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Compression of the lungs by the heart in supine, side-lying, semi-prone positions

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[Purpose] Clarification of the differences in the compression volume of the lungs by the heart (CVLH) between postures may facilitate the selection of optimal postures in respiratory care. Determining CVLH in the supine, semi-prone (Sim’s position), and side-lying positions was the aim of this study. [Subjects and Methods] Eight healthy volunteers (six males, two females; mean age, 29.0 ± 9.2 years) were enrolled in the study. Measurements were performed in the supine, right and left semi-prone, and right and left side-lying positions. semi-prone position was inclined 45° ventrally from the side-lying position. A 1.5-T system with a fast advanced spin-echo sequence in the coronal plane was used for magnetic resonance imaging. [Results] CVLH and heart compression ratio were significantly lower in the semi-prone position on both sides than the other positions. The heart was displaced ventrally when semi-prone and a larger area of the heart leaned on the ventral chest wall, localizing compression to part of the ventral region of the dependent lung. [Conclusion] The region of lungs compressed by the heart is reduced in the semi-prone position due to ventral displacement of the heart. These results suggest that maintaining expansion of the dependent lung is easier in the semi-prone position. © 2016 The Society of Physical Therapy Science. Published by IPEC Inc.
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Compression of the lungs by the heart in supine,
side-lying, semi-prone positions
 , PT, PhD1)*,  , PT2),  , PT, PhD3),
  , PT, PhD3),   , PT, PhD4),  5),
 , PT, PhD1),    , PT1),    , PT1)
1) Department of Physical Therapy, Faculty of Nursing and Rehabilitation, Konan Women’s University:
6-2-23 Morikitamachi, Higashinada, Kobe, Hyogo 658-0001, Japan
2) Department of Rehabilitation, Konan Hospital, Japan
3) Department of Physical Therapy, Uekusa Gakuen Universit y, Japan
4) Department of Physical Therapy, Ibaraki Prefectural University of Health Sciences, Japan
5) Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Japan
Abstract.  
            

 


   

  

     

Key words:
(This article was submitted Mar. 16, 2016, and was accepted May 23, 2016)
INTRODUCTION
           
1)
2)


 3) 4)   
2
5)
            
 6) 

J. Phys. Ther. Sci. 28: 2470–2473, 2016


            
   

The Journal of Physical Therapy Science The Journal of Physical Therapy Science
2471

  


SUBJECTS AND METHODS
  



    
         
    
               





             


1a



   
 







RESU LT S

   



              




DISCUSSION



 2)  
  7)
   

J. Phys. Ther. Sci. Vol. 28, No. 9, 2016
2472




              
         7), pleural
pressure5))
         
Fig. 1.
          
      
 
       
         
   
       
          
 




Tab le 1.
    
3)    
     
   


Fig 2. 

     
 
2473
        
)
6)




4)
)
4)

      

     


REFERENCES
 
     
            [Cro ss

      

          
     
          
   
           
  
 
      
                      
      
         
       
         
     
