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SPONTANEOUS VENTILATION DURING SURGICAL ANAESTHESIA IN THE CANINE
SPONTANEOUS VENTILATION DURING SURGICAL ANAESTHESIA I N THE CANINE
M.A.
Camburn
Royal (Dick) School of V e t e r i n a r y S t u d i e s Edinburgh
The c o r r e c t a d m i n i s t r a t i o n of v o l a t i l e a n a e s t h e t i c s r e q u i r e s a knowledge o f such r e s p i r a t o r y parameters as t h e t i d a l volume (T.V.), t h e minute volume ( M . V . )
and t h e r e s p i r a t o r y r a t e (R.R.),
especially i n
a n a e s t h e t i c systems where t h e r e must b e no r e - b r e a t h i n g of t h e expired gases.
To e s t a b l i s h g u i d e l i n e s for t h e s e parameters and t o g i v e
s t u d e n t s a g r e a t e r awareness of t h e s e measurements, t h e s t u d e n t s on a n a e s t h e t i c duty i n t h e Small A n i m a l Department are asked t o r e c o r d t h e s e parameters a t t e n minute i n t e r v a l s d u r i n g t h e a n a e s t h e t i c p e r i o d . Wrights and R . R .
A
s p i r o m e t e r i s used t o c a r r y out t h e s e r e c o r d i n g s of M.V.,
T.V.
I n a d d i t i o n t h e d e t a i l s of t h e a n a e s t h e t i c t e c h n i q u e , t h e
gas flow r a t e s and c o n c e n t r a t i o n s , plus t h e d e t a i l s of t h e s u r g e r y and t h e d e t a i l s of t h e p a t i e n t a r e a l s o recorded.
I n e s t a b l i s h i n g t h e g u i d e l i n e s f o r f u t u r e undergraduate t e a c h i n g
I c o l l a t e d t h e d a t a from t h e l a s t 50 c a s e s recorded i n t h e waj- d e s c r i b e d . The information was processed w i t h t h e a i d o f a P.D. 1 2 l a b o r a t o r y The r a w d a t a from
computer u s i n g s t a n d a r d s t a t i s t i c a l programmes. t h e s e 50 cases i s swnmarised i n t a b l e 1.
As you can s e e , f o r t h i s
t h e mean average
c a n i n e p o p u l a t i o n w i t h a mean body weight o f 25 Kgms.
minute volume is 5.4L, t h e mean average t i d a l volume i s 269.8 mls. and t h e mean r e s p i r a t o r y r a t e i s 21.4 p e r minute. compared w i t h t h o s e of P i c k r e l l beagles which weighed between R e s p i r a t o r y Rate 24
4.
values i n dogs weighing
e t al.
25 p e r m i n .
T.V.
220
5 47, with a
Hanlin and Smith recorded t h e following
202.47 m l s R . R .
found i n dogs of body weight of 10
-
f o r 39 conscious s t a n d i n g
6 and 1 1 . 5 Kgms
7 - 33 Kgms. which had been a n a e s t h e t i s e d with
sodium p e n t o b a r t i t o n e T.V.
15
These values can b e
- 14
Kgms
13.56 p e r mn
. T.V.
125
-
and Raventos 250 rnls
R.R.
when t h e y were a n a e s t h e t i s e d with Halothane.
It i s f a i r l y obvious t h a t t h e s e parameters must be r e l a t e d t o
t h e s i z e of t h e pat i en t .
It w a s decided t o i n v e s t i g a t e t h e r e l a t i o n -
s h i p between t h e s e parameters and t h e body weight of t h e s u b j e c t . The body weight w a s s e l e c t e d as t h e most convenient measurement of body
s i z e under c l i n i c a l c o n d i t i o n s , e s p e c i a l l y as t h e m a j o r i t y of dogs a r e weighed p r i o r t o a n a e s t h e s i a .
Table 2 summarises some o f t h e
r e l a t i o n s h i p s t h a t were s t u d i e d by r e g r e s s i o n a n a l y s i s .
The r e l a t i o n -
s h i p s t h a t g i v e t h e most s i g n i f i c a n t curves a r e t h e s e where t h e l o g of o r t h e l o g of T.V. are p l o t t e d a g a i n s t t h e l o g of body weight.
