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. 2021 Apr 8;147(6):1–9. doi: 10.1001/jamaoto.2021.0327

Postoperative Pain Treatment With Continuous Local Anesthetic Wound Infusion in Patients With Head and Neck Cancer

A Nonrandomized Clinical Trial

Magdalena Gostian 1, Johannes Loeser 1, Carola Albert 1, Philipp Wolber 2, David Schwarz 2, Maria Grosheva 2, Stephanie Veith 2, Christoph Goerg 1, Matthias Balk 3, Antoniu-Oreste Gostian 3,✉
PMCID: PMC8033507  PMID: 33830180

Key Points

Question

Does continuous anesthetic wound infusion provide additional pain relief after head and neck surgery?

Findings

In this nonrandomized clinical trial of 60 patients, postoperative treatment with continuous anesthetic wound infusion was associated with lower average and maximum pain alongside improved quality of life and lower consumption of systemic analgesics.

Meaning

Continuous wound infusion is associated with a reduction in postoperative pain following head and neck surgery.

This nonrandomized clinical trial investigates the association of continuous local anesthetic wound infusion with pain management after head and neck surgery.

Abstract

Importance

Up to 80% of patients with head and neck cancer undergoing ablative surgery and neck dissection develop postoperative pain with detrimental effects on quality of life that also contributes to neuropathic and chronic postoperative pain.

Objective

To investigate the association of continuous local anesthetic wound infusion with pain management after head and neck surgery.

Design, Setting, and Participants

This prospective, longitudinal, nonrandomized clinical study carried out in a single tertiary referral center (December 1, 2015, to July 1, 2017) included 2 groups of 30 patients. Patients were consecutively enrolled and presented for ablative head and neck surgery including selective neck dissection and studied from the preoperative through the fourth postoperative day.

Interventions

The control group was treated according to a standardized escalating oral treatment protocol (ibuprofen, metamizole, opioids). The intervention group was treated with an intraoperatively applied pain catheter (InfiltraLong plus FuserPump, Pajunk, ropivacaine, 0.2%, 3 mL/h) that was removed 72 hours after operating.

Main Outcomes and Measures

Average and maximum pain intensities on a numeric rating scale; quality of life using the acute version of the validated 36-Item Short Form Survey; and neuropathic pain using the validated 12-Item painDETECT questionnaire. Consumption of opioid and nonopioid analgesics and evaluation of catheter-associated complications.

Results

During postoperative days 1 through 4, patients of the intervention group (mean [SD] age, 63.2 [13.3 years; 9 [30%] women) experienced lower mean (SD) (1.6 [1.4] vs 2.7 [1.8]; η2p = 0.09 [0.01-0.21]) and maximum (2.4 [2.2] vs 4.2 [2.0]; η2p = 0.11 [0.01-0.24]) pain intensities compared with the control group (mean [SD] age, 62.5 [13.6] years; 5 [17%] women). The intervention group also reported less neuropathic pain (mean [SD], 5.4 [3.4] vs 7.6 [5.1]; η2p = 0.09 [0.004 – 0.22]) and higher quality of life regarding vitality (56.2 [21.5] vs 43.8 [20.9], r = 0.29; 95% CI, 0.01-0.52) and pain (66.8 [27.3] vs 49.5  [27.7], r = 0.31; 95% CI, 0.04-0.54). Patients from the intervention group requested nonopioid analgesics considerably less often (n = 17 [57% ]vs n = 29 [97%]; ϕ = 0.47; 95% CI, 0.30-0.67) associated with a noticeably lower need to escalate pain treatment (n = 3 [10%] vs n = 9 [30%]; mean [SD] ibuprofen dose: 500 [173] mg vs 1133 [650] mg; r = 0.64; 95% CI, 0.02-0.91). No catheter-associated complications were observed.

Conclusions and Relevance

Continuous anesthetic wound infusion is associated with reduced postoperative pain and decreased demand for analgesics. It therefore expands the treatment options for postoperative pain in head and neck cancer.

