A porcine model of postoperative hemi-diaphragmatic paresis to evaluate a unilateral diaphragmatic pacemaker.

Unilateral phrenic nerve damage is a dreaded complication in congenital heart surgery. It has deleterious effects in neonates and children with uni-ventricular circulation. Diaphragmatic palsy, caused by phrenic nerve damage, impairs respiratory function, especially in new-borns, because their respiration depends on diaphragmatic contractions. Furthermore, Fontan patients with passive pulmonary perfusion are seriously affected by phrenic nerve injury, because diaphragmatic contraction augments pulmonary blood flow. Diaphragmatic plication is currently employed to ameliorate the negative effects of diaphragmatic palsy on pulmonary perfusion and respiratory mechanics. This procedure attenuates pulmonary compression by the abdominal contents. However, there is no contraction of the plicated diaphragm and consequently no contribution to the pulmonary blood flow. Hence, we developed a porcine model of unilateral diaphragmatic palsy in order to evaluate a diaphragmatic pacemaker. Our illustrated step-by-step description of the model generation enables others to replicate and use our model for future studies. Thereby, it might contribute to investigation and advancement of potential improvements for these patients.

[Influencing factors on operating times for metal bar removal after Nuss repair]. / Einflussfaktoren der Schnitt-Naht-Zeiten der Metallentfernung nach Nuss-Operation.

BACKGROUND: Metal bar removal after the Nuss repair procedure is prone to be cancelled in cases of operating time shortages due it being suitable to be postponed without harming patients. Consequently, planning operation times as exactly as possible could be one solution. OBJECTIVE: Statistical modelling of operation times of metal bar removal after Nuss repair using the prespecified independent predictors of age, sex, intraoperative complications, and number of implanted metal bars. MATERIAL AND METHODS: We included all patients whose operation notes included an operation time, which was modelled via linear regression and subject to internal validation via bootstrap. Exploratory analyses also consisted of the surgeon's experience, the number of stabilizers, the body mass index, and preceding re-do surgery for bar dislocation. RESULTS: We included 265 patients (14% ♀) with a median age of 19 years (interquartile range 17-20 years), of whom 81% had 1 and 17% had 2 metal bars removed. The prespecified regression model was statistically significant (likelihood ratio 56; df = 5; P < 0.001) and had a bias corrected R2 of 0.148. Patient age influenced operation times by 2.1min per year of life (95% confidence interval 1.3-2.9min; P < 0.001) and 16min per explanted metal bar (95% confidence interval: 10-22min; P < 0.001). CONCLUSION: The patient-specific factors of age and the number of explanted metal bars influenced the operation times and can be included into scheduling operation times.

Paediatric Pilonidal Sinus Disease: Early Recurrences Irrespective of the Treatment Approaches in a Retrospective Multi-centric Analysis.

BACKGROUND: Incidences of pilonidal sinus disease are rising. Guidelines rarely consider children and adolescents and evidence for their treatment is rare. The literature is divided on the choice of the preferable surgical procedure. Therefore, we aimed to assess recurrences and complications following different treatment approaches in our multi-centric cohort. METHODS: We retrospectively assessed all patients treated for pilonidal sinus disease in the paediatric surgical departments of Bonn and Mainz between 01/01/2009 and 31/12/2020. Recurrences were defined according to the German national guidelines. The pre-specified analysis via logistic regression included the operative approach, age, sex, use of methylene blue, and obesity as independent predictors. RESULTS: We included 213 patients, of which 13.6% experienced complications and 16% a recurrence. Median time to recurrence was 5.8 months (95% confidence interval: 4.2-10.3), which was slightly higher in children than adolescents (10.3 months, 95% confidence interval: 5.3-16.2 vs. 5.5 months, 95% confidence interval: 3.7-9.7). None of the investigated procedures, excision and primary closure, excision and open wound treatment, pit picking, and flap procedures had a decisive advantage in terms of complications or recurrence. Of the independent predictors, only obesity was associated to complications (adjusted odds ratio: 2.86, 95% confidence interval: 1.05-7.79, P = 0.04). CONCLUSIONS: We did not find a difference between the investigated procedures, but our analysis is limited by the small sample size in some subgroups. Our data corroborates that recurrences in paediatric pilonidal sinus disease occur early. Factors linked to these differences remain unknown.

