Comparison of Ultrasound-Guided Thoracic Paravertebral Block Using Ropivacaine and Balanced General Anesthesia in Breast Surgeries.

BACKGROUND AND AIMS: Despite the latest advances in breast surgery, the procedure is frequently associated with postoperative pain, nausea, and vomiting, which leads not only to increased patient's suffering but also to a prolongation of hospital stays and related costs. Thoracic paravertebral block (TPVB) has been successfully used to provide analgesia for multiple thoracic and abdominal procedures in both children and adults.
METHODS: Forty patients were allocated for this observational, comparative study and divided into two groups of 20 each, namely thoracic paravertebral group (Group P) study group and general anesthesia (GA) group (Group G), control group, and observations made for duration of procedure, visual analog score, rescue analgesia, surgeon and patient's satisfaction, postoperative complications, and duration of postanesthesia care unit (PACU) stay in both the groups.
RESULTS: We found that there was a statistically significant difference in duration of procedure, more time was taken in performing TPVB. Pain was better controlled in Group P and requirement of rescue analgesia was higher in Group G patients, postoperative complications such as shivering, nausea, vomiting, and duration of PACU stay were more in patients receiving GA.
CONCLUSION: Hence, we conclude that ultrasound-guided TPVB appears to be safe, reliable, and effective technique for breast surgeries with several advantages over GA in terms of long-lasting pain relief, fewer complications, and shorter hospital stay. Copyright:

INTRODUCTION

Breast surgeries are usually performed under general anesthesia (GA) which has its own disadvantages and known to be associated with postoperative pain, nausea, and vomiting which can negatively affect the postoperative experience and prolong the length of hospital stay.[1] Alternatives of GA for breast surgeries are thoracic paravertebral block (TPVB), pectoral nerve block II, erector spine plane block, and thoracic epidural. TPVB was performed by insinuation of local anesthetics over the spinal nerve roots, which came out from the spinal cord to produce unilateral segmental analgesia and has recently used in breast surgeries for anesthesia purpose.[2] Base of thoracic paravertebral space (TPVS) is formed by vertebral body and anterolaterally space is bounded by parietal pleura, transverse process, and superior castotransverse ligament form its posterior boundary.[3] The sympathetic chain lies in the same facial plane just anterior to the intercostal nerve and communicates with it via the rami communicates. Hence, TPVB produces unilateral sensory, motor, and sympathetic blockade.[4] Placement of local anesthetics within the paravertebral space where the spinal nerves emerge from intervertebral foramina produces unilateral somatic and sympathetic block, which is advantageous for unilateral surgical procedures of the chest and abdomen.[5] TPVB produces unilateral segmental blockage resulting in less hemodynamic alteration as compared with epidural anesthesia.[6] TPVB appears very promising due to reduction in postoperative pain, decreased analgesic consumption with a reduction in postoperative nausea vomiting, less drowsiness, and decreased risk of respiratory depression.[27] There is also a decrease in the incidence of chronic postsurgical pain and improvement in wound healing.[8] Ultrasound guidance can be used to identify the TPVS and needle placement and to monitor the spread of the local anesthetic. It can also help in identification of closely related osseous and neuroaxial structures, thus aiding in preventing their injury.[9] There were only a few studies done with the drug ropivacaine, so it is taken in this study considering its better pharmacological profile in comparison to drug bupivacaine, as studied in various studies.

The present study was conducted with aims of comparative evaluation of perioperative analgesia, anesthesia, and intraoperative hemodynamic changes in Ultrasound guided- thoracic paravertebral block (TPVB)-guided TPVB using ropivacaine versus balanced GA in breast surgeries. In addition, requirement of postoperative rescue analgesia and surgeon as well as patients satisfaction with procedures was also compared.

