Volume 73, No.12: 2021 Siriraj Medical Journal
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Original Article
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Supanan Innok, M.N.S*, Witchuda Dokphueng, M.N.S*, Kamol Udol, M.D., M.Sc.**, Worawong Slisatkorn,
M.D.***, Prasert Sawasdiwipachai, M.D.****
*Department of Nursing, Siriraj Hospital, Bangkok 10700, ailand, **Department of Preventive and Social Medicine, ***Department of Surgery,
****Department of Anesthesiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, ailand
Clinical Outcomes and Cost of Ventilator Weaning
and Endotracheal Extubation Guided by An
Established Ventilator Weaning Protocol in Patients
Undergoing Elective Cardiac Surgery
ABSTRACT
Objective: To compare successful early extubation rates, complications, and cost before and aer the use of an
established ventilator weaning protocol in patients undergoing elective cardiac surgery.
Materials and Methods: Subjects were adult patients undergoing elective cardiac surgery who were clinically stable
within 2 hours aer surgery. e control group underwent conventional ventilator weaning at the discretion of their
attending sta. e intervention group underwent protocol-guided ventilator weaning. e primary outcome was
a successful early extubation (within 6 hours aer surgery). Secondary outcomes were complications from weaning
to 24 hours aer surgery, and the relevant cost related to respiratory and cardiovascular care within 24 hours aer
admission to the postoperative intensive care unit.
Results: e primary outcome occurred in 37 out of 65 patients (56.9%) in the intervention group and in 5 out of
65 patients (7.7%) in the control group (adjusted odds ratio 20.6; 95% condence interval 6.7–62.9, p<0.001). e
complication rates were not statistically dierent between the intervention and control groups (26.2% vs. 20.0%,
p=0.41). e relevant cost, approximated by the service charges, related to respiratory and cardiovascular care was
signicantly less in the intervention group than in the control group (median 2,491 vs. 2,711 ai baht, p<0.001).
Conclusion: e use of the established ventilator weaning protocol aer elective cardiac surgery was associated with
a higher rate of successful early extubation and lower cost related to respiratory and cardiovascular care compared
to the conventional practices of ventilator weaning and extubation. e rates of overall complications were not
signicantly dierent.
Keywords: Early extubation; cardiac surgery; ventilator weaning protocol; complication; cost (Siriraj Med J 2021;
73: 815-822)
Corresponding author: Kamol Udol
E-mail: kamol.udo@mahidol.ac.th
Received 18 May 2021 Revised 17 October 2021 Accepted 27 October 2021
ORCID ID: https://orcid.org/0000-0002-1508-7749
http://dx.doi.org/10.33192/Smj.2021.106
INTRODUCTION
Open-heart surgery remains an important treatment
option for patients with coronary artery disease, valvular
heart disease, and congenital heart disease. Aer successful
open-heart surgery, patients oen require further ventilatory
support for a period of time until the eects of general
anesthesia fade and their vital signs are stable. Timely
ventilator weaning and endotracheal extubation is essential
in order to avoid unnecessary prolonged ventilation and,
at the same time, to minimize the adverse eects of too
early weaning and extubation.
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At Siriraj Hospital, the process of ventilator weaning
in elective cardiac surgery patients in the postoperative
intensive care unit (ICU) has conventionally been handled
primarily by the attending nurse, under the supervision
of the attending ICU physician, without any specic
guidance. e nurse initiates the process of ventilator
weaning and regularly monitors the patient’s response
and weaning parameters. When the patient is considered
ready for extubation, the nurse noties the attending
ICU physician to conrm the evaluation and to perform
the extubation. e ventilator weaning process depends
considerably on the individual nurse’s experience and
preference. is leads to a variation in practice and can
result in an unnecessarily prolonged intubation in some
patients, especially those who are ready for extubation
during the night. Prolonged ventilatory support and
delayed endotracheal extubation are associated with an
increase in the length of ICU and hospital stay, adverse
clinical outcomes, including an increase in mortality, and
higher health care costs.
