Intercostal nerve cryoablation versus thoracic epidural catheters for postoperative analgesia following pectus excavatum repair: Preliminary outcomes in twenty-six cryoablation patients

Cryoanalgesia: Review with Respect to Peripheral Nerve

BACKGROUND

 Cryoanalgesia is a tool being used by interventional radiology to treat chronic pain. Within a certain cold temperature range, peripheral nerve function is interrupted and recovers, without neuroma formation. Cryoanalgesia has most often been applied to the intercostal nerve. Cryoanalgesia has applications to peripheral nerve surgery, yet is poorly understood by reconstructive microsurgeons.

METHODS

 Histopathology of nerve injury was reviewed to understand cold applied to peripheral nerve. Literature review was performed utilizing the PubMed and MEDLINE databases to identify comparative studies of the efficacy of intraoperative cryoanalgesia versus thoracic epidural anesthesia following thoracotomy. Data were analyzed using Fisher's exact and analysis of variance tests. A similar approach was used for pudendal cryoanalgesia.

RESULTS

 Application of inclusion and exclusion criteria resulted in 16 comparative clinical studies of intercostal nerve for this review. For thoracotomy, nine studies compared cryoanalgesia with pharmaceutical analgesia, with seven demonstrating significant reduction in postoperative opioid use or postoperative acute pain scores. In these nine studies, there was no association between the number of nerves treated and the reduction in acute postoperative pain. One study compared cryoanalgesia with local anesthetic and demonstrated a significant reduction in acute pain with cryoanalgesia. Three studies compared cryoanalgesia with epidural analgesia and demonstrated no significant difference in postoperative pain or postoperative opioid use. Interventional radiology targets pudendal nerves using computed tomography imaging with positive outcomes for the patient with pain of pudendal nerve origin.

CONCLUSION

 Cryoanalgesia is a term used for the treatment of peripheral nerve problems that would benefit from a proverbial reset of peripheral nerve function. It does not ablate the nerve. Intraoperative cryoanalgesia to intercostal nerves is a safe and effective means of postoperative analgesia following thoracotomy. For pudendal nerve injury, where an intrapelvic surgical approach may be difficult, cryoanalgesia may provide sufficient clinical relief, thereby preserving pudendal nerve function.

Cryoanalgesia as the Essential Element of Enhanced Recovery after Surgery (ERAS) in Children Undergoing Thoracic Surgery-Scoping Review

This article aims to present cryoanalgesia as an inventive strategy for pain alleviation among pediatric patients. It underlines the tremendous need to align pain management with the principles of the enhanced recovery after surgery (ERAS) approach. The aim of the study was to review the patient outcomes of nerve cryoanalgesia during surgery reported with regard to ERAS in the literature. The literature search was performed using PubMed and Embase to identify articles on the use of cryoanalgesia in children. It excluded editorials, reviews, meta-analyses, and non-English articles. The analysis focused on the study methods, data analysis, patient selection, and patient follow-up. This review includes a total of 25 articles. Three of the articles report the results of cryoanalgesia implemented in ERAS protocol in children. The research outcome indicates shortened hospital stay, potential reduction in opioid dosage, and significant progress in physical rehabilitation. This paper also describes the first intraoperative utilization of intercostal nerve cryoanalgesia during the Nuss procedure in Poland, highlighting its effectiveness in pain management. Adding the cryoanalgesia procedure to multimodal analgesia protocol may facilitate the implementation of the ERAS protocol in pediatric patients.

Intercostal Nerve Cryoablation Reduces Opioid Use and Length of Stay Without Increasing Adverse Events: A Retrospective Cohort Study of 5442 Patients Undergoing Surgical Correction of Pectus Excavatum

OBJECTIVE

To examine differences in opioid use, length of stay, and adverse events after minimally invasive correction of pectus excavatum (MIRPE) with and without intercostal nerve cryoablation.

BACKGROUND

Small studies show that intraoperative intercostal nerve cryoablation provides effective analgesia with no large-scale evaluations of this technique.

METHODS

The pediatric health information system database was used to perform a retrospective cohort study comparing patients undergoing MIRPE at children's hospitals before and after the initiation of cryoablation. The association of cryoablation use with inpatient opioid use was determined using quantile regression with robust standard errors. Difference in risk-adjusted length of stay between the cohorts was estimated using negative binomial regression. Odds of adverse events between the two cohorts were compared using logistic regression with a generalized estimating equation.

RESULTS

A total of 5442 patients underwent MIRPE at 44 children's hospitals between 2016 and 2022 with 1592 patients treated after cryoablation was introduced at their hospital. Cryoablation use was associated with a median decrease of 80.8 (95% CI: 68.6-93.0) total oral morphine equivalents as well as a decrease in estimated median length of stay from 3.5 [3.2-3.9] days to 2.5 [2.2-2.9] days ( P value: 0.016). Cryoablation use was not significantly associated with an increase in any studied adverse events.

CONCLUSIONS

Introduction of cryoablation for perioperative analgesia was associated with decreased inpatient opioid use and length of stay in a large sample with no change in adverse events. This novel modality for perioperative analgesia offers a promising alternative to traditional pain management in thoracic surgery.

Cryoablation Reduces Opioid Consumption and Length of Stay After Pulmonary Metastasectomy

INTRODUCTION

Intraoperative cryoablation of intercostal thoracic nerves is gaining popularity as a technique that decreases postoperative pain in thoracic surgery. Our study evaluates the efficacy and safety of cryoablation in pain management of pediatric cancer patients undergoing thoracotomy.

METHODS

We reviewed cancer patients undergoing thoracotomies for pulmonary metastasis resection at our children's hospital from 2017 to 2023. Patients who received cryoablation were compared to those who did not. Our primary outcomes were self-reported postoperative pain scores (from 0 to 10) and opioid consumption, measured as oral morphine equivalent per kilogram.

RESULTS

Thirty eight procedures were performed in 17 patients, of which 11 (64.7%) were males. Cryoablation was used in 14 (32.4%) procedures, while it was not in 24 (67.6%). Median age (17 y in both groups, P = 0.84) and length of surgery (300 cryoablation versus 282 no cryoablation, P = 0.65) were similar between the groups. Patients treated with cryoablation had a shorter hospital stay compared to those who did not (3.0 versus 4.5 d, respectively, P = 0.04) and received a lower total dose of opioids (2.2 oral morphine equivalent per kilogram versus 14.4, P = 0.004). No significant difference was noted in daily pain scores between the two groups (3.8 cryoablation versus 3.9 no cryoablation, P = 0.93). There was no difference in rates of readmissions between the cryoablation and no-cryoablation groups (14.3% versus 8.3%, P = 0.55).

CONCLUSIONS

Our study suggests that cryoablation of the thoracic nerves during a thoracotomy is associated with reduced opiate consumption and shorter hospital stay. Cryoablation appears to be a promising technique for pain management in this patient population.

Long-Term Sensory Function 3 years after Minimally Invasive Repair of Pectus Excavatum with Cryoablation

INTRODUCTION

Minimally invasive repair of pectus excavatum (MIRPE) with intercostal nerve cryoablation (Cryo) decreases length of hospitalization and opioid use, but long-term recovery of sensation has been poorly described. The purpose of this study was to quantify long-term hypoesthesia and neuropathic pain after MIRPE with Cryo.

METHODS

A prospective cohort study was conducted single-institution of patients ≤21 years who presented for bar removal. Consented patients underwent chest wall sensory testing and completed neuropathic pain screening. Chest wall hypoesthesia to cold, soft touch, and pinprick were measured as the percent of the treated anterior chest wall surface area (TACWSA); neuropathic pain was evaluated by questionnaire.

RESULTS

The study enrolled 47 patients; 87% male; median age 18.4 years. The median bar dwell time was 2.9 years. A median of 2 bars were placed; 80.9% were secured with pericostal sutures. At enrollment, 46.8% of patients had identifiable chest wall hypoesthesia. The mean percentage of TACWSA with hypoesthesia was 4.7 ± 9.3% (cold), 3.9 ± 7.7% (soft touch), and 5.9 ± 11.8% (pinprick). Hypoesthesia to cold was found in 0 dermatomes in 62%, 1 dermatome in 11%, 2 dermatomes in 17% and ≥3 dermatomes in 11%. T5 was the most common dermatome with hypoesthesia. Neuropathic symptoms were identified by 13% of patients; none required treatment.

CONCLUSION

In long-term follow up after MIRPE with Cryo, 46.8% of patients experienced some chest wall hypoesthesia; the average TACWSA with hypoesthesia was 4-6%. Hypoesthesia was mostly limited to 1-2 dermatomes, most commonly T5. Chronic symptomatic neuropathic pain was rare.

LEVEL OF EVIDENCE

Level IV.

Lessons Learned after 176 Patients Treated with a Standardized Procedure of Thoracoscopic Cryoanalgesia during Minimally Invasive Repair of Pectus Excavatum

BACKGROUND

Intrathoracic intercostal cryoanalgesia (Cryo) during minimally invasive repair of pectus excavatum (MIRPE) reports have been related to improved pain management, although its extent differs amongst studies. We aimed to report our experience using a standardized perioperative approach including Cryo during MIRPE, and compare our actual results with those of a previous thoracic epidural analgesia (TE) cohort. Lessons learned are summarized.

METHODS

Retrospective study including patients undergoing Cryo during MIRPE between October 2018 and May 2023. Results with a standardized perioperative approach were analyzed. We then compared our Cryo cohort with a previous cohort of 62 patients who underwent TE and MIRPE between 2013 and 2018. Continuous variables were reported as mean and standard deviation, and as median (interquartile range) for variables with non-uniform distribution.

