A randomized controlled trial evaluating the impact of selective axillary nerve block after arthroscopic subacromial decompression.

BACKGROUND: The sensory innervation of the shoulder is complex and there are variations in the branching patterns of the sensory fibres. Articular branches from the axillary nerve to the subacromial bursa are described in more than 50% of investigated shoulders but the isolated contribution of sensory input from the axillary nerve has never been investigated clinically. We hypothesized that a selective block of the axillary nerve would reduce morphine consumption and pain after arthroscopic subacromial decompression. METHODS: We included 60 patients in a randomized, blinded, placebo-controlled study. Patients were randomized to a preoperative selective ultrasound-guided axillary nerve block with 20 mL ropivacaine (7.5 mg/mL) or 20 mL saline. Primary outcome was intravenous morphine consumption 0-4 h postoperatively. Secondary outcome was postoperative pain evaluated by a visual analogue scale (VAS) score (0-100). RESULTS: We analysed data from 50 patients and found no significant difference in 0-4 h postoperative morphine consumption between the two groups (ropivacaine 14 mg, placebo 18 mg (P = 0.12)). There was a reduction in postoperative pain: VAS 0-4 h (area under the curve) (ropivacaine 135, placebo 182 (P = 0.03)), VAS after 8 h (ropivacaine 9, placebo 20 (P = 0.01)) and VAS after 24 h (ropivacaine 7, placebo 18 (P = 0.04)). Eight out of 19 patients with a successful selective axillary nerve block needed an interscalene brachial plexus escape block. CONCLUSIONS: Selective block of the axillary nerve has some pain relieving effect, but in this setting the effect was unpredictable, variable and far from sufficient in a large proportion of the patients. TRIAL REGISTRATION: ClinicalTrials.gov (NCT01463865). Registered: November 1, 2011.

Pectoral Block Failure May Be Due to Incomplete Coverage of Anatomical Targets: A Dissection Study.

BACKGROUND AND OBJECTIVES: The popularization of ultrasound-guided nerve blocks in cosmetic and reconstructive breast surgery calls for better anatomical understanding of chest wall innervation. When inserting subpectoral implants, pain from pocket dissection, stretching of muscle, and release of costal attachments may be relieved by blocking the pectoral nerves in the interpectoral (IP) space.We describe the variable anatomy of the pectoral nerves in the IP space in order to define the area to be covered for sufficient blockade, based on cadaver dissections. METHODS: Twenty-six fresh cadavers were dissected bilaterally. The number, location, and course of the pectoral nerves were recorded. Distances to surface landmarks (sternum, clavicle, and costae) and ultrasound landmarks (thoracoacromial artery [TAA] and pectoralis minor muscle [Pm]) were recorded. RESULTS: The lateral pectoral nerve and the TAA entered together into the IP space 8.9 cm (range, 8.0-12.0 cm) lateral to the midsternal line. The medial pectoral nerve (MPN) had between 1 and 4 branches that pierced the Pm, and 69% had additional branches lateral to the Pm. The muscle-piercing MPN branches were located 3.8 cm (range, 0.4-8.1 cm) and the lateral MPN branches 5.4 cm (range, 3.0-8.4 cm) from the lateral pectoral nerve. The IP course was 2.6 cm (range, 0.7-6.5 cm). All specimens were asymmetrical in location or number of MPN branches. CONCLUSIONS: The MPN branches that innervate the lower part of the pectoralis major muscle are asymmetrical and variable in location and length; all located in a triangular area easily defined by sonographic landmarks, lateral to the TAA.

Deep neuromuscular blockade and low insufflation pressure during laparoscopic hysterectomy.

INTRODUCTION: Establishment of sufficient muscle relaxation is essential in laparoscopic surgery. During laparoscopy, surgeons can experience abdominal contractions in their patients. Deep neuromuscular block (NMB) has the potential to prevent such episodes. In this study, we explored if deep NMB reduces the incidence of sudden abdominal contractions as compared with standard NMB. METHODS: This was a pre-planned secondary analysis of a randomized, controlled study. A total of 110 patients scheduled for laparoscopic hysterectomy were randomized to either deep NMB and 8 mmHg pneumoperitoneum (deep NMB group) or single-bolus NMB and 12 mmHg pneumoperitoneum (standard NMB group). NMB was established with rocuronium and reversed with sugammadex. Two gynaecologists registered episodes of sudden abdominal contractions, alarms from the insufflator due to increased intraabdominal pressure and incidences with tightness of the abdominal wall. RESULTS: No sudden abdominal contractions were detected in the deep NMB group as compared with 12 episodes in the standard NMB group (p < 0.001). The insufflator alarmed in no versus ten procedures (p = 0.001) in the deep and standard NMB group, respectively. The gynaecologists registered increasing abdominal tensions in no versus eight procedures (p = 0.006) in the deep and standard NMB group, respectively. CONCLUSION: Deep NMB in combination with 8 mmHg pneumoperitoneum prevented sudden abdominal contractions during laparoscopic hysterectomy. FUNDING: This work was funded in part by a research grant from the Investigator Initiated Studies Program of Merck Sharp & Dohme Corp, USA. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp & Dohme Corp. TRIAL REGISTRATION: The study was assigned with EudraCT number 2012-003787-51 and registered with clinicaltrials.gov (NCT01722097).

