Breathing pattern during acute respiratory failure and recovery

Abstract

The objective of this study was to compare the breathing pattern of patients who failed to wean from mechanical ventilation to the pattern during acute respiratory failure. We hypothesized that a similar breathing pattern occurs under both conditions. Breathing pattern, mouth occlusion pressure (P0.1) and maximum inspiratory pressure (PI,max) were measured in 15 patients during acute respiratory failure, within 24 h of the institution of mechanical ventilation, and in 49 patients during recovery, when they were ready for discontinuation from mechanical ventilation. The following indices were calculated: rapid shallow breathing index (respiratory frequency/tidal volume (f R/VT)); rapid shallow breathing-occlusion pressure index (ROP = P0.1·fR/VT); P0.1/PI,max; and effective inspiratory impedance (P0.1/VT/(inspiratory time (t I)).Patients who failed to wean (n=11) had a similar ROP, fR/VT and P0.1/PI,max to those with acute respiratory failure despite a significantly reduced P0.1/VT/t I, the value of which was comparable to that of patients who weaned successfully (n=38). The PI,max of patients who failed to wean was similar to that of patients who weaned successfully.We conclude that patients who failed to wean had a breathing pattern similar to that during acute respiratory failure, despite a reduced mechanical load on the respiratory muscles and a relatively adequate inspiratory muscle strength. This suggests that strategies that enhance respiratory muscle endurance may facilitate weaning.

Effect of Inspiratory Muscle Training on Weaning Success in Critically Ill Intubated Patients

“…The ventilatory pattern of www.intechopen.com patients that are not successfully weaned is similar to that observed during AFR (Del Rosario et al, 1997). Thus, some investigators recommend inspiratory muscle strengthening to reduce respiratory muscle fatigue (Chang, Boots, Brown, et al, 2005) and facilitate weaning from MV (Del Rosario et al, 1997).…”

“…J. Martin, et al, 2005). Although some studies recommend IMT during MV (Chang, Boots, Brown, et al, 2005;Del Rosario, et al, 1997;Sprague & Hopkins, 2003), observed a post-weaning reduction in inspiratory muscle strength in patients submitted to long-term MV.…”

Remifentanil Improves Breathing Pattern and Reduces Inspiratory Workload in Tachypneic Patients

“…In a previous study, patients with acute respiratory failure had a mean RSBI of 140 Ϯ 25 (breaths/min)/L. 2 From that datum we calculated that 14 patients were sufficient to detect RSBI changes of Ͼ 20% with a power of 80% and a significance level of .05. We first compared the 3 conditions without remifentanil (ie, before infusion of placebo, after infusion of placebo, and before infusion of remifentanil) with repeated-measure analysis of variance or the Friedman test, as appropriate.…”

“…[1][2][3] The rapid shallow breathing index (RSBI, respiratory rate divided by V T ) predicts weaning outcome, 4 extubation failure, 5 and time to wean. 6 Rapid shallow breathing is associated with increased ventilatory work load and/or reduction in respiratory muscle strength, and therefore can lead to respiratory muscle fatigue.…”

Weaning from Mechanical Ventilation by Long-Term Nasal Positive Pressure Ventilation in Two Patients with Acute Respiratory Distress Syndrome Associated with Pneumococcal Sepsis

“…Both patients had HRF with inspiratory mouth pressures comparable to patients with acute HRF and those with weaning failure indicating an increased inspiratory load and decreased inspiratory muscle strength even after adequate treatment of pneumonia, sepsis and associated complications [13, 14, 15]. Decreased pulmonary compliance and increased alveolar dead space following fibrosing alveolitis might have contributed to HRF, but this was probably not the only condition which resulted in impairment of the respiratory pump, since fibrosing alveolitis due to ARDS, in general, leads to persistent hypoxemia, but not to hypercapnia [9].…”