Bryan Chung

Bupivacaine digital blocks: how long is the pain relief and temperature elevation?

Background: The goals of this study are threefold: (1) to determine what effect epinephrine has on the duration of bupivacaine finger block anesthesia; (2) to see whether the duration of action of bupivacaine on digital pain relief is the same duration as numbness to touch/pressure; and (3) to assess the fingertip temperature changes that result from bupivacaine digital blocks. Methods: The ring fingers of both hands of 44 volunteers were randomized to injection of bupivacaine with or without 1:200,000 epinephrine. The durations of time for digits to return to normal pain, touch, pressure sensation, and fingertip temperature were measured and recorded. Results: There were three main findings: (1) the pain block of bupivacaine lasts only half as long (15 hours) as the return to normal sensation (30 hours); (2) the effect of adding epinephrine to bupivacaine prolongs the duration of pain relief in a finger block for only an additional 1.5 hours; (3) in addition to pain relief, bupivacaine finger blocks cause fingertip hyperemia with consistent significant fingertip temperature elevation that lasts 15 hours. Conclusions: The duration of bupivacaine pain relief is the clinically important factor that needs to be reported in bupivacaine trials. Patients should be informed that the return of pain will occur much sooner than the return of normal sensation. Adding epinephrine to bupivacaine does not add a clinically significant length of time to pain relief. Bupivacaine finger blocks provide prolonged hyperemia and pain block to fingertips, which may be useful in the treatment of acute frostbite. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, I.

The hyperthermic effect of a distal volar forearm nerve block: a possible treatment of acute digital frostbite injuries?

Background: The authors have observed that carpal tunnel surgery nerve blocks consisting of subfascial distal volar forearm injection of 10 cc of 1% lidocaine with epinephrine result in fingers that appear hyperemic, warm, and numb in both median and ulnar nerve distributions. The purposes of this study were to (1) determine whether forearm nerve blocks in patients undergoing carpal tunnel releases result in an objective increase in finger temperature, and (2) document the location and duration of finger anesthesia. Methods: Thirty-nine patients undergoing unilateral carpal tunnel release were studied prospectively. An infrared thermometer was used to measure the temperature in the fingers of operative and nonoperative hands before and after injection of local anesthetic. The distal volar forearm block was performed using 10 cc of 1% lidocaine with 1:100,000 epinephrine deep to the forearm fascia between the median and ulnar nerves 1 cm proximal to the wrist crease. Before and after carpal tunnel release, bilateral finger temperatures were measured at hourly intervals. Statistical analysis included a one-sample test of proportions. Results: The finger temperature of the operative hand was significantly warmer than the unoperated hand over the first 2 hours after the nerve block. Seventy-four percent of patients had a statistically significant increase in temperature. On average, the nerve block lasted 6.27 hours in the median nerve distribution and 5.78 hours in the ulnar nerve distribution. Conclusions: Forearm nerve blocks produce a chemical sympathectomy that provides a significant increase in skin temperature as a result of vasodilatation in most patients. They also provide prolonged finger numbness. This could be of clinical benefit in patients with acute finger frostbite injuries.

Reliability and internal validity of the michigan hand questionnaire.

BackgroundThe Michigan Hand Outcomes Questionnaire (MHQ) remains one of very few to be based on validated and systematic methods in its creation. However, test-retest reliability and internal validity have not been appropriately investigated in any other English-speaking population outside the original development sample. The objective of this study is to examine the reliability and internal validity of the MHQ in a Canadian population. MethodsAll patients with a clinical hand problem but no hand immobilization who attended our Plastic Surgery Clinic were invited to participate in this study. Patients were asked to complete the MHQ, and then contacted to arrange for completion of the MHQ a second time. Internal validity was estimated using Cronbach alpha. Reliability was estimated using the method of Bland and Altman, and intraclass correlation coefficients. Correlation analysis between score differences and time between tests was performed. ResultsFull versions of the MHQ were completed by 116 participants on their initial visit, while only 77 participants completed a second MHQ. Cronbach alpha ranged from 0.84 to 0.95 for the MHQ subscales. Intraclass-correlation coefficients ranged from 0.71 to 0.84 for the subscales. The magnitude of the limits of agreement for the subscales ranged from 13.8 to 26.2. The difference in scores between the first and second tests was not related to the time between tests. ConclusionThe high values of Cronbach alpha indicate high internal validity, but that there may be redundancy between items in the MHQ, which could be eliminated without losing information. Reliability of the MHQ is considered moderate. The limits of agreement are considered wide, indicating potential issues with respect to interpretation of a change in score between 2 administrations of the MHQ.