... Firstly, this may be attributed to keeping the patients undisturbed and then avoiding excessive tracheal irritation caused by head turning and body movement during position switching. Secondly, keeping a prone position is conducive to spontaneous drainage of oropharyngeal secretions, thus avoiding the stimulation of secretion to the larynx and trachea Thirdly, the prone position can provide better overall ventilation/perfusion matching, thus improving respiratory function (e.g., increases in functional residual capacity and arterial partial pressure of oxygen) [20]. In addition, the tongue will fall forward in the prone position, and consequently, the airway will tend to remain open [9,18], thus effectively preventing hypoxemia. ...
Article
Full-text available
Background Conventional supine emergence and prone extubation from general endotracheal anesthesia (GEA) are associated with extubation-related adverse events (ERAEs). Given the minimally invasive nature of endoscopic retrograde cholangiopancreatography (ERCP) as well as the improved ventilation/perfusion matching and easier airway opening in the prone position, we aimed to assess the safety of prone emergence and extubation in patients undergoing ERCP under GEA. Methods Totally, 242 eligible patients were recruited and randomized into the supine extubation group (n = 121; supine group) and the prone extubation group (n = 121; prone group). The primary endpoint was the incidence of ERAEs during emergence, including hemodynamic fluctuations, coughing, stridor, and hypoxemia requiring airway maneuvers. The secondary endpoints included the incidence of monitoring disconnections, extubation time, recovery time, room exit time, and post-procedure sore throat. Results The incidence of ERAEs was significantly lower in the prone group compared with the supine group (8.3% vs 34.7%, OR = 0.17, 95% CI 0.18–0.56; P < 0.001). Moreover, the prone group demonstrated no monitoring disconnections, shorter extubation time and room exit time, faster recovery, and, lower frequency and milder sore throat after the procedure. Conclusions For patients undergoing ERCP under GEA, compared with supine, prone emergence, and extubation had remarkably lower rates of EAREs and better recovery, and can maintain continuous monitoring and improve efficiency. Graphical abstract
... In prone, the Diaphragm shows increased motility in the dorsal regions, freeing the posterior basal segments, enabling expansion [13]. The heart and mediastinum also shift ventrally in prone, reducing the weight on the lungs, recruiting more alveoli [15]. The incomplete prone position (135 degrees) is also a welltolerated position in NIV patients, having similar effects as prone, but to a lesser extent. ...
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Physiotherapy interventions have been evidenced to assist early liberation from ICU in COVID-19 patients. This case series of three COVID patients admitted to the COVID ICU, explains the physiologic rationale of physiotherapy intervention in acute care of COVID patients. Early mobilization is seen to help early recovery. KEY WORDS: Physiologic rationale, COVID, physiotherapy, crocodile breathing.
... From these images, it could be seen that when lying on the left side or left-prone side, due to the effect of gravity, the heart moved down remarkably. But when lying on the right side or right-prone side, the position of heart showed no obvious difference with that in supine [14]. Such changes can also be seen in CT imaging [15,16]. ...
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Background: Several different lying positions, such as lying on the left side, supine, lying on the right side and prone position, existed when healthy people fell asleep. This article explored the influence of lying positions on the shape of ECG (electrocardiograph) waveform during sleep, and then lying position classification based on ECG waveform features and random forest was achieved. Methods: By means of de-noising the overnight sleep ECG data from ISRUC website dataset, as well as extracting the waveform features, we calculated a total of 30 ECG waveform features, including 2 newly proposed features, S/R and ∠QSR. The means and significant difference level of these features within different lying positions were calculated, respectively. Then 12 features were selected for three kinds of classification schemes. Results: The lying positions had comparatively less effect on time-limit features. QT interval and RR interval were significantly lower than that in supine ([Formula: see text]). Significant differences appeared in most of the amplitude and double-direction features. When lying on the left side, the height of P wave and T wave, QRS area and T area, the QR potential difference and ∠QSR were significantly lower than those in supine ([Formula: see text]). However, S/R was significantly greater on left than those in supine ([Formula: see text]) and on right ([Formula: see text]). The height of T wave and area under T wave were significantly higher in supine than those on right ([Formula: see text]). For the subject