William Howard

Evaluation of the Total Face Mask for Noninvasive Ventilation to Treat Acute Respiratory Failure

BACKGROUND We hypothesized that the total face mask (TFM) would be perceived as more comfortable than a standard oronasal mask (ONM) by patients receiving noninvasive mechanical ventilation (NIV) therapy for acute respiratory failure (ARF) and would be quicker to apply by respiratory therapists. METHODS Sixty patients presenting with ARF were randomized to receive NIV via either an ONM or a TFM. Mask comfort and dyspnea were assessed using visual analog scores. Other outcomes included time required to apply, vital signs and gas exchange at set time points, and early NIV discontinuation rates (ie, stoppage while still requiring ventilatory assistance). RESULTS Mask comfort and dyspnea scores were similar for both groups through 3 h of use. The time required to apply the mask (5 min [interquartile range (IQR), 2-8] vs 3.5 min [IQR, 1.9-5]), and duration of use (15.7 h [IQR, 4.0-49.8]) vs 6.05 h [IQR, 0.9-56.7]) were not significantly different between the ONM and the TFM group, respectively. Except for heart rate, which was higher at baseline in the TFM group, no differences in vital signs or gas exchange were detected between the groups during the first 3 h (P > .05). Early NIV discontinuation rates were similar for both the ONM group and TFM group (40% vs 57.1%); however, eight patients in the TFM group were switched to an ONM within 3 h, and none from the ONM group was switched to a TFM (P < .05). CONCLUSIONS Among patients with ARF requiring NIV, the ONM and TFM were perceived to be equally comfortable and had similar application times. Early NIV discontinuation rates, improvements in vital signs and gas exchange, and intubation and mortality rates were also similar. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT00686257; URL: www.clinicaltrials.gov.

Impact of a national propofol shortage on duration of mechanical ventilation at an academic medical center.

Objective: To measure the impact of a national propofol shortage on the duration of mechanical ventilation. Design: Before–after study. Setting: Three, noncardiac surgery, adult intensive care units at a 320-bed academic medical center. Patients: Consecutive patients requiring mechanical ventilation ≥48 hrs, administered a continuously infused sedative ≥24 hrs, extubated, and successfully discharged from the intensive care unit were compared between before (December 1, 2008 to May 31, 2009) and after (December 1, 2009, to May 31, 2010) a propofol shortage. Intervention: None. Measurements and Main Results: Sedation drug use and common factors affecting time on mechanical ventilation were collected and if found either to differ significantly (p ⩽ .10) between the two groups or to have an unadjusted significant association (p ⩽ .10) with time on mechanical ventilation were included in a multivariable model. The unadjusted analyses revealed that the median (interquartile range) duration of mechanical ventilation increased from 6.7 (9.8; n = 153) to 9.6 (9.5; n = 128) days (p = .02). Fewer after-group patients received ≥24 hrs of continuously infused propofol (94% vs. 15%, p < .0001); more received ≥24 hrs of continuously infused lorazepam (7% vs. 15%, p = .037) and midazolam (30% vs. 81%, p < .0001). Compared with the before group, the after group was younger, had a higher admission Acute Physiology and Chronic Health Evaluation II score, was more likely to be admitted by a surgical service, have acute alcohol withdrawal, and be managed with pressure-controlled ventilation as the primary mode of mechanical ventilation. Of these five factors, only the Acute Physiology and Chronic Health Evaluation II score, admission service, and use of a pressure-controlled ventilation affected duration of mechanical ventilation across both groups. Although a regression model revealed that Acute Physiology and Chronic Health Evaluation II score (p < .0001), admission by a medical service (p = .009), and use of pressure-controlled ventilation (p = .02) each affected duration of mechanical ventilation in both groups, inclusion in either the before- or after-propofol shortage groups (i.e., high vs. low use of propofol) did not affect duration of mechanical ventilation (p = .35). Conclusions: An 84% decrease in propofol use in the adult intensive care units at our academic institution as a result of a national shortage did not affect duration of mechanical ventilation.

Comparison of acute hemodynamic effects of inhaled nitric oxide and inhaled epoprostenol in patients with pulmonary hypertension

Inhaled nitric oxide (iNO) is used for acute vasoreactivity testing in pulmonary arterial hypertension (PAH) patients. Inhaled epoprostenol (iPGI2) has pulmonary selectivity and is less costly. We sought to compare acute hemodynamic effects of iNO (20 ppm) and iPGI2 (50 ng/kg/min) and determine whether their combination has additive effects. We conducted a prospective, single center, randomized, cross-over study in 12 patients with PAH and seven with heart failure with preserved ejection fraction (HFpEF). In PAH patients, iNO lowered mean pulmonary artery pressure (mPAP) by 9 ± 12% and pulmonary vascular resistance (PVR) by 14 ± 32% (mean ± SD). iPGI2 decreased mPAP by 10 ± 12% and PVR by 12 ± 36%. Responses to iNO and iPGI2 in mPAP and PVR were directly correlated (r2 = 0.68, 0.70, respectively, P > 0.001). In HFpEF patients, mPAP dropped by 4 ± 7% with each agent, and PVR dropped by 33 ± 23% with iNO, and by 25 ± 29% with iPGI2 (P = NS). Pulmonary artery wedge pressure (PAWP) increased significantly with iPGI2 versus baseline (20 ± 3 vs. 17 ± 2 mmHg, P = 0.02) and trended toward an increase with iNO and the combination (20 ± 2, 19± 4 mmHg, respectively). There were no additive effects in either group. In PAH patients, the vasodilator effects of iNO and iPGI2 correlated at the doses used, making iPGI2 a possible alternative for testing acute vasoreactivity, but their combination lacks additive effect. Exposure of HFpEF patients to inhaled vasodilators worsens the PAWP without hemodynamic benefit.

