• G H Bouley, R Froman, and H Shah.
• Surgical Intensive Care Unit, Yale New Haven Hospital, CT 06510.
• Heart Lung. 1992 Sep 1; 21 (5): 471-6.

ObjectiveTo compare the degree of dyspnea experienced by ventilator-dependent patients receiving synchronized intermittent mandatory ventilation (SIMV) versus T-piece or pressure support ventilation (PSV) weaning. The relationship between self-reported perceptions of dyspnea and physiologic variables observed during weaning trials was examined. Variables included heart rate, respiratory rate, minute ventilation, and oxygen saturation as measured by a pulse oximeter.DesignQuasi-experimental, counterbalanced design with repeated measures.SettingMedical intensive care unit of a large university-affiliated medical center.PatientsNine mechanically ventilated patients diagnosed with chronic obstructive lung disease. The patients were admitted for respiratory failure between May 1990 to November 1990. Six tolerated SIMV 4 versus T-piece trials; three were placed in the SIMV 8 versus PSV trials.ProcedureEach patient's perception of dyspnea was measured using a visual analog scale (VAS) at the initiation and at 5-minute intervals of 20-minute weaning trials. Physiologic indicators were noted simultaneously with VAS ratings of dyspnea.ResultsFindings indicated no difference in the degree of dyspnea experienced between weaning methods compared. Within-subject regression analysis on VAS scores revealed individual differences in the relationship between physiologic indicators and perceptions of dyspnea.ConclusionsThe patient's experience of dyspnea during the weaning process can be a valuable guide to observe the patient's progress. The VAS serves as a reliable, easy-to-use tool for quantifying the patient's perception of dyspnea.

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