A dissertation submitted to the Faculty of Health Sciences, University of Witwatersrand,
Johannesburg, in fulfilment of requirements for the degree of Masters of Science.
Johannesburg 2012 / Background:
The detrimental effects of prolonged mechanical ventilation (MV) on the respiratory muscles,
especially the diaphragm, are well documented and it is crucial that MV should be discontinued as
soon as possible to prevent added complications and additional risks to patients with critical
illness. The spontaneous breathing stage of MV can be managed as a rehabilitation and
conditioning phase for the respiratory muscles due to the fact that the respiratory muscles are
more active during this stage of MV. Weaning strategies that provide insufficient respiratory work,
too high a respiratory muscle load or insufficient respiratory muscle rest may lead to respiratory
muscle fatigue and consequently failed weaning and extubation. The aim of this research project
was to develop an individualised continuous positive airway pressure (CPAP) weaning
programme and test its effects on the outcomes of extubation in the adult ventilated patient.
Method:
An experimental, prospective, non-randomised, sequential study of two groups of subjects was
performed. Forty eight subjects [group one: n =24 (control) and group two: n = 24 (intervention)],
who were mechanically ventilated for longer than 48 hours, in an open adult, general intensive
care unit were recruited. Subjects in the control group were weaned according to the standard
weaning programme of the test setting at the time; and those in the intervention group were
weaned according to an individualised CPAP programme. This weaning programme was
developed utilising three principles of muscle rehabilitation namely; daily stepwise progression,
sufficient rest and recovery periods and adapted to the individual needs and progression of each
subject. Objective measurements such as the rapid shallow breathing index (RSBI), RSBI rate
and the maximum inspiratory pressure (MIP) were used to determine the subjects in group two’s
readiness for a spontaneous breathing trial. The primary outcomes assessed were time spent in
the different stages of MV, rate of failure to sustain spontaneous breathing in stage 3 of MV,
successful extubation and mortality rate.
Results and Discussion:
The difference in rate of failure to sustain spontaneous breathing between the two groups was
statistically significant (p = 0.01) with 10 events of failure in group one and three in group two. The
rate of successful extubation from MV between groups one and two was 70.8% and 91.7%
iv
respectively (p=0.52). The mortality rate was 33.3% for group one and 8.3% for group two (p =
0.02).
The difference in the total time spent on MV (days) did not differ significantly (group one = 8.6 (±
0.40) days; group two = 9.3 (±0.32) days; p = 0.75).
The results yielded from this study suggest that the use of a multidisciplinary team model and an
individualised CPAP programme aids successful extubation from MV as the success rate was
much higher in the intervention group than in the control group without adding additional time on
MV.
Conclusion:
Results from this study showed that the implementation of an individualised CPAP programme
during the spontaneous breathing stage of MV may improve the outcomes of extubation in adult
ventilated patients.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/13671 |
| Date | January 2012 |
| Creators | Erasmus, Wilma A |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf, application/pdf |
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