RESULTS

We performed 176 Cryo during MIRPE (16.8 ± 4.6 years), with a mean postoperative length of stay (LOS) of 1.4 ± 0.8 days and a median total requirement of 7.5 (0.0; 15.0) oral morphine equivalents (OME) (mg). Patients with Cryo had a significantly lower mean LOS (1.4 ± 0.8 vs. 3.6 ± 1.0 days, p < 0.0001), and median total opioid requirement [7.5 (0.0; 15.0) vs. 77.4 (27.0; 115.5 OME (mg), p < 0.0001) compared to TE patients. Lessons learned included ensuring adequate contact of the cryoprobe with the target, proper exposition, and specialized multidisciplinary perioperative patient and family support, including psychology and physical therapy.

CONCLUSIONS

In this study, we reported lessons learned after performing a standardized protocol of perioperative care in patients undergoing Cryo during MIRPE. This protocol enabled the achievement of a short LOS and low postoperative opioid requirement.

TYPE OF STUDY

Retrospective comparative study.

LEVEL OF EVIDENCE

III.

Intercostal Nerve Cryoablation or Epidural Analgesia for Multimodal Pain Management after the Nuss Procedure: A Cohort Study

BACKGROUND

 Nuss procedure for pectus excavatum is a minimally invasive, but painful procedure. Recently, intercostal nerve cryoablation has been introduced as a pain management technique.

MATERIALS AND METHODS

 In this cohort study, we compared the efficacy of multimodal pain management strategies in children undergoing a Nuss procedure. The effectiveness of intercostal nerve cryoablation combined with patient-controlled systemic opioid analgesia (PCA) was compared with continuous epidural analgesia (CEA) combined with PCA. The study was conducted between January 2019 and July 2022. Primary outcome was length of stay (LOS), and secondary outcomes were operation room time, postoperative pain, opioid consumption, and gabapentin use.

RESULTS

 Sixty-six consecutive patients were included, 33 patients in each group. The cryoablation group exhibited lower Numeric Rating Scale (NRS) pain scores on postoperative day 1 and 2 (p = 0.002, p = 0.001) and a shorter LOS (3 vs. 6 days (p < 0.001). Cryoablation resulted in less patients requiring opioids at discharge (30.3 vs. 97.0%; p < 0.001) and 1 week after surgery (6.1 vs. 45.4%; p < 0.001)). In the CEA group, gabapentin use was more prevalent (78.8 vs. 18.2%; p < 0.001) and the operation room time was shorter (119.4 vs. 135.0 minutes; p < .010). No neuropathic pain was reported.

CONCLUSIONS

 Intercostal nerve cryoablation is a superior analgesic method compared with CEA, with reduced LOS, opioid use, and NRS pain scores. The prophylactic use of gabapentin is redundant.

Intercostal spinal nerve cryoablation for analgesia following pectus excavatum repair

Pectus excavatum is a common chest wall deformity, most often treated during adolescence, that presents a significant postoperative pain control challenge for pediatric surgeons following surgical correction. The purpose of this article is to review the technique and outcomes of intercostal spinal nerve cryoablation for postoperative analgesia following surgical correction of pectus excavatum. Contemporary and historic literature were reviewed. Findings are summarized to provide a concise synopsis of the benefits of intercostal spinal nerve cryoablation relative to alternative analgesic modalities, as well as advocate for more widespread inclusion of this technique into multimodal pain regimens.

Serratus anterior plane block for acute pain management after pectus excavatum repair

Introduction

Conventional postoperative pain management using an intravenous (IV) patient-controlled approach or thoracic epidural analgesia is suboptimal following minimally invasive repair of the pectus excavatum (MIRPE). Recently, cryoanalgesia has gained popularity owing to its superior pain control outcomes compared to those associated with conventional methods. However, because of its invasiveness, additional instrumentation requirement, and limited effect at early postoperative periods, we hypothesized that serratus anterior plane block (SAPB) could be an effective method for post-repair pain management and a possibly superior alternative.

Methods

We conducted a retrospective cohort study of pediatric patients who had undergone MIRPE between March 2022 and August 2023. We compared the efficacy of pain control in three groups among 74 patients: Group N (conventional pain management, n = 24), Group C (cryoanalgesia, n = 24), and Group S (SAPB, n = 26). Group N received IV patient-controlled analgesia (PCA) and a subcutaneous local anesthetic infusion. Group C received bilateral cryoanalgesia on the fourth and seventh intercostal nerves using a cryoprobe at -80°C for 2 min during the operation and IV-PCA postoperatively. Group S received continuous bilateral SAPB with 0.25% ropivacaine and IV-PCA. The pain levels were measured using the visual analog scale (VAS; resting and dynamic), and the total IV rescue analgesic consumption was determined.

Results

The three groups had similar baseline characteristics. Group S showed significantly less pain throughout the immediate postoperative course, resting VAS score at 3 h (Group N, 7.21 vs. Group C, 5.75 vs. Group S, 3.81; p < 0.001), and prominent less total IV rescue analgesic consumption (Group N, 116.16 mg vs. Group C, 52.75 mg vs. Group S, 16.61 mg; p < 0.001).

Conclusion

SAPB resulted in better postoperative pain control than that associated with cryoanalgesia and conventional pain management after pectus excavatum repair, As it was effective in the immediate postoperative period, achieving a VAS score of <4 points (moderate pain) at 3 h postoperatively, it may play an important role and replace invasive cryoanalgesia in the management of pain after pectus surgery.

Measurement and Thermodynamic Modeling of Energy Flux During Intercostal Nerve Cryoablation

INTRODUCTION

Intercostal nerve cryoablation is an increasingly adopted technique to decrease postoperative pain in patients undergoing surgical correction of pectus excavatum (SCOPE). Concerns regarding cryo-induced systemic hypothermia have been raised in pediatric patients; however, assessment of a cooled cryoprobe on body temperature has not been performed. We aimed to determine the energy flux from a maximally cooled cryoprobe and model the possible effects on a whole-body system.

METHODS

To directly measure energy flux, a maximally cooled cryoSPHERE probe (AtriCure, Inc, Mason, OH) was isolated in a well-mixed water bath at 37°C. Real-time temperatures were recorded. Three models were created to estimate intraoperative flux. Perioperative temperatures of 50 patients who received cryoablation during SCOPE were compared to 50 patients who did not receive cryoablation.

RESULTS

Direct calorimetry measured average energy flux of the maximally cooled cryoprobe to be 28 J/s. Thermodynamic modeling demonstrated the following: 1) The highest possible cryoprobe flux is less than estimated basal metabolic rate (BMR) of the average teenager undergoing SCOPE and 2) Flux in a best model of human tissue energy transfer using available literature is far less than the effects of BMR and insensible losses. Clinically, there were no significant differences in the minimum intraoperative, end procedure or first postoperative body temperatures for patients who received cryoablation and those who did not.

CONCLUSIONS

Cryoprobe flux is significantly fewer joules per second than BMR. Furthermore, in a clinical series there were no empiric differences in body temperature due to cryoablation employment, contradicting concerns regarding hypothermia secondary to cryoablation.

Intercostal nerve cryoablation reduces opioid utilization after thoracotomy in children with cancer

BACKGROUND

Intercostal nerve cryoablation (INC) has shown promise as an adjunct method for analgesia in adults undergoing thoracotomy, but has yet to be widely used in children for this indication. We hypothesize that INC decreases opioid utilization in children undergoing thoracotomy for cancer operations.

METHODS

A retrospective review was performed of children who underwent thoracotomy for cancer diagnosis at a freestanding children's hospital from 2018 to 2023. Patient characteristics, intraoperative data, and data on clinical course were collected. Patients were divided into those who underwent INC and those who underwent routine care for comparison.

RESULTS

Twenty-six patients underwent 38 procedures at a median age of 16 years (range 5-21 years). INC was performed in 23 cases over a median of five intercostal levels (range 2-7). Total oral morphine equivalents during inpatient admission were significantly lower in INC patients (137.6 vs. 514.5 mg, p = .002). Routine care patients were more likely to be discharged with an opioid prescription (30.4% vs. 80.0%, p = .008). Length of stay was similar between patients with INC and routine care (4 vs. 5 days, p = .15). There were no differences in rates of reoperation or 30-day re-admission (emergency department or inpatient).

CONCLUSTIONS

INC is a feasible and safe adjunct for children undergoing thoracotomy for cancer. INC is associated with reduced postoperative opioid utilization with respect to both inpatient use and outpatient prescriptions.

Intrathoracic plates versus extrathoracic plates: a comparison of postoperative pain in surgical stabilization of rib fracture technique

Background

Surgical stabilization of rib fractures (SSRF) has been shown to improve outcomes, yet there is an absence of studies comparing SSRF techniques. An intrathoracic system that minimizes incision length has recently been developed and adopted by multiple institutions. We hypothesized that SSRF with an intrathoracic system plus intercostal nerve cryoneurolysis (IC) leads to improved pain control compared with an extrathoracic system plus IC.

Methods

A single-center, retrospective chart review was performed comparing intrathoracic SSRF versus extrathoracic SSRF, and included patients undergoing SSRF from 2015 to 2021 at a level 1 trauma center. Patients who did not undergo intercostal nerve cryoablation were excluded. The primary outcome was opioid consumption based on morphine milligram equivalent (MME) consumption. We collected Rib score, Blunt Pulmonary Contusion 18 Score, number of rib fractures, number of ribs plated, and Injury Severity Score (ISS) to compare baseline characteristics of each group.

