Does Saline Injection Around Phrenic Nerve Reduce Incidence of Diaphragmatic Paresis Following Interscalene Block?
Condition: Phrenic Nerve Palsy
MeSH terms: Muscle Weakness; Paresis
Study type: Interventional
Phase: Phase 4

Summary: 
      Hemi-diaphragmatic palsy is a common undesirable effect of interscalene block, with an
      incidence of up to 100%. Mechanism of palsy is thought to be related to spread of local
      anaesthetic anterior to the anterior scalene muscle. We hypothesize that by injecting saline
      in this anatomical location prior to performing an interscalene block the incidence of
      phrenic palsy will be reduced.
    

Detailed description: 
      Patients will be randomised to either group S (saline group) or group C (conventional group)
      by computer generated random numbers and allocation will be enclosed in sealed envelope.
      Anaesthetist performing and/or supervising the block will be the only personnel who will be
      aware of the randomisation. Patients will be blinded to the study group. Intraoperative
      management of the case will be done by an anaesthetist blinded to the study group. Outcome
      measurements will be recorded by study observers blinded to the group allocation.

      ISB protocol Following written informed consent, the patient will have routine monitors
      attached (ECG, Pulse oximeter and non-invasive blood pressure). Intravenous access will be
      secured and patients will be placed in 45 degree head-up position for the block with head
      turned to the non-operative side. Intravenous sedation with Midazolam (2 mg) and fentanyl (50
      to 100 microgram) will be administered to all patients prior to the block. The ultrasound
      machine will be positioned on the side opposite to the block. Skin will be prepped with 2%
      Chlorhexidine (Chloraprep) following which the block will be performed under strict aseptic
      precautions with the anesthetist wearing a mask and sterile gloves. The high frequency linear
      probe (sonosite) will be aligned transversely across the neck at the interscalene level to
      identify C5 and C6 nerve roots. 2% lidocaine will be used for skin infiltration and "stop
      before block" performed prior to insertion of block needle. In plane posterior approach will
      be used with a 50 mm short bevel block needle (Braun) advanced through middle scalene muscle.
      Following this, the technique differs between the two groups.

      In group C, the needle tip will then be positioned between C5 and C6 nerve roots. At this
      location, 15 ml of 0.25% levobupivacaine will be injected in 5 ml increments with
      intermittent aspiration. The needle tip will not be repositioned unless the patient
      complaints of paraesthesia.

      In group S, at the same level chosen for interscalene block, needle tip will be positioned
      anterior to anterior scalene muscle. At this location 10 ml 0.9% saline will be injected.
      This will then be followed by repositioning of needle between roots of C5 and C6 where 15 ml
      of 0.25% levobupivacaine will be injected in 5 ml increments with intermittent aspiration.
      The needle tip will not be repositioned unless the patient complaints of paraesthesia.

      Intra-operative procedure

      Following performance of the block, all patients will receive protocolised general
      anaesthetic. Anaesthesia will be induced with 2-3 mg per kg of propofol, followed by
      rocuronium 0.6mg/kg for muscle relaxation. Anaesthesia will be maintained with inhaled
      sevoflurane (MAC 1 end tidal concentration) along with air and oxygen mixture to deliver an
      inspired oxygen concentration of 40%. Antibiotics will be given as per hospital protocol
      prior to incision. In the absence of contraindications, all patients will receive intravenous
      paracetamol 1g and parecoxib 40 mg as a part of multimodal analgesia regimen. All patients
      will also receive intravenous dexamethasone 8 mg and ondansetron 4mg for post-operative
      nausea and vomiting prophylaxis. Further doses of fentanyl in 25 microgram increments will be
      administered by the anaesthetist if the heart rate increases by more than 15% of baseline
      values obtained prior to induction. Patients will be reversed by suggamadex. If at least two
      twitches are present during TOF measurement 2 mg/kg dose will be administered. If less than 2
      twitches are present, 4 mg/kg dose will be administered.

      Post-operative procedure:

      Following transfer to recovery unit, if patient reported pain score by numerical rating score
      was >3, morphine 2 mg increments will be given intravenously by the recovery staff. This will
      be repeated every 5 minutes till the pain score is <4. In patients needing more than 10 mg of
      morphine in the recovery, anaesthetist will be requested to review the patient.
      Post-operatively, in the absence of contraindications, all patients will be prescribed
      regular paracetamol 1g, 6 hourly and celecoxib 200 mg, 12 hourly. For breakthrough pain,
      oxynorm 10 mg as needed once every 4 hours will be prescribed. Anti-emetics (ondansetron 4
      mg, 8 hourly and Cyclizine 50 mg, 8 hourly) will be prescribed for all patients to be
      administered as required. Patient will also be asked about presence or absence of subjective
      feeling of dypnoea and report satisfaction of overall anaesthetic management (numerical
      rating scale 0-10) prior to discharge from recovery.

      Diaphragm palsy and PFT assessment Diaphragm assessment and bed side spirometry will be done
      at two time points. First measurement (time point 1) will be done at the baseline as soon as
      the patient arrives in the induction room. This will be done prior to administration of any
      sedative agents or regional block. Second assessment (time point 2) will be done
      post-operatively once the patients are deemed to be ready for discharge from recovery back to
      the ward.

      For diaphragmatic paresis assessment, patients will be placed in supine position and
      curvilinear ultrasound probe (2-5 MHz) will be used. Diaphragm will be identified as
      hyperechoic line by subcostal approach using liver and spleen as acoustic windows. Patients
      will be requested to take deep breaths and M mode will be used to measure the excursion of
      diaphragm. Diaphragmatic paresis will be documented when there is more than 75% reduction in
      the excursion compared to baseline or if there was paradoxical movement of the diapragm.
      Bedside assessment will be done by radiologist blinded to the study group.

      Bedside spirometry assessments will be done with patients sitting up. They will be requested
      to make maximum inspiratory effort and blow as hard and fast in to the device. Best reading
      from three repeated measurements will be recorded.
    

Intervention name(s): Saline; Levobupivacaine
Intervention type(s): Procedure; Drug
Intervention description(s): At the location chosen for interscalene block the needle tip will be positioned anterior to the anterior scalene muscle. At this point 10ml of 0.9% saline will be injected.; the needle tip will then be positioned between C5 and C6 nerve roots. At this location, 20 ml of 0.25% levobupivacaine will be injected in 5 ml increments with intermittent aspiration. The needle tip will not be repositioned unless the patient complaints of paraesthesia
Intervention MeSH terms: Levobupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Supportive Care
Keywords: forced expiratory volume in 1 second; forced vital capacity; peak expiratory flow rate; interscalene block; diaphragmatic paresis