M.V.
The curves of t h e s e r e l a t i o n s h i p s are i l l u s t r a t e d i n figures 1 and 2 respectively.
Three d i f f e r e n t a n a e s t h e t i c systems were used d u r i n g t h i s s t u d y ; t h e Magill on 24 o c c a s i o n s , a t o and ' f r o system on 20 o c c a s i o n s , and a c i r c l e system on
6 occasions.
I t h e n decided t o s e e i f t h e r e was any
d i f f e r e n c e between t h e systems where r e b r e a t h i n g is p e r m i t t e d and t h e There were small b u t none s i g n i f i c a n t changes i n t h e s l o p e s
Magill.
of t h e r e l a t i o n s h i p s b u t i n t h e c a s e o f t h e r e l a t i o n s h i p s between body weight and T.V. and M.V.
(P
0.01 and
P
t h e slopes a r e displaced s i g n i f i c a n t l y
0.001 r e s p e c t i v e l y )
as shown f o r M.V.
i n f i g . 3.
This o b s e r v a t i o n i s probably r e l a t e d t o a n i n c r e a s e i n dead space i n t h e r e b r e a t h i n g systems.
Another s i g n i f i c a n t o b s e r v a t i o n w a s t h e i n c r e a s e of t h e M.V. with t i m e following t h e i n d u c t i o n of a n a e s t h e s i a . cases were induced w i t h t h i o p e n t o n e sodium 2 . V .
The m a j o r i t y of
and maintained on
Halothane, n i t r o u s oxide and oxygen gas m i x t u r e s .
This i n c r e a s e
becomes h i g h l y s i g n i f i c a n t i f t h e immediately post i n d u c t i o n readings a r e compared t o t h o s e at t h e p o i n t where t h e a n a e s t h e t i c i s terminated
a t t h e completion of s u r g e r y b u t p r i o r t o t h e removal of t h e e n d o t r a c h e a l tube.
I n t h i s s e r i e s I could f i n d no s i g n i f i c a n t i n f l u e n c e o f such f a c t o r s as, age, s e x , t y p e of s u r g e r y , p o s i t i o n i n g of t h e p a t i e n t , on t h e p a t t e r n of v e n t i l a t i o n of t h e dogs s t u d i e d .
23
Conclusion Using t h e d a t a accumulated from t h e f i f t y cases s t u d i e d a guide l i n e f o r s e t t i n g gas flows i n non r e b r e a t h i n g a n a e s t h e t i c systems can b e based on t h e formulae minute volume equals 3 l i t r e s p e r minute + This formula i s based on t h e upper
140 m l s p e r kilogram p e r minute.
99% confidence l i m i t l i n e on t h e log body w e i g h t , a g a i n s t l o g min. volume curve.
Fig.
L shows t h e l i n e from t h i s s e r i e s of dogs of t i d a l
volume compared with t h o s e of M i t c h e l l f o r p i g s , h o r s e s , sheep and c a t t l e . The l i n e l a b e l l e d S t a h l i s drawn from t h e equation o f S t a h l ’ s
i n his
review of t h e s c a l i n g of v a r i o u s p h y s i o l o g i c a l parameters from shrews and whales. Anaesthesia i s known t o cause a d e c r e a s e i n r e s p i r a t o r y H a l l found a 15% d e c r e a s e i n minute volume i n l i g h t
performance.
Similar
a n a e s t h e s i a and a 60% d e c r e a s e i n deep a n a e s t h e s i a i n man.
observations i n dogs by Raventos, H a l l , Hall Morris and Markil and
It i s worth n o t i n g t h a t t h e values from t h i s s e r i e s are
Eger.
15 -
;?o$
lower when compared w i t h t h o s e of P i c k r e 1 1
f o r t i d a l volume
and r e s p i r a t o r y .
REFERENCES Dobkin, A . B . , Fedoruk, S. (1961) Anesthesiology, H a l l , L.W.
(1957)
H a l l , K.D.,
Hanlin, R.L.,
V e t . Rec.
N o r r i s , F.H. Smith, C . R .
(1958) (1967)
69:
355.
22:
615.
Anesthesiology.
19:
h e r . J. V e t . Res.
339. 28:
173.
