Brit. J. Anaesth. (1973), 45, 21
FACTORS PREDISPOSING TO POSTOPERATIVE PAIN AND PULMONARY
COMPLICATIONS
A Study of Male Patients undergoing Elective Gastric Surgery
G. D. PARBROOK, D. F. STEEL AND D. G. DALRYMPLE
SUMMARY
In 50 male patients the relationship was assessed between preoperative factors, including
personality and pain threshold, and postoperative pain and pulmonary changes. There
were highly significant correlations between neuroticism scores and postoperative changes.
Patients with a low neuroticism score were likely to have less pain, less impairment of
pulmonary vital capacity and a lower incidence of postoperative complications. Analysis
of extraversion scores was less conclusive. A high psychoticism score was associated
with a high neuroticism score, but psychoticism did not otherwise affect the results.
There was no significant correlation between preoperative pain threshold and postoperative faaors. The analyses of the effea of the non-psychological preoperative factors
on postoperative pain severity and pulmonary complications showed less significant
results than those with neuroticism. Pulmonary complications were higher in those
patients with pre-existing chest disease and the incidence of postoperative pain appeared
lower in those patients who had received intraoperative analgesia. Close correlation was
found between the postoperative subjective assessment of pain and vital capacity impairment. The patient's neuroticism score warrants greater attention in studies of postoperative pain.
This trial was designed to find out whether correlations could be deteaed between patient faaors, which
were assessed preoperatively, and the subjective pain,
vital capacity changes and pulmonary complications
found after operation. If a strong relationship could
be found between certain preoperative faaors and
postoperative results, then it would be justifiable to
advocate those preoperative tests routinely to indicate
patients who are most likely to have severe postoperative pain and pulmonary complications.
During previous studies of the pain relief obtained
with nitrous oxide one of the authors found a wide
range of severity of pain, some patients having severe
and some no pain after identical operations (Parbrook and Kennedy, 1964; Parbrook, Rees and
Robertson, 1964; Parbrook, 1966). Patients experiencing greater pain are likely to show a greater
reluctance to move and cough effectively and, consequently, they will have a high incidence of postoperative complications. In view of this, better identification of patients who are likely to have severe
postoperative pain should not only allow closer identification of those needing special analgesic techniques, but may also give advance indication of the
patients who will have greater risks of pulmonary
complications. Of the preoperative faaors likely to
affect the patient's pain experience, the patient's personality and pain threshold appeared to warrant particular attention in this trial.
Patients having upper abdominal operations are
especially likely to have severe pain (King, 1933;
Parkhouse, Lambrechts and Simpson, 1961; Masson,
1967) and, consequently, these patients were chosen
as being particularly appropriate for these studies.
Apart from the limitation in the selection of patients,
alterations of the normal ward and clinical routines
were carefully avoided in order to render this trial as
applicable as possible to the normal patient care as
it applies in our hospital.
METHODS
The study was restricted to male patients between 20
and 60 years of age who had been admitted to hospital for elective peptic ulcer surgery.
Preoperative Assessment
The patients were seen on the day before surgery,
the nature of the study was explained to them and
G. D. PARBROOK. MJX, F.F.A.R.CS.; D. F. STEEL, M.R,
CH.B., F.F.A.R.C.S.; D. G. DALRYMPLE, M.B., CH.B.; Univer-
sity of Glasgow, Department of Anaesthesia, Royal Infirmary, Glasgow G4 OSF.
22
their consent to take part in it obtained. General
patient details, namely, age, marital status, religion,
occupation, smoking habits, current drug therapy and
the absence or presence of pre-existing chest or cardiac disease, were all noted. At the same time the
following special assessments were made-
BRITISH JOURNAL OF ANAESTHESIA
corded with special reference to the drugs used for
premedication, the use of suxamethonium and the
use of analgesic drugs during the operation. The
presence or absence of nasogastric tubes and/or
abdominal drains was also recorded.
Postoperative Assessments
Early assessment.
The first postoperative assessment was made at 24
hours after surgery, or as near to 24 hours as possible, to avoid times within 4 hours of narcotic medication and/or visits by physiotherapists. To assess the
patient's pain the graphic method was used (Clarke
and Spear, 1964; Bond and Pilowsky, 1966). This
consists of a 10 cm line, at the left-hand end of which
it states "I have no pain" and at the right-hand end
"My pain is as bad as it can be". The patient is
asked to mark with a pencil on the line where he
feels his pain lies, and the distance from the left hand
to the point of interception of the mark gives the
subjective pain score in cm. The use of an analogue
scale, such as in this technique, facilitates statistical
analysis and partly circumvents the problem that
adjectives used for different degrees of pain may not
Vital capacity measurement.
indicate the same quantities to different people. The
A Morgan Mark II spirometer was used. The
general practice involved in the use of visual analogue
patients were shown how to use the spirometer and
scales has been described in detail by Aitken (1969).
were allowed preliminary practice in vital capacity
After the patient had recorded his pain score the
measurement. The mean of three readings was then
pain
threshold readings were repeated and, finally,
taken as the preoperative baseline for comparison
after a 15-min rest period, the patient's vital capacity
with postoperative vital capacity changes.
measurement was recorded, using the Morgan Mark
II spirometer, with which the patient was already
Assessment of patient's pain threshold.
