ATS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Jai H. Lee
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Konstantakos, A. K.
Right arrow Articles by Lee, J. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Konstantakos, A. K.
Right arrow Articles by Lee, J. H.

Ann Thorac Surg 2000;69:1842-1845
© 2000 The Society of Thoracic Surgeons

Original articles: Cardiovascular

Optimizing timing of early extubation in coronary artery bypass surgery patients

Anastasios K. Konstantakos, MDa, Jai H. Lee, MDa

a Division of Cardiothoracic Surgery, University Hospitals Heart Institute, University Hospitals of Cleveland, Cleveland, Ohio, USA

Address reprint requests to Dr Lee, Division of Cardiothoracic Surgery, University Hospitals of Cleveland, 11100 Euclid Ave, Cleveland, OH 44106
e-mail: jhl6{at}po.cwru.edu


   Abstract
Top
 Abstract
Introduction
 Patients and methods
 Results
 Comment
 References
 
Background. This study was designed to assess the safety and efficacy of extubation performed within 4 hours of the patient’s arrival in the surgical intensive care unit after coronary artery bypass graft surgery.

Methods. A matched retrospective cohort study was performed including 412 consecutive patients undergoing isolated coronary artery bypass graft surgery between January 1996 and December 1997, constituting the experience of a single surgeon (J.H.L.). Early extubation (defined as extubation within 8 hours of arrival at the surgical intensive care unit) was achieved in 308 of 412 patients (75%). Patients extubated in fewer than 4 hours after arrival (n = 200) were compared with patients extubated within 4 to 8 hours (n = 108).

Results. Four deaths occurred in 412 patients, for an overall operative mortality rate of 1.0%. Patients extubated in fewer than 4 hours were younger than those extubated 4 or more hours after admission (62 versus 67 years old, respectively; p = 0.001), more likely to be male (74% versus 63%, p < 0.05), and had shorter aortic cross-clamp times (49.4 ± 15.0 versus 53.5 ± 14.0 minutes, p < 0.05) and cardiopulmonary bypass (CPB) times (65.2 ± 18.6 versus 72.1 ± 19.1 minutes, p < 0.05) compared to patients extubated later. Moreover, patients extubated in fewer than 4 hours had a shorter surgical intensive care unit length of stay (33.8 ± 25.7 versus 43.1 ± 43.0 hours, p < 0.05) and shorter postoperative length of stay (5.4 ± 2.4 versus 6.2 ± 2.6 days, p = 0.01) than those extubated later.

Conclusions. Extubation in fewer than 4 hours may offer a substantial advantage in terms of accelerated recovery compared with extubation within 4 to 8 hours. Very few differences in clinical parameters were noted between the two groups we studied, suggesting that efforts to reduce extubation times further might be worthwhile.


   Introduction
Top
 Abstract
 Introduction
Patients and methods
 Results
 Comment
 References
 
The challenge mandated by health care reform to continue to achieve excellence in postoperative outcomes while reducing costs has significantly affected care of the cardiac surgery patient. Fast-track protocols designed to shorten length of stay (LOS) have now become commonplace [1–3]. Specifically, a key component of such protocols is emphasis on early extubation following arrival at the surgical intensive care unit (SICU) [4].

Recent studies have indicated that early extubation can lead to a shortened LOS and help reduce total costs following coronary artery bypass graft surgery (CABG) [3]. However, significant variation exists in the definition of the term early extubation. For example, Arom [2] defined early extubation as endotracheal tube removal within 12 hours of arrival at the SICU, while Higgins [4] referred to early extubation as extubation within 3 to 10 hours of SICU arrival and Prakash [5] defined early extubation as endotracheal tube removal within 3 hours of surgery. Recently we showed that extubation within 8 hours of arrival at the SICU was associated with a significant LOS reduction in both young and elderly patients [6]. However, preliminary analysis of our earlier data suggested that even earlier extubation was perhaps safe and feasible. This study was thus undertaken (1) to determine if the timing of early extubation could be accelerated to fewer than 4 hours after SICU arrival, (2) to determine which demographic and intraoperative parameters were associated with shortened extubation times, and (3) to assess the impact of shortened extubation times on SICU and overall hospital LOS.


