呼吸力學的知識ppt課件

1、機械通氣的呼吸力學Respiratory mechanics of mechanical ventilationWWW,Xiangyu Zhang, MD, FCCP 張翔宇 SICU Shanghai Tenth Peoples Hospital Shanghai Tongji University Shanghai, China,呼吸機波形與參數(shù),壓力pressure 近端壓力 遠端壓力 氣管內壓力 食管壓力，內源性PEEP 容量volume，壓力-容量環(huán) 流量flow，流速-容量環(huán) 呼吸做功，等,基本圖形,Flow,Volume,Pressure,P-V loop,F-V loop,各壓

2、力參數(shù),吸氣峰壓（PIP） PIP = PRAW + Pplateau 平臺壓（ Pplateau） Pplateau = VT/CRS 呼氣末壓（EEP） 氣道阻壓（PRAW） PRAW = RAW （flow rate,呼吸力學監(jiān)測,順應性（Compliance） 靜態(tài)順應性（Cst ） Cst = VT/（Pplateau PEEP） 動態(tài)順應性(Cdyn) Cdyn = VT/（PIP PEEP） 氣道阻力(RAW) RAW = PRAW/(flow rate) : 23 (cmH2OL/s) 包括呼吸道與氣管導管的阻力,Airway Pressure (VCV,Airway Pres

3、sure (VCV,壓 力,Why Spontaneous Breath Should Be Needed,Better cardiac output Better ventilation/perfusion Better end expiratory lung volume (EELV) Better clinical outcome,Current Opinion in Critical Care 2005, 11:6368,Christian Putensen,August, 2006,Current Opinion in Critical Care 2002, 8:5157,Fabry

4、 Chest 1995:107:1387,Asynchrony is still a problem,Patient-ventilator asynchrony during assisted mechanical ventilation ArnaudW. Thille Pablo Rodriguez Belen Cabello Franois Lellouche Laurent Brochard Intensive Care Med (2006) 32:15151522,Ti in PSV,Inspiration termination Criteria (Esens,25% of peak

5、 flow in most cases,壓力上升時間與吸氣終止,Overshoot,supraplateau,Intrathoracic pressures,TRACHEAL PRESSURE,PROX. AIRWAY PRESSURE,PLEURAL PRESSURE,ALVEOLAR PRESSURE,Resp Lab MGH,Asia Vent Forum Shanghai TCI,亞洲通氣論壇,Our study settings,Pressure Support,P circuit P eso P plural,Rise time 1,P circuit P eso P plural

6、,Rise time 1,P circuit P eso P plural,Rise time 100,P circuit P eso P plural,Esens 1,P circuit P eso P plural,Esophageal Balloon,Approximates pleural pressure Polyethylene 10 cm long balloon 100 cm long tubing Positioned in the lower 1/3 of the esophagus Filled with 0.5-1.0cc air,Proper placement of

7、 the balloon is imperative for accurate measurements. An approximate level of placement can be made by measuring the distance from the tip of the nose to the bottom of the earlobe and then from the earlobe to the distal tip of the xiphoid process,Baydur Method, to confirm balloon placement,Calculati

8、ons based on differential pressures,Tracheal Pressure Measurements,Intended typically for intermittent use More accurately displays actual pressures transmitted to the airways Provides ability to measure imposed Work and Resistance,Tracheal Pressures,Measures pressure at distal end of endotracheal t

9、ube 5 Fr polyethylene tube PAW-PTR/Flow (L/s) = Resistance of ETT Advance Tracheal Pressure catheter to 1 cm less than ET plus adapters Withdraw 1-2cm if patient continues to cough,Evaluation of pressure/volume loops based on intratracheal pressure measurements during dynamic conditions;S.Karason et

10、 al, Acta Anesthesiol Scand 2000;44:571-577,Evaluation of pressure/volume loops based on intratracheal pressure measurements during dynamic conditions;S.Karason et al, Acta Anesthesiol Scand 2000;44:571-577,Tidal volume remains constant As I:E ratio is changed, autoPEEP is seen only with tracheal pr

11、essures PIP increases and Compliance decreases,TC,氣道阻力與流速的關系,7.5mm導管兩端壓力差,TC/ATC,ATC,Haberthur ICM 1999;25:514,Does the tube-compensation function of two modern mechanicalventilators provide effective work of breathing relief,Critical Care October 2003 Vol 7 No 5 Maeda et al,TC 100%, ETT 6.5mm,Pcirc

