Postural effect on gas exchange in patients with unilateral pleural effusions

Improved heart hemodynamics after draining large-volume pleural effusion: a prospective cohort study

Background

Pleural effusion (PE) drainage can relieve the symptoms of dyspnea; however, details of the resulting hemodynamic changes remain undefined.

Methods

Subjects older than 12 years with massive PE requiring pleural drainage were included in this study. Hemodynamic parameters were collected using transthoracic echocardiography at pre-drainage, immediately post-drainage, and 24 h after drainage.

Results

We enrolled 47subjects in this prospective study from June 9, 2015 to September 18, 2016 in Beijing Chaoyang Hospital and 28 subjects were analyzed finally. Draining large-volume PE led to a progressive increase in left ventricular end-diastolic volume index, left atrial volume index, right ventricular area, right atrial area, left ventricular ejection fraction, stroke volume, and tricuspid annular plane systolic excursion, both immediately (P < 0.05) and 24 h after drainage (P < 0.05). The cardiac diastolic measurement ratios of early-transmitral flow velocity to diastolic mitral annular velocity and myocardial performance index decreased significantly following drainage (P < 0.05). More parameters were influenced by left-sided PE drainage. The correlation between effusion volume and changes in echocardiographic measurements was not statistically significant.

Conclusions

Improved preload, and systolic and diastolic function is pivotal for hemodynamic change after draining large PE volumes. Subjects experienced improved cardiac hemodynamics following PE drainage, underlining the beneficial therapeutic and subjective effects.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0625-5) contains supplementary material, which is available to authorized users.

Lateral positioning for critically ill adult patients

BACKGROUND

Critically ill patients require regular body position changes to minimize the adverse effects of bed rest, inactivity and immobilization. However, uncertainty surrounds the effectiveness of lateral positioning for improving pulmonary gas exchange, aiding drainage of tracheobronchial secretions and preventing morbidity. In addition, it is unclear whether the perceived risk levied by respiratory and haemodynamic instability upon turning critically ill patients outweighs the respiratory benefits of side-to-side rotation. Thus, lack of certainty may contribute to variation in positioning practice and equivocal patient outcomes.

OBJECTIVES

To evaluate effects of the lateral position compared with other body positions on patient outcomes (mortality, morbidity and clinical adverse events) in critically ill adult patients. (Clinical adverse events include hypoxaemia, hypotension, low oxygen delivery and global indicators of impaired tissue oxygenation.) We examined single use of the lateral position (i.e. on the right or left side) and repeat use of the lateral position (i.e. lateral positioning) within a positioning schedule.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 5), MEDLINE (1950 to 23 May 2015), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1937 to 23 May 2015), the Allied and Complementary Medicine Database (AMED) (1984 to 23 May 2015), Latin American Caribbean Health Sciences Literature (LILACS) (1901 to 23 May 2015), Web of Science (1945 to 23 May 2015), Index to Theses in Great Britain and Ireland (1950 to 23 May 2015), Trove (2009 to 23 May 2015; previously Australasian Digital Theses Program (1997 to December 2008)) and Proquest Dissertations and Theses (2009 to 23 May 2015; previously Proquest Digital Dissertations (1980 to 23 May 2015)). We handsearched the reference lists of potentially relevant reports and two nursing journals.

SELECTION CRITERIA

We included randomized and quasi-randomized trials examining effects of lateral positioning in critically ill adults. We included manual or automated turns but limited eligibility to studies that included duration of body position of 10 minutes or longer. We examined each lateral position versus at least one comparator (opposite lateral position and/or another body position) for single therapy effects, and the lateral positioning schedule (repeated lateral turning) versus other positioning schedules for repetitive therapy effects.

DATA COLLECTION AND ANALYSIS

We pre-specified methods to be used for data collection, risk of bias assessment and analysis. Two independent review authors carried out each stage of selection and data extraction and settled differences in opinion by consensus, or by third party adjudication when disagreements remained unresolved. We planned analysis of pair-wise comparisons under composite time intervals with the aim of considering recommendations based on meta-analyses of studies with low risk of bias.

