Continuous Transversus Abdominis Plane Block for Primary Open Inguinal Hernia Repair: A Randomized, Double-Blind, Placebo-Controlled Trial.

OBJECTIVE: Patients undergoing open inguinal hernia repair may experience moderate to severe postoperative pain. We assessed opioid consumption in subjects who received a continuous transversus abdominis plane block in addition to standard multimodal analgesia. DESIGN: Randomized, double-blind, placebo-controlled. SETTING: Tertiary academic medical center. SUBJECTS: Adult patients undergoing open inguinal hernia repair at Virginia Mason Medical Center. A total of 90 patients were enrolled. METHODS: Subjects presenting for surgery were randomized to receive either a continuous transversus abdominis plane block or a subcutaneous sham block. The primary outcome was opioid consumption within the first 48 hours after surgery. Secondary outcomes included pain scores, activities assessment scores, and opioid-related adverse events. Multimodal analgesia utilized in both groups included acetaminophen, nonsteroidal anti-inflammatory drugs, and surgical local anesthetic infiltration. RESULTS: Eighty-two subjects, 42 from the block group and 40 from the sham group, completed the study, per protocol. The intention-to-treat analysis demonstrated no difference in 48-hour postoperative oxycodone equivalent consumption between the block and sham groups (27.8 mg ± 26.8 vs 32 mg ± 39.2, difference -4.4 mg, P = 0.55). There was a statistically significant reduction in pain scores at 24 hours in the block group. There were no other differences in secondary outcomes. CONCLUSIONS: Continuous transversus abdominis plane blocks provide modest improvements in pain after open inguinal hernia repair but fail to significantly reduce opioid consumption or improve functional activity levels in the setting of multimodal analgesia use.

Comparison of Anterior Suprascapular, Supraclavicular, and Interscalene Nerve Block Approaches for Major Outpatient Arthroscopic Shoulder Surgery: A Randomized, Double-blind, Noninferiority Trial.

BACKGROUND: The interscalene nerve block provides analgesia for shoulder surgery, but is associated with diaphragm paralysis. One solution may be performing brachial plexus blocks more distally. This noninferiority study evaluated analgesia for blocks at the supraclavicular and anterior suprascapular levels, comparing them individually to the interscalene approach. METHODS: One hundred-eighty-nine subjects undergoing arthroscopic shoulder surgery were recruited to this double-blind trial and randomized to interscalene, supraclavicular, or anterior suprascapular block using 15 ml, 0.5% ropivacaine. The primary outcome was numeric rating scale pain scores analyzed using noninferiority testing. The predefined noninferiority margin was one point on the 11-point pain scale. Secondary outcomes included opioid consumption and pulmonary assessments. RESULTS: All subjects completed the study through the primary outcome analysis. Mean pain after surgery was: interscalene = 1.9 (95% CI, 1.3 to 2.5), supraclavicular = 2.3 (1.7 to 2.9), suprascapular = 2.0 (1.4 to 2.6). The primary outcome, mean pain score difference of supraclavicular-interscalene was 0.4 (-0.4 to 1.2; P = 0.088 for noninferiority) and of suprascapular-interscalene was 0.1 (-0.7 to 0.9; P = 0.012 for noninferiority). Secondary outcomes showed similar opioid consumption with better preservation of vital capacity in the anterior suprascapular group (90% baseline [P < 0.001]) and the supraclavicular group (76% [P = 0.002]) when compared to the interscalene group (67%). CONCLUSIONS: The anterior suprascapular block, but not the supraclavicular, provides noninferior analgesia compared to the interscalene approach for major arthroscopic shoulder surgery. Pulmonary function is best preserved with the anterior suprascapular nerve block.

Comparison of Continuous Proximal Versus Distal Adductor Canal Blocks for Total Knee Arthroplasty: A Randomized, Double-Blind, Noninferiority Trial.

