|Year : 2020 | Volume
| Issue : 2 | Page : 205-210
The effect of local wound infiltration vs caudal block on wound infection and healing after inguinal herniotomy in pediatrics − a double-blinded randomized study
Mohammad H.I Ahmad Sabry, Ramadan A Ammar, Rana Bakr
Department of Anesthesiology and Surgical Intensive Care, Faculty of Medicine, Alexandria University, Alexandria, Egypt
|Date of Submission||12-Jun-2019|
|Date of Acceptance||15-Jan-2020|
|Date of Web Publication||27-Jun-2020|
MBChB, MSc, FRCPC, MD, ABPM Mohammad H.I Ahmad Sabry
Department of Anesthesiology and Surgical Intensive Care, Alexandria Faculty of Medicine, Khartoum Square, Shalalat, Alexandria 2111
Source of Support: None, Conflict of Interest: None
Purpose The aim was to compare the use of local wound infiltration (LWI) vs caudal block (CB) on wound infection and healing after inguinal herniotomy in pediatrics.
Patients and methods A total of 50 patients were assigned randomly into two groups (n=25/group) that received LWI using up to 1 mg/kg bupivacaine 0.25% or CB in group C using 1 mg/kg bupivacaine 0.25%. The authors measured wound infection and healing (primary outcome) using Southampton scoring system and postoperative analgesia (secondary outcome) using Faces Legs Activity Cry Consolability tool scale.
Results There was a statistically significant difference regarding Southampton scoring system between the two studied groups, with higher number of patients with higher scores in group L (P=0.008). Comparison between the two groups according to preoperative and postoperative white blood cell count shows statistically significant increase in group C on day 7 postoperatively (P=0.015). There was a statistically significant decrease in pain score scale in group C compared with group L at 15 min (P=0.035), 60 min (P=0.007), and 3 h postoperatively (P=0.049). Analgesic requirement shows a statistically significant increase in group L at 15 and 60 min postoperatively (P=0.022). Postoperative complication was not statistically significant (P=1.000).
Conclusion LWI is a safe and satisfactory analgesia option for surgery, and compared with CB, it is not overwhelming. CB provides better and longer analgesia; however, complications are more common. Wound healing was found to be better with CB, but it was clinically insignificant, as all patients healed normally. LWI did not cause wound infection in any of the patients included in the study and showed decrease in white blood cells in group L on day 7 postoperatively.
Keywords: bupivacaine, caudal, hernioraphy, local infiltration, wound healing
|How to cite this article:|
Ahmad Sabry MH, Ammar RA, Bakr R. The effect of local wound infiltration vs caudal block on wound infection and healing after inguinal herniotomy in pediatrics − a double-blinded randomized study. Res Opin Anesth Intensive Care 2020;7:205-10
|How to cite this URL:|
Ahmad Sabry MH, Ammar RA, Bakr R. The effect of local wound infiltration vs caudal block on wound infection and healing after inguinal herniotomy in pediatrics − a double-blinded randomized study. Res Opin Anesth Intensive Care [serial online] 2020 [cited 2020 Oct 28];7:205-10. Available from: http://www.roaic.eg.net/text.asp?2020/7/2/205/287993
| Introduction|| |
Caudal block (CB) is a commonly used technique for herniotomy in pediatrics; however, local wound infiltration (LWI) offers an extensively used option for postoperative analgesia. Local anesthetic effect on wound healing is well known , with its antimicrobial or anti-inflammatory effect , This study aims to assess effect of LWI in comparison with CB by bupivacaine 0.25% after inguinal herniotomy in pediatrics on wound healing and infection, and also postoperative analgesia, analgesic requirements, and complications were measured.
| Patients and methods|| |
Approval of this study was obtained from the Alexandria Faculty of Medicine Ethics Committee, and the study was registered with clinicaltials.gov registry ID; NCT03563625. Sample size calculation was done by our statistic Department of Alexandria University Research Institute. Primary outcome was measured using χ2-test. Student’s t-test was used for white blood cells (WBCs) count. Mann–Whitney U-test was used for Faces Legs Activity Cry Consolability tool (FLACC) test. A prospective randomized clinical study included 50 infants aged 2 months to 1 year admitted to the Pediatrics Surgery Department of Alexandria University Hospitals for elective inguinal herniotomy surgery. All patients were class I or II according to American Society of Anesthesiologists classification. The patients were randomized using closed envelope into two groups using closed envelope technique, with 25 patients each:
- Group L: 25 patients received 1 mg/kg bupivacaine 0.25% (diluted as 1 ml bupivacaine+1 ml normal saline) by local infiltration in the wound before closure of the skin and subcutaneous.
