Bupivacaine

* BACKGROUND Postoperative pain plays a significant part in the recovery of patients after open heart surgery.

* OBJECTIVE To determine if the use of intercostal bupivacaine with epinephrine is associated with decreases in use of narcotics and intubation times after open heart surgery.

* METHODS A randomly selected experimental group of 25 patients received injections of bupivacaine with epinephrine in the intercostal tissues before chest closure in open heart surgery. A control group of 22 patients received no bupivacaine, only standard care. Postoperative use of narcotics and intubation times were determined for both groups.

* RESULTS Compared with the control group, the group given bupivacaine with epinephrine used significantly less narcotics (P =.008) and had significantly shorter intubation times (P =.003).

* CONCLUSION Injection of intercostal bupivacaine with epinephrine before chest closure in open heart surgery decreases use of narcotics and length of intubation postoperatively, thus speeding up recovery times. (American Journal of Critical Care. 2002; 11:433-435)

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According to the American Heart Association, (1) in 1999, approximately 753 000 open heart surgeries were performed in the United States. For patients who do not have complications, the mean length of stay in the hospital after open heart surgery is 4 to 6 days. The length of stay is driven in part by the duration of intubation after surgery, which may range from 2 to 24 hours or longer. The length of time a patient is intubated is affected by the amount of narcotics given postoperatively for chest discomfort during weaning from mechanical ventilation.

Literature Review

Pain after open heart surgery hinders postoperative care and extubation of patients. Alternative methods of bypass surgery are becoming popular but are not associated with a decrease in postoperative pain. In a recent case study, (2) 0.025% bupivacaine was injected into 2 small catheters placed in the intercostal tissues in a 56-year-old woman after open heart surgery. She was then weaned from mechanical ventilation during a period of 4 hours. The duration of mechanical ventilation was reduced by 33%.

In a study (3) at the Veterans Administration Medical Center, Buffalo, NY, 133 patients who had cardiac surgery were randomized to receive either standard postoperative treatment for pain (ie, intravenous morphine; 69 patients) or intrathecal infusion of opioids (64 patients). Mean age of the patients was 61.3 years. A total of 85% had coronary bypass surgery, 7% had valve repair, and 8% had a combination of bypass surgery and valve repair. Pain was evaluated by using a 0 to 10 visual analog scale, with 0 indicating no pain and 10 indicating the most excruciating pain the patient had ever felt. Compared with the patients who received morphine, patients given intrathecal opioids appeared to be more comfortable upon arrival in the surgical intensive care unit and 24 hours after surgery. They also awakened more quickly and were able to be extubated sooner.

In a double-blind study, Symreng et al (4) compared use of bupivacaine injections with use of isotonic sodium chloride solution in 21 patients (15 men and 6 women) who had chest surgery. The patients received either bupivacaine or isotonic sodium chloride solution via an intrapleural catheter placed during surgery. The patients given bupivacaine had a significant decrease in pain.

In a double-blind, placebo-controlled, crossover study, Dryden et al (5) examined the effect of continuous intercostal infusion of bupivacaine for pain relief in 20 patients after thoracotomy. Patients were given general anesthetic agents in the operating room in the usual fashion according to hospital policy. Once surgery was complete, a catheter was placed in the intercostal space before the chest was closed. Postoperatively, morphine for pain relief was delivered via a patient-controlled pump. Patients were divided into 2 groups. Those in group A were given infusions of bupivacaine via the intercostal catheter for 24 hours and then infusions of isotonic sodium chloride solution for 24 hours; those in group B were given isotonic sodium chloride solution first and then bupivacaine. Pain was evaluated by using a visual analog scale at 1, 3, 6, 24, and 48 hours after the operation. The results indicated that patients used less morphine and had smaller pain scores during the bupivacaine infusion than they did during the infusion of isotonic sodium chloride solution.

The results of these studies indicate that the use of intercostal analgesics reduces postoperative pain. When pain is decreased postoperatively, patients may recover more quickly. In the few studies done to examine this relationship, the results tended to indicate that patients with decreased pain after surgery have shorter recovery times.

Research Hypothesis

We hypothesized that patients would recover more quickly from surgery if postoperative pain was decreased or eliminated. We also hypothesized that infiltration of bupivacaine with epinephrine, a nonnarcotic analgesic, into the intercostal tissues just before closure of the mediastinum after open heart surgery would decrease pain and thus decrease the amount of narcotics used postoperatively. In turn, the decreased use of narcotics would shorten the duration of mechanical ventilation, thus shortening intubation time.

