Chapter-1 / Physiological Foundations - WHNLive Public Library

Uf}Qturetift,d.':H-r-t-t+A~+-1+-H++-+++-++W-+-H-+-~~::::j:+=l=+=P+~Jf++++~~~j:tt:t:ii:!::tt±±±±±±j~l±±±±f:B~lli, rt;-H++-l-+-+-t==1--..k:k+-+-~-+-w-+-w+m=+=u=+=u=+=u=+=::r:=r::J5 rt-r-H-t-+-iH-+-H---+=P*..,J-~-+-W-+-w-+-..r..+-+-W-1-W-+-W-1-W-J4rt;-H++-l-+-+-H-+-l-+~k+-+-W-+-w.....vW-l-W-l-W-l-W-I-W--J~t=t=++~~:t=t::t:4=t=t:tti::et±~H±fu:EEEHE3jxEE,H-rt-i-+-HH-+-H-+-+-+-+-l-+-+-W-+-W-f.-W-f.-W-I-W-I-W-+.-W-l6 O~1-;2~3~'-:5~6-:7~8~9:-:f}=-::11-:!12:-:B~14-:1'5::-~:l:-lS-.J.:17~'8':-19.L2.J.'O....J21L22L.l2J-2,L25L126....J27L18L29.LJ~L31LJ2.LJ33L3'L~.LJ36L37L38..LJ39"'"t ..Fig. 107 pH course in the myocardium of the left ventricle of a rat, showing the reversibility of tissue impairmentdue to 02 deficiency: pH renormalization after lifting the vascular occlusion as indicator. In another experimentof this type the blockade was not lifted after t = 24 min, but only after t =50 min, and did not return to normalCirrewrsible tissue damage, stop in microcirculation)hie or irreversible nature (cf. Fig. 95 above).Figure 107 shows an example of this. In thisregistration the pH drops from 7.7 to 6.3 afterthe vascular constriction, i. e. by 1.4 pH units,and quickly rises again to a normal level (7.3)after the vessel narrowing is lifted 22 min later.This shows how irreversible damage can beprevented and the metabolism of the tissuerestored, by eliminating early enough the disturbanceof supply. The restoration of the pHin the affected tissue area after the removal ofthe disturbing factor can be regarded as anindicator of the still reversible nature of thedamage.The duration of the phase in which the damageis still of a reversible nature (e.g. 25 min inmyocardiac infarction) is, according to WHOstatistics, only in 5 % of all cases longer thanthe time until the start of emergency medicalcare. It necessarily follows from this that onlythe patient himself (informed, prepared andsupplied with fast-acting drugs and, if necessary,also equipment) can aid himself effectively.When risk factors exist, it is therefore one ofthe most pressing duties of the physician dealingwith the case to equip the high-risk patient80 that the danger of irreversible 02 deficiencydamage is minimized (e.g. with the emergencypackage of "Strodival special", Fig. 87, .and, ifnecessary, also with 0.5 g methylpredmsolonefor risk of myocardial infarction, or with anoxygen carrier bag device for risk of strokec.). When irreversible damage has already ocerred,the natural timepoint for particularlye ective counter-measures ha passed.2 deficiency can have the mo t varied cau e ..of he e cau e i an inadequate -an thetl-zing technique (intensity and duration). Themeasurement in Fig. 108 shows the fast, substantialdrop in the pH in the cerebral cortexduring the death of a rat, caused by an overdoseof ether l2, 191]. We are dealing here witha very complex process, occurring in a largerconfluent tissue area, a process in which notonly O2 deficiency in the nerve tissue, but alsothe deficient situation and thereby labilizationof the blood-brain barrier [192], must play arole (see also Paragraph 1.4.10).Connection between volume of the 02-deficienttissue and amount of over-acidification.In the experiment in Figs 105 and 106 thevolume of the 02-deficient region in the myocardiumis V l'l:I 10 mm 3 (supply area of thenarrowed coronary vessel) after 3-12 min. ThepH drops to approximately 6.25. After t = 12min, i. e. after termination of artificial respiration,the deficiency volume spreads over thewhole heart, and a further steep drop in pH canbe detected in the registration. This findingleads us to the question of the influence of thevolume of the tissue affected by O2 deficienon the size of the pH reduction.Because the lactic acid formed by fermentationis quickly drained off the cell, th intra llularpH of a single glycolyzing cell hardI dr pbelow the level of the environment [191]. Hever, overacidification increa e rapidl ith increasingvolume V of th c 11 ongl m rati na can b s en from m a ur m nt n mi r ­meta ta of diff r nt iz [191). Th r I ti n-hip b tw n pH drop and lum f mi r -m ta ta con i ting f 1m t 100 fglycolyzing tumor 11 at n t nt I dgluco I v I f 4· 10- 3 glml i i n th