Research Article
Early Extubation Protocol Following Valve and Coronary Artery Bypass Surgery
Williamson C1*, Fitton TP1, Smaroff GG1, Teague PD2, Shaff DA2, Curran JN3 and D’Agostino RS1
1Department of Thoracic and Cardiovascular Surgery, Lahey Hospital and Medical Center, Burlington, Massachusetts 01805, USA
2Department of Anesthesiology, Lahey Hospital and Medical Center, Burlington, Massachusetts 01805, USA
3Comparative Effectiveness Research Institute, Lahey Hospital and Medical Center, Burlington, Massachusetts 01805, USA
*Corresponding author: Williamson C, Lahey Hospital and Medical Center, 41 Mall Road, Burlington, Massachusetts 01805, UAS
Published: 24 Apr, 2017
Cite this article as: Williamson C, Fitton TP, Smaroff GG,
Teague PD, Shaff DA, Curran JN, et
al. Early Extubation Protocol Following
Valve and Coronary Artery Bypass
Surgery. Clin Surg. 2017; 2: 1424.
Abstract
Background: Early extubation protocols can be safely implemented in most patients undergoing
coronary artery bypass surgery. We have found that these results can be replicated in patients
undergoing valve surgery and combined coronary bypass and valve surgery as well.
Methods: We implemented an early extubation protocol on Apr 4th, 2011. Our goal was to extubate
all appropriately selected patients within 6 h after arrival to our ICU. We utilized the Society of
Thoracic Surgeons Adult Cardiac Surgical Database at our institution and compared our extubation
times from Jan 1st, 2008–Apr 3rd, 2011 to Apr 4th, 2011-Dec 31st, 2014. We used a chi square test
to compare how many patients were extubated within 6h, before and after implementation of this
quality improvement project. Fisher’s exact tests were used as well when sample sizes were small.
Results: Nearly seventy percent, 1295 of 1855 patients having cardiac surgery at Lahey Hospital and
Medical Center were extubated within 6h after implementing our rapid wean protocol. This was a
significant improvement compared to 29%, 455 of 1570 patients prior to our quality improvement
project (p<0.0001). These results were seen for coronary artery bypass as well as valve procedures
including combined aortic valve replacement and coronary bypass procedures.
Conclusion: An early extubation protocol can be safely implemented in patients undergoing valve
and combined valve and coronary artery bypass operations with similar success rates to those having
coronary artery bypass surgery alone.
Keywords: Extubation protocol; Coronary artery bypass surgery; Postoperative care; Quality care management
Introduction
Early extubation of coronary artery bypass (CABG) patients has been shown to reduce costs as well as intensive care unit and hospital lengths of stay [1-4]. It has been a focus of several studies to improve outcomes in the care of CABG patients. According to an analysis from the Society of Thoracic Surgeons Adult Cardiac Surgery Database (STS ACSD) there is a significant variation in post-operative ventilation times in CABG patients providing an opportunity for quality improvement across many institutions [5]. Most studies have focused on CABG patients and few include the impact of early extubation protocols on patients undergoing valve or combined valve and CABG procedures. Prolonged ventilation, defined in the STS ACSD as intubation longer than 24 h, is now one of five morbidity measures utilized in composite scores for evaluating performance of isolated CABG, isolated aortic valve replacement (AVR), AVR plus CABG, and mitral or mitral plus CABG procedures [6-9]. In this report we outline our early extubation protocol and have found that it can be effectively adopted for patients having valve and combined CABG and valve procedures as well as isolated CABG procedures.
Table 1
Table 2
Methods
This is a retrospective review of prospectively collected data from the Lahey Hospital and
Medical Center’s STS ACSD. Our Institutional Review Board approved this study, with waiver
of individual patient consent. We utilized the time intervals from Jan 1st, 2008–Apr 3rd, 2011 and
Apr 4th, 2011–Dec 31st, 2014 for comparison. Jan 1st, 2008 was when STS ACSD started tracking time to extubation data and Apr 4th, 2011 was when we initiated our
early extubation protocol. Patient characteristics and risk factors
are outlined in Table 1. There were no differences in the patient
populations during these two time periods with respect to mean
age, gender, and body surface area. There were more patients with
ejection fractions below or equal to 30% in the 2008 to 2011 preprotocol
cohort but low ejection fraction was not a contraindication
to initiating the rapid wean protocol. There was no difference in the
two patient populations with respect to mild or moderate chronic
obstructive pulmonary disease (COPD), but there were slightly more
patients with severe COPD in the earlier time period. Unless the
patient was on continuous pre-operative oxygen therapy at home
we did not consider severe COPD to contraindicate rapid wean. In
fact, we proactively tried to rapidly wean patients with COPD. Heart
failure within two weeks of surgery based on the New York Heart
Classification (NYHC) was not a contraindication to early extubation.
