生物醫(yī)學(xué)測量與儀器-展示頁
2025-01-13 14:17本頁面
【正文】 和 Ti是冷生理鹽水的注入量（升）和溫度（ ℃ ）， Tb是注入冷生理鹽水前的血液溫度（ ℃ ）， Tb’ 是注入后在測溫點(diǎn)的血液溫度。 熱稀釋法 四腔導(dǎo)管 SwanGanz漂浮導(dǎo)管（四腔：血壓、指示劑、溫度傳感器、漂浮氣囊） ? 熱稀釋采用冷生理鹽水作為指示劑，具有熱敏電阻的SwanGanz漂浮導(dǎo)管作為心導(dǎo)管。 ? 連續(xù)輸注指示劑 —— 稀釋法 ? 快速輸注指示劑 —— 染料稀釋法 阻抗法 成像法：超聲、磁共振 心輸出量測量 HRSVCO ?? 連續(xù)輸注指示劑 —— 稀釋法 二、指示劑稀釋法 CdtdmdtdVF???/① When a given quantity m0 of an indicator is added to a volume V, the resulting concentration C of the indicator is given by C=m0/V. ② When an additional quantity m of indicator is then added, the incremental increase in concentration is △ C=m/V. ③ When the fluid volume in the measurement space is continuously removed and replaced, then in order to maintain a fixed change in concentration, the clinician must continuously add a fixed quantity of indicator per unit time .That is △ C=(dm/dt)/(dV/dt) Fick Technique（費(fèi)克技術(shù)） va CCdtdmF??/F = blood flow, L/min dm/dt = consumption of O2, mL/min Ca = arterial concentration of O2, mL/L Cv = venous concentration of O2, mL/L Attention: ① In the Fick method, the indicator is O2. ② We cannot accurately measure Cv in the right atrium. We must measure it in the pulmonary artery after it has been mixed by the pumping action of the right ventricle. ③ We can measure the concentration of the oxygenated blood Ca in any artery. Thermodilution（熱稀釋法） TcqFbb ???q = rate of heat added, W ρb = density of the blood, kg/m3 cb = specific heat of the blood, J/ △ T = temperature change, K ?The best promise is to inject the heart into the right atrium and— after the heat has been mixed with normal blood in the right ventricle — to sample the resulting mixture in the pulmonary artery. 快速輸注指示劑稀釋法 ① An increment of blood of volume dV passes the sampling site in time dt. ② The quantity of indicator dm contained in dV is the concentration C(t) times the incremental volume. Hence dVtCdm )(?③ Dividing by dt, we obtain dtdVtCdtdm /)(/ ?④ But dV/dt=Qi, the instantaneous flow, therefore dttCQdm i )(?⑤ Integrating over time through t1, when the bolus has passed the downstream sampling point ,we obtain ?? 10 )(t i dttCQm⑥ Minor variations in the instantaneous flow Qi produced by the heartbeat are smoothed out by the mixing of the bolus and the blood within the heart chambers and the lungs. Thus we can obtain the average flow Q from ??10)(tdttCmQ? 熱稀釋法是較常用的心輸出量監(jiān)護(hù)法。 一、心輸出量 心臟每分鐘射出的血量 ,是衡量心功能的重要指標(biāo)。 當(dāng)袖帶壓力降到舒張壓時(shí)，血流速度快，可以認(rèn)為袖帶 1和 2的搏動(dòng)幾乎同一時(shí)間。 當(dāng)袖帶緩慢放氣達(dá)到收縮壓時(shí)，兩袖帶下都開始出現(xiàn)搏動(dòng)。 當(dāng)袖帶壓力減小時(shí)，開放和閉合之間的時(shí)間間隔增加，直到脈搏的閉合信號(hào)與下一次脈搏的
教學(xué)課件相關(guān)推薦
鄂ICP備17016276號(hào)-1