SUMMARY Successful defibrillation depends on delivery of adequate electrical current to the heart; one of the major determinants of current flow is transthoracic resistance (TTR). To study the factors influencing ITR, we prospectively collected data from 44 patients undergoing emergency defibrillation. Shocks of 94-450 J delivered energy were administered from specially calibrated Datascope defibrillators that displayed peak current flow, thereby permitting determination of TTR. Shocks were applied from standard (8.5-cm diameter) or large (13 cm) paddles placed anteriorly and laterally. First-shock TTR ranged from 15-143 Q. There was a weak correlation between TTR and body weight (r = 0.45, p < 0.05) and a stronger correlation between TTR and chest width (r = 0.80, p < 0.01). Twenty-three patients who were defibrillated using standard 8.5-cm paddles had a mean TTR of 67 ± 36 Q2 (+ SD), whereas 21 patients who received shocks using paddle pairs with at least one large (13 cm Methods All defibrillations were performed using Datascope MD2J damped sinusoidal wave form defibrillators. In this defibrillator, when an energy level is selected the energy that will be delivered into a 50-4 resistance is displayed; if any charge leaks off, the display indicates the decline. Thus, at the moment the defibrillator was fired, the exact amount of delivered energy was displayed and recorded. After discharge, the peak current (in amperes) that flowed between the paddles was displayed and recorded.To permit calculation of TTR, each defibrillator was charged to energy settings ranging from 75-460 J, and at each energy level was fired into dummy resistances ranging from 15-150 Q. The resultant peak current flow for each firing was noted and current vs resistance calibration curves were plotted for each energy level ( fig. 1). Thus, knowing the defibrillator used, the energy displayed before firing and the current that resulted permitted us to determine a patient's TTR from each defibrillator's calibration curve.To evaluate the effect of paddle size on TTR, we equipped, at random, some defibrillators with two standard 8.5-cm-diameter paddles and others with one standard 8.5-cm and one specially constructed 13-cmdiameter paddle, and yet others with two 13-cm paddles. Paddles were coated with Hewlett-Packard Redux paste, a low-resistance interface between paddle and skin,3 and placed so that the anterior (positive) paddle was centered over the upper right parasternal area and the lateral (negative) paddle was over the cardiac apex. When paddle pairs of unequal size were used, the smaller paddle was always placed over the 676 Downloaded from http://ahajournals.org by on April 4, 2019

Objective: To determine the risk of ventriculoperitoneal (VP) shunt infections after percutaneous retrograde gastrostomy feeding tube (GT) placement in children with brain tumors. Patients and Methods: All children (age 0–18 years) with primary brain tumors diagnosed and treated at the Hospital for Sick Children, Toronto, Canada, were subjected to a retrospective analysis. Two groups were identified: the study group included children with a VP shunt and a GT; the control group included children with VP shunts only. Each study patient was matched with 2 controls to compare the rate of infections (cohort comparative study). Results: There were 1,167 children diagnosed and treated with primary brain tumors during the study period (1988–2003); 174 (15%) had a VP shunt and 23 (2%) children had both, a VP shunt and a GT. In the study group (n = 17), GTs were inserted at a median time of 80 days (range 6–204 days) after VP shunts. VP shunt infection rate was 23.5% (4/17) compared to 8.8% (3/34) in the control group (OR 3.18; 95% CI 0.622–16.54, p = 0.16). Three (75%) of the infection episodes in the study group presented with an ascending VP shunt infection directly related to the GT insertion or manipulation in the first 6 weeks. These GTs were inserted at 13, 47 and 49 days after VP shunt insertion. Conclusion: Placement of percutaneous retrograde GTs, in the acute phase, in children with brain tumors and VP shunts may increase the risk of ascending meningitis especially if there are early GT-related complications.

INTRODUCTION Oesophagogastric cancers are known to spread rapidly to locoregional lymph nodes and by transcoelomic spread to the peritoneal cavity. Staging laparoscopy combined with peritoneal cytology can detect advanced disease that may not be apparent on other staging investigations. The aim of this study was to determine the current value of staging laparoscopy and peritoneal cytology in light of the ubiquitous use of computed tomography in all oesophagogastric cancers and the addition of positron emission tomography in oesophageal cancer. METHODS All patients undergoing staging laparoscopy for distal oesophageal or gastric cancer between March 2007 and August 2013 were identified from a prospectively maintained database. Demographic details, preoperative staging, staging laparoscopy findings, cytology and histopathology results were analysed. RESULTS A total of 317 patients were identified: 159 (50.1%) had gastric adenocarcinoma, 136 (43.0%) oesophageal adenocarcinoma and 22 (6.9%) oesophageal squamous carcinoma. Staging laparoscopy revealed macroscopic metastases in 36 patients (22.6%) with gastric adenocarcinoma and 16 patients (11.8%) with oesophageal adenocarcinoma. Positive peritoneal cytology in the absence of macroscopic peritoneal metastases was identified in a further five patients with gastric adenocarcinoma and six patients with oesophageal adenocarcinoma. There was no significant difference in survival between patients with macroscopic peritoneal disease and those with positive peritoneal cytology (p=0.219). CONCLUSIONS Staging laparoscopy and peritoneal cytology should be performed routinely in the staging of distal oesophageal and gastric cancers where other investigations indicate resectability. Currently, in our opinion, patients with positive peritoneal cytology should not be treated with curative intent.