1、氧供需平衡麻醉氧供需平衡麻醉肺通氣肺通氣肺換氣肺換氣氧在血液中的運(yùn)輸氧在血液中的運(yùn)輸氧在組織中釋放氧在組織中釋放氧供需平衡麻醉 氧從空氣進(jìn)入細(xì)胞的線粒體內(nèi)要經(jīng)歷一系氧從空氣進(jìn)入細(xì)胞的線粒體內(nèi)要經(jīng)歷一系列過程，包括：肺通氣、肺換氣、氧在血液中列過程，包括：肺通氣、肺換氣、氧在血液中的運(yùn)輸及氧在組織的釋放四個(gè)步驟。也有學(xué)者的運(yùn)輸及氧在組織的釋放四個(gè)步驟。也有學(xué)者把氧運(yùn)輸過程中，從空氣中氧分壓把氧運(yùn)輸過程中，從空氣中氧分壓159mmHg 至細(xì)胞內(nèi)的至細(xì)胞內(nèi)的34mmHg的巨大落差形象地稱為的巨大落差形象地稱為氧瀑布。氧瀑布。氧供需平衡麻醉飽和蒸汽壓飽和蒸汽壓=47mmHgPiO2=(760-47)0

2、.2094=149mmHg氧供需平衡麻醉 v二氧化碳二氧化碳 - PACO2, 約等于約等于 PaCO2.vPAO2 = PIO2 PaCO2/R.- R 為呼吸商為呼吸商.- R 0.8.- PAO2 = 149 (40/0.8) = 100mmHg氧供需平衡麻醉w 氧從肺泡進(jìn)入肺靜脈氧分壓通常下降氧從肺泡進(jìn)入肺靜脈氧分壓通常下降 5 10 mmHg. PAO2=95mmHg氧供需平衡麻醉w 毛細(xì)血管和組織間液間的較大的氧分壓差毛細(xì)血管和組織間液間的較大的氧分壓差（ 30 mmHg）使得氧氣迅速由血液向組）使得氧氣迅速由血液向組織彌散織彌散。氧供需平衡麻醉氧供需平衡麻醉氧供需平衡麻醉w 1g

3、 血紅蛋白最多可結(jié)合血紅蛋白最多可結(jié)合1.34ml的氧氣。的氧氣。 (1.39ml when the hemoglobin is chemically pure)w 如果如果 Hb=15g/100ml, 最大結(jié)合的氧量最大結(jié)合的氧量 =15*1.34=20.1ml/100ml氧供需平衡麻醉w 動(dòng)脈血?jiǎng)用}血: SaO2=97%, CaO2=19.4ml/100mlw 混合靜脈血混合靜脈血: PvO2=40mmHg, SvO2=75% CvO2=14.4ml/100mlw C(a-v)O2=19.4-14.4=5ml/100ml氧供需平衡麻醉utilization coefficient/oxyg

4、en extraction）w The percentage of the blood that gives up its oxygen as it passes through the tissue capillaries is called the utilization coefficient.-normal value is about 25%.-during exercise, can increase to 7585%.氧供需平衡麻醉The normal relationship is for a 4:1 ratio between DO2 and VO2. or in CO an

5、d DO2 do not affect oxygen consumption.氧供需平衡麻醉w Relationship between DO2 and VO2 seen in critically ill patients, when increases in CO or increases in oxygen delivery, result in parallel increases in VO2.氧供需平衡麻醉氧供需平衡麻醉氧供需平衡麻醉Alkalosis the Bohr effectHypothermiaAbnormal and fetal HbCarboxyhemoglobin,

6、 MethemoglobinDecreased 2,3-diphosphoglycerate氧供需平衡麻醉Increased hydrogen ionsIncreased CO2Increased temperatureIncreased 2,3-diphosphoglycerate (DPG)氧供需平衡麻醉w DO2 是每分鐘供給機(jī)體的氧量。是每分鐘供給機(jī)體的氧量。 w DO2=(0.0031PaO2+1.34HbSaO2)COw DO2=1.34HbSaO2CO如果如果CO=5L,Hb=15g，DO2=1.3415015=1005ml/L氧供需平衡麻醉 VO2=CO(CaO2-CvO2)(

7、ml/min) 正常情況下，正常情況下， 200250ml/min.氧供需平衡麻醉氧供需平衡麻醉w CO.w 血流再分布血流再分布.w 細(xì)胞攝氧率細(xì)胞攝氧率.氧供需平衡麻醉Monitoring?理想部位：線粒體難點(diǎn)：細(xì)胞內(nèi)的氧合狀況無法直接監(jiān)測思路：對氧輸送過程進(jìn)行監(jiān)測氧供需平衡麻醉測定測定Hct及及Hb的方法的方法全血細(xì)胞分析儀全血細(xì)胞分析儀- Hct、Hb血?dú)夥治鰞x血?dú)夥治鰞x Hct、Hb血紅蛋白分光光度儀血紅蛋白分光光度儀- Hb離心機(jī)離心機(jī)Hct氧供需平衡麻醉SpO2 monitored by Pulse oximetry since 1980 SO2=O2Hb/(O2Hb+HHb)(