BACKGROUND AND OBJECTIVES: Adductor canal blocks (ACBs) are associated with improved analgesia, preserved quadriceps strength, and decreased length of hospitalization after total knee arthroplasty (TKA). However, controversy remains regarding the ideal location of a continuous block within the adductor canal, and it remains unclear whether similar clinical benefits are obtained irrespective of block location. In this randomized, double-blind, noninferiority study, we hypothesized that a continuous proximal ACB provides postoperative analgesia that is no worse than a continuous distal ACB. METHODS: Subjects presenting for unilateral TKA were randomized in a 1:1 ratio to either a continuous proximal or distal ACB group. The primary outcome of this noninferiority study was opioid consumption within the first 24 hours following surgery. Secondary outcomes included quadriceps strength, pain scores, distance ambulated, and patient satisfaction. RESULTS: Seventy-three subjects, 36 from the proximal group and 37 from the distal group, completed the study per protocol. The intention-to-treat analysis demonstrated a cumulative mean intravenous morphine equivalent consumption difference between the proximal and distal groups of -7.2 mg (95% confidence interval, -14.8 to 0.4; P < 0.001), demonstrating noninferiority of the proximal approach. The per-protocol analysis yielded similar results: -6.2 mg (95% confidence interval, -14.1 to 1.6; P < 0.001). No secondary outcomes showed statistically significant differences between the proximal and distal groups. CONCLUSIONS: This study demonstrates that a continuous proximal ACB offers noninferior postoperative analgesia compared with a distal continuous ACB in the first 24 hours after TKA. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT02701114).

A Double-Blind Randomized Comparison of Continuous Interscalene, Supraclavicular, and Suprascapular Blocks for Total Shoulder Arthroplasty.

BACKGROUND AND OBJECTIVES: Continuous brachial plexus blocks at the interscalene level are associated with known diaphragm dysfunction from phrenic nerve paresis. More distal blocks along the brachial plexus may provide postsurgical analgesia while potentially having less effect on diaphragm function. Continuous interscalene, continuous supraclavicular, and continuous suprascapular nerve blocks were evaluated for respiratory function and analgesia after total shoulder arthroplasty. METHODS: After ethics board approval, subjects presenting for total shoulder arthroplasty were planned for randomization in a 1:1:1 ratio of a continuous interscalene, supraclavicular, or suprascapular block. The primary outcome was the assessment of vital capacity after 24 hours of continuous nerve block infusion (6 mL/h; 0.2% ropivacaine), without an initial bolus of local anesthetic during catheter placement. Additional outcomes included diaphragm excursion, pain scores, opioid consumption, and adverse effects. RESULTS: Seventy-five subjects, 25 per group, completed the study. At 24 hours of continuous infusion only (no initial block bolus), the mean vital capacity reduction in the continuous interscalene control group was 991 mL (95% confidence interval [CI], 820-1162). Compared to the interscalene group, the continuous supraclavicular group had a mean vital capacity reduction of 803 mL (95% CI, 616-991; P = 0.322). The continuous suprascapular group had a significantly improved mean vital capacity reduction of 464 mL (95% CI, 289-639; P < 0.001) when similarly compared against the interscalene group. A relative compromise in ultrasound-measured diaphragm excursion was identified in the interscalene group compared to both the supraclavicular group (P = 0.012) and the suprascapular group (P < 0.001). Mean pain scores on an 11-point scale (2.2, 1.6, and 2.6) and 24-hour opioid consumption (13.8 mg, 9.9 mg, and 21.8 mg) for groups interscalene, supraclavicular, and suprascapular, respectively, did not show statistically significant differences. Less adverse effects (Horner syndrome, dyspnea, and hoarseness) were noted in the suprascapular group when compared with the interscalene group (P = 0.002). CONCLUSIONS: A continuous suprascapular block may be a useful analgesic alternative to the interscalene or supraclavicular approaches when the preservation of lung function is a priority after shoulder replacement surgery.

Evaluation of Ultrasound-Assisted Thoracic Epidural Placement in Patients Undergoing Upper Abdominal and Thoracic Surgery: A Randomized, Double-Blind Study.