1,2
Previous studies found that
post cardiac surgery patients with stable hemodynamics
could be safely extubated within 4–6 hours aer surgery.
3,4
In order to reduce variations in practice and to avoid
delayed extubation, a team comprising postoperative
ICU nurses, a cardiovascular-thoracic surgeon, and a
cardiovascular anesthesiologist was formed to establish
a protocol for ventilator weaning and extubation for
postoperative cardiac surgery patients. e protocol
species the steps and activities to be followed by the
attending nurse, with an aim for early extubation within
6 hours aer surgery.
We conducted this study to evaluate the eects
of using the established ventilator weaning protocol in
patients undergoing elective cardiac surgery compared
to conventional weaning practices.
MATERIALS AND METHODS
is prospective pre-post intervention study was
conducted at Siriraj Hospital in Bangkok, ailand. e
Institutional Review Board of the Faculty of Medicine
Siriraj Hospital approved the study protocol. All the
subjects provided written informed consent to participate
in the study.
Study participants
Patients were potentially eligible if they had coronary
artery disease, valvular heart disease, or adult congenital
heart disease that required elective cardiac surgery for
the rst time, were aged 18–75 years old, and had a le
ventricular ejection fraction (LVEF) of ≥ 45%, and an
echocardiographically estimated right ventricular systolic
pressure (RVSP) of ≤ 60 mmHg. After the surgery,
patients were admitted to the postoperative ICU. At 2
hours aer surgery, the patients were assessed for their
nal eligibility. Patients were excluded if they met at
least one of the following exclusion criteria at 2 hours
aer surgery: a Richmond Agitation and Sedation Scale
(RASS) of < –2; pulse oximetry oxygen saturation (SpO
2
)
of < 95%; serious cardiac arrhythmia [symptomatic
bradycardia with a heart rate of < 50 beats per minute
(BPM), second- or third-degree atrioventricular block,
atrial brillation with a ventricular rate of > 120 BPM,
atrial utter, supraventricular tachycardia, sustained
ventricular tachycardia, ventricular fibrillation, or
pulseless electrical activity]; unstable hemodynamics
[sustained hypotension (mean arterial pressure (MAP)
of < 65 mmHg or systolic blood pressure (SBP) of < 90
mmHg) for longer than 10 minutes, at least 2 episodes
of hypotension (MAP of < 65 mmHg or SBP of < 90
mmHg) within the previous 2 hours, receiving at least 5
microgram/kg/min of dopamine or dobutamine, or at least
0.1 microgram/kg/min of adrenaline or norepinephrine,
requiring mechanical circulatory support (intra-aortic
balloon pump, ventricular assist device, or extra-corporeal
membrane oxygenation), or had a urine output of < 1
mL/kg/hour]; chest drain content of > 100 mL/hour for
2 consecutive hours; and the occurrence of new stroke.
Patients with a documented diculty in intubation were
also excluded.
Study procedures
Patients enrolled before implementation of the
established ventilator weaning protocol (i.e., the conventional
weaning group) were managed conventionally regarding
ventilator weaning and extubation by the attending nurse
in consultation with the attending ICU physician in the
postoperative ICU. Patients were put on mechanical
ventilation upon ICU admission, usually in the assist/
control mode. e weaning process started with a gradual
reduction of the fraction of inspired oxygen (FiO
2
) to
0.4-0.5 while maintaining the SpO
2
at 95% or higher.
When this level of FiO
2
was achieved and the patient was
clinically stable and conscious, the ventilator mode was
then switched to synchronized intermittent mandatory
ventilation (SIMV) with pressure support (PS). When
the attending sta were condent that the patient could
tolerate this ventilator mode well and was clinically stable,
the patient was put on spontaneous ventilation with either
T-piece or continuous positive airway pressure (CPAP) with
PS. When the patient’s respiratory and clinical conditions
were ready, the attending ICU physician performed the
extubation. e specic details and timing of each step
Innok et al.
