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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018
382
AFRICA
to conduct the study was obtained from the Human Research
Ethics Committee (medical) and other relevant authorities.
Informed consent was not required as this was a retrospective
study. Data were collected by one author (CTB). Patient
confidentiality was maintained by assigning numbers to patient
data, and raw data were accessed by the author and supervisor.
Data were collected for patients younger than 18 years of
age who underwent cardiac surgery on CPB for congenital heart
disease during the period 1 January to 31 December 2014. The
charts of the anaesthetists, perfusionists and intensive care unit
were reviewed for relevant data. Data collected included patient
demographics, cardiac lesion and operation, pre-operative
platelet count, peri-operative anticoagulation therapy, peri-
operative haemoglobin level, CPB time, aortic cross-clamp
(AOX) time and intra-operative blood products used.
Blood products transfused to patients are represented in units,
as the practice in the department is not to document products
in millilitres. The practice also involves transfusion of products
over a period of time, commencing intra-operatively and into the
postoperative period [no longer than four hours for red packed
cells (RPC) and 30 minutes after thawing for fresh frozen plasma
(FFP)]. A unit of RPC has a volume of approximately 300 ml,
FFP approximately 225 ml, platelets approximately 160 ml, and
cryoprecipitate approximately 15 ml.
Patients who were Jehovah’s Witness, and patients with
missing or illegible data were excluded.
Statistical analysis
Data collection, management and processing were performed
using Microsoft
®
Excel for Windows, and the analysis was
conducted using Stata
®
14 (StataCorp.2015, Stata Statistical
Software: Release 14. College Station, TX: StataCorp LP).
Descriptive analysis was done using tables of frequencies
and percentages, mean (standard deviation: SD) and median
(interquartile range: IQR) where appropriate, and data are
presented according to RACHS categories, as this denotes the
complexity of the cardiac surgery.
20
The Kruskal–Wallis and one-way Anova analysis of variance
were conducted to determine the median or mean differences
of clinical variables across the RACHS and weight categories.
Dunn’s comparison with the Holm–Sidak stepwise adjustment
was performed as a
post hoc
test to the Kruskal–Wallis to find
where the statistically significant difference was between the
groups. A pairwise correlation test was performed to assess the
linear relationship between RPC, FFP and CPB time. A
p
-value
<
0.05 was considered statistically significant.
Results
A total number of 121 patients were eligible to be included in
the study. Of these, 16 patients were excluded due to missing
data pertaining to pre-operative results (four), anaesthetic
charts (two), perfusionist charts (five) and intensive care unit
charts (five). There were six (5.7%) redo surgery patients who
were included in the study as their primary surgery had been
undertaken outside of the study period. No patients were
included more than once in the study.
The patient demographics are presented in Table 1, according
to their respective RACHS categories. There were no patients in
RACHS category 5; therefore, the category is excluded from the
tables.
Pre-operative haemoglobin and platelet counts are presented
in Table 2. There was no significant difference in pre-operative
platelet count and haemoglobin level across the RACHS
categories.
Records showed that aspirin was administered pre-operatively
in only three (2.9%) patients but with no doses documented,
and these patients where in RACHS category 2. A bolus dose
of 300–500 IU/kg heparin was given by the anaesthetist before
initiation of CPB. The perfusionists administered additional
heparin during CPB with a mean (SD) dose of 1.8 (1.4) mg/kg.
The type of CPB clear prime fluid for the 105 patients was
not clearly stated on the charts. Ten out of 105 (9.5%) patients
did not receive clear prime fluid on CPB. The median (IQR)
fluid volume used was 800 (500–1 000) ml. Albumin was added
to the CPB in 32 (30.5%) patients at a mean (SD) dose of 9.7
(4.1) ml/kg.
The median values for AOX and CPB time in minutes
between the RACHS categories are shown in Table 3. AOX and
CPB times were statistically significantly different between the
RACHS scores. There was a statistically significant relationship
Table 1. Demographics according to RACHS category
Parameters
RACHS 1 RACHS 2 RACHS 3 RACHS 4
Demographics
Patients,
n
(%)
13 (12.4)
62 (59)
27 (25.7)
3 (2.9)
Male,
n
(%)
5 (9.4)
34 (64.2)
12 (22.6)
2 (3.8)
Female,
n
(%)
8 (15.4)
28 (53.8)
15 (28.8)
1 (1.9)
Age (years),
median (IQR)
5.5 (3.5–6.25)
4 (1–6)
4 (1–7)
0.08 (0.08–1.04)
Weight (kg),
median (IQR)
18 (13–20)
12 (9–19)
13 (8–22)
3.4 (3.3–3.45)
Congenital heart lesions,
n
(%)
ECD
11 (25.6)
21 (48.8)
11 (25.6)
0 (0)
GVA
2 (28.6)
0 (0)
2 (28.6)
3 (42.9)
TOF
0 (0)
28 (100)
0 (0)
0 (0)
Valve abnormal
0 (0)
13 (56.5)
10 (43.5)
0 (0)
CC abnormal
0 (0)
0 (0)
4 (100)
0 (0)
ECD, endocardial cushion defects; GVA, great vessel anomalies; TOF, tetral-
ogy of Fallot; CC, cardiac chamber; RACHS, risk-adjusted classification for
congenital heart surgery.
Table 2. Pre-operative platelet count and haemoglobin level
Parameters,
mean (SD) RACHS 1 RACHS 2 RACHS 3 RACHS 4
p
-value
Platelets
(× 10
9
cells/l)
317.3 (89.8) 294.8 (128.7) 327 (144.6) 277.7 (96.4) 0.855
Hb (g/dl)
12.7 (1.3)
14.7 (3.7)
14.3 (3.6)
11.1 (2.6)
0.16
RACHS, risk-adjusted classification for congenital heart surgery; Hb, haemo-
globin.
Table 3. CPB and AOX time in minutes according to RACHS category
Parameter,
median (IQR) RACHS 1 RACHS 2 RACHS 3 RACHS 4
p
-value
AOX time (min)
18.5
(11–40.5)
76
(50–123.5)
89
(57–120)
157
(112–193)
0.0002*
CPB time (min)
55
(50–97.5)
123
(94.5–89.5)
143
(100–198)
294
(257–447)
0.0001*
*
p
<
0.05; AOX, aortic cross-clamp; CPB, cardiopulmonary bypass; RACHS,
risk-adjusted classification for congenital heart surgery.