Effectiveness of Low Volume Versus High Volume of Local Anesthetic in Ultrasound Guided Combined Supraclavicular and Interscalene Block for Upper Limb Surgery

Effectiveness of Low Volume Versus High Volume of Local Anesthetic in Ultrasound Guided Combined Supraclavicular and Interscalene Block for Upper Limb Surgery; A Randomized Controlled Double Blinded Study.

The aim of this study is to evaluate the effectiveness of low versus high volumes of local anesthetic in ultrasound-guided combined supraclavicular block (SCB) and interscalene block (ISB) for upper limb surgery. This randomized, controlled trial will assess the analgesic effectiveness of low-volume local anesthetic in these blocks.

We hypothesize that a low volume will provide similar analgesic effects to a high volume, with fewer complications. The study will involve 40 adult ASA I and ASA II patients undergoing upper limb surgery, divided into two groups: Group A (low volume) and Group B (high volume).

The primary outcome will compare intraoperative and postoperative analgesic effects of different volumes.

The secondary outcome will evaluate complications related to local anesthetics (toxicity) and injection techniques (e.g., phrenic nerve palsy, pneumothorax, hematoma).

I. Study setting and location:

The study will be conducted in Souad Kafafi Universty Hospital - Misr University for Science and Technology ( MUST).

II. Study population:

Study will be conducted on (40) adult ASA І & ASA ІІ patients who will undergo Upper limb surgery in Souad Kafafi Universty Hospital - MUST University. Patients will be divided into two equal groups; Group A; Low volume of local anesthetic and Group B; High volume of local anesthetic in Ultrasound guided combined supraclavicular and interscalene block.

III. Eligibility Criteria:

1. Inclusion criteria:

   The study will recruit 40 ASA physical status I, II patients of both sexes, 18 - 65 years old presented for Upper limb surgery.

2. Exclusion criteria:

1. Refusal of patients to participate. 2. History of allergic reactions to local anesthetics. 3. Bleeding disorders with INR > 1.5 and/or platelets < 50 000. 4. Rash or signs of infection at the injection site. 5. Emergency procedure. 6. ASA ІІІ to VI patients.

IV. Study Procedures

1. Randomization An online randomization program will be used to generate random list and to allocate patients into two study groups: Low volume Local anesthetic group A (n=20) and High volume Local anesthetic group B (n=20) in Ultrasound guided combined supraclavicular and interscalene block for Upper limb surgery . Random allocation numbers will be concealed in opaque closed envelops. The patient and investigator performing the block and assessing study outcomes will all be blinded to the study group allocation.
2. Study Protocol:

Following approval from research and ethical committee of Faculty of Medicine, MUST University, The study will recruit forty ASA physical status I, II patients of both sexes, 18 - 65 years old, who will undergo upper limb surgery. A written informed consent from patients will be provided preoperatively.

Exclusion criteria of this study will be; refusal of the patient, trauma survey on head neck, chest and abdomen should be free, patient with neurological deficits involving upper limb, bleeding tendency, anticoagulation therapy, patients with allergy to local anesthetics, local infection at the injection site, patients on sedative or antipsychotic drugs and body mass index (BMI) > 35.

Group A: 20 patients, will receive ultrasound guided combined Supraclavicular Block (SCB) with 7-10 ml and Interscalene Block (ISB) with 7-10 ml.

Group B: 20 patients, will receive ultrasound guided combined Supraclavicular Block (SCB) with 15-20 ml and Interscalene Block (ISB) with 15-20 ml.

The primary outcome of this study will be to compare the analgesic effects (intraoperative and postoperative) of different volumes of local anesthetic in Ultrasound guided combined SCB with ISB for upper limb surgery.

The secondary outcome will be to assess complications of local anesthetic and techniques of injection All patients will be subjected to systematic preoperative assessment including history, examination, and investigations. Visual analogue scale score (VAS) (0-10) will be explained to all candidates where zero corresponds to no pain and 10 is indicative of the worst unbearable pain.

Patient positioning and preparation for the block:

On arrival to the preparation room: A peripheral IV cannula (18 G) will be inserted in the contralateral upper limb (non-operable limb); premedication using 2 mg midazolam IV.