M i t c h e l l , B. (1972) Proceedings o f t h e A s s o c i a t i o n of V e t e r i n a r y A n a e s t h e t i s t s of G.B. and I r e l a n d No. 3. 56. P i c k r e l l , J . A . e t al., (1971) Lab. Animal Science, Raventos, J. (1956) S t a h l , W.R.
(1967)
B r i t . J. Pharmacology. J . Applied Physiology.
21r
11: 394 22:
453.
21:
677.
TABLE 1
SUMMARY OF ACCUMULATED RAW DATA
Values shown i n ( ) a r e t h e s t a n d a r d d e v i a t i o n f o r t h a t p a r t i c u l a r value
Factor
Combined (A+B)
Absorber systems (A),
Magill ( B )
26 30.7 K g m . (9)
24 19.0 K g n s (8.2)
25.0 K g m s . (10.4)
6.6 l i t r e s (2.6)
4.2 l i t r e s (1.9)
5.4 l i t r e s (2.6)
218.9 m l s (83.9)
250.5
234. m l s ( 107.4)
316.3 d s (108.4)
219.0
A v . T i d a l Vol./Kgm-
11.7 m l s (4.1)
12.6 mls (4.4)
11.8 m l s (4.0)
Av. R e s p i r a t o r y Rate
21.5
21.3 (8.8)
21.4 (8.7)
No. o f cases
Av. body weight Av. Minute Volume
.
Av Min .Volume/KgmA v . T i d a l Volume
(8.7)
TABm 2
mls
( 217.9 d s
(121.5)
50
269.8 m l s (124.8)
RELATIONSHIPS EXAMINE3 Significance
Equation
2.0581 + 0.1346 body weight Min. Vol/Kgm. = 343.604 - 4.3707 body weight Min.Vo1. = 6.4376 l o g body weight - 3.2994 = 0.5951 l o g body weight - 0.121 Log.Min.Vo1. Max.Min.Vo1. = 4.6375 + 0.1465 body weight T i d a l volume = 81.6991 + 7.5071 body weight T i d a l volume/Kgm = 15.0123 - 0.1268 body weight T i d a l volume = 375.21 l o g body w g t . - 238.965 Log t i d a l volume - 1.3999 + 0.7243 l o g body weight R e s p i r a t o r y weight = 23.8902 - 0.Og98 body weight Min. Vol. =
25
p i 0.001 p < 0.01 p < 0.001
p< 0.001 p< 0.025 p< 0.001
p< 0.025 p< 0.001 p< 0.001 p< 0.1
#
0 8 #
4
10
# 0 0 0 0
8
i: F i g u r e 1.
..--
u -
The solid l i n e r e p r e s e n t s t h e r e l a t i o n s h i p d e f i n e d by t h e e q u a t i o n log Minute Volume = 0.5951 log body w g t .
-
0.121.
The d o t t e d l i n e r e p r e s e n t s t h e 99% c o n f i d e n c e limits of this line.
body wgt Figure 2 .
The s o l i d l i n e r e p r e s e n t s t h e r e l a t i o n s h i p defined by
t h e equation l o g . T i d a l Volume = 1.3993 body wgt.
+ 0.7243
m e d o t t e d l i n e s r e p r e s e n t t h e 99%
confidence limits f o r t h i s l i n e .
27
log
Figure 3.
The r e l a t i o n s h i p f o r Min. Volume and body wgt. a r e compared f o r systems designed t o be non
r e b r e a t h i n g ( n . r . ) and when
r e b r e a t h i n g i s p e r m i t t e d ( r ) due t o t h e presence of a carbon dioxide s u b s c r i b e r .
28
TIDAL VOL. 3L
2 -1
Figure
4. The s e r i e s of l i n e s s h a m a r e t h e r e l a t i o n s h i p of t i d a l volume t o body w g t . i n a number o f s p e c i e s .
The l i n e s
for h o r s e s ( h ) p i g s ( p ) c a t t l e ( c ) and sheep ( s ) are t h o s e of M i t c h e l l . t h i s project.
The l i n e f o r dog i s t h a t e s t a b l i s h e d i n The l i n e l a b e l l e d S t is t h e l i n e based on
t h e r e l a t i o n s h i p d e f i n e d by S t a h l i n h i s work on s c a l i n g o f various r e s p i r a t o r y parameters.
