Bernat Sales

Effect of Leak and Breathing Pattern on the Accuracy of Tidal Volume Estimation by Commercial Home Ventilators: A Bench Study

BACKGROUND: New home ventilators are able to provide clinicians data of interest through built-in software. Monitoring of tidal volume (VT) is a key point in the assessment of the efficacy of home mechanical ventilation. OBJECTIVE: To assess the reliability of the VT provided by 5 ventilators in a bench test. METHODS: Five commercial ventilators from 4 different manufacturers were tested in pressure support mode with the help of a breathing simulator under different conditions of mechanical respiratory pattern, inflation pressure, and intentional leakage. Values provided by the built-in software of each ventilator were compared breath to breath with the VT monitored through an external pneumotachograph. Ten breaths for each condition were compared for every tested situation. RESULTS: All tested ventilators underestimated VT (ranges of −21.7 mL to −83.5 mL, which corresponded to −3.6% to −14.7% of the externally measured VT). A direct relationship between leak and underestimation was found in 4 ventilators, with higher underestimations of the VT when the leakage increased, ranging between −2.27% and −5.42% for each 10 L/min increase in the leakage. A ventilator that included an algorithm that computes the pressure loss through the tube as a function of the flow exiting the ventilator had the minimal effect of leaks on the estimation of VT (0.3%). In 3 ventilators the underestimation was also influenced by mechanical pattern (lower underestimation with restrictive, and higher with obstructive). CONCLUSIONS: The inclusion of algorithms that calculate the pressure loss as a function of the flow exiting the ventilator in commercial models may increase the reliability of VT estimation.

Interpretación de las curvas del respirador en pacientes con insuficiencia respiratoria aguda

Mechanical ventilation is a therapeutic intervention involving the temporary replacement of ventilatory function with the purpose of improving symptoms in patients with acute respiratory failure. Technological advances have facilitated the development of sophisticated ventilators for viewing and recording the respiratory waveforms, which are a valuable source of information for the clinician. The correct interpretation of these curves is crucial for the correct diagnosis and early detection of anomalies, and for understanding physiological aspects related to mechanical ventilation and patient-ventilator interaction. The present study offers a guide for the interpretation of the airway pressure and flow and volume curves of the ventilator, through the analysis of different clinical scenarios.

Telemedicine in Critical Care

Critical care medicine is the specialty that cares for patients with acute life-threatening illnesses where intensivists look after all aspects of patient care. Nevertheless, shortage of physicians and nurses, the relationship between high costs and economic restrictions, and the fact that critical care knowledge is only available at big hospitals puts the system on the edge. In this scenario, telemedicine might provide solutions to improve availability of critical care knowledge where the patient is located, improve relationship between attendants in different institutions and education material for future specialist training. Current information technologies and networking capabilities should be exploited to improve intensivist coverage, advanced alarm systems and to have large critical care databases of critical care signals.

Mechanical ventilation: looking for new paradigms.

Introduction Mechanical ventilation has improved immensely since its beginnings, when ventilators were far from capable of meeting patients’ needs. Although the vast majority of technical shortcomings have been remedied, many bedside mechanical ventilation problems have yet to be overcome. Has technological innovation failed? No, it is merely insufficient. As suggested in a Conference Summary of the Institute of Medicine [1], reaping full benefits of innovation in diagnostics, therapeutics and devices requires parallel innovations in the way in which healthcare is delivered. The results of the recent multinational Sentinel Events Evaluation study [2 ] showed that the most frequent unintended commission events that compromise patient safety in intensive care units (ICUs) were related to medication, indwelling lines, airway and equipment failure. Therefore, clinicians need to develop surveillance strategies to reduce the risks for specific types of hazards [3].