MAIN RESULTS

We included 24 studies of critically ill adults. No study reported mortality as an outcome of interest. Two randomized controlled trials (RCTs) examined lateral positioning for pulmonary morbidity outcomes but provided insufficient information for meta-analysis. A total of 22 randomized trials examined effects of lateral positioning (four parallel-group and 18 cross-over designs) by measuring various continuous data outcomes commonly used to detect adverse cardiopulmonary events within critical care areas. However, parallel-group studies were not comparable, and cross-over studies provided limited data as the result of unit of analysis errors. Eight studies provided some data; most of these were single studies with small effects that were imprecise. We pooled partial pressure of arterial oxygen (PaO2) as a measure to detect hypoxaemia from two small studies of participants with unilateral lung disease (n = 19). The mean difference (MD) between lateral positions (bad lung down versus good lung down) was approximately 50 mmHg (MD -49.26 mmHg, 95% confidence interval (CI) -67.33 to -31.18; P value < 0.00001). Despite a lower mean PaO2 for bad lung down, hypoxaemia (mean PaO2 < 60 mmHg) was not consistently reported. Furthermore, pooled data had methodological shortcomings with unclear risk of bias. We had similar doubts regarding internal validity for other studies included in the review.

AUTHORS' CONCLUSIONS

Review authors could provide no clinical practice recommendations based on the findings of included studies. Available research could not eliminate the uncertainty surrounding benefits and/or risks associated with lateral positioning of critically ill adult patients. Research gaps include the effectiveness of lateral positioning compared with semi recumbent positioning for mechanically ventilated patients, lateral positioning compared with prone positioning for acute respiratory distress syndrome (ARDS) and less frequent changes in body position. We recommend that future research be undertaken to address whether the routine practice of repositioning patients on their side benefits all, some or few critically ill patients.

Effect of body position on gas exchange in patients with unilateral pleural effusion: influence of effusion volume

The objective of this study was to evaluate the effect of lateral body position on gas exchange in patients with unilateral pleural effusion, with special reference to the influence of effusion volume. Thirty consecutive patients with unilateral pleural effusion, without evidence of parenchymal pulmonary involvement, were entered into the study. Arterial blood gas tensions (PaO2, PaCO2) were randomly measured in both right and left lateral decubitus body positions, while breathing room air. To assess the influence of the effusion volume, roentgenographic and functional parameters were used. Among the latter, FVC, FEV1, TLC and RV were determined. The influence of the presence or absence of pleuritic pain on gas exchange was also assessed. There was no significant difference in PaCO2 between right and left lateral decubitus body positions (31.1 +/- 4.2 vs. 31.0 +/- 4.5 mmHg). The differences in PaO2 between the two body positions ranged from 0.5-25 mmHg (mean 9.3 +/- 6.6 mmHg). Mean PaO2 with the normal-side (control) down (PaO2-N) (81.4 +/- 8.5 mmHg) was higher, but without significant statistical difference, than mean PaO2 with the effusion-side down (PaO2-E) (78.0 +/- 12.5 mmHg). PaO2-N was higher than PaO2-E in 22 of 30 patients (conventional), and lower in eight patients (paradoxical). No consistent relationship was found for alterations in PaO2 in different positions with the volume of effusion, either when estimated by a roentgenographic method or when using spirometric or plethysmographic values.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of body position on gas exchange in patients with unilateral central airway lesions. Down with the good lung?

In this study, we evaluated the effect of body position (erect, supine, and two decubitus positions) on gas exchange (alveolar-arterial PO2 difference [AaPO2]) in 35 patients who had various degrees of lung collapse roentgenographically caused by unilateral central airway lesions, with special reference to the difference in AaPO2 between two lateral decubitus positions. The patients were divided into two groups. Group 1 was composed of 23 patients with FEV1/FVC > 70 percent. In group 2, there were 12 patients with FEV1/FVC < 70 percent. Our results showed that the mean AaPO2 of group 1 patients was least in the lateral decubitus position with normal lung down (AaPO2N), followed by those in the supine position (AaPO2S), in the lateral decubitus position with lesioned lung down (AaPO2L), and in the erect position (AaPO2E). There was no significant difference in AaPO2 obtained in four positions. However, a significantly negative correlation was found between AaPO2NL (AaPO2N minus AaPO2L) and patient's FEV1 (p < 0.05). In group 2 patients, the mean AaPO2E was least, followed by AaPO2L, AaPO2N, and AaPO2S. The changes of body position did not significantly affect gas exchange in group 2 patients. Unlike previous reports, the present study showed that AaPO2N was not exclusively less than AaPO2L in our patients. AaPO2N was higher than AaPO2L in 11 of 23 in group 1 and in 5 of 12 in group 2 patients. In summary, our results indicated that positional changes did not significantly affect gas exchange in the patients with lung collapse roentgenographically caused by unilateral central airway lesions and the dogma "Down with the good lung" could not be applied to these patients flawlessly.