Patients will be transferred to the operating room where basic monitoring (Electrocardiography (ECG), Non- invasive Blood Pressure (NIBP) and pulse oximetry (SpO2) will be attached. Baseline heart rate, blood pressure, oxygen saturation and respiratory rate will be recorded as pre-block values.

The patient will be placed in supine position with the head turned 45 degrees to the contralateral side. For the ultrasound-guided supraclavicular block, an ultrasound machine (Mindray China DC-N2-Diagnostic Ultrasound System) and a 10-14 MHz linear type probe will be used. After skin preparation and local anesthetic infiltration of skin, the supraclavicular fossa will be scanned to locate the subclavian artery, first rib, pleura and brachial plexus, then a 22 gauge, 9 cm, echogenic needle (B. Braun) will be advanced from lateral to medial in plane with the probe. The needle will be advanced towards the upper trunk and the "corner pocket" where the lower trunk commonly lies and the local anesthetics will be injected.

For ultrasound-guided Interscalene block, the ultrasound transducer will be placed in the axial, oblique plane at the level of the cricoid cartilage to obtain the transverse view of the brachial plexus. Nerves in the Interscalene groove appear hypoechoic, distinctly round or oval, and will be located between the anterior and middle scalene muscles. 9 cm 22 G needle will be inserted at the outer end of the ultrasound transducer after local anesthetic infiltration of the skin. The needle will be advanced in plane with the transducer; then injection will be done toward C5, C6 and C7 cervical nerve roots.

After injection of local anesthetic the patients will be observed for the onset of both sensory and motor blockade and duration of analgesia (first request of analgesic) in both groups.

Postoperative assessment and analgesic regimen:

VAS score of pain will be assessed immediately postoperative in the PACU and every 6 hours for 24 hours.

The time to the first request of rescue postoperative analgesic will be "the time interval between the onset of block and the first request to postoperative analgesia". When patients first complain of pain "1st analgesia request".

In the postoperative period if patients start to complain (VAS >3); rescue analgesia will be given in the form of pethidine 0.5-1 mg/kg/6hours, paracetamol (Perfalgan®) 1gm IV drip/6 hours and ketorolac 30mg IV/8 hours, till VAS score become ≤ 3.

V. Study outcomes

1. Primary outcome Post-operative pain score by VAS scale.

2. Secondary outcome(s)

   • Time to first request of postoperative rescue analgesics.
   • Perioperative hemodynamic parameters.
   • Incidence of perioperative complications.

Sample size Sample sizing will be based on results obtained from previous studies. Calculation of the sample size revealed that at least 18 patients in each group were needed to detect a difference in pain score and to detect the importance of Analgesia in reduction of pain in compliance as small as 1.5 times its standard deviation (SD) with a power of 0.9 and a significance level of 0.05. The sample size was increased by two patients in each group (20 patients in each group) to compensate for misinterpretations of pain score in each group.

Statistical analysis The Statistical Package of Social Science software program (SPSS), version 21 (Chicago, IL, USA) will be used for all statistical comparisons. Continuous quantitative normally distributed data will be expressed as means and standard deviations (SD), while non-normally distributed data will be expressed as median and range. Qualitative nominal data will be expressed by percentage.

After testing for normality, continuous variables will be compared using t-test or Mann-Whitney U test as appropriate. Categorical variables will be compared using Chi- squared test or Fisher's exact test as appropriate. correction. A pvalue <0.05 will be considered statistically significant

Inclusion Criteria:

• Patients aged 18 to 65 of both sexes
• ASA classification I or II
• Scheduled for upper limp surgery
• Will be randomized 1:1 into two groups; group A; low volume local anesthetics (15-20ml) and group B; high volume local anesthetics (30-40 ml).

Exclusion Criteria:

• Patients who refuse participation.
• Have allergies to local anesthetics.
• Phrenic nerve dysfunction.
• Chronic opioid use.
• ASA III or higher classification.
• Coagulopathy (bleeding disorders with INR > 1.5 and/or platelets < 50 000)
• Severe chronic obstructive pulmonary disease.
• Local infection at the injection site