Arterial blood gases were analyzed in the supine, right and left lateral decubitus positions and the AaPO 2 was calculated in 44 randomly selected patients In 26 patients, individual Pa O 2 with the normal lung in the dependent position was higher than that with the diseased lung; the opposite was true for 18 patients. But how can we utilize positioning for clients with respiratory challenges? Positioning in the supine position is often used to create comfort for the client, to relieve pressure and prevent pain.
Positioning is also used to optimize work health and safety for the caregivers, by helping hold the client or patient still. However, that positioning has a positive effect on respiration is often overlooked.
Normal practice is often to have patients with respiratory difficulties lie down with the head end of the bed elevated at approximately degrees. This is particularly true for the lower half of the lungs as secretion accumulates and fills the alveolar sacs.
In time, this can limit the expansion of the lungs making it harder for the patient to breathe. You might also like: Why is positioning important? In pulmonary physiotherapy, using the lateral recumbent or side-lying position can be a great way of ventilating the lungs.
If the client lies in the right lateral recumbent position, the secretion found in the left lung will be more easily extruded as the lung is ventilated.
Physiological rationale and current evidence for therapeutic positioning of critically ill patients. View 2 excerpts, cites background. An open-access, very-low-field MRI system for posture-dependent 3He human lung imaging. We describe the design and operation of an open-access, very-low-field, magnetic resonance imaging MRI system for in vivo hyperpolarized 3He imaging of the human lungs. This system permits the … Expand. View 1 excerpt, cites background.
In particular, we found a driving pressure in the range of 9 cm H 2 O suggesting low risk for ventilator-induced lung injury in this model of mono-lateral pneumonia. Nevertheless, pulmonary mechanics could be unspecific in monitoring lung injury in this model, and clinical data are needed to evaluate potential association of lateral position with lung injury and clinically-relevant outcomes Similarly, in line with previous data 27 , hemodynamic measurements did not differ between positions.
Yet, it should be taken into account that clinical evidence has shown that mobilization of severely-ill patients can drastically impair hemodynamic stability 16 , 28 , hence risks should be pondered upon indication.
Our in-vivo study provides some original insights that hold clinical promise. First, in clinical settings patients with mono-lateral pneumonia may be kept in the lateral position up to several hours 11 , 12 , Theoretically, a progressive impairment of lung aeration and oedema accumulation over time could be expected, but linear decrease in loss of aeration could not be entirely inferred by our findings and should be corroborated in future experiments also taking into account various ventilatory settings.
Our findings call for translational clinical studies that could further address these key aspects and potentially identify valuable markers to be monitored in order to guide safe duration for lateral position.
Second, although we did not focus on displacement of biofluids in our settings, which was previously studied in small animals 22 , during prolonged lateral positioning infected biofluids seepage into the dependent lung could further compromise lung function and future comprehensive clinical research needs to address these incompletely characterised pathophysiologic mechanisms.
A few limitations of our study should be discussed. First, we used a model of right-lung pneumonia, hence our findings should be carefully extrapolated to left-lateral pneumonia. Nevertheless, our observations are in lines with previous reports in patients with left or right diseased lungs 8 , 9 , 10 , 11 , Second, we only monitored lung derecruitment for 3 h. Lastly, although we conducted inclusive sample size analysis, our population was rather limited in size.
We designed a prospective cross-over randomised experimental study, primarily aimed at evaluating lung aeration dynamics, specifically in the healthy lung, in mechanically-ventilated pigs, with severe mono-lateral pneumonia.
Secondary endpoints were variations in gas exchange, pulmonary mechanics and hemodynamic parameters. Each animal was challenged immediately following preparation and stabilization. Upon instillation, and 20 h thereafter, the animals were kept in lateral-right decubitus to develop right-lung pneumonia. Moreover, bronchoalveolar lavage BAL was performed to confirm the diagnosis of mono-lateral pneumonia.
Figure 5 displays the study protocol. At the end of RM, the previous ventilator settings were restored. Baseline lung ultrasound LUS was performed T0 , then the animal was randomly placed onto the first lateral side Supplementary Content, Randomization List. After min of stabilization in lateral position, baseline hemodynamic parameters, gas exchange, and lung mechanics were measured.
After 3 h, the aforementioned assessments were repeated T1. Then, the animal was placed supine and LUS at T1 was performed. The animal was then positioned on the contralateral side, and aforementioned assessments were performed at baseline T2 and after 3 h T3. Lastly, the animal was placed again in supine position and LUS T3 was recorded. RM, recruitment manoeuvre; LUS, lung ultrasound score. Lung ultrasound was performed by trained intensive care physicians with more than 5-year experience in lung ultrasound imaging.
Each field was divided into a cranial and a caudal subsection, as depicted in Fig. Recorded lung ultrasound images were subsequently evaluated by one operator, blinded to the study interventions time and position of the animal and to randomization order, who computed LUS of both lungs using a four-grade scoring system 31 : 0, normal lung ultrasound multiple horizontal A-lines ; 1, at least three separated B-lines; 2, coalescent B-lines; 3, consolidation.
Per each time of assessment, we computed the total LUS pulmonary score, and right and left lung scores. Thus, LUS score per each hemithorax ranged from 0 to 18; the higher the score, the higher was the loss in pulmonary aeration of a single lung.
Airway pressure and respiratory flow rates were measured as previously reported For a detailed description of methods please see the Supplementary Content Pulmonary Mechanics.
Pulmonary arterial pressure, central venous pressure, pulmonary arterial wedge pressure, core blood temperature, and cardiac output were measured using a Swan—Ganz catheter Swan-Ganz PAC, Edwards Lifesciences, Irvine, CA. The systemic and pulmonary vascular resistances and venous admixture were calculated using standard formulae In order to evaluate the effects of time and position on this animal model, we used a restricted minimum likehood REML analysis for mixed models.
A co variance structure was used to model the within-subjects errors and the Kenward-Roger approximations to estimate denominator degrees of freedom. For each continuous variable, the overall F test was assessed for significance. All post-hoc comparisons were adjusted through Bonferroni correction. Pearson coefficients were used to compute correlation analyses.
We finally conducted a sample size analysis, which is reported in the Supplementary Content. All statistical analyses were performed using SAS software version 9. Vincent, J. International study of the prevalence and outcomes of infection in intensive care units. JAMA , — Article Google Scholar. Cilloniz, C. Acute respiratory distress syndrome in mechanically-ventilated patients with community-acquired pneumonia.
Google Scholar. Hedenstierna, G. Gullo, A. Ventilation and perfusion of each lung during differential ventilation with selective PEEP. Anesthesiology 61 , — Bhuyan, U. Effects of posture on the distribution of pulmonary ventilation and perfusion in children and adults. Thorax 44 , — Tusman, G.
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