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Eur J Cardiothorac Surg 2003;24:588-593
© 2003 Elsevier Science NL
Department of Respiratory Medicine and Thoracic Surgery, Glenfield Hospital, Leicester LE3 9QP, UK
Received 13 March 2003; received in revised form 19 June 2003; accepted 24 June 2003.
* Corresponding author. Tel.: +44-116-2563959; fax: +44-116-2367768
e-mail: ingeroey{at}hotmail.com
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Abstract |
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 Top Abstract 1. Introduction2. Patients and methods3. Results4. DiscussionReferences |
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Key Words: Emphysema • LVRS • Postoperative pain • VATS
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1. Introduction |
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TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionReferences |
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The benefits of LVRS have been reported both in terms of respiratory physiology as well as health status. Disease-specific health status questionnaires have the advantage of being more sensitive to changes but generic instruments measure the impact of LVRS on various different aspects of health status. One of these aspects that affect health status and which is especially relevant after a surgical procedure is pain. Both the Short Form (SF 36) and Euroquol generic health status questionnaires contain questions regarding the degree of pain experienced by the patients [3,4]. Those with worse pain score will have a worse health status score.
Non-randomised studies comparing the degree of acute pain up to 3 weeks after VATS and open thoracotomies, found significant less pain after VATS [5–7]. Studies of the effects of VATS on chronic pain are sporadic but do suggest this occurs less frequent after VATS than after open thoracotomies [8]. None of these studies involve LVRS. As the primary objective of LVRS is to improve health status in patients with severe emphysema we wanted to assess the long-term effect of pain on health status after unilateral VAT LVRS.
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2. Patients and methods |
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TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionReferences |
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2.1. Selection criteria
Patients had to have significant symptomatic dysfunction judged by the modified MRC dyspnoea scale as grade 3–5. Spirometric inclusion criteria consisted of an FEV1 of 15–40% of predicted; residual volume (RV) in excess of 200% of predicted; total lung capacity (TLC) greater than 120% of predicted and a RV/TLC ratio over 60%. Anatomical criteria included the presence of heterogeneous emphysema with target areas of severe emphysema on CT scan. Physiological heterogeneity was assessed on radionuclide scintigraphy. This was quantitated by calculating the so-called Q score as determined by the ratio of perfusion in the target zone to the total lung perfusion [9]. Patients with target areas in either upper or lower lobes were included.
Exclusion criteria included single large bullae, hypercapnia (pCO2 greater than 7 kPa or 53 mmHg), greatly reduced diffusion capacity (KCO less than 25% of predicted).
All patients underwent preoperative pulmonary rehabilitation. Exercise tolerance was assessed using the shuttle walk test. Patients who could not complete a distance of 150 m in a shuttle walk test did not proceed to operation. Rehabilitation was carried out as a 7-week out-patient or 2-week in-patient programme.
Before surgery but after rehabilitation patients completed Form with SF 36 (SF 36, Fig. 1) and Euroquol health status questionnaires (Fig. 1) [3,4]. The Form with SF 36-item questionnaire (SF 36) is a generic health status questionnaire in which 36 questions cover eight health domains; physical functioning, social functioning, role limitations due to physical problems, role limitations due to emotional problems, mental health, energy/vitality, pain and general health status. For each domain scores are transformed to range from 0 (worst possible health status) to 100 (best possible health status). The Euroquol is also a generic questionnaire consisting of five dimensions; mobility, self-care, usual activities, pain and discomfort, anxiety and depression. Each dimension is scored from 1 to 3 (no problem to extreme problem). These scores can be transformed into a single index of health status.
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Surgical approach was though three 2-cm incisions. Flexible ports were used to minimize intra operative trauma (Flexipath, Ethicon Endo Surgery Inc., Cincinnati, OH). All operations entailed stapled resection of functionless areas of lung using pericardial buttresses. After completion of the operation one or two drains 28F were positioned through the VATS incisions and attached to a 5 kPa suction.
