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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 4, July/August 2015
160
AFRICA
were collected retrospectively from a computerised clinical
database. We selectively collected the data for 30 patients (group
I,
n
=
30) who were operated on using the on-pump technique
(with cardiopulmonary bypass) and another 30 patients (group
II,
n
=
30) who were operated on using the off-pump technique
(without cardiopulmonary bypass).
Exclusion criteria of the study were as follows: CABG surgery
associated with valvular replacement or any other procedure,
circulatory support with intra-aortic balloon pump before
surgery, pre-operative ejection fraction less than 30%, recent
myocardial infarction (less than three months), emergency
operation, re-operation, pre- or postoperative infection (obtained
from progress notes in the patient files), immunological disease,
tumour, acute or chronic renal failure [pre-operative renal
insufficiency was defined as a serum creatinine level
≥
1.5 mg/dl
(132.6
μ
mol/l) prior to CABG], respiratory impairment, prior
stroke, peripheral vascular disease and coagulopathy. Patients
with postoperative pulmonary, infectious, neurological or
gastrointestinal complications, re-exploration for bleeding, or
cardiac tamponade were also excluded from the study.
Relevant demographic and peri-operative clinical data were
collected for the 60 patients using the above database, and
findings in the two groups (on- and off-pump) were compared.
The specific pre- and intra-operative data obtained for each case
were patient age and gender, history of hypertension, defined as
systolic blood pressure
>
160 mmHg or diastolic blood pressure
>
100 mmHg, diabetes defined as fasting blood glucose levels
>
140 mg/dl (7.77 mmol/l) and the use of oral anti-diabetic
medication or insulin dependency, smoking, unstable angina
pectoris, prior percutaneous transluminal coronary angioplasty,
left ventricular ejection fraction, presence or absence of left main
coronary artery disease, and number of grafts per operation.
The postoperative data collected were mechanical ventilation
time, need for inotropic or intra-aortic balloon pump support,
peri-operative myocardial infarction (immediate postoperative
period), dysrythmias, length of stay in the intensive care unit
(ICU) and overall hospital stay.
Pre-operative, and first and fifth postoperative day total
leukocyte counts and differential counts (neutrophils and
lymphocytes) were taken from patient files in our hospital
archives. The calculation of N:L ratios was entrusted to one of
our authors who was blinded to the neutrophil and lymphocyte
samples from the two groups.
Surgical procedure
All patients were given the same anaesthesia protocol. They
were pre-medicated with midazolam (0.05 mg/kg IV). On the
operating table, cannulae were inserted in a peripheral vein, the
radial artery and the right jugular vein. Standard monitoring
included pulse oximetry, leads II and V5 of the ECG for heart
rate and automated ST-segment trend analysis, continuous
measurements of arterial and central venous pressures,
nasopharyngeal temperature, and end-tidal capnography.
A balanced anaesthetic technique included fentanyl (bolus
of 1–2 mg/kg followed by an intermittent bolus of 1–2 mg/
kg/h), etomidate (bolus of 0.2—0.3 mg/kg), esmeron (bolus of
1 mg/kg and an intermitant bolus of 0.3 mg/kg/h) and inhaled
sevofluorane (2–3% in the pre-bypass period and 1–1.5% in
the bypass period). Ventilation was modified in each patient
to reach partial arterial oxygen pressure above 150 mmHg and
partial arterial carbon dioxide pressure above 45 mmHg. A
conventional median sternotomy was performed in all patients.
In group I (on-pump), cardiopulmonary bypass (CPB) was
established in a standardised manner with the use of a roller
pump and non-pulsatile flow (2.4 l/m
2
/min). A heparinisation
protocol of 300 U/kg was followed to maintain clotting time
at longer than 400 s. Patients were cooled to 32°C when distal
anastomosis was being performed, and were warmed to 36°C
before weaning from CPB.
After aortic cross-clamping, cold-blood cardioplegia was
accomplished with anterograde delivery through the aortic root
for initial diastolic arrest of the heart, and intermittently after
each distal anastomosis. A final dose of ‘hot-shot’ cardioplegia
was also administered antegradely just before the aorta was
unclamped. Protamine was used to reverse the effects of
heparinisation.
In group II (off-pump), by adjusting the operating room
temperature, hypothermia was avoided. Partial anticoagulation
was accomplished with 1–2 mg/kg body weight of heparin until
a target activated clotting time (ACT) of 250 s was achieved.
Octopus 4 (Medtronic Inc, Minneapolis, MN, USA) was used as
cardiac stabiliser.
In order to obtain a bloodless anastomotic field after
arteriotomy, we did the following: after opening the distal artery,
intracoronary shunts (Clearview intracoronary shunt, Medtronic
Inc, USA) were inserted into the coronary artery for each
anastomosis, which were 1.5, 2.0 or 2.5 mm in size according
to the coronary artery lumens, and shunts were removed after
the last suture just before tying. Heparin was not neutralised by
protamine sulfate at the end of the operation.
Statistical analysis
The values obtained from the groups were compared to evaluate
N:L ratios after coronary artery surgery with or without
cardiopulmonary bypass. Statistical analysis was performed with
SPSS version 15.0 (SPSS, Inc, Chicago, IL) software. Compliance
of variables with a normal distribution was analysed with visual
(histogram and probability plots) and analytical methods (the
Kolmogorov–Smirnov test). Descriptive analyses were provided
as mean and standard deviation.
Relationships between cardiopulmonary bypass and N:L
ratios and pre-, intra- and postoperative factors were analysed
using different methods: the independent samples
t
-test for
normally distributed continuous variables (expressed as mean
±
SD), and chi-square and Fisher’s exact tests for categorical
variables, as appropriate. The results were assessed within a 95%
reliance and at a significance level of
p
<
0.05.
Results
This study comprised 60 patients who underwent CABG surgery.
Thirty of the patients were operated on with CPB (group I) and
the other 30 without bypass (group II). The number of bypassed
grafts were different between the two groups, being statistically
higher in group I than in group II (3.20
±
0.88 and 1.93
±
0.78,
respectively,
p
<
0.001). Hospital stay was longer in group I
(8.97
±
2.39 days) than in group II (5.90
±
2.07 days), and this
difference was also statistically significant (
p
<
0.001). Except