Jin-Yao Lai

Preliminary analysis of the forces on the thoracic cage of patients with pectus excavatum after the Nuss procedure

BACKGROUNDnThe Nuss procedure corrects pectus excavatum using a pre-bent bar that generates stress on the chest wall. To investigate the biomechanical effects after the Nuss procedure, we designed a three-dimensional finite element analysis model to analyze the distribution of stress and strain induced in the chest wall.nnnMETHODSnThree patients with pectus excavatum aged 8, 7, and 7 years, were enrolled in this study. The greatest upward displacements of their sternums after the operation were measured from computed tomography images and chest X-ray films. Based on these displacements, we constructed three finite element analysis models for analyzing biomechanical changes in the thoracic cage after the Nuss procedure.nnnFINDINGSnThe simulation results indicated that greatest strain occurred at the third through seventh cartilages, especially where they join the sternum and ribs. A high bilateral stress distribution was also found over the backs of the third to the seventh ribs near the vertebral column.nnnINTERPRETATIONnThe stress and strain induced by the Nuss procedure can be analyzed using our finite element analysis model. Although the stress and strain may have some influence on chest and spine development, a more detailed finite element analysis model is recommended for future study to improve the accuracy of our simulation results.

Costochondral changes in the chest wall after the Nuss procedure: ultrasonographic findings

PURPOSEnThe Nuss procedure is one of the most popular surgeries for correcting pectus excavatum. However, little is known regarding stress and strain on the deformed ribs after inserting the pectus bar. We used ultrasonography to investigate costochondral changes before and after the Nuss procedure.nnnMETHODSnNinety-five patients underwent the Nuss procedure between July 2007 and February 2008 at 2 institutions. Chest ultrasonography, specifically of the bones and cartilage, was performed 1 day before and 1 week after the operation.nnnRESULTSnPostoperatively, all patients showed various degrees of deformation from the second to sixth cartilages bilaterally. The cartilages were not fractured. Of these patients, 28 (29.5%) had significant changes, including acute angulation of the costochondral junction and rib fractures near the pectus bar. These changes were associated with increased age (P < .01) and the degree of postoperative sternum elevation (P < .01). The pectus index and sex were not significant predictors of rib damage.nnnCONCLUSIONSnThe Nuss procedure created significant stress and strain over the deformed cartilages. Approximately 29% of the patients showed localized, self-limited costochondral changes via chest ultrasonography.

Clinical Impacts of Delayed Diagnosis of Hirschsprung’s Disease in Newborn Infants

BACKGROUNDnAsian infants are at a higher risk of having Hirschsprungs disease (HD). Although HD is surgically correctable, serious and even lethal complications such as Hirschsprungs-associated enterocolitis (HAEC) can still occur. The aim of this study was to investigate the risk factors of HAEC, and the clinical impacts of delayed diagnosis of HD in newborn infants.nnnPATIENTS AND METHODSnBy review of medical charts in a medical center in Taiwan, 51 cases of neonates with HD between 2002 and 2009 were collected. Patients were divided into two groups based on the time of initial diagnosis: Group I, diagnosis made within 1 week after birth, and Group II after 1 week. Clinical features including demographic distribution, presenting features of HD, short-term and long-term complications related to HD were compared between the two groups of patients.nnnRESULTSnThere were 25 patients in Group I and 19 in Group II. Group II patients had more severe clinical signs and symptoms of HAEC than Group I patients. The incidence of preoperative HAEC was 12% in Group I and 63% in Group II (adjusted odds ratio = 12.81, confidence interval = 2.60-62.97). Patients with preoperative HAEC were more likely to develop adhesive bowel obstruction after operation (33% vs. 3%, p = 0.013) and failure to thrive (33% vs. 3%, p = 0.013). Also, patients with long-segment or total colonic aganglionosis were at risk of developing both postoperative HAEC (85% vs. 29%, p = 0.001) and failure to thrive (39% vs. 3%, p = 0.002).nnnCONCLUSIONnIn our study, we found that delayed diagnosis of HD beyond 1 week after birth significantly increases the risk of serious complications in neonatal patients. Patients with long-segment or total colonic aganglionosis have higher risk of postoperative HAEC and failure to thrive. Patients with preoperative HAEC are more likely to have adhesive bowel obstruction and failure to thrive.