METHODS

Our study was a comparative observational type conducted at the tertiary care medical institute of Lucknow, India, from March 2019 to August 2020. Our clinical research was standardized following ethical principles of medical research involving human subjects according to the Helsinki Declaration 2013. After obtaining institutional ethical clearance (IEC No 75/17/RMLIMS/2018) and written consent from participants, 40 patients were allocated for this study and divided into two groups of 20 each, namely thoracic paravertebral group (Group P) and GA Group (Group G). About 18–65 years aged female patients undergoing breast surgeries, belong to the American Society of Anesthesiologists (ASA) physical Status I and II, whose axillary lymph nodes are negative on the basis of histopathology are included in the present study. Patients with preexisting respiratory disease, coexisting cardiovascular diseases, obesity (body mass index [BMI] >35 kg/m2), skin infection at the parathoracic block injection site, bleeding diathesis, coagulopathy, platelet count <100,000/mm3, and severe anatomic abnormality of the spine and patients having a history of known allergy with ropivacaine and having psychiatric disorder are exempted from this study. All eligible patients were assessed thoroughly in preanesthetic checkup (PAC) then PAC fit patients were posted for surgery.

Tablet alprazolam 0.25 mg, tablet ranitidine 150 mg, and tablet metoclopramide 10 mg were administered the night before surgery to the patients in both the groups. On arrival in the operation theater, electrocardiogram, pulse oximetry, and noninvasive blood pressure monitoring was done and baseline readings of pulse rate and blood pressure were taken. Then, an 18 G intravenous cannula was secured and ringer lactate solution was infused at appropriate rate before starting anesthetic procedure.

For the TPVB group (Group P), after the aseptic precautions, patients were kept in sitting or lateral decubitus position. A linear transducer probe was used and scanning process was started 5–10 cm lateral to the midline to identify the rounded ribs and parietal pleura underneath. The transducer was then moved progressively more medially until transverse processes were identified. Eighteen G Tuohy's needle was inserted out of plane to contact the transverse process and then walked off the transverse process. Insertion was limited to <1.5 cm past the transverse process and after finding the loss of resistance to the injected air which confirms the tip of the needle in the paravertebral space, followed by negative aspiration to exclude accidental blood vessel puncture. A 20 G epidural catheter was placed and local anesthetic solution of 0.5% ropivacaine in a dose of 15 ml was injected slowly over 2–3 min. Injection of the local anesthetic resulted in displacement of the parietal pleura. After confirmation of analgesia from the lower border of the clavicle to the inferior costal margin, the surgery was started. Supplemental oxygen at 5 l/min was administered via face mask. Patients were sedated with midazolam 1–2 mg i. v. and supplementary doses were given whenever required. In the event of failure of thoracic paravertebral anesthesia, GA was administered. Postoperatively, 10 ml of 0.2% ropivacaine was used through a catheter placed in the paravertebral space and diclofenac 75 mg i. v. was given as rescue analgesia whenever visual analog score (VAS) was >3.

All patients in the GA group (Group G) were premedicated with midazolam 1.5–2 mg i. v. and fentanyl 2 μg.kg−1 i. v. Simultaneously, they were preoxygenated with 100% O2 for 3 min. Patients were induced with propofol 2 mg.kg−1 i. v. and tracheal intubation under direct laryngoscopy was facilitated by vecuronium 0.1 mg.kg−1 intravenously. Anesthesia was maintained by isoflurane in combination with air and O2. Vecuronium 0.01 mg.kg−1 i. v. and fentanyl 25 μg i. v. were given intermittently whenever required. Intraoperative hypotension and hypertension were considered as ±20% from the baseline blood pressure level. Similarly, bradycardia and tachycardia were considered ±20% from the baseline heart rate (HR) readings. Hypotension was treated with phenylephrine 25–50 μg as i. v. bolus and bradycardia was treated with 0.3–0.6 mg i. v. atropine. In the end, patients were reversed with neostigmine at 50–80 μg.kg−1 i. v. and glycopyrrolate at 10 μg.kg−1i. v. Paracetamol 1 g i. v. was given before extubation. The patients were extubated following return of regular, rhythmic respiration when reasonably awake. Postoperative diclofenac 75 mg i. v. was given as a rescue analgesia whenever VAS score was >3. Intraoperatively, the hemodynamic parameters were recorded and length of surgery was noted. The surgeon was asked to evaluate the operating conditions as satisfied or not satisfied. Length of stay in the postoperative recovery room was also noted. Quality of postoperative analgesia was noted by VAS scale every 1 h till the first dose of rescue analgesia was given. In the both “P” and “G” group cutoff value of VAS score for rescue analgesia was kept at >3. VAS score is in the range of 0–10 where a score 0 signifies no pain, whereas a score 10 signifies the worst pain experienced ever. Incidences of other side effects such as shivering, nausea, and vomiting were noted. At the time of discharge from the recovery room, patients were asked to rate their satisfaction with the anesthetic technique as satisfied or not satisfied.