8、%)If R940/R660=1, SO2=85%氧供需平衡麻醉Two types oximetry: 氧供需平衡麻醉反射式脈搏氧飽和度探頭反射式脈搏氧飽和度探頭氧供需平衡麻醉The esophageal probe (ESOX, ARISTO Medical, Chicago, IL)氧供需平衡麻醉 PO2 is to measure directly from a blood sample, usually by using a Clark electrode. PCO2 electrodes work by measuring the change in pH induced when

9、blood equilibrates with a potassium chloride/sodium bicarbonate solution. 氧供需平衡麻醉氧供需平衡麻醉氧供需平衡麻醉連續(xù)頸內(nèi)靜脈血氧飽和度監(jiān)測連續(xù)頸內(nèi)靜脈血氧飽和度監(jiān)測氧供需平衡麻醉經(jīng)氣管混合靜脈血氧飽和度監(jiān)測經(jīng)氣管混合靜脈血氧飽和度監(jiān)測氧供需平衡麻醉術(shù)中常用的術(shù)中常用的CO監(jiān)測方法監(jiān)測方法w 右心飄浮導(dǎo)管w Piccow (外周動(dòng)脈) FloTrac 傳感器w TEE氧供需平衡麻醉由動(dòng)脈壓力波形計(jì)算由動(dòng)脈壓力波形計(jì)算COCO = HR * Sd(AP) * 氧供需平衡麻醉PiCCOwUsing PiCCO typica

10、lly requires insertion of a thermodilution catheter in the femoral or axillary artery instead of a standard arterial line. Any available central venous catheter can be used to inject the solution for the thermodilution analysis.氧供需平衡麻醉術(shù)中術(shù)中TEE測量測量COw M型法短軸縮短率： FAC=(EDA-ESA)/EDA ; 自動(dòng)邊緣識別系統(tǒng)（ABD）w 二維Sim

11、pson法 SV=LVEDV-LVSDV w 多譜勒法 SV=時(shí)間速度積分X橫截面積 w 三維法 氧供需平衡麻醉氧供需平衡麻醉Calculation of the shunt fractionw Qt = total cardiac output w Qs = shunted portion of cardiac output w Qns = normal pulmonary end-capillary blood flow that is not shunted past abnormal alveoli w Qt = Qs + Qns w or Qns = Qt - Qs 氧供需平衡麻醉C

12、alculation of the shunt fractionw Qt (CaO2) = total oxygen delivered to the body (DO2) w Qs (CvO2) = oxygen content of shunted blood w Qns (CcO2) = oxygen content of end-capillary blood Total oxygen delivered equals the sum of oxygen in both shunted and non-shunted blood w Qt (CaO2) = Qs (CvO2) + Qn

13、s (CcO2) 氧供需平衡麻醉Calculation of the shunt fractionSubstituting (Qt - Qs) for Qnsw Qt (CaO2) = Qs (CvO2) + (Qt - Qs)(CcO2) w Qt (CaO2) = Qs (CvO2) + Qt (CcO2) - Qs (CcO2) w Qs (CcO2 - CvO2) = Qt (CcO2 - CaO2) The intrapulmonary shunt equationw Qs/Qt = CcO2 - CaO2 /CcO2 - CvO2 氧供需平衡麻醉w SvO2 60%80%w Oxy

14、gen extraction ratio (O2ER) O2ER=(CaO2-CvO2)/CaO2w Lactic acid 7.32氧供需平衡麻醉wGastric tonometry determines intraluminal PCO2 which is assumed to be in equilibrium with PCO2 in the gastric mucosa. Intramucosal pH (pHim) can be calculated by the Henderson-Hasselbach equation using the PCO2 value determin

15、ed by gastric tonometry and the bicarbonate concentration in arterial blood.oBaigorri et al. Critical Care 1997 1:61 doi:10.1186/cc104氧供需平衡麻醉決定決定DO2與與VO2的因素的因素DO2VO2HbSaO2COSvO2HbCOSaO2.氧供需平衡麻醉術(shù)中影響氧供的因素術(shù)中影響氧供的因素DO2CO/Hb100%50%25%氧供需平衡麻醉缺氧缺氧w 低氧血癥：PaO260mmHgw 缺氧類型Hypotonic anoxiaAnemic anoxiaCirculat

16、ory anoxiaHistogenous anoxia氧供需平衡麻醉 氧治療氧治療wControlled oxygen treatment is used in those who need supplemental oxygen but not rely on their hypoxic drive to continue breathing.-an increase in PaCO2 show they rely on hypoxic drive. 氧供需平衡麻醉 (1) Give oxygen as much as you can at first, and then reduce it, guided by blood gas measurements.(2) Oxygen treatment will work only if the patient has a patent airway and is breathing. (3) Definitive treatment of hypoxia depe