Trial Registration

German Clinical Trials Register: DRKS00009378

Introduction

Malignant head and neck tumors are the sixth most common newly diagnosed malignant cancers worldwide, with increasing incidence.1 Besides tumor resection, appropriate neck dissection (ND) is an essential part of surgical therapy. Following ND, up to 80% of patients with head and neck cancer (HNC) experience acute pain, and more than 50% report pain scores greater than 3 during the first 24 hours after surgery, with a considerable reduction in their quality of life (QoL), despite the preservation of neuronal structures.2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19 Moreover, insufficient treatment of acute nociceptive pain contributes to neuropathic and chronic pain, which has been reported to occur in about 60% of the patients undergoing ND.4,9,15,20 Other than oral or intravenous analgesic medication,11,21 various supplemental approaches to reduce postoperative pain have been attempted.11,22,23,24,25,26,27 However, no standardized, optimal treatment of postoperative pain after ND has been established so far.28 Intraoperative application of pain catheters has been shown to significantly reduce postoperative pain in various surgical procedures.28,29,30,31,32,33,34,35 We therefore investigated the efficacy of continuous wound infusion (CWI) with a local anesthetic via a pain catheter for postoperative pain management after ND. We hypothesize that postoperative CWI leads to a reduction in pain sensation, alongside beneficial effects on QoL and the neuropathic pain components, and a reduced analgesic score—without increased treatment-related adverse effects. To our knowledge, this is the first study to apply CWI to this special patient cohort, comparing it with an orally administered standardized escalating treatment protocol.

Methods

Patient Data

This clinical study was conducted according to the Declaration of Helsinki, approved by the Ethics Committee of the University of Cologne, and registered in the German Clinical Trials Register (application number: DRKS00009378). The trial protocol is available in Supplement 1 and a TREND statement in Supplement 2. Overall, 60 patients were enrolled who were treated for HNC including ND from December 1, 2015, to July 1, 2017, at the Department of Otorhinolaryngology—Head and Neck Surgery, University of Cologne, Germany. Each patient gave written informed consent. Inclusion criteria were as follows: histologically confirmed HNC with tumor resection and/or unilateral or bilateral ND performed simultaneously, no bone resections, no neoadjuvant therapy, age 18 years or older, American Society of Anesthesiologists (ASA) statuses 1 to 3,36 and a body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) of 18.5 or higher. The following exclusion criteria were applied: age younger than 18 years, applied neoadjuvant therapy, refusal to participate in the study, known allergies/insensitivities to ropivacaine and/or amide-type local anesthetics, and a medical history of chronic pain and/or central nervous system disease. First, 30 consecutive patients were treated according to a standardized escalating pain treatment protocol, referred to as the control group. The subsequent 30 consecutive patients were implanted with a CWI pain catheter, referred to as the intervention group. Three additional patients were screened (1 from the protocol and 2 from the intervention group) but refused to participate and were therefore excluded. Average and maximum pain intensities (numeric rating scale [NRS], 0 = no pain; 10 = worst pain imaginable) were defined as primary study end points. Secondary end points comprised neuropathic pain, QoL, pain tolerance, analgesic score, and treatment-related adverse effects (Figure 1).

Figure 1. Study Protocol.

Figure 1.

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Of 60 patients, the first 30 consecutive patients were treated for postoperative pain according to the standardized pain relief concept only. Subsequently, the following 30 patients received a continuous wound infusion catheter at the end of surgery for postoperative pain treatment.

Patients’ clinical and surgical reports were searched for tumor characteristics (American Joint Committee on Cancer [AJCC] TNM Staging System 7th Edition, 2010) and performed surgical procedures. All NDs were performed as selective ND preserving the accessory nerve, the sternocleidomastoid muscle, the internal jugular vein, and the cervical plexus. The German guideline for the treatment of acute perioperative and posttraumatic pain considers all the performed surgical procedures to be associated with high postoperative pain levels.37

General anesthesia was induced with propofol (2-3 mg/kg body weight) and fentanyl (2-3 μg/kg body weight). Atracurium (0.5 mg/kg body weight) was used for neuromuscular relaxation. Anesthesia was maintained with sevoflurane (1.7-2.0 vol %) in an air-oxygen mixture and additional fentanyl (1 μg/kg body weight) as required. Pain levels in the recovery room were titrated to NRS lower than 3 by intravenous (IV) administration of piritramide (0.05 mg/kg body weight).

