Biomedical subjects

Alan S Graham

Publications and source records attributed to Alan S Graham.

5 recordsLinked to original sources

PubMed2006

Positive end-expiratory pressure and pressure support in peripheral airways obstruction : work of breathing in intubated children.

OBJECTIVES: Children with peripheral airways obstruction suffer the negative effects of intrinsic positive end-expiratory pressure: increased work of breathing and difficulty triggering assisted ventilatory support. We examined whether external positive end-expiratory pressure to offset intrinsic positive end-expiratory pressure decreases work of breathing in children with peripheral airways obstruction. The change in work of breathing with incremental pressure support was also tested. DESIGN AND SETTING: Prospective clinical trial in a pediatric intensive care unit. PATIENTS: Eleven mechanically ventilated, spontaneously breathing children with peripheral airways obstruction. INTERVENTIONS: Work of breathing (using pressure-rate product as a surrogate) was measured in three tiers: (a) Increasing pressure support over zero end-expiratory pressure. (b) Increasing applied positive end-expiratory pressure and fixed pressure support. The level of applied positive end-expiratory pressure at which pressure-rate product was least determined the compensatory positive end-expiratory pressure. (c) Increasing pressure support over compensatory (fixed) positive end-expiratory pressure. MEASUREMENTS AND RESULTS: Increases in pressure support alone decreased pressure-rate product from mean 724+/-311 to 403+/-192 cmH2O/min. Applied positive end-expiratory pressure alone decreased pressure-rate product from mean 608+/-301 to 250+/-169 cmH2O/min. The lowest pressure-rate product (136+/-128 cmH2O/min) was achieved using compensatory positive end-expiratory pressure (12+/-4 cmH2O) with pressure support 16 cmH2O. CONCLUSIONS: For children with peripheral airways obstruction who require assisted ventilation, work of breathing during spontaneous breaths is decreased by the application of either compensatory positive end-expiratory pressure or pressure support.

Airway Obstruction↗

PubMed2006

Ventilator management protocols in pediatrics.

Management of mechanical ventilation is a complex process with outcomes affected by multiple patient and caregiver variable. Well-constructed protocols represent the synthesis of best available evidence regarding ventilator management. In adults, protocols improve important outcomes such as duration of mechanical ventilation, length of stay, and complication rates; however, protocols are not uniformly successful. In pediatrics, the available evidence does not suggest that ventilator management protocols should be adopted routinely, which may be due to pediatric-specific attributes such as a generally shorter weaning duration. Evidence suggests support for protocols to carefully titrate sedation. In addition, daily assessment of SBTs improves patient outcomes and should be more uniformly adopted in pediatrics. Ventilator-related outcomes may be affected by other confounding factors such as nutrition and fluid balance. Specific subpopulations, such as children who have congenital heart disease, may present opportunities for focused use of ventilator management protocols. Protocolized ventilation has an important place in trials of new therapeutic strategies such as surfactant or proning. It is hoped that future research will further define the appropriate use of protocols in the general PICU population. Although specific protocols cannot be routinely recommended, a multidisciplinary team approach to synthesizing available literature and determining best practice is a useful model. This approach will foster "team ownership" of ventilator management by all involved, thus engendering the best possible outcomes for critically ill children who require mechanical ventilation.

Child↗

PubMed2005

Pressure-rate products and phase angles in children on minimal support ventilation and after extubation.

OBJECTIVE: To compare the pressure-rate products and phase angles of children during minimal support ventilation and after extubation. DESIGN AND SETTING: Prospective, randomized single-center trial in a pediatric intensive care unit in a tertiary children's hospital. METHODS: Seventeen endotracheally intubated, mechanically ventilated children were placed on T-piece, T-piece with heliox, continuous positive airway pressure, and pressure support in random order. Esophageal pressure swings, phase angles, respiratory mechanics, and physiological parameters were measured on these modes and after extubation. MEASUREMENTS AND RESULTS: Pressure-rate product postextubation was significantly higher than on support modes. For each mode and after extubation they were: pressure support 198+/-31, continuous positive airway pressure 237+/-30, T-piece 323+/-47, T-piece/heliox 308+/-61, and extubation 378+/-43 cmH2O/min. Phase angles were significantly higher during T-piece ventilation than pressure support but not did not differ significantly from postextubation. CONCLUSIONS: Assessment of effort of breathing during even minimal mechanical ventilation may underestimate postextubation effort in children. Postextubation pressure-rate product and hence "effort of breathing" in children is best approximated by T-piece ventilation.

Child↗

PubMed2005

Maternal infection and risk of cerebral palsy in term and preterm infants.

OBJECTIVE: We tested the hypothesis that term and preterm infants exposed to maternal infection at the time of delivery are at increased risk of developing cerebral palsy (CP). STUDY DESIGN: A population-based case-control study was conducted using Washington State birth certificate data linked to hospital discharge data. Cases (688) were children <or=6 years old, singleton births, hospitalized during 1987 to 1999 with an ICD-9 diagnosis code for CP. Controls were 3,068 singleton birth infants randomly selected from birth records for the same years without CP-related hospitalizations. Infection information was available only for the birth hospitalization. RESULTS: Infants of women who had any infection during their hospitalization for delivery were at increased risk of CP (odds ratio (OR) 3.1, 95% confidence interval (CI) 2.3 to 4.2). This was observed for term deliveries (OR 1.8, 95% CI 1.1 to 2.8) and preterm deliveries (OR 2.3, 95% CI 1.3 to 4.2). CONCLUSIONS: Our results suggest that maternal infection is a risk factor for CP in both term and preterm infants.

Case-Control Studies↗

PubMed2004

Respiratory inductance plethysmography used to diagnose bilateral diaphragmatic paralysis: a case report.

OBJECTIVE: To report the use of respiratory inductance plethysmography in the diagnosis and management for a case of bilateral diaphragmatic paralysis after repeated sternotomies in a 23-month-old child. DESIGN: Case report. SETTING: A 15-bed pediatric cardiothoracic intensive care unit in an academic children's hospital. INTERVENTIONS: The patient could not be weaned from the ventilator after a repeat sternotomy for pulmonary artery reconstruction. Pulmonary function test results were within normal limits, and plain film radiography, ultrasonography, and fluoroscopy were unable to establish a definitive diagnosis. Evaluation of thoracoabdominal synchrony was undertaken using respiratory inductance plethysmography (RespiTrace). The work of breathing was assessed using esophageal manometry to obtain the pressure-rate product. RESULTS: During spontaneous breathing, complete thoracoabdominal asynchrony was noted, with clockwise Konno-Mead loops and associated phase angles of nearly 180 degrees. The pressure-rate product was 120 cm H(2)O/min, indicating elevated work of breathing. The pressure-rate product decreased dramatically, as indicated by measurement and observation, in response to increased levels of continuous positive airway pressure. CONCLUSIONS: The diagnosis of bilateral diaphragmatic paralysis can be confirmed by measurement of thoracoabdominal synchrony. Therapeutic and diagnostic application of continuous positive airway pressure may predict response to diaphragmatic plication. Controlled trials comparing measurement of thoracoabdominal synchrony with standard methods for the early diagnosis of diaphragmatic paralysis are needed.

Diaphragm↗