1226 
MONITORING 
like to look at data, and this information will be 
displayed. When several programs have been 
used to acquire the data on a given patient, it is 
necessary to limit the amount of data to be re- 
viewed. For instance, if pressure data and oxy- 
gen saturation data were obtained, it may be de- 
sirable to look at the time course of the oxygen 
saturation without the pressure data being dis- 
played. This option is available by specifying the 
program number of the desired data. 
It should be remembered that each of the 
above programs occupies one of the user areas 
on the computer, and at the present time, any 
three of these programs can be running simul- 
taneously on a time-shared basis. In addition, 
automatic monitoring of several animals can be 
continued under the control of AUTOMON. 
Automon 
This core resident program is nearing com- 
pletion and will acquire data from the animals 
at regular intervals of fifteen minutes. The op- 
eration of AUTOMON is shown in Figure 6. 
An animal can be logged on the automatic moni- 
tor by use of a special user program which can 
be called from the animal site. The log-on proce- 
dure includes entering the pertinent data for 
that animal : animal number, device number, 
and the programs to be used in evaluating the 
data. There will be a sixteen-program library 
available for use on AUTOMON, and any 
given animal can be assigned four of the sixteen 
programs for analysis. After the programs are 
selected, it will often be necessary to run a set 
of calibrations for the data used by those pro- 
grams. The programs which are used on the au- 
tomatic monitor are modifications of the user 
programs which have just been described. For 
instance, the Pressure program will be used but 
will have the capability of calculating the mean, 
maximum and minimum of at least four differ- 
ent pressures simultaneously. The trigger sig- 
nal is sampled and by use of a special small pro- 
gram is made available to all programs. For 
example, the trigger will be used not only by the 
Pressure program to perform its data reduction 
on the four pressures, but also by the Flow pro- 
gram. 
When the log-on procedure is complete and 
the information has been transferred to tables 
used by AUTOMON, the data from the animal 
will be monitored by use of an interrupt gener- 
ated by the time-of-day clock. Every minute, 
AUTOMON receives an interrupt and makes a 
check to see if there is any monitoring to be 
done. If a new patient has just been entered, 
then on the next interrupt, it will be sampled 
and will go through a full monitor period. This 
includes calculation of the data, a check for 
alarm conditions, and storage of data. The time 
controlling the sampling of the animal is then 
updated by fifteen minutes, at which time an- 
other sample will be automatically taken. 
The data reduction is carried out as shown in 
the bottom part of Figure 6. Any number of an- 
alog channels up to eight for any given animal 
are sampled at one time for a three-second pe- 
riod. Regardless of the number of beats during 
one sample period, the data is collected from 
each beat. The three-second sample period was 
selected to guarantee that at least one total 
heart cycle would occur during this period at 
heart rates down to forty beats per minute. 
Four different sample rates can be used for 
sampling the eight channels. At the end of the 
three-second sample period, Program 1 is called 
in and performs the calculations on the data as- 
sociated with that program. Program 2 is then 
called in and performs its data reduction. This 
process continues for the four programs which 
were selected for that animal and takes approx- 
imately 2.2 seconds. The data is then sampled 
again for a three-second period and the pro- 
grams are recalled to perform the data reduc- 
tion. This process continues until six sample pe- 
riods have occurred, at which time the average 
of all the variables calculated is taken. Then a 
program is loaded into memory which will 
check the variables for alarm conditions. 
From a standardized limit table which is 
stored on the disk, a special limit table is gener- 
ated depending on the variables selected for 
each animal at the time he is logged on the auto- 
matic monitor system. This table then provides 
the information for the alarm check. If the var- 
iables are outside the range specified and an 
alarm condition exists, an indicator is illumi- 
nated at the Main Monitor Console in the moni- 
tor room and the data is especially tagged for 
future reference. 
