Diaphragmatic Dysfunction After Ultrasound-guided Supraclavicular Block With Single or Double Injection Technique

Nova Scotia Health Authority

Overview

The investigators plan to determine the incidence of hemi-diaphragmatic paresis (HDP) with two commonly used techniques of supraclavicular nerve block, the single and double injection techniques. It is our hypothesis that a double injection peripheral nerve block technique will increase the risk of HDP when compared to a single injection technique.

The investigators will perform a prospective, blinded, randomized controlled trial to assess the two methods of supraclavicular block (single and double injection), and the resultant incidence of temporary diaphragm dysfunction, or hemi-diaphragmatic paresis (HDP) will be measured with ultrasound. Patients having forearm or hand surgery will be asked by the attending anesthesiologist if they will agree to be approached by someone from the research team for consent and possible inclusion in the study. This will be done in the anesthesia preoperative assessment clinic, or in the pre-op area on the day of surgery (if a patient was not seen in clinic). Once consented, all patients in the study will have baseline measurements of their sensation and movement of the arm for surgery, as well as an ultrasound examination of the movement of the diaphragm. Patients will then be randomized to either the single or double injection supraclavicular nerve block. The blocks will be performed by attending anesthesiologists with experience in regional anesthesia, or by residents and fellows under the direct supervision of such anesthesiologists.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

OTHER

Masking

DOUBLE

Conditions

Anesthesia

Interventions

Single injection supraclavicular nerve blockPROCEDURE

The ultrasound probe will be applied in a sterile fashion in the supraclavicular fossa to obtain a short-axis view of the subclavian artery. A 22G, 50mm Echogenic Stimuplex needle will be advanced in-plane with respect to the image, and the needle tip will be advanced to the junction of the first rib and subclavian artery. Ultrasound cineloops will be kept of all nerve block procedures. 30 milliliters of mepivacaine 1.5% will be injected incrementally in 5ml boluses at this location looking for spread of local anesthetic under and medial to the subclavian artery. The needle may be slightly repositioned to improve the distribution of the injectate at the discretion of the attending anesthesiologist.

Double injection supraclavicular nerve blockPROCEDURE

The ultrasound probe will be applied in a sterile fashion in the supraclavicular fossa to obtain a short-axis view of the subclavian artery. A 22G, 50mm Echogenic Stimuplex needle will be advanced in-plane with respect to the image, and the needle tip will be advanced to the junction of the first rib and subclavian artery. Ultrasound cineloops will be kept of all nerve block procedures. 15 milliliters of mepivacaine 1.5% will be injected incrementally at the same, above-mentioned location. The needle will then be redirected to the superolateral aspect of the brachial plexus, and an additional 15ml will be injected here. Again, the needle may slightly repositioned at the discretion of the attending anesthesiologist in order to obtain adequate spread.

Eligibility

Sex: ALLMin age: 18 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Patients presenting for unilateral upper extremity surgery below the level of the elbow (the forearm or hand) who are having a regional block for anesthesia * Patient must be over 18 years old * Weight greater than 50kg * English speaking * Be available to be contacted by phone on post-operative day 1 * ASA physical status 1-3 * BMI under 35 kg/m2 Exclusion Criteria: * Inability to consent to study participation * Pre-existing neuromuscular disease or severe neurological dysfunction * Severe coagulopathy * Severe obstructive or restrictive lung disease * Pregnancy * Prior surgery in the supraclavicular region * Allergy to medications used in the study * Known diaphragmatic dysfunction of either diaphragm * Inability to visualize the diaphragm with ultrasound on the side of the surgical procedure * Highly opioid-tolerant patient (\>40mg of morphine PO or equivalent per day for \>1month) * Patient requests a general anesthesia technique * Attending anesthesiologist preference for alternate anesthetic technique * Surgeon or attending anesthesiologist request for a different anesthesia technique * Current involvement in another study

Outcomes

Primary Outcomes

Incidence of Hemidiaphragmatic paresis (HDP) by diaphragmatic thickening

Ultrasound measurement of diaphragmatic thickening

Time frame: Relative change in ultrasound assessment of diaphragmatic thickening (Baseline vs 30 min after supraclavicular block)

Secondary Outcomes

Onset time of sensory block

Sensation of the terminal peripheral nerves of the upper extremity will be assessed by a single observer blinded to the technique for the musculocutaneous, median, radial, ulnar and the medial antebrachial cutaneous nerves. Sensory assessments will be done using a blunt needle and the response will be assessed on a 3-point scale using the contralateral limb as a control: 0 = normal sensation, 1 = hypoesthesia, and 2 = anesthesia. A composite score will be created for each time point.

Time frame: Baseline, 5, 10, 15, 20, 25, and 30 minutes after block

Onset time of motor block

Motor blockade of the musculocutaneous, radial, median, and ulnar nerves will be evaluated by elbow flexion, thumb abduction, thumb opposition, and thumb adduction, respectively. Motor blockade will be graded on a 3-point scale: 0 = normal strength, 1 = weakness relative to the contralateral side, and 2 = complete paralysis. A composite score will be created for each time point.

Time frame: Baseline, 5, 10, 15, 20, 25, and 30 minutes after block

Bedside spirometry - forced expiratory volume at one second (FEV1)

Relative changes in forced expiratory volume at one second (FEV1) will be compared

Time frame: Relative change in FEV1 (Baseline vs 30 min after supraclavicular block)

Bedside spirometry - forced vital capacity (FVC)

Relative changes in forced vital capacity (FVC) will be compared

Time frame: Relative change in FVC (Baseline vs 30 min after supraclavicular block)

Data from ClinicalTrials.gov

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