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HEMODYNAMICS. Dr . R. Tandon Sitaram Bhartia Institute, New Delhi. Pressures. RA : a = 2-6; V = 2-4 m = 3 (0-6) RV :15-25 edp 0-5. PA :15-25; diast. 6-10, m = 10-15. PAW : a = 6-12, V = 8-14, m 6-10 (12) LA (PV) : a=6-12, V=8-14, m = 6-10 (12) LV : 90-120 / 0-10 (12)
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HEMODYNAMICS Dr. R. Tandon SitaramBhartia Institute, New Delhi
Pressures RA : a = 2-6; V = 2-4 m = 3 (0-6) RV :15-25 edp 0-5. PA :15-25; diast. 6-10, m = 10-15. PAW : a = 6-12, V = 8-14, m 6-10 (12) LA (PV) : a=6-12, V=8-14, m = 6-10 (12) LV : 90-120 / 0-10 (12) SA :90-120 / 60-75 (70-85).
i) RA a = RV edp ‘a’ edp = TS ii) PA diast. = LA m. PA diast. LA (m) = PVR iii) PAW ‘a’ = LA ‘a’ = LV edp. iv) PAW ‘a’ (LA a) edp = obstr. (PV obstr, cortriat, MS, supra valv ring). Pressures
Oxymetry Oxygen Capacity (vol. %) Oxygen content (vol. %) Oxygen saturation (%) Vol % = ml O2 / 100 ml. Bl.
Oxygen Capacity 1 gm Hb can carry 1.36 ml O2. If Hb=15 gm : Capacity=15 x 1.36 =20.4 If Hb=10 gm : Capacity=10 x 1.36 = 13.6 Hence Hb must be determined for the calculation of O2 capacity.
Oxygen Saturation (%) % of oxygenated Hb. Obtained directly using oxymeters. Pulm. Ven. Sat. = 98% (100%). Arterial O2 Sat. = PV sat = 98-100%. Mixed ven. O2 Sat = 75-80% (PA). A drop of 2% or in arterial O2 sat. compared to PV Sat. = RL shunt
Oxygen Content O2 content = O2 cap x O2 sat./100. Hb 15 gm : Cap 15 x 1.36 = 20.4. SA Sat. 98%; MV Sat. = 80%, 60%. SA Content = 20.4 x 98 = 19.99 100 MV content = 20.4 x 80 = 16.32 100 MV content = 20.4 x 60 = 12.24 100
Oxygen Content • PO2 – 100 – O2content (room air) Hb Bound Dissolved 15 20.4 0.3 ml (1.5%) 10 13.6 0.3 ml (2.5%) • PO2 – 600 15 20.4 1.8 ml (9%) 10 13.6 1.8 ml (14%)
Cardiac Output • CO = Oxygen consumption (VO2) • (PV) SA O2 Cont.–MVO2 cont. x 10 • Oxygen consumption can be measures but is generally assumed depending on age, HR and BSA from nomograms. • O2 content needed to calculate flows.
Cardiac Output O2 content : (Hb 15) SA (98%) = 19.99 MV (80%) = 16.32 MV (60%) = 12.24 CD (1) = ____VO2______ = ___VO2___ 19.99 - 16.32 x 10 3.67 x 10 CO (2) = ______VO2_____= ___VO2___ 19.99-12.24 x 10 7.75 x 10
Cardiac Output i) CO = __VO2__ = __150___ = 4.08 l/m/M2 3.67x 10 3.67 x 10 ii) CO = __VO2___= __150___ = 1.93 l/m/M2 7.75 x 10 7.75 x 10 The lower the mixed venous O2 content (Or saturation) the lower the cardiac output.
Cardiac Output Qp) Pulm. Bl. flow = __________VO2___________ PV O2 Cont.–PA O2 Cont. x 10 Qs) Syst. Bl. flow = __________VO2___________ SA O2 cont.–MV O2 Cont. x 10 In the absence of a left to right or right to left shunt Qp = Qs
L R shunts Bl. Samples taken from PA, RV, RA, SVC ASD : SVC to RA Sets 1-10%, 2-7%, 3-5% VSD : RA to RV Set 1-7%, 2-5% PDA : RV to PA 1 set – 5%, 2-3%
L R shunts (Qs) Syst. Flow = __________VO2___________ SA O2 cont.–MV O2 Cont. x 10 (Qp) Pulm. flow = __________VO2___________ PVO2 Cont.–PA O2 Cont. x 10 QP – Qs = LR shunt.
Shunts Qp = ______VO2_______ PVO2 – PAO2 x 10 Qs = ______VO2_______ SAO2 - MVO2 x 10 L R shunt = Qp – Qs R L shunt = Qs – Qp
Shunts (Bidirectional) Qp = ___VO2__________ PVO2 – PAO2 x 10 Qs = ___VO2__________ SAO2 - MVO2 x 10 Qep = ___VO2__________ PVO2 – MVO2 x 10 L R shunt = Qp – Qep R L shunt = Qs – Qep
Shunt Ratio Qp / Qs = __SAO2– MVO2_ PVO2 – PAO2 Ratio can be estimated if saturation and Hb are known.
Resistance to Flow Systemic vasc. resistance (SVR) Pulmonary vasc, resistant (PVR) Dynes / sec. / cm-5 or Wood unit. 1 wood unit = 80 dynes / sec / cm-5. Always calculated as related to BSA. (Indexed)
Vasc. Resistance R = ___Delta P______ Q (l / m / M2) SVR = __Ao (m) – RA (m)_ Qs (l / m / M2) PVR = __PA m - LA m____ QP (l / m / M2) Normally PVR = 1 to 3 units SVR = 15-30 units