specific classifier, a mean accuracy of 97.17% with Cohen's kappa statistic κ of 0.91, and AUC > 0.97 were achieved. While the accuracy and κ dropped to 63.87% and 0.32, AUC > 0.66, respectively when the subject independent classifier was considered. Conclusions: When subjects were lying on the left side during sleep, due to the effect of gravity on heart, the position of heart changed, for example, turned and rotated, causing changes in the vectorcardiogram of frontal plane and horizontal plane, which lead to a change in ECG. When lying on the right side, the heart was upheld by the mediastinum, so that the degree of freedom was poor, and the ECG waveform was almost unchanged. The proposed method could be used as a technique for convenient lying position classification.
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Background Two prominent patient positions during thoracoscopic esophagectomy are the left lateral decubitus position (LP) and the prone position (PP). However, whether the patient position during thoracoscopic esophagectomy influences short-term outcomes, especially postoperative pneumonia, remains unclear. We aimed to elucidate the impact of patient position on the occurrence of postoperative pneumonia.Methods We analyzed 9850 patients who underwent oncologic thoracoscopic esophagectomies between 2016 and 2019 from the National Clinical Database. We compared the short-term outcomes between the LP and PP groups, and the primary outcome measure was the incidence of postoperative pneumonia.ResultsThis study included 2637 (26.8%) and 7213 (73.2%) patients in the LP and the PP groups, respectively. The baseline characteristics of the two groups were well-balanced. Compared with the LP group, the PP group had a longer operative time and less blood loss. There were no significant differences in the incidences of postoperative pneumonia, recurrent laryngeal nerve palsy, anastomotic leakage, severe complications, and reoperation between the groups. Meanwhile, prolonged ventilation and surgery-related mortality occurred more frequently in the LP than in the PP group (P < 0.001 and 0.046, respectively). After multivariable adjustment, the patient position did not significantly influence the incidence of postoperative pneumonia (odds ratio 0.91, 95% confidence interval 0.80–1.04).Conclusions Although prolonged ventilation and surgery-related mortality occurred more frequently in the LP group than in the PP group, the patient position did not significantly influence the occurrence of postoperative pneumonia.
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One-lung ventilation (OLV) is a recognized and modifiable risk factor for acute lung injury. OLV needs to be individualized to the patient’s predicted body weight and their particular lung mechanics. Protective OLV is a combination of small, physiologic tidal volumes with consequently low ventilating pressures and routine, individualized PEEP to facilitate open lung ventilation. Ventilator-induced lung injury is preventable by minimizing driving pressure, which is a direct correlate of transpulmonary stress and strain. In patients at particular risk of lung injury, the use of permissive hypercapnia may facilitate a decrease in the mechanical strain onto the lung. Hypoxemia during one-lung ventilation is now rare and often secondary to alveolar de-recruitment in the face of hypoventilation. Management of hypoxemia requires a structured treatment algorithm.
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Objective: To explore the effect of prone positioning on respiratory function in very preterm infants undergoing mechanical ventilation. Methods: A total of 83 very preterm infants treated with mechanical ventilation were enrolled in the study and were randomly assigned to supine group and prone group. Four infants withdrew from the study and 79 infants completed treatment and observation (37 in the supine group and 42 in the prone group). Infants in both groups were mechanically ventilated in a volume assist-control mode. Infants in the prone group were ventilated in the supine position for 4 hours and in the prone position for 2 hours. Ventilator parameters, arterial blood gas analysis, and vital signs were recorded before grouping, every 6 hours in the supine group, and every hour after conversion into the prone position in the prone group, respectively. Results: Fraction of inspired oxygen (FiO2), peak inspiratory pressure, mean inspiratory pressure, and duration of ventilation were significantly lower in the prone group than in the supine group (P<0.05); there were no significant differences in tidal volume or positive end-expiratory pressure between the two groups (P>0.05). The prone group had a significantly higher PO2/FiO2 ratio but significantly lower oxygenation index and respiratory rate than the supine group (P<0.05). There were no significant differences in arterial oxygen tension, pH, base excess, heart rate, or mean blood pressure between the two groups (P>0.05). Conclusions: Alternating ventilation between the prone position and supine position can improve oxygenation function, decrease the fraction of inspired oxygen, and shorten the duration of mechanical ventilation in very preterm infants undergoing mechanical ventilation.
