The role of the endothelin system in experimental acute lung injury

(1)

Thesis for doctoral degree (Ph.D.) 2006

The role of the endothelin system in experimental acute lung injury

Patrik Rossi

Thesis for doctoral degree (Ph.D.) 2006Patrik RossiThe role of the endothelin system in experimental acute lung injuryr

With special reference to the formation

of extra-vascular lung water

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

(24)

(25)

(26)

(27)

(28)

(29)

(30)

(31)

0DWHULDODQGPHWKRGV

The MDID method

The molecular double indicator dilution techniques for the assessment of EVLW are based on the simultaneous injection into a central vein of two indicators with different volumes of distribution. The diffusible indicator has a volume of distribution which LQFOXGHV ERWK WKH SXOPRQDU\ WLVVXH ZDWHU DQG WKH LQWUDYDVFXODU FRPSDUWPHQW ,Q

FRQWUDVWWKHQRQGLIIXVLEOHLQGLFDWRUKDVWKHVDPHYROXPHRIGLVWULEXWLRQDVSODVPDLH

WKHLQWUDYDVFXODUFRPSDUWPHQW

After injection in a central vein simultaneous and repetitive determination of the concentrations of the two indicators in arterial blood, provides time dependent curves of concentrations. These are separated in time if the volumes of distribution of the two indicators are different. By subtracting the volumes of distribution one can calculate the EVLW.

Molecular indicators used previously have been radioactively labeled and their concentrations determined by scintillation counting of serial blood samples collected in rotating cuvette holders. The method used in paper I is based on spectrometric analysis RI WKH QRQUDGLRDFWLYH VXEVWDQFHV LQGRF\DQLQH JUHHQ DQG GHXWHULXP KHDY\ ZDWHU

2H₂2%ORRGLVSXPSHGWKURXJKWKHGHWHFWRUV\VWHPIURPWKHDUWHULDOVLGHDQGEDFNWR

the venous side. ²H₂O is a suitable permeable indicator since it distributes in the same PDQQHUDVZDWHU,WLVQRQWR[LFLQWUDFHDPRXQWVDQGFDQEHGHWHFWHGVSHFWURPHWULFDOO\

The concentrations of the two indicators are determined 1,500 times every minute, resulting in smooth and precise time dependent concentration curves.

7RGHWHUPLQHWKHDUHDXQGHUWKHFXUYH$8&DQGÀRZIRUWKHLQGLFDWRUVWKHODVW

SRUWLRQ RI WKH GHFD\ LV VXEVWLWXWHG E\ 6WHZDUW+DPLOWRQ H[WUDSRODWLRQ^74,189, which DFFRXQWVIRUUHFLUFXODWLRQRIWKHLQGLFDWRUV7KHPHDQWUDQVLWWLPHGH¿QHGDVWKHSRLQW

in time, which divides the AUC in half, is determined for each curve as described by Zierler²²²¿J (9/: ZDV FDOFXODWHG DV WKH ÀRZ UDWH IRU²H₂O multiplied by the difference in mean transit times for the ICG and ²H₂O curves, and indexed to body weight to obtain EVLWI. At least two sets of curves were used to calculate a mean value for each measurement. The method has been described in detail earlier¹⁹⁹.

The indicator dilution curves for indocyanine green and ²H₂O were presented on a FRPSXWHUDQGFRUUXSWFXUYHVZHUHGLVFDUGHG&RUUXSWFXUYHVZHUHGH¿QHGDVVORZ

washout curves caused by very early recirculation causing a failure of the concentrations of the indicators to fall to at least one half of the peak concentration^25,29 which in turn JLYHVFXUYHVZLWKRXWDVHPLH[SRQHQWLDOGHFD\IRUPHDUO\UHFLUFXODWLRQFXUYHVZKLFK

KDYHDVHPLH[SRQHQWLDOGHFD\EXWZLWKHQODUJHGDUHDXQGHUWKHFXUYH¹⁷⁹WHFKQLFDOO\

distorted curves, i.e., signal distortion due to microbubbles of air or microthrombi.

