Comparison of SIMV+PS and AC modes in chronically ventilated children and effects on speechg.

BACKGROUND: Two modes of ventilation commonly used in children requiring chronic home mechanical ventilation (HMV) via tracheostomy are Assist Control (AC) and Synchronized Intermittent Mandatory Ventilation with Pressure Support (SIMV+PS). There has been no study comparing these two modes of ventilation in children requiring chronic HMV. METHODS: We studied children requiring HMV capable of completing speech testing. Study participants were blinded to changes and studied on both modes, evaluating their oxygen saturation, end tidal carbon dioxide (PET CO2 ), heart rate, respiratory rate, and respiratory pattern. Subjects completed speech testing and answered subjective questions about their level of comfort, ease of breathing, and ease of speech. RESULTS: Fifteen children aged 12.3±4.8 years were tested. There was no difference in mean oxygen saturation, minimum oxygen saturation, mean PET CO2 , maximum PET CO2 , mean heart rate, and mean respiratory rate. The maximum heart rate on AC was significantly lower than SIMV+PS, p=0.047. Subjects breathed significantly above the set rate on SIMV+PS (p=0.029), though not on AC. Subjects found it significantly easier to speak on AC, though there was no statistically significant difference in speech testing. Four subjects had multiple prolonged PS breaths on SIMV+PS. Many subjects exhibited an abnormal cadence to speech, with some speaking during both inhalation and exhalation phases of breathing. CONCLUSIONS: There were few differences between AC and SIMV+PS, with a few parameters favoring AC that may not be clinically significant. This includes subjective perception of ease of speech. We also found unnatural patterns of speech in children requiring HMV. This article is protected by copyright. All rights reserved.

Comparison of SIMV + PS and AC modes in chronically ventilated children and effects on speech.

BACKGROUND: Two modes of ventilation commonly used in children requiring chronic home mechanical ventilation (HMV) via tracheostomy are Assist Control (AC) and Synchronized Intermittent Mandatory Ventilation with Pressure Support (SIMV + PS). There has been no study comparing these two modes of ventilation in children requiring chronic HMV. METHODS: We studied children requiring HMV capable of completing speech testing. Study participants were blinded to changes and studied on both modes, evaluating their oxygen saturation, end-tidal carbon dioxide (PETCO2), heart rate, respiratory rate, and respiratory pattern. Subjects completed speech testing and answered subjective questions about their level of comfort, ease of breathing, and ease of speech. RESULTS: Fifteen children aged 12.3 ± 4.8 years were tested. There was no difference in mean oxygen saturation, minimum oxygen saturation, mean PETCO2, maximum PETCO2, mean heart rate, and mean respiratory rate. The maximum heart rate on AC was significantly lower than SIMV + PS, p = .047. Subjects breathed significantly above the set rate on SIMV + PS (p = .029), though not on AC. Subjects found it significantly easier to speak on AC, though there was no statistically significant difference in speech testing. Four subjects had multiple prolonged PS breaths on SIMV + PS. Many subjects exhibited an abnormal cadence to speech, with some speaking during both inhalation and exhalation phases of breathing. CONCLUSIONS: There were few differences between AC and SIMV + PS, with a few parameters favoring AC that may not be clinically significant. This includes the subjective perception of ease of speech. We also found unnatural patterns of speech in children requiring HMV.

Exercise performance in thalassemia major: correlation with cardiac iron burden.

Exercise performance is decreased in patients with Thalassemia major (TM), but the relative impact of anemia and iron overload on exercise capacity is unknown. We assessed the cardiopulmonary function of 71, well-transfused TM patients via graded treadmill exercise stress test. All patients underwent MRI of the heart, pancreas, and liver and diagnostic phlebotomy. Patients ranged in age from 13 to 46 years of age. Fifteen patients were excluded from analysis due to submaximal effort. Mean Vo2 max was 83.0% of predicted and was limited by abnormal cardiovascular mechanisms, consisting of a decreased O2 pulse (86.6% of predicted) in men and decreased maximum heart rate (HR) response (85% of predicted) in women. Patients with hemoglobin less than 12 g/dL had lower O2 pulse and Vo2 max, regardless of sex. Cardiac iron was negatively associated with maximum HR response and Vo2 max (r2 = 0.10 and 0.08, respectively, P < 0.05). Vo2 max was correlated with cardiac R2*, hs-CRP, sex and hemoglobin in decreasing strength of association. In thalassemia, exercise performance is limited by impaired stroke-volume reserve in men and blunted HR response in women. Iron toxicity may be mediated through vascular inflammation and direct modulation of HR response to exercise.

Neurocognitive functioning in children with obstructive sleep apnea syndrome: a pilot study of positive airway pressure therapy.

Studies of individuals with obstructive sleep apnea syndrome (OSAS) have shown impairment in neurocognitive function. This study investigated the neurocognitive function in children with OSAS before and after positive airway pressure (PAP) therapy. Twenty-one participants with suspected/documented OSAS were recruited, completing the Epworth Sleepiness Scale (ESS), the Child Sleep Habit Questionnaire (CSHQ), and/or the Pittsburgh Sleep Quality Index. Participants were administered sections of the Wechsler Intelligence Scale for Children-IV, the Delis Kaplan Executive Functioning Scales, the Test of Everyday Attention for Children, and the Wide Range Assessment of Memory and Learning--2nd Edition to assess neurocognitive function. The ESS and the CSHQ indicate that many participants had excessive daytime sleepiness and increased sleep-disordered breathing. Participants before therapy reflected neurocognitive deficiencies in all areas. Of the original 21 children, 4 completed the full PAP treatment and were reevaluated, demonstrating improvements in memory and motor speed. Children with OSAS reported sleep-disordered breathing, increased daytime sleepiness, and deficiencies in neurocognitive measures. Correcting these sleep impairments appeared to reduce global neurocognitive deficits while improving memory and processing speed.

Pulmonary function in thalassaemia major and its correlation with body iron stores.

This study compared pulmonary function tests (PFTs) with cardiac, pancreatic and liver iron in 76 thalassemia major (TM) patients. Restrictive lung disease was observed in 16%, hyperinflation in 32% and abnormal diffusing capacity in 3%. While no patients met Global Initiative for Chronic Lung Disease criteria for airways obstruction, there were indicators of small airways disease and air trapping. PFTs did not correlate with somatic iron burden, blood counts or haemolysis. Restrictive lung disease was associated with inflammation. We conclude that TM patients have pulmonary abnormalities consistent with small airways obstruction. Restrictive disease and impaired diffusion are less common.