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Changes in regional distribution of lung sounds as a function of positive end-expiratory pressure.

Lev S, Glickman YA, Kagan I, Dahan D, Cohen J, Grinev M, Shapiro M, Singer P - Crit Care (2009)

Bottom Line: In patients with unilateral lung pathology, this shift was significant in the diseased lung, but not as pronounced in the other lung.No significant difference in lung sound distribution was encountered based on level of ventilator support needed.No significant difference was encountered between repeated measurements.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of General Intensive Care, Rabin Medical Center, Beilinson Campus, Petach Tikva 49100, Israel. lev.nirit@gmail.com

ABSTRACT

Introduction: Automated mapping of lung sound distribution is a novel area of interest currently investigated in mechanically ventilated, critically ill patients. The objective of the present study was to assess changes in thoracic sound distribution resulting from changes in positive end-expiratory pressure (PEEP). Repeatability of automated lung sound measurements was also evaluated.

Methods: Regional lung sound distribution was assessed in 35 mechanically ventilated patients in the intensive care unit (ICU). A total of 201 vibration response imaging (VRI) measurements were collected at different levels of PEEP between 0 and 15 cmH2O. Findings were correlated with tidal volume, oxygen saturation, airway resistance, and dynamic compliance. Eighty-two duplicated readings were performed to evaluate the repeatability of the measurement.

Results: A significant shift in sound distribution from the apical to the diaphragmatic lung areas was recorded when increasing PEEP (paired t-tests, P < 0.05). In patients with unilateral lung pathology, this shift was significant in the diseased lung, but not as pronounced in the other lung. No significant difference in lung sound distribution was encountered based on level of ventilator support needed. Decreased lung sound distribution in the base was correlated with lower dynamic compliance. No significant difference was encountered between repeated measurements.

Conclusions: Lung sounds shift towards the diaphragmatic lung areas when PEEP increases. Lung sound measurements are highly repeatable in mechanically ventilated patients with various lung pathologies. Further studies are needed in order to fully appreciate the contribution of PEEP increase to diaphragmatic sound redistribution.

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Representative frames (or maps) at peak-inspiratory flow obtained from five individual patients at PEEP levels 0, 5, 10 and 15 cmH2O.  (a) A 74-year-old female with respiratory failure. (b) A 19-year-old male with right pneumothorax. (c) A 83-year-old male with sternal wound infection. (d) A 77-year-old male with myasthenia gravis. (e) A 57-year-old male with acute pancreatitis. PEEP = positive end-expiratory pressure.
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Figure 5: Representative frames (or maps) at peak-inspiratory flow obtained from five individual patients at PEEP levels 0, 5, 10 and 15 cmH2O. (a) A 74-year-old female with respiratory failure. (b) A 19-year-old male with right pneumothorax. (c) A 83-year-old male with sternal wound infection. (d) A 77-year-old male with myasthenia gravis. (e) A 57-year-old male with acute pancreatitis. PEEP = positive end-expiratory pressure.

Mentions: As shown in Figure 4, per patient analysis revealed that when increasing PEEP from 0 to 10 cmH2O, sound energy distribution increased in the diaphragmatic lung areas in 76% of the patients (26 of 34). In these cases, a larger peak-inspiratory flow image was obtained at higher PEEP (examples in Figure 5a and 5b). In several patients, an asymmetrical change of lung sound energy distribution was recorded at PEEP 15 cmH2O (Figure 5c, d, and 5e). Comparisons between VT, SpO2, Cdyn and Raw at two different levels of ADR are summarized in Table 2. When adjusted for RR, no difference in VT, Raw and SpO2was encountered between the two levels of ADR. At RRs lower than 20 breaths/minute, Cdyn tended to be higher for recordings with increased energy in the lower lung regions (ADR < 2). This difference approached significance (P = 0.058).


Changes in regional distribution of lung sounds as a function of positive end-expiratory pressure.

Lev S, Glickman YA, Kagan I, Dahan D, Cohen J, Grinev M, Shapiro M, Singer P - Crit Care (2009)

Representative frames (or maps) at peak-inspiratory flow obtained from five individual patients at PEEP levels 0, 5, 10 and 15 cmH2O.  (a) A 74-year-old female with respiratory failure. (b) A 19-year-old male with right pneumothorax. (c) A 83-year-old male with sternal wound infection. (d) A 77-year-old male with myasthenia gravis. (e) A 57-year-old male with acute pancreatitis. PEEP = positive end-expiratory pressure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2717423&req=5

Figure 5: Representative frames (or maps) at peak-inspiratory flow obtained from five individual patients at PEEP levels 0, 5, 10 and 15 cmH2O. (a) A 74-year-old female with respiratory failure. (b) A 19-year-old male with right pneumothorax. (c) A 83-year-old male with sternal wound infection. (d) A 77-year-old male with myasthenia gravis. (e) A 57-year-old male with acute pancreatitis. PEEP = positive end-expiratory pressure.
Mentions: As shown in Figure 4, per patient analysis revealed that when increasing PEEP from 0 to 10 cmH2O, sound energy distribution increased in the diaphragmatic lung areas in 76% of the patients (26 of 34). In these cases, a larger peak-inspiratory flow image was obtained at higher PEEP (examples in Figure 5a and 5b). In several patients, an asymmetrical change of lung sound energy distribution was recorded at PEEP 15 cmH2O (Figure 5c, d, and 5e). Comparisons between VT, SpO2, Cdyn and Raw at two different levels of ADR are summarized in Table 2. When adjusted for RR, no difference in VT, Raw and SpO2was encountered between the two levels of ADR. At RRs lower than 20 breaths/minute, Cdyn tended to be higher for recordings with increased energy in the lower lung regions (ADR < 2). This difference approached significance (P = 0.058).

Bottom Line: In patients with unilateral lung pathology, this shift was significant in the diseased lung, but not as pronounced in the other lung.No significant difference in lung sound distribution was encountered based on level of ventilator support needed.No significant difference was encountered between repeated measurements.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of General Intensive Care, Rabin Medical Center, Beilinson Campus, Petach Tikva 49100, Israel. lev.nirit@gmail.com

ABSTRACT

Introduction: Automated mapping of lung sound distribution is a novel area of interest currently investigated in mechanically ventilated, critically ill patients. The objective of the present study was to assess changes in thoracic sound distribution resulting from changes in positive end-expiratory pressure (PEEP). Repeatability of automated lung sound measurements was also evaluated.

Methods: Regional lung sound distribution was assessed in 35 mechanically ventilated patients in the intensive care unit (ICU). A total of 201 vibration response imaging (VRI) measurements were collected at different levels of PEEP between 0 and 15 cmH2O. Findings were correlated with tidal volume, oxygen saturation, airway resistance, and dynamic compliance. Eighty-two duplicated readings were performed to evaluate the repeatability of the measurement.

Results: A significant shift in sound distribution from the apical to the diaphragmatic lung areas was recorded when increasing PEEP (paired t-tests, P < 0.05). In patients with unilateral lung pathology, this shift was significant in the diseased lung, but not as pronounced in the other lung. No significant difference in lung sound distribution was encountered based on level of ventilator support needed. Decreased lung sound distribution in the base was correlated with lower dynamic compliance. No significant difference was encountered between repeated measurements.

Conclusions: Lung sounds shift towards the diaphragmatic lung areas when PEEP increases. Lung sound measurements are highly repeatable in mechanically ventilated patients with various lung pathologies. Further studies are needed in order to fully appreciate the contribution of PEEP increase to diaphragmatic sound redistribution.

Show MeSH
Related in: MedlinePlus