Epigastric hernias in children and the use of ultrasound in its diagnosis.

Introduction: There is a paucity of clinical data on pediatric epigastric hernias despite them accounting for up to 6% of all hernia repairs in children. We aimed to provide additional data to supplement those 117 cases of a recent systematic review and to further clarify the role of ultrasound in diagnosing pediatric epigastric hernia. Methods: We retrospectively included all 60 patients treated for epigastric hernias in children in two tertiary pediatric surgical departments within 12 years. Associations were tested via point-biserial correlation analyses. Results: Epigastric hernias primarily affected preschool children with a median age of 39 months. The vast majority of patients (88%) presented with swelling that was occasionally (30%) accompanied by pain. Fascial defects could be found during clinical examination in 45% of patients with a median size of 5 mm (95% CI 3 to 10). Smaller defects were less likely to be palpable (r=-0.44, 95% CI -0.08 to -0.7, p=0.021). Likewise, ultrasound was used more frequently with smaller fascial defect sizes (r=-0.51, 95% CI -0.16 to -0.74, p=0.007). Laparoscopic repair was used in 11 patients (19%) and more often (4/11) in combination with another simultaneous procedure than open repair (11/48). Conclusions: Epigastric hernias are primarily a condition of the preschool child. Ultrasound can be beneficial if the diagnosis cannot be made clinically; otherwise, it is abdicable if it does not change the management of the patient's epigastric hernia. Laparoscopic repairs might be beneficial for children with multiple defects or simultaneous procedures.

Changes in Pulmonary Functions of Adolescents with Pectus Excavatum Throughout the Nuss Procedure.

BACKGROUND: We aimed to determine the longitudinal changes in pulmonary functions of adolescents with Pectus Excavatum who underwent the Nuss procedure, the minimally invasive repair of pectus excavatum (MIRPE). METHODS: Lung function measurements were performed before bar implantation (T0), at least six weeks to ten months after implantation (T1a), at least eleven months to sixty-one months after bar implantation (T1b) and at least two weeks after bar explantation (T2). RESULTS: Data of 114 patients (83.3% male) whose median age at implantation was 15.6 years and at explantation 18.7 years were analyzed. Shortly after implantation at T1a a significant decline of vital capacity (VC; n = 82), forced vital capacity (FVC; n = 78) and forced expiratory volume in 1 second (FEV1; n = 80) compared to T0 was seen. At T1b a significant decline for the residual volume (RV; n = 83), the residual volume/total lung capacity ratio (RV/TLC; n = 81), the total specific airway resistance (sRaw; n = 80) and the total airway resistance (Raw; n = 84) also compared to T0 was measured. In the comparison of T1b to T2 a significant increase of VC, FVC (n = 67), FEV1 (n = 69), TLC (n = 67) and a significant decrease of Raw (n = 66), sRaw, RV (n = 65) and the RV/TLC (n = 64) ratio could be observed. In the direct analysis between T0 and T2, after the explantation of the bar a significant increase in VC (n = 54), FVC (n = 52), and TLC (n = 55) and a significant decrease of RV (n = 51) and the RV/TLC index (n = 50), and in airway resistance parameters like Raw (n = 52) and sRaw (n = 51) could be detected. CONCLUSIONS: Lung function values along with markers of airway resistance improve in patients after the complete procedure of MIRPE. LEVEL OF EVIDENCE: Level II.

Complications following metal bar removal after Nuss repair are rare in a duocentric retrospective evaluation.