The pain threshold was measured by tibial pain conversant. For both pain threshold and vital capacity
technique, using a pressure algesimeter (Clutton- recordings the mean of three readings was taken and,
Brock, 1957). The pressure was increased on the in the case of vital capacity, impairment was exalgesimeter at the rate of approximately 1 kg/sec pressed as a percentage of the preoperative value. In
and only the lower pain threshold was used, i.e. the addition to providing an index of postoperative reslevel at which the patient first becomes aware of pain. piratory dysfunction, the vital capacity impairment
The upper pain threshold, the so-called 'Very severe" should give a second indication of the degree of pain
pain threshold, was not used as it was felt essential to experienced by the patient (Overholt, 1930; Bromage,
avoid distressing the patients and losing their confi- 1955; Masson, 1962; Parbrook and Kennedy, 1964)
dence. As in the case of vital capacity readings, the and the relative importance of pain in impairing vital
capacity is indicated by the restoration of vital
mean of three readings was taken.
Preoperatively the patients were also given pre- capacity to normal by epidural analgesia (Bromage,
liminary instruction into the graphic technique of 1955; Simpson et al., 1961). Consequently, the vital
pain measurement, which was to be used postopera- capacity impairment could be used as a measure of
tively. Further details of this are given below under dynamic pain, or pain on movement, to supplement
the resting pain measurements assessed by the graphic
"Postoperative Assessments".
method.
Operation
Finally, the number, dose and type of narcotic inThe time, the duration and the details of the opera- jections received by the patients in the first 24 hours
tion were noted. The anaesthetic details were re- after surgery was also recorded. These injections were
Assessment of personality.
The patient's personality can be assessed by means
of a questionnaire and the one used in this trial was
the PEN Inventory. This is the most recent of the
series of personality questionnaires developed by
Eysenck (Eysenck and Eysenck, 1968). It consists of
78 questions designed to measure three dimensions of
personality, namely, psychoticism (P), extraversion
(E) and neuroticism (N). Psychoticism assesses the
tendency to psychotic traits in the patients. The
dimension of intraversion/extraversion reflects
people's sociability. Those with low E scores are intraverted, or more reserved, whereas those with high
scores tend to be more outgoing in nature. The
neuroticism factor measures emotional stability and
proneness to anxiety.
23
FACTORS PREDISPOSING TO POSTOPERATIVE PAIN
prescribed by the surgical staff without any interference from the clinical investigators.
Late postoperative assessment.
The patient's progress was noted during the days
after operation and a postoperative vital capacity
measurement was taken again on the 6th postoperative day. Chest complications which occurred during
the 6 postoperative days were assessed using the
following criteria, each scoring one point: (i) Pyrexia
over 37.5°C, persisting for 48 hours or more, (ii) New
or increased cough, (iii) New or increased sputum
production, (iv) Positive bacteriological culture of the
sputum, (v) Antibiotic therapy prescribed for chest
complications by the surgical staff, who were unaware
of the scoring assessment
Neuroticism score and postoperative factors.
There were strong positive correlations between
the neuroticism score and the postoperative changes,
namely, resting pain (measured by the graphic scale),
vital capacity impairment at 24 hours, vital capacity
impairment on the 6th postoperative day and the
number of injections required by the patients in the
first 24 hours after surgery. The type of narcotic used
varied, but the dose per injection was equivalent to
between 10 and 13 mg of morphine sulphate. There
was also a highly significant positive correlation
between neuroticism and the chest complication score
both for the group as a whole and for the 38 patients
without pre-existing chest disease. The results are
best illustrated by the scattergrams (figs. 1-5), the
correlation analyses being given in table II.
RESULTS
Of the 50 patients participating in this study 47
underwent vagotomy and drainage procedures, 1 had
a partial gastrectomy and 2 had laparotomies. All
patients had upper abdominal incisions, 41 mid-line
epigastric and 9 left paramedians.
All patients received opiate premedication and the
range of duration of the operation was from 30 to 150
min, with a mean duration of 63 min
Where possible the results are presented in the
form of correlation analyses. Results of the personality
analyses are given in greater detail as these appeared
to be of overriding importance. Full details of the
group as a whole are given in table I.
TABLE I.
Group mean results for pre- and
factors measured.
Age (yr)
Personality factors
Neuroticism (N)
Extroversion (E)
Psychoticism (P)
Lie
(L)
Pain threshold (kg/0.64 cm1)
Preoperative
Postoperative
Vital capacity (1.)
Preoperative
Postoperative—24 hr
Postoperative—6 days
Vital capacity impairment
(% of preoperative value)
Postoperative—24 hr
Postoperative—6 days
Pain score at 24 hr (cm)
No. of analgesic injections
in first postoperative 24 hr
Chest complication score
postoperative
Mean
SD
Range
41.4
11.0
21-60
9.0
12.4
2.2
3.5
4.3
5.1
2.2
2.6
0-16
3-19
0-9
0-13
3.9
3.5
1.2
1.1
2.2-8.0
1.4-6.0
3.6
1.0
2.5
0.7
0.4
0.8
2.4-4.8
0.2-2.0
71.6
29.6
4.2
10.0
18.3
3.1
45-93
2.0
1.8
1.0
(M
1.5
0-4
0-80
0-10
10
9
8
7
6
5
4
C
1
I
3
2
8
10
12
14
16
N Score
FIG. 1. The scattergram illustrates the highly significant
correlation between the neuroticism score (N) and the
resting pain score 24 hours after operation.
Extroversion/introversion scores.
Before considering the correlation between extraversion and postoperative factors, one must first take
into account the interrelationship between extroversion and neuroticism. This is illustrated in the scattergram (fig. 6). In our series of peptic ulcer patients we
found that stable patients with an N score under 8
were nearly always extraverted. In this series only one
stable intravert was observed.
24
BRITISH JOURNAL OF ANAESTHESIA
100
4
I
90
•
•
I
80
70
i:
• •
•
60
8
10
12
14
16
N Score
FIG. 4. The scattergram shows a trend for chest complication scores to be higher in the patients with the higher
neuroticism scores.
50
•
0
2
4
6
8
10
12
14
16
N Score
FIG. 2. The scattergram shows the increased vital capacity
impairment in patients with higher neuroticism (N) scores.
ore
40
•
3
•
•
•
•
2
• •
•
• • •
&
|
•
•
• • •
o
"5.
