The effect of thoracentesis on lung function and transthoracic electrical bioimpedance

Breathlessness with Pleural Effusion: What Do We Know?

Breathlessness is the most common symptom in individuals with pleural effusion and is often disabling. The pathophysiology of breathlessness associated with pleural effusion is complex. The severity of breathlessness correlates weakly with the size of the effusion. Improvements in ventilatory capacity following pleural drainage are small and correlate poorly with the volume of fluid drained and improvements in breathlessness. Impaired hemidiaphragm function and a compensatory increase in respiratory drive to maintain ventilation appear to be an important mechanism of breathlessness associated with pleural effusion. Thoracocentesis reduces diaphragm distortion and improves its movement; these changes appear to reduce respiratory drive and associated breathlessness by improving the neuromechanical efficiency of the diaphragm.

Bioimpedance Measurement of Knee Injuries Using Bipolar Electrode Configuration

Currently, there is no suitable solution for the point-of-care diagnosis of knee injuries. A potential portable and low-cost technique for accessing and monitoring knee injuries is bioimpedance measurement. This study validated the feasibility of the bipolar electrode configuration for knee bioimpedance measurement with two electrodes placed on a fixed pair of knee acupuncture locations called Xiyan. Then, the study collected 76 valid samples to investigate the relationship between bioimpedance and knee injuries, among whom 39 patients have unilateral knee injuries, and 37 individuals have healthy knees. The self-contrast results indicated that knee injuries caused a reduction of bioimpedance of the knee by about 5% on average, which was detectable at around 100 kHz (p ≈ 0.001). Furthermore, the results analyzed by principal component analysis and support vector machines show that the detection sensitivity can reach 87.18% using the leave-one-out cross-validation. We also proposed a low-cost and portable bioimpedance measurement device that meets the needs for measuring knee joint bioimpedance.

Patterns of pleural pressure amplitude and respiratory rate changes during therapeutic thoracentesis

BACKGROUND

Although the impact of therapeutic thoracentesis on lung function and blood gases has been evaluated in several studies, some physiological aspects of pleural fluid withdrawal remain unknown. The aim of the study was to assess the changes in pleural pressure amplitude (Ppl_ampl) during the respiratory cycle and respiratory rate (RR) in patients undergoing pleural fluid withdrawal.

METHODS

The study included 23 patients with symptomatic pleural effusion. Baseline pleural pressure curves were registered with a digital electronic manometer. Then, the registrations were repeated after the withdrawal of consecutive portions of pleural fluid (200 ml up to 1000 ml and 100 ml above 1000 ml). In all patients the pleural pressure curves were analyzed in five points, at 0, 25%, 50%, 75% and 100% of the relative volume of pleural effusion withdrawn in particular patients.

RESULTS

There were 11 and 12 patients with right sided and left sided pleural effusion, respectively (14 M, 9F, median age 68, range 46-85 years). The most common cause of pleural effusion were malignancies (20 pts., 87%). The median total volume of withdrawn pleural fluid was 1800 (IQR 1500-2400) ml. After termination of pleural fluid withdrawal Ppl_ampl increased in 22/23 patients compared to baseline. The median Ppl_ampl increased from 3.4 (2.4-5.9) cmH₂O to 10.7 (8.1-15.6) cmH₂O (p < 0.0001). Three patterns of Ppl_ampl changes were identified. Although the patterns of RR changes were more diversified, a significant increase between RR at baseline and the last measurement point was found (p = 0.0097).

CONCLUSIONS

In conclusion, therapeutic thoracentesis is associated with significant changes in Ppl_ampl during the respiratory cycle. In the vast majority of patients Ppl_ampl increased steadily during pleural fluid withdrawal. There was also an increase in RR. The significance of these changes should be elucidated in further studies.

TRIAL REGISTRATION

ClinicalTrial.gov, registration number: NCT02192138 , registration date: July 1st, 2014.

Non-Invasive Monitoring of Cardiac Output in Critical Care Medicine

Critically ill patients require close hemodynamic monitoring to titrate treatment on a regular basis. It allows administering fluid with parsimony and adjusting inotropes and vasoactive drugs when necessary. Although invasive monitoring is considered as the reference method, non-invasive monitoring presents the obvious advantage of being associated with fewer complications, at the expanse of accuracy, precision, and step-response change. A great many methods and devices are now used over the world, and this article focuses on several of them, providing with a brief review of related underlying physical principles and validation articles analysis. Reviewed methods include electrical bioimpedance and bioreactance, respiratory-derived cardiac output (CO) monitoring technique, pulse wave transit time, ultrasound CO monitoring, multimodal algorithmic estimation, and inductance thoracocardiography. Quality criteria with which devices were reviewed included: accuracy (closeness of agreement between a measurement value and a true value of the measured), precision (closeness of agreement between replicate measurements on the same or similar objects under specified conditions), and step response change (delay between physiological change and its indication). Our conclusion is that the offer of non-invasive monitoring has improved in the past few years, even though further developments are needed to provide clinicians with sufficiently accurate devices for routine use, as alternative to invasive monitoring devices.

