Respiratory Variation Research Articles

Influence of an inspiratory muscle fatigue protocol on older adults on respiratory muscle strength and heart rate variability. A randomized controlled trial

IntroductionInspiratory muscle fatigue has been shown to have effects on the autonomic nervous system and physical condition. This study aimed to evaluate the influence of an inspiratory muscle fatigue protocol on respiratory muscle strength and heart rate variability in older adults.Materials and methodsA randomized controlled clinical trial with double-blinding was carried out involving 24 individuals over 60 years old who demonstrated physical independence in walking and movement. Participants were distributed randomly into three groups: Inspiratory muscle fatigue, activation and control. Measurements of heart rate variability, diaphragmatic ultrasound, and maximum inspiratory pressure were taken at two stages: prior to the intervention (T1) and directly after treatment (T2).ResultsThe inspiratory muscle fatigue group exhibited decrease scores in respiratory and heart rate variability subsequent to undergoing the diaphragmatic fatigue intervention compared to both the activation and control groups (p < 0.05). Conversely, the activation group demonstrated higher values in heart rate variability and respiratory capacity variables following the inspiratory muscle activation training (p < 0.05).ConclusionsFatigue of the inspiratory musculature appears to negatively impact heart rate variability and inspiratory muscle strength in older adults.Clinical trial registrationhttps://clinicaltrials.gov/study/NCT06269042, identifier: NCT06269042.

Abstract 4138624: Looking Beyond Respirophasic Ventricular Interdependence: A Case Report of Constrictive Pericarditis Masquerading as Cirrhosis

Case Presentation: A 67-year-old man with recurrent pleural effusions and concern for cirrhosis was referred for liver transplant. Pleural fluid was transudative by Light’s criteria with a high total protein level of 3.5 g/dL, which made hepatic hydrothorax unlikely. Liver biopsy confirmed congestive hepatopathy without advanced fibrosis. Transthoracic echocardiogram showed left ventricular (LV) ejection fraction 55%, right ventricular (RV) systolic pressure 35 mmHg, normal mitral annular tissue doppler velocities, and early diastolic septal bounce. Right and left heart catheterization showed prominent X and Y descent, elevated and equalized diastolic pressures, but no respiratory discordance in the LV-RV pressure gradient. As etiology of these findings were unclear, he underwent aggressive diuresis and hemodialysis, but repeat right heart catheterization showed persistently elevated right and left filling pressures. Cardiac MRI had no evidence of myocardial or pericardial inflammation/edema but showed pericardial thickening (7.9 mm) and septal bounce. There was no inspiratory septal shift, but the large pleural effusion appeared to limit diaphragm excursion. Given lack of respirophasic ventricular interdependence and thickened pericardium on MRI, CT was ordered, showing pericardial calcifications. Diagnosis of constrictive pericarditis was made, and patient underwent complete pericardiectomy. Pathology confirmed calcified and thick pericardium without acute inflammation. Post-operatively, patient developed RV failure, but recovered with inotrope support and was discharged with improvement in congestive symptoms. Discussion: Constrictive pericarditis classically exhibits respirophasic ventricular interdependence, but large pleural effusions may decrease respiratory variation in intrathoracic pressures, blunting this response. Normal mitral annulus tissue doppler velocities and lack of infiltrative process on cardiac MRI made restrictive cardiomyopathy unlikely. In the absence of respirophasic changes on multimodality testing, constriction can be diagnosed with other supportive features such as diastolic septal bounce, rapid Y descent, diastolic pressure equalization, and pericardial thickening and calcifications.