   Patients and methods
Top
 Abstract
 Introduction
 Patients and methods
Results
 Comment
 References
 
The study included all 412 patients who underwent isolated CABG (comprising urgent, emergent, and catheterization salvage procedures, as well as reoperations) between January 1996 and December 1997 at University Hospitals of Cleveland; this group constituted the experience of a single surgeon (J.H.L.). The study population consisted of 308 patients who underwent early extubation (defined as extubation within 8 hours of SICU admission). Patients were divided into two groups: those extubated in fewer than 4 hours (n = 200) and those extubated within 4 to 8 hours (n = 108) following SICU admission.

Surgical and anesthetic technique
All patients underwent surgery by way of median sternotomy with standard cardiopulmonary bypass techniques with moderate hemodilution (hematocrit range, 21% to 27%). Cardiopulmonary bypass was instituted using an ascending aortic cannula and a two-stage venous cannula. The perfusion temperature was allowed to decrease to 32°C, and cooling to lower temperatures was not done.

The initial heparin dose was 250 to 300 U/kg, and 5000 U was added to the pump prime. Additional heparin was administered as necessary to maintain activated coagulation times greater than 480 seconds. Myocardial protection was achieved with antegrade and retrograde delivery of tepid blood cardioplegic solution. In patients with ongoing ischemia, an initial warm induction dose of cardioplegic solution was administered. All distal and proximal anastomoses were constructed during the rewarming phase, so that a perfusion temperature of 37°C was achieved at the time of administration of the terminal substrate-enriched dose of warm cardioplegic solution.

The anesthetic technique was geared toward facilitating early extubation regardless of preoperative comorbid conditions. Anesthetic induction was achieved with either etomidate or sodium thiopental, supplemented with midazolam and fentanyl or sufentanil. Anesthetic maintenance was with isoflurane, fentanyl or sufentanil, and midazolam, with or without propofol at the discretion of the attending anesthesiologist. Pancuronium or vecuronium were used for muscle relaxation. Total fentanyl and sufentanil doses were 10 to 25 µg/kg and 2 to 3 µg/kg respectively. Total midazolam doses were less than 0.1 mg/kg.

Intraoperative and postoperative management
Intraoperative monitoring included radial and pulmonary arterial pressures, electrocardiography, esophageal temperature, end-tidal capnography, and pulse oximetry. All patients were rewarmed to an esophageal temperature of 37°C before the discontinuation of CPB. Patients with serum creatinine values greater than 1.6 mg/dL received renal dose dopamine which was continued into the postoperative period for 24 to 36 hours.

Postoperative pain was managed with morphine sulfate. Approximately 85% of patients were sedated short-term with low-dose propofol infusions (10 to 50 µg· kg-1 · min-1), titrated to achieve a score of 3 on the Ramsay scale (patient comfortably asleep or drowsy but responding easily to commands). Patients were weaned from the ventilator using a standard protocol and extubated when standard criteria were met [7].

All data were prospectively collected on standardized forms and entered into a computerized database as part of The Society of Thoracic Surgeons National Database (Summit Medical Systems Inc, Minneapolis, MN). All data are expressed as mean plus or minus standard deviation or percentages where appropriate. Clinical and operative differences between the two groups were evaluated for statistical significance with t tests; confidence intervals were used to express the difference between the two means.


   Results
Top
 Abstract
 Introduction
 Patients and methods
 Results
Comment
 References
 
Significant demographic, clinical, and catheterization data for the study group are shown in Table 1. The mean age of the cohort extubated in fewer than 4 hours was 62 years, and the mean age of the cohort extubated within 4 to 8 hours was 67 years (p < 0.001). There were fewer women in the group extubated in fewer than 4 hours than in the group extubated within 4 to 8 hours (37% versus 26%, respectively; p < 0.05). There was no difference between the groups in the prevalence of diabetes mellitus, chronic obstructive pulmonary disease, peripheral vascular disease, hypertension, congestive heart failure, cerebral vascular disease, or chronic renal failure, nor was there any difference in the incidence of unstable angina or recent (< 7 days) myocardial infarction. With respect to cardiac parameters, both cohorts had similar preoperative ejection fractions, degree of left main coronary artery disease, and incidence of cardiogenic shock. There was a lower incidence of coronary bypass reoperations in the patients extubated in fewer than 4 hours than in those extubated within 4 to 8 hours (3.0% versus 9.2%, respectively; p < 0.01).


