Indicators of Airway Secretion Weight in Mechanically Ventilated Subjects.

BACKGROUND: Clinicians may use adventitious breath sounds on lung auscultation and a "sawtooth" pattern on the ventilator expiratory flow waveform as indicators of the need for chest physiotherapy for airway-secretion clearance in mechanically ventilated patients. This study seeks to identify potential clinical and novel indicators of the weight of airway secretions cleared from a single session of chest physiotherapy in mechanically ventilated subjects. METHODS: We recorded airway crackles using artificial airway acoustic sound monitoring and computerized lung-sound amplitude using artificial airway acoustic sound detection and compared them to standard clinical assessments in 71 mechanically ventilated subjects immediately prior to a single session of chest physiotherapy. Correlational analyses were undertaken between the weight of airway secretions obtained after the single session of chest physiotherapy as the dependent variable and novel assessments, clinical assessments, patient characteristics, and ventilator parameters as the independent variables. Multiple linear regression analyses were then used to determine the best model to predict the weight of airway secretions obtained from the single chest physiotherapy session. Data are reported as mean and median as appropriate. Significance was set at P < .05. RESULTS: 71 mechanically ventilated subjects were included for analysis. Statistically significant associations with the weight of airway secretions included the presence of a sawtooth waveform on expiration and the novel assessment of average airway crackles during inspiration. The best predictive model of the weight of airway secretions included the presence of the sawtooth waveform on expiration and ventilator tidal volume. CONCLUSIONS: Simple clinical assessments used in this study were able to independently predict the weight of airway secretions cleared during a single session of chest physiotherapy. The novel assessments used in this investigation did not add any further value.

The effect of positive and negative message framing on short term continuous positive airway pressure compliance in patients with obstructive sleep apnea.

BACKGROUND: Continuous positive airway pressure (CPAP), the best available treatment for obstructive sleep apnea (OSA), requires long-term compliance to be effective. Behavioral interventions may be used to improve adherence to CPAP. We aimed to investigate whether positive or negative message framing impacts on CPAP compliance in patients with OSA, when compared to standard care. METHODS: Consenting patients with confirmed OSA were randomly allocated to receive along with their CPAP either positively or negatively framed messages (Pos; Neg), or standard care (Con). Standardized motivational messages were read out to patients during an initial teaching session and through weekly telephone calls. Patients' compliance data were reviewed 2 and 6 weeks following CPAP initiation. RESULTS: We randomized 112 patients to groups that were matched for age, BMI, and OSA severity. The positively framed group (Pos) showed greater CPAP usage after 2 weeks (total use 53.7±31.4 hours) as compared to the negatively framed and the control group (35.6±27.4 and 40.8±33.5 hours, P<0.05); however, no differences were seen at 6 weeks. There were more dropouts in the control group than in either framed groups (Pos n=5; Neg n=8; Con n=11; P<0.05). CONCLUSIONS: Positively framed messages can improve CPAP adherence in patients with OSA in the short-term; however, strategies for implementing its long-term use need to be developed.

Inter-Rater Agreement of Auscultation, Palpable Fremitus, and Ventilator Waveform Sawtooth Patterns Between Clinicians.

BACKGROUND: Clinicians often use numerous bedside assessments for secretion retention in participants who are receiving invasive mechanical ventilation. This study aimed to evaluate inter-rater agreement between clinicians when using standard clinical assessments of secretion retention and whether differences in clinician experience influenced inter-rater agreement. METHODS: Seventy-one mechanically ventilated participants were assessed by a research clinician and by one of 13 ICU clinicians. Each clinician conducted a standardized assessment of lung auscultation, palpation for chest-wall (rhonchal) fremitus, and ventilator inspiratory/expiratory flow-time waveforms for the sawtooth pattern. RESULTS: On the presence of breath sounds, agreement ranged from absolute to moderate in the upper zones and the lower zones, respectively. Kappa values for abnormal and adventitious lung sounds achieved moderate agreement in the upper zones, less than chance agreement to substantial agreement in the middle zones, and moderate agreement to almost perfect agreement in the lower zones. Moderate to almost perfect agreement was established for palpable fremitus in the upper zones, moderate to substantial agreement in the middle zones, and less than chance to moderate agreement in the lower zones. Inter-rater agreement on the presence of expiratory sawtooth pattern identification showed moderate agreement. The level of percentage agreement between the research and ICU clinicians for each respiratory assessment studied did not relate directly to level of clinical experience. CONCLUSIONS: Inter-rater agreement for all assessments showed variability between lung regions but maintained reasonable percentage agreement in mechanically ventilated participants. The level of percentage agreement achieved between clinicians did not directly relate to clinical experience for all respiratory assessments. Therefore, these respiratory assessments should not necessarily be viewed in isolation but interpreted within the context of a full clinical assessment.

Vibration response imaging: protocol for a systematic review.

BACKGROUND: The concept of lung sounds conveying information regarding lung physiology has been used extensively in clinical practice, particularly with physical auscultation using a stethoscope. Advances in computer technology have facilitated the construction of dynamic visual images derived from recorded lung sounds. Arguably, the most significant progress in this field was the development of the commercially available vibration response imaging (VRI) (Deep Breeze Ltd, Or-Akiva, Israel). This device provides a non-invasive, dynamic image of both lungs constructed from sounds detected from the lungs using surface sensors. In the literature, VRI has been utilized in a multitude of clinical and research settings. This systematic review aims to address three study questions relating to whether VRI can be used as an evaluative device, whether the images generated can be characterized, and which tools and measures have been used to assess these images. METHODS/DESIGN: This systematic review will involve implementing search strategies in five online journal databases in order to extract articles relating to the application of VRI. Appropriate articles will be identified against a set of pre-determined eligibility criteria and assessed for methodological quality using a standardized scale. Included articles will have data extracted by the reviewers using a standardized evidence table. A narrative synthesis based on a standardized framework will be conducted, clustering evidence into three main groups; one for each of the study questions. A meta-analysis will be conducted if two or more research articles meet pre-determined criteria that allow quantitative synthesis to take place. DISCUSSION: This systematic review aims to provide a complete overview of the scope of VRI in the clinical and research settings, as well as to discuss methods to interpret the data obtained from VRI. The systematic review intends to help clinicians to make informed decisions on the clinical applicability of the device, to allow researchers to identify further potential avenues of investigation, and to provide methods for the evaluation and interpretation of dynamic and static images. The publication and registration of this review with PROSPERO provides transparency and accountability, and facilitates the appraisal of the proposed systematic review against the original design. TRIAL REGISTRATION: PROSPERO registration number: CRD42013003751.