Chapter-1 / Physiological Foundations - WHNLive Public Library

Basic mechanisms and functions 11e duration time for the high-charging of adowngraded microcirculation (detumescencetime) is determined by the therapeutically appliedP02 level at the venous capillary end.The O2 supply of the endothelial cells at thecapillary end by means of diffusion is dependenton this. From the measurements oft~s in Fig. 3 (guiding values) it emerges that,WIth the procedure variant with increase incardiac output by means of severe physicalexertion and P02-ven = 60 mmHg (8 kPa) thethreshold for high-charging will be crossed withsufficient certainty in 15 min; with the procedurevariant without increase in cardiac output,and P02-ven = 45-50 mmHg (6-6.6 kPa) inapproximately 36 h.The aforementioned P0 2 - ven levels are attainedusing the standard 15 min O 2 multistep qUickprocedure discussed below, and the standard36 hl18 day O 2 multistep procedure.From the theory of diffusion and from experimentalexperiences there results the followingrelationship for the effectiveness W of O 2multistep therapy procedures and of proceduresof hyperbaric O 2 multistep therapy:W......(Po 2 _ven procedure - Po2-ven before)n • tprocedureKey:P0 2 -ven procedure = venous Po 2 , measured duringprocedure with O2 application.This value is dependenton the arterial P0 2during the procedure andthe bloodflow Q in the capillaries.The Q-Ievel is roughlyproportional to the cardiacoutput and therefore approximatelytwice as highduring the 15 min procedureas in the 36 h procedure.The strength of themicrocirculation thereforehas a significant influenceon the triggering of theswitching mechanism. 1P02-ven before= venous Po 2 , measured beforeproceduren= efficiency exponent llIS 3.5;emniricallv obtained fromtprocedurethe measured value in ig.3 2 and the relationship ofthe duration of procedures= total duration of the 02MTprocedureIf, due to the named procedure variants or dueto their reversal in the direction of "02 deficiencyconditions over a certain length oftime", the oxygen partial pressure simultaneouslychanges at the venous end of all capillariesof the organism over a certain time span,a comprehensive effect occurs. It can be measuredabsolutely by spirometry as a change inthe resting O2 uptake or CO2 production of theorganism. Relative values of this change can begained from changes in the arterial and venousresting P0 2 (see Section 1.1.5).In the framework of the application of the02MT it is usually only the total effect that isconsidered in the judgement of the O2 situationand its dynamics. A more detailed evaluationwas made in [35].It is known that the O 2 utilization variesgreatly, dependent on the rate of O 2 consumptionin the individual organs and tissues. Thishas as a result that the venous P0 2 of the variousorgans and tissues shows great differences.The scale of P02.ven levels for normal youngpersons, resting, is given in Fig. 5 B, bottomrow. It reaches 22 mmHg (heart) to 68 mmHg(spleen). The mixed blood carried to the lunghas a resting P02-ven level of 40 mmHg, withphysical rest and compensated cardiac output.It is known that the mixed P0 2 - ven at rest decreasesto roughly 35 mmHg in old age [35].The reduction is obviously a counter-regulationof nature, to counter the severe drop of thearterial resting P0 2 in old age [37]. Correspondingto the reduction of the mixed P0 2 - ven of anaverage 5 mmHg at an age of 75 years roughlythe same reduction of the resting P0 2 - ven levelassigned to the organs and tissues occur . Thescale of the expected resting P0 2 - ven level forolder, untreated persons is given in Fig. 5 B toprow.The O 2 supply to the endothelial cell at thevenous capillary end depends on the level of thevenous O2 partial pressure. A high P0 2 • ven resultswhen a high arterial O 2 partial pre ure i1 The effect contribution of the optional adjuvant tep ofHOT- and hemodilution i mainly reflect d in an increaof blood flow Q.2 P. = 45 mmHg as umed for the 36 h procedur02-ven procedure