COPD患者的机械通气

Mechanical Ventilation of COPD / Asthma | Bin Du
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Pplat的监测：吸气暂停时间
Barberis L, Manno E, Guerin C. Effect of end-inspiratory pause duration on plateau pressure in mechanically ventilated patients. Intensive care Med 2003; 29: 130-134
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AECOPD的病理生理
Airway inflammation Steroids Abx Airway narrowing & obstruction IPAP MV Frictional WOB
Shortened muscles, curvature
BDs
AutoPEEP
1.0
12.4
8.4
3.5
0.06
-5
Hubmayr RD, Abel MD, Rehder K. Physiologic approach to mechanical ventilation. Crit Care Med 1990; 18: 103-113
Mechanical Ventilation of COPD / Asthma | Bin Du
Mechanical Ventilation of COPD / Asthma | Bin Du
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动态过度充盈的监测
• 吸气末肺容积(VEI)
– 60”窒息过程中从吸气末至静态FRC的呼气容积 – 需要完全肌松 – 与其他指标相比预测气压伤并无优势
• autoPEEP
确定COPD基础气体交换水平
ABG pH PaCO2 PaO2 SaO2 HCO3 BE LA 7.202 89.2 mmHg 58.9 mmHg 91.9% 37.9 mmol/L 11.9 mmol/L 2.2 mmol/L 考虑思路 • 是否需要处理？ • 平时PaCO2如何？
– 既往结果的提示 – 如果没有既往结果…
Mechanical Ventilation of COPD / Asthma | Bin Du
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动态过度充盈的发病机制
Hubmayr RD, Abel MD, Rehder K. Physiologic approach to mechanical ventilation. Crit Care Med 1990; 18: 103-113
COPD机械通气策略
• 控制性低通气(controlled hypoventilation)
– 最先由Darioli和Perret于1984年提出
• 不同于允许性高碳酸血症(permissive hypercapnia)
– 严重气流梗阻患者难以纠正PaCO2 – 增加分钟通气量可加重过度充盈及死腔
• 纠正高碳酸血症效果有限
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COPD机械通气适应证
• • • • • • 呼吸肌疲劳且濒临呼吸停止 尽管进行充分的保守治疗, PaCO2仍进行性升高 劳累和(或)高碳酸血症导致意识状态恶化 高浓度吸氧治疗无效的低氧血症 痰液清除障碍导致病情恶化 呼吸骤停
Mechanical Ventilation of COPD / Asthma | Bin Du
Mechanical Ventilation of COPD / Asthma | Bin Du
www.csccm.org.cn
Pplat的监测：吸气暂停时间
Barberis L, Manno E, Guerin C. Effect of end-inspiratory pause duration on plateau pressure in mechanically ventilated patients. Intensive care Med 2003; 29: 130-134
Leatherman JW. Mechanical ventilation for severe asthma. Respir Care 2007; 52: 1460-1461
Mechanical Ventilation of COPD / Asthma | Bin Du
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PEEP Elastic WOB
Air trapping IPAP MV? MV? Vt PaCO2 pH PaO2
muscle strength
VE
VCO2
VA
Mechanical Ventilation of COPD / Asthma | Bin Du
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Mechanical Ventilation of COPD / Asthma | Bin Du
VT
Tidal volume
Normal Stiff Lungs
VEE FRC
insp
Trapped gas
exp
Time
Levy BD, Kitch B, Fanta CH. Medical and ventilatory management of status asthmaticus. Intensive Care Med 1998, 24: 105-117.