(32)

The STID method

%\ XVLQJ VWDQGDUG HTXDWLRQV WKH VDPH FDOFXODWLRQV DV IRU WKH 0','PHWKRG WKH

V\VWHPFDOFXODWHVWKHÀRZQDQGWKHPHDQWUDQVLWWLPHt IRUWKHWKHUPDOLQGLFDWRU^189,222. When multiplying these two factors the system can determine the thermal distribution YROXPHEHWZHHQWKHVLWHRILQMHFWLRQDQGWKHWKHUPLVWRU7KLVYROXPHLVGHQRWHGLQWUD

WKRUDFLFWKHUPDOYROXPH,779¿JDQG(T,QDGGLWLRQWKHV\VWHPPHDVXUHVWKH

GRZQVORSWLPH'6WRIWKHORJDULWKPLFDOO\WUDQVIRUPHGGLOXWLRQFXUYH¿J

%\PXOWLSO\LQJWKH'6WZLWK(TWKHV\VWHPFDOFXODWHVWKHYROXPHRIWKH

ODUJHVW PL[LQJFKDPEHU LQ WKH VHULDO V\VWHP FRQVWLWXWHG E\ WKH KHDUW FKDPEHUV DQG

the lungs, according to Newman et al.¹⁴⁰. The largest mixing chamber for the thermal LQGLFDWRU LV GHQRWHG SXOPRQDU\ WKHUPDO YROXPH 379 DQG LV FRQVWLWXWHG E\ WKH

pulmonary blood volume and the lung tissue. By subtracting the PTV from the ITTV

35RVVL

Figure 6. Schematic illustration of the molecular double indicator dilution technique for the GHWHUPLQDWLRQRIH[WUDYDVFXODUOXQJZDWHU(9/:7KHGLVWULEXWLRQYROXPHIRULQGRF\DQLQHJUHHQLV

WHUPHGLQWUDWKRUDFLFEORRGYROXPH,7%9DQGLVGHSLFWHGZLWKJUH\GRWWHG¿OOLQJ7KHGLVWULEXWLRQ

YROXPHRIKHDY\ZDWHULVGHQRWHGLQWUDWKRUDFLFZDWHUYROXPH,7:9DQGLVGHSLFWHGLQJUH\¿OOLQJ

*UHHQDQGEOXHFXUYHVDUHGLOXWLRQFXUYHVIRULQGRF\DQLQHJUHHQDQGKHDY\ZDWHUUHVSHFWLYHO\7KH

UHGFXUYHVDUH6WHZDUW+DPLOWRQH[WUDSRODWLRQVGHULYHGIURPWKHRULJLQDOFXUYHGDWDEHWZHHQWKHUHG

´ÀDJV´0HDQWUDQVLWWLPHDQGÀRZDUHFDOFXODWHGDFFRUGLQJWRWKHDERYHHTXDWLRQVXVLQJFKDQJHVLQ

FRQFHQWUDWLRQ&DQGLQWHQVLW\,RYHUWLPHW+HQFH(9/:LVFDOFXODWHGDVWKHGLIIHUHQFHLQPHDQ

WUDQVLWWLPHIRUWKHWZRLQGLFDWRUVWLPHVWKHÀRZ5LJKWDWULXP5$ULJKWYHQWULFOH59SXOPRQDU\

EORRGYROXPH3%9OHIWDWULXP/$DQGOHIWYHQWULFOH/9

. -

Q .

°

d d

0 0

) (

dt t C

dt t C t t

°

d v

0

) ( dtt C t Q I

t

ICG

t

_H _O

2

ICG 2

t t

_H _O

2 2

v

$

t Q EVLW

ITBV ITWV EVLW _v

$

t Q EVLW

ITBV ITWV

EVLW

t

ICG

t

_H _O

2

ICG 2

t t

_H _O

2 2

v

$

t Q EVLW

ITBV ITWV EVLW _v

$

t Q EVLW

ITBV ITWV EVLW _v

$

t Q EVLW

ITBV ITWV EVLW _v

$

t Q EVLW

ITBV ITWV

EVLW

$t Q EVLW

ITBV ITWV EVLW ^-

. .

(33)

(34)

(35)

(36)

(37)

(38)

(39)

(40)

(41)

(42)

(43)

(44)

(45)

(46)

(47)

(48)

(49)

(50)

(51)

(52)

(53)

(54)

(55)

(56)

(57)

(58)

(59)

(60)

(61)

(62)

(63)

(64)

(65)

(66)

(67)

(68)

(69)

(70)

(71)