Assessment of postoperative pain management and comparison of effectiveness of pain relief treatment involving paravertebral block and thoracic epidural analgesia in patients undergoing posterolateral thoracotomy

PVB was performed in the case of patients premedicated with 7.5 mg oral midazolam. It was performed in sitting position, according to slightly modified technique provided for by Cousin and Bridenbaugh [12]. Epidural catheter was placed in the paravertebral area at the level of the lower edge of the spinous process Th4/Th5 ca. 2.5 cm laterally from the spinous process, depending on the planned surgical incision. Catheter was placed in the paravertebral area at a depth of 3-4 cm. Thereafter, 0.5% bupivacaini in the total volume from 15 to 25 ml was injected prior to analgesia induction. After completion of the procedure, patients were given additional 15 ml of 0.25% bupivacaini. After being transferred to the department of thoracic surgeries the patients were given continuous infusion of 0.25% bupivacaini at the dose of 0.1 ml per kilogram of body weight (5-8 ml per hour).

The second group involved patients who, prior to the posterolateral thoracotomy, were given epidural analgesia performed in the sitting position applying the “hanging drop” technique at the level of Th5/Th6 in the medial body line. Upon identification of the epidural area, an epidural catheter was inserted through Tuohy needle about 4 to 5 cm into the epidural space. Thereafter, test dose of 2 ml of 1% lidocaine was injected to exclude spinal anesthesia. Then from 6 to 8 ml of 0.5% bupivacaini with 0.05 mg of fentanyl was injected. Analgesia induction (in the case of both groups of patients) involved intravenous injection of propofol at the dose of 2 mg per kilogram of the body weight, fentanyl 0.1 mg, cisatracurium at the dose of 0.15 mg per kilogram of the body weight. Patients were intubated with two-channel tube. Analgesia was maintained with respiratory mixture of sevoflurane, nitrous oxide and oxygen in commonly used concentrations. Upon completion of the procedure, patients were additionally given 6-8 ml of 0.5 % bupivacaini to epidural catheter. After being transferred to the Department of Thoracic Surgery the patients were given continuous infusion of 0.125% bupivacaini in the volume of 0.1 ml per kilogram of the body weight (6-8 ml per hour) and fentanyl at the dose of 2 micrograms per ml for 72 hours.

All patients were administered nasal oxygen with the flow of 3 liters per minute, for 24 hours. Patients were provided with continuous monitoring of vital signs: saturation (SpO2), systolic and diastolic blood pressure, pulse, number of breaths, consciousness.

Patients from each of the groups underwent posterolateral thoracotomy and resection of pulmonary parenchyma mainly due to lung tumor, but also due to the presence of emphysematous bulla, diagnosed based on the typical diagnostic methods, the same for both groups.

Patients qualified to the study were randomized to particular groups (simple randomization).

Exclusion criteria included: failure to obtain the patient’s consent, clotting disturbances making it impossible to perform regional analgesia, infection in the area of planned catheter insertion, significant spinal column deformation, difficulties with proper pain severity assessment and T4-infiltrating tumors with continuous pain.

The study was performed in each of the groups according to the same schedule. Measurements had been performed for first three days after the procedure.

Each group had evaluations of SpO2 every 4 hours, arterial blood pressure and pulse every 4 hours, assessment of pain (NRS) every 4 hours, anesthetized area every 4 hours, the use of additional pain relievers, Clinical Quality Indicators in Postoperative Pain Management.

Values regarding current pain in NRS scale (0-10 pints), the highest level of pain within the last 24 hours (0-10 pints), the lowest level of pain within the last 24 hours (0-10 pints) were marked on the linear scale in the same intervals in the scale of 0-10 points. Satisfaction with the manner of postoperative pain management was assessed using the scale of 1-10 points.

Clinical Quality Indicators in Postoperative Pain Management scale was used to assess satisfaction with postoperative pain relieving treatment and quality of the postoperative pain management.

