The Impact of Left Stellate Ganglion Block on Systemic Inflammation and Neuromodulation in CABG Surgery.

((82)) patients scheduled to undergo elective CABG by the same surgical team will be allocated randomly by computer-generated random numbers into two equal groups (n= 41).

Study groups:

Group S (Stellate Ganglion Block Group):

Patients will receive an ultrasound-guided Left stellate ganglion block prior to induction of general anesthesia. The block will be performed at the C6 level under strict aseptic precautions using 5 mL of 0.25% bupivacaine. Successful blockade will be confirmed by the appearance of ipsilateral Horner's syndrome.

Group C (Control Group):

Patients will receive standard perioperative care without stellate ganglion block and will undergo the same anesthetic and surgical management protocol as Group S.

Ultrasound guided left stellate ganglion block technique. Sedative dose of IV midazolam (1-2 mg) will be given to the patient in the preanesthetic room under supplemental oxygen nasal cannula 2-4L and electrocardiography (ECG) and pulse oximetry monitoring. Then, under local anesthesia 1% Lidocaine and complete aseptic conditions, arterial line will be inserted after ALLEN test for blood flow into the radial artery of either side for invasive blood pressure (IBP) monitoring and arterial blood gases (ABG) analysis. After that, the patient will be shifted to the operating room (OR) and Pulse oximetry, non-invasive blood pressure (NIBP), invasive blood pressure (IBP) and 5 lead electrocardiography (ECG) will be attached.

The patient will be positioned supine with the head tilted to the right and a thin cushion placed under the lt shoulder to better expose the neck. The skin will be disinfected, and patients will be instructed to avoid speaking, swallowing or making other movements during the procedure, raising their hands if they experience discomfort.

A trained anesthesiologist will use the SonoSite S series ultrasound machine (FUJIFILM SonoSite, Bothell, Washington, USA) to position the HFL38x/13-6 MHz high-frequency linear array probe horizontally at the C6 level. The internal jugular vein, common carotid artery and long neck muscle will be identified through transverse scanning. For patients in the SGB group, a 25-gauge needle will be inserted laterally at the level at C6, with the needle tip reaching the fascia plane of the sympathetic nerve chain, deep to the posterior fascia layer of the carotid sheath and superficial to the fascia covering the long neck muscle. After confirming negative pressure aspiration with no blood return, 5 mL of 0.25% bupivacaine will be injected into the SG. The anesthesiologist will assess the success of the SGB based on the presence of Horner's syndrome, characterized by miosis, ptosis, enophthalmos, nasal congestion, conjunctival congestion, facial redness, absence of sweating and a warm sensation. Control group patients will not receive any block even SHAM block.

General anesthesia technique and intraoperative management. Anesthesia will be induced with fentanyl (1-2 mcg /kg), Propofol (.5-1.5mg/kg) injected slowly and after ensuring adequate depth of anesthesia, rocuronium (0.9 mg/kg) will be given to facilitate endotracheal intubation with a cuffed appropriate size endotracheal tube and after ensuring the correct position and adequacy of ventilation are confirmed with capnography and lung auscultation, the tube is fixed, and the patient is ventilated (Datex-Ohmeda 7100 anesthesia machine) with 6 to 8 ml /kg predicted body weight using volume-controlled mode of ventilation. Respiratory rate is set initially to 12 breaths/ min and adjusted subsequently according to arterial blood gas (ABG) analysis to maintain normocarbia using. Central Venous Catheter, urinary catheter, and nasopharyngeal temperature probe will be inserted under completely aseptic technique. Anesthesia will be maintained with sevoflurane carried by oxygen/air mixture (the ratio is adjusted to maintain SpO2 between 94 % to 98 %), fentanyl (1:5 mic /kg/hr.) and rocuronium (0.3 mg/kg/h). Additional increments of fentanyl (2 mcg/kg) will be administered if mean arterial blood pressure (MAP) or heart rate (HR) rise in response to stressful surgical stimuli greater than 20% above baseline. The following parameters will be continuously monitored during the procedure: Heart rate and rhythm, O2 saturation by pulse oximetry (SpO2), end-tidal CO2, Invasive arterial blood pressure, central venous pressure using (CVP), Core body temperature using esophageal probe, urine output, and neuromuscular blockade using peripheral nerve stimulation.

Cardiopulmonary Bypass

• Standardized CPB protocol for all patients:
• Membrane oxygenator, arterial line filter.
• Priming: saline 1000-1500 mL with 5000 IU heparin.
• Anticoagulation: Heparin 300-400 IU/kg to maintain ACT >480 seconds.
• Flow rate: 2.2-2.4 L/min/m².
• Temperature: Moderate hypothermia (32-34°C) or normothermia (36-37°C) per surgeon preference (will be recorded and analyzed).
• Myocardial protection: Antegrade cold blood cardioplegia or Custodial® per institutional standard.

During CPB:

• Propofol infusion continued as needed for sedation.
• Neuromuscular blockade maintained.

Inclusion criteria

• All elderly (≥65 years) patients of both genders, as according to the World Health Organization, the chronologic age of 65 years was accepted by most developed countries in the world as a definition of "elderly" or older person. Patients scheduled for elective cardiac surgery under general anesthesia.14
• American Society of Anesthesiologists (ASA) physical status class II or III.
• Patients will be stratified according to their baseline surgical risk utilizing the EuroSCORE II tool >4%15.
• American Society of Anesthesiologists (ASA) physical status class II or III.

Exclusion criteria

• Pre-existing dementia or significant cognitive impairment.
• History of stroke or cerebrovascular disease.
• Contraindications to SGB (e.g., coagulopathy, local infection, or anatomical abnormalities).
• Preoperative use of antipsychotics or antidepressants.
• Sinus bradycardia <50bpm &complete heart block
• BMI>35
• Redo or emergency surgery.
• On preoperative mechanical ventilation and long sedation time.
• Low EF patients <35%.