80
J
70
1
•
•
• •
•
• •
10
12
to
60
il
O
•
50
.
"
•
•
i
40
30
• •
•
:
•
•
•
B
-•
0
0
2
4
•
. •
•
•
•
8
10
14
16
N Score
•
•
• •
10
8
FIG. 5. The patients with a higher neuroticism score
received a greater number of analgesic injections in the
first 24 hours after surgery.
•
20 •
0
.
12
14
16
N Score
FIG. 3. The increased vital capacity impairment in
patients with higher neuroticism (N) scores is still present
6 days after operation.
When the extraversion scores were correlated with
the subjective pain scores at 24 hours, the vital
capacity impairments at 24 hours, the number of
analgesic injections received, and the chest complication scores, the only significant correlation was the
one between extraversion scores and chest complication scores. To try to eliminate the effects of neuroticism on these correlations the four results were reanalysed for patients with a neuroticism score over 8.
FACTORS PREDISPOSING TO POSTOPERATIVE PAIN
20
D=N<8
18
]
16
• =N>8
• a
•
•
• • •
•
• •
•
• •
•
D
o
Q
D
14
12
D
a
S
a
10
a
•
•
•
8
6
5 • • • •
•
•
•
•
•
•
4
•
2
0
8
10
12
14
16
N Score
FIG. 6. The scattergram shows the distribution of extraversion (E) and neuroticism (N) in the patients in the
trial. There was a lack of stable intraverts in this group of
patients and there was a highly significant correlation of
N with E (correlation coefficient = 0.457, deviation of slope
from zero 1 = 3.559, P-CO.001).
The only significant correlation then found was the
one between extroversion scores and the number of
analgesic injections. The previous positive correlation
between extraversion and chest complications became
insignificant. The results are given in table III.
Psychoticism.
In the case of psychoticism, the third aspect of personality measured, there was a marked asymmetry of
the scores, making the results unsuitable for correlation analysis. The majority of patients had a psychoticism score of 3 or under 3 and these were
analysed as a separate group from those with a high
psychoticism score of over 3.
A problem of analysis of psychoticism results is
that the patients with high psychoticism scores have
high neuroticism scores (over 8 in our trial). Although
there appeared to be higher means for pain scores,
vital capacity impairment and number of analgesic
injections in the "psychotic" group of patients, these
trends disappeared when one compared this group
with the "non-psychotic" group who had high neuroticism scores (table IV).
25
Lie score.
In addition to the three aspects of personality discussed above the PEN Inventory also includes a "lie
score" which gives a measure of the patient's tendency to exaggerate. There were no positive correlations between the lie score and postoperative factors.
Pre- and postoperative pain thresholds.
There were no significant correlations between the
preoperative pain threshold and postoperative factors.
Pain thresholds were lower postoperatively (table I),
but the difference between preoperative and postoperative readings did not reach full statistical significance (P<0.1). Postoperative pain thresholds
showed a significant correlation with vital capacity
impairment (table V).
Other preoperative factors.
The effect of other preoperative factors was
assessed, but in no case did results achieve the marked
significance shown with neuroticism. Results are given
briefly as follows:
Age. There may be a slight trend for younger
patients to have a greater vital capacity impairment
at 24 hours and on the 6th postoperative day. The
results are given in greater detail in table VI.
Social class. There were no patients in social classes
1 or 2 in this trial. Twenty-five patients were in social
class 3, 16 in class 4, and 9 in class 5. The subjective pain score, vital capacity impairment and chest
complication scores were all higher in the lower social
classes (4 and 5) (table VII). However, these social
classes also had a higher neuroticism score and analysis of groups according to an N score over 8 suggests
that it was the neuroticism score rather than social
class which was playing the more important part
(table VIII).
Pre-existing chest disease. Twelve patients of this
series were judged to have pre-existing chest disease
and there was a higher chest complication score in
this group (table IX).
Cigarettes. Only 6 of the 50 patients were nonsmokers and in view of the small numbers these are
included in table X with patients who smoked less
than 10 cigarettes per day and compared with those
who smoked 10-20 cigarettes and those who smoked
over 20 per day.
There was a high incidence of pre-existing chest
complications in heavy smokers, but those smoking
over 20 cigarettes a day had a lower neuroticism score
and suffered significantly less pain.
Suxamethonium. Although the overall results
26
BRITISH JOURNAL OF ANAESTHESIA
TABLE II. Correlation analysis for neuroticism and postoperative changes.
Correlation
coefficient
N v. Pain score (graphic method)
Slope
0.5850
(P<0.001)
0.4500
(P<0.01)
0.3618
(P<0.05)
0.3300
(P<0.05)
0.5080
(P<0.001)
0.5174
(P<0.001)
N v. V.C. impairment at 24 hr
N v. V.C. impairment on 6th
postoperative day
N v. No. of narcotic injections
in first 24 hr
N v. Chest complication score
(deviation of
Estimate slope from
of error
zero)
N v. Chest complication score in
patients with no pre-existing chest disease
N = Neuroticism score
0.425
2.57
4.993
1.039
8.980
3.491
1.475
16.380
2.604
0.758
0.944
2.423
0.180
1.330
4.086
0.160
1.222
3.628
TABLE III. Correlation analysis for extroversion and postoperative changes.
