15th October 2010, Volume 123 Number 1324

Ei Thu Aung, Pascale Fluri, Semisi Aiono

Effective pain relief plays a crucial role in fast recovery from abdominal surgery. There are various modalities of pain relief used after abdominal surgery. The main methods are patient controlled analgesia (PCA) using either morphine or fentanyl, epidural and combination of both PCA and epidural.
There has been an introduction of innovative pain relief using continuous regional analgesia via wound catheters in recent years.9 It involves placing catheters such as those used in nerve blocks directly into the rectus sheath during laparotomy. The catheters are then infused with local anaesthesia as continuous infusion.
At our hospital in Wanganui, this method was introduced since late 2007. Wound catheters are inserted into the midline fascia into the space between rectus muscle and posterior rectus sheath before closure of deep fascia (Picture1). They are infused with loading dose of 0.75% ropivacaine after placement of wound catheters during the operation, followed by continuous infusion of 0.2% ropivacaine at 5ml/hour after the operation. The infusion was given via a set of infusion bottles premixed with ropivacaine using elastomeric pump system (Baxter) (Picture 2).
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One set of infusion bottles usually lasts for 48 hours. Wound catheters are used in addition to PCA of morphine or fentanyl. A recent review found the benefits from using wound catheters including improved analgesia, reduced opioid use and side effects, increased patient satisfaction, and decreased hospital stay.3,4,7,10
The aim of our study is to review the effectiveness of using rectus sheath wound catheters as pain relief in abdominal surgery in a New Zealand district general hospital.

Methods

A retrospective case series was carried out on patients who underwent midline laparotomy from April, 2008 to December, 2008. The data was collected from theatre lists by selecting patients who underwent laparotomy either electively or as an emergency. It was collected for audit following the guidelines of the health information privacy code. Decision to put rectus sheath catheters is based on consultant’s preference.
Required data was extracted from patients ‘medical records. We collected pain scores at rest and on mobilization within 24 hours post operatively. Pain scores were obtained from standard pain score charts used for PCA, Epidural or wound catheters. On our charts, pain scores were divided into 4 categories. They are nil (0), mild (1–2), moderate (3–6), and severe (7–10). We also recorded the time required to finish a syringe of PCA.
In our hospital, a standard morphine PCA contains 50 mg of morphine in a syringe and fentanyl PCA contains 1000 mcg in one syringe. We decided to use time required to finish a syringe of PCA as a parameter instead of amount of analgesic used due to different types and dosages of opiates used in PCA. Complications such as wound infection, PCA or epidural-related side effects were documented.

Results

A total of 86 operations were identified. Out of 86 operations, 54 operations were included in the study. The reasons for exclusions were non laparotomy operations (such as appendicetomy, open cholecystectomy), 2nd laparotomies (only 1st laparotomies were included), and non-documentation of pain scores.
There were 27 in the wound catheter and PCA group, 15 in the PCA only group, 12 in the epidural and/or PCA combined group. 24 emergency operations and 31 elective operations were performed during our retrospective study period. The majority of surgeries had large bowel resections (33/54) and most of laparotomies were for malignancy (Table 1).
There were 4 wound infections with 2 in wound catheter group, 1 in PCA group and 1 in epidural group. In epidural group, 4 out of 12 patients were noted to have blockage or failure of catheters requiring early removal and switching to PCA.
Table 1. Patient demographics
Variables
Wound catheter+PCA
PCA
Epidural±PCA
n =
female
male
Age range:
<40
40–59
60–79
≥80
acute
elective
Colon resection
upper GI
others
tumour
no tumour
27
9
18
1
7
13
6
11
16
17
6
4
20
7
15
8
7
8
6
1
8
7
6
3
6
6
9
12
6
6
2
9
1
5
7
10
1
1
9
3
Table 2. Pain scores for different analgesic groups
Pain score
Wound catheter+PCA
PCA
Epidural±PCA
Total
27
15
12
At rest
nil
mild
mod
severe