View this table:
[in this window]
[in a new window]
  		Table 1. Patient Demographics and Clinical Data

 
Intraoperative and procedure details for the early extubation group are listed in Table 2. Cross-clamp and CPB times were dissimilar in the groups. The left internal mammary artery was used in more the 90% of all patients. The total number of grafts performed was similar in the both groups. The overall surgical mortality rate was 1.0% (4 of 412). No deaths occurred among patients who underwent extubation in fewer than 4 hours or in 4 to 8 hours. The relationship of age to extubation in fewer than 4 hours is shown in Figure 1. With increasing age, the percentage of patients who were extubated in fewer than 4 hours showed a steady decline. For example, 70% of patients younger than 50 years compared with 33% of patients older than 80 years were extubated successfully in fewer than 4 hours of SICU arrival.


View this table:
[in this window]
[in a new window]
  		Table 2. Intraoperative Data

 


View larger version (13K):
[in this window]
[in a new window]
  		Fig 1. Percentage of patients extubated in fewer than 4 hours versus age.

 
Postoperative patient outcomes are listed in Table 3. The average times of intubation in the earlier and later extubation groups were 2.7 ± 1.2 hours and 6.2 ± 1.1 hours, respectively (p < 0.001). The overall reintubation rate was less than 1%. The incidence of atrial fibrillation did not differ significantly between the two groups (16.5% versus 22.9%, p = NS). The SICU LOS was 33.8 ± 25.7 hours in the group extubated in fewer than 4 hours compared with 43.1 ± 43.3 hours in the group extubated within 4 to 8 hours (p < 0.01). A higher percentage of patients who were extubated in fewer than 4 hours compared with those who were extubated later were discharged from the hospital in 5 days or fewer (69% versus 55%, p < 0.01). Moreover, the overall postoperative LOS was shorter in the cohort of patients extubated in fewer than 4 hours compared with those extubated later (5.4 ± 2.4 days versus 6.2 ± 2.6 days, p = 0.01).


View this table:
[in this window]
[in a new window]
  		Table 3. Postoperative Data

 

   Comment
Top
 Abstract
 Introduction
 Patients and methods
 Results
 Comment
References
 
Recent advances in surgical and anesthetic techniques have facilitated early hospital discharge following CABG [1, 4]. Such fast-track protocols have placed a significant emphasis on prompt extubation upon arrival at the SICU. As a fundamental component of the fast-track protocols, early extubation has been shown to expedite SICU discharge as well as overall LOS, thus resulting in a net cost-savings [1, 3]. However, the timing of early extubation has varied among different reports, and a precise definition of early extubation has not been established. This study has defined early extubation as endotracheal tube removal within 8 hours of SICU admission and has shown that even earlier removal of the endotracheal tube (ie, within fewer than 4 hours) may further reduce SICU and overall LOS.

Analysis of the preoperative and intraoperative demographics showed that although there was a higher percentage of men and a lower incidence of reoperative CABG patients in the cohort extubated in fewer than 4 hours, no other criteria analyzed were able to differentiate between patients extubated in fewer than 4 hours and those extubated later. A statistically significant trend towards shortened CPB and aortic cross-clamp times was noted among patients extubated in fewer than 4 hours. It appears that although very few demographic parameters can distinguish patients capable of undergoing extubation in fewer than 4 hours, intraoperative factors such as CPB and aortic cross-clamp times may play important roles in allowing patients to be extubated earlier in the SICU. Thus, in patients undergoing early extubation, a decreased SICU LOS is associated with a decreased total LOS, which is associated with significant cost savings [3]. Thus, efforts should continue to be made to extubate postoperative coronary bypass graft patients as soon as possible in the SICU, particularly those who are younger and have had shorter intraoperative courses. It should be noted that in our institution the SICU is physically separate from the telemetry ward and therefore a full telemetry ward may create a backlog of patients in the SICU. Thus factors other than the physiologic readiness of the patient may affect SICU LOS and may explain why the average SICU LOS is greater than 30 hours in this cohort of patients.