Postoperative shoulder pain after laparoscopic hysterectomy with deep neuromuscular blockade and low-pressure pneumoperitoneum: A randomised controlled trial.

BACKGROUND: Postoperative shoulder pain remains a significant problem after laparoscopy. Pneumoperitoneum with insufflation of carbon dioxide (CO2) is thought to be the most important cause. Reduction of pneumoperitoneum pressure may, however, compromise surgical visualisation. Recent studies indicate that the use of deep neuromuscular blockade (NMB) improves surgical conditions during a low-pressure pneumoperitoneum (8 mmHg). OBJECTIVE: The aim of this study was to investigate whether low-pressure pneumoperitoneum (8 mmHg) and deep NMB (posttetanic count 0 to 1) compared with standard-pressure pneumoperitoneum (12 mmHg) and moderate NMB (single bolus of rocuronium 0.3 mg kg with spontaneous recovery) would reduce the incidence of shoulder pain and improve recovery after laparoscopic hysterectomy. DESIGN: A randomised, controlled, double-blinded study. SETTING: Private hospital in Denmark. PARTICIPANTS: Ninety-nine patients. INTERVENTIONS: Randomisation to either deep NMB and 8 mmHg pneumoperitoneum (Group 8-Deep) or moderate NMB and 12 mmHg pneumoperitoneum (Group 12-Mod). Pain was assessed on a visual analogue scale (VAS) for 14 postoperative days. MAIN OUTCOME MEASURES: The primary endpoint was the incidence of shoulder pain during 14 postoperative days. Secondary endpoints included area under curve VAS scores for shoulder, abdominal, incisional and overall pain during 4 and 14 postoperative days; opioid consumption; incidence of nausea and vomiting; antiemetic consumption; time to recovery of activities of daily living; length of hospital stay; and duration of surgery. RESULTS: Shoulder pain occurred in 14 of 49 patients (28.6%) in Group 8-Deep compared with 30 of 50 (60%) patients in Group 12-Mod. Absolute risk reduction was 0.31 (95% confidence interval 0.12 to 0.48; P = 0.002). There were no differences in any secondary endpoints including area under the curve for VAS scores. CONCLUSION: Deep NMB and low-pressure pneumoperitoneum (8 mmHg) reduced the incidence of shoulder pain after laparoscopic hysterectomy in comparison to moderate NMB and standard-pressure pneumoperitoneum (12 mmHg). TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT01722097.

Adductor canal block for postoperative pain treatment after revision knee arthroplasty: a blinded, randomized, placebo-controlled study.

BACKGROUND: Revision knee arthroplasty is assumed to be even more painful than primary knee arthroplasty and predominantly performed in chronic pain patients, which challenges postoperative pain treatment. We hypothesized that the adductor canal block, effective for pain relief after primary total knee arthroplasty, may reduce pain during knee flexion (primary endpoint: at 4 h) compared with placebo after revision total knee arthroplasty. Secondary endpoints were pain at rest, morphine consumption and morphine-related side effects. METHODS: We included patients scheduled for revision knee arthroplasty in general anesthesia into this blinded, placebo-controlled, randomized trial. Patients were allocated to an adductor canal block via a catheter with either ropivacaine or placebo; bolus of 0.75% ropivacaine/saline, followed by infusion of 0.2% ropivacaine/saline. Clinicaltrials.gov ID: NCT01191593. RESULTS: We enrolled 36 patients, of which 30 were analyzed. Mean pain scores during knee flexion at 4 h (primary endpoint) were: 52 ± 22 versus 71 ± 25 mm (mean difference 19, 95% CI: 1 to 37, P = 0.04), ropivacaine and placebo group respectively. When calculated as area under the curve (1-8 h/7 h) pain scores were 55 ± 21 versus 69 ± 21 mm during knee flexion (P = 0.11) and 39 ± 18 versus 45 ± 23 mm at rest (P = 0.43), ropivacaine and placebo group respectively. Groups were similar regarding morphine consumption and morphine-related side effects (P > 0.05). CONCLUSIONS: The only statistically significant difference found between groups was in the primary endpoint: pain during knee flexion at 4 h. However, due to a larger than anticipated dropout rate and heterogeneous study population, the study was underpowered. TRIAL REGISTRATION: Clinicaltrials.gov NCT01191593.

Distal infrared thermography and skin temperature after ultrasound-guided interscalene brachial plexus block: a prospective observational study.