Postoperative Pain Treatment

The standardized pain treatment protocol consists of 3 escalating levels and rescue medication according to the guidelines of the World Health Organization (WHO),38 and was administered based on the patients´ reported pain intensities (NRS, 0-10) (Figure 2).

Figure 2. Standardized Escalating Pain Treatment Protocol Representing the 3 Escalating Levels of Medication.

Figure 2.

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The multiholed CWI catheter (InfiltraLong plus FuserPump, Pajunk GmbH) consists of an elastomeric pump filled with 250 mL of 0.2% ropivacaine connected to a flow-limiting valve (3 mL/h). Ropivacaine is a well-established long-acting amide local anesthetic, which has been proven to treat postoperative pain effectively in several surgical disciplines.39,40 Following ND, the catheter was placed adjacent to the cervical plexus underneath the internal jugular vein (IJV), left in place for 72 hours and removed in a similar way to the Redon drainage (eFigure 1 in Supplement 3). In simultaneous bilateral neck dissection, the catheter was implanted on either side. The simultaneously placed Redon drainage, removed on postoperative day 2, was placed on the IJV in between the sternocleidomastoid muscle, thus avoiding close contact to the catheter. Postoperatively, the neck was inspected daily for signs of infection and paralysis of the accessory nerve. Patients with CWI received additional oral analgesics according to the standardized pain treatment protocol in case of pain (NRS, >3 at rest or >5 on ambulation).

The medical staff of the acute pain service visited all patients twice daily during their inpatient stay. Patients were surveyed using a standardized hospital-internal protocol that evaluated their average and maximum pain intensities (NRS, 0-10), pain tolerance (NRS, 1 = no pain −4 = pain unbearable), and typical treatment-related adverse effects, ie, nausea, vomiting, obstipation, fatigue, concentration disorders, sleep disturbance, and vertigo (NRS, 0 = nonexistent −10 = strongest imaginable).

All patients were screened for a neuropathic pain component using the validated 12-item painDETECT questionnaire (PD-Q) (Pfizer Germany) on POD 2 and 4. All given answers were added up to provide the individual overall score that determines a negative (0-12), indeterminate (13-18), or positive (19-38) screening result.41,42

The health-related QoL was assessed preoperatively and on POD 4 using the acute version of the validated 36-Item Short Form Survey (SF-36, version 2.0: 1996). This consists of 8 domains that are valued with equally weighted scales ranging from 0 to 100,43 and results in a somatic and psychological total score. Higher scores correspond to lower levels of health-related impairments.

Statistical Analysis

Continuous variables were tested for normal distribution using the Kolmogorov-Smirnov test and each variable’s histogram. Differences in demographic data between the protocol and the intervention group were tested using cross tables (χ2 or Fisher exact test) for nominal data, unpaired t tests for continuous data (if normally distributed), and the Mann-Whitney U test for continuous, but not normally distributed or ordinal variables. The continuous variables are reported as mean (SD) values if normally distributed, or median (min-max) if not normally distributed or ordinal scaled. Nominal data are presented as No (%).

If the assumptions for parametric testing were met, differences in clinical outcomes between groups and across time were analyzed using mixed-model analysis of variance (ANOVA) with the within-subjects factor being postoperative days 1,2,3, and 4, and the between-factor group being the intervention vs the control group. This resulted in the 2 main effects postoperative day and group and the interaction postoperative day × group. In case of a significant interaction, the main effects were not investigated further.44 For interpretation of the interaction, follow-up repeated-measures ANOVA with the within-factor postoperative day were performed for each group. Differences between groups at each postoperative day were analyzed via independent t tests. In case of nonsignificant interaction, the main effects postoperative day and group were further investigated. A 2-way ANOVA tested the between-group interaction group × ND location, with independent t tests for post hoc analyses.