- Group C: 25 patients received CB with 1 mg/kg bupivacaine 0.25%.
Patients with history of developmental delay or mental retardation, patients with diabetes mellitus, patients with known allergy or contraindication to any local anesthetics, patients with known congenital anomaly in the inguinal region, and any patient who developed any infections postoperatively (respiratory infection and urinary infection) other than wound infection were excluded.
All patients were evaluated by history taking from parents, clinical examination, and laboratory investigations. Explanation of the technique of postoperative analgesia to the parents and that the wound will be observed postoperatively for signs of inflammation and infection were done.
- Premedication: paracetamol suppository 40 mg/kg was given approximately half an hour before anticipated surgery.
- Anesthesia: all patients were monitored for the following:
- Heart rate (beats/min) through continuous ECG tracing (lead II).
- Non-invasive arterial blood pressure (mmHg).
- Arterial oxygen saturation using pulse oximetry (%).
- Induction of general anesthesia was achieved with up to 8% sevoflurane in 100% oxygen.
- After securing an IV line with cannula, all patients received fentanyl 1 µg/kg.
- Laryngeal mask airway of proper size was inserted under adequate depth of anesthesia.
- Anesthesia was maintained with sevoflurane with concentration maintaining adequate depth of anesthesia.
- At the end of the procedure and before stitches, bupivacaine 0.25% was infiltrated in the skin and subcutaneous layer in group L, and CB was performed in group C. At the end of the surgery, inhalational anesthetic was stopped, and laryngeal mask was removed when patient was fully conscious.
- Postoperative pain was assessed using the FLACC, 0–10 at 15 min, 1 h, and 3 h after operation by an anesthesiologist blinded to the intervention done.
- A child with a score of more than 4 on FLACC received intravenous acetaminophen 15 mg/kg.
- The incision was monitored for signs of infection (redness, hotness, swelling, discharge, or separation/breakdown of deep tissues) obtained on day 7 postoperative or with sutures removal or any time before this if he/she develops any of wound inflammation signs earlier.
- Measurements included the following:
- Postoperative vital signs/h for 4 h.
- FLACC, 0–10 at 15 min, 1 h, and 3 h after operation.
- Timing of first postoperative complaint of pain, first requirement for postoperative analgesia, and total consumption of analgesia.
- Laboratory measurements: white blood cells count at day 0 and day 7 postoperative.
- Culture: with first dressing change at day 7 postoperative from the wounds with discharge (suspected infected wounds).
- Wound infection and healing scale: using Southampton scoring system , which classifies wounds according to healing into six grades (0, I, II, III, IV, and V) ([Table 1]) by a surgeon blinded to the intervention done.
| Results|| |
Data were fed and analyzed using IBM SPSS software package version 20.0. (IBM Corp., Armonk, New York, USA). Patients’ age ranged from 2 to 12 months, with a mean value of 7.14±3.86 months in group L and 5.64±3.92 months in group C. Patients comprised 18 (72%) males and seven (28%) females in group L and 22 (88%) males and three (12%) females in group C. In group L, the body weight ranged from 4 to 14 kg, with a mean value of 8.36±2.89 kg, and in group C, it ranged from 3.5 to 15 kg, with a mean value of 7.10±3.17 kg. Regarding residency, seven (28%) were from urban environment and 18 (72%) from rural environment in group L and seven (28%) from urban environment and 18 (72%) from rural environment in group C. There was no statistically significant difference between the two groups regarding demographics and residency.
There was a statistically significant decrease in pain score scale in group C compared with group L at 15 min (P=0.035), 60 min (P=0.007), and 3 h postoperatively (P=0.049) ([Figure 1]).
|Figure 1 Comparison between the different studied groups according to Faces Legs Activity Cry Consolability tool.|
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At 15 min, the FLACC score ranged from 0 to 4, with a mean value of 1.84±1.03 for group L, and ranged from 0 to 2, with a mean value of 1.16±0.85 for group C.
At 60 min, the FLACC score ranged from 0 to 6, with a mean value of 2.24±1.92 for group L, and ranged from 0 to 4, with a mean value of 0.88±1.24 for group C.
At 3 h postoperatively, FLACC score ranged from 0 to 4, with a mean value of 1.36±1.58 for group L, and ranged from 0 to 4, with a mean value of 0.64±1.25 for group C.
