A MODEL FOR CLOSED THORACIC OBSERVATION 
OF THE PULMONARY MICROCIRCULATION IN SHOCK 
W. A. Cook, P. B. Speiller, H. Sherman and S. K. Klausner* 
The design, preparation, and use of a lucite mem- 
brane thoracic window for incident-light, dark-field, 
cinemicroangiology is presented. The usefulness of this 
method of in vivo microvascular study for solid and 
transparent organs during low-flow states is described. 
INTRODUCTION 
It has been pointed out by several authors that 
physiologic study of the pulmonary microvas- 
culature is best performed through an air- 
tight thoracic window.-'^'^ Ingenious devices 
have been developed to this end for over 50 
years.^'^ '^'^ Most recently an extremely nonreac- 
tive windov^^ has been described by Krahl con- 
sisting of a double flanged lucite bobbin and a 
j window of 0.5 mil FEP teflon film stretched 
over the inner surface of the bobbin.* 
We are using a method of microsvascular 
investigation that employs the metallurgical 
microscope. A set of epiobjective lenses are 
coupled with the system to deliver light 
through the microscope itself. This light which 
obviates the need for tissue transillumination 
can be delivered in a bright or dark-field mode. 
We have found dark-field illumination most 
satisfactory. The new method of microscopic 
i technique required our modifying the thoracic 
' window and the support of the microscope.^ 
METHOD 
First of all we wished to observe any gravity 
related intravascular phenomena and there- 
fore decided to arrange our equipment to view 
the vessels from the horizontal aspect (Fig. 1). 
This required a special mount carrying the light 
source, microscope, and cameras (still and 
cine) . This mount is so arranged that this 40 
to 50 pounds of equipment all moves with the 
microscope when either its coarse or fine focus 
* Albert Kinstein College of Medicine, Bronx, New York. 
is changed. We utilize a xenon burner which 
provides light at 6000° Kelvin and has roughly 
the same spectrum as sunlight. 
For open thoracic work in acute experiments 
we use a pylon containing a large diameter cover 
slip against which the organ is pressed for ob- 
servation. However, as pointed out, physiologic 
study of the pulmonary vasculature is best done 
through an airtight thoracic window."'^'^''^'^ The 
mount shown in Figure 1 is a part of our sys- 
tem for study.-''' The basic requirements in con- 
struction of a new thoracic window adapted to 
this system of incident dark-field illumination 
were three. First, any interposed material be- 
tween the tissue and the objective lens must 
have a high degree of polish at its air or outer 
interface. This is essential in order to prevent 
back-scatter of the incident light which in turn 
reduces tissue illumination. The second require- 
ment is that this interposed material be plane 
to a surface perpendicular to the axis of ob- 
servation. This assures minimal distortion and 
more even tissue illumination. The last require- 
ment is limitation of tissue motion. Peculiar to 
this high magnification (450X), incident-light 
system is an optical tolerance to slow lateral 
tissue motion. Marked blurring of the field of 
view only occurs when there is motion along 
the axis of observation, and we therefore sought 
to eliminate this motion. 
We were interested in developing windows 
which met these three requirements and were 
also suitable for study of various size laboratory 
animals. Our point of departure was Krahl's 
lucite bobbin-teflon membrane window.* This 
design failed to provide limitation of motion 
along the axis of observation due to the flexible 
teflon membrane, or a means by which the 
window could be rigidly stabilized at right 
angles to that axis. 
Our first modification was to mill a thread 
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