18 (66.70%)
9 (33.30%)
0
0

9 (60.00%)
6 (40.00%)
0
0

5 (41.7%)
5 (41.7%)
1 (8.3%)
1 (8.3%)
Mobilisation
nil
mild
mod
severe

3 (11.10%)
19 (70.40%)
5 (18. 50%)
0

0
9 (60.00%)
6 (40.00%)
0

2 (16.7%)
5 (41.7%)
4 (33.3%)
1(8.3%)
Time for 1st syringe of PCA
≤24 hour
>24 hour
9 (33.30%)
18 (66.70%)
9 (60.00%)
6 (40.00%)
3 (38%)
5 (63%)
Complications
Wound catheter+PCA
PCA
Epidural±PCA
Total
Wound infection
Blockage of epidural catheter
Catheter infection
2

0
1

0
1
4
0
4
4
0
The pain scores for different groups were shown in Table 2. In wound catheter group, 66.7% patients had no pain at rest, 33.3% had mild pain at rest and none in the group had moderate to severe pain at rest.
On mobilisation, 70.4% had mild pain and only 18.5% had moderate pain in wound catheter group. In contrast, 33.3% in epidural group and 40% in PCA group had moderate pain on mobilisation. (Figure 1 and Figure 2)
In epidural and/or PCA group, there were 8 who had PCA in addition to epidural. On calculating the time needed to finish a 1st syringe of PCA, we had only included 8 patients who had PCAs. We found that, a syringe of PCA containing either 50 mg morphine or 1000 mcg of fentanyl lasted more than 24 hours in 66.7% of wound catheter group (Figure 3).
Analysis using 1-way ANOVA showed no difference between 3 groups in all 3 measures. P-values for the 3 measures are as below.
  • Pain at rest p=0.6,
  • Pain on mobilisation p=0.6, and
  • Time needed to finish a PCA syringe p=0.23.
Figure 1. Pain scores at rest
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Figure 2. Pain scores on mobilisation
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Figure 3. Time required to finish one PCA syringe
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Discussion

Our case series analysis showed that infusion of local anaesthetic agents via wound catheters provided a safe and adequate alternative pain relief method. Our results showed better pain control on mobilisation in comparison to other established postoperative analgesics. It also reduced the amount of opiates used post operatively. Having catheters connected to small bottles of local anaesthesia had a great advantage in improving mobility. Adverse outcomes were not significantly higher in wound catheter group. Although the results were not statistically significant, the outcomes were not worse than PCA or epidural groups.
Pain relief after abdominal surgery is usually provided in a multimodal approach. In our hospital, PCA and regional anaesthesia via epidural infusion have been the accepted methods. However, the delivery of epidural anaesthesia requires close supervision and monitoring by nursing and medical staff. Moreover, there are common complications of epidural blocks such as severe hypotension, and reduced mobility (less commonly infection, or nerve injury). This had led us to the use of another safe and simpler alternative pain relief using local anaesthesia via wound catheters.
The wound catheters have been used most frequently for patients who have undergone orthopaedic or "sports medicine" surgery to repair knee and shoulder problems.6 Some studies showed reduced length of hospital stay associated with continuous wound catheters, especially in the cardiothoracic and orthopaedic surgery subgroups.There are not many studies on efficacy of rectus sheath catheters in abdominal surgery. The literature reviews on use of wound catheters in abdominal surgery showed mixed results. A randomised controlled study by Polglase, et al (2007) showed minimal benefit of wound catheters compared with saline infusion in colorectal surgeries.1
An audit done in Tasmania by Blackford, et al (2007) showed reduced pain at rest and on mobilisation using wound catheters in the first four postoperative days.8A systemic review of randomised controlled trials using wound catheters (RCTs) by Liu, et al (2006) reported that most RCTs (10 out of 12) showed significant analgesic efficacy by either reduced opiate use or reduced pain scores in general surgical operations.4
There were a few flaws in our study. It was a retrospective audit with small sample size. The number of patients was not equal in each group. We had included all laparotomies with mixed pathologies and indications with mixed surgical techniques in our study which was one of the confounding factors in our study. A prospective study comparing local anesthaesia via wound catheter with either PCA or epidural for patients undergoing a specific abdominal surgery (e.g. colorectal surgery) should be conducted to evaluate the efficacy.
Conclusion—Local anesthaesia via wound catheters is a relatively safe and effective pain relief. It allows easy step down from high dependency unit to general ward, facilitating fast track recovery in abdominal surgery. It is feasible in smaller hospitals.