The measurement and designation of the pectus bar by computed tomography

PURPOSEnThe length of the bar used for the Nuss procedure is typically determined by measuring the distance between the 2 midaxillary lines and subtracting 2.5 cm. However, this may not be accurate for all patients. Measurements of the chest using computed tomography (CT) were developed for better determination of bar length.nnnMETHODSnSeventy-five patients underwent the Nuss procedure between 2005 and 2008. The length and curve of the pectus bar were determined using both the traditional method (TM) and CT.nnnRESULTSnTwelve patients (16%) had length differences (LD) with the methods. The LD and non-LD patients were 18.8 +/- 2.4 and 11.3 +/- 0.6 years old, respectively (P = .005). The proportion of females in the groups was 58.3% (7/12) and 28.6% (18/63), respectively (P = .046). The TM gave a longer bar estimation in all but one patient with a high sternal angulation. Slight bar protrusion was noted in 3 of the 12 patients with LD using TM and 0 of the 9 patients using CT.nnnCONCLUSIONSnComputed tomography measurement is a precise means for determining length, especially in older patients, females with developed breasts, or patients with high sternal angulation. It also allows for better curvature design, preventing multiple intraoperative adjustments.

Prognostic factors and concomitant anomalies in neonatal gastric perforation

OBJECTIVEnNeonatal gastric perforation is a rare and serious issue. This study aimed to highlight the vital clinical features and identify prognostic factors in such cases.nnnDESIGN, SETTING, PATIENTS, INTERVENTIONS, AND MEASUREMENTSnMedical charts from January 1997 through December 2008 were reviewed retrospectively. Neonates with a diagnosis of gastric perforation were included.nnnRESULTSnThirteen patients were identified with a male:female ratio of 9:4. Five (38%) were preterm infants. The mortality rate was 30% (4/13), and the median age of onset was 3 days (range: 1-14 days). The most common presenting sign was abdominal distension, followed by respiratory distress and vomiting. Except for one patient in whom gastric perforation was diagnosed during surgical repair for gastroschisis, all patients had pneumoperitoneum on admission; 70% and 46% of patients had peritonitis and sepsis, respectively. Concomitant gastrointestinal (GI) tract anomalies or disorders included ischemic bowel/necrotizing enterocolitis (5 patients), intestinal malrotation (2), duodenal web (1), hiatal hernia (1), and gastroschisis (1), which necessitated secondary operations during hospitalization in 5 patients. Seven patients had leukopenia on admission, and 9 developed thrombocytopenia in the following 48 h. All patients who died presented with leukopenia on admission and thrombocytopenia in the following 48 h, yielding sensitivity and specificity rates of 100% and 67%, respectively.nnnCONCLUSIONSnNeonatal gastric perforation is often concomitant with GI anomalies or inflammatory/infectious disease. Patients who were outborn and those with leucopenia, peritonitis, and thrombocytopenia development within 48 h were at risk for poor outcome.

Analysis of changes to the anterior chest wall after the Nuss procedure—an objective measurement of pectus excavatum

INTRODUCTIONnWe report a noninvasive method for recording the deviation of the anterior chest wall (ACW) in patients with pectus excavatum before and after the insertion and removal of a Nuss bar.nnnPATIENTS AND METHODnAll patients undergoing the Nuss procedure at our institutions between June 2008 and February 2009 were enrolled in this study. A thermal plastic strip was used to cast the ACW at the skin level along the area corresponding to the tract of the inserted bar. The height of the ACW was defined as the perpendicular length from the xiphoid process to the transverse line drawn between the 2 midaxillary points.nnnRESULTSnBar insertion caused a significant increase in ACW height and width. Bar removal reduced the corrective effects in terms of a significant decrease in ACW height; at the same time, an increase in ACW width was noted.nnnCONCLUSIONnFeature extraction and analyses of permanent contour casts of the ACW help to understand immediate changes in the ACW after the Nuss procedure and may assist in the design of the bar at insertion. The Nuss bar in situ helped to maintain cosmetic benefits to the ACW.

Malignant Renal Tumors in Childhood: Report of 54 Cases Treated at a Single Institution

BACKGROUNDnWilms tumor is the most common primary renal malignancy occurring in childhood. Significant improvement has been made in the treatment of children with Wilms tumor. However, the treatment of patients with non-Wilms renal tumors remains challenging.nnnMETHODSnBetween 1991 and 2010, 70 children with renal tumors were diagnosed at a single institution. Fifty-four patients were histologically confirmed and divided into three groups, including 42 Wilms tumors, seven clear cell sarcomas of kidney, and five malignant rhabdoid tumors. Most patients underwent unilateral nephrectomy and lymph node sampling followed by adjuvant chemotherapy. Twenty-one of these patients subsequently received radiotherapy.nnnRESULTSnDuring follow-up, 12 patients died of progressive disease and one died of operative mortality. One patient with unilateral pleural metastases subsequently underwent hematopoietic stem cell transplantation. The median survival time of all patients was 88 months. Children under 2 years of age at diagnosis with Wilms tumor or clear cell sarcoma of kidney had an excellent survival rate of 100% compared to the 0% survival rate of MRT.nnnCONCLUSIONnYounger age at diagnosis bore a better prognosis than did older age, whereas a diagnosis of malignant rhabdoid tumor portended a worse prognosis. Younger patients and appropriate treatment may have contributed to the improved prognosis of clear cell sarcoma of kidney.

