Respiratory Care

To determine the magnitude, duration, and consistency of the effects of lung recruitment maneuvers (RMs) on oxygenation, lung mechanics, and comfort in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).

We conducted a prospective physiologic study at 3 tertiary-care hospitals. We enrolled 28 consecutive eligible patients with ARDS or ALI and a ratio of P_aO2 to fraction of inspired oxygen (P_aO2 /F_IO2 ) ≤ 250 mm Hg while receiving F_IO2 ≥ 0.50. We performed RMs twice daily for 3 days. The first RM was at 35 cm H₂O for 20 s. If initial response was equivocal, the clinician immediately administered another RM at a higher pressure (40 cm H₂O, then 45 cm H₂O) or for longer period (30 s, then 40 s), in a randomized order. Each patient had up to 6 sets of up to 3 RMs.

Twenty-seven patients met the criteria for ARDS at baseline; 1 had ALI. There was no net effect on oxygenation or pulmonary mechanics following the first or subsequent RMs. The largest rise in P_aO2 was from 61 mm Hg to 71 mm Hg, and the largest decrease was 6 mm Hg following the first RM. Augmenting the inflation pressure or duration had no significant effect. These findings precluded analyses about predictors of response or consistency of response. Over the entire study of 122 RMs, 5 patients developed ventilator asynchrony, 3 appeared uncomfortable, 2 experienced transient hypotension, and 4 developed barotrauma that required intervention.

These results do not support the addition of scheduled RMs to usual treatment for ALI or ARDS.

Small endotracheal tubes (ETTs) and neonatal ventilators can impact gas exchange, work of breathing, and lung-mechanics measurements in infants, by increasing the expiratory resistance (R_E) to gas flow.

We tested two each of the Babylog 8000plus, Avea, Carestation, and Servo-i ventilators. In the first phase of the study we evaluated (1) the imposed R_E of an ETT and ventilator system during simulated passive breathing at various tidal volume (V_T), positive end-expiratory pressure (PEEP), and frequency settings, and (2) the intrinsic PEEP at various ventilator settings. In the second phase of this study we evaluated the imposed expiratory work of breathing (WOB) of the ETT and ventilator system at various PEEP levels during simulated spontaneous breathing using an infant lung model. Pressure and flow were measured continuously, and we calculated the imposed R_E of the ETT and each ventilator, and the intrinsic PEEP with various PEEP, V_T, and frequency settings. We measured the imposed expiratory WOB with several PEEP levels during a simulated spontaneous breathing pattern.

The ventilator's contribution to the imposed R_E was greater than that of the ETT with nearly all of the ventilators tested. There were significant differences in ventilator-imposed R_E between the ventilator brands at various PEEP, V_T, and frequency settings. The Babylog 8000plus consistently had the lowest ventilator-imposed R_E in the majority of the test conditions. There was no intrinsic PEEP (> 1 cm H₂O) in any of the test conditions with any ventilator brand. There were also no significant differences in the imposed expiratory WOB between ventilator brands during simulated spontaneous breathing.

The major cause of R_E appears to be the ventilator exhalation valve. Neonatal ventilators that use a set constant flow during inhalation and exhalation appear to have less R_E than ventilators that use a variable bias flow during exhalation. Clinical studies are needed to determine whether the imposed R_E of these ventilator designs impacts gas exchange, lung mechanics, or ventilator weaning.

Chronic obstructive pulmonary disease (COPD) is a rapidly growing public health problem in the United States. It is unclear whether men and women differ in their utilization of ambulatory care or medications prescribed for COPD.

To evaluate sex-related trends in physician-office and out-patient department COPD visits from 1995 through 2004.

We pooled data from the National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) to derive national estimates of out-patient ambulatory COPD visits. For trend analysis we stratified the data into 2-year periods and by sex. The main variables of interest were the number of out-patient visits for COPD, patient characteristics, comorbidities, and medications prescribed.

