Outcomes During a Transition Period from Open to Laparoscopic Pyloromyotomy

Abstract

Background:

Previous studies suggest that laparosopic pyloromyotomy may have some benefits over an open approach. We examined our results during a transition period from open to laparoscopic pyloromyotomy to see whether these benefits are sustained during the learning curve.

Methods:

This is a retrospective case note review of all patients undergoing pyloromyotomy at a tertiary institution for a 5-year period (2010–2015). Data are presented as median (range). Statistical analysis was performed with Fisher's exact and Student's t-test.

Results:

A total of 185 pyloromyotomies were performed, with data available for 90 open and 60 laparoscopic procedures. Duration of surgery was 42 (16–102) minutes for open and 28 (14–97) minutes for laparoscopic procedures (P = .0001). Total paracetamol requirements were 23.5 (0–169.4) mg/kg for open and 13.9 (0–95.3) mg/kg for laparoscopic cases (P = .008). No postoperative analgesia was required for 23 open and 29 laparoscopic patients (P = .005). Complications in the open group included incomplete pyloromyotomy (n = 1) and wound infection (n = 4); complications in the laparoscopic group included incisional hernia (n = 1), omental port-site herniation (n = 2), and suspected perforation with conversion to open procedure, although no perforation was found (n = 1; P = 1.000).

Conclusion:

Our results suggest that when the laparoscopic technique is first introduced, overall complication rates are not statistically higher, and operative times and analgesia requirements are significantly shorter, despite the learning curve.

Introduction

Hypertrophic pyloric stenosis (HPS) is the most common surgical pathology in infants, affecting 1–3 per 1000 live births.¹ It is characterized by gastric outlet obstruction secondary to pyloric muscle hypertrophy, causing dehydration and electrolyte disturbance. Ramstedt² first described pyloromyotomy in 1912, utilizing a right upper quadrant incision to expose the pyloric tumor and incise the seromuscular layer longitudinally, leaving the mucosa intact. In 1986, Tan and Bianchi³ introduced a circumumbilical incision to improve cosmesis, followed in 1991 by Alain's⁴ use of a laparoscopic technique using three 5 mm ports.

Laparoscopic pyloromyotomy is now offered by some pediatric surgical centers either as an alternative to open surgery or as the technique of choice.⁵ There is evidence that laparoscopic pyloromyotomy has a shorter operative time than open pyloromyotomy^6,7 with decreased surgical stress⁸ and improved cosmesis.^4,6,9 Statistically significant shorter hospital stay and time to full feeds have also been demonstrated.^6,10 Low complication rates are quoted for either technique.¹¹ One of the main concerns with laparoscopic pyloromyotomy is the possibility of increased complications, particularly incomplete pyloromyotomy, during the learning curve.^11,12 The first laparoscopic pyloromyotomy was performed at our institution in December 2011, and by June 2014, it had replaced open pyloromyotomy as the technique of choice.

Methods

Inclusion criteria

Data were collected retrospectively from all patients who underwent open or laparoscopic pyloromyotomy at our tertiary institution for a 5-year period (July 2010–July 2015). All patients had a clinical diagnosis of HPS, confirmed on abdominal ultrasound scan (pyloric single wall thickness >4 mm and pyloric length >16 mm). All received intravenous fluid resuscitation to correct biochemical abnormalities before theater.

Surgical technique

The open technique used a circumumbilical incision as described by Tan and Bianchi.³ The laparoscopic technique used a 5 mm primary port and two stab incisions to introduce 3 mm instruments, as described by Bufo.¹³ A grasper through the right flank incision stabilized the duodenum distal to the pylorus, whereas a retractable endotome through the left flank incision allowed incision of the seromuscular layer. A 3 mm pyloric spreader was used to complete the pyloromyotomy.¹⁴ The myotomy was considered adequate when both edges could be moved independently. Prophylactic antibiotics were not given to any patient.

Analgesia protocol

All patients received either rectus sheath or transversus abdominis plane block performed by the anesthetist after induction of general anesthesia. Intraoperative paracetamol was given at a dose of 15 mg/kg at the anesthetist's discretion. Postoperative pain was assessed by nursing staff using the face, legs, activity, cry, consolability (FLACC) score¹⁵ and paracetamol was given at 10–15 mg/kg as required. Additional analgesia included doses of ibuprofen at 5 mg/kg or Oramorph at 100 μg/kg.

