Assessment of Pain Control using Ultrasound-guided Bilateral Pecto-intercostal Fascial Plane Block in Pediatric Cardiac Surgeries on Cardiopulmonary Bypass

INTRODUCTION

Cardiac operations are usually considered as moderate-to-high risk surgeries, where maintaining hemodynamic stability in the intraoperative and post-operative period takes precedence over assessment and pain management practices. Untreated pain can have both short and long-term physiological and psychological adverse effects.^[1] Opioids form the mainstay of drugs for the control of post-operative pain in cardiac surgeries, which can delay extubation due to its pharmacological side effects.^[2-4] Patients with cyanotic congenital heart diseases have decreased coagulation factors along with qualitative and quantitative defects in platelet function. Administration of heparin in these coagulopathic pediatric patients, compounded by the effects of cardiopulmonary bypass (CPB), can increase the potential of catastrophic, though rare, risk of epidural hematoma, rendering the use of epidural analgesia more controversial in cyanotic patients. Paravertebral block (PVB) requires it to be placed bilaterally for sternotomy, with the application of the same considerations of anticoagulation as for epidural placement, considering its proximity to the spinal cord.^[5,6] The use of erector spinae plane block (ESPB),^[7] parasternal intercostal block (PICB), and transversus thoracis muscle plane block (TTMPB) has been reported in pediatric patients. Pecto-intercostal fascial block (PIFB) is a relatively novel regional analgesia technique for midline chest incision and sternotomy and can be effectively used in pediatric patients for post-operative analgesia.^[8] It can also decrease the incidence of chronic and persistent pain and improve patient outcomes.^[1] PIFB has been successfully used in acyanotic children undergoing heart surgeries to decrease post-operative pain and opioid requirement.^[9,10] This study was conceptualized to test the safety and efficacy of PIFB in both acyanotic and cyanotic pediatric cardiac surgical patients operated on CPB.

MATERIAL AND METHODS

The study was carried out from January 2023 to January 2024 after obtaining approval from the institutional ethics committee, in accordance with ethical standards and the Helsinki Declaration. Parents/guardians of all enrolled patients were provided with a detailed explanation of the study protocol, and written informed consent was secured. This was a prospective, randomized, single-blinded comparative study involving 90 pediatric patients aged between 1 and 8 years, both acyanotic and cyanotic heart disease patients belonging to the Risk Stratification for Congenital Heart Surgery 2 (RACHS 2) score 1 and 2, undergoing elective cardiac surgery through midline sternotomy on CPB. Exclusion criteria included known allergic reactions to amide-type local anesthetics, pre-operative left ventricular ejection fraction <35%, pre-operative intubation and mechanical ventilation, pre-operative inotropic support, low cardiac output state, ventricular dysrhythmias, emergency surgery, renal failure, stroke, liver failure, and infection at skin puncture areas. Children with intubation duration longer than 8 h or who required re-exploration and re-intubation within 12 h of extubation were also excluded at the follow-up stage. Our study is in accordance with the consolidated standards of reporting trials (CONSORT). Randomization of patients into two groups was performed based on a computer-generated random number sequence. Group P consisted of patients given PIFB with 0.2% ropivacaine mixed with dexamethasone 0.16 mg/kg and Group C (control group) received usual care without any local infiltration.

All patients were preoperatively evaluated according to the institutional protocol. Premedication with syrup promethazine 0.5 mg/kg was given orally, 30 minutes before shifting to the operation theater. The Standard American Society of Anesthesiologists monitoring was applied and anesthesia was induced using sevoflurane in oxygen. Following peripheral intravenous (IV) cannula insertion, midazolam 0.02–0.05 mg/kg, fentanyl 2–3 µg/kg, ketamine 2 mg/kg, and rocuronium 1 mg/kg were administered for tracheal intubation. Femoral arterial catheterization was performed to enable continuous blood pressure monitoring. Central venous access was obtained through the right internal jugular or femoral vein to monitor central venous pressure and facilitate administration of inotropic drugs and fluids. Sevoflurane (1–2%) in an oxygen-air blend was used to maintain anesthesia, supplemented by intermittent boluses of fentanyl (0.5–1 µg/kg) and a continuous infusion of cisatracurium at 0.1 mg/kg/h. After surgical correction, patients were weaned off from CPB with appropriate inotropic support. On achieving hemostasis, sternal and skin closure were done. Hemodynamic stability on minimal inotropic support (≤2 inotropes/vasopressors) and a relatively dry surgical field was ensured before performance of PIFB in Group P.