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were not specied and were le to the discretion of the
attending nurse in consultation with the attending ICU
physician. During the process, the patient’s conditions
were regularly monitored and management was provided
accordingly.
e established ventilator weaning protocol was
implemented in April 2016, and patients enrolled in
the study thereaer comprised the protocol weaning
group. e protocol provides details of and timing for
the activities at each step, together with the criteria for
the assessment of patients during the weaning process.
e protocol aims for extubation to be performed within
6 hours aer surgery if the patients are stable and do not
have major complications. e protocol is summarized
in Fig 1.
Outcomes
e primary outcome was a successful extubation
within 6 hours aer the surgery. Extubation was considered
successful if there were no respiratory, cardiovascular, or
neurological complications until 24 hours aer surgery,
and no re-intubation within 48 hours aer extubation.
Secondary outcomes were complications recorded from
the beginning of ventilator weaning to 24 hours aer
surgery, and the relevant cost related to respiratory and
cardiovascular care within 24 hours aer admission to
the ICU. Respiratory complications included new or
worsening atelectasis, pneumothorax, re-intubation
within 48 hours aer extubation, and moderate or severe
acidosis or alkalosis. Cardiovascular complications included
postoperative myocardial infarction, signicant arrhythmias
(atrial utter, atrial brillation with rapid ventricular
rate, supraventricular tachycardia, sustained ventricular
tachycardia, ventricular brillation, pulseless electrical
activities), and hypotension (MAP < 65 mmHg or SBP
< 90 mmHg for longer than 10 minutes). Neurological
complication was reected by a Glasgow coma scale of
< 13. e cost considered in this study was limited to
that related to inotropic agents, antiarrhythmic agents,
procedures related to respiratory care (endotracheal
intubation, ventilator use, suction, chest x-ray, arterial blood
gas analyses, and intercostal drainage), and cardiovascular
care (intraarterial blood pressure monitoring, use of
infusion pumps, electrocardiography, analyses of cardiac
biomarkers, and electrical cardioversion). For each service
item, we used the service charge determined by Siriraj
Hospital as a proxy for its cost. e service charge for
each service item was xed throughout the study period.
Statistical analyses
On the basis of our local ICU statistics, the rate of
successful extubation within 6 hours aer cardiac surgery
was approximately 25%. To demonstrate a doubling
of the successful extubation rate aer the use of the
established ventilator weaning protocol with the power
of 80% at a two-sided signicance level of 0.05 and the
assumption of a 10% loss of subjects, it was determined
that a sample size of 65 subjects in each group would be
required.
e patients’ characteristics were summarized with
the median and interquartile range (IQR), or number
and percentage, and were compared between groups
using the Mann–Whitney U test, chi-square test, or the
Fisher’s exact test as appropriate. e primary outcome
was analyzed using multiple logistic regression analysis,
adjusted for imbalances in the baseline characteristics
(characteristics with a p-value of < 0.2 in comparisons
between groups). e magnitude of the eect is presented
as an adjusted odds ratio (OR) and its 95% condence
interval (CI). e complication rates were compared
between groups using the chi-square test. e cost was
compared using the Mann–Whitney U test.
RESULTS
In total, 130 patients participated in the study: 65 in
the conventional weaning group and 65 in the protocol
weaning group. All the patients completed the study
protocol and were included in the analyses. e median
age was 61.5 years old and 61.5% were male. Comorbidities
were prevalent; almost 40% of the study participants had
diabetes, about three-quarters had hypertension, and
slightly more than half had dyslipidemia. Coronary artery
bypass gra (CABG) surgery was performed, as a single
procedure or combined with other procedures, in 74%
of the subjects. Valve surgery, alone or combined with
other procedures, was done in 32% of the subjects. e
patients’ baseline characteristics were not statistically
signicantly dierent between the groups (Table 1).
Primary outcome
e median (IQR) duration of intubation was 5.8
(5.3–6.0) hours in the protocol weaning group and 9.0
(7.4–11.1) hours in the conventional weaning group (p <
0.001). e primary outcome (successful extubation within
6 hours aer surgery) occurred in 37 patients (56.9%) in
the protocol weaning group and in 5 patients (7.7%) in
the conventional weaning group (Table 2). e OR for
the primary outcome, adjusted for sex, the presence of
diabetes mellitus, and the presence of coronary artery
disease, was 20.6 (95% CI 6.7–62.9, p < 0.001) for the
intervention group compared to the control group.