All patients had thoracic epidurals inserted in the anaesthetic room prior to their surgical procedures. Redo-operations were also performed with an epidural catheter in situ. The epidural infusion contained fentanyl 5 mcg/ml with bupivacaine 0.1% in 250 ml 0.9% saline. Whilst the patients had an epidural catheter hourly to four-hourly, scoring of the pain was performed using the epidural score (Fig. 1). In three patients epidurals were converted to intra-venous morphine after 2–3 days due to redness around the entrance site of the epidural catheter. In the remaining patients epidurals were weaned gradually depending on the patients’ requirements. Most patients were discharged on a combination of oral analgesia consisting of paracetamol, dihydrocodeine and a non-steroidal anti-inflammatory drug.
2.3. Postoperative follow-up
Patients were reviewed in out-patient clinics at 3, 6, 12 months and then annually after surgery. At each visit, patients underwent detailed spirometry and plethysmography. They also completed SF 36 and Euroquol health status questionnaires.
2.4. Statistical analysis
Data were analysed using SPSS Version 9.0 statistical software. The relationships between preoperative and postoperative variables were assessed using the paired or unpaired Student's t-test and the Wilcoxon test. All P values were reported without corrections for multiple comparisons, a P<0.05 was considered to indicate a statistically significant difference.
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3. Results |
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TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionReferences |
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Nine patients have died since their operation but before their 2-year follow-up. None of the living patients were lost to follow-up but in some patients we were not able to obtain pulmonary function tests or health status questionnaires (admitted to ITU or lived geographically too far away to attend all yearly appointments) (Table 1).
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Median postoperative stay was 14 (6–197) days. Median duration of drain stay was 13 (40) days. Median duration of epidural was 6 (2–40) days. Thirty-day mortality was 2%. This patient died of sudden bleeding after removal of a chest drain.
3.3. Postoperative changes in respiratory physiology
Table 2 shows the postoperative changes in pulmonary physiology. The reduction in hyperinflation remains significant at least 2 years after LVRS.
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There was no significant correlation with the changes in pain score, as measured with both questionnaires, and age or gender. There was also no correlation with the duration of the operation or whether one or two drains were inserted at the time of surgery and how long these drains were left in situ. No correlation was found with epidural time or total postoperative hospital stay. No correlation was found with the epidural score.
Ten patients had an extra procedure, i.e. open thoracotomy (with possible insertion of a chest drain prior to surgery) or only an insertion of a chest drain. Three of the five patients who had a thoracotomy and one of the five patients who had an additional drain inserted died before 3 months follow-up. The six remaining patients did not have more frequently a worsening of their pain score than those patients without an extra procedure (Table 4).
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There was an increase in body mass index (BMI), which was significant from 6 months up to 2 years. The best improvements were obtained 12 months after surgery (BMI increased from 23 (4) kg/m2 preoperatively to 24 (4) kg/m2, P<0.01). There were also low but statistically significant correlations between the changes in BMI and changes in pain scores at 3 and 6 months (R=-0.37 at 3 months, R=-0. 32 at 6 months for Euroquol, R=0.32 at 3 months for SF 36).
Significant correlations were found between preoperative pain score and the subsequent changes in pain score. Of those who had the best preoperative scores (80–100% as measured with the SF 36) the majority had a worsening score. Of those who had the worse preoperative scores the majority improved their scores (Fig. 3) .
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4. Discussion |
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TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionReferences |
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There are few studies evaluating the effects of VATS on long-term pain. It is difficult to compare these studies. They often consist of different patient groups, use different methods of assessing pain and at different time intervals.
Stammberger's study of 173 patients, evaluating the early and long-term pain complaints after VATS, did find that in many patients the pain was of a shorter duration than in our study (Table 3) [10]. However, this was a retrospective study, using only one self-reported questionnaire on a heterogeneous group of patients undergoing a variety of surgical procedures. Passlick looked at a group of 60 patients who had a VATS procedure for spontaneous pneumothorax and found that after a median follow-up of 59 months 32% still experienced chronic pain [11]. Hutter also found chronic sequelae (pain in 20.1%, as well as numbness and dysaesthesia) in 31.4% at least 2 months after thoracocscopy for benign disease [12]. Also, after lobectomies for malignant tumours VATS was found to cause less acute and chronic pain compared to thoracotomies [8].