Statistical analysis

Sample size calculation

Our experience in past with similar patients showed that in a period of 18 months (equal to the length of proposed study), approximately 200 patients were operated using GA and 40 patients were operated using TPVB. The sampling intervals calculated for GA and TPVB were 10 and 2, respectively. The first patient in each group was selected randomly and subsequent enrolments were based on the sampling intervals respectively. The sample size of 20 in each group was calculated on basis of a previous study in which the VAS scores for both these groups were normally distributed with a standard deviation (SD) of approximately 1. If the true difference in the mean VAS score measured in TPVB group and GA group measured at 120 min following the end of the surgery is 1, we needed to study 17 subjects in each group to be able to reject the null hypothesis that the mean VAS scores in both these group are equal with probability (power) of 0.8 (80%). The type 1 error probability associated with this null hypothesis is 0.05. Assuming that there would be loss of 20% of patients owing to inclusion and exclusion criteria by varied reasons such as death, coma, and negative consent, we enrolled 20 cases in each group.

The results were presented in frequencies, percentages, and mean ± SD; the Chi-square test or Fisher's exact test was used to compare categorical variables between the groups. The Student unpaired t-test was used to compare continuous variables between the groups. P < 0.05 was considered significant. All the analyses were carried out using SPSS 16.0 version (Chicago, Inc., USA).

RESULTS

In our study, both the groups were comparable in terms of the demographic variables (age, BMI, and ASA grade) and no statistically significant difference was found (P > 0.05). The results were made in terms of intergroup comparison between study (Group P) and control (Group G). As shown in Table 1, the duration of procedure was significantly (P = 0.03) higher among the study group (1.88 ± 0.73) as compared to the control group (1.39 ± 0.69). Duration of postanesthesia care unit (PACU) stay was lower among the study group (1.50 ± 0.66) than the control group (2.35 ± 0.89) which was statistically significant (P = 0.002) [Table 1]. The initial pulse rate and systolic and diastolic blood pressures (DBPs) were comparable between both the groups and also after anesthesia throughout during the surgery, the difference was statistically insignificant (P > 0.05) [Table 2]. Table 3 shows the comparison of VAS between the groups at the end of treatment and hourly up to 3 h. VAS was significantly (P = 0.001) lower among study than in the control group at the end of treatment, 1st h, and 2nd h. As shown in Graph 1, there was a statistically significant (P < 0.001) difference in postoperative rescue analgesia between the groups at the end of treatment, 1st h, and 2nd h, but the difference was not significant (P > 0.05) in the 3rd h. As shown in Graph 2, postoperative complications such as shivering, nausea, and vomiting were lower among the study group than the control group with a statistically significant difference (P = 0.0001). As depicted in Graph 3, surgeon's satisfaction was among 85% of the study group and 100% of the control group, but this difference was not found statistically significant (P > 0.05). Patient's satisfaction was among 80% of the study group and 85% of the control group which was also statically insignificant (P > 0.05).

Table 1

Comparison of duration of procedure and postanesthesia care unit stay between the groups

Variables	Mean±SD		Pa
	Study	Control
Duration of procedure	1.88±0.73	1.39±0.69	0.03*
PACU stay	1.50±0.66	2.35±0.89	0.002*

aUnpaired t-test, *P<0.05 – statically significant. SD=Standard deviation, PACU=Postanesthesia care unit

