PVB Versus TAP in Hepatic Patients Undergoing Laparoscopic Cholecystectomy
Condition: Ultrasound Therapy; Hepatic Impairment; Laparoscopic Cholecystectomy
Study type: Interventional

Summary: 
      The Era of using ultrasound guided blocks provides an attractive and more or less safe
      alternative to other techniques. Among these blocks is ultrasound-guided transverse abdominis
      plane block (USG-TAP block) that controls pain by local anesthetic injection into the
      neurofascial plane of the abdominal muscles. Ultrasound-guided thoracic paravertebral block
      (USG-TPVB) is another technique in which local anesthetic is injected nearby the thoracic
      vertebra where spinal nerve emerges from the intervertebral foramina. It provides ipsilateral
      somatic and sympathetic blockade in many dermatomes around the injection site. The aim of
      this study is to verify which technique is more efficient in reducing the intra- and
      postoperative analgesic requirements in hepatic patients.
    

Detailed description: 
      Study design:

      Prospective randomized clinical study, sixty patients will be randomly allocated to one of
      two groups according to a computer-generated random number table of 30 patients each to
      receive ultrasound-guided either TAP block (Group T) or PVB (Group P).

      Study setting and location Theodor Bilharz research institute.

      Study population:

      60 patients (ASA II or III ) undergoing laparoscopic cholecystectomy under general anesthesia
      will be recruited and will be randomly allocated using a computer-generated random number
      table of 30 patients each to receive either:

        1. Paravertebral block group or

        2. Transverse abdominis muscle block group.

      Study Procedures

      Methodology in details :

      Anesthesia technique:

      Preoperative :

        -  During the pre-operative period visual analog scale (VAS) for pain assessment from 0 to
           10, with 0 meaning no pain and 10 meaning the worst pain imaginable will be explained to
           patients.

        -  Midazolam 0.05 mg/kg will be given as pre-medication upon arrival to the operating room
           then 500 ml lactated Ringer's solution will be administered slowly iv as a pre-load

      Monitoring :

      ECG, pulse oximetry, noninvasive blood pressure, gas analyzer, bispectral index (BIS), and
      TOF-Guard module for neuromuscular monitoring (Dragger Infinity Kappa version VF-5W, Germany)
      are connected to the participants.

      Induction and maintenance

        -  During mask pre-oxygenation, patients' baseline hemo-dynamic parameters will be recorded
           regarding blood pressure and heart rate.

        -  General anesthesia will be standardized for all patients with :

      1.5- 2 µg / kg fentanyl, 2-2.5 mg/kg 2% propofol then 0.5 mg/kg atracuriam will be
      administered for muscle relaxation.

        -  Patients will be intubated and lungs mechanically ventilated to maintain end-tidal CO2
           between 30 to 35 mmHg. Fresh gas flow oxygen in air 30-40% at a rate of 3 L/min for 10
           minutes will be administered then decreased to 1L/min using a closed system (Fabius GS,
           Dräger, Lübeck, Germany).

        -  The patients will receive 1 MAC desflurane which is defined as an expired fraction of
           6.0 vol. %. Then the dial-up percentage will be adjusted to establish a BIS value
           between 40- 50.

        -  Top- up doses of 0.15 mg/kg atracurium will be given to maintain intra-operative muscle
           relaxation according to TOF-guard.

        -  All surgical procedures will be done in the range between 10 am and 2 pm and by the same
           surgical team.

        -  Patients will be randomly allocated to one of the 2 groups :

      I. In group P, USG-TPVB will be performed with the patient is in sitting position, a linear
      transducer (6-15 MHz) placed just lateral to the spinous process, the depth of field will be
      set about 3 cm to start scanning. The transverse processes and ribs will be visualized as
      hyper echoic structures with acoustic shadowing below them. Once the transverse processes and
      ribs are identified, the transducer is moved slightly cauded into the intercostal space
      between adjacent ribs to identify the thoracic para-vertebral space (PVS) and the adjoining
      intercostal space. The PVS appears as a wedge-shaped hypo echoic layer demarcated by the
      hyper echoic reflections of the pleura below and the internal intercostal membrane above. It
      is important to visualize the pleura very clearly at all times. The hyper echoic line of the
      pleura and underlying hyper echoic air artifacts move with respiration. The needle stimuplex
      needle (BRAUN Stimuplec D Plus 0,71*50- 80 mm 22 G* 2'', 15°) will be inserted and 0.5 - 1 ml
      local anesthetic injection administered to show the displacement of pleura downward followed
      by 15 cc bupivacaine 0.25% Marcaine® flacon, Astra Zeneca, Sweden) into each side the PVS.
      Visualization of the needle and its tip and controlling its path at all times are essential
      to avoid inadvertent pleural puncture or entry into the intervertebral foramen. A pop often
      is felt as the needle penetrates the internal intercostal membrane. Intra-vascular injection
      will be eliminated by negative aspiration before injection. Local anesthetic (15- 20 ml) is
      slowly injected in small increments, avoiding forceful high-pressure injection to reduce the
      risk of bilateral epidural spread.

