The Study of Regional Hemodynamic Changes After Specific Brachial Plexus Block by Ultrasound Guidance

Phase 1

Completed

Conditions: Upper Limb Nerve Block

Interventions: Procedure: specific nerve block
Drug: ropivacaine

Registration Number: NCT02139982

Lead Sponsor: Wenzhou Medical University

Brief Summary: Phase 1 Sympathetic block leads to vasodilatation and increases in blood flow. However, regional hemodynamic changes of radial and ulnar artery after specific nerve block of brachial plexus remains unclear. The aim of the study is to assess the effect of specific nerve block of brachial plexus on hemodynamics of upper extremity, and provides evidence for further research in patient undergoing microvascular surgery.

Phase 2 There is no literature about dose-finding studies of sympathetic block after brachial plexus block. Little is known regarding the relationship between concentration of local anaesthetic and vasodilation of upper extremity. The aim of this randomized, double-blind, prospective dose-response study is to determine the ED50 and ED95 of ropivacaine in sympathetic block of upper extremity after supraclavicular block

Detailed Description: Phase 1 Brachial plexus block (BPB) is a widely used regional anesthetic technique for upper limb surgery. The effect of sympathetic block of BPB can leads to vasodilatation and increase blood flow and skin temperature in the ipsilateral upper limb. At the level of the axillary region, the sympathetic nerves innervating the radial and ulnar artery travel with the brachial plexus, but it is unclear which specific nerve: musculocutaneous, radial, ulnar, and median innervates radial or ulnar artery. Radial and ulnar artery and their branches are common donor or recipient vessels in the vascular reconstruction surgery and their hemodynamic changes may affect the blood flow of vascular anastomoses in vascular reconstruction. Sometimes, brachial plexus could be partially blocked intentionally or unintentionally, with the resultant regional hemodynamic changes unclear.

As the use of ultrasound guided peripheral nerve block getting increasingly popular, peripheral nerve can be blocked visually, with good accuracy and ease. It has made specific nerve block in the axillary region possible. Can specific nerve block increase the blood flow of target artery (radial or ulnar artery) and benefit microvascular surgery, or will it decrease the blood flow in other arteries and have a negative impact on microvascular surgery? In this study, the investigators will measure the hemodynamic changes of radial and ulnar artery after performing specific nerve blocks of the musculocutaneous, radial, ulnar, or median nerves respectively in patients without vascular disease. The aim is to assess the effect of specific nerve block on hemodynamics of upper extremity, and provided evidence for further research in patients undergoing microvascular surgery.

The subjects of study are patients undergoing upper extremity operation. All patients will be randomized into 4 groups according to the specific nerve block (SNB) of brachial plexus: group MC (musculocutaneous), group UL (ulnar), group RA (radial) and group ME (median). Patients are randomised to the four groups by random number(generated by computer) in sealed envelopes. Sample randomization will be done in four groups by random-number using sealed envelopes. Each patient will receive allocated SNB of brachial plexus (musculocutaneous, radial, ulnar, or median) followed by Axillary brachial plexus block successively using ultrasound guidance combined neurostimulation. All nerve blocks will be performed by a single dedicated anesthetist. A second investigator, who is blinded to the protocol and patient allocation, will perform the measurements.

Sensory blockade will be assessed by pinprick sensation (22 G needle) and compare with the opposite forearm/hand for normal, hypoesthesia or no sensation. Success of SNB is defined as only loss of sensation in the cutaneous distribution of the specific nerve (musculocutaneous, ulnar, radial, or median nerves) at 30min after SNB. If hypoesthesia or no sensation is detected in the innervation areas of any other nerve, the patient will be excluded. Success of BPB is defined as the absence of sensation to in all innervation areas of above four nerves 30min after the BPB.

Measurement of hemodynamic parameters The ulnar artery and radial artery is located at 1 cm proximal to the ulnar or radial styloid process. Specific points will be located with skin marker to provide consistency with all measurements taken. Hemodynamic parameters will is measured by Pulsed-wave Doppler (PWD) ultrasound. The probe will be placed on the ventral wrist parallel to the long axis of the forearm without undue pressure on the artery during the PWD measurements. The volume gate will be positioned in the center of the arterial lumen, and the size of the gate will be 1/3 lumen of the artery. The angle of insonation is adjusted and maintained at 50-60 degrees. Once a desired PWD spectral waveform is achieved, the arterial hemodynamic parameters will be recorded.

Phase 2 The subjects of study are patients undergoing upper extremity operation under supraclavicular brachial plexus block. All patients will be randomly assigned to receive 30ml ropivacaine in concentrations of 0.125%, 0.2%, 0.25%, 0.375%, 0.5%, or 0.75%. Patients are randomised to the four groups by random number(generated by computer) in sealed envelopes. All nerve blocks were performed by a single dedicated anaesthetist who remains blinded to the concentration of ropivacaine.

A second investigator, who is blinded to the protocol and patient allocation, will perform the measurements. Another investigator, who is not present during the conduct of the BPB and blinded to the concentration of ropivacaine used will assess each blockade. Patient are also blinded.