BACKGROUND AND OBJECTIVES: The placement of thoracic epidurals can be technically challenging and requires a thorough understanding of neuraxial anatomy. Although ultrasound imaging of the thoracic spine has been described, no outcome studies on the use of this imaging have been performed. We evaluated whether preprocedural ultrasound of the thoracic spine would facilitate the process of epidural catheterization. METHODS: Subjects undergoing thoracic or upper abdominal surgery with planned thoracic epidural placement at T10 or higher were enrolled in this randomized double-blind study. Subjects were allocated into 1 of 2 groups for preoperative epidural placement: ultrasound guidance (group US) or palpation (group Palp). Subjects randomized to group US had a preprocedural ultrasound examination to identify pertinent spinal anatomy and make appropriate marks on the skin identifying midline and interlaminar spaces for targeted Tuohy needle insertion. Subjects in group Palp had a skin marking performed by palpation alone. Using the skin markings, all epidurals were performed using a loss of resistance to saline technique. Block levels were assessed with ice and pain scores obtained by a blinded nurse in the postanesthesia care unit. The primary outcome was procedural time from needle insertion to loss of resistance in the epidural space. RESULTS: Seventy subjects were recruited and completed the study protocol. The median time for epidural needle placement to achieve loss of resistance in group US and group Palp was 188.5 seconds (interquartile range [IQR], 79.0-515.0) and 242.0 seconds (IQR, 87.0-627.0), respectively (P = 0.188). Using ultrasound to mark the skin overlying the targeted epidural space took a median time of 85 seconds (IQR, 69-113) for group US and 35 seconds (IQR, 27-51) for group Palp (P < 0.001). The number of needle passes was not significantly different between the 2 groups (P = 0.31). The use of ultrasound assistance resulted in a decreased number of needle skin punctures to achieve loss of resistance (P = 0.005). Mean pain scores after surgery were lower in group US compared to group Palp: 3.0 versus 4.7, respectively (P = 0.015). CONCLUSIONS: This is the first randomized study to evaluate the efficacy of preprocedural ultrasound marking for placement of thoracic epidural catheters. We observed that preprocedural ultrasound did not significantly reduce the time required to identify the thoracic epidural space via loss of resistance. CLINICAL TRIALS REGISTRATION: NCT02785055 (https://clinicaltrials.gov/).

Continuous ambulatory adductor canal catheters for patients undergoing knee arthroplasty surgery.

STUDY OBJECTIVE: To determine after knee arthroplasty surgery the feasibility of discharging patients home on postoperative day 1 with continuous adductor canal blocks. DESIGN: Retrospective case series. SETTING: Outpatient setting after hospital discharge. PATIENTS: Patients undergoing knee arthroplasty surgery from October 2013 to August 2014. INTERVENTIONS: All patients received continuous adductor canal catheters for postoperative analgesia and were discharged to home on postoperative day 1. Continuous catheters were intended to remain intact in the ambulatory setting through postoperative day 3. MEASUREMENTS: Data obtained included demographic information, duration of hospital stay, resting and active pain scores, opioid utilization, opioid-induced adverse effects, complications relating to the perineural catheter, and hospital readmissions. MAIN RESULTS: Sixty-nine of 582 patients (11.9%) were discharged to home on postoperative day 1. The median numerical pain score after discharge with a continuous adductor canal block was ≤2 at rest and ≤4 with activity. After block discontinuation on postoperative day 4, median pain scores were the same. No patients reported any unintentional catheter dislodgements, falls, or dysesthesias. There were no readmissions of any patient in this cohort within 90 days of surgery. CONCLUSIONS: Ambulatory adductor canal catheters are a feasible analgesic modality after knee arthroplasty surgery as pain scores remained low and adverse events were minimal.

Neural Network Prediction of ICU Length of Stay Following Cardiac Surgery Based on Pre-Incision Variables.

