Different Local Anesthetic Volumes in Brachial Plexus Block
Condition: Diaphragmatic Disorder
Study type: Interventional

Summary: 
      This prospective randomized study will be carried out on 75 patients in our university
      hospitals presented for shoulder arthroscopy under general anesthesia and ultrasound-guided
      interscalene brachial plexus block.

      All the patients will receive ultrasound-guided interscalene brachial plexus block with
      injection of local anesthetic volume according to the group of the patient

        -  Group I (25 patients): patients will receive 5 ml levobupivacaine 0.25% ISPB

        -  Group II (25 patients): patients will receive 10 ml levobupivacaine 0.25% ISPB

        -  Group III (25 patients): patients will receive 15 ml levobupivacaine 0.25% ISPB After
           ensuring adequate sensory and motor blockade, general anesthesia will be carried out.

      The primary outcome measurement will be the incidence of diaphragmatic hemiparesis 30 minutes
      after performing the block detected by US assessment of diaphragmatic excursion and the
      secondary outcome will be the postoperative pain scores and opioid consumption.
    

Detailed description: 
      This prospective randomized double-blind study will be carried out on 75 patients who will be
      presented for shoulder arthroscopy in Tanta university hospitals over 9 months duration
      (September 2020- May 2021) which will be started immediately after obtaining the approval
      from the institutional Ethical Committee.

      Informed written consent will be obtained from all the participants, all patients data will
      be confidential and will be used for the current study only.

      Patients will be randomly classified using a computer-generated software of randomization
      into 3 groups:

        -  Group I (25 patients): patients will receive 5 ml levobupivacaine 0.25% ISPB

        -  Group II (25 patients): patients will receive 10 ml levobupivacaine 0.25% ISPB

        -  Group III (25 patients): patients will receive 15 ml levobupivacaine 0.25% ISPB

      Anesthetic technique The patients will be assessed preoperatively in the anesthesia clinic
      through history taking, examination, and appropriate investigation. Pulmonary function tests
      (PEFR, FEV1, FVC, and FEV1/FVC) will be performed preoperatively. On arrival of patients to
      the preparation room, an intravenous line will be established and a fluid preload will be
      started (7 ml/kg of lactated ringer solution) and the patient will be connected to monitor
      that consist of 5 leads ECG, non-invasive blood pressure, pulse oximeter, and temperature
      were applied.

      The patients will lie supine with ultrasound assessment of the diaphragmatic excursion during
      quiet breathing, (excluding deep breathing, crying, participants with nasal obstruction,
      rhinorrhea, or cough, and participants with abdominal pain). Then midazolam 2 mg will be
      injected slow i.v with the application of nasal cannula (2-3 L/min) to the patient. Then,
      ultrasound-guided interscalene brachial plexus block will be done under aseptic precaution
      with an injection of the pre-prepared local anesthetic mixture with its volume according to
      the group of the patient.

      The patients will be monitored for 30 minutes before induction of anesthesia, during which
      assessment of the sensory blockade will be carried out. The sensory block will be assessed by
      exposure to cold (ice piece) to the area of the shoulder and the upper arm. The motor block
      will be evaluated by determining patients ability to abduct the shoulder and flex the elbow
      against gravity (0 = no block Y full strength, 1 = partial block Y weak but able to abduct or
      flex against gravity, 2 = complete block Y no activity of muscle group). Preserved sensation
      to the cold or strength to abduct the shoulder after 30 minutes from performing the block at
      the area of the shoulder and upper arm will be considered as failed block and the patient
      will be excluded from the study. Ultrasound assessment of the diaphragmatic excursion during
      quiet breathing will be done again 30 minutes after performing the block.

      Induction of anesthesia will be carried out after 3 minutes of pre-oxygenation through a
      well-fitted face mask using 80% oxygen by fentanyl 1 ug/kg, propofol 1.5 mg/kg, and
      atracurium 0.5 mg/kg to facilitate tracheal intubation. After securing the airway through a
      suitable sized endotracheal tube, the patient will be connected to a mechanical ventilator
      with its parameters adjusted to maintain the end-tidal carbon dioxide 34-38 mmHg. Maintenance
      of the anesthesia will be performed by isoflurane 1.2 % in a low flow gas mixture (1 L/min)
      composed of oxygen: air 1:1 and incremental doses of atracurium 0.1 mg/kg. A temperature
      probe will be inserted in the nasopharynx for core temperature monitoring. The depth of
      anesthesia will be monitored by the bispectral index (Covidien, Mansfield, MA, USA). The BIS
      values will be kept 40-60. An additional bolus dose of fentanyl 0.5 ug/kg was used in case of
      increase BIS more than 60 or increase in the heart rate or mean arterial pressure by more
      than 15 % of the baseline values.

      At the end of the surgery, the isoflurane will be switched off with reversal of muscle
      relaxation by neostigmine 0.05 mg/kg and atropine 0.01 mg/kg with awake tracheal extubation
      and transfer of the patient to the recovery room for postoperative monitoring and
      supplementation of oxygen through nasal cannula (2-3 L/min). All the patients will receive 4
      mg dexamethasone i.v after induction of anesthesia and 4 mg of ondansetron i.v at the end of
      the surgery to guard against postoperative nausea and vomiting. Also, paracetamol 1 gm i.v
      infusion every 6 hours will be given routinely to all patients in the postoperative period.
      In the PACU, ultrasound-guided assessment of the diaphragmatic excursion will be done. Also,
      pulmonary function (PEFR, FEV1, FVC, and FEV1/FVC) tests will be repeated before discharging
      the patients from the recovery room after exclusion of the effect of sedation by the aid of
      the modified observer¡¦s assessment of alertness.

      Bradycardia (heart rate less than 50 b/min) will be managed by atropine 0.3 mg i.v) and
      hypotension (mean arterial pressure less than 65 mmHg or decrease by more than 20 % of the
      pre-anesthesia value) will be managed by ephedrine 10 mg i.v and i.v infusion of ringer
      lactate that may be repeated.
    

Intervention name(s): Low volume interscalene brachial plexus block; Intermediate volume interscalene brachial plexus block; High volume interscalene brachial plexus block
Intervention type(s): Procedure; Procedure; Procedure
Intervention description(s): ultrasound-guided interscalene brachial plexus block with 5 ml levobupivacaine 0.25%; ultrasound-guided interscalene brachial plexus block with 10 ml levobupivacaine 0.25%; ultrasound-guided interscalene brachial plexus block with 15 ml levobupivacaine 0.25%
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Supportive Care
Keywords: Excursion; Diaphragm; Shoulder arthroscope; Postoperative analgesia