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Innok et al.
No
No Yes
Step 4
Post-extubation care
Extubation
Step 3
Perform
extubation
5
th
–6
th
hour
Final assessment
- Spontaneous breathing above the ventilator rate, RR 10–30/min
- Spontaneous TV 5–7 ml/kg, Minute ventilation 5–10 L/min
- SpO
2
≥ 95%
-
RSBI (f/V
T
) ≤ 105
Step 2
Prepare for
extubation
3
rd
–4
th
hour
Initial assessment
- Breathing spontaneously above the ventilator rate, RR 10–30/min
- Spontaneous TV 5–7 ml/kg, Minute ventilation 5–10 L/min
- ABG: pH 7.35–7.45, PaO
2
≥ 90 mmHg, PaCO
2
35–45 mmHg, HCO
3
22–26 mEq/L
- PaO
2
/FiO
2
> 200
- SpO
2
≥ 95%
RR 2 breaths q 15–30 minutes until achieving RR 4–6/min
Pre-extubation
- Upright position
- Clear airway and rest the patient for 30 minutes
- Ask the patient to take deep breaths
O
2
T-Piece 7–10 L/min
After 30 minutes: ABG for evaluation of gas exchange
CPAP + PS 5–8 cmH
2
O
After 30 minutes: ABG for evaluation of gas exchange
Assessment for extubation readiness
- Good consciousness: Alert and cooperative
- Adequate gas exchange: pH 7.35–7.45, PaO
2
≥ 90 mmHg, PaCO
2
35–45 mmHg, HCO
3
22–2 6 mEq/L, SpO
2
≥ 95 %, RR ≤ 24 /min
- Stable hemodynamics: MAP ≥ 65 mmHg, SBP ≥ 90 mmHg, Dobutamine or Dopamine < 5 µg/kg/min, Adrenaline or Norepinephrine < 0.1 µg/kg/min
- No bleeding: Chest tube output < 50 ml/hr
- No significant arrhythmia: Symptomatic bradycardia, A-V Block, AF, Atrial flutter, SVT, Sustained VT, VF, PEA
- No increased work of breathing: No rapid shallow breathing pattern, No paradoxical abdominal movement
- Adequate Pain control: Pain score < 3
- No anxiety
- Rest the patient
- Maintain ventilator setting
- Reassess within 1 hour
(total duration of this stage
3 hours)
- *If necessary, repeat ABG
If PaO
2
≤ 60 mmHg, SpO
2
< 90%
- CXR, ABG
- Consider re-intubation
- PaO
2
≥ 90 mmHg, SpO
2
≥ 95%
- Ability to maintain RR 10–30/min
- Ability to cough and clear secretions
- Deep breathing exercise
Figure 1. Ventilator weaning and extubation protocol after elective cardiac surgery
Step 1
Initiation of
ventilator weaning
1
st
–2
nd
hour
Evaluate physiologic criteria
- Awake: Eye opening, moving spontaneously and following command
- Adequate gas exchange: SpO
2
≥ 95%
- No new onset arrhythmia or serious dysrhythmia: Symptomatic bradycardia, A-V Block, AF, Atrial flutter, SVT, Sustained VT, VF, PEA
- Stable hemodynamics: MAP ≥ 65 mmHg, SBP ≥ 90 mmHg, urine > 1 ml/kg/hr, Dobutamine or Dopamine < 5 µg/kg/min, Adrenaline or
Norepinephrine < 0.1 µg/kg/min, No IABP, No VAD, No ECMO
- No need of reoperation: Chest tube output < 100 ml/hr
- No new stroke
- No difficult intubation
Ventilator setting by anesthesiologist
CMV rate 10–12/min
Verify baseline ABG within 20 minutes
Assessment of airway and cardiac conditions
Titrate FiO
2
to 0.4–0.5
maintain SpO
2
≥ 95%
*Clear airway and confirm CXR if necessary
Wean Ventilator Settings
- SIMV + PS 5–8 cmH
2
O, Limit PEEP ≤ 5 cmH
2
O
- After 30 minutes, ABG for evaluation of gas exchange
- Assess vital signs q 30 minutes
No
- Maintain previous setting
- Minimal sedation just for
comfort
- Upright and comfortable
position
Reassessment until
appropriate conditions are met
Post cardiac surgery
Admission to Postoperative ICU
All criteria met
Weaning as clinically
indicated
Notify Physician
Fig 1. Ventilator weaning and extubation protocol aer elective cardiac surgery
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TABLE 1. Characteristics of the study participants at enrolment.
