Page 399 - ACCCN's Critical Care Nursing

Research vignette, Continued
blood pressure, heart rate, respiratory rate, Glasgow Coma Score, Certain limitations were apparent within the study. The recruit-
sedation, and Acute Physiology and Chronic Health Evaluation ment period of time for the study is unreported. It is not reported
(APACHE) III scores. There was no significant difference in gas whether random number generation was responsible for the cre-
exchange, respiratory rate, or haemodynamics. There was a signifi- ation of the randomisation sequence (n = 50) or whether this was
cant difference (P = 0.01) in tolerance, with nasal prongs being well undertaken by the recruiters. The researchers had identified their
tolerated. There was a trend (P= 0.09) toward better patient comfort study’s limitations. This could not be a double- or even single-
with HFNP. blind study as the patient participating and their nurse were aware
of which high-flow modality was being used. Further, it is
Conclusions 170
High-flow nasal prongs are as effective as HFFM in delivering thought, but remains unclear, what window of time with
oxygen to extubated patients who require high-flow oxygen. The one high-flow set up before change over to the alternative
tolerance of HFNP was significantly better than HFFM. strategy is a sufficient length of time to wash out one intervention
before measuring the clinical, self report and bedside observer
Critique patient data.
This article is a well-written and readable research study. It is also
the first to report a scientific comparison between these two often- There are a number of recognised factors that influence
employed oxygen-delivery modalities in clinical practice. The gas exchange such as skeletal muscle conditioning, haematologi-
article’s liberal use of tables and headings allows for ease of under- cal profile and diffusion capacity. Variability of these factors was
standing and the ability to locate specific information.
offset by the trial design as each participant was their own control
This clinical enquiry was a randomised controlled study. Each study in this study’s design. However, it was unclear whether patient
participant had a stabilisation period and following this, proceeded positioning was consistent within and between the study’s partici-
to be randomised to either protocol A or B. The stabilisation period pants. Patient positioning could influence the level of alertness,
became the control period for each participant and increased the airway clearance and gas exchange. It would need to be assumed
strength of the study design. The merit of this experimental design when interpreting these data that the temperature/humidity of the
is that extraneous variables are controlled for. Extraneous variables inspired gas with each intervention was consistent across the
may be antecedent or intervening. Examples of antecedent vari- sample. The function of airway mucosa and temperature of inspired
ables include age, gender, socioeconomic status and premorbid gas has been long established. 171
health status. These data provide a baseline to confirm similarity
between groups prior to assessment of an effect of the interven-
167
tion. Intervening variables may occur during the course of the The sample size was small (n = 44) and the risk of drawing conclu-
study and are unrelated to the clinical trial but may influence the sions based on a small sample size risks a Type II error. These results
dependent variables. For example a media report on the merit of support the researchers’ contention that a larger sample size is
clinical research may influence the public’s attitude to participation required. Power calculations to determine equivalence between
172
in a clinical trial. interventions exist. It is unclear how many bedside nursing staff
participated in this study and if any and/or regular staff in-service
The study was well conducted. The researchers were transparent education occurred to achieve inter-rater reliability of their reports
in their handling of data and reporting of all those initially recruited of the patients’ tolerance with these two high-flow modalities. Each
into this study via the CONSORT statement. The duration of ven- high-flow set up was trialled in 30-minute episodes. How fre-
168
tilation prior to extubation report wide confidence intervals. This quently the bedside nurse observed the patient’s tolerance of the
could suggest that a wide profile of patients were enrolled into this high-flow set up may have been variable. Interestingly the utility
study. Due to this trial being a prospective evaluation undertaken of nasal-delivered high flow oxygen therapy in generating a posi-
in the local setting it is possible to generalise the applicability of tive airway pressure has been examined and reported in healthy
findings across the population in Australia and New Zealand. subjects as proportional to rates of gas flow and reduced pressure
Outcome measures were a combination of quantifiable data such in mouth breathers in Australia and New Zealand in healthy sub-
173
as arterial blood gas analysis and vital signs in addition to subjec- jects and ICU patients albeit with small sample sizes. This study
174
tive measures i.e. the nurse’s report of the patient’s comfort and is important, as it is the first randomised trial that compares two
tolerance for the flow delivery system using the visual analogue popular high flow delivery systems and highlights that further gen-
scale (VAS). The VAS is a ubiquitous, valid and sensitive measure in eration of evidence is vital to support our clinical decision making
a range of age groups. 169 in everyday practice.

Learning activities
1. A patient has severe ARDS following aspiration pneumonia. 4. Describe and compare the differences between a simple, per-
Their FiO 2 is 1 and PaO 2 60 mmHg. Core temperature is 40°C sistent and reoccurring pneumothorax.
and the only medications are antibiotics. Any activity including 5. At the commencement of your shift you undertake a respira-
suctioning causes profound desaturation. What additional tory assessment of your patient. List the parameters that
measures could be implemented to minimise this effect? should be examined.
2. What is your understanding of ARDS?
3. List the interventions required for a nurse to safely care for a
patient with a provisional diagnosis of a novel infectious
disease.