Discussion
Mechanical ventilation is a life supportive therapy for critically ill
patients with respiratory failure. Studies report that approximately
40% of adult patients admitted in an intensive care setting require
invasive mechanical ventilation. Two large seminal clinical trials
(Brochard 1994;Esteban 1995) indicated that the clinical processes
promoting timely recognition of a patient’s readiness to wean were more
important in reducing the duration of mechanical ventilation than the
weaning method itself.(2)Over the years, the weaning process has evolved
from being based on education and experience of the treating clinician
to a proper structured protocol-directed approach. This protocol-based
weaning is slowly gaining impetus in critical care units around the
globe because of its success in reducing the prolonged duration of
mechanical ventilation and hence, indirectly reducing the costs related
to health care. A number of factors influence the effectiveness of this
weaning protocol such as ICU organization, available resources, hospital
culture and healthcare professional characteristics. Therefore, the
designing of the weaning protocols should take into consideration the
social and cultural environment in which they are to be implemented to
accommodate the challenges in clinical practices in the concerned ICU
environment for a successful implementation. A study conducted by Rose
et al (11) revealed that the prevalence of implementation of weaning
protocol in European adult ICUs was 56% to 69%. However no such study
highlighting the impact of implementation of weaning protocols has been
reported from a resource limiting setting like ours. Hence we conducted
this study for assessment of current weaning practices and determine the
impact of implementation of protocol based weaning in a high burden
setting.
The weaning protocol was broadly divided into four major steps namely,
assessment of readiness to wean, pre-SBT trial, post-SBT trial and
extubation screen, which were included as quality indicators in our
study. There was a significant improvement with respect to compliance to
these steps of the weaning process as per protocol in the post
intervention phase. Most of the previous studies mentioned have not
assessed the compliance in following these steps of weaning protocol and
have assumed the compliance in following various steps of weaning to be
100%. However our study has tried to take a more realistic picture of
the scenario that would happen in an ICU in a high burden,
resource-limited setting wherein the compliance is affected by the
availability of resources.In our study, among the readiness criteria
only two, assessment of GCS and hemodynamic instability were being
followed in a large proportion of patients at baseline. However, in the
post intervention phase the compliance to these parameters remained high
while to other components increased. A similar improvement was seen in
the compliance to components of pre SBT and post SBT monitoring phase in
the post intervention phase as compared to pre intervention phase. Among
the secondary outcomes, although there was a trend towards reduction of
duration of mechanical ventilation in the second phase, the results did
not achieve statistical significance. There was an increase in the
proportion of patients who were successfully extubated, although the
results did not reach statistical significance. The frequency of
complications like re-intubation and VAP rates were lower in the post
intervention arm although the difference was not statistically
significant. This result was consistent with study conducted by Krishanet al in which no difference was found in number of patients
requiring reinstitution of mechanical ventilation, ICU length of stay
and hospital mortality in control and protocol weaning group.[9]
Elly et al conducted a study on neurosurgical patients showed
that implementation of weaning protocol based on traditional respiratory
physiologic parameters had practical limitations in postoperative
patients with no significant differences in complications, mortality and
duration of mechanical ventilation in control and intervention
group.[8] Simeone et al conducted a study on patients
undergoing cardiac surgery and reported lesser duration of mechanical
ventilation and length of ICU stay in the protocol weaning group as
compared to usual group.[12](Table 2)
This study is first of its kind, conducted in a high-burden,
resource-limited setting for evaluation of effect of implementation of
protocol-based weaning methods in a pragmatic scenario. The study
revealed low compliance to various parameters assessed as a part of
weaning process. Training of resident doctors was successful in
improving compliance with protocol-based weaning process.
There are a number of limitations in the study. This was short duration
study with small number of patients precluding any meaningful
conclusions on the effect on patient outcomes. A larger study population
could have shown a more significant change in the quality indicators of
patient outcomes, which were assessed. Even with a well-organized study,
there was less than 90% compliance with some parameters in the weaning
protocol. This means that there are many variables involved in the
process improvement. In this study, these barriers to protocol
compliance improvement, including the contributions of physician and
allied staff behaviour, were not measured. Identifying and rectifying
these variables could have led to a better rate of compliance with
weaning protocol in this study.