Influence of Respiratory Behavior on Ventilation, Respiratory Work and Intrinsic PEEP during Noninvasive Nasal Pressure Support Ventilation in Normal Subjects

Abstract

Background: In clinical practice, patients have different inspiratory behaviors during noninvasive pressure support ventilation (PSV): some breathe quietly, others actively help PSV by an additional effort, and others even resist the inspiratory pressure of PSV. Objective: What is the influence of patient collaboration (inspiratory behavior) on the efficiency of PSV? Methods: We ventilated 10 normal subjects with nasal PSV (inspiratory/expiratory: 10/0 and 15/5 cm H₂O) and measured their flow and volume with a pneumotachograph and their esophageal and gastric pressures during three different respiratory voluntary behaviors: relaxed inspiration, active inspiratory work and resisted inspiration. Results: When compared with relaxed inspiration with 10/0 cm H₂O PSV: (1) an active inspiratory effort increased tidal volume (from 789 ± 356 to 1,046 ± 586 ml; p = 0.006), minute ventilation (from 10.40 ± 4.45 to 15.77 ± 7.69 liters/min; p < 0.001), transdiaphragmatic work per cycle (from 0.55 ± 0.33 to 1.72 ± 1.40 J/cycle; p = 0.002) and inspiratory work per cycle (from 0.14 ± 0.20 to 1.26 ± 1.01 J/cycle; p = 0.003); intrinsic positive end-expiratory pressure (PEEP_i) increased from 1.23 ± 1.02 to 3.17 ± 2.30 cm H₂O; p = 0.002); (2) a resisted inspiration decreased tidal volume (to 457 ± 230 ml; p = 0.007), minute ventilation (to 6.93 ± 3.04 liters/min; p = 0.028) along with a decrease in transdiaphragmatic work but no change in PEEP_i. Data obtained during a bilevel PSV of 15/5 cm H₂O were similar to those obtained with the 10/0 cm H₂O settings. Conclusions: Active inspiratory effort increases ventilation during PSV at the expense of an increased breathing work and PEEP_i. Resisted inspiration inversely decreases inspiratory work and ventilation with no air trapping. These differences between inspiratory behaviors could affect the expected beneficial effects of PSV in acutely ill patients.

Nasal high flow in management of children with status asthmaticus: a retrospective observational study

“…Several physiological studies have supported that NIV relieves better work of breathing than continuous positive airway pressure [34, 35] and therefore that it is better than NHF [18]. However, the most recent studies in adults suggest either superiority of NHF over conventional oxygen [36], or equivalence [37] and even superiority over NIV [38].…”

Noninvasive Positive Pressure Ventilation in Patients with Respiratory Failure due to Severe Acute Pancreatitis

“…Noninvasive positive pressure ventilation (NPPV) by face mask provides delivery of assisted MV without the need for an endotracheal intubation [6,7,8]. NPPV has emerged as a significant advance in the management of respiratory failure [9,10,11], especially in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) [12] and cardiogenic pulmonary edema [6, 13].…”

Pressure Support Ventilation Revisited

“…[3] have presented greatly stimulating preliminary data. We encourage them and others to expand upon this work.…”

“…To this end, Vanpee et al [3] have presented data in this issue of Respiration describing the effects of PSV when administered to healthy, awake volunteer subjects. Their subjects performed more respiratory work when actively assisting the inspiratory effort delivered by the ventilator (much in the same way a patient would augment the mechanical inhalation during either PSV or proportional assisted ventilation) when compared to work performed during a passive inhalation.…”