Results

A total of 112 patients were evaluated for study inclusion. Thirty-one patients were excluded due to missing outcomes data and/or lack of cryoablation. There was no difference in ISS or Rib Score between the intrathoracic (n=33) and extrathoracic (n=48) groups. At 7-day follow-up, the median MME requirement was significantly lower in the intrathoracic group (21.25) versus the extrathoracic group (46.20) (p=0.02).

Conclusion

Intrathoracic SSRF was associated with a lower postoperative MME consumption compared with extrathoracic SSRF. These data support the use of intrathoracic SSRF to improve pain control compared to extrathoracic SSRF.

Level of evidence

III.

Evaluation of Analgesic Practice Changes Following the Nuss Procedure in Pediatric Patients

INTRODUCTION

Pectus excavatum repair by the Nuss procedure results in severe postoperative pain. Regional blocks and intercostal nerve cryoablation (INC) have emerged as potential strategies to manage analgesia. This study compares pain-related outcomes following these perioperative interventions.

METHODS

We reviewed charts of patients <18 y who underwent the Nuss procedure at Duke Children's Hospital from July 2018 to June 2022. Patients were divided into three groups by analgesic strategy: no block, regional catheters, or INC, representing the chronologic change in our practice. The primary outcome was total and daily in-hospital opioid utilization measured by oral morphine equivalents (OMEs). Secondary outcomes included average daily pain scores, length of stay, opioid refills after discharge, and complications.

RESULTS

Twenty-one patients were included and analyzed: no block (n = 6), regional catheters (n = 7), and INC (n = 8). INC-treated patients required significantly lower total postoperative, in-hospital OMEs (64 ± 47 [mean ± standard deviation]) than those with no block (270 ± 217, P = 0.04) or those with regional catheters (273 ± 176, P = 0.03). INC was associated with longer average operative times (161 ± 36 min) than no block (105 ± 21 min, P = 0.005) or regional catheters (90 ± 11 min, P < 0.001). INC-treated patients had shorter hospital length of stays (median 68 h) than those with regional catheters (median 74 h, P = 0.006).

CONCLUSIONS

INC was associated with longer operative times but decreased in-hospital OMEs when compared to bilateral regional block catheters and multimodal analgesia alone.

Association of Intercostal Nerve Cryoablation During Nuss Procedure With Complications and Costs

BACKGROUND

Intercostal nerve cryoablation with the Nuss procedure has been shown to decrease opioid requirements and hospital length of stay; however, few studies have evaluated the impact on complications and hospital costs.

METHODS

A retrospective cohort study was performed for all Nuss procedures at our institution from 2016 through 2020. Outcomes were compared across 4 pain modalities: cryoablation with standardized pain regimen (n = 98), patient-controlled analgesia (PCA; n = 96), epidural (n = 36), and PCA with peripheral nerve block (PNB; n = 35). Outcomes collected included length of stay, opioid use, variable direct costs, and postoperative complications. Univariate and multivariate hierarchical regression analysis was used to compare outcomes between the pain modalities.

RESULTS

Cryoablation was associated with increased total hospital cost compared with PCA (cryoablation, $11 145; PCA, $8975; P < .01), but not when compared with epidural ($9678) or PCA with PNB ($10 303). The primary driver for increased costs was operating room supplies (PCA, $2741; epidural, $2767; PCA with PNB, $3157; and cryoablation, $5938; P < .01). With multivariate analysis, cryoablation was associated with decreased length of stay (-1.94; 95% CI, -2.30 to -1.57), opioid use during hospitalization (-3.54; 95% CI, -4.81 to -2.28), and urinary retention (0.13; 95% CI, 0.05-0.35).

CONCLUSIONS

Cryoablation significantly reduces opioid requirements and length of stay relative to alternative modalities, but it was associated with an increase in total hospital costs relative to PCA, but not epidural or PCA with PNB. Cryoablation was not associated with allodynia or slipped bars requiring reoperation.

Intercostal Nerve Cryoablation for Postoperative Pain Control in Pediatric Thoracic Surgery: A Scoping Review

Background: Cryoanalgesia uses the application of cold temperatures to temporarily disrupt peripheral sensory nerve function for pain control. This review outlines the principles of cryoablation, clinical applications, and clinical data for its use in pediatric thoracic surgery. Methods: A comprehensive PubMed search was performed using the principal terms and combinations of cryoablation, cryoanalgesia, Nuss, Nuss repair, pectus, pectus excavatum, thoracic surgery, thoracotomy, and chest wall. Pediatric articles were reviewed and included if relevant. Adult articles were reviewed for supporting information as needed. Reference lists of included articles were reviewed for possible additional sources. Discussion: The scientific and clinical principles of cryoablation are outlined, followed by a focused review of current clinical application and outcome data. Conclusion: Postoperative pain is a major challenge following thoracic surgery. Cryoanalgesia is emerging as an adjunct in pediatric thoracic surgery, particularly for the Nuss procedure or minimally invasive repair of pectus excavatum. It effectively controls pain, decreasing postoperative opioid use and hospital length of stay with few short-term complications. Although more long-term studies are needed, early evidence suggests there is reliable return of sensation to the chest wall and long-term neuropathic pain is rare.

Intercostal nerve cryoablation during surgical stabilization of rib fractures decreases post-operative opioid use, ventilation days, and intensive care days

BACKGROUND

Intercostal nerve cryoablation is an adjunctive measure that has demonstrated pain control, decrease in opioid consumption, and decrease in hospital length of stay (LOS) in patients who undergo surgical stabilization of rib fractures (SSRF).

METHODS

SSRF patients from January 2015 to September 2021 were retrospectively compared. All patients received multimodal pain regimens post-operatively and the independent variable was intraoperative cryoablation.

RESULTS

241 patients met inclusion criteria. 51 (21%) underwent intra-operative cryoablation during SSRF and 191 (79%) did not. Patients with standard treatment consumed 9.4 more daily MME (p = 0.035), consumed 73 percent more post-operative total MME (p = 0.001), spent 1.55 times as many days in the intensive care unit (p = 0.013), and spent 3.8 times as many days on the ventilator than patients treated with cryoablation, respectively. Overall hospital LOS, operative case time, pulmonary complications, MME at discharge, and numeric pain scores at discharge were no different (all p>0.05).

CONCLUSION

Intercostal nerve cryoablation during SSRF is associated with fewer ventilator days, ICU LOS, total post-operative, and daily opioid use without increasing time in the operating room or perioperative pulmonary complications.

A Randomized Controlled Trial of Cryoanalgesia for Pain Management following Pectus Excavatum Repair: A Single-Center, Single-Blind, Parallel Design Study

INTRODUCTION

 Conventional postoperative pain management, with an intravenous patient-controlled approach or thoracic epidural analgesia, has proved suboptimal following a minimally invasive repair of pectus excavatum. Considering its postulated mechanism of action, we encouraged cryoanalgesia as an effective method for postrepair pain management and a possibly superior alternative.

METHODS

 A randomized, single-blind clinical trial was tested on patients undergoing pectus excavatum (PE) repair in March and December 2022. Among 101 patients, consenting study participants were randomly assigned to one of two groups: cryoanalgesia (group C, n = 24) or noncryoanalgesia (group N, n = 24). Group N received conventional pain management. Comparing the results, pain levels were measured using the visual analog scale (VAS-R for resting and VAS-D for dynamic) and the total rescue analgesic consumption was determined. Intrathoracic cryoablation was performed bilaterally on the fourth and seventh intercostal nerves using a cryoprobe at -80°C for 2 minutes.

RESULTS

 The two groups had similar baseline-patient characteristics; however, group C had a longer mean operative time (159 vs. 125 minutes, p < 0.01) and experienced significantly less pain throughout the postoperative course, with VAS at 6 hours (5.38 vs. 7.04, p < 0.01) and 48 hours (3.17 vs. 5.67, p < 0.01).

CONCLUSION

 Cryoanalgesia improved postoperative pain control at rest and during movement following PE repair. However, the outcome was less favorable than expected because the VAS was greater than 4 (moderate pain), although after a day or two, it decreased to lower levels (VAS < 4) in the cyro group. Considering its extra invasiveness and instrumentation, a routine cryoanalgesia procedure for pectus surgery is yet to be determined.

Intercostal nerve cryoablation therapy for the repair of pectus excavatum: a systematic review

Introduction

The minimally invasive repair of pectus excavatum (PE) is a painful procedure that can result in long-term hospitalization and opioid use. To mitigate the length of stay and opioid consumption, many different analgesia strategies have been implemented. The aim of this study is to review the use and patient outcomes of intercostal nerve cryoablation (INC) during PE repair reported in the literature.

Methods

An unfunded literature search using PubMed identifying articles discussing INC during PE repair from 1946 to 1 July 2023 was performed. Articles were included if they discussed patient outcomes with INC use during PE repair. Articles were excluded if they were reviews/meta-analyses, editorials, or not available in English. Each article was reviewed for bias by analyzing the study methods, data analysis, patient selection, and patient follow-up. Articles comparing outcomes of INC were considered significant if p-value was <0.05.

Results

A total of 34 articles were included in this review that described INC use during pectus repair. Most supported a decreased hospital length of stay and opioid use with INC. Overall, INC was associated with fewer short-term and long-term complications. However, the researchers reported varied results of total hospital costs with the use of INC.

