Ideal Initial Bolus and Infusion Rate for Erector Spinae Plane Block Catheters

This study would like to identify the best starting dose and infusion rate for nerve blocks and nerve catheters related to the erector spinae plane block that can improve functional status and pain control on cardiac surgery patients and minimize the necessity for opioid pain control using a continuous reassessment model.

The study will continue taking steps in helping to identify the role erector spinae plane nerve blocks have in thoracic surgery. This is a relatively new nerve block (first identified and described in 2016) and the studies that have been done and the case series that have been reported have been very promising in supporting its role in thoracic surgery. As it is a plane block (not around a specific nerve but in a general area), larger volumes and doses often have to be used in these sorts of blocks (such as a transverses abdominalis plane block) to get good spread of the local anesthetic in the plane to reach the desired nerves that pass through this plane with one injection. Our hospital has been doing these blocks for patients as a standard of care for them, but this study will take a closer look to see if there is an optimal dose and volume of medicine to improve patients' functional status and pain control to minimize the need for opioids. The study will use a continuous reassessment model to determine the optimal dose.

patients receiving bilateral catheters (such as for patients undergoing sternotomies/midline incisions or with planned bilateral thoracotomy incisions)

patients who only have one catheter in place (such as in patients who have unilateral thoracotomies and not midline sternotomies)

Variable initial post-operative dose of 10cc to 40cc bilaterally with a variable programmed dose to be repeated afterward of 10cc to 40cc of 0.2% ropivacaine every 6 hours bilaterally.

Variable initial post-operative dose of 10cc to 40cc unilaterally with a variable programmed dose to be repeated afterward of 10cc to 40cc of 0.2% ropivacaine every 6 hours unilaterally.

Dose at which 50% of patients achieve a clinically significant nerve block after a single bolus and after periodic programmed boluses of Ropivacaine as represented by either an adequate decrease in sensation of the chest (covering at least 5 dermatomes) or an improvement in vital capacity breaths (of 500 mL or more)

Monitoring for changes in electrical conduction in the heart as monitored by the continuous 5 lead electrocardiogram tracing, watching for any side effects.

The area of numbness experienced in the chest wall as measured using a pinprick test and documented on a cartoon map showing a chest wall and dermatomal borders

Inclusion Criteria: patients undergoing planned thoracotomies and sternotomies for cardiothoracic surgery who will be taken to the cardiac surgery ICU postoperatively Exclusion Criteria: BMI >40 infection at the proposed catheter site ongoing sepsis/bacteremia patient unable to sit up for the procedure patients requiring significant vasopressor support (>1 vasopressor) patient refusal less than 18 years of age (they are managed in the pediatric ICU rather than the Cardiac Surgery ICU)