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COPD患者的机械通气
北京协和医院 杜斌
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利益冲突(Conflicts of Interest)
• • • • • • Tyco Draeger Maquet Hamilton Taema Viasys
Mechanical Ventilation of COPD / Asthma | Bin Du
Mechanical Ventilation of COPD / Asthma | Bin Du
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时间常数(τ)
Tau 呼气容积 残余容积
• 健康成人 • • • 2 x 0.10 = 0.20” 术后气管插管成人 5 x 0.06 = 0.30” COPD成人 15 x 0.06 = 0.90” ARDS成人 8 x 0.03 = 0.24” ARDS患儿 5 x 0.01 = 0.05”
Mechanical Ventilation of COPD / Asthma | Bin Du
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确定COPD基础气体交换水平
ABG pH PaCO2 PaO2 SaO2 HCO3 BE LA 7.202 89.2 mmHg 58.9 mmHg 91.9% 37.9 mmol/L 11.9 mmol/L 2.2 mmol/L 考虑思路 • 如何根据急性发作时 ABG确定平时的PaCO2？ pH ≈ PaCO2 / HCO3 pH ≈ 40/24 ≈ PaCO2 / 37.9
Mechanical Ventilation of COPD / Asthma | Bin Du
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肺泡通气：二室模型
Pi Rc Rc = 4 R1 = 1.0 R2 = 0.5 C1 = 0.20 C2 = 0.40 V 0.3 C1 P1 R1 R2 P2 Rc = 4 R1 = 0.5 R2 = 5.0 C1 = 0.01 C2 = 0.40 . P1(t) – P2(t) = k V k≈ C1R1 – C2R2 C1 + C2 V 0.3 Pi 6.3 P1 5.1 P2 3.6 V1/V2 0.04 k C2 1.0 Pi 3.8 6.8 P1 2.5 2.5 P2 2.5 2.5 V1/V2 0.50 0.50 0 k
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COPD机械通气的目的
• 缓解呼吸肌疲劳 • 改善气体交换，使其恢复至基础水平 • 防止动态过度充盈和（或）auto-PEEP加重，以免导致 循环功能衰竭
Mechanical Ventilation of COPD / Asthma | Bin Du
www.csccm.org.cn
Mechanical Ventilation of COPD / Asthma | Bin Du
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autoPEEP与动态过度充盈
Oddo M, Feihl F, Schaller M, et al. Management of mechanical ventilation in acute severe asthma: practical aspects. Intensive Care Med 2006; 32: 501-510
AECOPD的病理生理
• 机制
– 呼气气流的驱动压降低
• 肺弹性回缩力不明原因的异常下降 • 呼气相吸气肌肉活动导致胸壁向外的回缩力异常升高
– 气道阻力显著升高
• 气道半径缩小 • 呼气相声门裂狭窄
• 后果
– 肺过度充盈（FRC增加到正常值的2倍） – 呼吸系统时间常数增加
Peress L, Sybrecht G, Macklem PT. The mechanism of increase in total lung capacity during acute asthma. Am J Med 1976; 61: 165-169 McCarthy DS, Sigurdson M. Lung elastic recoil and reduced airflow in clinically stable asthma. Thorax 1980; 35: 298-302 Colebatch HJ, Finucane KE, Smith MM. Pulmonary conductance and elastic recoil relationships in asthma and emphysema. J Appl Physiol 1973; 34: 143-153 Cormier Y, Lecours R, Legris C. Mechanisms of hyperinflation in asthma. Eur Respir J 1990; 3:619-624 Collett PW, Brancatisano T, Engel LA. Changes in the glottic aperture during bronchial asthma. Am Rev Respir Dis 1983; 128: 719-723 Pepe PE, Marini JJ. Occult positive end-expiratory pressure in mechanically ventilated patients with airflow obstruction: the auto-PEEP effect. Am Rev Respir Dis 1982; 126: 166-170 Ranieri VM, Grasso S, Fiore T, Giuliani R. Auto-positive end-expiratory pressure and dynamic hyperinflation. Clin Chest Med 1996; 17: 379-394
– 低估实际autoPEEP
• Pplat
– 足够长的吸气暂停时间 – 没有漏气
Oddo M, Feihl F, Schaller M, et al. Management of mechanical ventilation in acute severe asthma: practical aspects. Intensive Care Med 2006; 32: 501-510
ห้องสมุดไป่ตู้
0
0%
100%
1
63.0%
37.0%
3
95.0%
5.0%
•
5 99.9% 0.1%
Mechanical Ventilation of COPD / Asthma | Bin Du
Lung Volume
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动态过度充盈的发病机制
VEI = VT + VEE
Obstructed Lungs