The impact of spontaneous cough on pleural pressure changes during therapeutic thoracentesis.

Cough during therapeutic thoracentesis (TT) is considered an adverse effect. The study was aimed to evaluate the relationship between cough during TT and pleural pressure (Ppl) changes (∆P). Instantaneous Ppl was measured after withdrawal of predetermined volumes of pleural fluid. Fluid withdrawal (FW) and Ppl measurement (PplM) periods were analyzed separately using the two sample Kolmogorov-Smirnov test and the nonparametric skew to assess differences between ∆P distributions in periods with and without cough. The study involved 59 patients, median age 66 years, median withdrawn fluid volume 1800 mL (1330 ÷ 2400 mL). In total, 1265 cough episodes were recorded in 52 patients, in 24% of FW and 19% of PplM periods, respectively. Cough was associated with significant changes in ∆P distribution (p < 0.001), decreasing the left tail of ∆P distribution for FW periods (the skew = - 0.033 vs. - 0.182) and increasing the right tail for PplM periods (the skew = 0.182 vs. 0.088). Although cough was more frequent in 46 patients with normal pleural elastance (p < 0.0001), it was associated with significantly higher ∆P in patients with elevated elastance (median Ppl increase 2.9 vs. 0.2 cmH2O, respectively). Cough during TT is associated with small but beneficial trend in Ppl changes, particularly in patients with elevated pleural elastance, and should not be considered solely as an adverse event.

Impact of therapeutic thoracentesis and pleural pressure changes on breathing pattern, dyspnea, lung function, and arterial blood gases.

INTRODUCTION: Therapeutic thoracentesis is highly effective in providing symptomatic improvement in patients with large volume pleural effusion (PE). However, some physiological effects of pleural fluid (PF) withdrawal are still not fully elucidated. OBJECTIVES: The study aimed to evaluate alterations in the breathing pattern, pulmonary function, and arterial blood gases (ABG) in relation to both withdrawn PF volume and pleural pressure (Ppl) changes in patients undergoing therapeutic thoracentesis. PATIENTS AND METHODS: This prospective, observational, cross­sectional study included 37 patients with large volume PE. Respiratory rate (RR), dyspnea, pulmonary function, and ABG were assessed before the thoracentesis, at the termination of the PF withdrawal and 1, 3, and 24 hours after the procedure. The volume of PF drained, Ppl, and tidal volume (TV) were monitored during the thoracentesis. RESULTS: Thoracentesis resulted in a transient but significant increase in RR directly after the procedure, and a transient decrease, followed by subsequent increase in TV. There was a significant and constant increase in forced vital capacity up to 24 hours after thoracentesis (P = 0.001). Oxygen partial pressure (PaO2) significantly improved directly after PF withdrawal (P = 0.01) and returned to baseline values after 24 hours. Thoracentesis was invariably associated with a significant increase in the amplitude of Ppl (Ppl_ampl) changes during the respiratory cycle (P <0.001). CONCLUSIONS: Therapeutic thoracentesis results in a modest improvement in pulmonary function, tran-sient increase in PaO2 and increase in Ppl_ampl. The improvement in pulmonary function and ABG is closely related to the volume of PF drained and pleural elastance. The increase in Ppl_ampl probably represents a more efficient work of the respiratory muscles.

Independent Lung Ventilation-Experimental Studies on a 3D Printed Respiratory Tract Model.

Independent lung ventilation (ILV) is a life-saving procedure in unilateral pulmonary pathologies. ILV is underused in clinical practice, mostly due to the technically demanding placement of a double lumen endotracheal tube (ETT). Moreover, the determination of ventilation parameters for each lung in vivo is limited. In recent years, the development of 3D printing techniques enabled the production of highly accurate physical models of anatomical structures used for in vitro research, considering the high risk of in vivo studies. The purpose of this study was to assess the influence of double-lumen ETT on the gas transport and mixing in the anatomically accurate 3D-printed model of the bronchial tree, with lung lobes of different compliances, using various ventilation modes. The bronchial tree was obtained from Respiratory Drug Delivery (RDD Online, Richmond, VA, USA), processed and printed by a dual extruder FFF 3D printer. The test system was also composed of left side double-lumen endotracheal tube, Siemens Test Lung 190 and anesthetic breathing bag (as lobes). Pressure and flow measurements were taken at the outlets of the secondary bronchus. The measured resistance increased six times in the presence of double-lumen ETT. Differences between the flow distribution to the less and more compliant lobe were more significant for the airways with double-lumen ETT. The ability to predict the actual flow distribution in model airways is necessary to conduct effective ILV in clinical conditions.

Pleural Pressure Pulse in Patients with Pleural Effusion: A New Phenomenon Registered during Thoracentesis with Pleural Manometry.