Conclusion

The review was limited by a paucity of prospective studies and low number of patients who received INC. Despite this, the present data support INC as a safe and effective analgesic strategy during the repair of PE.

Multicenter Assessment of Cryoanalgesia Use in Minimally Invasive Repair of Pectus Excavatum: A 20-center Retrospective Cohort Study

OBJECTIVE

To assess the clinical implications of cryoanalgesia for pain management in children undergoing minimally invasive repair of pectus excavatum (MIRPE).

BACKGROUND

MIRPE entails significant pain management challenges, often requiring high postoperative opioid use. Cryoanalgesia, which blocks pain signals by temporarily ablating intercostal nerves, has been recently utilized as an analgesic adjunct. We hypothesized that the use of cryoanalgesia during MIRPE would decrease postoperative opioid use and length of stay (LOS).

MATERIALS AND METHODS

A multicenter retrospective cohort study of 20 US children's hospitals was conducted of children (age below 18 years) undergoing MIRPE from January 1, 2014, to August 1, 2019. Differences in total postoperative, inpatient, oral morphine equivalents per kilogram, and 30-day LOS between patients who received cryoanalgesia versus those who did not were assessed using bivariate and multivariable analysis. P value <0.05 is considered significant.

RESULTS

Of 898 patients, 136 (15%) received cryoanalgesia. Groups were similar by age, sex, body mass index, comorbidities, and Haller index. Receipt of cryoanalgesia was associated with lower oral morphine equivalents per kilogram (risk ratio=0.43, 95% confidence interval: 0.33-0.57) and a shorter LOS (risk ratio=0.66, 95% confidence interval: 0.50-0.87). Complications were similar between groups (29.8% vs 22.1, P =0.07), including a similar rate of emergency department visit, readmission, and/or reoperation.

CONCLUSIONS

Use of cryoanalgesia during MIRPE appears to be effective in lowering postoperative opioid requirements and LOS without increasing complication rates. With the exception of preoperative gabapentin, other adjuncts appear to increase and/or be ineffective at reducing opioid utilization. Cryoanalgesia should be considered for patients undergoing this surgery.

Cost and outcomes of intercostal nerve cryoablation versus thoracic epidural following the Nuss procedure

BACKGROUND

Pectus excavatum is the most common congenital chest wall abnormality, with the Nuss procedure being the most commonly performed repair. Pain control is the predominant factor in the postoperative treatment of these patients. This study aims to compare the cost and outcomes of intercostal nerve cryoablation (INC) and thoracic epidural (TE) in patients undergoing the Nuss procedure.

METHODS

A retrospective chart review was conducted at our institution for all patients who underwent the Nuss procedure for pectus excavatum from 2002 to 2020. Patients were stratified by pain management strategy, INC vs. TE. Chi-square and Fisher's exact were used to compare categorical variables. Wilcoxon tests were used to evaluate continuous variables and costs.

RESULTS

A total of 158 patients were identified. Of these, 80.4% (N = 127) were treated with epidural, while 19.6% (N = 31) were treated with intercostal nerve cryoablation. The INC group had lower rates of PCA use (35.5% vs. 93.7%, p < 0.001), lower total morphine milligram equivalent requirement (27.0 vs. 290.8, p < 0.001), and shorter length of stay (3.2 days vs. 5.3 days, p < 0.001) compared to the TE group. INC was also associated with longer operative times (153.0 min vs. 89.0 min, p < 0.001). The total hospitalization cost for the INC group was higher compared to the TE group ($24,742.5 vs $21,621.9, p = 0.001).

CONCLUSIONS

In patients undergoing the Nuss procedure, compared to thoracic epidural, INC was associated with lower opioid use and shorter length of stay but at the cost of longer operative time and increased hospitalization cost.

LEVEL OF EVIDENCE

Treatment Study, Level III.

A pilot study of multi-modal pain management for same-day discharge after minimally invasive repair of pectus excavatum (Nuss procedure) in children

BACKGROUND

Despite advancements in minimally invasive repair of pectus excavatum (MIRPE), Nuss procedure, postoperative pain control remains challenging. This report covers a multimodal regimen using bilateral single-shot paravertebral block (PVB) and bilateral thoracoscopic intercostal nerve (T3-T7) cryoablation, leading to significant reduction in length of stay (LOS) and high rate of same-day discharge.

METHODS

This is a comparative study of pain management protocols for patients undergoing the Nuss procedure at a single center from 2016 through 2020. All patients underwent the the same surgical technique for the treatment of pectus excavatum at a single center. Patients received bilateral PVB with continuous infusion (Group 1, n = 12), bilateral PVB with infusion and right-side cryoablation (Group 2, n = 9), or bilateral single-shot PVB and bilateral cryoablation (Group 3, n = 17). The primary outcome was LOS with focus on same-day discharge, and the secondary outcome was decreased opioid usage.

RESULTS

Eleven of 17 patients in Group 3 (65%) (bilateral single-shot PVB and bilateral cryoablation) were discharged the same day as surgery. The remaining Group 3 patients were discharged the following day with no complications or interventions. Compared to Group 1 (no cryoablation), Group 3 had shorter LOS (median 4.4 days vs. 0.7 days, respectively, p < 0.001) and significantly decreased median opioid use on the day of surgery (0.92 mg/kg vs. 0.47 mg/kg, p = 0.006).

CONCLUSION

Findings demonstrate the feasibility of multimodal pain management for same-day discharge after the Nuss procedure. Future multisite studies are needed to investigate the superiority of this approach to established methods.

LEVEL OF EVIDENCE

III.

Intercostal Nerve Cryoablation is Associated with Reduced Opioid Use in Pediatric Oncology Patients

INTRODUCTION

Intercostal nerve cryoablation reduces postoperative pain in adults undergoing thoracotomy and children undergoing pectus excavatum repair. We hypothesize that cryoablation is associated with decreased post-thoracotomy pain and opioid use in pediatric oncology patients.

METHODS

A single-center retrospective cohort study was performed for oncology patients who underwent thoracotomy from January 1, 2017 to May 31, 2021. Outcomes included postoperative opioid use measured in morphine milligram equivalents per kilogram (MME/kg), pain scores (scale 0-10), and opioid prescription at discharge. Univariable analysis compared patients who received cryoablation to patients who did not receive cryoablation. Multivariable regression analysis controlling for age and prior thoracotomy evaluated associations between cryoablation and postoperative pain.

RESULTS

Overall, 32 patients (19 males:13 females) underwent thoracotomy with 16 who underwent >1 thoracotomy resulting in 53 thoracotomies included for analysis. Cryoablation was used in 14 of 53 (26.4%) thoracotomies. Throughout the postoperative hospitalization, patients receiving cryoablation during thoracotomy consumed less opioids compared to patients who did not receive cryoablation (median 0.38 MME/kg, interquartile range [IQR] 0.20-1.15 versus median 1.47 MME/kg, IQR 0.71-4.02, P < 0.01). Maximum pain scores were lower in cryoablation patients (median 6, IQR 5-8) than noncryoablation patients (median 8, IQR 6-10), with a significant difference observed on postoperative day 4 (P = 0.01). Cryoablation patients were also less frequently prescribed opioids at discharge (21.4% versus 58.97%, P = 0.02). Multivariable regression demonstrated that cryoablation was associated with 2.59 MME/kg less opioid use (95% confidence interval -4.56 to -0.63) and decreased likelihood of opioid prescription at discharge (adjusted odds ratio 0.14, 95% confidence interval 0.03-0.67).

CONCLUSIONS

Cryoablation is significantly associated with decreased post-thoracotomy pain and opioid use in pediatric cancer patients and should be considered in postoperative pain regimens.

Impact of Cryoanalgesia Use During Minimally Invasive Pectus Excavatum Repair on Hospital Days and Total Hospital Costs Among Pediatric Patients

INTRODUCTION

Surgical repair of pectus excavatum is a painful procedure requiring multimodal pain control with historically prolonged hospital stay. This study aimed to evaluate the impact of cryoanalgesia during minimally invasive repair of pectus excavatum (MIRPE) on hospital days (HDs), total hospital costs (HCs), and complications. We hypothesized that cryoanalgesia would be associated with reduced HDs and total HCs with no increase in post-operative complications.

METHODS

We conducted a retrospective review of pediatric patients who underwent MIRPE from 2011 to 2021. MIRPE details and post-operative outcomes within 90 days were abstracted. Total HDs included the index MIRPE admission and readmissions within 90 days. HCs were obtained from the hospital accounting system, retroactively adjusting for medical inflation. Bayesian generalized linear models with neutral prior assuming no effect were used. Differences between treatment groups were assessed using gamma distribution (HDs and HCs) and poisson (post-operative complications). All models used log link and controlled for age, gender, race, and Haller index.

RESULTS

Forty-four patients underwent MIRPE during the study period. Cryoanalgesia was utilized in 29 (66%) patients. The probability of a reduction with cryoanalgesia vs. no cryoanalgesia was 99% for HDs (3.0 vs. 5.4 days; Bayesian RR: 0.6, 95% CrI: 0.5-0.8), 89% for HCs ($18,787 vs. $19,667; RR: 0.9, 95% CrI: 0.8-1.1), and 70% for postoperative complications (17% vs 33%; RR: 0.8, 95% CrI: 0.3-1.9).

CONCLUSION

Cryoanalgesia use in MIRPE likely reduced HDs, HCs, and post-operative complications. Further research is warranted to confirm these findings in large prospective studies.

LEVEL OF EVIDENCE

Level III.