If the assumptions for parametric testing were not met, group differences on each postoperative day were tested with the Mann-Whitney U test. In general, the alpha level was adjusted for multiple comparisons in terms of Bonferroni correction during data analysis.

Effect sizes with 95% CIs are provided for each effect: η2p is reported on ANOVA model (0.01 = small, 0.06 = medium, 0.14 = strong effects44). For t tests and Mann-Whitney U tests, effect sizes are provided via r (with r = 0.1 = small, 0.3 = medium, 0.5 = strong effects44). Effect sizes for χ2 tests are reported as phi in case of nominal variables with 2 levels, or Cramer’s V in case of variables with 3 or more levels. A Cramer V as well as a ϕ of 0.1 displays a small effect, 0.3 = a medium, and 0.5 = a strong effect.

Due to the short follow-up there was only a limited number of missing values, which were equally distributed across groups. No values were missing in the primary end points (average and maximum pain scores). Statistical analyses were performed with SPSS statistical software (IBM SPSS Statistics 25.0; IBM) and R (https://www.r-project.org, version R.4.0.3, packages used: rcompanion for the calculation of 95% CI of cramer’s V and phi; MBESS for the calculation of the 95% CI of η2p [the repeated measures design was considered during calculation]).45,46

The sample size estimation was based on 2 similarly designed studies, in which CWI resulted in reduced averaged pain scores with strong effects for the first (effect size r = 0.85), second (r = 0.44), and third (r = 0.90) postoperative day.47,48 To calculate conservatively, we expected medium effect sizes (r = 0.3) in this study. Given an alpha of 0.05, a beta of 0.2, a medium effect size of r = 0.3 and a correlation among repeated measures of 0.5, a sample size calculation for our targeted effect (interaction: group [intervention, control group] × postoperative day [1,2,3,4] of the mixed-model ANOVA) revealed a required group size of at least 12 patients per group. Still, with 12 patients per group, normal distribution of the tested variables was not likely. Therefore, a study population of N = 30 per group was chosen. Based on the above-defined parameters (α = 0.05, β = 0.2 and a correlation of 0.5 among repeated measures), the targeted study population would enable us to find effects of r ≥ 0.15, equaling small- to medium-sized effects. Sample size estimation was conducted with G*Power (v.3.1.9.4, Heinrich-Heine-University).49

Results

The Table presents patients’ baseline demographic and clinical characteristic. Statistical computation revealed no meaningful differences between both study groups. The effective sample size was 26 patients per group for the complete data set and 30 patients per group for the primary end points (maximum and average pain score).

Table. Demographic, Clinical, and Surgical Characteristics of All Patients Included.

