Document Detail

Effect of synchronized intermittent mandatory ventilation on respiratory workload in infants after cardiac surgery.
MedLine Citation:
PMID:  11605928     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Synchronized intermittent mandatory ventilation (SIMV) is commonly used in infants and adults. However, few investigations have examined how SIMV reduces respiratory workload in infants. The authors evaluated how infants' changing respiratory patterns when reducing SIMV rate increased respiratory load. The authors also investigated whether SIMV reduces infant respiratory workload in proportion to the rate of mandatory breaths and which rate of SIMV provides respiratory workloads similar to those after tracheal extubation. METHODS: When 11 post-cardiac surgery infants aged 2-11 months were to be weaned with SIMV, the authors randomly applied five levels of mandatory breathing: 0, 5, 10, 15, and 20 breaths/min. All patients underwent ventilation with SIMV mode: pressure control ventilation, 16 cm H2O; inspiratory time, 0.8 s; triggering sensitivity, 0.6 l/min; and positive endexpiratory pressure, 3 cm H2O. After establishing steady-state conditions at each SIMV rate, arterial blood gases were analyzed, and esophageal pressure, airway pressure, and airflow were measured. Inspiratory work of breathing, pressure-time products, and the negative deflection of esophageal pressure were calculated separately for assisted breaths, for spontaneous breaths, and for total breaths per minute. Measurements were repeated after extubation. RESULTS: As the SIMV rate decreased, although minute ventilation and arterial carbon dioxide tension were maintained at constant values, spontaneous breathing rate and tidal volume increased. Work of breathing, pressure-time products, and negative deflection of esophageal pressure increased as the SIMV rate decreased. Work of breathing and pressure-time products after extubation were intermediate between those at a SIMV rate of 5 breaths/min and those at 0 breaths/min. CONCLUSION: When the load to breathing was increased progressively by decreasing the SIMV rate in post-cardiac surgery infants, tidal volume and spontaneous respiratory rate both increased. In addition, work of breathing and pressure-time products were increased depending on the SIMV rate.
H Imanaka; M Nishimura; H Miyano; H Uemura; T Yagihara
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesiology     Volume:  95     ISSN:  0003-3022     ISO Abbreviation:  Anesthesiology     Publication Date:  2001 Oct 
Date Detail:
Created Date:  2001-10-18     Completed Date:  2001-11-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  881-8     Citation Subset:  AIM; IM    
Surgical Intensive Care Unit, National Cardiovascular Center, Suita, Osaka, Japan.
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MeSH Terms
Air Pressure
Cardiac Surgical Procedures*
Heart Defects, Congenital / surgery
Intubation, Intratracheal
Lung Compliance / physiology
Lung Volume Measurements
Postoperative Period
Respiration, Artificial*
Respiratory Function Tests
Respiratory Mechanics / physiology*
Work of Breathing / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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