Implementation of a Cryoablation-based Pain Management Protocol for Pectus Excavatum

INTRODUCTION

The Nuss repair for pectus excavatum is associated with significant postoperative pain. Our institution developed protocols to standardize pain management for pectus excavatum patients in the immediate postoperative period. We present our experience with protocol implementation and patient outcomes.

METHODS

We standardized regional anesthesia with a 0.25% bupivacaine incisional soaker catheter (post-implementation 1, PI1) before transitioning to intercostal nerve cryoablation (INC) (post-implementation 2, PI2). Patient outcomes were tracked using statistical process control charts in AdaptX™ OR Advisor and run charts in Tableau. Chi-squared tests assessed demographic differences between cohorts.

RESULTS

244 patients were included: 78 pre-implementation, 108 PI1, and 58 PI2. Average age was 15.9-16.5 years. Patients were majority male, non-Hispanic white, and English speaking. Hospital length of stay decreased 4.1-2.4 days. INC increased surgery time (99-125 min) but decreased PACU time (112-78 min). Maximum pain scores improved in PACU (7.7-6.0) and 0-24 h postoperatively (8.3-6.8) but were not different 24-48 h postoperatively (5.4-5.8). Average opioid dosing decreased 0-48 h from 1.9 to 0.8 mg/kg morphine milliequivalents and was associated with reduction in post-operative nausea and constipation. There were no 30-day readmissions.

CONCLUSION

An institution-wide pain management protocol using INC for pectus excavatum patients was implemented. Intercostal nerve cryoablation was found to be superior to bupivacaine incisional soaker catheters and reduced hospital length of stay, immediate postoperative pain scores, morphine milliequivalent opioid dosing, postoperative nausea, and constipation.

LEVEL OF EVIDENCE

Level IV.

Intercostal Nerve Cryoanalgesia Versus Thoracic Epidural Analgesia in Lung Transplantation: A Retrospective Single-Center Study

INTRODUCTION

The optimal pain management strategy after lung transplantation is unknown. This study compared analgesic outcomes of intercostal nerve blockade by cryoanalgesia (Cryo) versus thoracic epidural analgesia (TEA).

METHODS

Seventy-two patients who underwent bilateral lung transplantation via clamshell incision at our center from 2016 to 2018 were managed with TEA (N = 43) or Cryo (N = 29). We evaluated analgesic-specific complications, opioid use in oral morphine equivalents (OME), and pain scores (0-10) through postoperative day 7. Adjusted linear regression was used to assess for non-inferiority of Cryo to TEA.

RESULTS

The overall mean pain scores (Cryo 3.2 vs TEA 3.8, P = 0.21), maximum mean pain scores (Cryo 4.7 vs TEA 5.5, P = 0.16), and the total opioid use (Cryo 484 vs TEA 705 OME, P = 0.12) were similar in both groups, while the utilization of postoperative opioid-sparing analgesia, measured as use of lidocaine patches, was lower in the Cryo group (Cryo 21% vs TEA 84%, P < 0.001). Analgesic outcomes remained similar between the cohorts after adjustment for pertinent patient and analgesic characteristics (P = 0.26), as well as after exclusion of Cryo patients requiring rescue TEA (P = 0.32). There were no Cryo complications, with four patients requiring subsequent TEA for pain control. Two TEA patients experienced hemodynamic instability following a test TEA bolus requiring code measures. Additionally, TEA placement was delayed beyond postoperative day 1 in 33% owing to need for anticoagulation or clinical instability.

CONCLUSIONS

In lung transplantation, Cryo was found to be safe with analgesic effectiveness similar to TEA. Cryo may be advantageous in this complex patient population, as it can be used in all clinical scenarios and eliminates risks and delays associated with TEA.

Case Report of Cryo Nerve Block in a Patient Undergoing Full Sternotomy: A Novel Approach to Pain Control in Cardiac Surgery

We present the case of a 65-year-old man undergoing open-heart surgery through a full sternotomy with the use of bilateral intercostal cryo nerve block (cryoNB) as adjunctive therapy for postoperative analgesia. CryoNB has been previously demonstrated as safe and effective for pain control in thoracotomy procedures as well as bilaterally in adolescent patients with pectus excavatum undergoing Nuss procedure. Herein, we describe for the first time, the cryoNB procedure for postoperative pain management in a patient undergoing full sternotomy.

Ultrasound-Guided Percutaneous Cryoanalgesia for Pectus Excavatum: When Should It be Applied?

INTRODUCTION

 The addition of ultrasound-guided percutaneous cryoanalgesia (PCr) for pain management after pectus excavatum (PE) surgery offers a new and advantageous approach. Our aim is to describe our experience with PCr applied on the same day, 24 hours, and 48 hours prior to PE surgery.

MATERIAL AND METHODS

 Prospective pilot study in patients undergoing ultrasound-guided PCr (2019-2022) was divided into three groups: PCr on the same day of surgery (PCrSD), PCr 24 hours before (PCr24), and PCr 48 hours before (PCr48). We describe the application of technique and data obtained by comparing the three groups.

RESULTS

 We present 42 patients (25 PCrSD, 11 PCr24, 6 PCr48). PCr24 had a shorter procedure duration than PCrSD (65.8 vs. 91.2 minute; p = 0.048). Related to analgesia, PCr24 and PCr48 showed lower opioid consumption than PCrSD in PCA volume (48.5 and 49.6 vs. 75.1 mL; p = 0.015) and PCA time (23.3 and 23.8 vs. 34.3 hours; p = 0.01). Degree of pain (VAS scale) on the day of surgery and on the second postoperative day was lower in PCr24 and PCr48 than in PCrSD (4 and 2 vs. 5; p = 0.012; 0 and 1 vs. 2; p = 0.01, respectively) as well as shorter hospital stay (3 and 3.5 vs. 5 days; p = 0.021). In addition, PCr24 showed lower opioid consumption and hospital stay than PCr48 (p > 0.05). The greatest savings in hospital costs were obtained in the PCr24 group.

CONCLUSION

 PCr48 and PCr24 prior to PE surgery offers lower opioid consumption, less pain and shorter hospital stay than PCrSD. PCr24 is comparable to PCr48, but seems to show advantages and simpler logistics for the patient and the hospital.

Effectiveness of one minute per level intercostal nerve cryoablation for postoperative analgesia after surgical correction of pectus excavatum

PURPOSE

Intraoperative intercostal nerve cryoablation has emerged as a promising modality for postoperative analgesia following Surgical Correction of Pectus Excavatum (SCOPE). Most centers use two-minute cryoablation per level, although data from histologic and adult studies suggest the effectiveness of one-minute freezes. We aimed to describe our center's experience with one minute per level cryoablation.

METHODS

A retrospective single institution review of patients undergoing SCOPE was performed to compare patients pre- and post-intercostal nerve cryoablation implementation. Cryoablation was performed as one minute for each of the thoracic intercostal nerves T3-T7. Multivariable regression analyses were conducted to compare the outcomes and cost between pre- and post-implementation groups.

RESULTS

During the study period, 198 patients underwent SCOPE with one Nuss bar, receiving either intraoperative intercostal nerve cryoablation (Cryo, n = 100) or preoperative thoracic paravertebral catheters (NoCryo, n = 98). Surgical time was on average 9 min longer for the Cryo group (p<0.01). Median length of stay for the Cryo group was 3 days shorter compared to the NoCryo group (p<0.01). The Cryo group had a 19-fold and 5.6-fold reduction in average inpatient and total postoperative opioid usage, respectively (p<0.01). Total hospital costs were significantly lower in the Cryo group (p<0.01). Overall complication rate was not statistically significant different between the two groups.

CONCLUSIONS

Intraoperative one minute per level cryoablation is a potent approach to postoperative analgesia for SCOPE patients that led to a shorter hospital length of stay, lower hospital costs, and decreased opioid use compared to conventional analgesia at our institution. Pediatric surgeons performing correction of chest wall deformities should consider offering this technique.

Cryoablation in 350 Nuss procedures: Evolution of hospital length of stay and opioid use

INTRODUCTION

Current studies show cryoablation decreases opioid requirements and lengths of stay (LOS) in patients undergoing the Nuss procedure for pectus excavatum. This study evaluated the relationship between cryoablation and clinical outcomes for the Nuss procedure.

METHODS

A retrospective single-center chart review was performed on patients undergoing the Nuss procedure with intercostal cryoablation from December 2017-August 2021. Demographics, hospital course, and postoperative complications were abstracted. To evaluate the evolution of outcomes over time, the earliest quarter (Q1) of cryoablation patients was compared to the last quarter (Q4).

RESULTS

Over 45 months, 350 Nuss procedures with cryoablation were performed. The mean age at operation was 15.7 ± 2.3 years with an average Haller Index of 5.4 ± 4.2. The mean operative time was 136 ± 40.5 minutes. On average, patients used 2.8 ± 2.5 OME/kg of opioid in hospital with a LOS of 2.7 ± 1.1 days. The Q4 patients were discharged 1.3 days earlier (p<0.05) than Q1 patients, with 80% of Q4 discharged by postoperative day #2 vs. 23% in Q1 (p<0.05). Q4 patients received 74% (p<0.05) less opioid in hospital and 21% (p<0.05) less on discharge. Within 90 days postoperatively, complication rates (chest tube placement, wound infection, readmission, neuropathic pain) were similar. Only two patients (0.6%) required reoperation for bar migration/slippage.

CONCLUSION

With increased experience, cryoablation for the Nuss procedure decreased opioid use by 74% and was associated with 80% of patients achieving early discharge. Major complication rates were not increased. Cryoablation can be successfully implemented as an effective method of postoperative analgesia.