12、uit Peso Pplural,氣管壓力監(jiān)測,設計為間斷性監(jiān)測 更準確地顯示氣管內壓力 能夠監(jiān)測做功與阻力,Ptr (tracheal pressure) 作為壓力控制呼吸的向導,在壓力控制通氣時，由于氣管內插管造成的氣流阻力升高，導致肺內壓力達不到理想水平 AVEA可以測量氣管內壓力，并作為一條曲線顯示。 吸氣壓力可以根據氣管內壓進行調節(jié),Paw = 28 Ptr = 25,Ptr (tracheal pressure) 作為壓力控制呼吸的向導,用氣管壓和食道壓計算力學負擔,為何測量呼吸功,WOBpt 測定病人實際的呼吸功水平 正常 .3-.6 Joules/Liter .75 病人可能出

13、現(xiàn)疲勞 長期機械通氣病人脫機成功的關鍵是能否為他們提供一個正常的呼吸功 MacIntyre; Crit Care Med 1999; 27:1040 機器支持的力度應根據病人呼吸功來調節(jié) AVEA 可以提供此類數(shù)據,用氣管壓和食道壓計算力學負擔,用氣管壓和食道壓計算力學負擔,用氣管壓和食道壓計算力學負擔,2021/1/31,Real-time assessment of WOB,Effort is amplified by a factor of 4 with a proportionality ratio of 3:1,PAV+ Software Option Clinical Descri

14、ption,D. Georgopoulos, Intensive Care Med. 2008 Jul 8,Auto PEEP (Air Trapping,Static PEEPi End-Expiratory Hold,Problems with auto PEEP expiratory hold measurements,Will not work if patient is breathing spontaneously Will not work if patient has small airway closure, (flow dependent airways) False ne

15、gatives,1. Patient trigger work before PEEP applied,2. Note PEEP application,3. Patient trigger work after PEEP applied,監(jiān)測由于氣流受限而引起的內源性PEEP而增加的觸發(fā)功,F-V loop,F-V loop and leaking,漏氣,Leak,漏氣,SIMV+PSV，通氣管路存在漏氣,Auto PEEP,MIP 測量-定義,MIP (Maximum Inspiratory Pressure，最大吸氣壓) / P100 ，測量病人在自主呼吸狀態(tài)下，壓力曲線上的負向最大值,

16、MIP 測量-意義,正常值: 成人 -70 to -100 cm H2O 兒童 -20 to -100 cm H2O 脫機標準 -20 cm H2O 意義: 病人的呼吸力量參數(shù). 病人吸氣肌力量的標志物. 作為脫機以及評價神經肌肉疾病進展情況的標準. 在脊柱后側突，老年，COPD 以及神經肌肉疾病的病人會其絕對值會降低,P100 測量-定義,呼吸驅動 (P100), 探測到病人吸氣努力開始計算，第一個100 ms 內所形成的最大吸氣負壓,P100測量-正常值及意義,正常值: 成人-1 to -4 cm H2O 兒童-0.5 to -4 cm H2O 注意: 在吸氣已經啟動，而吸氣閥仍處于關閉狀

17、態(tài)的前100 ms所產生的壓力。 正常情況下，病人感知氣路阻塞所需要的時間為 300 ms ，因此，P100是一個很好的測量呼吸中樞驅動力信號的輸出指標。 在最初的這300 ms 時間里，肺容量和氣體流量沒有改變，因此，肺臟力學的異常對本指標的測量沒有影響。 超過 -5 cm H2O 意味著呼吸驅動過高，可能會增加呼吸功并導致呼吸肌疲勞,Intra-thoracic pressures while playing musical instruments,Trans-pulmonary Pressures,Esophageal balloon pressures reflect pleural

18、pressures Pleural pressures can indicate external pressures working against the lung Trans-pulmonary pressures can help us determine safe ventilation and effective PEEP,Numerical Assessments Paw, Pes, Ptp Insp 161:432439. R. SCOTT HARRIS, DEAN R. HESS, and JOS G. VENEGAS,Effect of the chest wall on

19、pressurevolume curve analysis of acute respiratory distress syndrome lungs,For most patients, the chest wall had little inuence on the total respiratory system P-V curve. However, there were patients in whom the chest wall did potentially have clinical signicance. （N=22, 23-77 yrs old,Dean R. Hess C

20、rit Care Med 2008 Vol. 36, No. 11,Dean Hess, et al,22 pts ALI/ARDS Chest wall compliance: 21462 ml/cmH2O,Dean R. Hess Crit Care Med 2008 Vol. 36, No. 11,Hickling K. AJRCCM 2001;163:69-78,Hickling K. AJRCCM 2001;163:69-78,最佳順應性 “ PEEP遞降測試法,肺復張趨勢圖 in Draeger LPP,Alveolar recruitment can be predicted from airway pressure-lung volume loops: an experimental study in a porcine acute lung i