Clinical Quality Indicators in Postoperative Pain Management scale allows to assess satisfaction with postoperative pain relieving treatment and quality of the postoperative pain management, however Visual Analog Scale (VAS) and Numeric Pain Rating Scale (NRS) are the simplest and most often used to assess pain. Clinical Quality Indicators in Postoperative Pain Management, a scale developed by Swedish author, Eva Idvall, enables assessment of many various aspects of postoperative pain management quality [13]. This scale was most of all developed to assess satisfaction with nursing care, but is also used to perform general assessment of postoperative pain management quality. It was translated, among others, to Polish and adopted to local conditions. Assessment with the use of Clinical Quality Indicators in Postoperative Pain Management scale is performed according to 5-point Likert scale, where 1 point means “strongly disagree”, and 5 points mean “strongly agree”. This scale involves also assessment of the highest and the lowest level of pain during the postoperative period within the last 24 hours, assessment of current postoperative pain, similarly to NRS (in the scale of 0-10), assessment of general satisfaction with postoperative pain management in the scale of 1-10 [14].

Anesthetized area, i.e. extent of the sensory blockade, was determined based on the number of anesthetized spinal segments according to the anatomic scheme.

Collected data was subject to statistical analysis performed with the use of SPSS package (SPSS Inc., Chicago IL, USA).

T-test for dependent groups and Mann-Whitney U test were used in statistical analysis. Statistical calculations were performed applying the statistical significance of 0.05.

There were additional pain relievers (morphine, metamizole, ketoprofen, paracetamol) with basic analgesia method (PVB or TEA), while in the case of some patients combination of these drugs was used (Table 7).

Morphine and other pain relievers, such as paracetamol or ketoprofen were used more often in PVB group, while metamizole was more often used in TEA group; however, there was no statistical difference in terms of the use of additional pain relievers between the groups.

Partial spinal anesthesia with symptoms of paraplegia involving all body segments from Th4 downwards, was observed in one patient from TEA group. The patient has not lost consciousness or respiratory efficiency, because upon occurrence of the first symptoms of spinal anesthesia “epidural” infusion of 0.125% bupivacaini was stopped and the epidural catheter was removed. Symptoms of spinal anaesthesia resolved within four hours. MRI of thoracic spine was performed. No damage to the spinal cord was observed. No neurological consequences have been observed in the patient. Upon completion of the treatment, the patient was discharged home in good general condition.

Systolic and diastolic pressure on particular three days after the surgery were similar in both groups. Statistically significant increase of systolic and diastolic pressure values between the first and the third day, and the second and the third day, as well as increase in the heart rate values between the first and the second day and the first and the third day has been observed for both groups analysed altogether. Statically significant increase of systolic pressure values between the first and the third day and the second and the third day as well as increase of the diastolic pressure values between the first and the third day have been observed in the PVB group. Statistically significant increase of diastolic pressure values between the first and the third day and the second and the third day after the surgery was observed in the TEA group. There was no statistically significant difference in the mean values of heart activity between particular days after the surgery in PVB group, while in TEA group statistically significant increase of mean values of heart activity has been observed between the first and the second day and the first and the third day after the surgery; however, on particular days after the surgery both groups were not statistically significantly different in respect of heart rate. Egyptian authors observed significant decrease in arterial blood pressure values in TEA group compared to patients treated with PVB. Similarly, Davies et al. and authors from India stated that TEA causes more evident arterial blood pressure decrease compared to PVB, what results from the fact that TEA has a greater impact on sympathetic system compared to PVB [10, 16, 18]. Studies performed by Szebla et al. also showed non-substantial impact of administration of medicines used for conduction anesthesia to the paravertebral area in the thoracic segment on the basic hemodynamic parameters [19].

Statistically significant decrease in arterial blood saturation between the first and the second day after the surgery and between the first and the third day was observed in the PVB group. Statistically significant decrease in saturation in TEA group was observed between the first and the second day after the surgery. On respective days the groups showed no statistically significant difference in respect of saturation values changes. For both groups altogether, statistically significant decrease in saturation values were observed between the first and the second day and the first and the third day after the surgery. These observations differ from the ones of Richardson et al. (Richardson et al., 1999), where saturation in PVB group was significantly higher in the follow-up period exceeding 48 hours than in the case of TEA group [9].

Additional pain relievers were used in both study groups. Morphine, metamizole and other pain relievers, mainly acetaminofen or ketoprofen, were used in the same administration.