LEVEL OF EVIDENCE

Level III.

Neurolysis for analgesia following pectus repair in a national cohort

INTRODUCTION

Pectus excavatum and pectus carinatum are the most common chest wall deformities of childhood. Surgical repair can be complicated by post-operative analgesic challenges. Thoracic epidural analgesia, patient-controlled analgesia, and multimodal pain control are among the most common strategies. We sought to define the current utilization of intraoperative thoracic neurolysis, hypothesizing that this would minimize length of stay (LOS) and post-operative narcotic use with relatively higher proportion of non-narcotic post-operative analgesia.

METHODS

We performed a retrospective review of the Pediatric Health Information System (PHIS) database between 2017 and 2020. We first identified patients who underwent a pectus repair via ICD-10-PCS codes. We used ICD-10-PCS codes 01580ZZ and 01584ZZ to identify those patients who underwent concomitant thoracic neurolysis. Statistical analyses were performed using R; p value less than 0.05 was considered significant.

RESULTS

We identified 2979 patients who underwent a pectus repair. 184 underwent a concomitant thoracic nerve destruction procedure (6.7%); 13 were performed in 2017 (2.01%), 76 in 2018 (10.7%), and 84 in 2019 (9.6%). LOS was shorter in those patients who underwent neurolysis (mean=2.55 vs 3.73 days, SD=1.33 vs 1.78 days, p<0.001). There were fewer post-operative ICU admissions in neurolysis patients (3/184 vs. 193/2795, p = 0.003). The cost of procedures that included a neurolysis were higher, though not significantly so (mean=$24,885.64 vs $22,200.59).

CONCLUSION

Thoracic neurolysis may be a useful analgesic strategy, expediating post-operative discharge and potentially obviating the need for intensive care. Further larger-scale prospective trials should be considered to further elucidate the role of this analgesia method.

LEVEL OF EVIDENCE

Level III.

Same day discharge for pectus excavatum-is it possible?

PURPOSE

The use of intercostal nerve cryoablation (INC) has been an effective modality for treating pain in patients undergoing pectus excavatum (PE) repair. This study sought to evaluate if PE patients undergoing Nuss procedures with INC and intercostal nerve block (INB) could safely be discharged the same day of surgery.

METHODS

A prospective study with IRB approval of 15 consecutive patients undergoing PE Nuss repair with INC, INB, and an enhanced recovery after surgery (ERAS) protocol was conducted. The primary outcome measure was hospital length of stay (LOS) in hours. Secondary variables included same day discharge, postoperative complications, emergency department (ED) visits, urgent care (UC) visits, opioid use, and return to the operating room (OR).

RESULTS

LOS averaged 11.9 h amongst 15 patients. Ten patients (66.7%) went home on postoperative day (POD) 0, and the rest went home on POD 1. No patients stayed in the hospital due to pain. Reasons for failure to discharge included urinary retention, drowsiness, vomiting, and anxiety, but not pain. No patients were readmitted to the ED. One patient visited UC for constipation. One patient had bar migration requiring return to the OR for revision. Ten (66.7%) patients did not use opioids after discharge.

CONCLUSIONS

Same day discharge is feasible and safe in PE patients undergoing Nuss procedure with INC and INB. INC with INB can adequately control pain without significant complications. Same day discharge can be safely considered for PE patients undergoing Nuss procedure with INC with INB.

TYPE OF STUDY

Prognosis study LEVEL-OF-EVIDENCE RATING: Level II.

Extending Perioperative Analgesia with Ultrasound-Guided, Percutaneous Cryoneurolysis, and Peripheral Nerve Stimulation (Neuromodulation)

The use of regional anesthesia is key to a successful approach to improving postoperative analgesia, which involves local anesthetic deposition either around peripheral nerves or within a fascial plane. Unfortunately, the realistic duration even with continuous peripheral nerve blocks usually does not match the duration of surgical pain, comprising a major limitation. Here, the use of 2 interventional modalities-ultrasound-guided percutaneous cryoneurolysis and peripheral nerve stimulation-is discussed, both of which may be used to treat acute and subacute pain and may therefore have a positive impact on the incidence and severity of chronic pain development.

Limited cryoablation reduces hospital stay and opioid consumption compared to thoracic epidural analgesia after minimally invasive repair of pectus excavatum

pain following minimally invasive repair of pectus excavatum (MIRPE) is a critical concern that leads to a prolonged hospital stay and high doses of opiates administered to the patients. This study aimed to evaluate the efficacy of intraoperative cryoanalgesia (cryoablation of the intercostal nerves) during MIRPE. We retrospectively analyzed the data of 64 patients who underwent MIRPE and received cryoanalgesia or epidural analgesia between January 2019 and January 2021. The oral morphine milligram equivalent (MME) was used to calculate the dosage of opioid agents. The median age was 15 years (range, 4-33 years). The median postoperative hospital stay was 4 days (range, 2-6 days), with a median oral MME consumption of 45 mg (ranging from 0 to 1360 mg). Cryoanalgesia was performed in 38 patients, and epidural analgesia was administered to the remaining 26 patients. The cryoanalgesia group had a significantly lesser pain score, shorter postoperative hospital stay and lower oral MME consumption than the epidural analgesia group (5 vs 2; P < .001, 3 days vs 5 days; P < .001, 19 mg vs 634 mg; P < .001). Cryoanalgesia appears to reduce postoperative hospital stay and opioid consumption compared with epidural analgesia. The outcomes of this study indicate that cryoanalgesia might be a safe and effective method for pain control following MIRPE.

Variations in Nuss Procedure Operative Techniques and Complications: A Retrospective Review

INTRODUCTION

 The Nuss procedure is the most common and preferred operative correction of pectus excavatum. Surgeon preference and patient factors can result in variations in Nuss procedure technique. We hypothesize that certain techniques are associated with increased risk of complications.

MATERIALS AND METHODS

 We performed a single-center retrospective review of Nuss operations from 2016 to 2020. Variations in intraoperative techniques included sternal elevator (SE) use, number of bars placed, and usage of bilateral stabilizing sutures. Patient demographics, intraoperative data, and postoperative outcomes were reported as median with interquartile ranges or percentages. Statistical significance (p < 0.05) was determined with Wilcoxon's rank-sum and chi-square tests. Multivariate analysis was performed to control for introduction of intercostal nerve cryoablation and surgeon volume, and reported as odds ratio with 95% confidence interval.

RESULTS

 Two hundred and sixty-five patients were identified. Patients repaired with two bars were older with a larger Haller index (HI). Patient demographics were not significantly different for SE or stabilizing suture use. Placement of two bars was associated with significantly increased risk of readmission. Similarly, SE use was associated with increased risk of pleural effusion and readmission. Finally, the use of bilateral stabilizing sutures resulted in less frequent slipped bars without statistical significance.

CONCLUSION

 Older patients with a larger HI were more likely to need two bars placed to repair pectus excavatum. Placement of multiple bars and SE use are associated with significantly higher odds of certain complications.

Intercostal Cryoneurolysis

Chest wall pain affects many patients following chest surgery, fractures, or malignancies, and can be very difficult to manage with normal pharmacologic agents. Intercostal ablation provides one alternative treatment modality for patients suffering from intercostal pain. Intercostal cryoneurolysis involves using extreme cold to cause Wallerian degeneration of the targeted intercostal nerve. This article reviews the patient selection, technique, and complications in the utilization of intercostal neurolysis in the treatment of intractable chest pain.

Managing Pain and Discomfort in Children with Cancer

PURPOSE OF REVIEW

Approximately 15,600 children are diagnosed with cancer annually. Many of these children have cancer-related pain that improves with cancer treatment, but some develop intractable pain from cancer progression or sequelae from treatment modalities. The purpose of this paper is to provide a critical evaluation of the literature relevant to pain management in children with cancer. We intend to emphasize important and up-to-date findings in pharmacology, interventional pain management, and complementary and alternative medicine.

RECENT FINDINGS

Alternative medications and routes of administration, complementary and alternative medicine techniques, and interventional pain procedures offer possible routes for a multi-pronged pediatric cancer pain management plan, although high-level data is often lacking. To improve pediatric cancer pain management, a multifaceted approach embracing the biopsychosocial model of pain is recommended, incorporating evidence-based pharmacology, complementary and alternative medicine techniques, and if needed, interventional pain procedures.

Next day discharge after the Nuss procedure using intercostal nerve cryoablation, intercostal nerve blocks, and a perioperative ERAS pain protocol

BACKGROUND

The Nuss procedure for pectus excavatum has historically been associated with significant postoperative pain, which has been the major factor contributing to hospital length of stay (LOS).

METHODS

A single-institution, prospective study of 40 consecutive patients undergoing Nuss bar placement for pectus excavatum between November 2019 and January 2021 was conducted to assess the effectiveness of a multimodality pain management protocol. All patients received T3-T8 intercostal nerve cryoablation (INC), T3-T8 bupivacaine intercostal nerve blocks, Exparel at the skin incisions, and management with a perioperative analgesia regimen that minimized narcotic usage. The primary outcome was LOS. Secondary outcomes included opioid use, pain scores, and time to sensory recovery.

RESULTS

37/40 patients (92.5%) were discharged home on postoperative day (POD) 1, and 3/40 (7.5%) were discharged on POD 2 (mean LOS = 1.1 days). The median average postoperative pain score was 2/10. After eliminating IVPCA from our protocol, total oral morphine equivalent (OME) decreased by 73% (55.5 mg to 15 mg) with no change in pain scores or discharge timing.

