The Flow versus Time Waveform can be used to detect the presence of AutoPEEP. AutoPEEP, frequently called air-trapping, results when the patient is not given enough time to exhale back to baseline. This results in an increased Functional Residual Capacity (FRC), increased mean airway pressure and may make it difficult for the patient to trigger additional breaths from the ventilator.
When patients have an increased airway resistance (possibly due to bronchospasm, secretions, small endotracheal tube, mucosal edema) or an increased compliance (possibly due to emphysema), they are more likely to have AutoPEEP, if the expiratory time is not long enough. Methods of reducing AutoPEEP include reducing airway resistance and lengthening the expiratory time. In most ventilator modes, the expiratory time can be increased by decreasing the inspiratory time or decreasing the respiratory rate.
患者の気道抵抗が増加した時(気管支攣縮、気管支内分泌物、小さい気管内チューブ、粘膜浮腫等のため)、またはコンプライアンスが増加した時(肺気腫等のために)、呼気時間が十分長くない場合はオートPEEPを起こしやすくなります。オートPEEPを減少させる方法としては気道抵抗を減少させる事と呼気時間を長くする事が挙げられます。ほとんどの人工呼吸器のモードでは吸気時間を減少させるか、または呼吸回数を減少させることで呼気時間を長くすることができます。
The following image is an example of a patient being ventilated in Volume-Targeted ventilation. The ventilator settings are: Volume A/C; Respiratory Rate 20/minute; Tidal Volume 0.5 L; Peak Flowrate 60 LPM; Decelerating Flow Waveform; PEEP 0 cm H2O. This patient is not making any spontaneous efforts.
以下の図は容量規定換気によって換気されている患者の例です。人工呼吸器の設定は、容量規定のアシストコントロール、呼吸回数20回/分、一回換気量0.5L、最高流速60LPM、漸減波、PEEP 0 cm H2Oです。この患者は自発呼吸の努力をしていません。
The Flow versus Time Waveform is the second tracing. Notice how the tracing on the graph goes up to the set peak flowrate of 60 LPM, then gradually decreases throughout inspiration because the decelerating ramp flow waveform was selected. When expiration begins, the tracing demonstrates the peak expiratory flow of approximately 50 LPM, and then the tracing gradually returns back up to baseline at the end of expiration. Because the expiratory flow returns to baseline, the patient has no AutoPEEP.
次回へ続きます
日本語訳 マクマーン由香(米国呼吸療法士)
0 件のコメント:
コメントを投稿