Document Detail

Immediate response to inspiratory resistive loading in anesthetized patients with kyphoscoliosis: spirometric and neural effects.
MedLine Citation:
PMID:  8919433     Owner:  NLM     Status:  MEDLINE    
In kyphoscoliosis (KS), lung volumes are reduced, respiratory elastance and resistance are increased, and breathing pattern is rapid and shallow, attributes that may contribute to defense of tidal volume (VT) in the face of inspiratory resistive loading. The control of ventilation of 12 anesthetized patients about to undergo corrective spinal surgery was compared to that of 11 anesthetized patients free of cardiothoracic disease during quiet breathing and the first breath through one of three linear resistors. Mean forced vital capacity (FVC) of the KS group was 48% that of the controls (C). Passive elastance (Ers) and active elastance and resistance (E'rs and R'rs, respectively) were computed according to previously described techniques (Behrakis PK, Higgs BD, Baydur A, Zin WA, Milic-Emili J (1983) Active inspiratory impedance in halothane-anesthetized humans. J Appl Physiol 54: 1477-1481). Baseline tidal volume VT, inspiratory duration Tl, expiratory duration TE, duration of total breathing cycle TT, and inspiratory duty cycle TI/TT were significantly reduced, while VE was slightly decreased in the KS. Ers, E'rs, and R'rs, were, respectively, 72, 69, and 89% greater in the KS. Driving pressure (Pmus) was derived from the equation of motion, using active values of respiratory elastance. With resistive loading, there was greater prolongation of TI in the C, while percent reduction in VT and minute ventilation VE was less in KS. Compensation in both groups was achieved through three changes in the Pmus waveform. (1) Peak amplitude increased. (2) The duration of the rising phase increased. (3) The rising Pmus curve became more concave to the time axis. These changes were most marked with application of the highest resistance in both groups. Peak driving pressure and mean rate of rise of Pmus were greater in the KS. Increased intrinsic impedance, Pmus, and differences in changes in neural timing in anesthetized kyphoscoliotics contribute to modestly greater VT defense, compared to that of anesthetized subjects free of cardiorespiratory disease.
A Baydur; M Carlson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Lung     Volume:  174     ISSN:  0341-2040     ISO Abbreviation:  Lung     Publication Date:  1996  
Date Detail:
Created Date:  1997-01-02     Completed Date:  1997-01-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7701875     Medline TA:  Lung     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  99-118     Citation Subset:  IM    
Chest Medicine Service, Rancho Los Amigos Medical Center, Downey, California, USA.
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MeSH Terms
Airway Resistance
Anesthesia, General*
Elastic Tissue
Forced Expiratory Volume
Kyphosis / physiopathology*,  surgery
Lung Volume Measurements
Respiration / physiology*
Respiratory Muscles / innervation*
Scoliosis / physiopathology*,  surgery

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