BACKGROUND: Increases in skin temperature may be used as an early predictor of the success of interscalene brachial plexus block (IBPB), but we lack detailed information on the thermographic response. OBJECTIVE: To investigate and characterise the thermographic response after IBPBs. DESIGN: Prospective observational study. SETTING: University hospital and private hospital. PATIENTS: Twenty-nine male and 17 female patients scheduled for ambulatory shoulder surgery. Exclusion criteria were age less than 18 years, body weight more than 120 kg and any coagulation abnormality. INTERVENTIONS: Infrared thermographic imaging of the hand before and at 1 min intervals for 30 min after an ultrasound-guided IBPB with 20 ml ropivacaine 7.5 mg ml. Cooling of both hands was performed to standardise measurements. MAIN OUTCOME MEASURES: Thermographic changes in skin temperature on the dorsum of the hand. RESULTS: Forty-four blocks were successful and two were failures. Four thermographic patterns were observed after successful blocks: the increase in skin temperature was restricted to the thumb (n = 5); increase in skin temperature of the thumb and the second digit (n = 11); increase in skin temperature of the thumb, the second and fifth digits (n = 4); and an increase in skin temperature in all parts of the hand (n = 24). All successful blocks demonstrated a significant (P < 0.0001) increase in median (range) of distal skin temperature of the thumb of 6.6°C (0.7 to 17.2) by 30 min, which was already significant (P < 0.0001) by 5 min. By contrast, skin temperature decreased significantly (P < 0.0001) in the hand after failed blocks and in the contra-lateral non-blocked hand by -1.5°C (-6.2 to 4.2). CONCLUSION: Successful IBPB resulted in four thermographic patterns. Skin temperature always increased on the thumb within 30 min and this increase achieved statistical significance at 5 min after the block.

Should dosing of rocuronium in obese patients be based on ideal or corrected body weight?

BACKGROUND: Pharmacokinetic studies in obese patients suggest that dosing of rocuronium should be based on ideal body weight (IBW). This may, however, result in a prolonged onset time or compromised conditions for tracheal intubation. In this study, we compared onset time, conditions for tracheal intubation, and duration of action in obese patients when the intubation dose of rocuronium was based on three different weight corrections. METHODS: Fifty-one obese patients, with a median (range) body mass index of 44 (34-72) kg/m2, scheduled for laparoscopic gastric banding or gastric bypass under propofol-remifentanil anesthesia were randomized into three groups. The patients received rocuronium (0.6 mg/kg) based on IBW (IBW group, n = 17), IBW plus 20% of excess weight (corrected body weight [CBW]20% group, n = 17), or IBW plus 40% of excess weight (CBW40% group, n = 17). Propofol was administered as a bolus of 200 mg and an infusion at 5 mg x kg(-1) x h(-1) and remifentanil was administered at 1.0 microg x kg(-1) x min(-1), both according to CBW40%. Neuromuscular function was monitored with train-of-four nerve stimulation and acceleromyography. The primary end point was duration of action, defined as time to reappearance of the fourth twitch in train-of-four. RESULTS: The median (range) duration of action was 32 (18-49), 38 (25-66), and 42 (24-66) min in the IBW, CBW20%, and CBW40% groups, respectively (P = 0.001 for comparison of the IBW and CBW40% group). There were no significant differences in onset time (85 vs 84 vs 80 s) or in intubation conditions 90 s after administration of rocuronium. CONCLUSIONS: In obese patients undergoing gastric banding or gastric bypass, rocuronium dosed according to IBW provided a shorter duration of action without a significantly prolonged onset time or compromised conditions for tracheal intubation.

Risk factors associated with interdog aggression and shooting phobias among purebred dogs in Denmark.

The prevalence of behaviour problems is reported from a questionnaire study among members of the Danish Kennel Club (DKC). In total, 4359 dog owners were included in the analyses. With logistic regression, we analysed four behaviour problems: dominance towards the owner, interdog dominance aggression, separation anxiety and shooting phobia. Compared to Labrador Retrievers, the following breeds and breed groups had higher odds of being reported to have interdog dominance aggression: Belgian Sheepdogs, Dachshunds, Dalmatians, German Shepherds, Hovawarts, Pinschers, Rottweilers, Scent dogs and Spitz dogs. Poodles, retrieving/flushing dogs, Sheepdogs, Spitz dogs and terriers had higher odds of shooting phobia. The odds of interdog dominance aggression were higher among dogs owned by younger dog owners compared to dogs owned by older dog owners. Dogs living in the capital area of Copenhagen had increased odds of interdog dominance aggression as compared to dogs living in other parts of Denmark. Dogs belonging to owners with limited knowledge of the breed before acquiring the dog had higher odds of interdog dominance aggression. Dogs attending obedience training classes had reduced odds of shooting phobia. Dogs belonging to dog breeders had reduced odds of being reported to have the investigated behaviour problems.