The effect of buffering on pain and duration of local anesthetic in the face: A double-blind, randomized controlled trial

BACKGROUND The acidity of lidocaine preparations is believed to contribute to the pain of local anesthetic injection. OBJECTIVE To investigate the effect of buffering lidocaine on the pain of injection and duration of anesthetic effect. METHODS A double-blind, randomized trial involving 44 healthy volunteers was conducted. The upper lip was injected with a solution of: lidocaine 1% (Xylocaine, AstraZeneca, Canada, Inc) with epinephrine; and lidocaine 1% with epinephrine and 8.4% sodium bicarbonate. Volunteers reported pain of injection and duration of anesthetic effect. RESULTS Twenty-six participants found the unbuffered solution to be more painful. Fifteen participants found the buffered solution to be more painful; the difference was not statistically significant. Twenty-one volunteers reported duration of anesthetic effect. The buffered solution provided longer anesthetic effect than the unbuffered solution (P=0.004). CONCLUSION Although buffering increased the duration of lidocaines anesthetic effect in this particular model, a decrease in the pain of the injection was not demonstrated, likely due to limitations of the study.

Confirmatory factor analysis of the Michigan Hand Questionnaire.

BackgroundWhen the Michigan Hand Questionnaire (MHQ) was originally developed, an exploratory factor analysis (EFA) was used to reduce the originally large number of generated items to the 63 items currently present on the questionnaire. Confirmation of the implied factor model of the existing MHQ has never been performed. The objective of this study was to confirm the factor model used to create the existing MHQ, and to possibly shorten the existing MHQ using factor analysis. MethodsPatients attending the Plastic Surgery Clinic at the QEII Health Sciences Centre with a hand complaint were asked to complete the MHQ. Confirmatory factor analysis was performed to explore the implied factor structure of the original EFA and to examine the interplay between the MHQ subscales. Further item-reduction was performed using clinically guided decisions as well as factor analysis-guided statistics. ResultsInitial confirmatory factor analysis showed that original EFA model does not optimally explain the relationships between items in the existing MHQ and their corresponding factors. Our abbreviated model of the MHQ consists of 23 items, and performed more favorably in all goodness-of-fit parameters than the original 63-item questionnaire. ConclusionsThe factor model of the existing MHQ does not fully take advantage of the relationship between items in the MHQ and the proposed factors. This study proposes a shortened version of the MHQ that more accurately reflects hand health as well as a factor-based interpretation of the subscales that takes interdependent relationships into account.

Discussion: Sensory reconstruction of a finger pulp defect using a dorsal homodigital island flap.

T goals of finger tip pulp reconstruction can generally be thought of as threefold: (1) to provide adequate tissue coverage of underlying bone and soft-tissue structures, (2) to provide a sensate finger tip for functional activities, and (3) to minimize donor-site morbidity. Although there have been many descriptions of reconstructive flap or graft techniques to reconstruct finger tip pulp defects, restoring neurosensory function and providing adequate tissue coverage has been a particular challenge. Most techniques presented to date have been able to address, at most, two of the three aforementioned goals, with the additional problem of most homodigital techniques being restricted by the size of the defect. This article, entitled “Sensory Reconstruction of a Finger Pulp Defect Using a Dorsal Homodigital Island Flap,” presents an additional tool for management of moderate to large finger tip defects. Such a single-stage approach appears to be effective in structural and functional restoration, with minimal complications. By using the clarified anatomy and finer dissection of the distal dorsal branch of the digital artery, the authors have minimized donor-site scarring. This is a refinement as compared with similar techniques described by Takeishi et al.1 and Li and Cui.2 However, there are several points that warrant further discussion. First, as with all studies in which statistical significance testing is performed, the interpretation of a “statistically significant” result within the context of whether the observed differences are clinically relevant is of paramount importance. The authors observed a statistically significant difference in both two-point discrimination and Semmes-Weinstein monofilament testing; however, it is difficult to interpret these results without additional context. It is not clear as to how the sensory outcomes compared with the contralateral uninjured digit, ipsilateral uninjured digits, or the presurgical donor site. A comparison with these three control sites would allow the reader to determine whether the observed statistical difference has clinical relevance. Second, with respect to the statistical testing itself, the authors generally performed appropriate testing. However, on examination of the values reported in Table 2 for two-point discrimination, the distribution is clearly skewed to 5 mm. Although the t test is generally considered fairly robust, this robustness against violations of its assumptions only holds in large sample sizes. Similarly, the data type in the Semmes-Weinstein test would not generally be considered as continuous, but rather ordinal, as not all values between monofilament sizes are possible. This discrepancy calls into question whether the differences observed between the new reconstructive technique and the conventional technique could have been observed by chance alone. Third, although objective sensory testing is generally considered the measurement of least bias when conducted consistently and appropriately, sensation remains primarily a subjective quality. Satisfaction with the new reconstructive technique was measured with the Michigan Hand Outcomes Questionnaire; however, the results of only a single question were reported. It is not known whether the other items on the Michigan Hand Outcomes Questionnaire concerning both self-rated hand function and self-rated sensation behaved in a similar manner as the satisfaction item. Fourth, one lingering unanswered issue in this technique and similar ones as reported by Lai et al.3 is the anatomy of venous return. Although the authors do succeed in clarifying the anatomy of the dorsal branch of the proper digital artery,