Respiratory variation of velocity time integral and peak velocity of left ventricular outflow tract for predicting hypotension after induction of general anesthesia in elderly patients

Abstract Background Hypotension after induction of general anesthesia may lead to severe complications in elderly patients. This study investigated whether the respiratory variation of velocity time integral (ΔVTI) and peak velocity (ΔVpeak) of left ventricular outflow tract (LVOT) could predict hypotension after induction of general anesthesia in elderly patients. Methods 120 elderly patients undergoing selective operation under general anesthesia were enrolled in this study. ΔVTI and ΔVpeak of LVOT were measured by transthoracic echocardiography before induction of general anesthesia. After induction, mean arterial pressure (MAP) was recorded every 1 minute for 15 min. Hypotension was defined as a decrease of more than 30% in MAP at baseline or MAP below 65 mmHg from the start of induction. Receiver operating characteristic curves with gray zone and multivariate logistic regression analysis were used to assess the ability of ΔVTI and ΔVpeak of LVOT to predict hypotension after induction of general anesthesia. Results Hypotension occurred in 64 (53.3%) patients after induction of general anesthesia. The area under receiver operating characteristic curves (AUC) for ΔVpeak of LVOT to predict hypotension after induction of general anesthesia was 0.811, and the optimal cutoff value was 13.1% with a gray zone of 9.9% to 13.8%, including 45.0% of patients. The AUC for ΔVTI of LVOT was 0.890, and the optimal cutoff value was 13.8% with a gray zone of 11.1% to 13.9%, including 25.8% of patients. After adjusting for confounders, ΔVTI (Odds ratio = 2.24) and ΔVpeak (Odds ratio = 2.09) of LVOT were two significant independent predictors of hypotension after induction of general anesthesia. Conclusions ΔVTI of LVOT was a reliable predictor of hypotension after the induction of general anesthesia in elderly patients. ΔVpeak of LVOT should be used cautiously to predict hypotension after induction of general anesthesia due to nearly half of elderly patients in the gray zone. Trial registration This study was registered in the Chinese Clinical Trial Registry (registration number: ChiCTR2300077117).

Fluid responsiveness in pediatrics: an unsolved challenge

Predicting fluid responsiveness is a major challenge in the pediatric population as vascular and pulmonary compliance differ from the adults. However it is a crucial thing to avoid the harmful fluid overload. We count on different variables to identify responders being the dynamic parameters the ones with more evidence, specially the Respiratory Variation In Aortic Blood Flow Velocity based on echocardiography. Other variables rely on the arterial waveform, like Pulse Pressure Variation or Stroke Volume Variation seem to have limitations but new tests like VTC are arriving to overcome their drawbacks. We review the actual evidence regarding fluid responsiveness prediction in children and the anatomic and physiologic peculiarities of children that explain why they do not respond like adults and why we should study them in particular.

Computational multiphysics modeling of radioactive aerosol deposition in diverse human respiratory tract geometries

The evaluation of aerosol exposure relies on generic mathematical models that assume uniform particle deposition profiles over the human respiratory tract and do not account for subject-specific characteristics. Here we introduce a hybrid-automated computational workflow that generates personalized particle deposition profiles in 3D reconstructed human airways from computed tomography scans using Computational Fluid and Particle Dynamics simulations. This is the first large-scale study to consider realistic airways variability, where 380 lower and 40 upper human respiratory tract 3D geometries are reconstructed and parameterized. The data is clustered into nine groups using random forest regression. Computational fluid and particle dynamics simulations are conducted on these representative geometries using a realistic heavy-breathing respiratory cycle and radioactive iodine-131 as a source term. Monte Carlo radiation transport simulations are performed to obtain detailed energy deposition maps. Our findings emphasize the importance of personalized studies, as minor respiratory tract variations notably influence deposition patterns rather than global parameters of the lower airways, observing more than 30% variance in the mass deposition fraction.

Machine learning-based estimation of respiratory fluctuations in a healthy adult population using resting state BOLD fMRI and head motion parameters.