BACKGROUND: Advanced predictive analytical techniques are being increasingly applied to clinical risk assessment. This study compared a neural network model to several other models in predicting the length of stay (LOS) in the cardiac surgical intensive care unit (ICU) based on pre-incision patient characteristics. METHODS: Thirty six variables collected from 185 cardiac surgical patients were analyzed for contribution to ICU LOS. The Automatic Linear Modeling (ALM) module of IBM-SPSS software identified 8 factors with statistically significant associations with ICU LOS; these factors were also analyzed with the Artificial Neural Network (ANN) module of the same software. The weighted contributions of each factor ("trained" data) were then applied to data for a "new" patient to predict ICU LOS for that individual. RESULTS: Factors identified in the ALM model were: use of an intra-aortic balloon pump; O2 delivery index; age; use of positive cardiac inotropic agents; hematocrit; serum creatinine ≥ 1.3 mg/deciliter; gender; arterial pCO2. The r2 value for ALM prediction of ICU LOS in the initial (training) model was 0.356, p <0.0001. Cross validation in prediction of a "new" patient yielded r2 = 0.200, p <0.0001. The same 8 factors analyzed with ANN yielded a training prediction r2 of 0.535 (p <0.0001) and a cross validation prediction r2 of 0.410, p <0.0001. Two additional predictive algorithms were studied, but they had lower prediction accuracies. Our validated neural network model identified the upper quartile of ICU LOS with an odds ratio of 9.8(p <0.0001). CONCLUSIONS: ANN demonstrated a 2-fold greater accuracy than ALM in prediction of observed ICU LOS. This greater accuracy would be presumed to result from the capacity of ANN to capture nonlinear effects and higher order interactions. Predictive modeling may be of value in early anticipation of risks of post-operative morbidity and utilization of ICU facilities.

A randomized crossover study comparing a novel needle guidance technology for simulated internal jugular vein cannulation.

BACKGROUND: Despite ultrasound guidance for central line placement, complications persist, as exact needle location is often difficult to confirm with standard two-dimension ultrasound. A novel real-time needle guidance technology has recently become available (eZono, Germany) that tracks the needle during insertion. This randomized, blinded, crossover study examined whether this needle guidance technology improved cannulation of a simulated internal jugular (IJ) vein in an ultrasound phantom. METHODS: One hundred physicians were randomized to place a standard needle in an ultrasound neck phantom with or without the needle guidance system. Video cameras were placed externally and within the lumens of the vessels to record needle location in real time. The primary outcome measured was the rate of posterior wall puncture. Secondary outcomes included number of carotid artery punctures, number of needle passes, final needle position, time to cannulation, and comfort level with this new technology. RESULTS: The incidence of posterior vessel wall puncture without and with needle guidance was 49 and 13%, respectively (P < 0.001, odds ratio [OR] = 7.33 [3.44 to 15.61]). The rate of carotid artery puncture was higher without needle navigation technology than with needle navigation 21 versus 2%, respectively (P = 0.001, OR = 12.97 [2.89 to 58.18]). Final needle tip position being located within the lumen of the IJ was 97% accurate with the navigation technology and 76% accurate with standard ultrasound (P < 0.001, OR = 10.42 [2.76 to 40.0]). Average time for successful vessel cannulation was 1.37 times longer without guidance technology. CONCLUSION: This real-time needle guidance technology (eZono) shows significant improvement in needle accuracy and cannulation time during simulated IJ vein puncture.

Fluoroscopic evaluation of contrast distribution within the adductor canal.

BACKGROUND AND OBJECTIVES: This case series assesses the in vivo spread of contrast within the adductor canal in subjects who recently underwent a total knee arthroplasty. A previous analysis of profound leg weakness with a continuous adductor canal revealed contrast spread from the adductor canal to the femoral triangle with as little as 2 mL of volume. METHODS: We enrolled 10 American Society of Anesthesiologists class II-III subjects. Maximum voluntary isometric contraction was measured to assess quadriceps strength before and after surgery. Contrast was then injected continuously via electronic pump into the adductor canal, and fluoroscopy was used to capture images after 1-mL increments. For analysis, the femur was divided into 8 equidistant sectors between the lesser trochanter and medial epicondyle. RESULTS: Contrast did not reach the level of the lesser trochanter or the medial epicondyle of the femur in any subject. The greatest spread after 5 mL of contrast was 4 sectors. Sixty percent of subjects had contrast spread within either the same sector as the catheter tip or 1 sector distally. No subjects demonstrated additional proximal spread of contrast after 4 mL. CONCLUSIONS: This study reveals that in vivo continuous infusions within the adductor canal spread in both a cephalad and caudad direction in limited fashion. Although a previous report described proximal spread of injectate to the level of the common femoral nerve, this event is infrequent.