PURPOSE: Minimally invasive pectus excavatum repair has gained widespread acceptance and its results and complications are well-described. However, there is a substantial debate on the risks and frequencies of complications following metal bar removal. We, therefore, aimed to analyse all complications that occurred during and after metal bar removal at our two paediatric surgical centres. METHODS: Bar removal surgeries were identified via procedural codes and electronic records were reviewed using a pre-specified data extraction chart. Both intra- and postoperative complications were included and the latter scored according to Clavien-Dindo. We analysed the influence of the pre-specified potential predictors age, sex, and the number of implanted metal bars on the occurrence of complications using logistic regression. RESULTS: We included 279 patients with a median age of 19 years (interquartile range 17-20 years). 15 patients experienced 17 complications. Of 11 postoperative complications, only an enlarging pleural effusion required a chest drain in local anaesthesia, resulting in a Claven-Dindo grade IIIa, whereas the remainder were classified as grade I. Neither age (adjusted odds ratio (aOR) 0.97, 95% confidence interval (CI) 0.84-1.13, P = 0.73), nor sex (aOR 0.88, 95% CI 0.19-4.07, P = 0.87) or the number of bars (aOR 0.64, 95% CI 0.15-2.71, P = 0.547) did influence the occurrence of complications. CONCLUSION: Complications following metal bar removal were scarce in our duocentric retrospective series and usually of minor relevance. However, to address the perceived paucity of data on the frequency and severity of complications following metal bar removal, further studies, including large database research is necessary.

Paediatric surgical trials, their fragility index, and why to avoid using it to evaluate results.

BACKGROUND: The fragility index has been gaining ground in the evaluation of comparative clinical studies. Many scientists evaluated trials in their fields and deemed them to be fragile, although there is no consensus on the definition of fragility. We aimed to calculate the fragility index and its permutations for paediatric surgical trials. METHODS: We searched pubmed for prospectively conducted paediatric surgical trials with intervention and control group without limitations and calculated their (reverse) fragility indices and respective quotients along with posthoc-power. Relationships between variables were evaluated using Spearman's ρ. We also calculated S values by negative log transformation base-2 of P values. RESULTS: Of 516 retrieved records, we included 87. The median fragility index was 1.5 (interquartile range: 0-4) and the median reverse fragility index was 3 (interquartile range: 2-4), although they were statistically not different (Mood's test: χ2 = 0.557, df = 1, P = 0.4556). P values and fragility indices were strongly inversely correlated (ρ = - 0.71, 95% confidence interval: - 0.53 to - 0.85, P < 0.0001), while reverse fragility indices were moderately correlated to P values (ρ = 0.5, 95% confidence interval: 0.37-0.62, P < 0.0001). A fragility index of 1 resulted from P values between 0.039 and 0.003, which resulted in S values between 4 and 8. CONCLUSIONS: Fragility indices, reverse fragility indices, and their respective fragility quotients of paediatric surgical trials are low. The fragility index can be viewed as no more than a transformed P value with even more substantial limitations. Its inherent penalisation of small studies irrespective of their clinical relevance is particularly harmful for paediatric surgery. Consequently, the fragility index should be avoided.

Inguinal hernia repair in inpatient children: a nationwide analysis of German administrative data.

BACKGROUND: Contrary to adult inguinal hernia surgery, large-scale investigations using registries or administrative data are missing in paediatric surgery. We aimed to fill this gap by analysing German administrative hospital data to describe the current reality of inpatient hernia surgery in children. METHODS: We analysed aggregated data files bought from the German federals statistics office on hospital reimbursement data separately for principal diagnoses of inguinal hernia in children and for herniotomies in inpatients. Developments over time were assessed via regression and differences between groups with nonparametric comparisons. RESULTS: Principal diagnoses of hernias were decreasing over time with the exception of male bilateral and female bilateral incarcerated hernias in the first year of life which increased. The vast majority of operations were conducted via the open approach and laparoscopy was increasingly only used for females older than 1 year of age. Recurrent hernia repair was scarce. Rates of inguinal hernia repair were higher in both sexes the younger the patient was, but were also decreasing in all age groups despite a population growth since 2012. The amount of inguinal hernia repairs by paediatric surgeons compared to adult surgeons increased by 1.5% per year. CONCLUSIONS: Our results corroborate previous findings of age and sex distribution. It demonstrates that inpatient hernia repair is primarily open surgery with herniorrhaphy and that recurrences seem to be rare. We observed decreasing rates of hernia repairs over time and as this has been described before in England, future studies should try to elucidate this development. LEVEL OF EVIDENCE: III.