Table 2

Comparison of hemodynamic response among patients of both groups

Hemodynamic parameters	Groups	Time (min); mean±SD
		0	5	10	15	30	60	90	120
Heart rate	Study	88.26±18.14	82.25±14.76	81.05±14.67	80.65±14.46	80.20±12.84	78.35±77.18	78.31±16.04	81.30±14.61
	Control	84.05±21.81	82.10±16.14	80.50±13.23	80.40±13.33	78.45±14.63	77.18±18.46	79.80±17.86	79.83±13.21
Systolic blood pressure	Study	130.70±15.09	122.45±15.46	118.25±17.37	119.50±11.02	120.00±14.63	117.55±12.90	118.12±11.82	114.00±11.16
	Control	124.45±18.10	113.40±22.08	115.95±19.41	120.40±20.18	121.00±19.39	117.41±17.11	112.50±13.67	112.17±0.80
Diastolic blood pressure	Study	78.80±9.46	74.30±10.52	74.45±11.30	75.40±7.21	76.256±8.37	74.95±10.33	75.75±7.07	72.40±10.11
	Control	79.95±11.87	73.60±11.74	76.40±13.45	75.90±14.18	81.55±13.61	77.65±11.35	80.50±12.11	73.50±10.27

Unpaired t-test, P<0.05 – statically significant. SD: Standard deviation

Table 3

Comparison of visual analog score between the groups across the time periods

Groups	Mean±SD		Pa
	Study (n=20)	Controls (n=20)
End of treatment	3.05±1.35	7.70±1.12	0.001*
1st h	2.30±1.08	7.10±1.37	0.001*
2nd h	1.70±0.86	6.47±1.26	0.001*
3rd h	3.75±1.70	3.50±0.70	0.85