Analgesic requirement shows statistically significant increase in group L at 15 and 60 min postoperatively, with six patients in group L vs none in group C (P=0.022). Postoperative complication was not statistically significant, with five patients in group L vs one patient in group C (P=1.000).
There was a statistically significant difference regarding Southampton scoring system between the two studied groups with higher number of patients with higher scores in group L (P=0.008) ([Figure 2]).
|Figure 2 Comparison between the two studied groups according to Southampton score on day 7 postoperatively.|
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Scores for group L were as follows: seven (28.0%), zero (normal healing); nine (36.0%), IA (normal healing with some bruising); and nine (36.0%), IC (normal healing with mild erythema).
Scores for group C were as follows: 18 (72.0%), zero (normal healing); four (16.0%), IA (normal healing with some bruising); and three (12.0%), IC (normal healing with mild erythema).
Comparison between the two groups according to preoperative and postoperative white blood cell count shows statistically significant increase in group C at day 7 postoperatively, with mean white blood cell count of 9.98±1.26 in group L and 11.17±1.98 in group C (P=0.015) ([Figure 1],[Figure 2],[Figure 3]).
|Figure 3 Comparison between the different studied groups according to white blood cells.|
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One patient in the group C was complicated by intraoperative partial airway obstruction owing to laryngeal spasm and was intubated. Two patients had intraoperative tachycardia resolved by fluids (one patient in each group). There was no statistically significant between the two groups regarding intraoperative complication. There was no significant difference regarding hypotension or bradycardia.
Difference in the incidence of postoperative vomiting in the group L (n=2, 8%) and the group C (n=1, 4%), incidence of postoperative urine retention in group C (n=1, 4%) and in group L (n=0, 0%), and incidence of postoperative complication was not statistically significant (P=1.000).
| Discussion|| |
Regarding wound healing, all our cases were grades 0 or I, which represents normal healing using Southampton wound scoring system. There was a statistically significance between the 2 studied groups with higher number of patients with higher scores in group L, representing better healing in the caudal group. Southampton scoring system was used in our study to classify wound healing and surgical site infection, which is in agreement with Alam et al.  in their study on surgical site infection frequency after open cholecystectomy.
To our knowledge, this is the only study done on the effect of local anesthetic on healing in pediatric surgical wounds. There was an article on human done on venous leg ulcers treated topically before debridement with EMLA cream 5% (Eutechtic Mixture of Local Anaesthetic).
In spite of other studies done on surgical wounds in which the effect of LAs on healing was mentioned, wound healing was not their primary outcome or end point.
Moreover, this study showed less WBCs in LA group, which is the only study that commented on this.
In-vitro studies of cell types directly involved in wound healing reported the following: LAs in concentrations achieved with local infiltration clearly inhibit the activation, migration, and metabolic activity of inflammatory cells. These studies have been reviewed by Hollman and Durieux  and so was not considered here, except to note that the effect on wound healing may well vary with the type of wound. In general, inhibition of the inflammatory response should decrease secretion of chemoattractants and growth factors by inflammatory cells and slow down wound healing. This LA effect could increase infection of dirty traumatic wounds, but some sterile surgical wounds might benefit from a less robust inflammatory response: animals with Staphylococcal peritonitis had increased mortality with lidocaine , whereas those with chemical peritonitis had reduced extravasation with topical 1% lidocaine or 0.5% bupivacaine .
Most in-vitro studies of wound healing have modeled the second stage of wound healing, granulation/proliferation, assessing the viability, replication, metabolic activity, or protein secretion of fibroblasts and related cell types ,,,,,,.
The in vitro studies that have been published using cells of human origin all showed significant adverse effects with LA (different aminoesters and aminoamides LA) concentrations relevant to clinical use, although Pigeolet et al.  also reported an initial, but short-lived, stimulation of fibroblast proliferation and also tested the effect of procaine (aminoester LA) for up to 40 days. The other studies were limited to 48-h exposure to LA or less. Three studies varied exposure time and demonstrated time-dependent toxicity ,,. Two studies tested single doses of a given LA ,; all others found increasing toxicity with increasing LA concentrations in ranges clinically relevant to local infiltration.
Other in vitro studies using animal cells have been published . One study by Schultz and Lipton  reported minimal morphologic change after 90 min exposure to 0.06% bupivacaine. Another study reported significant adverse effects on viability, matrix secretion, cellular ultrastructure, or motility after exposure to low LA concentrations. Exposure times ranged from 30 min to 7 days. Sturrock and Nunn  in their study varied exposure times and found that toxicity increased with time. Studies varied LA concentrations and found toxicity to be dose dependent in ranges expected after local infiltration of LA.