Increase in intrathoracic volume in pectus excavatum patients after the Nuss procedure

In this study, we present finite element analysis models to calculate the increase in intrathoracic volume of pectus excavatum patients after the Nuss procedure. One virtue of our approach is that the measurement of the intrathoracic volume has no time difference and is not affected by postoperative pain, which cannot be achieved with a 2-year difference between pre- and postoperative pulmonary function testing or any other clinical method. The calculations show that the intrathoracic volume of pectus excavatum patients increased by approximately 2.72–8.88% after the Nuss procedure. The increment curve was patient-dependent, although the increment behavior was similar among the six patients examined. The curve of the increase became flat when the elevating force exceeded 80xa0N or the displacement of the lower sternal end exceeded 2.6xa0cm in half of our cases.

A cross-sectional study of lung volume development in pectus excavatum patients: estimating the total lung volume from chest computed tomograph using 3-dimensional volumetric reconstruction

BACKGROUND/PURPOSEnThis study quantified the lung volume development of pectus excavatum (PE) patients using chest computed tomography (CT) 3-dimensional volumetric reconstructions. The technique permits current and retrospective analyses of data from different institutions.nnnPATIENTS AND METHODSnWe analyzed the records of PE patients who underwent chest CT preoperatively between 2005 and 2009 at 3 institutions. All patients were Chinese. A window of -992 to -198 Hounsfield units was chosen for calculating the CT total lung volume (TLV). The data were compared with the data for 73 microtia and other chest-wall tumor patients studied during the same period as a control group.nnnRESULTSnIn total, 377 PE patients with Haller pectus index (PI) of at least 3.2 were identified for this study. Compared with the reported TLV data for 1050 healthy children and our control group, we found little evidence of a decreased TLV in PE patients at any age for either sex. The mean PI did not change significantly between the ages of 3 and 27 years. The PI was inversely correlated with the TLV (P < .001).nnnCONCLUSIONnOur cross-sectional study provides evidence that the TLV of PE patients is within the reference range in children and adolescents.

Surgical Management of Complicated Necrotizing Pneumonia in Children.

BACKGROUNDnThere are no well-established indications for the surgical management of acute necrotizing pneumonitis in children. This study presents our experience regarding this challenging topic.nnnMETHODSnBetween 2002 and 2009, 56 necrotizing pneumonitis patients with empyema were treated surgically. The outcomes were analyzed retrospectively. Computed tomography findings of massive lung necrosis or large cavities involving more than 50% of the involved lobe were deemed to be complicated necrotizing pneumonitis. Patients without the above indications were considered uncomplicated.nnnRESULTSnThirty-one cases were uncomplicated and 25 were complicated. Operative procedures included 38 decortications (31 uncomplicated and seven complicated), 14 wedge resections, and four lobectomies (complicated only). Preoperatively, patients with complicated necrotizing pneumonia had a higher incidence of pneumothorax (32% vs. 14.3%; pxa0=xa00.001), endotracheal intubation (44% vs. 9.7%; pxa0=xa00.008), and hemolytic uremic syndrome (20% vs. 3.2%; pxa0=xa00.01). These patients also had higher incidences of intraoperative transfusion (68% vs. 9.7%; pxa0=xa00.03), major postoperative complications (16% vs. 0%; pxa0=xa00.02), reoperations (16% vs. 0%; pxa0=xa00.02), and longer postoperative stay (19.8xa0±xa024.2xa0days vs. 11.2xa0±xa05.8xa0days; pxa0=xa00.03). Four complicated patients, who initially had decortications and limited resections, underwent reoperations. Compared with uncomplicated patients, those who underwent decortications and wedge resection required longer postoperative stays (23.6xa0±xa09.9xa0days, pxa0<xa00.01 and 21.1xa0±xa030.7xa0days, pxa0=xa00.04, respectively), whereas patients who had lobectomy had a similar duration of recovery (9.0xa0±xa02.1xa0days, pxa0=xa00.23). All patients improved significantly at follow-up.nnnCONCLUSIONnChildren with complicated necrotizing pneumonitis have more preoperative morbidities, more major postoperative complications, and require longer postoperative stays. Aggressive surgical treatment results in significant clinical improvement. Lobectomy in patients with complicated necrotizing pneumonitis may shorten the postoperative course and avoid subsequent surgery.