Models of venous admixture.
نویسنده
چکیده
Medical students, residents, and allied health professionals often have difficulty quantitating ventilation-perfusion mismatch in ill patients. This manuscript quantitates ventilation-perfusion mismatch using the underlying physiological concepts and equations that describe mismatch. In addition, clinical problems with diagrams and worked-out solutions are supplied to help students master these equations as well as their practical limitations.
منابع مشابه
Dependence of pulmonary venous admixture on inspired oxygen fraction and time during regional hypoxia in the rabbit.
In order to examine the value of assuming constant pulmonary venous admixture with respect to changes in inspired oxygen fraction (FIO2) and time during sustained unilateral hypoxia, we studied venous admixture for 6 h in 27 anaesthetized rabbits in which the left lung was filled with liquid, isosmotic with plasma. In one group of 10 rabbits the right lung was ventilated for 6 h with FIO2 = 1; ...
متن کاملResponse of Pulmonary Venous Admixture*
T he efficacy of various types of pulmonary therapy is often questioned. This may stem from investigative methods. Evaluation of pulmonary gas exchange usually involves the determination of arterial oxygen tension (Pa02) and the calculation of the alveolar-to-arterial oxygen tension difference (P[Aa]O2), or pulmonary venous admixture, while pure oxygen is administered. Evaluation performed with...
متن کاملVenous Admixture in COPD: Pathophysiology and Therapeutic Approaches
Chronic obstructive and interstitial lung diseases impair pulmonary gas exchange leading to wasted ventilation (alveolar dead space) and wasted perfusion (venous admixture). These two fundamental types of abnormality represent opposite ends of the spectrum of ventilation-perfusion mismatch with V/Q ratios of infinity and zero. Treatment approaches that improve airway function, reduce air trappi...
متن کاملInspired oxygen fraction after cardiopulmonary bypass: effects on pulmonary function with regard to endothelin-1 concentrations and venous admixture.
Twenty consecutive patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) were allocated at random to group 1 (n = 10, high inspired oxygen fraction (FIO2) after CPB), or group 2 (n = 10, moderate FIO2 after CPB). The effects of each FIO2 on arterial and mixed venous concentrations of endothelin-1 (ET-1) and its precursor, Big ET-1, were measured. Venous admixture was calculated ...
متن کاملEffect of positive end-expiratory pressure on intrapulmonary shunt at different levels of fractional inspired oxygen.
In 10 patients undergoing ventilation, venous admixture was measured at different values of positive end-expiratory pressure (PEEP). The measurements were performed at the level of fractional inspired oxygen (FIO2) at which each patient was ventilated, and at FIO2=1. In patients ventilated at FIO2 between 0.21 and 0.3 venous admixture was not modified by PEEP, while in patients ventilated with ...
متن کاملEstimating venous admixture using a physiological simulator.
Estimation of venous admixture in patients with impaired gas exchange allows monitoring of disease progression, efficacy of interventions and assessment of the optimal inspired oxygen fraction. A pulmonary artery catheter allows accurate measurement, although the associated risks preclude its use solely for estimation of venous admixture. Non-invasive methods require assumed values for physiolo...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Advances in physiology education
دوره 25 1-4 شماره
صفحات -
تاریخ انتشار 2001