M.A.
Camburn
Royal (Dick) School of V e t e r i n a r y S t u d i e s Edinburgh
The c o r r e c t a d m i n i s t r a t i o n of v o l a t i l e a n a e s t h e t i c s r e q u i r e s a knowledge o f such r e s p i r a t o r y parameters as t h e t i d a l volume (T.V.), t h e minute volume ( M . V . )
and t h e r e s p i r a t o r y r a t e (R.R.),
especially i n
a n a e s t h e t i c systems where t h e r e must b e no r e - b r e a t h i n g of t h e expired gases.
To e s t a b l i s h g u i d e l i n e s for t h e s e parameters and t o g i v e
s t u d e n t s a g r e a t e r awareness of t h e s e measurements, t h e s t u d e n t s on a n a e s t h e t i c duty i n t h e Small A n i m a l Department are asked t o r e c o r d t h e s e parameters a t t e n minute i n t e r v a l s d u r i n g t h e a n a e s t h e t i c p e r i o d . Wrights and R . R .
A
s p i r o m e t e r i s used t o c a r r y out t h e s e r e c o r d i n g s of M.V.,
T.V.
I n a d d i t i o n t h e d e t a i l s of t h e a n a e s t h e t i c t e c h n i q u e , t h e
gas flow r a t e s and c o n c e n t r a t i o n s , plus t h e d e t a i l s of t h e s u r g e r y and t h e d e t a i l s of t h e p a t i e n t a r e a l s o recorded.
I n e s t a b l i s h i n g t h e g u i d e l i n e s f o r f u t u r e undergraduate t e a c h i n g
I c o l l a t e d t h e d a t a from t h e l a s t 50 c a s e s recorded i n t h e waj- d e s c r i b e d . The information was processed w i t h t h e a i d o f a P.D. 1 2 l a b o r a t o r y The r a w d a t a from
computer u s i n g s t a n d a r d s t a t i s t i c a l programmes. t h e s e 50 cases i s swnmarised i n t a b l e 1.
As you can s e e , f o r t h i s
t h e mean average
c a n i n e p o p u l a t i o n w i t h a mean body weight o f 25 Kgms.
minute volume is 5.4L, t h e mean average t i d a l volume i s 269.8 mls. and t h e mean r e s p i r a t o r y r a t e i s 21.4 p e r minute. compared w i t h t h o s e of P i c k r e l l beagles which weighed between R e s p i r a t o r y Rate 24
4.
values i n dogs weighing
e t al.
25 p e r m i n .
T.V.
220
5 47, with a
Hanlin and Smith recorded t h e following
202.47 m l s R . R .
found i n dogs of body weight of 10
-
f o r 39 conscious s t a n d i n g
6 and 1 1 . 5 Kgms
7 - 33 Kgms. which had been a n a e s t h e t i s e d with
sodium p e n t o b a r t i t o n e T.V.
15
These values can b e
- 14
Kgms
13.56 p e r mn
. T.V.
125
-
and Raventos 250 rnls
R.R.
when t h e y were a n a e s t h e t i s e d with Halothane.
It i s f a i r l y obvious t h a t t h e s e parameters must be r e l a t e d t o
t h e s i z e of t h e pat i en t .
It w a s decided t o i n v e s t i g a t e t h e r e l a t i o n -
s h i p between t h e s e parameters and t h e body weight of t h e s u b j e c t . The body weight w a s s e l e c t e d as t h e most convenient measurement of body
s i z e under c l i n i c a l c o n d i t i o n s , e s p e c i a l l y as t h e m a j o r i t y of dogs a r e weighed p r i o r t o a n a e s t h e s i a .
Table 2 summarises some o f t h e
r e l a t i o n s h i p s t h a t were s t u d i e d by r e g r e s s i o n a n a l y s i s .
The r e l a t i o n -
s h i p s t h a t g i v e t h e most s i g n i f i c a n t curves a r e t h e s e where t h e l o g of o r t h e l o g of T.V. are p l o t t e d a g a i n s t t h e l o g of body weight.
M.V.
The curves of t h e s e r e l a t i o n s h i p s are i l l u s t r a t e d i n figures 1 and 2 respectively.