Variables that have been shown in some studies to affect intubation times include older age, female gender; presence of unstable angina, hemodynamic instability, abnormal temperature, or renal insufficiency; use of preoperative diuretics, postoperative intraaortic balloon counterpulsation, and banked blood transfusion; and longer duration of CPB. [2, 8–10]. Thus it is not surprising that analysis of preoperative and intraoperative variables in this study demonstrates differences among the cohort of patients extubated in fewer than 4 hours after SICU admission versus those extubated in 4 to 8 hours. The earlier extubation group tended to be younger (62.3 versus 67.0 years of age, p < 0.05) and was less likely to be female (25% versus 37%, p < 0.05). Statistically significant decreases in CPB and aortic cross-clamp times were also noted in the earlier extubation group.

There are several potential benefits to early extubation. It has been shown that earlier endotracheal tube removal hastens return of ciliary function and improves respiratory dynamics and coughing [11]. In fact, it has been proposed that early extubation should decrease the incidence of nosocomial pneumonias. Cheng and colleagues [12] have shown in a prospective randomized study that intrapulmonary shunt fraction improved significantly among patients extubated early. Moreover, mechanical ventilation itself can impair venous return and decrease cardiac output [13], thus prolonging SICU stay for adjustment of these parameters. Tachycardia and hypertension are other responses that can occur secondary to mechanical ventilation and increase SICU LOS by necessitating increased patient sedation. Furthermore, we have observed that patient and family satisfaction improve dramatically when patients are extubated early.

The concept of early extubation following CABG arose in the 1970s but did not gain widespread acceptance until recent years. Today’s economic climate has prompted universal interest in early extubation following open heart surgery. This strategy has been applied to both young and elderly patients, and cost savings have been demonstrated in younger, low-risk patient populations. Usage of short-acting anesthetic agents and lower doses of opioids has made this approach a feasible option when coupled with optimization in surgical technique and myocardial strategies.

That even earlier extubation (ie, at fewer than 4 hours) was successfully achieved in the majority of patients in this cohort supports the hypothesis that there should be no arbitrary time limit for postoperative extubation. In fact, we believe that there is no specific time impediment to extubation following CABG. In our institution, patients are extubated when they meet standard criteria: when they are awake, warm, not bleeding significantly, and hemodynamically stable, and when they have adequate oxygenation and ventilation. In fact, we have found that several significant preoperative medical problems do not necessarily impede any component of the fast-track recovery process [14].

Although conclusive evidence demonstrating the safety and efficacy of early extubation among CABG patients awaits prospective trials, we believe that early extubation is an integral part of the CABG fast-track recovery process. Adequate patient physiologic reserve together with optimized postoperative SICU care should be the factors that determine the proper timing of early extubation after CABG. However, because very few differences in clinical parameters exist between patients extubated in fewer than 4 hours compared with those extubated within 4 to 8 hours, efforts to further reduce extubation may be a worthwhile goal. This way, both the clinical and economic benefits of earlier extubation may be further optimized in cardiac surgery patients.


   References
Top
 Abstract
 Introduction
 Patients and methods
 Results
 Comment
 References
 