CONCLUSIONS

INC combined with bupivacaine intercostal nerve blocks and a pre- and post-hospital analgesia protocol facilitated discharge one day after the Nuss procedure, achieved excellent pain control, and eliminated the need for intravenous opioids.

Ultrasound-guided erector spinae plane block versus thoracic epidural analgesia: Postoperative pain management after Nuss repair for pectus excavatum

AIM OF THE STUDY

Postoperative pain management is a significant challenge in patients undergoing Nuss repair for pectus excavatum chest wall deformity. Therapeutic anesthetic options primarily include patient-controlled intravenous analgesia, thoracic epidural analgesia (TEA), and cryoanalgesia. However, TEA is limited to inpatient use and both TEA and cryoanalgesia can result in neurologic injury. The novel technique of ultrasound-guided erector spinae plane regional analgesia has been used recently in our patients undergoing the Nuss repair and has shown impressive pain relief, but without the potential complications of other modalities. Erector spinae plane block (ESPB) postoperative pain management outcomes were studied as compared to TEA.

METHODS

Thirty consecutive patients with severe pectus excavatum undergoing Nuss repair and placement of ultrasound-guided ESPB were each paired to a historical cohort control patient with TEA postoperative pain management. The cohort patient match was defined by age (± 2 years), gender, and CT pectus index (± 15%). Study variables included hospital length of stay (LOS), pain scores, and pain medication usage.

RESULTS

Pain scores as measured by area under the curve per hour (Day 1: 2.72 (SD = 1.37) vs. 3.90 (SD = 1.81), P = 0.006; Day 2: 2.83 (SD = 1.32) vs. 3.97 (SD = 1.82), P = 0.007) and oral morphine equivalent (OME) pain medication usage (Day 1: 11.9 (SD = 4.9) vs 56.0 (SD = 32.2), P < 0.001; Day 2: 14.7 (SD = 7.1) vs. 38.0 (SD = 21.7), P < 0.001) were higher for the first two postoperative days in the ESPB group. However, mean hospital LOS was nearly one day shorter for ESPB patients (3.78 (SD = 0.82) vs. 2.90 (SD = 0.87), P < 0.001) who were discharged home with the catheter in place until removal, typically at 5-7 days postoperatively.

CONCLUSION

Ultrasound-guided ESPB is thus a feasible, safe, and effective alternative to TEA in postoperative pain management after Nuss repair and results in decreased hospital stay.

LEVEL OF EVIDENCE

III.

Percutaneous Cryoanalgesia: A New Strategy for Pain Management in Pectus Excavatum Surgery

INTRODUCTION

 In recent years, pain protocols for pectus excavatum (PE) have incorporated cryoanalgesia through thoracoscopic approach. Since 2019, ultrasound-guided percutaneous cryoanalgesia (PCr) has been applied at our institution, either on the same day as the Nuss procedure or 48 hours before surgery. We carried out a preliminary retrospective review of patients with PE in whom PCr prior to surgery was performed at our institution between 2019 and 2021.

MATERIALS AND METHODS

 Two groups were evaluated: PCr on the same day (PCrSD) and PCr 48 hours before surgery (PCr48). Despite PCr, patients were treated with "patient-controlled analgesia" (PCA) with opioids for at least 24 hours, switching to conventional intravenous analgesia and oral analgesia in the following days. Demographic, clinical-radiological variables, PCA opioid use, pain grade according to the visual analog scale (VAS), and length of stay (LOS) were compared between the groups. A total of 20 patients were included (12 with PCrSD and 8 with PCr48), without significant differences in demographics or clinical-radiological variables. The overall median time of PCr was 65 minutes (55-127), with no differences between the groups.

RESULTS

 PCr48 group presented with significantly lower median number of hours of continuous PCA (24 vs. 32 hours; p = 0.031), lower median number of rescue boluses (11 vs. 18; p = 0.042), lower median VAS in the early postoperative hours (2 vs. 5.5; p = 0.043), and lower median LOS (3.5 vs. 5 days).

CONCLUSION

 PCr performed 48 hours prior to surgery is more effective in terms of PCA requirements, VAS, and LOS when compared with cryoanalgesia on the same day.

A multimodal protocol utilizing liposomal bupivacaine rib blocks leads to opioid reduction in patients undergoing the Nuss procedure

Background

A major challenge associated with the Nuss procedure for pectus excavatum repair is postoperative pain control. Early Recovery Program (ERP) protocols for the Nuss procedure are becoming common, but there is a paucity of experience using liposomal bupivacaine (LB), a long-acting local anesthetic, for rib blocks in this setting. We investigated whether a protocol utilizing LB rib blocks decreased opioid use after the Nuss procedure while achieving equivalent pain control.

Methods

All adolescent patients undergoing the Nuss procedure at our institution between January 2013 and January 2021 were included. Patients were divided into a pre-intervention cohort (n=15), a transition cohort (n=4), and a post-intervention cohort (n=13). Patients in all groups received scheduled acetaminophen and non-steroidals postoperatively. The pre-intervention cohort received an opioid patient-controlled analgesia (PCA) pump postoperatively, with a transition to oral opiates. The transition and post-intervention cohorts received scheduled gabapentin in addition to intraoperative bilateral rib blocks with longer-acting local anesthetic. Rib blocks were performed using 0.25% Bupivacaine in the pre-intervention group. In the transition group, epinephrine (1 mg/kg) was added to 0.25% bupivacaine for the rib block. Following approval in patients aged 13–18 years, 1.3% LB (2.25 mg/kg) was given for a rib block in the post-intervention cohort.

Results

Demographic and clinical variables were equivalent in all groups. Post-intervention patients received 90% fewer opioids [median morphine equivalent (MME) mg/kg] compared to the pre-intervention cohort (0.8 vs. 8.2 MME mg/kg, P<0.0001), with no significant difference in pain scores between groups. Hospital length of stay was decreased among the intervention cohort (3 vs. 4 days, P=0.002).

Conclusions

Significant decreases in opioid use and length of stay after the Nuss procedure were achieved by the implementation of a multimodal ERP for pain management, without increase in patient-reported pain scores.

Same-day discharge following the Nuss repair: A comparison

PURPOSE

Intercostal Nerve Cryoablation (INC) has significantly improved pain control following the Nuss repair of pectus excavatum (PE). This study sought to evaluate patients undergoing the Nuss repair with INC compared to the Nuss repair with an ERAS protocol, INC, and intercostal nerve blocks (INB).

METHODS

In June 2020, a new protocol was implemented involving surgery, anesthesia, nursing, physical therapy, and child life with the goal of safe same day discharge for patients undergoing the Nuss repair. They were compared to a control group who underwent the Nuss repair with INC alone in 2017-2019. The primary outcome measure was hospital length of stay (LOS) in hours, secondary outcomes were number of patients discharged on postoperative day (POD) 0, and returns to the emergency department (ED), urgent care (UC), and operating room (OR).

RESULTS

The characteristics between the groups were the same (Table 1). The mean LOS was 11.8 h in the INB group versus 58.2 h in the INC group, p < 0.01. 10 of 15 patients in the INB group went home on POD 0 (average of 5.5 h postop), versus 0 patients in the INC only group, p < 0.01. Five patients in the INB stayed overnight. Two patients stayed owing to anxiety, one owing to urinary retention, one owing to nausea, and one owing to drowsiness. None stayed for pain control. Four patients in the INC group returned to the ED for pain control, versus 0 in the INB group, and 1 patient in the INB returned to UC for constipation.

CONCLUSIONS

The majority of patients undergoing the Nuss repair of PE with a multidisciplinary regimen of pre and postoperative nursing education, precise intraoperative anesthesia care, performance of direct vision INB and INC, as well as careful surgery can go home on the day of surgery without adverse outcomes or unanticipated returns to the hospital.

LEVEL-OF-EVIDENCE

Level II.

Intercostal cryoablation during Nuss procedure: A large volume single surgeon's experience and outcomes

BACKGROUND

Recent studies have shown intercostal cryoablation(IC) during the Nuss procedure decreases hospital length of stay(LOS) and opioid administration. However, few studies have also evaluated the risk of postoperative complications related to IC.

METHODS

We performed a single center retrospective analysis of all patients who underwent Nuss procedure by one surgeon from 2/2016 to 2/2020, comparing intraoperative IC to other pain management modalities(non-IC). Primary outcomes were postoperative complications, hospital LOS, and opioid administration. Multivariate analysis was performed with outcomes reported as regression coefficients(RC) or odds ratios(OR) with 95% confidence interval.

RESULTS

IC was associated with decreased hospital LOS (RC -1.91[-2.29 to -1.54], less hospital opioid administration (RC -4.28[-5.13 to -3.43]), and less discharge opioid administration (RC -3.82[-5.23 to -2.41]). With respect to postoperative complications, IC decreased the odds of urinary retention (OR 0.16[0.06 to 0.44]); however, increased the odds of slipped bars requiring reoperation (OR 36.65[5.04-266.39]).

CONCLUSIONS

Our single surgeon experience controls for surgeon variability and demonstrates intraoperative IC for the Nuss procedure is an effective pain management modality that decreases hospital LOS and opioid use during hospitalization and at discharge; however, it is associated with increased odds of slipped bars requiring reoperation.

LEVEL OF EVIDENCE

III.

