Evaluating residual anti-Xa levels following discontinuation of treatment-dose enoxaparin in patients presenting for elective surgery: a prospective observational trial.

INTRODUCTION: Prior studies have demonstrated that patients presenting for elective surgery may have higher-than-expected residual anti-Xa level activity at or beyond 24 hours following their last treatment dose of enoxaparin. Given that 24 hours of abstinence is currently recommended by both European and American societies before the performance of neuraxial or deep anesthetic/analgesic procedures, determining the actual timeframe at which residual anti-Xa level activity reliably falls below 0.2 IU/mL, the lower limit of the target range for thromboprophylaxis, is critical. METHODS: This was a prospective observational trial. Consenting patients on treatment-dose enoxaparin were randomized to either a 24-hour group (last dose at 07:00 the day prior to surgery) or a 36-hour group (last dose at 19:00 2 days prior to surgery). On arrival for surgery, blood samples were obtained to assess residual anti-Xa level activity and renal function. The primary outcome was residual anti-Xa level activity following the last treatment dose of enoxaparin. Incorporating all patients, linear regression modeling was performed to predict the timepoint at which the level of anti-Xa activity reliably fell below 0.2 IU/mL. RESULTS: 103 patients were analyzed. Time from the last dose at which residual anti-Xa activity fell below 0.2 IU/mL, based on the upper bound of the 95% CI, was 31.5 hours. No correlation overall between age, renal function, or sex was found. CONCLUSION: Residual levels of anti-Xa activity do not reliably fall below 0.2 IU/mL 24 hours following discontinuation of treatment-dose enoxaparin. Therefore, current time-based guidelines are not conservative enough. Routine anti-Xa testing should be strongly considered, or current time-based guidelines should be reassessed. TRIAL REGISTRATION NUMBER: NCT03296033.

Ilioinguinal/Iliohypogastric versus quadratus lumborum nerve blockade for elective open inguinal herniorrhaphy: a prospective, randomized, double-blinded, equivalency trial.

BACKGROUND: Open inguinal herniorrhaphy (OIH) is a commonly performed surgical procedure with expected postoperative pain. Historically, an option for regional analgesia has been an ilioinguinal and iliohypogastric nerve block (IINB). More recently, the transmuscular quadratus lumborum block (QLB) has been used as an analgesic technique for a variety of abdominal and truncal surgical procedures. Given our own institutional experiences with the performance of QLB combined with the body of literature supporting the proximal blockade of the ilioinguinal and iliohypogastric nerves via this approach, we compared the analgesia provided by an IINB to a QLB. We hypothesized that the two blocks would provide equivalent analgesia, as defined by a difference of less than±2 points on the pain scale (0-10 numeric rating scale (NRS)), for patients undergoing OIH. METHODS: Sixty patients scheduled for elective outpatient OIH under general anesthesia were randomized to preoperatively receive either an IINB or a transmuscular QLB with 0.25% bupivacaine/epinephrine/clonidine for postoperative analgesia. The primary endpoint was movement NRS pain scores at 8 hours. Secondary outcomes included resting NRS pain scores at 8 and 24 hours, movement NRS pain scores at 24 hours, incidence of opioid related side effects (nausea, vomiting, pruritus), time-to-first oral opioid analgesic, and total opioid consumption at 24 hours. RESULTS: Fifty-nine patients were analyzed per an intention-to-treat approach (one patient was excluded because the surgical procedure was canceled). Movement pain scores at 8 hours were equivalent (IINB 5.10±3.02 vs QLB 5.03±3.01 (mean NRS±SD); two one-sided test mean difference (90% CI), 0.07 (-1.24 to 1.38), p ≤0.01). There were no differences between groups for any of the secondary endpoints. CONCLUSION: An IINB and a transmuscular QLB are equivalent with regards to their ability to provide postoperative analgesia after OIH.

Analgesic Benefit of Pectoral Nerve Block II Blockade for Open Subpectoral Biceps Tenodesis: A Randomized, Prospective, Double-Blinded, Controlled Trial.