      II. In group T, USG-TAP Subcostal blockage will be done in plane technique with 22 G needle
      (BRAUN Stimuplex D Plus 0,71 50- 80 mm 22 G). The puncture area and the ultrasound probe will
      be prepared in an aseptic manner. The ultrasound probe is placed in a transverse plane to the
      lateral abdominal wall in the midaxillary line, between the lower costal margin and iliac
      crest. On each side, The rectus abdominis and underlying transverses abdominis muscles near
      the costal margin and xiphoid process will be identified. In-plane image will be obtained and
      the needle will be inserted through the rectus muscle 2-3 cm medial to the probe. Once the
      tip of the needle is visualized to be in the plane, 0.25% bupivacaine will be administered
      incrementally. The drug will be injected along the oblique subcostal line, extending
      inferolaterally from the xiphoid towards the anterior part of the iliac crest by multiple
      punctures; a total of 15 ml will be given on each side.

        -  When heart rate and blood pressure exceeds 20% of baseline in spite of adequate level of
           anesthesia guided by BIS, boluses of 0.5 µg/kg fentanyl will be given & the total
           fentanyl dose will be recorded.

        -  Atropine 0.5 mg increments will be used to control bradycardia (<50 beat min-1) while
           hypotension (less than 20% of preanesthetic level) will be managed by increasing fluid
           infusion rate, decreasing inhalational anesthetic concentration and ephedrine 5 mg.

        -  Reversal of neuromuscular blockade will be achieved by IV administration of neostigmine
           0.05 mg kg-1 and atropine 0.02 mg kg-1.

        -  Patients will be extubated and transferred to post- anesthetic care unit.

      Collected parameters:

      Before the operation:

        -  Age, weight, height, sex, ASA, medical history as well as physical examination will be
           documented.

        -  Viral hepatitis markers and liver ultrasonography will be done to verify liver
           affection.

        -  The Child-Turcotte-Pugh (CTP) classification including preoperative serum albumin, serum
           bilirubin, ascites, prothrombin time (PT), or INR (modified CTP score), and grade of
           encephalopathy will be reported.

        -  Liver functions AST, ALT and ALP will be taken preoperatively, immediately
           postoperatively and 24 hours later to rule out any change in liver functions.

        -  Regarding hemodynamic parameters blood pressure and heart rate will be monitored in each
           group prior and following the block, induction of general anesthesia as well as
           endotracheal intubation, then every 10 min till end of the operation.

        -  The total amount of fentanyl consumption throughout operation will be taken.

        -  Total anesthetic consumption will also be calculated according to the following formula
           (18):

      Total liquid (ml) = from t=0 to t=end dt The time from the start of end-tidal control (t=0)
      until the time when the vaporizer will be switched off at the end (t=end).

      A conversion factor is detected from the amount of vapor given from each ml of volatile
      liquid: conversion factor of desflurane is 209 ml calculated from the following formula:

      Conversion factor = [density of volatile liquid (g/ml) ×volume at room temperature and
      pressure (24000 ml)] /molecular weight (g).

      Total volatile values used will be calculated by summing the product of usage rate by the
      duration of each time epoch.

      Average volatile usage (ml/h) =

      Postoperatively:

        -  Pain intensity will be estimated by a numeric rating scale (NRS) (0 = no pain, 10 =
           worst imaginable pain) at rest and on coughing at 2, 4, 6 and 24 hours following the end
           of surgery. When VAS is exceeding four, boluses of 5 mg intravenous pethidine were given
           till VAS declined to be less than 4.

        -  Time to first analgesic demand as well as total analgesic requirements will be recorded.

        -  Any complications regarding the procedure or the block will be noted as intraperitoneal
           injection, bowel hematoma and transient nerve palsy as well as Local anesthetic
           toxicity.

        -  Length of hospital stay.

        -  Total amount of analgesia (paracetamol).
    

Intervention name(s): ultrasound-guided nerve block PVB; ultrasound-guided nerve block TAB
Intervention type(s): Other; Other
Intervention description(s): Thoracic paravertebral block guided by ultrasound device which allows visualizing the surrounding anatomy and placement of the needle at the target location in real time.; Transverse abdominis plane block guided by ultrasound device which allows visualizing the surrounding anatomy and placement of the needle at the target location in real time.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Health Services Research
Keywords: Ultrasound- guided; PVB; TAP; Hepatic; Laparoscopic Cholecystectomy