There were more patients in class IV heart failure within two weeks of
surgery in the early extubation group.
Exclusion criteria for early extubation included patients in
cardiogenic shock and patients who were in pulmonary edema and
required high flow supplemental oxygen or endotracheal intubation
preoperatively. Aortic dissections were excluded as well.
All patients were considered to be candidates for the protocol on
entry into the operating room with the exception of those meeting
the exclusion criteria listed above. The anesthesiologists decreased the
total dose of fentanyl, on induction, did not re-dose narcotics on rewarming,
and reversed the neuromuscular blockade at the completion
of the operation. The surgeon and anesthesiologist confirmed that
the patient was a candidate for the early extubation protocol at the completion of surgery. At this phase of care patients were excluded
if they met any of the exclusion criteria listed in Table 2.. If any of
these exclusion criteria were corrected in the Cardiothoracic Post
Anesthesia Care Unit (CTPACU) within the first few h of arrival, the
early extubation protocol was then activated. The early extubation
protocol is outlined in detail in the Appendix.
Propofol was used sparingly on transfer to the CTPACU
and discontinued immediately upon arrival. Postoperative pain
management strategy was changed to a low dose IV fentanyl
infusion on transfer that was discontinued prior to extubation. A
hydromorphone (Dilaudid) patient controlled analgesia (PCA) was
started once the patient was alert and capable of managing the digital
delivery devise. In elderly patients hydromorphone PCA was used
judiciously.
Chi square test was used to compare how many patients
were extubated both within 4 h and within 6 h, before and after
implementation of this quality improvement project. Fisher’s exact
tests were used as well when sample sizes were small.
Results
From Apr 2011 through Dec 2014, 1295 of 1855 (69.8%) patients
who had a CABG, valve repair or replacement, or a combination of
valve and CABG procedures were extubated within 6h of arriving to
the CTPACU. This was a significant improvement compared to 29%
(p <0001) that were extubated within 6h prior to instituting the rapid
wean protocol (Table 3). Nearly three quarters (74.6%) of patients
having CABG were extubated within 6h compared with 29.8%
(p<0.0001). We were equally successful in achieving our goal in 215
of 291(75.3%) patients having single valve procedures compared with 70 of 215 (32.6%) in the control period. These results were
achieved regardless of whether the patient had an AVR, mitral valve
replacement (MVR), or mitral valve repair.
Eighty four of 144 patients (58.3%) who had combined AVR and
CABG procedures were extubated within 6h compared with 32 of
126 (25.4%) before our quality improvement initiative (p<0.0001).
We did not see a statistically significant improvement in our early
extubation efforts in the combined MVR and CABG procedures.
Although the goal was to extubate patients within 6 h of arriving
in the CTPACU, many were extubated even earlier than our target
goal. Half of all patients undergoing CABG, 535 of 1064 (50.3%)
were extubated within 4h compared to 13.3%, 135 of 1,016 before
we initiated this quality improvement project (p<0.0001). We found
similar results with AVR, MV Repair, and CABG/AVR (Table 4).
Reintubation rates were similar before and after instituting our
rapid wean protocol, 4.3% and 3.8% respectively (p=0.46). Of the
1295 patients extubated after the protocol was started 36 of (2.8%)
were reintubated and none suffered any adverse events from having
to be re-intubated. The number of patients who remained intubated
over twenty-fourth decreased from 8.8% to 6.8% (p=0.02) after
initiation of our rapid wean protocol [10].
Table 3
Table 3
Number of patients extubated in 6 h or less. Jan 1st, 2008- Apr 3rd, 2011 before the early extubation/rapid wean protocol. Apr 4th, 2011-Dec 31st, 2014 after the protocol.
Table 4
Table 4
Number of patients’ extubated in 4 hours or less. Jan 1st, 2008–Apr 3rd, 2011 before the early extubation/rapid wean protocol. Apr 4th, 2011–Dec 31st, 2014 after the protocol.
Discussion
Early extubation following cardiac surgery is not a novel
concept. It was described as early as 1974 by Midell and colleagues
in 100 consecutive patients undergoing AVR, MVR, and combined
AVR and MVR. Ninety of their patients were able to be extubated
in the operating room or within two hours of arrival in the ICU,
challenging the standard practice of the time. Morphine was avoided
during induction or during the procedure and was used sparingly in
the postoperative period. Patients were awakened at the end of the
procedure, given what today would be considered a “spontaneous
breathing trial”, and extubated with satisfactory clinical assessment
and arterial blood gases. In the early days of cardiac surgery the
routine use of mechanical ventilation was considered a mainstay
in the treatment of respiratory failure following extracorporeal
circulation. As many of the causes of post perfusion respiratory
failure were eliminated, the need for prolonged ventilator support
also decreased. Yet it was still standard practice to sedate and ventilate
cardiac surgical patients overnight to minimize myocardial oxygen
demand and resulting ischemia [11].