Three d i f f e r e n t a n a e s t h e t i c systems were used d u r i n g t h i s s t u d y ; t h e Magill on 24 o c c a s i o n s , a t o and ' f r o system on 20 o c c a s i o n s , and a c i r c l e system on
6 occasions.
I t h e n decided t o s e e i f t h e r e was any
d i f f e r e n c e between t h e systems where r e b r e a t h i n g is p e r m i t t e d and t h e There were small b u t none s i g n i f i c a n t changes i n t h e s l o p e s
Magill.
of t h e r e l a t i o n s h i p s b u t i n t h e c a s e o f t h e r e l a t i o n s h i p s between body weight and T.V. and M.V.
(P
0.01 and
P
t h e slopes a r e displaced s i g n i f i c a n t l y
0.001 r e s p e c t i v e l y )
as shown f o r M.V.
i n f i g . 3.
This o b s e r v a t i o n i s probably r e l a t e d t o a n i n c r e a s e i n dead space i n t h e r e b r e a t h i n g systems.
Another s i g n i f i c a n t o b s e r v a t i o n w a s t h e i n c r e a s e of t h e M.V. with t i m e following t h e i n d u c t i o n of a n a e s t h e s i a . cases were induced w i t h t h i o p e n t o n e sodium 2 . V .
The m a j o r i t y of
and maintained on
Halothane, n i t r o u s oxide and oxygen gas m i x t u r e s .
This i n c r e a s e
becomes h i g h l y s i g n i f i c a n t i f t h e immediately post i n d u c t i o n readings a r e compared t o t h o s e at t h e p o i n t where t h e a n a e s t h e t i c i s terminated
a t t h e completion of s u r g e r y b u t p r i o r t o t h e removal of t h e e n d o t r a c h e a l tube.
I n t h i s s e r i e s I could f i n d no s i g n i f i c a n t i n f l u e n c e o f such f a c t o r s as, age, s e x , t y p e of s u r g e r y , p o s i t i o n i n g of t h e p a t i e n t , on t h e p a t t e r n of v e n t i l a t i o n of t h e dogs s t u d i e d .
23
Conclusion Using t h e d a t a accumulated from t h e f i f t y cases s t u d i e d a guide l i n e f o r s e t t i n g gas flows i n non r e b r e a t h i n g a n a e s t h e t i c systems can b e based on t h e formulae minute volume equals 3 l i t r e s p e r minute + This formula i s based on t h e upper
140 m l s p e r kilogram p e r minute.
99% confidence l i m i t l i n e on t h e log body w e i g h t , a g a i n s t l o g min. volume curve.
Fig.
L shows t h e l i n e from t h i s s e r i e s of dogs of t i d a l
volume compared with t h o s e of M i t c h e l l f o r p i g s , h o r s e s , sheep and c a t t l e . The l i n e l a b e l l e d S t a h l i s drawn from t h e equation o f S t a h l ’ s
i n his
review of t h e s c a l i n g of v a r i o u s p h y s i o l o g i c a l parameters from shrews and whales. Anaesthesia i s known t o cause a d e c r e a s e i n r e s p i r a t o r y H a l l found a 15% d e c r e a s e i n minute volume i n l i g h t
performance.
Similar
a n a e s t h e s i a and a 60% d e c r e a s e i n deep a n a e s t h e s i a i n man.
observations i n dogs by Raventos, H a l l , Hall Morris and Markil and
It i s worth n o t i n g t h a t t h e values from t h i s s e r i e s are
Eger.
15 -
;?o$
lower when compared w i t h t h o s e of P i c k r e 1 1
f o r t i d a l volume
and r e s p i r a t o r y .
REFERENCES Dobkin, A . B . , Fedoruk, S. (1961) Anesthesiology, H a l l , L.W.
(1957)
H a l l , K.D.,
Hanlin, R.L.,
V e t . Rec.
N o r r i s , F.H. Smith, C . R .
(1958) (1967)
69:
355.
22:
615.
Anesthesiology.
19:
h e r . J. V e t . Res.
339. 28:
173.