External physiological monitoring is the primary approach to measure and remove effects of low-frequency respiratory variation from BOLD-fMRI signals. However, the acquisition of clean external respiratory data during fMRI is not always possible, so recent research has proposed using machine learning to directly estimate respiratory variation (RV), potentially obviating the need for external monitoring. In this study, we propose an extended method for reconstructing RV waveforms directly from resting state BOLD-fMRI data in healthy adult participants with the inclusion of both BOLD signals and derived head motion parameters. In the proposed method, 1D convolutional neural networks (1D-CNNs) used BOLD signals and head motion parameters to reconstruct the RV waveform for the whole fMRI scan time. Resting-state fMRI data and associated respiratory records from the Human Connectome Project in Young Adults (HCP-YA) dataset are used to train and test the proposed method. Compared to using only BOLD-fMRI data for a CNN input, this approach yielded improvements of 14% in mean absolute error, 24% in mean square error, 14% in correlation, and 12% in dynamic time warping. When tested on independent datasets, the method demonstrated generalizability, even in data with different TRs and physiological conditions. This study shows that the respiratory variations could be reconstructed from BOLD-fMRI data in the young adult population, and its accuracy could be improved using supportive data such as head motion parameters. The method also performed well on independent datasets with different experimental conditions.

Hepatic vein Doppler ultrasound to estimate central venous pressure in mechanically ventilated children.

Monitoring central venous pressure (CVP) is crucial for managing critically ill patients yet poses challenges in pediatric cases. This study aimed to correlate CVP with hepatic vein Doppler and IVC ultrasound variables in children. Mechanically ventilated children underwent simultaneous ultrasound and CVP measurements. Hepatic vein Doppler assessed peak velocities (A, S, V, D) and systolic filling fraction. IVC ultrasound included respiratory variability indices, IVC/aorta ratio, and IVC/body surface area ratio. Fifty-three children were included (median age of 8.3months and weight of 6.3kg). Significant correlations were found between CVP values and all hepatic vein Doppler-based variables. The strongest correlation was found between CVP and the sum of the absolute values of the A- and D-wave peak velocities (AD velocity), with a ρ = 0.61 (95% confidence interval [CI] of 0.40 to 0.75; p < 0.001). The AD velocity > 38.55cm/s was able to discriminate patients with CPV > 12mmHg with a sensitivity of 100%, specificity of 95.3%, positive predictive value of 83.3%, and negative predictive value of 100%. No correlations were observed between CVP and variables derived from IVC respiratory variability indices or the IVC/aorta ratio. Conclusion: Hepatic vein Doppler ultrasound provides variables that significantly correlate with CVP and may be useful for estimating cardiac preload in mechanically ventilated children. Indices derived from IVC ultrasound were not reliable for estimating CVP. What is known? • Increased central venous pressure (CVP) can cause interstitial edema and reduce vital organ perfusion, leading to organic dysfunctions, with encapsulated organs such as the kidneys and liver being at higher risk. • However, measuring CVP in children poses challenges due to the difficulties and risks of central venous catheterization, frequent partial or total luminal obstructions in venous catheters, and potential technical errors in measurements. What is new? • Variables obtained through hepatic vein Doppler ultrasonography outperformed those obtained by inferior vena cava ultrasound for estimating CVP in this population. • Hepatic vein Doppler ultrasonography holds potential as an accurate, safe, and non-invasive method for discriminating patients with increased cardiac preload.

Testing preload responsiveness by the tidal volume challenge assessed by the photoplethysmographic perfusion index

