The Prevention of Hypotension After Epidural Analgesia After Major Surgery

The Prevention of Hypotension After Epidural Analgesia After Major Surgery by Adding Epinephrine to Infusions to Counteract Sympathectomy: a Double- Blind, Controlled, Randomized, Prospective Dose-finding Study

Epidural analgesia via continuous epidurally infused local anesthetic agent (LA) is widely and very successfully used routinely for perioperative pain control in patients undergoing major orthopedic and abdominal surgery since 1928. The choice currently depends on the preference of the APS physician in charge of the case. A frequent unwanted side effect of epidural block is hypotension due to the epidurally injected LA blocking the sympathetic nerves and thus the patient's response to hypotension, which is usually due to hypovolemia and/or an unopposed parasympathetic (via the vagus nerve) nervous system. The purpose of this research study is to see if adding epinephrine, to the epidural anesthetic will decrease possible side effects, such as low blood pressure, and lead to a better effect of the epidural anesthetic.

Participants undergoing epidural analgesia to treat perioperative pain associated with major surgery will be approached for their willingness to participate in the study. Participants undergoing major thoracic, abdominal, or orthopaedic surgery for whom thoracic or lumbar epidural block would be indicated and planned for intraoperative and postoperative analgesia as per the University of Florida Acute Pain Service (APS) usual and routine practice will be included in this study. All participants will receive a standardized continuous epidural block at the appropriate level for the planned surgery by the APS physicians in the block room that day. For the standardized continuous epidural block, placement will be confirmed with loss of resistance technique (LORA), wave form analysis or nerve stimulation. Participants will be randomly allocated by computer-generated randomization to one of four groups. This will be a quintuple blinded prospective study. The anesthesiologist managing the intraoperative anesthesia, the anesthesiologists (APS) placing the blocks and following the participants on the floors, the research nurse taking the measurement, the surgeons, nor the participants will be aware of what combination of drugs are used for the epidural block infusion. The three groups will consist of: Group A (Ropivacaine 0.2% infusion; Control group) Group B (Ropivacaine 0.2% + 2 mcg/mL epinephrine) Group C (Ropivacaine 0.2% + 5 mcg/mL epinephrine)

The participants in this group will receive standard anesthesia, epidural analgesia with 0.2% ropivacaine with no epinephrine added during the procedure.

The participants in this group will receive standard anesthesia (Ropivacaine 0.2%) with the addition of 2mcg/mL of epinephrine during the procedure.

The participants in this group will receive standard anesthesia (Ropivacaine 0.2%) with the addition of 5mcg/mL of epinephrine during the procedure.

Epidural block infusion with Ropivacaine 0.2% will be provided as the anesthesia per standard of care during the procedure.

Participants will receive epinephrine in their epidural block infusion during the procedure. The amount of epinephrine provided during the procedure will be based on the group assignment.

Hypotension will be assessed by systolic blood pressure (SBP) > 20% below the baseline preoperative measurements and acquired before the epidural or any sedation has been administered and the intra-operative period

Spread of local anesthetic (block) effect as tested by sensitivity to cold recorded every hour postoperatively and every 8 hours for the subsequent 72 hours after discharge from the PACU.

Ambulation on post-op day 1, post-op day 2 and post-op day 3, will be recorded by distance ambulated per 24-hour period.

Opioid usage data will be recorded and converted to morphine equivalents and averaged for day 0, and post-op days 1, 2, and 3 per group.

Side effects such as pruritus, nausea/vomiting, and respiratory depression (defined as respiratory rate less than 10 breaths per minute of oxygen saturation more than 7 points lower that the patients preoperative value on room air) will be recorded.

Inclusion Criteria: undergoing epidural analgesia to treat perioperative pain associated with major surgery undergoing major thoracic surgery undergoing major abdominal surgery undergoing major orthopaedic surgery Exclusion Criteria: sepsis acute trauma coagulopathy preoperative hemodynamic instability symptomatic coronary artery disease patients from the ICU whose tracheas were intubated for any cause allergies to medications in the protocol primary or secondary block failure