  1. Engelman R.M., Rousou J.A., Flack J.E., et al. Fast-track recovery of the coronary bypass patient. Ann Thorac Surg 1994;58:1742-1746.[Abstract]
  2. Arom K.V., Emery R.W., Petersen R.J., Schwartz M. Cost-effectiveness and predictors of early extubation. Ann Thorac Surg 1995;60:127-132.[Abstract/Free Full Text]
  3. Lee J.H., Kim K.H., van Heeckeren D.W., et al. Cost analysis of early extubation after coronary bypass surgery. Surgery 1996;120:611-619.[Medline]
  4. Higgins T.L. Early endotracheal extubation is preferable to late extubation in patients following coronary artery surgery. J Cardiothorac Vasc Anesth 1992;6:488-493.[Medline]
  5. Prakash O., Johnson B., Meij S., et al. Criteria for early extubation after intracardiac surgery in adults. Anesth Analg 1977;48:703-708.
  6. Lee J.H., Graber R., Popple C.G., et al. Safety and efficacy of early extubation of elderly coronary artery bypass surgery patients. J Cardiothorac Vasc Anesth 1998;12:381-384.[Medline]
  7. Lee J.H., Geha A.S. Postoperative care of the cardiovascular surgical patient. In: Baue A.E., Geha A.S., Hammond G., Laks H., Naunheim K., eds. Glenn’s thoracic and cardiovascular surgery, 6th ed. Stamford, CT: Appleton and Lange, 1996:1777-1791.
  8. Doering L.V., Imperial-Perez F., Monsein Esmailian F. Preoperative and postoperative predictors of early and delayed extubation after coronary artery bypass surgery. Am J Crit Care 1998;7:37-44.
  9. Habib R.H., Zacharias A., Engoren M. Determinants of prolonged mechanical ventilation after coronary artery bypass grafting. Ann Thorac Surg 1996;62:1164-1171.[Abstract/Free Full Text]
  10. Bando K., Sun K., Binford R.S., Sharp T.G. Determinants of longer duration of endotracheal intubation after adult cardiac operations. Ann Thorac Surg 1997;63:1026-1033.[Abstract/Free Full Text]
  11. Quasha A.L., Loeber N., Feeley T.W., Ullyot D.J., Roizen M.F. Postoperative respiratory care. Anesthesiology 1980;52:135-141.[Medline]
  12. Cheng D.C., Karski J., Peniston C., et al. Morbidity outcome in early versus conventional tracheal extubation after coronary artery bypass grafting. J Thorac Cardiovasc Surg 1996;112:755-764.[Abstract/Free Full Text]
  13. Gall S.A., Olsen C.O., Reves J.G., et al. Beneficial effects of endotracheal extubation on ventricular performance. J Thorac Cardiovasc Surg 1988;95:819-827.[Abstract]
  14. Konstantakos A.K., Lee J.H. Fast track recovery of the coronary bypass surgery patient. Curr Surg 1998;54:552-555.
Accepted for publication December 17, 1999.




This article has been cited by other articles:


Home page
 Ann. Thorac. Surg.Home page
D. L. Ngaage, S. Griffin, L. Guvendik, M. E. Cowen, and A. R.J. Cale
Changing Operative Characteristics of Patients Undergoing Operations for Coronary Artery Disease: Impact on Early Outcomes
Ann. Thorac. Surg., November 1, 2008; 86(5): 1424 - 1430.
[Abstract] [Full Text] [PDF]

Home page
 J Intensive Care MedHome page
S. S. Carson, C. E. Cox, G. M. Holmes, A. Howard, and T. S. Carey
The Changing Epidemiology of Mechanical Ventilation: A Population-Based Study
J Intensive Care Med, May 1, 2006; 21(3): 173 - 182.
[Abstract] [PDF]

Home page
 Ann. Thorac. Surg.Home page
U. Guller, K. J. Anstrom, W. L. Holman, R. M. Allman, M. Sansom, and E. D. Peterson
Outcomes of early extubation after bypass surgery in the elderly
Ann. Thorac. Surg., March 1, 2004; 77(3): 781 - 788.
[Abstract] [Full Text] [PDF]

Home page
 Eur. J. Cardiothorac. Surg.Home page
T. Bardell, J.F. Legare, K.J. Buth, G.M. Hirsch, and I.S. Ali
ICU readmission after cardiac surgery
Eur. J. Cardiothorac. Surg., March 1, 2003; 23(3): 354 - 359.
[Abstract] [Full Text] [PDF]

Home page
 Eur. J. Cardiothorac. Surg.Home page
J.F. Legare, G.M. Hirsch, K.J. Buth, C. MacDougall, and J.A. Sullivan
Preoperative prediction of prolonged mechanical ventilation following coronary artery bypass grafting
Eur. J. Cardiothorac. Surg., November 1, 2001; 20(5): 930 - 936.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Jai H. Lee
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Konstantakos, A. K.
Right arrow Articles by Lee, J. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Konstantakos, A. K.
Right arrow Articles by Lee, J. H.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ANN THORAC SURG ASIAN CARDIOVASC THORAC ANN EUR J CARDIOTHORAC SURG
J THORAC CARDIOVASC SURG ICVTS ALL CTSNet JOURNALS