The brachial plexus will be visualized using a high-frequency linear ultrasound transducer in the supraclavicular fossa. After skin disinfection and infiltrating with 1% lidocaine, nerve stimulation needle will be inserted using in-line technique,and advanced among the divisions of brachial plexus with electric impulses (2 Hz, 0.3mA, 0.1 ms) of nerve stimulator. If visible contraction of the innervated muscle is elicited, the needle will be withdrawn slowly until the corresponding muscle contraction disappears to avoid intrafascicular puncture. The local anesthetic will be injected at three locations: adjacent to the superficial divisions of the plexus, adjacent to the middle divisions and inferior divisions. The proportion of the volume injected in each area is at the discretion of the expert operator according to the spread of local anesthetic.

The efficacy of the block will be assessed by pinprick sensation (22 G needle) and compared with the opposite arm/hand for normal, hypoesthesia or no sensation. For patients with an ineffective block, supplementary local anesthesia will be administered according to the distribution of the block and site of surgery after measurement. If the patient experienced any pain during surgery, supplementary analgesia, sedation, or general anesthesia will be administered as required.

Patient's arm is in supination. The brachial artery will be located in 2 cm proximal to the antecubital fossa. Hemodynamic Parameters will be measured by Pulsed-wave Doppler(PWD) ultrasound. The probe will be parallel the long axis of the arm without undue pressure on the artery during the PWD measurements. The volume gate will be positioned in the center of the arterial lumen, and the size of the gate will be 1/3 lumen of the artery. The angle of insonation will be adjusted and maintained at 50-60 degrees. Once a desired PWD spectral waveform is achieved, the arterial hemodynamic parameters will be recorded. The cross-sectional area (CSA) of the artery will be assessed with B-mode imaging. Probe should be as perpendicular as possible to the long axis of the artery to obtain as round an arterial section as possible. The image at end diastole will be chosen and measured with the cine loop.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 110

Inclusion Criteria

American Society of Anesthesiologist physical status I-III patients
aged 18-70 yr
weighing 40-80 kg

Exclusion Criteria

infection at the site of needle insertion
coagulopathy
international normalized ratio >1.4
platelet count <80×109 litre-1
allergy to local anaesthetics
peripheral neurological disease
peripheral vascular disease
patients do not agree to sign the informed consent.

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
group MC(phase 1)	specific nerve block	specific nerve block:musculocutaneous nerve block
group UL( phase 1)	specific nerve block	specific nerve block:ulnar nerve block
group RA (phase 1)	specific nerve block	specific nerve block:radial nerve block
group ME (phase 1)	specific nerve block	specific nerve block:median nerve block
group B(phase 2)	ropivacaine	30ml ropivacaine 0.2%
group A(phase 2)	ropivacaine	30ml ropivacaine 0.125%
group E(phase 2)	ropivacaine	30ml ropivacaine 0.5%
group C(phase 2)	ropivacaine	30ml ropivacaine 0.25%
group D(phase 2)	ropivacaine	30ml ropivacaine 0.375%
group F(phase 2)	ropivacaine	30ml ropivacaine 0.75%

Primary Outcome Measures

Name	Time	Method
Changes in Hemodynamic Parameters of Radial/Ulnar Artery From Baseline to 30min After Specific Nerve Block Followed by 30min After Brachial Plexus Block(Phase 1)	baseline(t0), 30 min after specific nerve block(t1), 30 min after brachial plexus block(t2)	These parameters included peak systolic velocity (PSV, cm/s), end-diastolic velocity (EDV, cm/s), time average maximum velocity (TAMAX),and was measured by Pulsed-wave Doppler(PWD) ultrasound.
Changes in Hemodynamic Parameters of Brachial Artery From Baseline to 30min After Brachial Plexus Block(Phase 2)	baseline, 30 min after brachial plexus block	These parameters included peak systolic velocity (PSV, cm/s), end-diastolic velocity (EDV, cm/s), time average maximum velocity (TAMAX), resistance index (RI), and pulsatility index (PI),The cross-sectional area of the artery imaging.Blood flow (BF) = TAMAX× CSA×60s. Relative ratio of hemodymanic parameter=30 min after brachial plexus block divide by baseline
Changes in Cross-sectional Area of Radial/Ulnar Artery From Baseline to 30min After Specific Nerve Block Followed by 30min After Brachial Plexus Block(Phase 1)	baseline(t0), 30 min after specific nerve block(t1), 30 min after brachial plexus block(t2)	The cross-sectional area(CSA, cm2) of Radial/ulnar Artery was assessed with B-mode imaging. Probe was kept perpendicular to the long axis of the artery to obtain the largest oval arterial section. The image at end diastole was chosen and measured with the cine loop.

Secondary Outcome Measures

Name	Time	Method
Changes in Skin Temperature From Baseline to 30min After Brachial Plexus Block(Phase 2)	Baseline,30 min after brachial plexus block	Skin temperature was measured at the thenar. change= 30min after brachial plexus block minus baseline
Changes in Skin Temperature From Baseline to 30 Min After Specific Nerve Block Followed by 30 Min After Brachial Plexus Block(Phase 1)	baseline, 30 min after specific nerve block, 30 min after brachial plexus block	Skin temperature(Ts) was measured at four different points within the cutaneous innervation areas of the musculocutaneous(lateral skin of forearm), ulnar(hypothenar region), radial (thumb-index web) and median(thenar) Specific points were located with skin marker to provide consistency of measurement.
Success of Brachial Plexus Block ( Phase 2)	30 min after brachial plexus block	Success of Brachial Plexus Block(BPB) was defined as the absence of sensation to in all innervation areas of above four nerves (musculocutaneous, ulnar, radial, and median nerves) 30min. after the BPB and no pain during the surgery.