CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 3, May/June 2011
130
AFRICA
Statistical analysis
Data in the text, tables and figures are expressed as mean
±
SEM. Lung tissue PMN counts were evaluated by independent
samples
t
-test. Changes in haemodynamic parameters, respira-
tory mechanics, PVR and AaDO
2
over time between groups
were determined by repeated-measures analysis of variance
(ANOVA). Intra-group data at any given time point for a given
continuous variable were compared with a respective baseline
using the Dunnett
post hoc
test when univariate ANOVA for
repeated measures was significant. Additionally, independent
samples
t
-tests were used to compare the parameters at each time
point between the two groups. Statistical analysis was performed
with SPSS software package, version 11.5 (SPSS Inc., Chicago,
IL). Significance was assumed at
p
<
0.05.
Results
Changes in haemodynamic variables are shown in Table 1. MAP,
HR, CVP, MPAP, mean LAP and CO values did not change
significantly between the groups during the experiment. HR
and CO measured at 5 min after declamping were not analysed
because of comparatively lower cardiac function at the time.
CVP and mean LAP in both groups were within the physiologi-
cal range at the end of the experiment.
At baseline, PIP, MPaw, PEEP
i
and DLC values in the group
treated with isoflurane were comparable to those in the control
group. Following declamping, PIP and MPaw were significantly
increased, and DLC decreased in both the isoflurane and control
groups. Isoflurane pre-treatment did not affect PIP, MPaw, PEEP
i
and DLC significantly, compared to the controls (Table 2).
TABLE 1. HAEMODYNAMICVARIABLES
Parameter
Baseline
Time after aortic declamping (min)
5
31
60
120
180
Mean arterial pressure (mmHg)
Control
82.5
±
5.5 66.2
±
6.6
75.5
±
5.8 60.7
±
4.9* 59.2
±
2.8* 57.0
±
3.8**
Isoflurane
85.8
±
6.9 57.0
±
4.5** 61.0
±
3.1** 64.3
±
7.6
63.8
±
6.8
60.2
±
6.1*
Heart rate (beats/min)
Control
161.0
±
9.8
135.7
±
11.3 119.8
±
10.2** 98.5
±
5.9*** 91.5
±
5.1***
Isoflurane
168.5
±
8.1
140.7
±
13.0 137.3
±
9.5 118.5
±
5.7** 101.3
±
5.5***
Central venous pressure (mmHg)
Control
5.7
±
0.7
4.5
±
0.9
6.7
±
1.0
6.6
±
0.7
7.5
±
1.3
6.7
±
0.6
Isoflurane
7.1
±
0.6
6.6
±
0.7
6.5
±
0.7
7.0
±
0.5
6.7
±
0.4
7.9
±
0.4
Mean pulmonary artery pressure (mmHg)
Control
10.2
±
1.2 12.2
±
1.2
15.7
±
2.6 15.8
±
2.0
15.0
±
1.6
14.7
±
0.6
Isoflurane
10.7
±
1.7
7.8
±
1.9
13.8
±
2.0 13.3
±
1.1
14.7
±
0.9
12.8
±
1.5
Mean left atrial pressure (mmHg)
Control
5.3
±
1.2
4.7
±
0.8
6.5
±
1.2
5.7
±
1.4
7.7
±
1.9
6.3
±
1.5
Isoflurane
6.2
±
1.9
4.2
±
1.5
6.0
±
1.2
5.3
±
0.5
8.0
±
1.2
7.2
±
1.3
Cardiac output (l/min)
Control
3.7
±
0.4
4.0
±
0.5
3.8
±
0.5
2.6
±
0.5
3.0
±
0.6
Isoflurane
3.3
±
0.5
3.6
±
0.6
3.4
±
0.5
3.0
±
0.5
2.6
±
0.4
Data shown are mean
±
SEM. *
p
<
0.05, **
p
<
0.01 and ***
p
<
0.001 compared with baseline.
TABLE 2. RESPIRATORY MECHANICS
Parameter
Baseline
Time after aortic declamping (min)
5
31
60
120
180
Peak inspiratory pressure (cm H
2
O)
Control
10.8
±
1.1
16.3
±
1.5 17.5
±
1.8* 17.8
±
1.9* 19.2
±
2.0** 19.3
±
1.9**
Isoflurane
9.5
±
0.4
13.8
±
1.1 15.2
±
1.5** 16.2
±
1.4** 17.5
±
1.2*** 18.3
±
1.1***
Mean airway pressure (cm H
2
O)
Control
4.7
±
0.3
7.0
±
0.5 7.5
±
0.7*
7.5
±
0.7*
7.8
±
0.7** 7.7
±
0.7**
Isoflurane
4.0
±
0.3
5.3
±
0.2*
#
5.8
±
0.3** 6.2
±
0.4*** 6.7
±
0.2*** 6.7
±
0.4***
Intrinsic positive end expiratory pressure (cm H
2
O)
Control
1.3
±
0.2
1.5
±
0.2 1.5
±
0.2
1.5
±
0.2
1.8
±
0.2
1.8
±
0.2
Isoflurane
1.3
±
0.2
1.0
±
0.3 1.2
±
0.2
1.3
±
0.2
1.3
±
0.2
1.7
±
0.5
Dynamic lung compliance (ml/cm H
2
O)
Control
27.7
±
4.0
16.8
±
1.7* 14.6
±
2.8** 14.3
±
2.1** 13.3
±
1.9** 12.4
±
2.1**
Isoflurane
25.5
±
1.6
16.4
±
2.1** 14.1
±
1.8*** 13.6
±
1.5*** 11.6
±
1.3*** 11.2
±
1.1***
Data shown are mean
±
SEM. *
p
<
0.05, **
p
<
0.01 and ***
p
<
0.001 compared with baseline.
#
p
<
0.05 compared with control at a given time
point.
