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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 2, March/April 2020
72
AFRICA
aminotransferase or aspartate aminotransferase
>
150 IU/l), renal
failure (creatinine
>
200
µ
mol/l), or history of seizure, and stroke.
Patients were randomly divided into two groups using sealed,
opaque assignment envelopes as follows: the sevoflurane group,
a sevoflurane-based anaesthetic regimen, and the propofol
group, a propofol-based anaesthetic regimen. In both groups,
anaesthesia was induced with midazolam (0.05 mg/kg) and
sufentanil (1
µ
g/kg). Anaesthesia was maintained with sufentanil
(1
µ
g/kg/h) combined with a continuous intravenous infusion of
propofol (6–10 mg/kg/h) in the propofol group, or with 1–3%
sevoflurane in the sevoflurane group, based on bispectral index
monitoring (maintained at 40–60).
Tracheal intubation was facilitated by administration of
0.15 mg/kg cisatracurium besylate. After endotracheal
intubation, patients were mechanically ventilated on a volume-
controlled mode with fraction of inspired oxygen (FiO
2
) of
0.5, inspiratory:expiratory ratio (I:E) of 1:2, extrinsic positive
end-expiratory pressure (PEEP
e
) of 0 cm H
2
O, frequency of
10–12 breaths/min and tidal volume (TV) of 8 ml/kg. To
keep arterial blood gases within the physiological range, the
respiratory rate (RR) was adjusted with the guidance of end-tidal
CO
2
monitoring and intermittent arterial blood gas analyses.
Standard CPB was established with aortic and both vena
caval cannulations. The priming solution contained Ringer’s
lactate solution, 6% HAES–steril (130/0.4), sodium bicarbonate,
mannitol and heparin with a target of 24–25% haematocrit.
9
During CPB, systemic hypothermia of 28–30°C and a pump
flow of 2.4–2.5 l/min/m
2
were applied. Patients were transferred
to ICU after surgery.
Haemodynamics and respiratory mechanics were recorded
at baseline, before CPB, at 15 min after declamping, and at five,
30 and 60 min after cessation of CPB. The partial pressure of
oxygen/fraction of inspired oxygen (PaO
2
/FiO
2
) was calculated
and recorded at baseline, 15 min after declamping, and at five,
30 and 60 min after cessation of CPB.
Statistical analysis
Results are expressed as mean
±
SD. Data of haemodynamics,
respiratory mechanics and PaO
2
/FiO
2
were analysed using
repeated-measures ANOVA. Differences in clinical characteristics
and parameters at each time point between the groups were
analysed by the independent samples
t
-test for continuous
variables or chi-squared test for categorical variables. Statistical
analysis was performed with the SPSS software package (version
18; SPSS Inc, Chicago, IL). Significance was assumed at
p
<
0.05.
Results
Patient clinical and demographic characteristics, and pre- and
intra-operative features are listed in Table 1. Forty-two patients
were enrolled in the study, with 21 in each group. The sevoflurane
group included 15 males and six females weighing 54.5
±
1.4 kg,
with a mean age of 44.6
±
2.0 years, and the propofol group
comprised 14 males and seven females weighing 54.9
±
2.4 kg,
with a mean age of 45.0
±
2.7 years (
p
=
0.739, 0.859 and 0.909,
respectively, by chi-squared test and independent samples
t
-test).
With regard to NYHA classification, there were five class II
patients in the sevoflurane group and four in the propofol group,
and 16 class III patients in the sevoflurane group and 17 in
the propofol group (
p
=
0.707 by chi-squared test). The intra-
operative characteristics such as CPB time and time of cross-
clamping were not different between the two groups (
p
=
0.433
and 0.340, respectively, by independent samples
t
-test).
Changes in haemodynamic variables are shown in Table 2.
There were no differences in heart rate (73
±
24 vs 73
±
19 beats/
min,
p
=
0.962 by independent samples
t
-test), mean arterial
pressure (71
±
12 vs 75
±
9 mmHg,
p
=
0.258 by independent
samples
t
-test) and central venous pressure (CVP) (6.4
±
6.1
vs 5.0
±
3.9 mmHg,
p
=
0.485 by independent samples
t
-test)
between the sevoflurane and propofol groups at baseline. These
haemodynamic variables were similar in both groups before
CPB, at 15 min after declamping, and five, 30 and 60 min
post-CPB (
p
=
0.787, 0.179, and 0.720, respectively, by repeated-
measures ANOVA).