Pilonidal sinus disease on the rise: a one-third incidence increase in inpatients in 13 years with substantial regional variation in Germany.

PURPOSE: Collective evidence from single-centre studies suggests an increasing incidence of pilonidal sinus disease in the last decades, but population-based data is scarce. METHODS: We analysed administrative case-based principal diagnoses of pilonidal sinus disease and its surgical therapy between 2005 and 2017 in inpatients. Changes were addressed via linear regression. RESULTS: The mean rate of inpatient episodes of pilonidal sinus disease per 100,000 men increased from 43 in 2005 to 56 in 2017. In females, the mean rate of inpatient episodes per 100,000 women rose from 14 in 2005 to 18 in 2017. In the whole population, for every case per 100,000 females, there were 3.1 cases per 100,000 males, but the numbers were highly variable between the age groups. There was considerable regional variation within Germany. Rates of inpatient episodes of pilonidal sinus disease were increasing in almost all age groups and both sexes by almost a third. Surgery was dominated by excision of pilonidal sinus without reconstructive procedures, such as flaps, whose share was around 13% of all procedures, despite recommendations of the national guidelines to prefer flap procedures. CONCLUSION: Rates of inpatient episodes of pilonidal sinus disease in Germany rose across almost all age groups and both sexes with relevant regional variation. The underlying causative factors are unknown. Thus, patient-centred research is necessary to explore them. This should also take cases into account that are solely treated office-based in order to obtain a full-spectrum view of pilonidal sinus disease incidence rates.

Circumcision and its alternatives in Germany: an analysis of nationwide hospital routine data.

BACKGROUND/PURPOSE: Circumcisions are among the most frequent operations in children. Health service data on circumcision in the United States has documented an increase in neonatal circumcisions since 2012. We investigated whether a similar effect could be found in Germany, which does not endorse neonatal circumcision. METHODS: We analysed German routine administrative data for operations conducted on the preputium in order to analyse the frequency, age distribution, and time-trends in hospital-based procedures on a nationwide basis. RESULTS: There were 9418 [95% confidence interval (CI) 8860-10,029] procedures per year, of which 4977 (95% CI 4676-5337) were circumcisions. Age distributions were highly different between both circumcisions (van der Waerden's χ² = 58.744, df = 4, P < 0.0001) and preputium-preserving operations (van der Waerden's χ² = 58.481, df = 4, P < 0.0001). Circumcisions were more frequent in the first 5 years of life and above 15 years of age, whereas preputium-preserving procedures were preferred in the age groups between 5 and 14 years of age. The number of circumcisions and preputium-preserving operations decreased in absolute and relative numbers. CONCLUSIONS: The increasing trend towards neonatal circumcision observed in the United States is absent in Germany. The majority of patients were operated after the first year of life and absolute and relative numbers of hospital-based procedures were decreasing. Other factors such as increasing use of steroids for the preferred non-operative treatment of phimosis may play a role. As operations in outpatients and office-based procedures were not covered, additional research is necessary to obtain a detailed picture of circumcision and its surgical alternatives in Germany. LEVEL OF EVIDENCE: III.

The incidence of infantile hypertrophic pyloric stenosis nearly halved from 2005 to 2017: analysis of German administrative data.