Characteristic Group, No. (%) Statistical comparison, effect size (95% CI)
Control (n = 30) Intervention (n = 30)
Age, mean (SD), y 62.5 (13.6) 63.8 (13.1) r = 0.04 (−0.21 to −0.30)
Male sex 25 (83) 21 (70) ϕ = 0.16 (−0.10 to 0.41)
ASA physical status Cramer V = 0.19 (−0.114 to 0.372)
I 6 (20) 3 (10)
II 18 (60) 14 (47)
III 6 (20) 13 (43)
Stated current consumption
Alcohola 27 (90) 27 (90) ϕ = 0b
Nicotine 8 (27) 4 (13) ϕ = 0.17 (−0.07 to 0.42)
Consumed pack-years, mean (SD) y 22.3 (19.9) 19.9 (19.4) r = 0.06 (−0.20 to 0.32)
Diagnosis
Diabetes mellitus type 2 3 (10) 6 (20) ϕ = −0.14 (−0.40 to 0.08)
Arterial hypertension (≥130/80 mm Hg50) 14 (47) 15 (50) ϕ = −0.03 (−0.28 to 0.21)
BMI, mean (SD) 24.3 (4.3) 26.5 (4.1) r = 0.25 (0.01 to 0.48)
Postoperative administration to ICU 12 (40) 14 (47) ϕ = −0.07 (−0.31 to 0.20)
Duration of postoperative administration to ICU, h 20.8 (34.37) 20.8 (37.72) r = 0.01 (−0.259 to 0.259)
ND Cramer V = 0b
Left-sided 13 (43) 14 (47)
Right-sided 15 (50) 14 (47)
Bilateral 2 (7) 2 (7)
ND levels
2 5 (17) 0 (0)
3 4 (13) 2 (7)
4 8 (27) 12 (40)
5 11 (37) 14 (47)
≥6 2 (7) 2 (7)
ND with no simultaneous ablative surgery 8 (27) 7 (23) ϕ = 0.04(−0.21 to 0.29)
Partial resection
Pharyngeal 2 (7) 3 (10) ϕ = −0.60b
Pharyngeal with microvascular reconstruction 5 (17) 5 (17) ϕ = 0 (−0.25 to 0.25)
Total parotidectomy 11 (37) 11 (37) ϕ = 0 (−0.26 to 0.25)
Partial laryngeal resection 2 (7) 2 (7) ϕ = 0b
Total laryngectomy 2 (7) 2 (7) ϕ = 0b
Tumor stages ≥T3 14 (47) 13 (43) ϕ = 0.03 (−0.23 to 0.27)
Intraoperative fentanyl, mg 0.6 (0.2) 0.5 (0.2) r = 0.30 (0.01 to 0.54)
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Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); ICU, intensive care unit; ND, neck dissection.

a

Defined as up to 1 drink per day for women and up to 2 drinks per day for men.

b

95% CI could not be calculated.

In terms of average pain, patients in the intervention group reported permanently less pain compared to patients in the control group, which was associated with a medium effect size across all postoperative days (η2p = 0.077; 95% CI, 0.01-0.14; Figure 3). The efficacy of the pain catheter was most evident on the first day displayed by a strong effect on the first postoperative day (mean [SD] NRS: 1.1 [1.7] vs 3.3 [2.6]; r = 0.46; 95% CI, 0.21-0.66) and followed by medium effect on postoperative day 2 (mean [SD] NRS: 1.9 [2.1] vs 3.4 [2.4]; r = 0.28; 95% CI, 0.03-0.51).

Figure 3. Average Pain Intensities on Postoperative Days 1 to 4 Comparing the Intervention Group With the Control Group.

Figure 3.

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Data presented as average value of all patients included. NRS indicates numeric rating scale.

The effect of CWI related to the reported maximum pain sensations across all postoperative days was comparable (η2p = 0.07; 95% CI, 0.01-0.14): CWI was most effective on postoperative day 1 (mean [SD] NRS: 1.9 [2.4] vs 4.7 [2.7]; r = 0.42; 95% CI, 0.26-0.66) and postoperative day 2 (mean [SD] NRS: 2.8 [2.4] vs 5.1 [2.4]; r = 0.44; 95% CI, 0.20-0.63) and subsequently decreased to the level of a still medium effect on postoperative day 3 (mean [SD] NRS: 2.5 [2.2] vs 3.6 [2.1]; r = 0.25; 95% CI, −0.01 to 0.48]) and postoperative day 4 (mean [SD] NRS: 2.4 [1.8] vs 3.6 [2.3]; r = 0.27; 95% CI, 0.01-0.49; Figure 4).

Figure 4. Maximum Pain Intensities on Postoperative Days 1 to 4 Comparing the Intervention Group With the Control Group.

Figure 4.

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Data presented as average value of all patients included. NRS indicates numeric rating scale.

