Abstract
Background and aim of the study: A regular post-cardiac
surgery course does not require a prolonged stay in the cardiac surgery
intensive care unit (ICU). However, a complicated postoperative period,
can lead to prolonged ICU stay and prolonged ventilation, and may
require a tracheostomy. Nonetheless, there is currently no consensus
regarding the proper timing of tracheostomy. Data regarding long-term
outcomes of early versus late tracheostomy are limited. This study
represents the largest single-center experience with post-cardiac
surgery tracheostomy. The aim of this study was to assess the timing of
tracheostomy as a risk factor for mortality.
Methods: This is a retrospective study of prospectively
collected data. Patients were divided into three groups according to the
timing of tracheostomy; early (4-10 days); intermediate (11-20 days) and
late (≤21 days). The primary outcomes were early, intermediate, and
long-term mortality. For statistical analysis we use multivariable Cox
proportional hazards model.
Results: Between 09.2004 and 08.2021, 12,782 patients
underwent cardiac surgery at our institution, of whom 407 (3.18%)
required postoperative tracheostomy. 147 (36.1%) had early, 195
(47.9%) intermediate and 65 (16%) late tracheostomy. The three groups
were similar regarding their baseline characteristics and operative
data. Early, 30-day and in-hospital mortality was similar for all
groups. However, patients, who underwent early- and intermediate
tracheostomy, demonstrating statistically significant lower mortality
after 1- and 5-year (42.8%; 57.4%; 64.6%; and 55.8%; 68.7%; 75.4%,
respectively; p <0.001). In our patient’s cohort Cox
model show age [1.025 (1.014-1.036)] and time to tracheostomy
[0.315 (0.159-0.757)] as significant factor for mortality.
Conclusions: This study demonstrates a relationship
between the timing of tracheostomy after cardiac surgery and mortality:
early tracheostomy within 4-10 days of mechanical ventilation associated
with better intermediate- and long-term survival. Short-term mortality
does not seem to be affected by the timing of tracheostomy. Optimal
timing of tracheostomy requires further evaluation.
Introduction
Most patients undergoing cardiac surgery at our institution have a
postoperative course characterized by a short period of post-operative
mechanical ventilation and a short stay in the cardiac surgery intensive
care unit (CSICU). A complicated postoperative period, on the other
hand, due to infection, cardiac failure, respiratory distress, or other
complications can lead to prolonged ICU stay and prolonged ventilation,
and may require a tracheostomy. With the increased complexity of both
the patient population and surgical procedures performed in recent
years, the number of patients requiring prolonged mechanical ventilation
after cardiac surgery has increased. This is consistent with similar
trends reported in the literature1,2 .
Consequently, many high volume centers have implemented specialized
tracheostomy teams as this has proven to be the safest and most cost
effective model to meet this increased need3.
Tracheostomy may reduce mortality in the subgroup of patients requiring
long-term mechanical ventilation4. Despite the growing
experience in the management of these patients, no consensus exists
regarding the proper timing for tracheostomy. Several studies have
investigated the outcomes of early versus late tracheostomy. However,
early tracheostomy may associated with increased risk of sternal wound
infection5. Nevertheless, data regarding mortality
associated with early versus late tracheostomy is controversial. The aim
of this study was to assess the timing of tracheostomy as a risk factor
for early, intermediate, and late mortality. The second aim of the study
was assessment of the incidence of sternal wound infection (SWI), both
superficial and deep.
Methods
2.1 Study design and setting. This is a retrospective,
observational study of prospectively collected data of patients
undergoing cardiac surgery at a large tertiary care university hospital.
The study was approved by the Sheba Medical Center Institutional Ethics
Committee (Protocol No 4257) and written informed consent was waived due
to the retrospective nature of the study. Data were collected from
collection forms entered into a computerized departmental database. All
patients undergoing cardiac surgery were included in the cohort. The
indications for tracheostomy were as follows: patients were still on
mechanical ventilation at least 4 days; had not successfully passed a
mechanical ventilation weaning screening test or spontaneous breathing
trial; and were expected to require mechanical ventilation for 7 or more
days. Patients were grouped according to time between surgery and
tracheostomy. Based on previous studies6, patients
were divided into three groups according to the timing of tracheostomy;
early group (4-10 days); intermediate group (11-20 days) and late group
(≤21 days). The relative incidence of tracheostomies did not change
during all the years of the study. We compared the groups based on
preoperative demographic data, medical comorbidities and operative data.
Demographic data included sex and age. Medical comorbidities included
chronic obstructive pulmonary disease (COPD), smoking history,
congestive heart failure (CHF) (New York Heart Association [NYHA]
III-IV), cardiac arrhythmia, diabetes mellitus, dialysis-dependent renal
failure, peripheral vascular disease (PVD), left ventricular ejection
fraction (LVEF), previous myocardial infarction (MI), previous
cerebrovascular accident (CVA)/transient ischemic attack (TIA), systemic
and pulmonary hypertension, previous cardiac surgery, priority of
surgery (elective, urgent, or emergent) and logistic and standard
EuroSCORE. Operative data regarding the type of surgery was simplified
into simple (isolated valve or coronary artery bypass graft (CABG)
surgery) versus complex surgery (combined procedures or aortic
procedures). We also compared early (30-day and in-hospital),
intermediate (1-year, 2-year) and late (5-year) mortality since
tracheostomy, which was the primary outcome of the study.
During the initial period of the study, from 01.09.2004 to 31.12.2006,
the CSICU functioned by an open model, under the supervision of a
cardiac surgeon. On 01.01.2007, the CSICU was converted to a semi-closed
model, and since then until the end of this study was supervised by a
board-certified intensivist. In the period between 09.2004 and 01.2007
tracheostomies were performed by open approach by ENT surgeons. From
0.2.2007, all tracheostomies were performed at the bedside by an
experienced thoracic surgical team, which includes 5-6 surgeons and 2-3
anesthesiologists, using the percutaneous dilatation technique
(Portex® Griggs™ Forceps Percutaneous Dilation
Tracheostomy Kits, Smith Medical, St. Paul, MN). During the study, no
other major changes in hospital policy, surgical or anesthesiological
techniques were introduced.