Methods

A double-blind quasi-experimental method was used. Recovery time was measured as the interval from the time of admission to the recovery unit after surgery to extubation. Narcotic usage was the number of doses of narcotics given during intubation.

Sample

The initial sample consisted of 85 cardiac patients who had open heart surgery at Saint Joseph's Regional Medical Center, South Bend, Ind. Of these 85, men and women of any race, 30 to 80 years old, were included in the study if they were predominantly healthy. Patients were excluded from the study if they were having repeat open-heart surgery; had a known sensitivity to bupivacaine or epinephrine; were taking a monoamine oxidase inhibitor or tricyclic antidepressant; had a history of pulmonary disease (eg, chronic obstructive pulmonary disease, emphysema, bronchiolitis, or asthma); had a forced expiratory volume in 1 second less than 1000 mL; or were having emergency open heart surgery. Because of the sample size, other factors (eg, multisystem problems) were not part of the exclusion criteria. Patients who were reintubated within 24 hours after initial extubation (see "Procedure" section) were also excluded.

Procedure

Permission for the study was obtained from the investigational review board of the medical center, which oversees all research involving human subjects. After informed consent was obtained, patients were randomized to 2 groups for treatment with or without bupivacaine. All patients were then taken to the operating room where anesthetic agents were administered by anesthesia personnel. Midsternal incisions were used for coronary bypass surgery and valve surgery.

After surgery, before closure of the chest, patients in the treatment group had the intercostal spaces infiltrated with 20 mL of 0.5% bupivacaine with epinephrine. Patients in the control group received no bupivacaine. The patients in both groups were evaluated for extubation in the cardiac recovery unit by the staff and anesthesiologist. The criteria for extubation were as follows: arterial blood gas analysis: pH greater than 7.35 to less than 7.45, PC[O.sub.2] less than 45 mm Hg, and P[O.sub.2] greater than 65 mm Hg; and weaning parameters: negative inspiratory force greater than-25 and tidal volume 10 mL/kg. After extubation, patients were monitored for respiratory distress and hemodynamic stability up to 24 hours. Patients' use of pain medication and times to extubation were determined.

An independent sample, t test analysis was used to determine if the 2 groups of patients differed significantly in 2 variables: narcotic use and recovery time.

Results

Data on 47 patients were evaluated: 25 patients in the experimental (treated) group and 22 patients in the control (untreated) group. Differences between the treated and untreated groups for use of pain medications and extubation times were significant (see Table). The treated group used less pain medication and had shorter intubation times.

Conclusion

The results indicate that infiltration of bupivacaine with epinephrine into the intercostal spaces before chest closure after open heart surgery decreases intubation times in the recovery room, thus speeding up patients' recovery times. Shorter recovery times result in decreases in hospital length of stay because patients return to normal activity more quickly.

REFERENCES

(1.) Open-heart surgery statistics. In: Heart & Stroke Encyclopedia. American Heart Association Web site. Available at: http://www.americanheart.org/presenter.jhtml?identificr=4674. Accessed June 26, 2002.

(2.) Borges MF, Coulson AS. Minimally invasive coronary bypass surgery: postoperative pain management using intermittent bupivacaine infiltration. Br. J Anatesth, 1998;80:519-520.

(3.) Nader ND, Peppriell JE, Panos AL, Bacon DR. Potential beneficial effects of intrathecal opioids in cardiac surgical patients. Internet J Anesthesiol [serial online]. Vol. 4, No. 2, 2000. Available at: http://www.ispub.com/journals/IJA/Vol4N2/ito.htm. Accessed June 26, 2002.

(4.) Symreng T, Gomez MN, Rossi N. Intrapleural bupivacainc v saline after thoracotomy: effects on pain and lung function, a double-blind study J Cardiothorac Anesth. 1989;3:144-149.

(5.) Dryden CM, McMenemin I, Duthie DJ. Efficacy of continuous intercostal bupivacaine for pain relief after thoracotomy. Br J Anaesth. 1993;70:508-510.

By William J. Fox, RN, BSN, and Thomas A. Hughes, MD. From Saint Joseph Regional Medical Center, South Bend, Ind.

COPYRIGHT 2002 American Association of Critical-Care Nurses
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