Postoperative feeding

Until April 2014, a feeding protocol was used (Table 1). After this time, ad libitum feeding was introduced.¹⁶ The child was discharged after tolerating two full feeds.

Table 1.

Feeding Protocol Used Until April 2014

Timing	Volume	Type of feed
First 12 postoperative hours	Nil by mouth	—
Three-hourly feeds
Feeds 1 and 2	Half requirement	Dioralyte™ (Sanofi, Surrey, England)
Feeds 3 and 4	Full requirement	50% Dioralyte, 50% milk
Feeds 5 and 6	Full requirement	Milk

Data collection

Retrospective data collection was performed using case notes and operating room information system records. This included gestation, weight at presentation, duration of surgery, grade of operating surgeon, and supervision level of registrars. The postoperative outcomes were time to full feed, analgesia requirements, postoperative length of stay, and overall complications including conversion to open approach. The learning curve for the laparoscopic approach was examined by analyzing the data in four quarters, each representing 15 cases.

Data analysis was performed using two-tailed Fisher's exact test for categorical variables and paired Student's t-test for continuous variables, with P values shown in parentheses, and values <.05 considered statistically significant.

Results

From July 2010 to July 2015, 185 pyloromyotomies were performed, with full data available for 90 open and 60 laparoscopic cases. All results are shown as median (range).

Demographics

The two groups were homogenous. Gestation was 40 (34–42) weeks in both groups; weight was 3.83 (2.42–5.45) kg in the open group and 3.69 (2.38–5.90) kg in the laparoscopic group (P = .74).

Intraoperative details

Median duration of surgery was 42 (16–102) minutes for the open technique and 28 (14–97) minutes for the laparoscopic technique, which was statistically significant (P = .0001) (Table 2). Grade of operating surgeon was consultant in 31 cases and registrar in 59 cases in the open group, and consultant in 52 and registrar in 8 cases in the laparoscopic group (P = .0001). A consultant was present for 35 (38.9%) open and 57 (95%) laparoscopic cases (P = .0001).

Table 2.

Intraoperative Details

	Open group (n = 90)	Laparoscopic group (n = 60)	P
Duration of surgery (minutes)	42 (16–102)	28 (14–97)	.0001^a
Grade of operating surgeon (grade and no. of cases)	Consultant: 31 Registrar: 59	Consultant: 52 Registrar: 8	.0001^b
Consultant present (no. of cases)	35	57	.0001^b

Paired Student's t-test.

Fisher's exact test.

Learning curve for laparoscopic pyloromyotomy

The laparoscopic cases were divided into four quarters, each containing 15 cases. Although the median operative time did not significantly change, the maximum duration reduced with additional experience (the single case of negative conversion for suspected perforation has been excluded) (Fig. 1).

FIG. 1.

Operative time for laparoscopic cases (minutes)—presented in quarters.

There was no significant difference in postoperative complications/conversions during the four quarters (Table 3).

Table 3.

Laparoscopic Pyloromyotomy Complications and Conversions, Presented in Quarters

Quarter	Complications	Conversions
First	Incisional hernia (reoperation)	Nil
Second	Nil	Suspected perforation—no perforation found
Third	Herniation of omentum through port site (reoperation)	Nil
Fourth	Herniation of omentum through port site (reoperation)	Nil

Postoperative course

Time to full feed was 23.8 (14.8–88.5) hours in the open group and 22 (7.6–107.5) hours in the laparoscopic group (P = .090) (Table 4). Postoperative length of stay was 32 (20.4–218.1) hours in the open group and 30.6 (12.3–147.2) hours in the laparoscopic group (P = .470).

Table 4.

Postoperative Results

	Open group (n = 90)	Laparoscopic group (n = 60)	P^a
Time to full feed (hours)	23.8 (14.8–88.5)	22 (7.6–107.5)	.090
Total paracetamol doses (mg/kg)	23.5 (0–169.4)	13.9 (0–95.3)	.0083
No analgesia given (no. of cases)	23	29	.0051
Postoperative length of stay (hours)	32 (20.4–218.1)	30.6 (12.3–147.2)	.47

Paired Student's t-test.