Correlation
coefficient
All patients
Slope
(deviation of
Estimate slope from
of error
zero)
E v. Pain score
0.0930
-0.076
3.15
0.646
E v. V.C. impairment at 24 hr
0.1236
-0.324
9.97
0.8627
0.000
0.000
0.00
0.000
0.3600
(P<0.05)
-0.145
1.44
2.669
E v. Pain score
0.271
0.217
2.87
1.513
E v. V.C. impairment at 24 hr
0.194
0.444
8.35
1.062
0.382
(P<0.05)
0.128
0.106
0.95
2.228
-0.048
1.40
0.693
E v. No. of injections in first 24 hr
E v. Chest complication scores
Patients with N score>8
E v. No. of injections in first 24 hr
E v. Chest complication scores
E = Extroversion score
TABLE IV.
The effect of psychotidsm on postoperative pain and vital capacity impairment.
Psychoticism
(P) score
Over 3*
(all patients)
3 and under 3
(all patients)
3 and under 3
(with N score over 8)
No. of
patients
Neuroticism
(N) score
12
12.67
(2.23)
7.79
(4.15)
11.37
(1.80)
38
19
Pain score
at 24 hr
5.25
(2.90)
3.87
(3.16)
6.11
(2.98)
V.C
impairment
at 24 hr
73.50
(9.00)
70.97
(10.27)
76.26
(8.01)
Standard deviations are given in brackets.
*A11 the patients with a psychoticism score of over 3 had an N score of over 8.
No. of
analgesic
injections
2.42
(1.00)
1.86
(0.96)
2.26
(1.05)
27
FACTORS PREDISPOSING TO POSTOPERATIVE PAIN
TABLE V. Correlation analysis for pre- and postoperative
pain thresholds.
Correlation
coefficient
t (deviation
of slope
from zero)
0.205
1.451
Preoperative pain threshold
v. Pain score (24 hr)
v. V.C impairment (24 hr)
0.243
(P<0.1>0.05)
v. V.C. impairment (6 days) 0.0439
0.2948
v. No. of injections
0.1941
1.3706
v. Chest complication
0.1513
Neuroticism v. Preoperative
pain threshold
0.1883
Extroversion v. Preoperative
pain threshold
0.1047
Postoperative pain threshold
v. Pain score (24 hr)
0.2588
(P<0.1>0.05)
v. V.C impairment (24 hr)
0.2990
(P<0.05)
1.7350
1.0606
1.3281
0.7297
1.8566
2.1712
showed a higher pain score in the 25 patients who
received suxamethonium, as compared with the 25
who did not, the suxamethonium patients by chance
had also a higher neuroticism score. By breaking down
the series into four, according to a neuroticism score
above or below 8, one sees that the apparent effects
of suxamethonium could well have been secondary to
an uneven distribution of neuroticism in the two
groups (table XI).
Analgesic supplementation of anaesthesia. Ten
patients out of the 50 had analgesic supplementation
during anaesthesia, in the form of intravenous narcotics. There was a higher subjective pain score at 24
hours in the group that did not have analgesic supplementation (table XH).
Other variables. Other variables are analysed as
shown in table XII. No significant differences were
found for patients with different religioa There was
no difference in the instance of postoperative pain in
patients from two different surgical units, and the
presence of nasogastric rubes or abdominal drains did
not affect the pain scores in this series. The form of
TABLE VI. Correlation analysis for age.
(deviation of
slope from zero)
Correlation
coefficient
Slope
Age u. N
0.1944
-0.076
1.370
Age v. Pain score
0.2190
-0.062
1.556
-0.226
1.795
-0.400
1.976
-0.004
0.272
-0.006
0.289
Age v. V.C. impairment (24 hr)
Age v. V.C. impairment (6 days)
Age v. No. of analgesic injections
Age v. Chest complication score
TABLE VII.
Social class
Class 3
Class 4
Class 5
No. of
patients
25
16
9
Statistical
analysis
3 v. 4 r=
3 v. 5
i=
4 v. 5
r=
0.2588
(P<0.1>0.05)
0.2743
(P<0.1>0.05)
0.0392
0.0416
The effect of social class on postoperative pain experience.
Chest
complication
No. of
score
injections
Pain score
V.C
impairment
(24 hr)
13.8 (3.8)
11.5 (2.6)
10.1 (4.4)
3.0 (3.0)
5.4 (2.9)
5.3 (2.9)
68.2 (9.4)
76.7 (6.3)
71.8 (13.4)
1.8 (1.0)
2.3 (0.9)
2.2 (1.1)
1.0 (1.3)
2.5 (1.4)
2.2 (1.1)
2.3037
(P<0.05)
2.2396
(P<0.05)
0.8646
2.4635
(P<0.02)
2.0255
(P<0.10)
0.0414
3.4420
(P<0.01)
0.7315
(P>0.1)
0.0381
1.6177
(P>0.1)
1.1146
(P>0.1)
0.0694
3.4559
(P<0.01)
2.7552
(P<0.01)
0.5515
N score
E score
7.0 (4.0)
10.9 (3.7)
11.1 (4.0)
3.2363
(P<0.01)
2.6649
(P<0.02)
0.1420
28
BRITISH JOURNAL OF ANAESTHESIA
the trial, however, was not such as to reveal small
differences which could well have been present, but
was rather to indicate major trends.
•
90
.
•
Interrelationship
80
between postoperative
factors.
There was a highly significant correlation between
pain when assessed by the graphic method and vital
" capacity expressed as a percentage of the preoperative
value (fig. 7). Similarly there were strong correlations
between other postoperative factors and some trends
as indicated in table X K .
"
12
70
DISCUSSION
60
Normal clinical routines were not altered in this trial,
|
as it was hoped by this method to render the results
more relevant to normal clinical circumstances, and,
in addition, to identify more readily the more im50
portant factors influencing postoperative pain and
progress. Results show that one factor, the neuroticism dimension of personality, was of overriding
40
9""™To importance and no other preoperative factor showed
such a strong correlation with the postoperative proResting Pain Score
gress.
