| A comparison of the effects of assist-control, SIMV, and SIMV with pressure support on ventilation, oxygen consumption, and ventilatory equivalent. | |
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MedLine Citation:
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PMID: 7706102 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: To quantify the ventilatory efficiency of different modes of mechanical ventilation used to achieve full ventilatory support in normal subjects. Modes compared were assist-control, synchronized intermittent mandatory ventilation (SIMV), and SIMV with 10 cm H2O (0.98 kPA) of pressure support. DESIGN: Prospective, randomized blocks repeated measures design. Subjects served as their own controls. SETTING: A university affiliated pulmonary laboratory. SUBJECTS: Ten healthy volunteers, aged 31-54 years. OUTCOME MEASURES: Minute volume, respiratory rate, average tidal volume, oxygen consumption, and ventilatory equivalent. INTERVENTION: Baseline spontaneous ventilation data collection was followed by mechanical ventilation by mouthpiece in each of three modes in a random sequence. All modes used a machine set rate of 12 breaths per minute, VT of 10 cc/kg of ideal body weight, inspiratory time of 1 second, square wave flow pattern and a sensitivity of -1 cm H2O (-0.09806 kPa) to achieve full ventilatory support. Data were collected continuously for 5 minutes and the mean values were reported. Ventilatory equivalent for oxygen is a measure of the efficiency of the ventilatory pump at various work loads and was calculated by dividing VE (BTPS) by the VO2 (STPD). RESULTS: There were significant differences by mode of mechanical ventilation in average tidal volume (p = 0.02), minute volume (p = 0.02), oxygen consumption (p = 0.04), and ventilatory equivalent (p = 0.01) using ANOVA. There was no significant difference (p = 0.66) by mode of ventilation in respiratory rate. Pairwise follow-up comparisons for these variables found that SIMV with pressure support produced a significantly greater average tidal volume, minute volume, oxygen consumption, and ventilatory equivalent than SIMV alone. SIMV with pressure support also produced a significantly greater minute volume and ventilatory equivalent than assist-control. There were no significant differences between assist-control and SIMV. All three modes produced a lower ventilatory equivalent and higher oxygen consumption than spontaneous breathing. CONCLUSIONS: SIMV with pressure support significantly increased minute volume and ventilatory equivalent when compared with assist-control or SIMV alone, and thus was the most efficient mode of full ventilatory support for our subjects. We found no difference in ventilatory efficiency between assist-control and SIMV. All three mechanical modes were less efficient for our subjects than spontaneous breathing. The inspiratory time of 1 second used in this study, although common in clinical practice, may be inadequate for some patients. |
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Authors:
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D C Shelledy; J L Rau; L Thomas-Goodfellow |
Publication Detail:
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Type: Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial |
Journal Detail:
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Title: Heart & lung : the journal of critical care Volume: 24 ISSN: 0147-9563 ISO Abbreviation: Heart Lung Publication Date: 1995 Jan-Feb |
Date Detail:
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Created Date: 1995-05-10 Completed Date: 1995-05-10 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0330057 Medline TA: Heart Lung Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 67-75 Citation Subset: AIM; IM |
Affiliation:
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Department of Respiratory Care, University of Texas Health Science Center at San Antonio 78284-7784, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Analysis of Variance Female Humans Intermittent Positive-Pressure Ventilation / methods* Male Middle Aged Oxygen Consumption / physiology Posture Prospective Studies Respiration* Respiratory Function Tests Tidal Volume |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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