PURPOSE: Some paediatric surgical diseases showed a declining incidence in recent years, among which hypertrophic pyloric stenosis has been particularly striking shortly in the years after the millennium. We aimed to assess whether this development continued over the following decade, as it might offer the chance to better understand the underlying reasons. METHODS: We analysed data files obtained from the German federal statistics office for principal diagnosis of hypertrophic pyloric stenosis and pyloromyotomies from 2005 to 2017. Changes over time were assessed via linear regression for incidences per 1000 live births. RESULTS: In the respective time interval, there were a mean of 1009 pyloromyotomies (95% CI 906-1112) per year, of which a mean of 835 (95% CI 752-917) were performed in boys. The incidence of hypertrophic pyloric stenosis per 1000 live births almost halved between 2005 and 2017: it decreased by 0.12 pylorotomies annually (95% CI 0.09-0.14; P < 0.0001) in boys-from a maximum of 2.96 to a minimum of 1.63-and 0.03 pyloromyotomies annually (95% CI 0.02-0.04; P < 0.0001) in girls-from a maximum of 0.64 to a minimum of 0.28. There was considerable regional variation in incidences between the German länder. CONCLUSION: The decreasing incidence of hypertrophic pyloric stenosis noted around the millenium continued into the following decades. The underlying reasons are unclear, which should prompt further research on the subject matter.

Meta-analyses in paediatric surgery are often fragile: implications and consequences.

PURPOSE: Meta-analyses occupy the highest level of evidence and thereby guide clinical decision-making. Recently, randomised-controlled trials were evaluated for the robustness of their findings by calculating the fragility index. The fragility index is the number of events that needs to be added to one treatment arm until the statistical significance collapses. We, therefore, aimed to evaluate the robustness of paediatric surgical meta-analyses. METHODS: We searched MEDLINE for paediatric surgical meta-analyses in the last decade. All meta-analyses on a paediatric surgical condition were eligible for analysis if they based their conclusion on a statistically significant meta-analysis. RESULTS: We screened 303 records and conducted a full-text evaluation of 60 manuscripts. Of them, 39 were included in our analysis that conducted 79 individual meta-analyses with significant results. Median fragility index was 5 (Q25-Q75% 2-11). Median fragility in relation to included patients was 0.77% (Q25-Q75% 0.29-1.87%). CONCLUSION: Paediatric surgical meta-analyses are often fragile. In almost 60% of results, the statistical significance depends on less than 1% of the included population. However, as the fragility index is just a transformation of the P value, it basically conveys the same information in a different format. It therefore should be avoided.

A Continuous Suture Anastomosis Outperforms a Simple Interrupted Suture Anastomosis in Esophageal Elongation.

INTRODUCTION: Long-gap esophageal atresia represents a distinct entity among the esophageal atresia spectrum. In many patients, achieving a reasonable anastomosis depends on some millimeters of tissue. We aimed to determine what effect the suturing technique would have on esophageal ex vivo elongation as it may determine the strength of a primary anastomosis. MATERIALS AND METHODS: In an analysis of porcine esophagi from animals for slaughter (100-120 days old with a weight of 100-120 kg), we determined esophageal length gain of simple continuous and simple interrupted suture anastomoses subjected to linear traction until linear breaking strength was reached. Statistical power of 80% was ensured based on an a priori power analysis using five specimens per group in a separate exploratory experiment. RESULTS: The simple continuous suture anastomosis in 15 porcine esophagi ( = 4.47 cm, 95% confidence interval: 4.08-4.74 cm) outperformed the simple interrupted suture anastomosis in another 15 esophagi ( = 3.03 cm, 95% confidence interval: 2.59-3.43 cm) in length gain (Δ = 1.44 cm, 95% confidence interval: 0.87-2.01 cm, p < 0.0001). CONCLUSION: Simple continuous anastomoses achieved higher length gain compared with simple interrupted suture anastomoses. This effect warrants an experimental assessment in vivo to assess its potential merits for clinical applicability.

Laparoscopy for Abdominal Testes: Nationwide Analysis of German Routine Data.