The location, ie, right or left sided, of the performed ND did not affect the generally low average and maximum pain perceptions (when averaged across postoperative days 1-4) of both treatment groups (η2p ≤ 0.02; 95% CI, 0.00-0.09) differently. In this context, CWI greatly reduced the average pain sensation of patients of the intervention group (mean [SD] NRS, 1.6 [1.4]) compared with patients in the control group (mean [SD] NRS: 2.7 [1.7]; η2p = 0.09; 95% CI, 0.01-0.21; tested via the main effect group). Likewise, application of the pain catheter in the intervention group was associated with strongly reduced maximum pain levels (mean [SD] NRS, 2.4 [1.8]) compared with the control group (mean [SD] NRS: 4.2 [2.0]; η2p = 0.11; 95% CI, 0.01-0.23).

The performed ND, ie, bilateral or unilateral ND, considerably influenced the reported average pain sensations (main effect ND location: η2p = 0.32; 95% CI, 0.11-0.46). Bilateral ND caused substantially higher average pain sensations (mean [SD] NRS, 5.4 [0.9]) compared with single-sided ND, ie, left (mean [SD] NRS, 1.8 [1.5]; r = 0.67; 95% CI, 0.40-0.83) and right ND (mean [SD] NRS, 2.1 [1.5]; r = 0.62; 95% CI, 0.34-0.80).

With regard to maximum pain levels (main effect ND location, η2p = 0.23; 95% CI, 0.05-0.38]), bilateral ND (mean [SD] NRS, 6.7 [1.5]) was reported to be far more painful than left-sided (mean [SD] NRS: 3.1 [2.2]; r = 0.51; 95% CI, 0.18-0.74) and right-sided ND (mean [SD] NRS: 3.1 [1.8]; r = 0.57; 95% CI, 0.27-0.77).

Screening for the neuropathic pain component revealed that the quality of pain was only moderately increased in the control group compared with the intervention group (mean [SD] NRS: 7.6 [5.1] vs 5.4 [3.4], η2p = 0.09; 95% CI, 0.004-0.22) and did not change differently in both groups during the postoperative days surveyed (η2p = 0.02; 95% CI, 0.00-0.12).

Patients of the intervention group consistently rated their pain tolerance more positively than the control group, with patients of the intervention group reporting a median rating of 1 (equaling “no pain”) and the control group of 2 (“well tolerable pain levels”) on most postoperative days, with strong effect sizes on the first and second postoperative days and moderate effect sizes on postoperative days 3 and 4 (postoperative day 1: NRS: 1 [range, 1-4] vs 2 [range, 1-4], r = 0.48; 95% CI, 0.24-0.69; postoperative day 2: NRS: 2 [range, 1-3] vs 2 [range, 1-3], r = 0.44; 95% CI, 0.22-0.63; postoperative day 3: NRS: 1 [range, 1-4] vs 2 [range, 1-4], r = 0.28; 95% CI, 0.05-0.53; postoperative day 4: NRS: 1 [range, 1-3] vs 2 [range, 1-4]; r = 0.30; 95% CI, 0.05-0.53).

In general, the favorable pain sensations reported by patients treated with CWI were associated with a distinctly reduced number of patients that demanded for nonopioid analgesics (n = 17, 57% vs n = 29, 97%; ϕ = 0.47; 95% CI, 0.30-0.67) and markedly reduced need to escalate pain treatment to level 2 characterized by the administration of ibuprofen (n = 3 [10%], mean [SD] 500 [173] mg vs n = 9 [30%], mean [SD] 1133 [650] mg; r = 0.64; 95% CI, 0.02-0.91; eTable 1 in Supplement 3). However, CWI did not affect the average consumption of level 1 medication, ie, metamizole, of all surveyed patients (mean [SD] 1553 [675] mg vs 1492 [954] mg; r = 0.04; 95% CI, −0.32 to 0.38; eTable 1 in Supplement 3).

Overall opioid consumption was low, with only few patients (1 [3%] in the intervention group and 4 [13%] in the control group) needing opioids, which was independent of treatment group (ϕ = 0.18 [–]).