Relative Motion Flexion Splinting for Flexor Tendon Lacerations: Proof of Concept:

Background: The principle of relative motion has allowed patients to regain a higher degree of hand function, while protecting extensor tendon repairs. The purpose of this study was to determine whether the principle of relative motion could be a viable method to protect a flexor tendon repair. Methods: Four fresh-frozen cadaver arms were each mounted on a testing apparatus (wrist in 30° of extension, metacarpophalangeal [MCP] joints blocked to 70°-80°). A minimum of 11 N was used to cyclically load the flexor digitorum profundus and extensor digitorum communis tendons to maximum allowable flexion and extension for 25 cycles. Measurements of elongation of the tendons were obtained through the use of differential variable reluctance transducers. Testing was performed in both intact and repaired (single 6-0 nylon suture) middle finger tendons (zone 3) with and without a relative motion flexion splint (RMFS), which placed the affected finger in 15° to 25° of relative flexion at the MCP joint. Results: In all 4 hands, elongation was restricted to less than 1.3 mm in repaired tendon in the RMFS compared with elongation >2 mm in the nonsplinted condition. Average elongation was 0.86 mm (SD = 0.45). Visual examination of the tendons demonstrated no gapping with the use of the RMFS in any of the hands. All repairs had suture breakage and repair rupture without the RMFS. Conclusions: This study demonstrates that the RMFS decreases elongation and eliminates tendon-repair gapping after flexion/extension cycling in a cadaver model. It provides proof of concept that the RMFS may be a viable protective mechanism for flexor tendon repairs in zone 3.

Factors influencing prioritization for carpal tunnel syndrome consultation.

BACKGROUND In a socialized medicine model, prioritization of referrals for specialist consultation is highly important in the distribution of heath care. For high-burden diseases, such as carpal tunnel syndrome (CTS), the factors that influence prioritization are not well understood. OBJECTIVE To determine the factors that influence the prioritization of referrals for CTS consultation by plastic surgeons in Canada. METHODS All members of the Canadian Society of Plastic Surgery with e-mail addresses were invited to participate in an online survey regarding the method by which they prioritize referrals for CTS. RESULTS Forty per cent of invited members completed the survey (150 surgeons). Of these, 118 (79%) stated that they performed CTS surgery. The majority of respondents who performed CTS surgery prioritized their consultation list chronologically (77%). Factors that would alter the chronological order or prioritization included subsequent contact by the referring physician (24%); personal relationship with the patient (16%); and specific information in the referral letter (15%), which usually involved symptom severity or electromyography findings. Sixty-six per cent of plastic surgeons stated that there was no conscious decision on how they came to choose the method of prioritization they used for referrals regarding CTS. DISCUSSION The majority of plastic surgeons in Canada prioritize referrals for consultation on CTS chronologically. A minority of respondents reported reassigning priority based on clinical severity. The rationale for the methods by which Canadian Society of Plastic Surgery members prioritize these referrals is poorly understood. Further study on developing evidence-based prioritization methods may be useful in assisting surgeons and their patients in outcome-based decisions.

Pre- and/or Postsurgical Administration of Estradiol Benzoate Increases Rates of Skin Flap Viability in Female Rats

Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of