Total paracetamol dose, including intraoperative dosing, was 23.5 (0–169.4) mg/kg for open patients and 13.9 (0–95.3) mg/kg for laparoscopic patients (P = .0083). Results remained significant if patients who received rectus sheath blocks only were analyzed: open (n = 86) 24.25 (0–169.4) mg/kg and laparoscopic (n = 42) 15.4 (0–61.1) mg/kg (P = .0070). Ibuprofen was given to 4 patients in the open group at a total dose of 4.45 (1.1–7.6) mg/kg and to 1 patient in the laparoscopic group at a dose of 4.8 mg/kg. One patient in each group received Oramorph, equating to a total dose of 1.74 mg/kg in the open group and 0.14 mg/kg in the laparoscopic group. The duration of postoperative analgesia was 9 (0–143) hours for open pyloromyotomy and 2 (0–65) hours for laparoscopic pyloromyotomy (P = .0027). In 23 open (25.6%) and 29 laparoscopic (48.3%) patients, no postoperative analgesia was required (P = .005).

Complications

In the open group, complications included 1 incomplete pyloromyotomy and 4 wound infections requiring oral antibiotics (Table 5). Complications in the laparoscopic group included 1 conversion to open for suspected mucosal perforation though no perforation was found, 1 incisional hernia and 2 omental herniations at a port site (P = 1.000). Of these, 1 open and 3 laparoscopic cases required return to theater (P = .302). The overall conversion rate in the laparoscopic group was 1.67%.

Table 5.

Complications

	Open group	Laparoscopic group	P^a
Overall complications (no. of cases)	5	4	1.000
Return to theater (no. of cases)	1	3	0.302

Fisher's exact test.

Discussion

Our results echo those of previous publications, suggesting that laparoscopic pyloromyotomy offers a safe alternative to open pyloromyotomy. However, this work adds strength to the argument for adoption of the laparoscopic technique, as we have demonstrated safety even during the learning curve. Our medium-volume tertiary center is served by 7 consultant pediatric surgeons and 7 registrars. At the start of the study period, all were familiar with the use of laparoscopy in other procedures such as appendicectomy and herniotomy. One consultant introduced laparoscopic pyloromyotomy to the department and supervised the training of the other consultants who mostly did not have experience in the procedure; the registrars were then trained. Despite this, we have encountered reassuringly few complications. The learning curve for laparoscopic pyloromyotomy has previously been estimated to be 35 procedures.¹¹ Previous authors also examined the rate of complications after the learning curve and found a reduction in overall complications when compared with open procedures (18% versus 3.5%, P = .012).¹² As a previous meta-analysis¹⁷ has shown, defining the learning curve for a laparoscopic procedure either by a minimum number of cases or by a set operative time is difficult due to subjective definition of proficiency and varying reports from existing data. Adult learners acquire skills at different rates, and a “one-size-fits-all” approach is not advisable. Instead we adopt a pragmatic approach by ensuring that a consultant or registrar performs the procedure under direct supervision until he or she has the necessary skills to operate independently. This is assessed both in live operating and in simulated training using our laparoscopic box trainer.

The two major complications—incomplete pyloromyotomy and mucosal perforation—are rare. In our study, we experienced neither complication using the laparoscopic technique during the transition period, which is in keeping with reported rates of 0%–2.9% and 0%–3.6%,^6,7,14,19,22 including in centers where laparoscopic pyloromyotomy was well established. Hall et al.¹⁸ estimated that to detect a significant difference in rates of incomplete pyloromyotomy, 1250 patients would be needed to adequately power such a study, and 390,000 needed to examine rates of mucosal perforation. The largest study to date included 2830 patients from nine centers, and found a small, but statistically significant, increase in the rate of incomplete pyloromyotomy with laparoscopy (adjusted difference 0.87%), although the authors concluded that this was unlikely to have a major clinical impact.¹⁸ St. Peter et al.¹⁹ attributed their 0% rate of both complications to using a 2 cm measurement for the length of pyloromyotomy and cautious use of the pyloric spreader. Another study also reported a 0% incomplete laparoscopic pyloromyotomy rate attributed to palpating the pylorus to identify the change in resistance at the pyloroantral and pyloroduodenal junctions.²⁰ We believe existing experience in other laparoscopic and thoracoscopic procedures in our department has given transferable skills.