In our study we found different results depending on which questionnaire we used. The reason more patients have a worsening pain score as measured with SF 36 may be due to its higher sensitivity to measure smaller changes. The Euroquol questionnaire has only one question related to pain with three possible answers, while the SF 36 has two questions with each five or six possible answers. Nevertheless, a standardised health status questionnaire may be a better way of assessing the duration of pain rather than a self-reported duration of pain.
Long-term pain after thoracotomy is common, occurring up to 50% after 2 years. It seems from our study as well as others that this is also a problem after VATS. The next step would be to find out what predicts postoperative pain and how to reduce it. Katz found early postoperative pain the only factor that predicted long-term pain [13]. We found no correlation between the epidural score or duration of epidural used in the acute postoperative period and the long-term changes in pain scores. It may be that the routine use of epidurals avoids too severe pain in the early period, thereby eliminating this risk factor for subsequent pain.
Hutter found a significant correlation whether one or two drains were used [12]. We found no such correlation. Again, this may be related to our routine use of postoperative epidural for pain relief; the usual difference in pain experienced with one or two drains in situ may have been eliminated.
Our population differs from the other studies in that all our patients have severe emphysema. In a group of hospitalised patients with advanced COPD 21% was reported to have severe pain [14]. Pain in patients with emphysema has been found to correlate with FEV1/FVC [15]. However, we found no such correlation. The fact that patients with emphysema can suffer from severe pain may also be a contributing factor that we have failed in our study to show that adequate control in the acute period is related to the avoidance of long-term pain.
We found no correlation with the preoperative BMI and the subsequent change in pain scores. There were some correlations between the subsequent improvements in BMI and the improvements in pain scores. It may be that patients who have less pain are able to eat better and so increase their BMI. It has been found that LVRS increases BMI, however, probably not related to increased intake of food [16]. It may be that those with improved BMI have a different chest wall configuration causing less strain on musculo-skeletal structures. This may also be the mechanism behind the observation that there seems to be some correlation between changes in RV and changes in pain score.
As regards to the correlation between preoperative pain scores and subsequent pain score; obviously those patients with a 100% score are not able to improve their score even further. Those who already have a low pain score, the added pain of the operation may not influence the score much. It becomes less clear why these patients often improve their scores post LVRS.
Various anaesthetic and surgical techniques have been described to reduce acute postoperative pain after VATS. It is doubtful whether alternative analgesic methods, such as intraoperative blocks and transcutaneous electrical nerve stimulation [17,18] would add any benefit, as all our patients already have epidural analgesia. Senturk's randomised study comparing three different analgesia techniques (thoracic epidural analgesia with or without preoperative initiation and intra-venous patient-controlled analgesia) found that preoperatively initiated thoracic epidural analgesia was most effective in controlling pain in the acute and long-term period [19].
We use flexible surgical ports to minimize intra operative trauma. Other techniques described include the localized partial rib resection and the placements of all instruments along one intercostal space. However, the reported study was only on nine patients and it may be technically less useful in a more complicated procedure as LVRS [20]. Still in an experimental stage but potentially a solution to prevent post-VATS pain is bronchoscopic LVRS. Several techniques have been described. Ingenito's group reports on the favourable results of an animal study in which hyperinflated lung is transformed into contracted scar tissue after installation of various solutions into the bronchi [21]. Lausberg's ex vivo study in human lungs involves the placement of stents between pulmonary parenchyma and large airways to improve expiratory flow [22].
Perhaps the best solution of managing post-VATS pain at present is the more frequent and earlier referral of patients to a specialized pain clinic. For post-thoracotomy pain posterior multidermatomal intercostal nerve blocks, epidural blocks and paravertebral blocks have all been used with success [23].
Some of the heath status benefit of LVRS is offset by postoperative pain and it is important to inform patients about this possibility. It would be interesting to compare this group of LVRS patients with our other patients who undergo VATS, who we do not routinely use flexible port on, and who do not have routinely epidural pain relief. Their drain stay as well as their total hospital stay tends to be shorter.
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Footnotes |
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References |
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TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionReferences |
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