The correlations between neuroticism, postoperaFIG. 7. The figure shows the strong positive correlation
I
between pain assessment as measured by the, resting pain
score and the percentage vital capacity impairment. Both
measurements were made 24 hours after surgery.
p ^ yjtal capacity impairment and complica.
^T^
-i • j , «•
aons, do not necessarily indicate a cause/effect re-
tive
TABLE VIII. Analysis of social class and neuroticism.
Social
class
Neuroticism
No. of
patients
in group
Pain
score
Over 8
3
4 and 5
10
21
5.1 (3.8)
6.1 (2.5)
Under 8
3
4 and 5
15
4
1.7 (1.1)
1.5 (1.0)
V.C
impairment
(24 hr)
7Z8
76.3
65.2
67.5
(9.6)
(7.7)
(8.2)
(15.5)
Chest
complication
score
1.5
2.9
0.7
1.3
(1.5) \ . = 2.5416
(1.1) / P<0.02
(1.0)
(1.9)
Standard deviations are given in brackets.
TABLE IX. Analysis for the effect of pre-existing chest disease.
Group
No pre-existing
chest disease
Pre-existing
chest disease
Statistical
analysis
t=
P=
No. of
patients N score
E score
Chest
complication
score
Cigarettes
(per day)
Pain
score
38
8.7 (4.5)
13.0 (3.5)
1.5 (1.5)
17.5 (11.7)
4.5 (3.2)
12
9.7 (3.6)
10.5 (4.1)
2.8 (1.3)
22.5 (6.9)
3.2 (2.8)
0.787
>0.1
Standard deviations are given in brackets.
1.893
<0.1
3.009
<0.01
1.834
<0.1
1.353
>0.1
29
FACTORS PREDISPOSING TO POSTOPERATIVE PAIN
TABLE X. Relationship between cigarette smoking and postoperative factors.
Group
A None and light
0-10 cigs a day
B Moderate
11-20 cigs a day
C Heavy
Over 20 cigs a day
Statistical analysis
B v. C t
P
A v.C
t
P
Pre-existing
Chest
chest
complication
disease
score
No. of
patients
N score
E score
Pain score
V.C
impairment
at 24 hr
11
8.6 (4.4)
13.0 (4.4)
5.2 (3.8)
73% (11)
1 (9%)
1.5 (1.4)
25
10.2 (4.1)
11.8 (3.4)
4.9 (2.7)
74%
(9)
5 (20%)
2.0 (1.5)
14
7.0 (4.2)
12.9 (4.2)
2.2 (2.6)
67%
(9)
6 (43%)
1.6 (1.8)
2.319
<0.05
n.s.
n.s.
n.s.
Standard deviations are given in brackets.
3.066
2.2414
<0.01
<0.05
2.244
<0.05
n.s.
as.=Not significant, P>0.1.
n.s.
n.s.
TABLE XI. Influence of suxamethonium on postoperative pain and analysis according to
neuroticism score.
V.C.
No. of
impairment
No. of
Group
patients
N score
Pain score
(24 hr)
injections
74.3 (9.3)
2.2 (0.9)
Suxamethonium
10.0 (3.8)
5.1 (3.1)
25
3.3 (3.0)
68.8 (10.0)
1.8 (1.0)
No suxamethonium
25
7.9 (4.6)
Statistical analysis
t
1.742
2.155
2.007
1.444
P
<0.05
<0.1
>0.1
Suxamethonium
f 6.1 (2.9)
76.6 (7.8)
19 \
No suxamethonium
12 /
over 8
\ 5.25 (3.1)
73.0 (9.1)
Suxamethonium
6 \
/ 2.0 (0.9)
67.2 (10.9)
No suxamethonium
13 / under 8
1 1.5 (1.1)
65.0 (9.4)
Standard deviations are given in brackets.
TABLE XII.
Analysis for analgesic supplementation of anaesthesia and othervariables.
No. of
patients
V.C.
impairment
(24 hr)
No. of
analgesic
injections
N score
Pain score
Analgesic supplementation
of anaesthesia
10
Supplemented
8.3 (5.3)
2.7 (2.5)*
69.1 (6.3)
1.6 (1.0)
40
Not supplemented
9.1 (4.1)
4.6 (3.2)*
72.2 (10.6)
2.1 (1.0)
Abdominal drains
12
Drain
10.7 (4.9)
5.2 (3.5)
75.5 (13.2)
2.3 (1.0)
38
No drain
8.4 (4.0)
3.9 (3.0)
70.3 (8.5)
1.9 (1.0)
Nasogastric tube
9.5 (4.1)
23
Nasogastric rube
4.6 (3.2)
72.4 (10.7)
1.7 (1.0)
8.5 (4.5)
27
No nasogastric tube
3.9 (3.1)
70.9 (9.4)
2.2 (0.9)
Environment
20
Unit A
9.8 (4.5)
3.9 (2.9)
71.6 (9.5)
1.9 (0.9)
30
Unit B
8.4 (4.2)
4.4 (3.3)
71.6 (10.4)
2.1 (1.1)
Religion
17
9.4 (4.2)
5.0 (2.8)
2.1 (1.1)
72.7 (6.0)
Catholic
33
Protestant
8.7 (4.4)
3.8 (3.2)
71.0 (11.5)
2.0 (0.9)
Surgical Incision
9
Paramedian
10.1 (2.9)
4.4 (3.1)
74.0 (11.2)
2.3 (0.9)
41
Mid line
8.7 (4.6)
4.2 (3.2)
71.1 (9.7)
1.9 (1.0)
Standard deviations are given in brackets.
*The lower 24 hour pain score after anaesthesia supplemented with analgesia was significant
(=2.019, P<0.05.
'
^ ^
30
BRITISH JOURNAL OF ANAESTHESIA
TABLE XIII.
Correlations between other postoperative factors.