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[Purpose] The purpose of this study was to clarify the benefits of early mobilization for mechanically ventilated patients for their survival to discharge to home from the hospital. [Subjects and Methods] Medical records were retrospectively analyzed of patients who satisfied the following criteria: age ≥ 18 years; performance status 0-2 and independent living at their home before admission; mechanical ventilation for more than 48 h; and survival after mechanical ventilation. Mechanically ventilated patients in the early mobilization (EM) group (n = 48) received mobilization therapy, limb exercise and chest physiotherapy, whereas those in the control group (n = 60) received bed rest alone. Univariate and multivariate logistic regression analyses were performed to identify clinical variables associated with discharge disposition. [Results] Early mobilization was a positive independent factor and the presence of neurological deficits was a negative factor contributing to discharge to home. Among patients surviving mechanical ventilation without neurological deficits, the rate of discharge to home was significantly higher among patients in the EM group that in the control group (76% vs. 40%). [Conclusion] Early mobilization can improve the rate of discharge to home of patients requiring mechanical ventilation because of non-neurological deficits.
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The prone position improves gas exchange in many patients with ARDS. Animal studies have indicated that turning prone restores ventilation to dorsal lung regions without markedly compromising ventral regions. To investigate a potential mechanism by which this might occur, the relative volume of lung located directly under the heart was measured in the supine and prone positions in seven patients. Four axial tomographic sections between the carina and the diaphragm were analyzed (Sections 1 through 4). When supine, the percent of the total lung volume located under the heart increased from 7 +/- 4% to 42 +/- 8%, and from 11 +/- 4% to 16 +/- 4% in Sections 1 through 4, in the left and right lungs, respectively. When prone, the percent of left and right lung volume located under the heart was </= 1 and </= 4 %, respectively, in all four sections (p < 0.05 for each section, supine versus prone). Although a large fraction of the lung, particularly on the left, is located directly under the heart in supine patients, and would be subject to the compressive force resulting from heart weight, almost no lung is located under the heart when patients are prone and the compressive force of the heart is directed towards the sternum.
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Prone posture increases cardiac output and improves pulmonary gas exchange. We hypothesized that, in the supine posture, greater compression of dependent lung limits regional blood flow. To test this, MRI-based measures of regional lung density, MRI arterial spin labeling quantification of pulmonary perfusion, and density-normalized perfusion were made in six healthy subjects. Measurements were made in both the prone and supine posture at functional residual capacity. Data were acquired in three nonoverlapping 15-mm sagittal slices covering most of the right lung: central, middle, and lateral, which were further divided into vertical zones: anterior, intermediate, and posterior. The density of the entire lung was not different between prone and supine, but the increase in lung density in the anterior lung with prone posture was less than the decrease in the posterior lung (change: +0.07 g/cm(3) anterior, -0.11 posterior; P < 0.0001), indicating greater compression of dependent lung in supine posture, principally in the central lung slice (P < 0.0001). Overall, density-normalized perfusion was significantly greater in prone posture (7.9 +/- 3.6 ml.min(-1).g(-1) prone, 5.1 +/- 1.8 supine, a 55% increase; P < 0.05) and showed the largest increase in the posterior lung as it became nondependent (change: +71% posterior, +58% intermediate, +31% anterior; P = 0.08), most marked in the central lung slice (P < 0.05). These data indicate that central posterior portions of the lung are more compressed in the supine posture, likely by the heart and adjacent structures, than are central anterior portions in the prone and that this limits regional perfusion in the supine posture.