We found an increased rate of wound infection requiring oral antibiotics in the open group (4.4% versus 0%), which may be due to the umbilical incision falling close to a notoriously “dirty” area of skin. Hall et al.⁶ also reported a higher rate of wound infection with open surgery (4.3% versus 2.3%), despite the routine administration of prophylactic antibiotics. We do not routinely do so and, on the basis of these results, will not change our practice. Of note, there were 2 cases of omental herniation through a port site in our study: both required a return to theater to reduce the omentum. These cases were likely due to removing the instrument during desufflation. As the skin was closed with glue, a tiny corner of omentum would allow the wound to reopen during recovery. As a result, we are now vigilant in removing instruments under direct vision, before desufflation. Ford et al.²³ and Yagmurlu et al.⁷ each reported two similar cases. The only conversion in our study was performed early in the series when the operating surgeon felt a mucosal perforation had taken place. After conversion, no perforation was found.

Total paracetamol requirements were significantly lower in the laparoscopic group, with a majority of patients receiving no intraoperative paracetamol by the end of the study period. This may reflect the anesthetist's changing perception of laparoscopic pyloromyotomy as a “less painful” procedure. Almost half the laparoscopic patients required no oral analgesia at all, which was statistically significant. The results remained significant when only those receiving rectus sheath blocks were compared. Significantly reduced analgesia requirements have been reported in other studies,^19,22,23 including a double-blind randomized control trial (RCT), removing potential observer bias.⁶ The effect of pain on the developing infant's brain includes release of stress hormones leading to remodeling of spinal reflex sensitivity,²⁴ which in the short term affects sleep or feeding, and in the long term leads to aberrant pain behavior or delayed learning.²⁵ In a study of 100 children aged 7–8 years who had open pyloromyotomy in infancy, 25% reported chronic abdominal pain, compared with 5.8% of their sibling controls.²⁶ Similar work in laparoscopic pyloromyotomy has yet to be produced, although a study examining laparoscopic pyloromyotomy suggests that at pressures of 8 mmHg, oxygenation of the brain remains stable and within safe limits.²⁷

We found a significant reduction in operative time with laparoscopic pyloromyotomy compared with open pyloromyotomy, despite the learning curve. In 1997, early on in the adoption of the laparoscopic technique, Ford et al.²¹ found almost inversed results when they compared mean operative times between open (28 minutes) and laparoscopic procedures (41 minutes). In a large-volume center where the technique was well established, mean operative time for both open and laparoscopic cases was 19 minutes by the end of the series.¹⁹

There was a significant increase in both the rate of consultant-performed and consultant-supervised procedures with laparoscopic pyloromyotomies compared with open pyloromyotomies. As this study examines the transition period from the introduction of laparoscopy to becoming the standard technique, this reflects a period of consultants teaching each other, and then teaching registrars under direct supervision. Hall et al.⁶ found higher rates of open procedures performed by trainees (74% versus 37%). However 3 years later, an article from the lead center found the rate of trainee involvement in laparoscopic pyloromyotomy had increased to 73%, with 36% of these cases performed without consultant supervision.²⁸ This suggests that there is a natural progression toward giving trainees more exposure to the technique, as a center gains confidence in performing the procedure.

The difference in time to full feeds or length of stay was not statistically significant between the two groups in our study—this may have been confounded by the change from protocol to ad libitum feeding during the study period. A recent meta-analysis found a decrease of 2.27 hours in time to achieve full feed favoring laparoscopic technique, and a reduction of 2.4 hours in postoperative length of stay,¹⁰ although the clinical impact of these modest findings is questionable. A further study of 1143 patients found that open pyloromyotomy was independently associated with a postoperative length of stay of >1 day when compared with the laparoscopic approach (odds ratio 1.38, 95% confidence interval 1.03–1.84, P = .030).²⁹

Summary

Our results show that the adoption of laparoscopic pyloromyotomy in our institution has not led to increased complication rates, and operative time and analgesia requirements were actually reduced, despite the learning curve.

Footnotes

Disclosure Statement

No competing financial interests exist.

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