Robert M. Spear

High-frequency pressure-control ventilation with high positive end-expiratory pressure in children with acute respiratory distress syndrome

OBJECTIVE Animal models suggest that high-frequency ventilation with low tidal volumes and high positive end-expiratory pressure (PEEP) minimize secondary injury to the lung. We hypothesized that using a high-frequency pressure-control mode of ventilation with high PEEP in children with severe acute respiratory distress syndrome (ARDS) would be associated with improved survival. DESIGN The study was a retrospective and prospective clinical study at a 24-bed tertiary care pediatric critical care unit. Fifty-three patients with severe ARDS were studied during a 37-month period, 30 prospectively and 23 retrospectively. Severe ARDS was defined as (1) rapid onset of severe bilateral infiltrates of noncardiac origin, (2) partial pressure of oxygen (arterial)/fraction of inspired oxygen less than 200 on PEEP of 6 cm H2O or more for 24 hours or longer, and (3) Murray disease severity score greater than 2.5. All patients meeting these criteria underwent ventilation in the pressure-control mode; the protocol for ventilation had the following general guidelines: (1) fraction of inspired oxygen limited to 0.5, (2) mean airway pressure titrated with PEEP to maintain arterial partial pressure of oxygen of 55 mm Hg or greater (7.3 kPa), (3) peak inspiratory pressure minimized to allow hypercapnia (arterial partial pressure of carbon dioxide, 45 to 60 mm Hg (6.0 to 8.0 kPa), and (4) ventilator rates of 40 to 120/min. Percutaneous thoracostomy and mediastinal tubes were placed for treatment of air leak. RESULTS The survival rate was 89% (47/53) in children with severe ARDS. Nonsurvivors had significantly higher peak inspiratory pressures (75 vs 40 cm H2O, p = 0.0006), PEEP (23 vs 17 cm H2O, p = 0.0004), mean airway pressure (40 vs 28 cm H2O, p = 0.04), alveolar-arterial oxygen gradient (579 vs 540 mm Hg, p = 0.03), and oxygenation index (43 vs 19, p = 0.0008) than survivors. Air leak was present in 51% of patients; there was no difference in the incidence of air leak between survivors and nonsurvivors (p = 0.42). CONCLUSIONS The high-frequency positive-pressure mode of ventilation was safe and was associated with an improved survival rate (89%) for children with severe ARDS. Limitation of both inspired oxygen and tidal volume, along with aggressive treatment of air leak, may have contributed to the improved survival rate.

Detection of traumatic brain injury with magnetic resonance imaging and S-100B protein in children, despite normal computed tomography of the brain.

Objective The objective of this study was to obtain data to further define the extent of traumatic brain injury by using S-100B protein and standard noncontrast magnetic resonance imaging with added fluid-attenuated inversion recovery (FLAIR) and gradient echo sequence in children with normal head computed tomography. Design Pilot, single cohort, prospective, clinical diagnostic study. Setting Pediatric intensive care and intermediate care unit in a tertiary care children’s hospital. Patients Children ages 5–18 yrs who sustained traumatic brain injury, had a negative computed tomography of the brain, and were admitted to hospital were eligible for enrollment. Interventions Two blood samples were drawn for S-100B protein analysis: the first (t-1) as soon as possible or close to 6 hrs of injury and the second (t-2) close to 12 hrs from the time of injury. A magnetic resonance image of the brain was obtained within 96 hrs of injury. Measurements and Main Results Seven of 17 patients (41%) had positive magnetic resonance image. Of the seven patients with positive magnetic resonance image, 100% (seven of seven) had a positive magnetic resonance image with FLAIR sequence, 85% (six of seven) with axial T2 sequence and 50% (three of six) with gradient echo sequence. There was no statistically significant difference in S-100B protein concentrations in patients with a positive magnetic resonance image (n = 7) and those with a negative magnetic resonance image (n = 10; p = .40 at t-1 and p = .13 at t-2). The concentration of S-100B protein was statistically significantly higher in patients with head and other bodily injury (n = 9) compared with isolated head injury (n = 6; p = .018 at t-1 and p = .025 at t-2). Patients with a positive magnetic resonance image had a lower Glasgow Coma Scale score and longer duration of hospital stay. Conclusions Magnetic resonance imaging seems to be a useful modality to better define the spectrum of brain injury in children with mild head trauma. The addition of S-100B protein measurement does not seem to be useful in this setting.

Mediastinal tube placement in children with pneumomediastinum: hemodynamic changes and description of technique.