Unpaired t-test, *P<0.05 – statically significant. SD: Standard deviation

Graph 1

Comparison of postoperative rescue analgesia between the groups

Graph 2

Comparison of complications between the groups

Graph 3

Comparison of surgeon and patient's satisfaction between the groups

DISCUSSION

The present study was carried out with the objective to compare hemodynamic parameters and perioperative analgesia and anesthesia in patients posted for breast surgeries under USG-guided thoracic paravertebral block versus balanced GA. Both the groups were comparable in terms of demographic variables. There was no statistically significant (P > 0.05) difference in hemodynamic parameters (HR, systolic blood pressure, and DBP), between the groups at all the time periods. We did not encounter any episode of hypotension in Group P because only unilateral somatosensory and sympathetic blockade was produced. It appears that with unilateral blocks, the sympathetic block produced is less intense compared to epidural block and is only unilateral, thus avoiding side effects such as hypotension and bradycardia. Sonil et al.[10] studied that extradural anesthesia selectively blocks unilateral cardiac sympathetic fibers, and this offers potential patient benefits: attenuation of the surgical stress response, improvement of myocardial oxygen balance, and stabilization of intraoperative hemodynamic. Saito et al.[11] also concluded that TPVB provides a reliable, unilateral, somatosensory and sympathetic block without producing hypotension and tachycardia associated with central neuraxial blocks. These findings are in line with the study of Lonnqvist et al.[12] who reported that the incidence of hypotension after paravertebral block is low (4.9%) and this is in marked contrast to epidural block. We also observed in our study that there are no significant alterations in hemodynamics in both the groups. While comparing the VAS between the groups, it was significantly (P = 0.001) lower among Group P than Group G at the end of treatment, 1st h, and 2nd h owing to persistent sensory blockade for a prolonged period. Pusch et al.[13] observed 86 patients posted for breast surgeries divided into single paravertebral block and GA and concluded that postoperative pain scores (VAS) was lower in the paravertebral group. Naja et al.[14] who stated VAS both at rest and at movement, as well as the need for supplemental opioid administration during the first 3 days postoperatively, were significantly lower in patients who had been administered TPVB as compared to patients who received GA. Similarly, the difference in postoperative rescue analgesia between the groups was highly significant (P < 0.001) at the end of treatment and 1st h and significant (P = 0.006) at the 2nd h, while the difference was not significant (P > 0.05) at the 3rd h. There was manyfold increase in supplemental analgesic requirement in GA group in the PACU, compared with that used in the TPVB group in the immediate postoperative period up to 2 h. TPVB efficiently suppresses cortical responses to thoracic dermatomal stimulation which might inhibit a central reflex involved in pain. Kairaluoma et al.[15] found that preincisional TPVB provides significant immediate postoperative analgesia after breast cancer surgery. In addition, preoperative TPVB seems to reduce the prevalence of chronic pain 1 year after breast cancer surgery. Dabbagh and Elyasi.[16] studied in 60 patients scheduled for breast surgeries between GA and paravertebral block and concluded paravertebral block as a suitable alternative to GA in selected breast surgical patients regarding postoperative pain reduction. Duration of stay in PACU was significantly (P = 0.002) lower among Group P (1.50 ± 0.66) than Group G (2.35 ± 0.89) which may be due to pain, nausea, and vomiting experienced by the Group G patients attributable to increased opioid consumption resulted in their longer stay. The decrease in length of hospital stay in Group P was associated with an improved pain control after surgery and a reduction in intraoperative and postoperative narcotics use, with a consequential decrease in postoperative nausea and vomiting. Coveney et al.[17] performed paravertebral block in 100 patients posted for breast surgeries and found that this technique allows early ambulation and reduces the duration of intensive care unit stay. Eswaran[18] stated that the use of TPVB was also associated with a significantly shorter hospital stay (median 1 day) compared to GA (2 days). Coopey et al.[19] used perioperative paravertebral block in patients of mastectomy and found that hospital stay was significantly decreased. Complications such as shivering and nausea between the groups were compared and found to be lower among the Group P than Group G with very statistically significant (P = 0.0001) difference. Higher complications in Group G could be the consequence of GA, higher opioid consumption, and postoperative pain. Coveney et al.[17] performed paravertebral block in 100 patients posted for breast surgeries and found that the incidence of nausea, vomiting, and surgical pain was less in patients receiving paravertebral block. Greengrass et al.[20] studied in 25 patients undergoing breast surgeries under paravertebral block and found a minimal incidence of nausea, vomiting, and postoperative pain in comparison to GA. Ravinder Kumar Batra et al. (2011)[2] reviewed that postoperative nausea and vomiting are significantly lower in patients given TPVB compared to GA. Although surgeon's satisfaction was slightly less with TPVB group, it was not significant (P = 0.55) and may be due to the longer duration of surgery due to time taken for arranging the modalities before actual start of surgery and not achieving the proper muscle relaxation in some cases. Similarly, the lower patient's satisfaction in the TPVB group, although insignificant (P = 0.67), may be due to patient's anxiety and little bit of uncooperative behavior of patients in the beginning due to apprehension of being awake and being aware of the surgical procedure, though we were able to relax the patients with consolation and anxiolysis. Weltz et al.[21] performed paravertebral block in 15 patients posted for breast cancer surgeries and found that postoperative pain was effectively controlled. Nausea and vomiting afflicted in lower patients. Ninety-three percent of their patients rated the experience as very satisfactory. Greengrass et al.[20] studied 25 patients undergoing breast surgeries under paravertebral block and found in their study that patients with successful blocks were all very satisfied. Similarly, Eswaran et al.(2017)[18] also concluded in her study that patient satisfaction has also been high with TPVB technique making it the most meaningful aspect of using TPVB. However, the duration of procedure was significantly (P = 0.03) higher among patients of Group P (1.88 ± 0.73) in comparison to patients of Group G (1.39 ± 0.69). This may be due to more time taken by ropivacaine to achieve sensory/motor block (approximately 5 min for sensory block and approximately 15 min for motor block), extra part preparation, use of USG and its mobilization, support staff unfamiliarity with the procedure, and time consumed in performing the procedure. Despite the additional time required on behalf of the anesthesiologist, the technique offers potential postoperative benefits that may justify the increased effort. Finally, the results from this initial pilot study are promising and suggest that TPVB may be a useful tool to improve pain control in patients undergoing surgery for breast cancer. These preliminary findings provide a platform for future so that more extensive evaluation of USG-guided TPVB procedure can be done in a routine manner for both patient's and surgeon's benefit.

CONCLUSION

Hence, we conclude that ultrasound-guided TPVB appears to be safe, reliable, and effective technique for breast surgeries with several advantages over GA in terms of long-lasting pain relief, fewer complications, and shorter hospital stay. Since the proposed study is a pilot study, sample size estimation has not been done and the study may be underpowered to access the difference in pain sensation of the two groups.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.