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Comparison of SIMV + PS and AC modes in chronically ventilated children and effects on speech
Eugene Y Sohn1,2, Katy Peck3, Rory Kamerman-Kretzmer4
1Division of Pediatric Pulmonology and Sleep Medicine, Children's Hospital Los Angeles, USC Keck School of Medicine, Los Angeles, California, USA.
Insights
Assist Control (AC) and Synchronized Intermittent Mandatory Ventilation with Pressure Support (SIMV+PS) showed few differences in children on home mechanical ventilation. AC may offer slight advantages in speech ease and breathing patterns.
Area of Science:
- Pediatric Respiratory Medicine
- Mechanical Ventilation
- Speech Pathology
Background:
- Chronic home mechanical ventilation (HMV) via tracheostomy is common in children.
- Assist Control (AC) and Synchronized Intermittent Mandatory Ventilation with Pressure Support (SIMV+PS) are primary ventilation modes.
- No prior studies have directly compared AC and SIMV+PS in this pediatric population.
Purpose of the Study:
- To compare the efficacy and patient experience of AC versus SIMV+PS in children requiring chronic HMV.
- To evaluate physiological parameters and speech function during ventilation with AC and SIMV+PS.
Main Methods:
- A blinded study involving 15 children (mean age 12.3 years) requiring HMV.
- Participants were assessed on both AC and SIMV+PS modes.
- Evaluated oxygen saturation, end-tidal carbon dioxide (PETCO2), heart rate, respiratory rate, respiratory pattern, speech testing, and subjective comfort.
Main Results:
- No significant differences in oxygen saturation, PETCO2, or heart/respiratory rates were observed between modes.
- Subjects exhibited higher respiratory rates above set levels on SIMV+PS compared to AC.
- AC was subjectively perceived as easier for speech, though objective speech testing showed no significant difference.
Conclusions:
- Few significant physiological differences were found between AC and SIMV+PS in children on HMV.
- AC may offer subtle benefits in subjective ease of speech, though clinical significance is uncertain.
- Abnormal speech patterns, including speaking during inhalation/exhalation, were noted in this HMV population.
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.
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