BACKGROUND: Axillary pain is common after arthroscopic shoulder surgery with an open subpectoral biceps tenodesis. We hypothesized that adding a pectoral nerve block II (Pecs II) to an interscalene block (ISB) would improve postoperative analgesia in this surgical population. METHODS: Forty patients were enrolled in this prospective, randomized, observer and patient-blinded, single-institution trial. All 40 patients received a single-injection ISB with 20 mL of 0.25% bupivacaine with 1:400,000 epinephrine and 1:600,000 clonidine. The intervention arm (ISB + Pecs II) consisted of 20 patients who also received a Pecs II block using 30 mL of 0.25% bupivacaine with 1:400,000 epinephrine and 1:600,000 clonidine. The 20 control group patients (ISB) received a sham Pecs II block. The primary outcome was postoperative pain scores at 6 hours using the numeric rating scale (NRS; range, 0-10) and was analyzed using the Mann-Whitney U test. Secondary outcomes included the presence of axillary pain at 6 hours, the need for postanesthesia care unit (PACU) opioids, PACU length of stay (LOS) (minutes), NRS pain scores at 24 hours, cumulative opioid usage postdischarge through 24 hours, the presence of nausea or vomiting during the first 24 hours, and Pecs II block duration (in hours, based on time to onset of axillary pain). Data were analyzed using a modified intention-to-treat (ITT) methodology. RESULTS: Pain scores (NRS, 0-10) at 6 hours differed significantly between groups: ISB 3.0 (0.25-5.0) (1.7-4.3) versus ISB + Pecs II 0.0 (0-2.0) (0.0-1.1) (median [IQR] [95% CI]); P = .026. Hodges-Lehmann estimator of the difference was 2.0 (95% CI, 0.0-4.0). Fewer patients in the ISB + Pecs II group reported axillary pain at 6 hours and fewer required opioids in the PACU. There were no differences in any of the remaining secondary outcomes. CONCLUSIONS: The addition of a Pecs II block to an ISB for patients undergoing arthroscopic shoulder surgery with an open subpectoral biceps tenodesis significantly improved postoperative analgesia and reduced the need for opioids in the PACU.

Perineural dexamethasone successfully prolongs adductor canal block when assessed by objective pinprick sensory testing: A prospective, randomized, dose-dependent, placebo-controlled equivalency trial.

STUDY OBJECTIVE: To determine whether perineural dexamethasone prolongs peripheral nerve blockade (PNB) when measured objectively; and to determine if a 1 mg and 4 mg dose provide equivalent PNB prolongation compared to PNB without dexamethasone. SETTING: Multiple studies have reported that perineural dexamethasone added to local anesthetics (LA) can prolong PNB. However, these studies have relied on subjective end-points to quantify PNB duration. The optimal dose remains unknown. We hypothesized that 1 mg of perineural dexamethasone would be equivalent in prolonging an adductor canal block (ACB) when compared to 4 mg of dexamethasone, and that both doses would be superior to an ACB performed without dexamethasone. DESIGN: This was a prospective, randomized, double-blind, placebo-controlled equivalency trial involving 85 patients undergoing a unicompartmental knee arthroplasty. INTERVENTIONS: All patients received an ACB with 20 ml of 0.25% bupivacaine with 1:400,000 epinephrine. Twelve patients had 0 mg of dexamethasone (placebo) added to the LA mixture; 36 patients had 1 mg of dexamethasone in the LA; and 37 patients had 4 mg of dexamethasone in the LA. MEASUREMENTS: The primary outcome was block duration determined by serial neurologic pinprick examinations. Secondary outcomes included time to first analgesic, serial pain scores, and cumulative opioid consumption. MAIN RESULTS: The 1 mg (31.8 ±â€¯10.5 h) and 4 mg (37.9 ±â€¯10 h) groups were not equivalent, TOST [Mean difference (95% CI); 6.1 (-10.5, -2.3)]. Also, the 4 mg group was superior to the 1 mg group (p-value = 0.035), and the placebo group (29.7 ±â€¯6.8 h, p-value = 0.011). There were no differences in opioid consumption or time to analgesic request; however, some pain scores were significantly lower in the dexamethasone groups when compared to placebo. CONCLUSION: Dexamethasone 4 mg, but not 1 mg, prolonged the duration of an ACB when measured by serial neurologic pinprick exams. CLINICAL TRIAL REGISTRATION: NCT02462148.