Development, implementation, and evaluation of an institutional daily awakening and spontaneous breathing trial protocol: a quality improvement project.

Introduction: While one controlled trial found that a daily awakening and spontaneous breathing trial (DA-SBT) decreases time on mechanical ventilation (MV), there is a paucity of real-world data surrounding the development, implementation, and impact of DA-SBT protocols. We describe a multidisciplinary process improvement effort in 2, 10-bed medical intensive care units (MICUs) at a 330-bed academic medical center that focused on the development, implementation, and evaluation of a new DA-SBT protocol. Methods: A DA-SBT protocol, developed using results from a nursing survey literature and available institutional resources, was implemented after extensive clinician education and institution of quality reminders to boost use. Postprotocol compliance was evaluated. Use of sedation, DA and SBT practices, and clinical outcomes were retrospectively compared between the before and after DA-SBT protocol groups (ie, consecutive MICU patients requiring a continuously infused sedative [CIS] ≥24 hours). Results: In the after group (n = 32), the DA and SBT compliances were 44% and 84%, respectively. Compared with the before group (n = 33), after group patients received CIS on fewer days of MV (100% vs 67%, P = .003) and had their CIS down-titrated by ≥25% on more days of CIS (40% vs 71%, P = .006). Neither total CIS dose (P = .49), total MV days (P = .75), days of MV where a SBT occurred (P = .38), nor episodes of self-extubation (15% vs 6%, P = .43) differed between the 2 groups. Conclusion: Despite the implementation of a DA-SBT protocol that was individualized to clinician preferences and institutional resources and accompanied by substantial education and reminders for use, compliance to the DA component of this protocol was low and duration of MV remained unchanged. Additional quality improvement strategies are needed to overcome barriers to DA-SBT protocol use that may not exist in controlled clinical trials.

Bench Study of a New Device to Display and Maintain Stable Artificial Airway Cuff Pressure

BACKGROUND: Artificial airway cuff pressure should be maintained within a narrow range. Excessive cuff pressure presents a risk of tracheal damage and stenosis. Insufficient cuff pressure adds the risk of secretion leak past the cuff, tidal-volume leakage, and accidental extubation. The available cuff-inflation devices do not address these problems. OBJECTIVE: In the laboratory I developed and evaluated a new cuff-inflation device that continuously displays the cuff pressure and maintains stable cuff pressure. METHODS: The cuff-inflation device evaluation included: test the manometer accuracy; compare the displayed pressure to the pressure delivered to the pilot balloon; determine the devices response to cuff-pressure changes with the addition of 5 mL or 10 mL of air after achieving a 30 cm H2O baseline; measure the VT leak in an intubated artificial trachea by comparing the device results to benchmark measurements; and determine the stability of baseline cuff pressure during routine cuff checks. RESULTS: The mean ± SD bias and precision of devices display, compared to the calibration analyzer, was 1.3 ± 2.6 cm H2O. The pressure delivered by the cuff-inflation devices gas-sampling line to the pilot balloon was equal to the pressure displayed by the cuff-inflation device. With the cuff-inflation device the cuff pressure was unchanged, compared to baseline, after adding 5 mL or 10 mL of air. With 2 current cuff methods, cuff pressure increased to means exceeding 160 cm H2O and 300 cm H2O, respectively. Compared to the benchmark, the difference in exhaled VT mean ± SD bias and precision were: cuff-inflation device 1.4 ± 4.8 mL, and syringe-inflation method 2.4 ± 6.2 mL. Representing a single cuff pressure check, disconnecting the endotracheal-tube pilot balloon from the cuff-inflation devices gas-sampling line and then reconnecting it had no effect on baseline cuff pressure at 2 seconds or 60 seconds. CONCLUSIONS: The cuff-inflation device demonstrated possible improvements over available cuff-inflation devices and cuff-pressure-control methods.

Flow Meters: What Do You Mean the Flow Rate From One Does Not Equal the Same Flow Rate From Another?

Achieving a stable blood oxygen level in patients who depend on this level of care is arguably determined in part by precise regulation of oxygen flow. The reliance on flow meter accuracy is the cautionary message that is relayed in the paper by Davidson et al in this issue of Respiratory Care.[1][1