Temporal evolution of thoracocentesis-induced changes in spirometry and respiratory muscle pressures

BACKGROUND

Several studies investigated the effects of thoracocentesis on aspects of respiratory function without generally ensuring absence of coexistent lung pathology or homogeneity in initial size of the effusion.

METHODS

We studied 90 patients aged 61.6±15.9 years (mean±SD) separated into a group A with small-sized or medium-sized effusion (A=56 patients) and a group B with large and massive one (B=34 patients). There was no significant lung lesion or cardiovascular pathology. The basic spirometric parameters and maximal respiratory pressures were recorded on three instances: just before thoracocentesis (T1), 30 min after completion of the procedure (T2) and after 48 hours (T3).

RESULTS

At T2 vs T1, groups A and B respectively presented significant change (mean±SD) (increase) in forced vital capacity (FVC) of 0.071±0.232 and 0.139±0.224 L, in forced expiratory volume in 1 s (FEV₁) of 0.127±0.231 and 0.201±0.192 L, in FEV₁/FVC of 2.8% and 4.9%, in peak expiratory flow rate (PEFR) of 0.342±0.482 and 0.383±0.425 L/s, in maximal expiratory pressure (MEP) of 0.049±0.037 and 0.049±0.039 kPa and in maximal inspiratory pressure (MIP) of 0.040±0.041 kPa only in group A while decrease in MIP with significant change of 0.055±0.051 kPa in group B. At T3 vs T2 in groups A and B, there was significant change (decrease) in FEV₁/FVC of 2.7% and 4.6% as well as significant change (increase) in MIP of 0.036±0.046 and 0.115±0.060 and in MEP of 0.049±0.043 and 0.070±0.048 kPa.

CONCLUSIONS

Thoracocentesis is associated with progressive-small relative to the volume of fluid removed-increases in lung volumes. In larger effusions at T2, a transient decrease in MIP is observed presumably due to temporary geometric distortion of the diaphragm immediately after fluid removal.

The effects of pleural fluid drainage on respiratory function in mechanically ventilated patients after cardiac surgery

Background

Pleural effusions occur commonly after cardiac surgery and the effects of drainage on gas exchange in this population are not well established. We examined pulmonary function indices following drainage of pleural effusions in cardiac surgery patients.

Methods

We performed a retrospective study examining the effects of pleural fluid drainage on the lung function indices of patients recovering from cardiac surgery requiring mechanical ventilation for more than 7 days. We specifically analysed patients who had pleural fluid removed via an intercostal tube (ICT: drain group) compared with those of a control group (no effusion, no ICT).

Results

In the drain group, 52 ICTs were sited in 45 patients. The mean (SD) volume of fluid drained was 1180 (634) mL. Indices of oxygenation were significantly worse in the drain group compared with controls prior to drainage. The arterial oxygen tension (PaO₂)/fractional inspired oxygen (FiO₂) (P/F) ratio improved on day 1 after ICT placement (mean (SD), day 0: 31.01 (8.92) vs 37.18 (10.7); p<0.05) and both the P/F ratio and oxygenation index (OI: kPa/cm H₂O=PaO₂/mean airway pressure×FiO₂) demonstrated sustained improvement to day 5 (P/F day 5: 39.85 (12.8); OI day 0: 2.88 (1.10) vs day 5: 4.06 (1.73); both p<0.01). The drain group patients were more likely to have an improved mode of ventilation on day 1 compared with controls (p=0.028).

Conclusions

Pleural effusion after cardiac surgery may impair oxygenation. Drainage of pleural fluid is associated with a rapid and sustained improvement in oxygenation.

Feasibility of bioelectrical impedance spectroscopy measurement before and after thoracentesis

Background. Bioelectrical impedance spectroscopy is applied to measure changes in tissue composition. The aim of this study was to evaluate its feasibility in measuring the fluid shift after thoracentesis in patients with pleural effusion. Methods. 45 participants (21 with pleural effusion and 24 healthy subjects) were included. Bioelectrical impedance was analyzed for “Transthoracic,” “Foot to Foot,” “Foot to Hand,” and “Hand to Hand” vectors in low and high frequency domain before and after thoracentesis. Healthy subjects were measured at a single time point. Results. The mean volume of removed pleural effusion was 1169 ± 513 mL. The “Foot to Foot,” “Hand to Hand,” and “Foot to Hand” vector indicated a trend for increased bioelectrical impedance after thoracentesis. Values for the low frequency domain in the “Transthoracic” vector increased significantly (P < 0.001). A moderate correlation was observed between the amount of removed fluid and impedance change in the low frequency domain using the “Foot to Hand” vector (r = −0.7). Conclusion. Bioelectrical impedance changes in correlation with the thoracic fluid level. It was feasible to monitor significant fluid shifts and loss after thoracentesis in the “Transthoracic” vector by means of bioelectrical impedance spectroscopy. The trial is registered with Registration Numbers IRB EK206/11 and NCT01778270.