Characteristic Total Protocol Conventional p-value
a
(n = 130) weaning weaning
(n = 65) (n = 65)
Age (year) – median (IQR) 61.5 60.0 62.0 0.537
b
(54.0–6 7.0) (52.5–67.0) (55.0–67.0)
Male – no. (%) 80 (61.5) 45 (69.2) 35 (53.8) 0.071
Comorbidities – no. (%)
Diabetes mellitus 48 (36.9) 20 (30.8) 28 (43.1) 0.146
Hypertension 99 (76.2) 52 (80.0) 47 (72.3) 0.303
Dyslipidemia 70 (53.8) 36 (55.4) 34 (52.3) 0.725
Chronic kidney disease 8 (6.2) 2 (3.1) 6 (9.2) 0.273
c
COPD/Asthma 5 (3.8) 1 (1.5) 4 (6.2) 0.365
c
eGFR
d
(mL/min/1.73 m
2
) – median (IQR) 75.4 75.8 75.1 0.524
b
(62.6–91.8) (65.2–91.6) (60.8–91.8)
Smoking status – no. (%) 0.639
Current smoker 11 (8.5) 7 (10.8) 4 (6.2)
Ex-smoker 31 (23.8) 15 (23.1) 16 (24.6)
Non-smoker 88 (67.7) 43 (66.2) 45 (69.2)
ASA class – no. (%) 1.000
c
2 5 (3.8) 2 (3.1) 3 (4.6)
3–4 124 (96.2) 63 (95.4) 62 (93.8)
Cardiac condition
e
– no. (%)
Coronary artery disease 96 (73.8) 52 (80.0) 43 (66.2) 0.075
Valvular heart disease 43 (33.1) 19 (29.2) 24 (36.9) 0.351
Congenital heart disease 8 (6.2) 4 (6.2) 5 (7.7) 0.730
c
Type of surgery – no. (%) 0.367
c
Single procedure
CABG surgery 83 (63.8) 44 (67.7) 39 (60.0)
Valve surgery 25 (19.2) 8 (12.3) 17 (26.2)
Closure of septal defect 4 (3.1) 2 (3.1) 2 (3.1)
Combined procedures
CABG and valve surgery 13 (10.0) 8 (12.3) 5 (7.7)
Valve surgery and closure of septal defect 4 (3.1) 2 (3.1) 2 (3.1)
Other 1(0.8) 1 (1.5) 0 (0.0)
Operation time (minutes) – median (IQR) 155 150 170 0.257
b
(120–216) (120–199) (120–235)
a
Conventional weaning vs. Protocol weaning, Chi-square test unless indicated otherwise.
b
Mann–Whitney U test.
c
Fisher’s exact test.
d
Calculated using the CKD–EPI creatinine equation.
e
Listed conditions are not mutually exclusive.
IQR: Interquartile range, COPD: Chronic obstructive pulmonary disease, eGFR: Estimated glomerular ltration rate, CABG: Coronary
artery bypass gra, ASA: American Society of Anesthesiologists.
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Secondary outcomes
Overall, 30 subjects suered at least 1 complication
from the beginning of ventilator weaning to 24 hours
aer the surgery: 17 (26.2%) in the protocol weaning
group and 13 (20.0%) in the conventional weaning group
(p = 0.405) (Table 3). Atrial brillation developed more
frequently in the protocol weaning group than in the
conventional weaning group (8 vs. 3 subjects respectively).
