Comparison of effects of epidural bupivacaine and intravenous meperidine analgesia on patient recovery following elective abdominal aortic surgery

Background

In patients undergoing surgery, multiple factors have been reported to affect postoperative recovery and discharge condition of the patient. Despite advances in anesthesia, surgery, and postoperative care, the adverse effects of postoperative pain on recovery could not be prevented. In recent years, a ‘stress-free anesthesia and surgery’ strategy has been developed to avoid these adverse effects and to decrease surgical morbidity and mortality [1]. Efforts to decrease postoperative stress by means of postoperative pain management are employed to prevent catabolic state and organ dysfunction caused by endocrine-metabolic and inflammatory mediators [2].

Studies aiming to decrease surgical stress have documented the importance of anesthesia strategy. Epidural anesthesia and analgesia were reported to be very effective in decreasing perioperative surgical stress and surgical complications, and improving recovery [3,4].

In this prospective study, we aimed to compare the effects of epidural bupivacaine and intravenous meperidine on quality of recovery and postoperative outcomes in patients undergoing elective abdominal aortic surgery with general anesthesia for abdominal aortic aneurysm (AAA) repair or aortoiliac occlusive disease.

Material and Methods

OPERATIVE STRATEGY:

Transperitoneal approach was performed in every patient. Aortic graft interposition procedure was performed in AAA cases. In cases with aortoiliac occlusive disease, bilateral groin incisions were made for exploring femoral arteries, and aortobifemoral bypass procedure was performed. Dacron vascular grafts were used in every patient. A postoperative drain was not inserted into the retroperitoneal area.

POSTOPERATIVE ANALGESIA:

In the intravenous group, for patient-controlled analgesia (PCA) (Abbott Pain Management Provider™ Abbott Laboratories, North Chicago, IL, 60064, USA), a solution of meperidine (Aldolan^®, Liba Ilac Laboratuvarları A.S, Istanbul, Turkey) with a concentration of 5 mg/ml was prepared; lock-out was set as 10 minutes, and loading and infusion doses were set as 0.1ml/kg. In the epidural group, PCA was maintained as follows: a solution of bupivacaine (Marcaine^®, Astra-Zeneca Ilac Sanayi, Istanbul, Turkey) with a concentration of 1.25 mg/ml was prepared; lock-out was set as 20 minutes, and loading and infusion doses were set as 0.1 ml/kg. In both groups, patients were given bolus doses at the end of surgery and taken to the intensive care unit (ICU), and PCA was initiated and continued for 3 days. Patients were sedated with 5 mg/kg/hour propofol until extubation, and 500 mg acetaminophen 3 times a day was administered for 3 days. After cessation of PCA in both groups, 500 mg of acetaminophen was administered if required.

Extubation criteria were: ability to respond to verbal stimuli, body temperature >36.5°C, PO2 >70 mm Hg, PCO2 <50 mm Hg, and rate of respiration <20/min or pressure-aided ventilation <10 cm H₂O and stable hemodynamics.

All patients were mobile on postoperative day 1, all had mobility scores over or equal to 6 and all recordings within the first 3 postoperative days were noted. Mobility scores were graded as: 0, not able to move; 1, able to sit in bed; 2, able to stand in bed; 3, able to walk 25 m; 4, able to walk 50 m; 5, able to walk 75 m; 6, able to walk more than 100 m; 7, able to walk more than 100 m and able to climb 1 flight of stairs; and 8, able to walk more than 100 m and able to climb 2 flights of stairs [5].

In the first 3 postoperative days, pain was monitored using the visual analogue scale (VAS) [6,7] and sedation was monitored by a 4-point sedation scale [8]. The 4-point sedation scale was graded as 0: fully awake, 1: mild sedation (drowsy, but easily awakened), 2: moderate sedation (mostly sleepy, but easily awakened), 3: severe sedation (somnolence, awakened with difficulty).

Oral intake was initiated based on physical examination findings. When passage of flatus was observed and bowel motility was evaluated as satisfactory by the physician, the nasogastric tube was removed. Oral intake was initiated with fluids and progressively solid diet was given.

Discharge criteria were: hemodynamic stability without arrhythmia, freely mobile and able to eat without any help, absence of fever and clinical manifestations of infection, normal urination and defecation, analgesia maintained with or without analgesics, able to walk more than 100 meters, able to climb more than 2 flights of stairs, and normal mental state.

STATISTICAL ANALYSIS:

Statistical analyses were performed using SPSS software for Windows version 17.0 (Statistical Package for the Social Sciences Inc, Chicago, IL, USA). Continuous variables were expressed as ‘mean values ± standard deviation (SD)’. Categorical variables were expressed as number and percentages. Demographic characteristics and outcomes of the groups were compared using independent samples t-test for continuous variables, and, chi-square test and Fisher’s exact test for categorical variables. Statistical significance was set as p<0.05.

Results

Eighty patients were included in the study; 40 were administered epidural bupivacaine (epidural group) and 40 were administered intravenous meperidine (intravenous group) PCA. The mean age of the patients was 61.7±8.1 in the epidural group and 59.4±9.7 in the intravenous group (p>0.05). The male: female ratio was 39: 1 in the epidural group and 38: 2 in the intravenous group (p>0.05). The preoperative demographic characteristics of the patients are shown in Table 1.

When intraoperative variables and postoperative outcomes were compared, anesthesia time, intubation time, ICU stay, hospital length of stay, and postoperative vomiting prevalence were similar between the groups. Postoperative myocardial infarction, renal failure, and stroke rates were not different between the groups. Postoperative nausea was more common in the intravenous group. In the epidural group, time to begin oral intake was shorter, mobility scores were higher, and sedation scores and VAS were lower during the first three postoperative days (p<0.05 each) (Table 2).

No complications related with epidural protocol (e.g., hematoma formation or infection) were observed during the study period. No mortality was observed during the study period.

Discussion

LIMITATIONS:

The study included patients with 2 different groups of pathologies: AAA and aortoiliac disease. The burden of peripheral arterial disease, which can affect postoperative pain depending on the extent of the disease, was not taken into account while evaluating the results.

Conclusions

Postoperative pain following abdominal aortic surgery is a major issue that causes patient discomfort and delays mobility and oral intake. Strategies for postoperative pain management will provide earlier mobility, nutrition, and improve recovery. Epidural analgesia allows earlier mobility and less sedation, but does not affect postoperative complication rates, intubation times, or ICU and hospital length of stay.