Changes in respiratory mechanics are shown in Table 3. At
Table 1. Demographic, pre- and intra-operative data of the patients
Variables
S group
(n
=
21
)
P group
(n
=
21
) p-
value
Age (years)
44.6
±
9.2
45.0
±
10.4
0.909
Gender (M/F)
15/6
14/7
0.739
Weight (kg)
54.5
±
6.4
54.9
±
9.1
0.859
NYHA classification (
n
)
Class II
5
4
0.707
Class III
16
17
CPB time (min)
106
±
28
97
±
33
0.433
Time of cross-clamping (min)
63
±
21
58
±
26
0.340
Data are presented as mean
±
standard deviation or number as appropriate.
S: sevoflurane; P: propfol; NYHA: New York Heart Association; CPB: cardio-
pulmonary bypass.
Table 3. Mechanical variables of the study groups
Variables
Baseline Pre-CPB
15 min
after
declamping
5 min
post-CPB
30 min
post-CPB
60 min
post-CPB
PIP, cm H
2
O
Sevoflurane
Propofol
16.6
±
3.3
16.3
±
2.7
16.9
±
3.0
16.6
±
2.1
18.9
±
4.2
16.8
±
2.2
17.0
±
3.8
16.0
±
2.6
16.0
±
2.9
15.5
±
2.1
17.0
±
2.7
16.5
±
1.9
mPaw, cm H
2
O
Sevoflurane
Propofol
6.2
±
1.3
5.8
±
0.7
6.2
±
1.0
5.8
±
0.5
6.5
±
0.8
6.3
±
0.7
6.4
±
1.2
5.9
±
0.8
5.7
±
1.7
5.6
±
0.5
6.4
±
1.6
5.8
±
0.7
iPEEP, cm H
2
O
Sevoflurane
Propofol
2.7
±
0.9
2.5
±
0.5
2.6
±
1.0
2.6
±
0.5
2.9
±
0.9
2.8
±
0.5
3.0
±
0.9
2.5
±
0.5
3.0
±
0.9
2.5
±
0.5
3.1
±
1.0
2.6
±
0.5
DLC, ml/cm H
2
O
Sevoflurane
Propofol
39.6
±
6.6
41.0
±
7.9
39.1
±
4.9
41.7
±
6.3
33.6
±
7.4
41.6
±
5.4
40.3
±
6.0
41.4
±
5.8
41.4
±
4.7
41.2
±
7.3
37.7
±
6.3
38.3
±
6.9
Data are presented as mean
±
standard deviation. TV: tidal volume; PIP: peak inspira-
tory pressure; mPaw: mean airway pressure; iPEEP: intrinsic positive end-expiratory
pressure; DLC: dynamic lung compliance.
Table 2. Haemodynamic variables of the study groups
Variables
Baseline Pre-CPB
15 min
after
declamp-
ing
5 min
post-CPB
30 min
post-CPB
60 min
post-CPB
HR, beats/min
Sevoflurane
Propofol
73
±
24
73
±
19
88
±
20
93
±
17
93
±
20
98
±
16
94
±
19
101
±
7
92
±
17
86
±
13
87
±
15
85
±
15
MAP, mmHg
Sevoflurane
Propofol
71
±
12
75
±
9
62
±
9
58
±
10
56
±
5
60
±
8
63
±
5
64
±
10
66
±
8
69
±
6
68
±
8
74
±
6
CVP, mmHg
Sevoflurane
Propofol
6.4
±
6.1
5.0
±
3.9
6.6
±
4.3
6.2
±
3.2
5.2
±
5.0
6.2
±
3.9
10.2
±
3.1
8.7
±
4.0
10.1
±
2.9
9.5
±
4.0
9.4
±
2.2
10.6
±
3.6
Data are presented as mean
±
standard deviation. HR: heart rate; MAP: mean
arterial pressure; CVP: central venous pressure; CPB: cardiopulmonary bypass.