Summary

This study reviewed the effectiveness of continuous regional analgesia (CRA) via wound catheters after abdominal surgery in a district general hospital (Wanganui). Results showed that CRA via wound catheters provides effective and safe analgesia (pain relief) after abdominal surgery for patients in a small district general hospital. This technique was readily accepted by theatre, HDU, ward, and anaesthetics colleagues in the hospital.

Abstract

Aim

To review the effectiveness of continuous regional analgesia (CRA) via wound catheters after abdominal surgery in a district general hospital (Wanganui, New Zealand).

Method

Retrospective review of postoperative analgesia after CRA via wound catheters was introduced (April 2008 to December 2008). Pain scores, HDU stay, opiate use and complications were recorded.

Results

Fifty-four patients’ notes have been reviewed after elective and emergency laparotomies. Twenty-seven had WC (± patient controlled analgesia [PCA]), 15 had PCA only, 12 had epidural (± PCA). Resting pain scores were nil or zero in 18/27 (66.7%) wound catheter, 9/15 (60%) PCA and 5/12 (41.7%) epidural patients. Moderate/severe pain on movement was scored in patients 5/27 (18.5%) with wound catheter, 6/15 (40%) with PCA, 5/12 (41.7%) with epidural catheters. A single PCA syringe lasted over 24 hours in 18/27 (66.7%) wound catheter, 6/15 (40%) PCA, and 5/8 (63%) epidural + PCA patients. Eight adverse effects were seen; 4 wound infections (2 wound catheter, 1 PCA, 1 epidural patient) and 4 blockages of epidural catheters in epidural group. No adverse effect was found directly related to the WC.

Conclusion

Continuous regional analgesia via wound catheters provides effective and safe postoperative analgesia for surgical patients in a small district general hospital. Used as part of a multimodal approach it allows easy step-down from HDU to surgical wards. This technique has been readily accepted over the year by theatre, HDU, ward, and anaesthetics colleagues.

Author Information

Ei Thu Aung, Surgical Registrar; Pascale Fluri, Surgical Registrar; Semisi Aiono, Consultant Surgeon; Department of Surgery, Wanganui Hospital, Wanganui

Correspondence

Ei Thu Aung, Surgical Registrar, 100 Heads Road, Wanganui Hospital, Wanganui, New Zealand.

Correspondence Email

etaung@yahoo.com

Competing Interests

None.

References

  1. Polglase AL, McMurrick PJ, Simpson PJ, et al. Continuous wound infusion of local anesthetic for the control of pain after elective abdominal colorectal surgery. Dis Colon Rectum 2007;50:2158–2167.
  2. Cheong WK, Seow-Choen F, Eu W, et al. Randomized clinical trial of local bupivacaine perfusion versus parenteral morphine infusion for pain relief after laparotomy. Br J Surg. 2001;88(3):357–359.
  3. Karthikesalingam A, Walsh SR, Markar SR, et al. Continuous wound infusion of local anaesthetic agents following colorectal surgery: Systematic review and meta-analysis. World J Gastroenterol 2008 September 14;14(34):5301–5305.
  4. Spencer S, Liu J, Richman M, et al. Efficacy of Continuous Wound Catheters Delivering Local Anesthetic for Postoperative Analgesia: A Quantitative and Qualitative Systematic Review of Randomized Controlled Trials. American College of Surgeons 2006.08.007, ISSN 1072-7515/06.
  5. Sanchez B, Waxman K, Tatevossian R, et al. Local anesthetic infusion pumps improve postoperative pain after inguinal hernia repair: A randomized trial. Am Surg. 2004;70(11):1002–1006.
  6. Clinical policy bulletin, Anesthetic infusion pumps, AETNA, policy number 0607.
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  8. Blackford D, Chivers C, Robertson I. Wound Catheter Infusion of Local Anaesthetic for Upper Abdominal Laparotomy. ANZCA Annual scientific meeting. 2007. 25th May to 27th May, Melbourne, Australia.
  9. Cornish P, Deacon A. Rectus sheath catheters for continuous analgesia after upper abdominal surgery. ANZ journal 2007; Jan-Feb,77(1-2):84
  10. Beaussier M, El'Ayoubi H, Schiffer E, et al. Continuous preperitoneal infusion of ropivacaine provides effective analgesia and accelerates recovery after colorectal surgery: a randomized, double-blind, placebo-controlled study. Anesthesiology. 2007 Sep;107(3):461–8.