M i t c h e l l , B. (1972) Proceedings o f t h e A s s o c i a t i o n of V e t e r i n a r y A n a e s t h e t i s t s of G.B. and I r e l a n d No. 3. 56. P i c k r e l l , J . A . e t al., (1971) Lab. Animal Science, Raventos, J. (1956) S t a h l , W.R.
(1967)
B r i t . J. Pharmacology. J . Applied Physiology.
21r
11: 394 22:
453.
21:
677.
TABLE 1
SUMMARY OF ACCUMULATED RAW DATA
Values shown i n ( ) a r e t h e s t a n d a r d d e v i a t i o n f o r t h a t p a r t i c u l a r value
Factor
Combined (A+B)
Absorber systems (A),
Magill ( B )
26 30.7 K g m . (9)
24 19.0 K g n s (8.2)
25.0 K g m s . (10.4)
6.6 l i t r e s (2.6)
4.2 l i t r e s (1.9)
5.4 l i t r e s (2.6)
218.9 m l s (83.9)
250.5
234. m l s ( 107.4)
316.3 d s (108.4)
219.0
A v . T i d a l Vol./Kgm-
11.7 m l s (4.1)
12.6 mls (4.4)
11.8 m l s (4.0)
Av. R e s p i r a t o r y Rate
21.5
21.3 (8.8)
21.4 (8.7)
No. o f cases
Av. body weight Av. Minute Volume
.
Av Min .Volume/KgmA v . T i d a l Volume
(8.7)
TABm 2
mls
( 217.9 d s
(121.5)
50
269.8 m l s (124.8)
RELATIONSHIPS EXAMINE3 Significance
Equation
2.0581 + 0.1346 body weight Min. Vol/Kgm. = 343.604 - 4.3707 body weight Min.Vo1. = 6.4376 l o g body weight - 3.2994 = 0.5951 l o g body weight - 0.121 Log.Min.Vo1. Max.Min.Vo1. = 4.6375 + 0.1465 body weight T i d a l volume = 81.6991 + 7.5071 body weight T i d a l volume/Kgm = 15.0123 - 0.1268 body weight T i d a l volume = 375.21 l o g body w g t . - 238.965 Log t i d a l volume - 1.3999 + 0.7243 l o g body weight R e s p i r a t o r y weight = 23.8902 - 0.Og98 body weight Min. Vol. =
25
p i 0.001 p < 0.01 p < 0.001
p< 0.001 p< 0.025 p< 0.001
p< 0.025 p< 0.001 p< 0.001 p< 0.1
#
0 8 #
4
10
# 0 0 0 0
8
i: F i g u r e 1.
..--
u -
The solid l i n e r e p r e s e n t s t h e r e l a t i o n s h i p d e f i n e d by t h e e q u a t i o n log Minute Volume = 0.5951 log body w g t .
-
0.121.
The d o t t e d l i n e r e p r e s e n t s t h e 99% c o n f i d e n c e limits of this line.
body wgt Figure 2 .
The s o l i d l i n e r e p r e s e n t s t h e r e l a t i o n s h i p defined by
t h e equation l o g . T i d a l Volume = 1.3993 body wgt.
+ 0.7243
m e d o t t e d l i n e s r e p r e s e n t t h e 99%
confidence limits f o r t h i s l i n e .
27
log
Figure 3.
The r e l a t i o n s h i p f o r Min. Volume and body wgt. a r e compared f o r systems designed t o be non
r e b r e a t h i n g ( n . r . ) and when
r e b r e a t h i n g i s p e r m i t t e d ( r ) due t o t h e presence of a carbon dioxide s u b s c r i b e r .
28
TIDAL VOL. 3L
2 -1
Figure
4. The s e r i e s of l i n e s s h a m a r e t h e r e l a t i o n s h i p of t i d a l volume t o body w g t . i n a number o f s p e c i e s .
The l i n e s
for h o r s e s ( h ) p i g s ( p ) c a t t l e ( c ) and sheep ( s ) are t h o s e of M i t c h e l l . t h i s project.
The l i n e f o r dog i s t h a t e s t a b l i s h e d i n The l i n e l a b e l l e d S t is t h e l i n e based on
t h e r e l a t i o n s h i p d e f i n e d by S t a h l i n h i s work on s c a l i n g o f various r e s p i r a t o r y parameters.