Concerning therapy-related adverse effects, the results show that the applied pain therapy affected both groups to the same extent (eTable 2 in Supplement 3). However, clearly more patients without CWI (26 vs 19; ϕ = 0.27; 95% CI, 0.05-0.54) reported a moderately increased disturbance of their ability to concentrate (mean [SD] NRS: 2.0 [1.5] vs 0.9 [1.3]; r = 0.35; 95% CI, 0.09-0.55; eTable 2 in Supplement 3).

The QoL assessed in the short postoperative period considered was based on the psychological and somatic parent scores of the SF-36 questionnaire43 before and after the treatment that showed no association with the CWI treatment (η2p ≤ 0.06; 95% CI, 0.00-0.19; eFigure 3 in Supplement 3). Of all the subscores, only vitality (η2p = 0.12; 95% CI, 0.02-0.26) and pain (η2p = 0.15; 95% CI, 0.03-0.29; eFigure 3 in Supplement 3) revealed a distinct association with the intervention. Preoperatively, there were no differences between groups (mean [SD] vitality score: 67.4 [17.8] vs 63.7 [26.2]; r = 0.09; 95% CI, −0.20 to 0.36; mean [SD] pain score: 88.3 [22.0] vs 80.2 [27.6]; r = 0.02; 95% CI, −0.26 to 0.29) and, as expected, both subscores decreased postoperatively. However, both scores were moderately higher in the intervention group (mean [SD] vitality score: 56.2 [21.5] vs 43.8 [20.9]; r = 0.29; 95% CI, 0.01-0.52; mean [SD] pain score: 66.8 [27.3] vs 49.5 [27.7]; r = 0.31; 95% CI, 0.04-0.54; eTable 3 in Supplement 3) postoperatively, corresponding to a noticeable lower level of impairment.

No catheter-related complications were observed postoperatively, ie, symptoms of local or systemic ropivacaine intoxication or paralysis of the preserved accessory nerve. There was no partial or total failure of the catheter system and the pump did not impair patients’ mobilization postoperatively.

Discussion

This study demonstrates that CWI is associated with decreased average and maximum pain intensities during the immediate postoperative period after head and neck surgery. Furthermore, patients with CWI reported favorable pain tolerance, less trouble concentrating, and a higher vitality score. Application of CWI was markedly associated with a decreased number of patients demanding nonopioid analgesics and reduced need for escalation of treatment.

The combination of regional anesthetic techniques and systemic pain treatment has been associated with significantly reduced postoperative pain levels, reduced opioid consumption and adverse effects, higher patient satisfaction, and shorter inpatient stays in various surgical fields.51,52,53,54,55,56

However, the effects of CWI for patients undergoing major ablative head and neck surgery have until now received only limited attention. Our study is in line with Charous et al,48 who investigated pain catheter application in 28 patients following thyroid or parotid surgery. The patients reported significantly less pain on the first POD, consumed significantly less opioid analgesics, experienced less nausea and vomiting, and did not suffer any catheter-related complications. Moreover, no local or systemic intoxications caused by local anesthetics have been reported so far. Even in cases of increased ropivacaine dosages, systemic blood levels remain far below toxic effects thresholds, and due to its slow infusion rate ropivacaine seems to be totally absorbed locally.57,58 There have been no reports of increased wound infection rates compared with placebo or control groups without catheters.59 This reaffirms our experience of CWI as an easy to handle, safe, and effective procedure.

Apart from the immediate analgesic effect, there is evidence that effective perioperative and postoperative anesthetic treatment positively influences patients’ long-term outcomes, especially in patients with cancer.60,61 Continuous wound infusion may reduce spinal dorsal horn sensitization and even block parietal afferents, which can lead to long-lasting pain reduction, as well as a reduced inflammatory reaction and consequently better perfusion and oxygenation of the wound margins.62,63 Most interestingly, in vivo and vitro experiments have demonstrated that local anesthetics may inhibit the proliferation and migration of tumor cells, as well as induce apoptosis, which dampens immunosuppression and enhances systemic anti-inflammatory action.60,61,64,65 Cassinello et al66 consider that using local anesthetics in patients with cancer might even support recurrence-free survival.