Introduction: Laparoscopy has been used for the evaluation of impalpable testes for more than 30 years. However, its use for intra-abdominal testes has never been evaluated in a population-based approach. Neither has the share of timely orchiopexies of intra-abdominal testes according to published guidelines. We aimed to provide this information by using nationwide administrative data for hospital reimbursements. Materials and Methods: We obtained data for procedures for exploration and orchiopexy of intra-abdominal testes in Germany from 2005 through 2018 and analyzed them with linear regression for the use of laparoscopy and timely repair. Results: In 2005, laparoscopy was already used in more than 60% of explorations, which composed 76% (95% confidence interval [CI]: 72 to 79) of children operated before their first birthday and 68% (95% CI: 65 to 70) of children up to 4 years of age. Throughout the study period, laparoscopy became increasingly popular for orchiopexy of intra-abdominal testes with a yearly increase of 1.8% (95% CI: 1.2 to 2.5, P < .001) in the first year of life and 1.3% (95% CI: 0.2 to 3.4, P < .001) until the age of 4. The share of patients treated before their first birthday increased yearly by 1.9% for explorations and 1.6% for orchiopexies (P < .001 for both) but did not exceed 30% in 2018. Conclusion: Laparoscopy is the method of choice for exploration of intra-abdominal testes and orchiopexy. In this study, more than 70% of boys were treated after their first birthday, thus not meeting the time limit set by guidelines.

Point-of-care multiplex-PCR enables germ identification in haemolytic uremic syndrome 94 h earlier than stool culture.

Haemolytic uremic syndrome often affects children causing a relevant morbidity and mortality. We compared the time to diagnosis by multiplex-PCR and stool culture in 15 children from two centres. Multiplex-PCR accelerated the time to diagnosis by 94 (95% confidence interval, 80-119; P = 0.0007) hours. Multiplex-PCR offers a time advantage of stool culture that may aid in earlier identification of outbreak clusters.

Comparing Aachen Minipigs and Pietrain Piglets as Models of Experimental Pediatric Urology to Human Reference Data.

INTRODUCTION: Swine had special roles in the development of minimally invasive procedures to treat vesicoureteral reflux, and minipigs have been gaining ground in recent years in experimental pediatric urology as they combine small size with less vulnerable adult physiology, but their suitability as a model has never been assessed. We therefore compared a landrace piglet with a juvenile minipig to elucidate comparability. METHODS: We evaluated five 3-week old Pietrain piglets and five 3-month old Aachen Minipigs as representatives of landrace and minipig models based on their expected bodyweight being similar to a newborn human. We compared renal weight, volume - via the ellipsoid formula - and ureteral length. In addition, we calculated porcine renal function via Gasthuys' formula. In order to compare the groups with previously published values for infants, we used resampling techniques to allow comparison to humans. RESULTS: Renal weight was higher in humans than in Pietrain piglets (ΔL = 7.6 g; ΔR = 5.4 g) and Aachen Minipigs (ΔL = 11 g; ΔR = 9.4 g). Renal volumes in humans were higher than in both Pietrain piglets (ΔL = 5.6 mL, p < 0.001; ΔR = 3.7 mL, p = 0.004) and Aachen Minipigs (ΔL = 8.1 mL; ΔR = 6.6 mL; both p < 0.001). Ureteral lengths in humans and both pig breeds were comparable as were estimated renal functions between both pig breeds. DISCUSSION AND CONCLUSION: Both landrace piglets and juvenile minipigs are suitable models for experimental pediatric urology as parameters did not differ between them. In addition, the anatomic parameters are comparable or smaller than in infants. This might facilitate translational research as technical failure is less likely in larger organs. Additional research is necessary to cover higher age ranges than those included in the present pilot study.

Pediatric Surgical Research Output in Germany in the Last 30 Years - An Assessment and International Comparison of Three Dedicated Paediatric Surgical Journals.