Pleural manometry enables the assessment of physiological abnormalities of lung mechanics associated with pleural effusion. Applying pleural manometry, we found small pleural pressure curve oscillations resembling the pulse tracing line. The aim of our study was to characterize the oscillations of pleural pressure curve (termed here as the pleural pressure pulse, PPP) and to establish their origin and potential significance. This was an observational cross-sectional study in adult patients with pleural effusion who underwent thoracentesis with pleural manometry. The pleural pressure curves recorded prior to and during fluid withdrawal were analyzed. The presence of PPP was assessed in relation to the withdrawn pleural fluid volume, lung expandability, vital and echocardiographic parameters, and pulmonary function testing. A dedicated device was developed to compare the PPP to the pulse rate. Fifty-four patients (32 women) median age 66.5 (IQR 58.5-78.7) years were included. Well visible and poorly visible pressure waves were detected in 48% and 35% of the patients, respectively. The frequency of PPP was fully concordant with the pulse rate and the peaks of the oscillations reflected the period of heart diastole. PPP was more visible in patients with a slower respiratory rate (p = 0.008), a larger amount of pleural effusion, and was associated with a better heart systolic function assessed by echocardiography (p < 0.05). This study describes a PPP, a new pleural phenomenon related to the cyclic changes in the heart chambers volume. Although the importance of PPP remains largely unknown, we hypothesize that it could be related to lung atelectasis or lower lung and visceral pleura compliance.

The use of a virtual patient to follow changes in arterial blood gases associated with therapeutic thoracentesis.

PURPOSES:: Some controversies exist on the effect of therapeutic thoracentesis (TT) on arterial blood oxygen tension. The aim of this study was to evaluate this issue using a previously developed virtual patient. METHODS:: The analysis was based and supported by clinical data collected during 36 TT. Pleural pressure and transcutaneous oxygen and carbon dioxide pressures (PtcO2 and PtcCO2) were measured during pleural fluid withdrawal. Arterial blood oxygen tension and arterial CO2 tension (PaO2 and PaCO2) were analysed in simulations that mimicked TT. Minute ventilation was adjusted to maintain arterial CO2 tension at a constant level unless arterial blood oxygen tension fell below 8 kPa. Specifically, the influence of hypoxic pulmonary vasoconstriction efficiency was tested. RESULTS:: In patients, PtcCO2 remained at an approximately constant level (average amplitude: 0.63 ± 0.29 kPa), while some fluctuations of PtcO2 were observed (amplitude: (1.65 ± 1.18 kPa) were observed. In 42% of patients, TT was associated with decrease in PtcCO2. Simulations showed the following: (a) there were similar PaO2 fluctuations in the virtual patient; (b) the lower the hypoxic pulmonary vasoconstriction efficiency, the more pronounced the PaO2 fall during fluid withdrawal; and (c) the lower the atelectatic lung areas recruitment rate, the slower the PaO2 normalization. The decrease in PaO2 was caused by an increase of pulmonary shunt. CONCLUSION:: Therapeutic thoracentesis may cause both an increase and a decrease in PaO2 during the procedure. Pleural pressure decrease, caused by pleural fluid withdrawal, improves the perfusion of atelectatic lung areas. If the rate of recruitment of these areas is low, a lack of ventilation causes the arterial blood oxygen tension to fall. Effective hypoxic pulmonary vasoconstriction may protect against the pulmonary shunt.

The use of a virtual patient to follow pleural pressure changes associated with therapeutic thoracentesis.

PURPOSE: Influence of therapeutic thoracentesis on the pleural pressure (Pp) has been discussed in many clinical studies, however reasons of Pp changes are not precisely established. The aim of the study was to use a previously elaborated virtual cardiopulmonary patient (VP) in analysis of impact of physiological factors on Pp during the procedure. METHODS: Simulations were performed on VP with default values of parameters for which VP simulated the respiratory system of the average 50-year-old healthy Polish woman according to spirometric examination. Alterations of Pp and the amplitude of Pp changes related to breathing (AP) were analyzed. Model parameters related to chosen factors were deviated from their default values to analyze the degree of their impact on Pp and AP. The analysis was based on and supported by our own clinical data. RESULTS: The Pp and AP alteration intensity appeared to be most sensitive to the compliances of the rib cage and mediastinum, and the nonlinearity of the dependence between the recoil pressure and the lung volume: the lower the compliances and the higher the nonlinearity were, the deeper the Pp fall during the procedure and the bigger the AP increase were observed. CONCLUSIONS: Experiments in silico are very useful in analyzing sophisticated physiological and medical problems. They made it possible to show which factors are particularly responsible for changes in Pp during thoracentesis. In the future, they may be useful in establishing objective conditions under which thoracentesis needs to be stopped.