Correlation
coefficient
Pain score
v. V.C impairment (24 hr)
v. No. of analgesic injections
V.C. impairment (6 days) v. Chest
complication score
Pain score
v. V.C impairment (6 days)
V.C. impairment (24 hr) v. Chest
complication score
0.7389
(P<0.001)
0.5139
(P<0.001)
0.6408
(P<0.001)
0.2687
(P<0.01)
0.2661
(P<0.01)
Slope
2.348
0.166
0.055
1.461
0.041
( (for deviation
of regression
slope from zero)
7.598
(P<0 001)
4.1501
(P<0 00l)
5.5987
(P<0 001)
1.8715
(P<0.1)
1.9123
(P<0.1)
lationship, but we were unable to identify any other periencing severe pain. The results also suggest that
factors which could have led to these results. It seems in future pain studies or studies of postoperative comreasonable to postulate that the patient's neuroticism plications it is now desirable to check the neuroticism
makes him more susceptible to postoperative pain and scores of the groups being compared. Other workers
pulmonary complications. In support of this, the N have shown that psychological testing may, in addiscore indicates proneness to anxiety and there is little tion, aid in preoperative prediction of the success or
doubt that anxious patients are likely to have more failure of gastric surgery (McColl et al., 1971).
severe pain. The interrelationship between neuroIn contrast to the results with the neuroticism score
ticism and pain that we found is in agreement with the correlation analyses for extraversion showed a less
the work of Bond and Pearson (1969). In their study clear relationship. In our series we found that stable
of a group of female patients with cancer, these wor- patients, with an N score of under 8, are nearly always
kers found significantly lower N scores in those who extraverted. This would appear to be due to the
did not complain of pain. Lovell and Verghese (1967) nature of the peptic ulcer patients in the trial. As
also found that patients who complained of left chest these patients with an N score under 8 are those who
pain and angina after myocardial infarction had the had a lower instance of postoperative pain one might
highest scores for neuroticism. On a more general expect extraverted patients in general to suffer less
basis most will agree that there is a relationship pain. The results did not show such a relationship,
between psychological make-up and severity of post- there being many extraverted patients with severe
operative pain (Leading Article, 1964; Masson, pain, and there was no significant correlation either
1967). Parkhouse, Lambrechts and Simpson (1961) between extroversion and pain for the group as a
considered that the wide variation in the need for whole or for the extraverted patients who had an N
narcotics after surgery was related to differences in score of over 8. The only significant correlation for
the patient's mental characteristics. It is also known the group as a whole for extraversion was between
that the personality of a patient may influence his this factor and postoperative complications. The reattitude to pain (Petrie, 1960), and that pain and the lationship was less marked than the relationship for
reaction to it can be markedly altered by psychological neuroticism and analysis for the patients with an N
stress and different emotional states (Mahno, 1954; score over 8 suggested that this effect could have been
Beecher, 1956, 1959). Previous investigations into accounted for entirely by the asymmetry of neurotithis aspect of postoperative pain, however, have dealt cism distribution in the patients. The analysis of the
mainly with reduction of analgesic medication, which number of injections against extraversion for the
can be achieved by preoperative instruction and en- patients with a high neuroticism score showed that in
couragement (Roe, 1963; Egbert et al., 1964; Ulert, this gToup extraverted patients received more post1967; Finer, 1970).
operative analgesia and this finding is in agreement
with
the work of Bond and Pearson (1969), who
Our own studies suggest that it may be possible to
identify on a group basis those patients who are more found that extraverted patients received more anallikely to have more severe pain and complications, gesia. Complaining and requests, therefore, for analand psychological testing may even be of assistance gesics may be more likely to occur in extraverts, if,
in indicating the chances of an individual patient ex- as has been suggested, the E personality factor is
31
FACTORS PREDISPOSING TO POSTOPERATIVE PAIN
related to the degree of excitation present in the
nervous system, which in turn, according to Bond
and Pearson (1969), determines their complaint
behaviour.
Analysis of preoperative pain thresholds failed to
show a significant correlation with postoperative pain
severity and complications. This result is disappointing in view of the studies of Keele (1968) on patients
with myocardial infarction. Keele found that patients
whose pain thresholds were elevated were less likely
to have severe pain and heavy analgesic requirements.
Nevertheless, postoperative pain threshold measurements in our study did show a trend for vital capacity
impairment to be less in patients with higher postoperative pain thresholds and the study cannot exdude the possibility of a small effect from pain threshold on postoperative pain appreciation. A fall in
pain threshold postoperatively is in general agreement
with the findings of other workers, who found that, in
the presence of pain, the pain threshold is depressed
(Bond and Pearson, 1969).
Results from analysis of other factors suggested
that these too were of less importance than neurotidsm as an indication of the patient's postoperative
pain and complications. A relationship between age
and postoperative pain and complications was expected as other workers have suggested that older
patients require less analgesia in the postoperative
period (Pratt and Welch, 1955; Parkhouse, Lambrechts and Simpson, 1961). In addition neuroticism
is shown to be higher in the younger age groups
(Eysenck and Eysenck, 1969). The results in our
study did not exclude the possibility of trends of this
sort.
As did other workers (Eysenck and Eysenck, 1969),
we found that neuroticism scores were higher in the
lower social class patients and the higher pain experience of these patients was probably secondary to
the personality factors. An additional factor contributing to the higher incidence of postoperative chest
complications in patients in social classes 4 and 5 was
the high incidence of pre-existing chest disease. In
agreement with other workers (Palmer and Sellick,
1953; Wightman, 1968) the incidence of postoperative pulmonary complications was higher in patients
with pre-existing chest disease. The adverse effects of
smoking were less clearly demonstrated in this trial.