Ultrasound-guided PIFB

The PIFB was performed with the patient in the supine position under strict aseptic conditions. A high-frequency linear ultrasound transducer (L4–15; Esaote, Genova, Italy) was placed longitudinally approximately 2 cm lateral to the sternal edge in the parasternal region [Figure 1]. After identifying the pectoralis major and internal intercostal muscles, a 5 cm, 22-gauge Stimuplex A block needle (B. Braun, Melsungen, Germany) was advanced using an in-plane, cephalocaudal approach to the fascial plane between these muscles. After confirmation of attainment of the correct plane by injecting 1-2 ml normal saline, indicated by linear spread lifting the pectoralis major muscle, 0.2% ropivacaine + dexamethasone 0.16 mg/kg was injected at the 3^rd and 5^th intercostal space (ICS) after negative aspiration of blood. The entire process was repeated on the contralateral side in a similar ICS, leading to a total dose administration of 3 mg/kg.

Close

Figure 1:

Ultrasound-guided PIFB performance. (a) Sonoanatomy of PIFB with in-plane method, pectoralis major muscle is seen above the rounded anechoic rib shadows; below the pectoralis major is the internal intercostal muscle. Pleura was identified as a bright hyper-echoic line below the intercostal muscle. (b) Needle is visualized in the plane between pectoralis major and internal intercostal muscle. The pectoralis major muscle has been lifted up by the administered drug. (c) Distribution of the drug between the fascial plane spreading both cranial and caudal to the injection point. (d) Position of probe in the in-plane approach, 2 cm lateral to the sternal border with the needle being inserted in a craniocaudal direction. PIFB: Pecto-intercostal fascial plane block, PMM: Pectoralis major muscle, IIM: Internal intercostal muscle, PL: Pleura.

Export to PPT

RESULTS

Ninety-six children were initially screened. Six children did not meet inclusion criteria at enrollment, and seven were subsequently lost to follow-up (re-exploration for bleeding in three patients, re-intubation within 12 h of extubation in two patients due to respiratory distress, prolonged intubation (>8 h) due to hemodynamic instability requiring additional inotropic and vasopressor use, and mechanical ventilation in two patients), therefore finally, 83 patients were included in the study. Participant enrollment, allocation, and follow-up are illustrated in the CONSORT flow diagram [Figure 2].

Close

Figure 2:

Consolidated standards of reporting trials flow diagram showing recruitment process.

Export to PPT

The groups P and C were comparable with regard to demographic data, intraoperative variables, and surgical data [Table 1]. There was no significant difference in age, gender, height, weight, body surface area, RACHS score, CPB duration, and intraoperative fentanyl use between the groups. The procedures included were atrial septal defect, ventricular septal defect (VSD), VSD with pulmonary stenosis for septal defect closure and pulmonary valvotomy/infundibular resection, partial atrio-ventricular canal defect, partial anomalous pulmonary venous connection, intra-cardiac repair for tetralogy of Fallot, bi-directional Glenn surgery, and completion Fontan surgery for single ventricular physiology lesions – tricuspid atresia, double inlet left ventricle, and d-transposition of great arteries with non-routable VSD.

The primary end point of MOPS [Figure 3] after extubation at all-time intervals for 36 h was comparatively less in the PIFB group (P < 0.01). The pain score was lowest at 1 h after extubation in the PIFB group. The average mean pain score was 2.5 in Group P compared to 3.95 in control group. The post-operative fentanyl requirement before extubation was significantly less (P < 0.001) in the Group P (1.09 ± 0.3) as compared to control (2.08 ± 0.54). The time to extubation (hours) was less in the P group (4.75 ± 1.41) in comparison to control group (5.38 ± 1.39). Time to first rescue analgesia after extubation was significantly delayed in the P group (P < 0.001). Post-operative paracetamol and tramadol use was statistically more in the control group (P < 0.001). ICU length of stay and hospital length of stay were statistically less in the P group. There were no adverse events related to the performance of PIFB. Secondary outcomes are summarized in Table 2.

Close

Figure 3:

MOPS trends in PIFB and control group up to 36 h post-extubation. MOPS: Modified objective pain score, PIFB: Pectointercostal fascial plane block.

Export to PPT

DISCUSSION

Early post-operative pain after cardiac surgical procedures peaks within the 1^st 24 h.^[12] Pain in pediatric patients could lead to several untoward consequences such as hypertension, tachyarrhythmias, pulmonary hypertensive crisis, prolonged immobilization, chest wall splinting, decreased respiratory efforts, and could increase length of stay in ICU and hospital. Pain is usually managed with opioids and non-steroidal anti-inflammatory drugs in pediatric patients as in adults note-withstanding, its hemodynamic stability, and reliable postoperative analgesia.^[13] Opioids have side effects, especially respiratory depression, sedation, and drowsiness which could delay extubation.^[14,15] Its effect on the gastrointestinal tract, such as nausea, vomiting, and ileus, can delay resumption of oral feeding after extubation affecting effective application of ERAS protocols in pediatric patients.^[16]