In the case of PVB group morphine was twice as likely often and medicines from other groups were slightly less often used compared to TEA group, while metamizole was more often used in TEA group compared to PVB group. No statistically significant differences have been observed between the groups in terms of the need to use additional pain relievers; however, patients from PVB group needed them a bit more often. Authors from India have similar observations - their study showed no statistically significant difference in terms of use of Morphine (it was the only one additional drug) between PVB and TEA groups [18]. In the study conducted by Messina et al., morphine was statistically significantly more often used in PVB group than in TEA group, while in the study performed by Pintarica et al., the need to use morphine was similar in PVB and TEA groups [20, 21]. Similarly, the study conducted by Okajima et al. showed no statistically significant difference in terms of use of additional pain relievers between PVB and TEA group (p = 0.26) [11]. In the study conducted by Komatsu, 17.6% of patients who were treated with PVB needed additional pain relievers [22].

In our own studies complications were more often observed in TEA group than in PVB group. In PVB group complications were observed in 4 persons, i.e. in 13.3% of the group, while in TEA group complications were observed in 7 persons, i.e. in 23.3%; however the difference in respect of frequency of complications between the study groups was not statistically significant. Complications in PVB group were more often related to catheter and included, among others, leaking of drug outside the catheter or catheter coming out, rather than general complications (e.g. decrease in arterial blood pressure).

In TEA group there were no complications such as hematoma or epidural empyema or damage to nerves. Partial spinal anesthesia with symptoms of paraplegia involving all body segments from Th4 downwards was observed in one patient from TEA group. Symptoms of spinal anesthesia resolved within four hours. Many authors, among others Davies et al. or Baidya et al., emphasize that PVB has in general less complications than TEA, what involves less complications such as decrease in arterial blood pressure, hypoxia, nausea and vomiting or postoperative respiratory failure or pneumonia [1, 10]. Japanese authors in their studies involving patients treated with PVB observed, among others, such complications as atrial fibrillation or respiratory failure requiring mechanical ventilation, but these were single cases [23]. Similarly – also in single cases - occurrence of atrial fibrillation or respiratory failure among the treated patients was observed.

In the conducted studies we have observed comparable severity of pain in both groups. In the studies conducted by Szebla and Machała, who also used NRS to compare pain in PVB and TEA groups, NRS values in both groups were similar and the result was below 3 [8]. Tsuboshima et al. analyzed pain ailments in patients undergoing thoracoscopic surgeries of idiopathic pneumothorax, who were treated with PVB. Pain ailments were assessed using NRS - average NRS value after 6 hours amounted to 2.3 point, after 24 hours after the surgery it was 2.2 points, and after 48 hours it was 1 point - it was less than in our studies, what could result from the use of minimally invasive method and from the smaller extent of the surgery [24].

Majority of authors assessing postoperative pain uses VAS. In the study conducted by Richardson et al., for example, VAS value was statistically significantly lower in PVB group than in TEA group (p = 0.02). While, in the meta-analysis of Ding et al. there were no statistically significant differences in VAS values between PVB and TEA groups at 4-8 hours after the surgery (p = 0.19), 24 hours after the surgery (0.77) and 48 hours after the surgery (p = 0.19) [3, 9].

In the study conducted by Japanese authors, there were no differences between PVB and TEA groups in terms of pain ailments assessed using VRS (Verbal Rating Scale) [11].

In the conducted studies it was assessed if the type of regional postoperative analgesia in chest surgeries affects the number of days of the patient’s stay at the hospital. Statistically significant difference in the number of days of hospitalization between PVB and TEA groups has not been observed.

However, Elsayed et al. observed statistically significant difference between the time of hospitalization of patients who were treated with PVB compared to TEA patients (p = 0.008) of 1 day (6 days vs. 7 days) - time of hospitalization of patients treated with PVB was 1 day shorter and based on this observation they suggested that PVB can become an element of the so called fast track management in chest surgeries. However, this requires further research and improvement of PVB technique [25].

Assessment of patients’ satisfaction with pain management was performed based on the Clinical Quality Indicators in Postoperative Pain Management scale, translated into Polish and adopted to local conditions [13, 14]. Among aspects indicated on the said scale, methods of analgesia being compared in the study, i.e. PVB and TEA, were statistically significantly different only in respect of the category “the lowest level of pain within the last 24 h” in the scale of 0-10 points. Result in TEA group was statistically significantly lower than the one in PVB group (p = 0.019). In the case of other criteria, PVB and TEA groups were not statistically significantly different. In the study conducted by Okajima et al., no statistically significant difference in respect of the general patient’s satisfaction with treatment (authors used another scale than the one used in our study) was observed between PVB and TEA group (p = 0.26) [11].