Intravenous(IV) vs. Erector Spinae Plane Blocks in Cardiac Surgery

Interfascial plane blocks have been developed for analgesia, among which the erector spinae plane (ESP) has gained popularity. The ESP block has been hypothesized to provide truncal analgesia by spread of local anesthetic into the paravertebral space. Recent studies have contested this idea showing unreliability in the spread of the local anesthetic into the paravertebral space.

Post-operative pain is a significant issue following open heart surgeries and poorly controlled pain can result in significant cardiorespiratory morbidity. Many patients suffer pain both at rest (49%) and on movement (62%) following open heart surgeries via sternotomy and adequate pain management requires closer re-assessment and treatment. The intensity of pain is noted to be higher in the first 48 hours post surgery and hence modalities to control pain may make the greatest difference in the first 2 days after surgery. Enhanced recovery pathways utilizing multimodal analgesia have shown significant analgesic and opioid sparing benefit while minimizing ICU and length of hospital stays. Some multimodal regimens have also incorporated regional blocks but the optimal analgesic regimen remains elusive. The ESP block has been hypothesized to provide truncal anesthesia by spread of local anesthetic into the paravertebral space, but recent studies contest this idea. Bilateral paravertebral blocks can result in higher than acceptable levels of local anesthetic in both cardiac and non-cardiac surgical patients and this may be true following bilateral erector spinae plane (ESP) as well. Hence, the pharmacokinetic profile of administered local anesthetics is necessary given the lack of information about the local anesthetic systemic levels following bilateral ESP.

Bilateral ultrasound guided erector spinae plane catheter placement for the administration of lidocaine. Dose will be 2 mg/kg ideal body weight. Bolus will be divided equally between the two ESP catheters. This is followed by lidocaine infusion via ESP catheter at 2 mg/kg/hr for 48 hours after catheter placement.

Sham block procedure (catheter will be taped to subjects skin). Subject will receive a bolus of lidocaine at 2 mg/kg ideal body weight. This is followed by lidocaine infusion via intravenous route at 2 mg/kg/hr for 48 hours after sham catheter placement.

Lidocaine will be administered via intravenously. Initial dose will be at 2 mg/kg ideal body weight followed by dosing at 2 mg/kg/hr for 48 hours

Lidocaine will be administered via ESP catheter. Initial dose will be at 2 mg/kg ideal body weight split between two catheters followed by dosing at 2 mg/kg/hr for 48 hours

Pain scores will be recorded at baseline and at two hour intervals. The patients are asked to report their pain on a scale of 0 to 10 with 0 being no pain and 10 is the most imaginable. The variables will be presented as mean and standard deviation.

To assess if either route (IV or ESP catheter) of lidocaine provided maximal pain relief when compared to its counterpart, the type and amount of medication provided the subject will be recorded. The amounts of opioid medications required to provide relief during the first 48 hours will be tabulated in morphine equivalents. A comparison will be made between the two route to see if one route is optimal over the other. The variables will be presented as mean and standard deviation.

Inclusion Criteria: Undergoing elective cardiac surgery for coronary artery bypass graft (CABG) or valve surgery via sternotomy. English speaking Exclusion Criteria: Emergency surgery Allergy to medications (ie lidocaine) BMI less than 20 or greater than 35 Major liver or kidney dysfunction or other pre-existing major organ dysfunction Revision cardiac surgery Surgery via thoracotomy Off-pump coronary artery bypass Narcotic dependent (Opioid intake morphine equivalents greater than 10mg/day for more than 3 months Chronic pain (ie fibromyalgia) Significant central nervous system or respiratory disease Hematological disorders or de-ranged coagulation parameters Psychiatric illness that impedes subject from providing informed consent Pre-operative neurological deficits Language barrier Inability to provide informed consent Prisoner status Pregnancy