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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 1, January/February 2018
AFRICA
23
Inc, Chicago, IL, USA). Group comparisons of categorical data
were assessed using Pearson’s chi-squared and Fisher’s exact tests
and chi-squared trend analysis. Because the permanent variables
did not have normal distributions (Kolmogorov–Smirnov test,
p
<
0.05), the Mann–Whitney
U
-test was used to compare the
two groups, and the Kruskal–Wallis
H
-test (
post hoc
Bonferroni
corrected Mann–Whitney
U
-test) was used to compare multiple
groups. The associations between SIRS and other variables were
evaluated using Spearman’s rho correlation analysis.
Results
We found no statistically significant differences among the groups
regarding gender, incidence of diabetes, chronic obstructive lung
disease, chronic renal failure or prior open-heart surgery (
p
>
0.05). Smoking rates, pre-operative haemoglobin levels, and
body surface area were significantly lower in group 3 than in the
other groups, and the incidence of hypertension was significantly
lower in group 1 compared to the other groups (
p
<
0.05). The
average EuroSCORE value was higher in group 3 than in the
other groups (
p
<
0.05; Table 1).
Comparisons of off-pump bypass surgery rates, CPB time,
cross-clamping time, intra-aortic balloon pump use and revision
ratios revealed no statistically significant differences among
the groups (
p
>
0.05). However, the amount of postoperative
drainage and peri-operative blood transfusions were significantly
higher in group 2 than in the other groups (
p
<
0.05; Table 2).
We found no significant differences in length of intensive care
unit or hospital stay, incidence of neurological complications,
and mortality rates among the groups (
p
>
0.05). However,
the incidence of SIRS was significantly higher in group 3 than
in group 1 (
p
<
0.05; Table 3), and the weaning period was
significantly shorter in group 1 than in the other groups (
p
<
0.05).
Analysis of the predictive factors for SIRS revealed a
statistically significant but weak positive correlation of SIRS
with age, EuroSCORE value, on-pump CABG and intra-aortic
balloon pump use. By contrast, we found a statistically significant
but weak negative correlation of SIRS with pre-operative
haemoglobin levels and off-pump CABG (
p
<
0.05). No other
statistically significant relationships were found between SIRS
and the other variables (
p
>
0.05; Table 4).
Discussion
CPB itself may trigger systemic inflammation; however its role
is controversial because inflammation may be induced by several
factors other than CPB. Tissue damage, endotoxaemia and
contact of blood with a non-endothelial surface during CBP
are thought to trigger systemic inflammation during open-heart
surgery,
8,9
which may lead to SIRS.
The reported incidence of SIRS during the 24-hour
postoperative period widely varies from 27 to 96%; this variability
Table 1. Demographic data
Parameters
Group 1
(n
=
61)
n
(%)
Group 2
(
n
=
83)
n
(%)
Group 3
(
n
=
85)
n
(%)
p-
value
Age (years)
36.7
61.3
77.9
Male gender
49 (80.3)
63 (75.9)
55 (64.7)
0.083
Diabetes mellitus
14 (23)
36 (43.4)
21 (24.7)
0.937
COPD
1 (1.6)
3 (3.6)
6 (7.1)
0.107
Hypertension
17 (27.9)
49 (59)
54 (63.5)
0.000
CRF
4 (6.6)
3 (3.6)
1 (1.2)
0.082
Smoking
35 (57.4)
42 (50.6)
24 (28.2)
0.001
Redo surgery
0
0
2 (2.4)
0.107
EuroSCORE
1.95 ± 2.07
3.69 ± 2.24
5.2 ± 1.7
0.000
Pre-operative Hb 13.02 ± 1.89 12.57 ± 1.71 11.93 ± 1.49 0.000
BSA
1.88 ± 0.18
1.77 ± 0.16
1.68 ± 0.16 0.000
COPD: chronic obstructive pulmonary disease, CRF: chronic renal failure, Hb:
haemoglobin, BSA: body surface area.
Table 2. Peri-operative data
Parameters
Group 1
(
n
=
61)
n
(%)
Group 2
(
n
=
83)
n
(%)
Group 3
(
n
=
85)
n
(%)
p
-value
Off-pump CABG
15 (24.6)
20 (24.1)
19 (22.4)
0.745
CPB time (min)
82.21 ± 49.45 88.05 ± 29.05 83.58 ± 29.76 0.105
Cross-clamping time (min) 45.9 ± 30.62 46.53 ± 19.17 43.72 ± 18.78 0.536
Revision
5 (8.2)
8 (9.6)
11 (12.9)
0,343
Drainage (ml)
581 ± 294 480 ± 268 670 ± 501 0.004
Blood transfusion (IU)
2.25 ± 1.45 1.7 ± 0.95 3.26 ± 3.38 0.045
IABP
8 (13.1)
6 (7.2)
15 (17.6)
0.321
CABG: coronary artery bypass graft, CPB: cardiopulmonary bypass, IABP:
intra-aortic balloon pump.
Table 3. Postoperative data
Parameters
Group 1
(
n
=
61)
n
(%)
Group 2
(
n
=
83)
n
(%)
Group 3
(
n
=
85)
n
(%)
p
-value
Weaning period (h)
10.67 ± 7.55 13.9 ± 10.01 14.28 ± 10.25 0.000
ICU stay (day)
2.92 ± 1.45 3.2 ± 2.69 3.52 ± 2.42 0.346
Hospital stay (day)
7.41 ± 3.96 8.59 ± 12.22 7.32 ± 3.12 0.736
Neurological complications 1 (1.6)
2 (2.4)
2 (2.4)
0.786
Mortality
3 (4.9)
5 (6.0)
12 (14.1)
0.083
SIRS
42 (68.9)
70 (84.3)
78 (91.8)
0.000
ICU: intensive care unit, SIRS: systemic inflammatory response syndrome.
Table 4. Predictive factors for SIRS following CABG
Parameters
SIRS
r
p
-value
Age
0.254
0.000
Diabetes mellitus
0.103
0.121
COPD
–0.017
0.799
Smoking
0.028
0.672
CRF
–0.040
0.544
Hypertension
0.103
0.119
Redo surgery
–0.082
0.216
EuroSCORE
0.179
0.007
Ejection fraction
–0.037
0.580
Neurological complications
0.068
0.308
Hospital stay
–0.015
0.837
Pre-operative haemoglobin level
–0.164
0.013
Body surface area
–0.073
0.272
Off-pump CABG
–0.186
0.005
On-pump CABG
0.208
0.002
CPB period
0.140
0.062
Cross-clamping period
0.138
0.065
Intra-aortic balloon pump use
0.138
0.037
Drainage amount
0.048
0.471
Blood transfusion
0.060
0.531
Revision
–0.035
0.602
COPD: chronic obstructive pulmonary disease, CRF: chronic renal failure,
CABG: coronary artery bypass grafting, CPB: cardiopulmonary bypass, SIRS:
systemic inflammatory response syndrome.