In-vivo studies of LA effect on wound healing reported the following:
This study limits evaluation of the patients to 7 days postoperative. Almost all clinical studies of local infiltration have reported only general, subjective impressions of wound healing over a limited time; their focus has been the analgesic efficacy of wound infiltration. In a clinical study of persistent LA application, which had wound healing in adults as its end point by Hansson et al. , eight treatments of leg ulcers with EMLA cream over 6–8 weeks suggested an effect of decreased ulcer healing compared with control, although the difference was not statistically significant. However, our study was done on pediatric surgical wounds with difference in pathophysiology of wound healing. Fredman et al.  in a study of 24-h intermittent instillation of 0.2% ropivacaine concluded that ‘no delay in wound healing was noted in our study population,’ but reported only visual assessment of the wound within an unspecified time period, apparently 1–3 days, and a leukocyte count at 3 days. The time period, representative of most clinical studies, may have missed some early wound disruptions and incisional hernias that may manifest months or years after surgery.
Brower and Johnson  suggested that there is no established clinical syndrome related to LA effects on wound healing; conversely, there is not strong evidence from human studies that LA does not adversely affect wound healing.
Animal models have tested the effect of LA injection or topical application, on surgical wounds or corneal epithelium, using healing time, tensile strength, collagen synthesis, bone healing, infection, or inflammation as measures. All animal studies used rodents, whose skin wounds heal rapidly at near maximal rates  and thus may not be as susceptible to inhibitory agents as human wounds, particularly when systemic factors, which limit wound healing, are also present.
Regarding postoperative analgesia, postoperative pain was assessed using FLACC pain assessment scale that showed significant decrease in group C (CB) compared with group L (LAI). There are studies comparing CB vs LWI, but all of them include ilioinguinal, iliohypogastic nerve block, and local infiltration . We identified seven studies in total. Both interventions were performed after surgery in two studies like this study ,; however, the other four studies performed caudal preoperatively and infiltration postoperatively ,,,, and only one study performed both techniques preoperatively . All included hernia surgeries only except for Lafferty and colleagues (only orchidopexy) . All used bupivacaine in concentration of 0.25% for CB and 0.25–0.5% for LWI. The volume ranged from 0.7 to 1.0 ml/kg for CB and from 0.2 to 0.7 ml/kg for LWI. Only Conroy et al.  used epinephrine along with bupivacaine.
The efficiency of preincision vs postincision wound infiltration using lidocaine 1% on the postoperative pain of adult patients with inguinal herniotomy was compared by Ejlersen et al. . The demand for additional analgesics occurred earlier in those who received lidocaine infiltration after incision. The preincisional infiltration group also had fewer patients requiring supplemental analgesic, suggesting that the inhibition of peripheral sensitization may be of major importance in impeding the development of acute pain and explain why prevention is important in handling operative pain.
Spliter et al.  in agreement with this study compared local infiltration vs caudal in hernia repair in pediatrics, where LA group required more acetaminophen in the Day Care Surgical Unit. The incidence of vomiting and the times to first ambulation and first urination were similar. The LA patients had a shorter recovery room stay, as postoperative stay was prolonged in the CA group. They concluded that LA and CA have similar effects on postoperative care, with only slight differences.
There are several limitations to the present study, such as small sample size to discover some complication, for exmaple, wound infection. Moreover, we could not reach equal doses of LA in the two studied groups, as in L group the small size of wound limits the use of same dose of LA used in C group. Using postincisional LWI may also bias the study toward CB, as studies suggest better pain control with preincisional LWI. There is a lack of long-term postoperative follow-up to evaluate whether there are other late-onset complications.
| Conclusion|| |
LWI is a safe and satisfactory analgesia option for surgery, and compared with CB, it is not overwhelming. CB provides better and longer analgesia; however, complications are more common. Wound healing was found to be better with CB, but it was clinically insignificant, as all patients healed normally. LWI did not cause wound infection in any of the patients included in the study and showed decrease in WBCs in group L on day 7 postoperatively.
The work was carried out in Alexandria University Hospitals.
Clinical implications: (a) What is already known: LWI using local anesthetics may affect wound healing with possible antimicrobial effect. (b) What this article adds: local herniotomy wound infiltration in pediatrics using Bupivacaine affects wound healing, with no clinical significance in this study sample size, with lower white blood count in postoperative day 7 as possible antimicrobial effect compared with caudal anesthesia.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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