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The gravitational gradient of intrapleural pressure is suggested to be less in prone posture than supine. Thus, the gravitational distribution of ventilation is expected to be more uniform prone, potentially affecting regional ventilation-perfusion (V.A/Q.) ratio. Using a novel functional lung magnetic resonance imaging technique to measure regional V.A/Q. ratio, the gravitational gradients in proton density, ventilation, perfusion and V.A/Q. ratio were measured in prone and supine posture. Data were acquired in 7 healthy subjects in a single sagittal slice of the right lung at functional residual capacity. Regional specific ventilation quantified using Specific Ventilation Imaging (SVI) was combined with proton density obtained using a fast gradient-echo sequence to calculate regional alveolar ventilation. Perfusion was measured using arterial spin labeling. Ventilation (ml/min/ml) and perfusion (ml/min/ml) images were registered, smoothed, and divided on a voxel-by-voxel basis to obtain regional V.A/Q. ratio. Data were averaged for voxels within 1 cm gravitational planes starting from the most gravitationally dependent lung. The slope of the relationship between alveolar ventilation and vertical height was less prone than supine (-0.17±0.10 (ml/min/ml)/cm supine, -0.040±0.03 prone, P=0.02) as was the slope of the perfusion-height relationship (-0.14±0.05 (ml/min/ml)/cm supine, -0.08±0.09 prone, P=0.02). There was a significant gravitational gradient in V.A/Q. ratio in both postures (P<0.05) that was less in prone (0.09±0.08 cm-1 supine, 0.04±0.03 prone,P=0.04). The gravitational gradients in ventilation, perfusion, and regional V.A/Q. ratio were greater supine than prone suggesting an interplay between thoracic cavity configuration, airway and vascular tree anatomy, and the effects of gravity on V.A/Q. matching.
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Estimations were made of the vertical gradient of transpulmonary pressure (VGTP) from measurements of esophageal pressure in nine head-up dogs at functional residual capacity (FRC) when alive, when dead, and after total bilateral pneumothorax. The VGTP of 0.4 cmH2O/cm height in the alive state was abolished by pneumothorax, and roentgenograms showed that the heart moved in a caudal-dorsal direction. There was a small but significant increase in the VGTP on going from FRC to near total lung capacity (TLC) in alive head-up dogs. In eight dead head-up dogs heart weight was increased by replacing various amounts of heart blood with Hg. The VGTP was significantly increased from 0.28 to 0.51 cmH2O/cm height. The fractional increase in the VGTP was similar to the fractional increase in heart weight. In five dogs extrapolation to zero heart weight gave an average VGTP of 0.14 cmH2O/cm height. We conclude that the lungs help support the heart in the head-up dog and that the VGTP is in part determined by the pressure distribution required for this support.
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A study of positional variation of anatomic structures in 38 patients undergoing CT in both the supine and prone positions prior to beginning radiotherapy is reported. Within the thorax, turning the patient to the prone position resulted in a ventral shift of hilar structures in 36 of 38 patients. In two patients, pulmonary metastases shifted ventrally and caudally in the prone position. In all cases reviewed, prone positioning produced a ventral shift of the heart and great vessels. Within the abdomen, prone positioning produced ventral as well as caudal shift of both the liver and spleen in 34 of 38 patients. In all of the patients, a ventral shift of the kidneys as well as caudal shift was noted. Little or no variation of position was noted in cervical or pelvic structures with changing body positions.
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Ventilator management decisions in acute lung injury could be better informed with knowledge of the patient's transpulmonary pressure, which can be estimated using measurements of esophageal pressure. Esophageal manometry is seldom used for this, however, in part because of a presumed postural artifact in the supine position. Here, we characterize the magnitude and variability of postural effects on esophageal pressure in healthy subjects to better assess its significance in patients with acute lung injury. We measured the posture-related changes in relaxation volume and total lung capacity in 10 healthy subjects in four postures: upright, supine, prone, and left lateral decubitus. Then, in the same subjects, we measured static pressure-volume characteristics of the lung over a wide range of lung volumes in each posture by using an esophageal balloon catheter. Transpulmonary pressure during relaxation (PLrel) averaged 3.7 (SD 2.0) cmH2O upright and -3.3 (SD 3.2) cmH2O supine. Approximately 58% of the decrease in PLrel between the upright and supine postures was due to a corresponding decrease in relaxation volume. The remaining 2.9-cmH2O difference is consistent with reported values of a presumed postural artifact. Relaxation volumes and pressures in prone and lateral postures were intermediate. To correct estimated transpulmonary pressure for the effect of lying supine, we suggest adding 3 cmH2O (95% confidence interval: -1 to +7 cmH2O). We conclude that postural differences in estimated transpulmonary pressure at a given lung volume are small compared with the substantial range of PLrel in patients with acute lung injury.
Ventilation distribution Physiologic Basis of Respiratory Disease
  • J Milic-Emili
  • Q Hamid
  • J Shannon
  • J Martin