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.