CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 4, May 2012
212
AFRICA
Risk factors for the development of pneumonia post
cardiac surgery
AE TOPAL, MN EREN
Abstract
Objectives:
Postoperative pneumonia is a devastating compli-
cation after cardiac surgery that increases morbidity and
mortality. The objective of this study was to identify potential
risk factors for the development of nosocomial pneumonia
post cardiac surgery by the way of logistic regression analysis.
Design:
Data of the last 162 patients undergoing cardiac
surgery before November 2009 were retrospectively collected
and analysed.
Results:
The mean age of the patients was 65.57
±
10.48 years
and 83 (51%) were male. Postoperative pneumonia was
diagnosed in 21 (13%) patients. The mean remaining time
in the intensive care unit and mean length of hospitalisa-
tion were longer for patients with postoperative pneumonia.
Pre-operative heart rate, previous diabetes mellitus, previ-
ous chronic obstructive pulmonary disease, postoperative
urea, creatinine and potassium levels, extubation time,
postoperative atrial fibrillation, and number of units of
transfused packed red blood cells (pRBC) and fresh frozen
plasma were associated with higher occurrence of postopera-
tive pneumonia on univariate analysis.
Conclusions:
On logistic regression analysis, pRBC transfu-
sion, previous chronic obstructive pulmonary disease and
postoperative atrial fibrillation remained as independent
predictors for the development of postoperative pneumonia.
Keywords:
cardiac surgery, pneumonia, atrial fibrillation, trans-
fusion, chronic obstructive pulmonary disease
Submitted 29/7/10, accepted 17/1/12
Cardiovasc
J Afr
2012;
23
: 212–215
DOI: 10.5830/CVJA-2012-005
Despite the progress made in surgery and anaesthesia, the risk of
developing nosocomial infections remains a real threat as more
patients of greater age and with more co-morbidities are operated
on.
1
Particularly cardiac surgery creates a high risk for the
development of hospital infections and among these, pneumonia
plays an important role as it increases morbidity and mortality by
causing pulmonary dysfunction or multi-organ failure.
Patients undergoing cardiovascular operations are currently
older and with serious co-morbid disease. Compared to their
younger counterparts, heart surgery in elderly patients has been
implicated in the higher risk of mortality and recurrent pulmonary
complications.
2
Moreover, emergence of antibiotic-resistant
pathogens increases the incidence of refractory pneumonia.
The aim of our study was to identify potential risk factors for
the development of nosocomial pneumonia post cardiac surgery
and thus contribute to decreasing the incidence of pneumonia by
identifying preventable risk factors.
Methods
This retrospective study was performed on the last 162 patients
who underwent cardiac surgery (coronary artery bypass graft
surgery, valve-replacement surgery) at our reference centre
up to November 2009. The exclusion criteria were usage of
immunosuppressive agents and an identifiable infection prior to
surgery.
All patients received standardised anaesthetic management.
In the operating room, leads II and V5 on the electrocardiogram
(ECG) and arterial blood pressure were continuously monitored.
Anaesthesia was induced with intravenous midazolam (0.03–0.07
mg/kg), sufentanil (1.5–3.0 mg/kg) and rocuronium bromide
(0.9 mg/kg), and maintained with sevoflurane (0.8–1.5%) and
continuous infusion of sufentanil (0.5–1.5 mg/kg/h).
All surgical procedures were performed through a median
sternotomy. All patients included in the study received
prophylactic administration of intravenous cefazolin peri-
operatively (1 g intravenously 30 minutes prior to the first
incision, every eight hours during surgery and postoperatively
for three days).
Pneumonia was considered clinically present as a new
radiographic pulmonary infiltrate, consolidate, cavitation or
pneumatocele in the presence of the following conditions:
fever (
>
38°C) without other recognised causes, leucocytosis (
>
12 000/
μ
l) or leucopenia (
<
4 000/
μ
l) and new-onset purulent
sputum with a Gram-positive stain finding.
Possible risk factors and outcomes associated with pneumonia
post cardiac surgery were analysed, including pre-operative
variables [age, gender, heart rate, mean blood pressure, body
surface area, urea, creatinine and potassiumlevels, co-morbidities,
NYHA class, and left ventricular ejection fraction (LVEF)],
operative variables [on/off pump surgery, cross-clamp time,
cardiopulmonary bypass (CPB) time, total operation time, and
need for intra-operative inotropic support], and postoperative
variables [extubation time, chest tube drainage, number of
units of transfused packed red blood cells (pRBC) and fresh
frozen plasma (FFP), urea, creatinine and potassium levels, and
postoperative atrial fibrillation (AF)].
Statistical analysis
The normality of the variables was analysed by Kolmogorov–
Smirnov test. Continuous variables are presented as means with
standard deviations and were compared among groups using
the Student’s
t-
test or Mann-Whitney U-test when appropriate
(non-parametric data). Dichotomous variables are presented
as percentages and were compared among groups using a
Chi-square or Fisher exact test when appropriate.
Cardiovascular Surgery Department, Dicle University
Medical Faculty, Diyarbakır,Turkey
AE TOPAL, MD,
,
MN EREN, MD
