 on a numerical response scale (0=no pain, 10=worst pain imaginable). Peak post-egg retrieval pain was correlated with basal antimullerian hormone (AMH) (r=0.549, P=0.018), preprocedural peak estradiol (r=0.582, P=0.011), total number of follicles (r=0.517, P=0.028), and number of retrieved eggs (r=0.510, P=0.031). Ovarian hyperstimulation syndrome (n=4) was associated with higher basal AMH (P=0.004), higher peak pain scores (P=0.049), but not with peak estradiol (P=0.13). The mTS did not correlate with peak postprocedural pain (r=0.266, P=0.286), or peak estradiol level (r=0.090, P=0.899). DISCUSSION: Peak post-egg retrieval pain intensity was higher than anticipated. Our results suggest that post-egg retrieval pain can be predicted by baseline AMH, high peak estradiol, and ovarian hyperstimulation syndrome. Further studies to evaluate intraprocedural and postprocedural pain in this population are needed, as well as clinical trials to assess postprocedural analgesia in women presenting with high hormonal levels.

Spinal anesthesia for cesarean delivery in a woman with neuromyelitis optica.

Neuromyelitis optica (NMO), or Devic's disease, is an idiopathic severe demyelinating disease that preferentially affects the optic nerve and spinal cord. Neuraxial anesthesia in women with multiple sclerosis is widely accepted, but reports of the use of neuraxial anesthesia in patients with NMO are scarce. We report the case of a morbidly obese primigravida undergoing a planned cesarean delivery at 32 weeks' gestation due to an acute exacerbation of NMO, managed with spinal anesthesia. Other than increased intraoperative hyperalgesia requiring inhaled nitrous oxide/oxygen, the mother experienced no apparent anesthetic-related complications.