Two subjects in the protocol weaning group required
inotropic agents. In both groups, no subject required
re-intubation within 48 hours.
The service charges related to respiratory and
cardiovascular care within 24 hours aer admission to
the ICU were signicantly less in the protocol weaning
group than in the conventional weaning group [median
(IQR) 2,491 (2,308–2,652) ai baht (THB) vs. 2,711
(2,479–2,945) THB, p < 0.001] (Table 3).
TABLE 2. Primary outcome.
TABLE 3. Secondary outcomes.
Protocol Conventional Adjusted OR
a
p-value
weaning weaning (95% CI)
(n = 65) (n = 65)
Successful extubation within 6 hours 37 (56.9) 5 (7.7) 20.6 < 0.001
after surgery – no. (%) (6.7–62.9)
a
Adjusted for sex, presence of diabetes mellitus, presence of coronary artery disease.
OR: odds ratio, CI: condence interval.
Protocol Conventional p-value
weaning weaning
(n = 65) (n = 65)
Complications
a
– no. (%) 17 (26.2) 13 (20.0) 0.405
Respiratory – no. (%)
Atelectasis 4 (6.2) 4 (6.2)
Pneumothorax 1 (1.5) 1 (1.5)
Acidosis (arterial pH < 7.25) or alkalosis (arterial pH > 7.5) 1 (1.5) 1 (1.5)
Cardiovascular – no. (%)
Atrial brillation 8 (12.3) 3 (4.6)
Supraventricular tachycardia 1 (1.5) 0 (0.0)
Hypotension 3 (4.6) 2 (3.1)
Requirement of inotropic agents 2 (3.1) 0 (0.0)
New pathological Q wave or new LBBB in ECG – no./total (%) 1/52 (1.9) 3/44 (6.8)
Costs
b
(THB) – median (IQR) 2,491 2,711 < 0.001
(2,308–2,652) (2,479–2,945)
a
Complications recorded from the beginning of ventilator weaning to 24 hours aer surgery.
b
Approximated by the service charges related to respiratory and cardiovascular care within 24 hours aer admission to the postoperative
intensive care unit.
LBBB: le bundle branch block, ECG: electrocardiography, THB: ai baht, IQR: Interquartile range.
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DISCUSSION
In this prospective pre-post intervention study
among patients undergoing elective cardiac surgery, the
implementation of the established ventilator weaning
protocol led to a remarkable increase in the rate of
successful extubation within 6 hours aer surgery and
a decrease in service charges related to respiratory and
cardiovascular care within 24 hours aer admission to the
postoperative ICU, when compared to the conventional
weaning practices. ere was no statistically signicant
increase in the rates of respiratory and cardiovascular
complications.
Early extubation in stable postoperative cardiac
patients, when compared to late extubation, was shown in
previous studies to shorten the length of ICU and hospital
stay, and to reduce healthcare costs.
3,5-9
Strategies that
enhance early extubation would, therefore, be benecial
for both patients and the healthcare system. A number
of studies have found that ventilator weaning guided
by an established weaning protocol shortens the time
to extubation and increases the rate of early extubation
when compared to weaning without a guide among
cardiac patients in a coronary care unit or post cardiac
surgery patients.
10-12
Moreover, early extubation in cardiac
surgery patients was found to lead to a reduction in costs
and an improvement in health resource utilization.
5,9
e results of our study conrm the clinical and cost
benets of protocol-guided ventilator weaning in post
cardiac surgery patients.
Implementing the established ventilator weaning
protocol appeared to be safe. In this study, no patients
required re-intubation within 48 hours aer extubation.
e rates of respiratory and cardiovascular complications
were similar between the 2 groups, except for atrial
brillation, which was higher in the protocol weaning
group. Previous studies did not observe an increased rate
of atrial brillation in patients with early extubation. It is
still not clear whether this increase in atrial brillation in
our study was true or just a chance nding. Additional
information is required before a denite conclusion
regarding this issue can be made.
e established ventilator weaning protocol clearly
species the steps to take and time frames to follow during
the weaning process; thereby reducing the variations in
practice, hastening the process of weaning, and enhancing
the success rate of early extubation. In addition, the
protocol also provides monitoring criteria to determine the
progression of the patients and the actions to be taken if
the patients do not progress as expected. In conventional
weaning practices, extubation in some patients who are
ready during the night may be delayed until the next
morning due to concerns about safety, as the number of
sta during the night may be less than that during the day.