In 1977, Prakash and colleagues demonstrated that 123 of
142 adult cardiac surgical patients were able to be extubated in the
operating room or within three h of admission to the recovery room [12]. This included patients who had isolated valve replacements and
coronary artery bypass procedures. Only five of the 123 patients were
re-intubated. They also utilized a spontaneous breathing trial and
established criteria for continued mechanical ventilation. If adequate
ventilation was maintained with a stable end title CO2 of less than
5.5% and other hemodynamic criteria were met their patients were
extubated. The most common indication for continued mechanical
ventilation was low mixed venous oxygen saturation and an elevated
left atrial pressure of greater than 20 torr.
A controlled randomized trial comparing early extubation within
2 h–4 h to late extubation 18 h–21 h following coronary artery
bypass surgery was published in the Anesthesia literature in 1980
[13]. This study demonstrated significantly less cardiopulmonary
morbidity in patients who were extubated early. Supporting early
extubation of patients following coronary artery bypass surgery was
the well described evidence of the pulmonary and cardiac physiologic
benefits on hemodynamics, and ventricular performance [14-16].
Another prospective, randomized, controlled trial by Cheng “et al.”
evaluated the outcomes and safety of early extubation after coronary
artery bypass grafting [4]. Modifying fentanyl dosing during surgery
enabled them to safely extubate 85% of their patients assigned to the
early extubation group. They demonstrated an improvement in postextubation
intrapulmonary shunt fraction and a reduction in ICU
and hospital length of stay in these patients.
Weaning the cardiac surgeon and the care team from the
obligatory overnight use of mechanical ventilation has taken more
time. The STS ACSD was utilized to study 274,231 patients who
underwent elective isolated CABG from 1,008 centers to assess
postoperative ventilation time in 2009 and 2010 [5]. In this multiinstitutional
study of uncomplicated patients who were ventilated
for less than 24 h, there was substantial variation in ventilator time
across centers. Ventilation times were 1.8 times higher in centers
above the 90th percentile compared to those below the 10th percentile
and that difference was not accounted for by patient characteristics
after adjusting for case mix. This study was published in 2013 and
was a clarion call for a quality improvement initiative to strive for the
shortest possible ventilation times for all patients.
The institution of an effective rapid wean program for cardiac
surgical patients is a multi-disciplinary team effort that includes
cardiac surgeons, anesthesiologists, physician assistants, intensive
care unit (ICU) nurses, and respiratory therapists. When we
evaluated our traditional weaning process we recognized that one
of the impediments to rapid weaning was the need for an individual
order for each step of the process. We eliminated that by establishing
a protocol with a single order set to initiate the Cardiothoracic Care
Unit Rapid Wean Protocol on arrival from the operating room.
We also recognized the importance of consistent application of
objective criteria for determining the readiness to wean and extubate
as outlined in Appendix 1. A Cochrane review and meta-analysis
of weaning protocols in critically ill patients has concluded that
weaning protocols decrease total duration of ventilation, weaning
duration, and length of stay in the intensive care unit [17]. However
these weaning protocols were not specific for cardiac surgery. A
standardized protocol for decreasing postoperative mechanical
ventilation for cardiac surgical patients is the framework that drives
the process. These criteria provide a framework for our care team to
proceed independently and proactively with weaning and extubation.
The intensive care nurses as well as the respiratory therapists become
the drivers of the process [18].
We recognize a major weakness of this manuscript lies in its
retrospective and non-randomized design. In addition we did
not attempt propensity matching of the patients. Our goal was
to implement a rapid wean protocol for all of our cardiac surgical
patients and measure how well we achieved that process as a quality
improvement initiative.
We did not measure outcome variables in our assessment of
this process improvement project but plan to do so. Other studies
have demonstrated improved clinical outcomes as well as improved
utilization of health care resources can result from early extubation
of cardiac surgical patients [1-4]. We embarked on this quality
improvement initiative and have demonstrated that a rapid wean
protocol can be safely implemented for patients undergoing coronary
artery bypass surgery, isolated valve surgery, and combined CABG
and AVR procedures. It requires a multidisciplinary team effort
with modification of the anesthetic management, adjustments in
post-operative pain management, and protocol driven weaning
parameters. Most importantly it requires a team effort to insure
effective implementation.
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