Purpose: Research output of once-leading countries in surgical journals is decreasing despite an overall increase of scientific publications by 8% per year. We aimed to assess research outputs of German, Dutch, and Israeli pediatric surgeons in dedicated pediatric surgical journals in order to get insight into trends in pediatric surgical research. Methods: We collected bibliographic information on all original articles in the Journal of Pediatric Surgery, European Journal of Pediatric Surgery, and Pediatric Surgery International in 1985-1988, 2000-2003, and 2015-2018 that had a German, Dutch or Israeli last author from a department of pediatric surgery. Citation counts were obtained from the Web of Science. Results: Research output of German pediatric surgery decreased from 19 manuscripts in 1988 (0.1/surgeon/year) to eight manuscripts in 2017 (0.02/surgeon/year), whereas those of the Netherlands increased from two manuscripts in 1985 (0.08/surgeon/year) to 12 manuscripts in 2016 (0.3/surgeon/year). The declining German research output negatively correlated with increasing numbers of specialist pediatric surgeons for total (τ = -0.54; P = 0.0156) and manuscripts per surgeon (τ = -0.79; P = 0.0001), resulting in a negative trend over time (χ2 = 11.845, P = 0.0006). Analyses of citation patterns revealed that manuscripts by Dutch pediatric surgeons and those published in the Journal of Pediatric Surgery had higher absolute citation counts than the reference category of a German manuscript in the European Journal of Pediatric Surgery. Age-corrected citation rates resembled this result by increasing from 2000 to 2003 ( x ˜ = 0.799, range: 0-3.368) to 2015-2018 ( x ˜ = 2, range: 0-5) (P = 0.035) for the Netherlands. Assessment of manuscript types revealed that the proportion of prospective studies increased in the German sample (χ2 = 5.05, P = 0.0246), but remained the lowest among the comparators. Surprisingly, the proportion of non-clinical manuscripts from Germany also increased over time (χ2 = 4.001, P = 0.0455), whereas it remained constant in both the Netherlands and Israel. Conclusion: German pediatric surgical research output decreased in the last thirty years based on the sample of dedicated pediatric surgical journals, while Dutch productivity increased. Citation rates-as a measure of scientific impact-were associated and increased with Dutch manuscripts. The involved factors remain to be determined and whether this represents a shift toward other journals or mirrors a general development.

Using multidimensional scaling in model choice for congenital oesophageal atresia: similarity analysis of human autopsy organ weights with those from a comparative assessment of Aachen Minipig and Pietrain piglets.

Swine models had been popular in paediatric oesophageal surgery in the past. Although being largely replaced by rodent models, swine experienced a revival with the establishment of minipig models. However, none of them has ever been investigated for similarity to humans. We conducted a pilot study to determine whether three-week old Pietrain piglets and three-month old Aachen Minipigs are suitable for experimental paediatric oesophageal atresia surgery. We tested the operation's feasibility, performed a necropsy, weighed organs, measured organ length and calculated relative weights and lengths, and measured laboratory parameters. We used multidimensional scaling to assess the similarity of the swine breeds with previously published human data. Pietrain piglets had a higher a priori bodyweight than Aachen Minipigs (Δ = 1.31 kg, 95% confidence interval (CI): 0.37-2.23, p = 0.015), while snout-to-tail length was similar. Pietrain piglets had higher absolute and relative oesophageal lengths (Δ = 5.43 cm, 95% CI: 2.2-8.6; p = 0.0062, q1* = 0.0083 and Δ = 11.4%, 95% CI: 5.1-17.6; p = 0.0025, q3* = 0.0053). Likewise, absolute and relative small intestinal lengths were higher in Pietrains, but all other parameters did not differ, with the exception of minor differences in laboratory parameters. Multidimensional scaling revealed three-week old Pietrain piglets to be similar to two-month old humans based on their thoracoabdominal organ weights. This result indicates three-week old Pietrain piglets are a suitable model of paediatric oesophageal atresia surgery, because clinically many procedures are performed at around eight weeks age. Three-month old Aachen Minipigs were more dissimilar to eight-week old humans than three-week old Pietrain piglets.