Moreover, it might be perceived that night sta may not
be as vigilant as day sta in detecting complications aer
extubation. Our study provides assurances that following
the established weaning protocol does not increase the
risk of complications aer extubation, regardless of the
time of extubation.
Experts have suggested that a ventilator weaning
protocol should be developed using a multidisciplinary team
approach.
13
e ventilator weaning protocol implemented
in this study was developed by a team of postoperative
ICU nurses, a cardiovascular-thoracic surgeon, and a
cardiovascular anesthesiologist. In our institution, and
in this study, the attending nurse plays a primary role in
the process of ventilator weaning, in consultation with
the attending ICU physician when necessary. Nurses have
important roles to play in various strategies essential for
successful ventilator weaning, including enhancing the
readiness to wean, frequent assessment of the readiness
to wean, encouraging spontaneous breathing during
weaning, and the use of spontaneous breathing trials.
14
Other studies support the success of ventilator weaning
and early extubation when directed by a nurse using a
pre-specied protocol.
12,15
Employing the result of our study to clinical practice
has potential implications for post cardiac surgery
patients and for health care system. For patients, early
ventilator weaning and endotracheal extubation is
likely to reduce discomfort and anxiety associated with
mechanical ventilation and the endotracheal tube. e
length of postoperative ICU stay is likely to be shortened.
Mechanical ventilators and ICU beds could therefore be
utilized more eciently as they become more readily
available to other patients in need. In ailand, about
11,000 adults underwent CABG and/or valve surgery
in 2019.
16
Applying the protocol-guided early ventilator
weaning and extubation could lead to millions of ai
baht being saved each year.
However, our study had some limitations to note.
Group allocations for each subject did not follow a process
of randomization. us, selection bias and some eects
of unmeasured or unknown confounding factors could
not be entirely excluded. e successful extubation rate
within 6 hours aer surgery in the conventional weaning
group (7.7%) was much lower than that estimated in our
sample size calculation (25%). is would indicate bias
in the study and may have led to an overestimation of
the eect of protocol weaning compared to conventional
weaning. e unadjusted OR estimated from the result
of the study was 15.9 (95% CI 5.6–44.7, p < 0.001).
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However, if we assume an approximate 25% successful
extubation rate in the conventional weaning group (16
subjects out of 65), the result would still be statistically
signicant in favor of protocol weaning, but the eect
would be less pronounced, with an unadjusted OR of
4.0 (95% CI 1.9–8.6, p < 0.001). Also, we used relevant
service charges related to respiratory and cardiovascular
care in each group as proxies for the cost data. However,
for any particular service in our institution, cost is a
primary determinant of its service charge. erefore, a
comparison of service charges would provide a similar
conclusion as the comparison of costs between groups.
Last but not least, this study was conducted in a single
university hospital in patients with elective cardiac surgery;
the results may not be applicable to other care settings
or to other groups of patients.
CONCLUSION
In conclusion, ventilator weaning and extubation
guided by an established weaning protocol in patients
undergoing elective cardiac surgery was found to be
associated with a higher rate of successful extubation
within 6 hours aer surgery and lower cost related to
respiratory and cardiovascular care within 24 hours
aer admission to the postoperative ICU, compared
to conventional practices of ventilator weaning and
extubation. e rates of overall complications from the
initiation of ventilator weaning to 24 hours aer surgery
were not signicantly dierent.
ACKNOWLEDGEMENT
is study was supported by a grant from the Siriraj
Research Development Fund (managed by the Routine to
Research Project), Faculty of Medicine Siriraj Hospital,
Mahidol University.
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