From 1995 to 2004, COPD-related out-patient visits increased among women and men; oral corticosteroids and short-acting bronchodilators were the most commonly prescribed drugs for both women and men; and prescriptions for inhaled corticosteroid decreased in both women (from 20% to 11%) and men (from 20 to 17%). In 2004, women surpassed men in out-patient COPD visits.

COPD visits increased among both sexes, but the upward trend in COPD visits among women indicates that COPD is no longer a male-dominated disease. Providers should be aware of this shift in patient demographics and the differences between the sexes in COPD management.

The effect of nail polish on pulse oximetry measurements in non-hypoxic subjects has been studied extensively. Some studies found that nail polish decreased pulse-oximetry (S_pO2 ) values, whereas others found no effects from nail polish.

To determine if nail polish affects S_pO2 measurements in mildly hypoxic subjects.

At high altitude, 5 investigators, whose mean oxygen saturation was 91.3% (mild hypoxia), and with 2 brands of pulse oximeter and oximetry probe, obtained S_pO2 measurements from a finger with nail polish and from the matching finger on the opposite hand without nail polish. We tested 9 different nail-polish colors and made 210 pairs of S_pO2 measurements.

The mean ± SD S_pO2 values from the fingers with and without nail polish, respectively, were 91.4 ± 4.1% and 91.2 ± 3.5% (difference –0.2 ± 3.2%, 95% confidence interval 0.2% to 0.4%).

With the pulse oximeters and oximetry probes we tested, nail-polish had no significant effect on S_pO2 in mildly hypoxic healthy subjects.

The benefits of contract learning have been identified in the literature as increased individualization to meet the student's individual needs, promotion of learner independence, and development of lifelong learning behaviors among students.

I used an “action research” approach to implement the contract-learning method into a clinical course. Clinical learning contracts were designed to provide students with the opportunity to focus on any identified areas of unsatisfactory or desired practice. The learning contract specified how the learner would acquire the knowledge and attitudes relevant to their selected learning experience. The learning contract was used as a learning tool and as evidence of the student's development in the clinical experience. Twenty-four senior respiratory therapy students in the College of Health Related Professions, University of Arkansas for Medical Sciences, prepared and used learning contracts during their Clinical Practicum IV. After they had completed the clinical practicum and received their grades, I surveyed the students about their experience with the learning-contract method. The surveys were administered anonymously.

Twenty-one students (88%) returned the surveys. The respondents were overall quite optimistic regarding learning contracts. They generally agreed that they could use the learning contract with confidence and that there is an increase in student autonomy and motivation in scholarship with a learning contract. The median agree/disagree ratings on the survey ranged from 1 (strongly agree) to 2 (agree).

Contract learning is favorable to students' knowledge and skill acquisition and can be incorporated into clinical education of respiratory care students.

No guidelines are available for noninvasive ventilation (NIV) for cystic fibrosis (CF).

To survey and evaluate the use of NIV for CF in France.

We surveyed the coordinator physicians of every accredited CF center in France.

The respondents represented 36 centers (15 pediatric centers, 13 adult centers, and 8 centers that see both pediatric and adult patients), which had a total of 4,416 patients with CF at the time of the study, 168 (3.8%) of whom were using NIV. NIV was being used more often in the adults centers (7.6% of these patients) than in the pediatric centers (1.2% of these patients) or adult-and-pediatric centers (4.1% of these patients) (P = .01). All the respondent centers use NIV as first-line treatment for severe hypercapnic respiratory exacerbation and for stable diurnal hypercapnia, especially when associated with sleep disturbance. Bi-level pressure-targeted ventilation is the preferred ventilation mode. Settings are adjusted based on arterial blood gas values, noninvasive evaluation of patient-ventilator synchrony, patient comfort, and sometimes a sleep study. The surveyed centers reported a number of expected benefits from NIV, but few of those benefits have been proven. Problems with NIV are common and limit its use.

We found a relative homogeneity in these French centers' stated indications for and use of NIV, which highlights their numerous expectations about the benefits of NIV, which contrasts with the few validated benefits. Studies of the benefits of NIV are needed.