Intercostal nerve cryoablation during surgical stabilization of rib fractures

BACKGROUND

Intercostal nerve cryoablation (IC) offers potential for targeted and durable analgesia for patients with traumatic rib fractures. Our pilot study aimed to investigate thoracoscopic IC's safety, feasibility, and preliminary efficacy for patients undergoing surgical stabilization of rib fractures (SSRF). We hypothesized that concurrent surgical stabilization of rib fractures and intercostal nerve cryoablation (SSRF-IC) is a safe and feasible procedure without immediate or long-term complications.

METHODS

We retrospectively evaluated patients 18 years or older who underwent SSRF (with or without IC) for acute rib fractures at our level I trauma center between September 1, 2019, and September 30, 2020. We performed IC under thoracoscopic visualization (-70°C for 2 minutes per intercostal nerve bundle). Among patients whose only operative procedure during hospitalization was SSRF, we evaluated post-SSRF length of stay, operative times, opioid requirements (oral morphine equivalents), and pain scores (Numerical Rating Scale). Generalized estimating equations compared SSRF and SSRF-IC group outcomes (population mean [robust standard error]). We assessed long-term outcomes of patients who underwent SSRF-IC.

RESULTS

Thirty-four patients (144 ribs) underwent SSRF; of these, 20 patients (135 ribs) underwent SSRF-IC. Patients who did and did not undergo concurrent IC had no significant difference demographic, injury, or hospitalization characteristics. Among 20 patients who did not undergo other operations, 12 underwent SSRF-IC. We did not find significant difference between SSRF and SSRF-IC groups' median operative times or post-SSRF length of stay. Compared with SSRF group, SSRF-IC group did not have statistically significant change in pain score (0.2 [1.5] lower) or opioid use (43.9 [86.1] mg/d greater) between 12 hours before SSRF and last 24 admission hours. Among 17 SSRF-IC patients who followed-up postdischarge (median [range], 160 [9-357] days), one reported mild chest wall paresthesia; no other complications were reported.

CONCLUSION

This pilot study performing 135 intercostal nerve cryoablations on 20 patients suggests that IC is safe and feasible for patients undergoing SSRF. Evaluating IC's analgesic efficacy for rib fractures requires further study.

LEVEL OF EVIDENCE

Therapeutic, Level V.

Cryoanalgesia is Associated With Decreased Postoperative Opioid Use in Minimally Invasive Repair of Pectus Excavatum

BACKGROUND

Postoperative pain control is challenging after pectus excavatum repair. We aimed to understand the impact that cryoanalgesia had on opioid utilization and outcomes of pediatric patients undergoing minimally invasive repair of pectus excavatum (MIRPE).

METHODS

A single-center retrospective cohort study was conducted of all patients (< 18 y) who underwent MIRPE (2011-2019). Patients receiving cryoanalgesia were compared to those who did not. The primary outcome was total postoperative, inpatient, opioid use, measured as milligrams of oral morphine equivalents per kilogram (OME/kg). Univariate and multivariable analyses were performed.

RESULTS

Of 35 patients, 20 received cryoanalgesia (57%). Baseline characteristics were similar. Patients who received cryoanalgesia had a lower opioid requirement: median 2.3 mg OME/kg (IQR 1.2-3.1), versus 4.9 mg OME/kg (IQR 2.9-5.8), P < 0.001. Accounting for receipt of cryoanalgesia, epidural, and/or patient-controlled analgesia, cryoanalgesia was associated with a 3.3 mg OME/kg reduction in opioid use (P < 0.001). Median length of stay (LOS) was shorter in cryoanalgesia patients: 3.1 d (IQR 2.3-3.4), versus 5.1 d (IQR 4.3-5.4), P < 0.001. Complications within 90 d were similar between groups.

CONCLUSIONS

Cryoanalgesia is an effective adjunctive pain control modality for patients undergoing MIRPE. Use of cryoanalgesia was associated with lower postoperative opioid requirements and shorter LOS, without increased short-term complications, and should be considered for enhanced recovery after MIRPE.

Intercostal nerve cryoablation is associated with lower hospital cost during minimally invasive Nuss procedure for pectus excavatum

Minimally invasive repair of pectus excavatum (Nuss procedure) is associated with significant pain, and efforts to control pain impact resource utilization. Bilateral thoracic intercostal nerve cryoablation has been proposed as a novel technique to improve post-operative pain control, though the impact on hospital cost is unknown.

METHODS

We conducted a retrospective study of patients undergoing a Nuss procedure from 2016 to 2019. Patients who received cryoablation were compared to those that received traditional pain control (patient-controlled analgesia or epidural). Outcome variables included postoperative opioid usage (milligram morphine equivalents, MME), length of stay (LOS), and hospital cost.

RESULTS

Thirty-five of 73 patients studied (48%) received intercostal nerve cryoablation. LOS (1.0 vs 4.0 days, p < 0.01) and total hospital cost ($21,924 versus $23,694, p = 0.04) were decreased in the cryoablation cohort, despite longer operative time (152 vs 74 min, p < 0.01). Cryoablation was associated with decreased opioid usage (15.0 versus 148.6 MME, p < 0.01) during the 24 h following surgery and this persisted over the entire postoperative period, including discharge opioid prescription (112.5 vs 300.0 MME, p < 0.01).

CONCLUSION

Bilateral intercostal nerve cryoablation is associated with decreased postoperative opioid usage and decreased resource utilization in pediatric patients undergoing a minimally invasive Nuss procedure for pectus excavatum.

LEVEL OF EVIDENCE

Retrospective comparative study, level III.

Cryoanalgesia enhances recovery from minimally invasive repair of pectus excavatum resulting in reduced length of stay: A case-matched analysis of NSQIP-Pediatric patients

PURPOSE

Pain control is challenging after minimally invasive repair of pectus excavatum (MIRPE). Cryoanalgesia, which temporarily ablates peripheral nerves, improves pain control and may accelerate post-operative recovery. We hypothesized that cryoanalgesia would be associated with shorter length of stay (LOS) in children undergoing MIRPE.

METHODS

A matched cohort study was conducted of children (<18 years) who underwent MIRPE 2016-2018, using the National Surgical Quality Improvement Program-Pediatric database. Each patient who received cryoanalgesia during MIRPE was matched to four controls (no cryoanalgesia). Univariate and multilevel regression analyses were performed.

RESULTS

Thirty-five patients who received cryoanalgesia during MIRPE were matched to 140 controls. Patients who received cryoanalgesia had a LOS reduction with similar secondary outcomes (operative time, rates of complication, reoperation, and readmission). On multilevel regression adjusted for matched groups, cryoanalgesia was associated with a 1.3-day reduction in LOS (95% CI -1.8 to -0.8, p < 0.001). On sensitivity analysis excluding patients with complications, cryoanalgesia remained associated with a LOS reduction.

CONCLUSIONS

Cryoanalgesia is a promising adjunct in the care of pediatric patients undergoing MIRPE. Utilization is associated with a shorter LOS without an increase in operative time or complications. Cryoanalgesia should be considered for inclusion in enhanced recovery strategies for patients undergoing MIRPE.

Efficacy of intercostal cryoneurolysis as an analgesic adjunct for chest wall pain after surgery or trauma: systematic review

Background

There is a critical need for non-narcotic analgesic adjuncts in the treatment of thoracic pain. We evaluated the efficacy of intercostal cryoneurolysis as an analgesic adjunct for chest wall pain, specifically addressing the applicability of intercostal cryoneurolysis for pain control after chest wall trauma.

Methods

A systematic review was performed through searches of PubMed, EMBASE, and the Cochrane Library. We included studies involving patients of all ages that evaluated the efficacy of intercostal cryoneurolysis as a pain adjunct for chest wall pathology. Quantitative and qualitative synthesis was performed.

Results

Twenty-three studies including 570 patients undergoing cryoneurolysis met eligibility criteria for quantitative analysis. Five subgroups of patients treated with intercostal cryoneurolysis were identified: pectus excavatum (nine studies); thoracotomy (eight studies); post-thoracotomy pain syndrome (three studies); malignant chest wall pain (two studies); and traumatic rib fractures (one study). There is overall low-quality evidence supporting intercostal cryoneurolysis as an analgesic adjunct for chest wall pain. A majority of studies demonstrated decreased inpatient narcotic use with intercostal cryoneurolysis compared with conventional pain modalities. Intercostal cryoneurolysis may also lead to decreased hospital length of stay. The procedure did not definitively increase operative time, and risk of complications was low.

Conclusions

Given the favorable risk-to-benefit profile, both percutaneous and thoracoscopic intercostal cryoneurolysis may serve as a worthwhile analgesic adjunct in trauma patients with rib fractures who have failed conventional medical management. However, further prospective studies are needed to improve quality of evidence.

Level of evidence

Level IV systematic reviews and meta-analyses.

[Intercostal nerve cryoablation in correction of pectus excavatum in adults]

OBJECTIVE

To evaluate an effectiveness of cryoanalgesia in older patients with pectus excavatum and to determine feasibility of further research.

MATERIAL AND METHODS

We have developed an original technique of intercostal nerve cryoablation for correction of pectus excavatum in adults. The results of intercostal nerve cryoablation during correction of pectus excavatum in 10 older patients were analyzed.

RESULTS

Postoperative outcomes were followed-up over a period of 4 - 12 months. There were no perioperative surgical complications. In 1 case, moderate pain syndrome persisted for 3 months after surgery (mean VAS score 2±1.3). In 9 months, mean VAS score was 0.6±0.6 in a month after surgery.

CONCLUSION

Intercostal nerve cryoablation in correction of pectus excavatum in adults may be an alternative to the current methods of regional analgesia. Further research is requried to achieve objective information.