There was a suggestion of a trend for the heavy
smokers to have a lower neuroticism score and in this
context it is of interest to note that Kissen and
Eysenck (1962), in a study of male patients with lung
cancer, found low neuroticism scores in these patients.
It is possible, therefore, that the personality of the
patient may lead him into his heavy smoking habits.
The lower neuroticism score in the heavier smokers
would also provide a possible explanation of the lower
resting pain scores in these patients.
Generalized muscle pains occur after the use of
suxamethonium and there is some evidence that these
pains may limit vital capacity even after minor operations (White, D. C.j personal communication). Although our overall results demonstrated a higher pain
score in those patients who received suxamethonium,
these patients also had a high neuroticism score and
closer analysis suggested that it was this latter factor,
rather than suxamethonium, that had led to this
result. It has been claimed that analgesic supplementation during operations reduces postoperative pain
(Martin et al., 1967; Dundee et al., 1969) and the
current study confirmed this trend in spite of the
fact that the effect from such supplementation of
anaesthesia might only be expected to be operative in
the immediate postoperative phase. Although no
significant differences were found in many of the
intraoperative and preoperative factors when correlated with postoperative progress, the design of the
trial was not such as to reveal small differences, but
was intended rather to identify the major factors.
An interesting finding in the current study was the
strong correlation between subjective measurements
of pain and the objective measurement in terms of
vital capacity impairment. This result was in keeping
with the findings of a previous trial (Parbrook and
Kennedy, 1964), in which quite minor differences of
analgesia could be detected in a small group of
patients on a double blind basis, using vital capacity
impairment. Our results, in showing a correlation
between subjective and objective pain measurement,
may appear to conflict with the observations of Loan
and Dundee (1967). The latter workers found no such
relationship, but their studies were timed at a different period, earlier after surgery, and measurements
were made 60 min after opiate had been administered.
CONCLUSION
Findings of this study indicate that personality factors, and particularly neuroticism, play an important
role in postoperative pain and pulmonary complications. Personality assessment by an inventory, such as
the PEN Inventory, may aid in detecting those
patients who are likely to need special attention in
the postoperative period. It would appear to be important to take the patient's neuroticism into account
in future studies into postoperative pain and complications.
BRITISH JOURNAL OF ANAESTHESIA
32
ACKNOWLEDGEMENTS
Professor H. J. Eysenck is thanked for provision of the
PEN Inventories and advice on the psychological aspects of
this trial was provided by Dr G. S. Qaridge and Dr M. R.
Bond. Professor A. C. Forrester and members of the
Department of Anaesthetics at Glasgow Royal Infirmary
provided encouragement in this study and the surgeons of
the Royal Infirmary are thanked for their co-operation.
Statistical advice was provided by Mr D. A. McLaren of
the Department of Statistics, University of Glasgow, and
this research was supported by a grant from the Medical
Research Council.
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Qutton-Brock, J. (1957). The cerebral effects of overventilation. Brit. J. Anaesth., 29, 111.
Dundee, J. W., Brown, S. S., Hamilton, R. C , and
McDowell, S. A. (1969). Analgesic supplementation of
light general anaesthesia: a study of its advantages using
. sequential analysis. Anaesthesia, 24, 52.
Egbert, L. D., Battit, G. E., Welch, C E., and Bartlttt,
M. K. (1964). Reduction of postoperative pain by
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Eysenck, H. J., and Eysenck, S. G. B. (1968). The measurement- of psychoticism: a study of factor stability and
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Eysenck, S. G. B., and Eysenck, H. J. (1969). Scores on
three personality variables as a function of age, sex and
social class. Brit. J. soc. clin. Psychol., 8, 69.
Finer, B. (1970). Studies of the variability in expiratory
efforts before and after cholccystectomy. Acta anaesth.
scand., Suppl. 38.
Keele, K. D. (1968). Pain complaint threshold in relation
to pain of cardiac infarction. Brit. med. J., 1, 670.
King, D. S. (1933). Postoperative pulmonary complications.
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Kissen, D . M., and Eysenck, H. J. (1962). Personality in
male lung cancer patients. J. psychosom. Res., 6, 123.
Leading Article (1964). Postoperative pain. Lancet, 1, 751.
Loan, W. B., and Dundee, J. E. (1967). The value of the
study of postoperative pain in the assessment of analgesics. Brit. J. Anaesth., 39, 743.
Lovell, R. R. H., and Verghese, A. (1967). Personality
traits associated with different chest pain after myocardial infarction. Brit. med. J., 3, 327.
McCoU, I., Drinkwater, J. E., Hulme-Moir, I., and
Donnan, S. P. B. (1971). Prediction of success or failure
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Martin, S. J., Murphy, J. D., Colliton, R. J., and Zeffiro,