Expiratory flow limitation in patients with pleural effusion

BACKGROUND

Expiratory flow limitation (EFL) is one of the main mechanisms contributing to dyspnea in patients with chronic obstructive pulmonary disease but has not been explored in patients with pleural effusion.

OBJECTIVES

It was the aim of this study to determine whether patients with pleural effusion exhibit EFL and to investigate the effect of therapeutic thoracentesis on EFL.

PATIENTS AND METHODS

The study was performed on 21 patients with pleural effusion who were subjected to thoracentesis and measurement of pleural pressure (PP). Spirometry and estimation of flow limitation by the negative expiratory pressure technique were performed before and after thoracentesis.

RESULTS

Statistically significant differences were observed in all spirometric parameters. No correlation between the increase in lung volumes and flows and any of the aspirated fluid parameters was observed. Before thoracentesis, 14 out of 21 patients were flow limited, compared with 7 patients after thoracentesis (chi(2) = 6.151, p = 0.013). Mean values of flow limitation before and after thoracentesis differed significantly. The decrease in flow limitation did not correlate with the increase in the spirometric parameters, the aspirated fluid volume or PP decrease.

CONCLUSIONS

In the majority of patients with pleural effusion, flow limitation improves after thoracentesis. Flow limitation may be a contributing factor to the sensation of dyspnea in these patients.

Pleural effusions in lung transplant recipients: image-guided small-bore catheter drainage

PURPOSE

To assess the efficacy of treating pleural effusions in lung transplant recipients with small-bore catheter drainage.

MATERIALS AND METHODS

Chest radiographs and computed tomographic (CT) scans obtained in 31 lung transplant recipients who had pleural effusions treated with catheter drainage were retrospectively reviewed. Duration of drainage and volume of fluid drained were recorded. Results were evaluated 1 and 3 months after chest tube removal. There was complete response (CR) when no pleural fluid remained, partial response (PR) when fluid remaining was less than the pretreatment level, and no response (NR) when fluid recurred to a level at or above the pretreatment level. Associations between cause of effusion (empyema, parapneumonic effusion, rejection, other), response (CR, PR, NR), and type of transplantation (unilateral, bilateral) were examined by using chi2 tests.

RESULTS

Of 31 patients, 25 had bilateral effusions; eight of these 25 patients had small-bore catheters inserted bilaterally. Nine patients had multiple sequential catheter insertions. Duration of drainage ranged from 2 to 44 days (median, 6 days). Fluid output was 110-9,726 mL (median, 1,350 mL). One-month follow-up data were available for 31 of 39 treated pleural effusions: 11 (35%) had CR, 18 (58%) had PR, and two (6%) had NR (percentages do not add up to 100% due to rounding). Three-month follow-up data were available for 28 of 39 treated effusions: 22 (79%) had CR, five (18%) had PR, and one (4%) had NR (percentages do not add up to 100% due to rounding). One- and 3-month response rates, respectively, were not related to cause of effusion (P =.82 and.535) or type of transplantation (P =.568 and >.999).

CONCLUSION

Small-bore catheter drainage of persistent pleural effusions in lung transplant recipients is usually successful, but drainage is often prolonged and may require multiple catheter placements.

Blood pressure and plasma catecholamines in acute and prolonged hypoxia: effects of local hypothermia

This study measured the pressor and plasma catecholamine response to local hypothermia during adaptation to hypobaric hypoxia. Eight healthy men were studied at rest and after 10 and 45 min of local cooling of one hand and forearm as well as after 30 min of rewarming at sea level and again 24 h and 5 days after rapid, passive transport to high altitude (4,559 m). Acute mountain sickness scores ranged from 5 to 16 (maximal attainable score: 20) on the first day but were reduced to 0-8 by the fifth day. Systolic blood pressure, heart rate, and plasma epinephrine increased on day 1 at altitude compared with sea level but declined again on day 5, whereas diastolic and mean blood pressures continued to rise in parallel with plasma norepinephrine. With local cooling, an increased vasoactive response was seen on the fifth day at altitude. Very high pressures were obtained, and the pressure elevation was prolonged. Heart rate increased twice as much on day 5 compared with the other two occasions. Thoracic fluid index increased with cooling on day 5, suggesting an increase in pulmonary vascular resistance. In conclusion, prolonged hypoxia seems to elicit an augmented pressor response to local cooling in the systemic and most likely also the pulmonary circulation.