OBJECTIVE To describe the technique, hemodynamic response, and complication rate after the insertion of a percutaneous mediastinal tube for drainage of pneumomediastinum. DESIGN A combined retrospective and prospective study in mechanically ventilated children with pneumomediastinum. SETTING Multidisciplinary pediatric intensive care unit at a childrens hospital. PATIENTS The medical records and chest radiographs of 25 (15 retrospective and 10 prospective) patients who had placement of a mediastinal tube for drainage of pneumomediastinum from 1990 to 1995 were reviewed. Hemodynamic data were collected prospectively in the ten consecutive children from January 1994 to April 1995. INTERVENTION Mediastinal tube placement: The subxyphoid area was cleansed with povidone-iodine and draped. An 18-gauge, thin-walled introducer needle was inserted 1 to 2 cm below the xyphoid process at an angle of 20 degrees from the anterior abdominal wall, directed at the substernal space. Either a 9-Fr or 11-Fr pericardiocentesis catheter was inserted over a wire and advanced to the third intercostal space. The catheter was secured and connected to 10 cm H2O suction, using a standard thoracostomy tube drainage device. MEASUREMENTS AND MAIN RESULTS The size of the mediastinal air column on a lateral chest radiograph was measured before and after placement of the mediastinal tube. The mean change in the size of the mediastinal air column was -1.6 cm (median -1.5, p < .001). In the ten prospective patients, hemodynamic data were recorded immediately before and after placement of a mediastinal tube from previously placed arterial and central venous pressure catheters. The mean hemodynamic changes after the mediastinal tube placement were: heart rate -4 beats/min (median = -1, p = .14); systolic blood pressure 16 mm Hg (median = 10, p = .007); diastolic blood pressure 11 mm Hg (median = 11, p = .005); mean arterial pressure 12 mm Hg (median = 8, p = .005); and central venous pressure -2 mm Hg (median = -1, p = .04). In four patients with pulmonary artery thermodilution catheters, the mean increase in cardiac index immediately following placement of the mediastinal tube was 34%. No complications, including bleeding, cardiac puncture, or infection occurred. CONCLUSIONS These findings suggest that hemodynamic compromise commonly accompanies pneumomediastinum in children. Decompression of the mediastinal space and drainage of the pneumomediastinum, using this simple bedside technique for continuous drainage, can be performed rapidly and safely in children, resulting in immediate hemodynamic improvement, and allowing for continuous drainage.

Near-infrared spectroscopy monitoring to predict postoperative renal insufficiency following repair of congenital heart disease.

Background: Infants undergoing repair or palliation of congenital heart disease are at risk of renal insufficiency. Development of renal insufficiency increases mortality. This project seeks to determine whether intra- and postoperative renal near-infrared spectroscopy (NIRS) monitoring can reliably predict renal insufficiency after cardiac surgery in infants. Methods: In this prospective, observational cohort study 48 patients undergoing repair or palliation of congenital heart disease in the first 6 months of life were studied intraoperatively and on postoperative day 1 and 2. The NIRS mean and nadir were recorded for the 3 time periods, as were urine output, fluid balance, and serum creatinine. Renal insufficiency was defined as rise in creatinine ≥40% from baseline or oliguria for >4 hours. Near-infrared spectroscopy data were compared to creatinine increase, oliguria, and fluid balance on postoperative day 0, 1, and 2 by regression analysis. Results: Mean renal regional saturation on postoperative day 1 has a strong correlation with increase in creatinine (P < .001 and R 2 = .6). Mean renal saturation less than 80% predicts renal insufficiency with a sensitivity of 100% and a specificity of 75% (P < .001). Conclusion: Monitoring of intra- and postoperative renal regional saturation may provide an early, noninvasive marker of renal insufficiency after cardiac surgery in infants. This would be clinically significant if interventions to improve renal regional saturation prevent renal insufficiency.

723 PERIANAL STREPTOCOCCAL CELLULITIS

Group A beta hemolytic streptococci can cause perianal cellulitis. First described by Amrert et al, (AJDC 112:546, 1966), this infection receives little attention in subsequent literature. This study describes 14 patients with perianal streptococcal cellulitis evaluated from 1975 to 1984. Characteristically, the infection caused painful defecation and constipation with an intensely erythematous, well-demarcated perianal rash and blood-streaked stools. The average age of patients was 3.9 years (range 1-10 yrs.); the male:female ratio was 3.7:1. Seven of the 14 children had rectal bleeding, 5 had anal fissures, 6 had constipation. The mean duration of symptoms before diagnosis was 6.2 months (range 1-12 months). Often, previous evaluation included multiple diagnostic tests and local therapies. Mis-diagnoses included simple anal fissure, inflammatory bowel disease, psychogenic stool holding, psoriasis and moniliasis. We established the diagnosis in all patients by culture of affected perianal skin and plating on 5% sheep-blood agar plates. Treatment with oral penicillin resulted in rapid resolution of the rash and disappearance of all complaints. Recrudescence of infection was not uncommon, necessitating a repeat course of oral antibiotics. On followup examination no patient had underlying gastrointestinal or systemic disease.