The First Few Hours Off a Respirator

Breathing pattern during acute respiratory failure and recovery

“…However, some patients fail to wean and may require prolonged mechanical ventilation. During weaning trials, these patients typically exhibit a rapid shallow breathing pattern that may result in hypercapnia and impaired gas exchange [4,5]. This breathing pattern is thought to be an adaptive mechanism that avoids the development of overt respiratory muscle fatigue [6].…”

Variability of the Breathing Pattern Before and After Extubation

“…Since the variance of a constant tidal volume is zero, "SP" in equation [2] drops out and "M" becomes unity. According to statistical theory, equation [2] can be rewritten as follows: K 2 Variance (RC) = -Variance (AB) [3] Knowing that the square root of a variance equals the standard deviation (SD), equation [4] is obtained by taking the square root of both sides of equation [3] and solving for K: K=-SD(AB)/SD(RC) [4] Equation [4] allows the proportionality factor (K) to be solved from data collected during natural breathing.…”

“…In order to properly assess a weaning trial, it becomes essential to know the variability of the measured parameters. In stable intensive care unit (ICU) patients on constant FIo2, the arterial oxygen tension can vary by 16.2±10.9 (mean±SD) mm Hg, 3 does not correlate well with the subjective sensation of dyspnea, 4 and is a nonspecific indicator of a successful extubation. Similarly, lung mechanics can be significantly influenced by patient effort and technique.…”

“…Similarly, lung mechanics can be significantly influenced by patient effort and technique. Although Gilbert et al 4 asserted that changes in the breathing pattern were a poor predictor of a successful trial off the ventilator, they compared mechanically controlled ventilation patterns to spontaneous breathing patterns rather than analyzing spontaneous breathing patterns before and after extubation. To our knowledge, no data are available concerning the variability of breathing pattern in a large group of spontaneously breathing, stable patients in the ICU setting for both preextubation and postextubation periods.…”

Respiratory Muscle Failure and Respiratory Failure

“…As a rule, the tidal volume during spontaneous breathing is about half of that on mechanical ventilation, whereas the spontane- ous respiratory rate is approximately double the ventilator rate. [65][66][67] Patients who are able to maintain an adequate tidal volume and respiratory rate can be weaned from mechanical ventilation. However, patients who fail their weaning trial develop rapid, shallow breathing.…”