Limitations

The foremost limitation of this study is the lack of randomization of patients and blinding of treatment. Still, both patient groups were comparable regarding demographic, surgical, and oncologic data. Furthermore, we cannot completely exclude a bias caused by a placebo effect of the implanted catheter. One should also be aware of psychological factors that positively influence postoperative pain, such as preoperative counseling on postoperative pain treatment52,55; all patients were extensively informed about the scope and the implementation of the postoperative analgesic treatment. It should be noted that the pain catheter may block pain perception transmitted via the cervical plexus but not related to other cranial nerves. However, surgical sites away from the neck, such as the harvest of a radial forearm flap, were equally distributed, and patients were asked to report pain levels that refer to the cervical surgical site. The same applies to total parotidectomies, which do not cause high levels of postoperative pain unless performed simultaneously with a neck dissection.37 We also did not investigate cost-effectiveness because this was beyond the scope of this study. However, several studies have reported that CWI is more effective and less costly compared with commonly used analgesic techniques.67 Given the short postoperative survey period, the assessment of the general health status measure of the SF-36 may not absolutely correspond to surgery-specific health factors. Furthermore, the preoperative health status was assessed before surgery, but after the patients had decided to undergo surgery. This may have influenced the preoperative results and the subsequent observed differences. Early posttreatment pain strongly influences any pain experienced in the 2 years following surgery.4 The presented beneficial impact on the reduction of acute nociceptive and neuropathic postoperative pain therefore encourages optimism for a corresponding positive long-term effect, yet to be determined in future studies.

Conclusions

Continuous wound infusion with ropivacaine can be advocated as a safe method that is associated with reduced postoperative pain following head and neck surgery. It also allows for reduced consumption of systemic analgesics and uncomplicated handling, and is not linked to any catheter-related complications. Thus, CWI should receive consideration as part of a multimodal postoperative analgesic concept in patients with head and neck diseases. These positive first results on CWI should be confirmed in larger studies.

Supplement 1.

Trial Protocol

Click here for additional data file. (310.1KB, pdf)
Supplement 2.

TREND Statement

Click here for additional data file. (417.6KB, pdf)
Supplement 3.

eFigure 1. Intraoperative Positioning of the Pain Catheter on the Left Side of the Neck Before Wound Closure

eFigure 2. Neuropathic Pain Sensation Reported on POD 2 and 4, and the Calculated Average Levels

eTable 1. Consumption of Non-Opioid and Opioid Analgesics

eTable 2. Surveyed Treatment-Related Side Effects

eTable 3. Somatic and Psychological Scores and Subscores of the SF-36 Questionnaire

eFigure 3. Somatic and Psychological Scores Derived From the Survey Using the SF-36

Click here for additional data file. (336.3KB, pdf)
Supplement 4.

Data Sharing Statement

Click here for additional data file. (22.2KB, pdf)

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplement 1.

Trial Protocol

Click here for additional data file. (310.1KB, pdf)
Supplement 2.

TREND Statement

Click here for additional data file. (417.6KB, pdf)
Supplement 3.

eFigure 1. Intraoperative Positioning of the Pain Catheter on the Left Side of the Neck Before Wound Closure

eFigure 2. Neuropathic Pain Sensation Reported on POD 2 and 4, and the Calculated Average Levels

eTable 1. Consumption of Non-Opioid and Opioid Analgesics

eTable 2. Surveyed Treatment-Related Side Effects

eTable 3. Somatic and Psychological Scores and Subscores of the SF-36 Questionnaire

eFigure 3. Somatic and Psychological Scores Derived From the Survey Using the SF-36

Click here for additional data file. (336.3KB, pdf)
Supplement 4.

Data Sharing Statement

Click here for additional data file. (22.2KB, pdf)

Articles from JAMA Otolaryngology-- Head & Neck Surgery are provided here courtesy of American Medical Association

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