R. G. (1967). (Tinirni studies with Innovar. Anesthesiology, 28, 458.
Masson, A. H. B. (1962). Clinical assessment of analgesic
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(1967). The role of analgesic drugs in the treatment
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Palmer, K. N. V., and Sellick, B. A. (1953). The prevention
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Parbrook, G. D. (1966). Postoperative pain relief: comparison of methadone and morphine when used concurrently
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Kennedy, B. R. (1964). Value of premised nitrous
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FACTEURS PREDISPOSANTS A LA DOULEUR
POSTOPERATOIRE ET AUX COMPLICATIONS
PULMONAIRES: UNE ETUDE DE PATIENTS
MASCULINS SUBISSANT DE LA CHIRURGIE
GASTRIQUE ELECTIVE
SOMMAIRE
Le rapport entre les facteurs preoperatoires, y inclus la
personality et de seuil de douleur, et la douleur postoperatoire et les modifications pulmonaires a etc determine
chez cinquante patients masculins. II y avait une correlation
trts significative entre les scores de neuroticisme et les
modifications postoperatoires. Les patients avec score de
neuroticisme peu eleve avaient une tendance a avoir moins
de douleur, moins d'alternation de la capacite vitale pulmonaire et une frequence moins grande de complications
postoperatoires. L'analyse du score d'extraversion etait
moins conclusive. Une score ilevi
de psychoticisme
s'associa a un score eleve de neuroticisme, mais le psychoticisme n'affecta autrement pas les rtsultats. II n'y avait
pas de correlation significative entre le seuil preoperatoire
de douleur et les facteurs pre-opeiatoires. Les analyses
de Peffet des facteurs pre'-operatoires non-psychologiques
sur la severiti de la douleur post-operatoire et les complications pulmonaires demontrerent des effets moins significatifs que ceux du neuroticisme. Les complications pulmonaires etaient plus frequents chez les patients avec maladie
FACTORS PREDISPOSING TO POSTOPERATIVE PAIN
tboracale pre'-existante et l'incidence de douleur postoperBtoire semblait plus petite chez k s patients qui avaient
recu une analgesie intra-operatoire. On a trouvi une correlation etroite entre revaluation subjective postoperatoire
de la douleur et ralte"ration de la capacity vitale. Le score
de neuroticisme du patient exige une plus grande attention
dans les irudes de douleur postope'ratoire.
FAKTOREN ZUR PRAEDISPOSITION FOR
POSTOPERATIVE SCHMERZZUSTANDE U N D
PULMONALE KOMPLIKATIONEN: EINE
U N T E R S U C H U N G A N MANNLICHEN
PATIENTEN NACH ELEKTIVER
MAGENCHIRURGIE
ZUSAMMENFASSUNG
An funfzig mannlichen Patienten wurden die Beziehungen
zwischen den praeoperativen Faktoren einschliefilich der
Personlichkeit und der Schmerzschwelle sowie postoperativen Schmerzen und pulmonalen Veranderungen festgestellt. Es ergab sich eine auflerordentlich deutliche
Korrelation zwiscben neurotischer Belastung und postoperativen Veranderungen. Die Patienten mit geringem
neurotischen Einschlag hatten zweifellos geringere Schmerzen, eine geringere Verschlechterung der pulmonalen
Vitalkapazitat und eine geringere Zahl postoperativer
Komplikationen. Eine Analyse der Grade von Extroversion
war weniger aufschluflreich. Ein starker psychotischer
Einschlag ging mit einem stark neurotischen Einschlag
einher, psychotische Zustande beeinfluflten jedoch die
Ergebnisse anderweitig nicht. Femer bestand keine deutliche Korrelation zwischen der praeoperativen Schmerzschwelle und postoperativen Faktoren. Die Analyse der
Auswirkungen
nicht
psychologischer
praeoperativer
Faktoren auf den Schweregrad der postoperativen
Schmerzen und die pulmonalen Komplikationen ergab
weniger deutliche Ergebnisse als bei neurotischen Faktoren.
Die pulmonalen Komplikationen waren starker bei Patienten mit praeoperativ vorliegenden Schmerzzustanden im
Thoraxbereich. Die Haufigkeit postoperativer Schmerzen
war geringer bei denjenigen Patienten, welche eine intra-
33
operative Analgesic erhalten harte. Enge Zusammenh&nge
wurden zwischen der postoperativen subjektiven Annnhmr
von Schmerzen und der Verschlechterung der Vitalkapazitat festgestellt. Bei Patienten mit neurotischem
Einschlag bestatigt sich die starkere Beachtung, welche sie
ihren postoperativen Schmerzen zuwenden.
FACTORES PREDISPONENTES A DOLOR
POSTOPERATORIO Y COMPLICACIONES
PULMONARES: U N ESTUDIO D E PACIENTES
VARONES SOMETIDOS A CIRUGIA
GASTRICA E L E C n V A
RESUMEN
Fue determinada en cincuenta pacientes varones la relacidn
entre factores preoperatorios, induyendo la personalidad
y umbral para el dolor, y dolor postoperatorio y cambios
puhnonares. Hubo correlaciones muy significativas entre
las puntuaciones neur6ticas y los cambios postoperatorios.
Los pacientes con una puntuaci6n neur6tica baja tendfan a
tener menos dolor, menos disminuci6n de la capacidad
vital pulmonar y una frecuencia m i s baja de complicaciones
postoperatorias. El anaUsis de las puntuaciones de extroversi6n fue menos concluyente. Una elevada puntuaci6n
psic6tica esta asociada con una puntuacion neur<5tica, pero
el psicoticismo no influyd por lo demas en los resultados.
No hubo ninguna correlaci6n significativa entre el umbral
preoperatorio para el dolor y los factores postoperatorios.
El anilisis de los efectos de factores preoperatorios no
psicoldgicos sobre la severidad del dolor postoperatorio y
complicaciones pulmonares mostro resultados menos
significativos que los anaJisis con netuxnicismo. Las
complicaciones pulmonares eran mis elevadas en los
pacientes con enfermedad tordcica preexistente y la
frecuencia de dolor postoperatorio pareci6 ser menor en
los pacientes que habfan recibido analgesia intraoperatoria.
Se encontro' una estrecha correlacion entre la evaluaci6n
subjetiva postoperatoria de dolor y la disminuci6n de la
capacidad vital. La puntuacion de neuroticismo del paciente
merece una mayor atenci6n en los estudios sobre el dolor
postoperatorio.
SIXTH INTERNATIONAL ANAESTHESIA POSTGRADUATE COURSE
Vienna: May 21-25, 1973
Subject: ACUPUNCTURE AND ANALGESIA
Please address enquiries to:
Frl. E. Maurer,
c/o Wiener Medizinische Akademie,
Alser Strasse 4,
A-1090 Wien, Austria