Background Although lung sliding seen by point-of-care ultrasound (POCUS) is known to be affected to varying degrees by different physiologic and pathologic processes, it is typically only reported qualitatively in the critical care setting. Lung sliding amplitude quantitatively expresses the amount of pleural movement seen by POCUS but its determinants in mechanically ventilated patients are largely unknown. Methods This was a single-center, prospective, observational pilot study examining 40 hemithoraces in 20 adult patients receiving mechanical ventilation. Each subject had lung sliding amplitude measured in both B-mode and by pulsed wave Doppler at their bilateral lung apices and bases. Differences in lung sliding amplitude were correlated with anatomical location (apex vs base) as well as physiologic parameters including positive end expiratory pressure (PEEP), driving pressure, tidal volume and the ratio of arterial partial pressure of oxygen (PaO2) to fraction of inspired oxygen (FiO2). Results POCUS lung sliding amplitude was significantly lower at the lung apex compared to the lung base in both B-mode (3.6 ± 2.0 mm vs 8.6 ± 4.3 mm; p < 0.001) and the pulsed wave Doppler mode (10.3 ± 4.6 cm/s vs 13.9 ± 5.5 cm/s; p < 0.001) corresponding to expected distribution of ventilation to the lung bases. Inter-rater reliability of B-mode measurements was excellent (ICC = 0.91) and distance traversed in B-mode had a significant positive correlation with pleural line velocity (r2 = 0.32; p < 0.001). There was a non-statistically significant trend towards lower lung sliding amplitude for PEEP ≥ 10 cmH2O, as well as for driving pressure ≥ 15 cmH2O in both ultrasound modes. Conclusion POCUS lung sliding amplitude was significantly lower at the lung apex than the lung base in mechanically ventilated patients. This was true when using both B-mode and pulsed wave Doppler. Lung sliding amplitude did not correlate with PEEP, driving pressure, tidal volume or PaO2:FiO2 ratio. Our findings suggest that lung sliding amplitude can be quantified in mechanically ventilated patients in a physiologically predictable way and with high inter-rater reliability. A better understanding of POCUS derived lung sliding amplitude and its determinants may aid in the more accurate diagnosis of lung pathologies, including pneumothorax, and could serve as a means of further reducing radiation exposure and improving outcomes in critically ill patients.

Chronic diseases and musculoskeletal conditions are responsible for a significant portion of the global disease burden and are frequently comorbid, such as with low back pain in patients who also have chronic organ disease. Low back pain is the leading cause of long-term disability and is the most common reason adults seek adjunctive treatment, including osteopathic manipulative treatment (OMT). OMT has been shown to be effective in relieving low back pain and improving back-specific functioning. In this narrative review, the authors summarize literature published in the last decade and analyze the relationship between musculoskeletal disorders and systemic medical conditions such as diabetes mellitus; they also discuss the efficacy and cost-effectiveness of OMT in managing somatic dysfunction in patients with chronic diseases.

PURPOSE:Currently, lung sliding is only thought of in qualitative termsit is either present or it is not. However, our knowledge of pulmonary physiology supports the notion that the amount of lung movement should differ between patients and between different lung regions in the same patient. This line of thinking is in opposition to the binary way in which lung sliding is currently being interpreted. There is little to no knowledge pertaining to this phenomenon. METHODS:This was an observational pilot study of 20 hemithoraces in 10 adult patients admitted to the medical ICU and receiving mechanical ventilation. Each patient had pleural ultrasound performed at the bilateral lung apices and bases. At each anatomical point, both 2D images and pulse wave Doppler measurements were obtained. The amount of lung sliding in the 2D ultrasound imaging mode was quantified by measuring the distance traversed by either visible pleural defects or B-lines over the course of a single respiratory cycle. Pulse wave Doppler values were quantified by recording peak velocity at the pleural line and averaging over the course of three respiratory cycles. RESULTS:The lung sliding distance traversed in B-mode was significantly lower at the apex vs. the base (4.4AE2.5 mm vs 8.1AE5.3 mm; p¼0.003). Pleural line velocity measured in the pulse wave Doppler mode was also significantly lower at the apex vs. the base (11.4AE5.7 cm/s vs base 15.2AE7.8 cm/s; p¼0.01) Distance traversed in B-mode had a strong positive correlation with pleural line velocity (r 2 =0.4; p¼0.0001). Distance traversed in B-mode had a weak negative correlation with patient age (r 2 =0.16; p¼0.04) and pleural line velocity had a weak negative correlation with PEEP (r 2 =0.15; p¼0.02). There was no significant correlation with tidal volume, driving pressure or PaO 2 :FiO 2 ratio. CONCLUSIONS:In this pilot study, there was significantly more ultrasound lung movement detected at the lung base compared to the lung apex in mechanically ventilated patients. This finding is consistent with the expected distribution of ventilation in normal lungs. Lung sliding distance in the 2D mode correlated significantly with pulse wave Doppler velocity measurements. Patient age and PEEP had a weak negative correlation with amount of lung sliding. These findings demonstrate that lung sliding can be quantified in a meaningful and physiologically predictable way. A better understanding of the lung regions in which lung sliding will be most obvious may aid in the more accurate diagnosis of pneumothorax and other lung pathologies. Future studies will aim to build on this pilot data by quantifying lung sliding in specific lung pathologies. CLINICAL IMPLICATIONS:The ability to quantify ultrasound lung sliding may aid in the more accurate diagnosis of pneumothorax and other lung pathologies in critically ill patients.