The sternum is supplied by anterior branches of the intercostal nerve (T2-6).^[17] PICB, TTMPB, and PIFB effectively block the anterior intercostal nerve.^[18,19] The disadvantage of the PICB is the requirement of multilevel punctures.^[20] The transversus thoracis muscle (TTM), being very thin, especially in pediatric patients, is difficult to discern from the intercostal muscle.^[21] In addition to its being in close proximity to the pleura, the internal mammary vessels lie above the TTM, increasing the chances of inadvertent pleural and vascular puncture leading to pneumothorax and hematoma if needle is not well visualized, leaving us with a small margin of error.^[22] PIFB, first described by de Ia Torre in 2014, is technically less challenging with analgesic efficacy similar to TTMPB.^[19] The performance of block does not require lateral positioning as for PVB or ESPB which becomes tedious after surgery with drains in situ. In a recent consensus effort to standardize the nomenclature of the chest wall blocks, PIFB is categorized as superficial parasternal intercostal plane blocks.^[23]

Studies on PIFB have been mainly reported in adults, with a handful in pediatric patients. There is no randomized controlled study published to date mentioning the use of PIFB in cyanotic cardiac surgical patients using CPB. Acute postoperative pain was well controlled in the block group for 36 h in our study. As described previously, maximum pain after cardiac surgery occurs in the initial 24 h, decreasing through the 1^st week in the majority of patients. This is in accordance with our study findings, where pain score was noted to increase during the 24 h in both groups. The intraoperative fentanyl dose was similar in both groups, excluding its bias on time to extubation. Post-operative fentanyl requirement was less in Group P, which could be partly indicative of effective pain control and facilitated early extubation. Zhang et al., in their study on 110 pediatric cardiac surgical patients, the pain score measured by MOPS was significantly higher in the saline group compared to the PIFB group at 24 h post-extubation at both rest and on coughing.^[9] Block in their study was given pre-procedure, with observations of reduced intraoperative and post-operative fentanyl use, reduction in time to extubate, ICU, and hospital length of stay. The findings are concurrent with our results, except for reduced intraoperative fentanyl use as the block was given before surgery. Ahmed et al., in their study on 80 pediatric patients given PIFB after induction compared with control group, found lower pain scores for 24 h post-extubation in the block group with concomitant increased intraoperative and post-operative fentanyl requirement in the control group.^[10] These observations are in similar lines to our study, with lower pain score and lower fentanyl requirement in post-operative period. In a study of 50 adults with coronary artery bypass grafting and valve replacement surgery, Wang et al, found low pain score at 12 h while coughing (1.45 ± 1.43 vs. 3 ± 1.71) and at rest in patients given PIFB before surgery, but they did not significantly differ at 24 and 48 h between the two groups, with statistically significant decrease in sufentanil consumption during surgery in the intervention group.^[24] Zhang et al., in their study on 116 adult cardiac surgical patients given continuous PIFB by catheter insertion preoperatively had lower resting and dynamic pain scores at all times for 72 h a post-extubation analyzed in comparison to the controls given saline infusion.^[25] Kumar et al. studied the impact of PIFB in 40 adult cardiac surgeries, the numeric rating scale score being lower till 12 h at both rest and cough in the patients given block, which resembles with our study findings.^[26] Thus, these studies reiterate the effective mitigation of acute post-operative pain by PIFB.

The application of block post-procedure was hypothesized to be more beneficial. No untoward events were seen in our study such as allergy to ropivacaine, bleeding from needle insertion site, vascular puncture, hematoma, or iatrogenic pneumothorax. Since our study population included cyanotic patients which have some probability of post-operative bleeding, it provided us time to assure the attainment of hemodynamic stability and relatively dry surgical field before sternal closure for performance of block, mitigating the participants which could be lost to follow-up due to exclusion. Furthermore, the effective duration of ropivacaine in providing analgesia could be prolonged by post-operative use compared to pre-procedural administration. The use of dexamethasone may also have contributed to increasing the efficacy of pain control.^[20] Pre-procedural use of PIFB has been shown to decrease time to extubation in both pediatric and adult cardiac surgical patients. Future directions in the use of PIFB could be insertion of a catheter bilaterally before commencement of surgery to reduce intraoperative opioid requirement, early extubation, and supplementation of ropivacaine for 3 days in pediatric patients in similar lines to adult patients.^[25,27]

CONCLUSION

Ultrasound-guided bilateral PIFB reliably alleviates acute post-operative pain, is relatively easy to perform, and is safe in pediatric patients undergoing cardiac surgery. This study promotes the application of PIFB in cyanotic children for pain control. Thus, the use of PIFB in cardiac surgical patients could pave the way for an opioid-restrictive cardiac surgery practice and give an impetus to the implementation of ERAS in the pediatric cardiac surgical population.