BackgroundTo detect preload responsiveness in patients ventilated with a tidal volume (Vt) at 6 mL/kg of predicted body weight (PBW), the Vt-challenge consists in increasing Vt from 6 to 8 mL/kg PBW and measuring the increase in pulse pressure variation (PPV). However, this requires an arterial catheter. The perfusion index (PI), which reflects the amplitude of the photoplethysmographic signal, may reflect stroke volume and its respiratory variation (pleth variability index, PVI) may estimate PPV. We assessed whether Vt-challenge-induced changes in PI or PVI could be as reliable as changes in PPV for detecting preload responsiveness defined by a PLR-induced increase in cardiac index (CI) ≥ 10%.MethodsIn critically ill patients ventilated with Vt = 6 mL/kg PBW and no spontaneous breathing, haemodynamic (PICCO2 system) and photoplethysmographic (Masimo-SET technique, sensor placed on the finger or the forehead) data were recorded during a Vt-challenge and a PLR test.ResultsAmong 63 screened patients, 21 (33%) were excluded because of an unstable PI signal and/or atrial fibrillation and 42 were included. During the Vt-challenge in the 16 preload responders, CI decreased by 4.8 ± 2.8% (percent change), PPV increased by 4.4 ± 1.9% (absolute change), PIfinger decreased by 14.5 ± 10.7% (percent change), PVIfinger increased by 1.9 ± 2.6% (absolute change), PIforehead decreased by 18.7 ± 10.9 (percent change) and PVIforehead increased by 1.0 ± 2.5 (absolute change). All these changes were larger than in preload non-responders. The area under the ROC curve (AUROC) for detecting preload responsiveness was 0.97 ± 0.02 for the Vt-challenge-induced changes in CI (percent change), 0.95 ± 0.04 for the Vt-challenge-induced changes in PPV (absolute change), 0.98 ± 0.02 for Vt-challenge-induced changes in PIforehead (percent change) and 0.85 ± 0.05 for Vt-challenge-induced changes in PIfinger (percent change) (p = 0.04 vs. PIforehead). The AUROC for the Vt-challenge-induced changes in PVIforehead and PVIfinger was significantly larger than 0.50, but smaller than the AUROC for the Vt-challenge-induced changes in PPV.ConclusionsIn patients under mechanical ventilation with no spontaneous breathing and/or atrial fibrillation, changes in PI detected during Vt-challenge reliably detected preload responsiveness. The reliability was better when PI was measured on the forehead than on the fingertip. Changes in PVI during the Vt-challenge also detected preload responsiveness, but with lower accuracy.

Quantifying Posttraumatic Stress Disorder Symptoms During Traumatic Memories Using Interpretable Markers of Respiratory Variability.

Posttraumatic stress disorder (PTSD) causes heightened fight-or-flight responses to traumatic memories (i.e., hyperarousal). Although hyperarousal is hypothesized to cause irregular breathing (i.e., respiratory variability), no quantitative markers of respiratory variability have been shown to correspond with PTSD symptoms in humans. In this study, we define interpretable markers of respiration pattern variability (RPV) and investigate whether these markers respond during traumatic memories, correlate with PTSD symptoms, and differ in patients with PTSD. We recruited 156 veterans from the Vietnam-Era Twin Registry to participate in a trauma recall protocol. From respiratory effort and electrocardiogram measurements, we extracted respiratory timings and rate using a robust quality assessment and fusion approach. We then quantified RPV using the interquartile range and compared RPV between baseline and trauma recall conditions, correlated PTSD symptoms to the difference between trauma recall and baseline RPV (i.e., ∆RPV), and compared ∆RPV between patients with PTSD and trauma-exposed controls. Leveraging a subset of 116 paired twins, we then uniquely controlled for factors shared by co-twins via within-pair analysis for further validation. We found RPV was increased during traumatic memories (p .001), ∆ RPV was positively correlated with PTSD symptoms (p .05), and patients with PTSD exhibited higher ∆ RPV than trauma-exposed controls (p . 05). This paper is the first to elucidate RPV markers that respond during traumatic memories, especially in patients with PTSD, and correlate with PTSD symptoms. These findings encourage future studies outside the clinic, where interpretable markers of respiratory variability are used to track hyperarousal.

Point-of-Care Ultrasound Findings in Occlusive Iliac Vein Thrombus During Pregnancy: A Case Report.

Diagnosing deep venous thromboses and venous thromboemboli (DVT/VTE) in pregnant patients presents a unique challenge for emergency physicians. The risk of DVT/VTE increases during pregnancy, and the potential consequences of misdiagnoses are severe. Point-of-care ultrasonography (POCUS) is frequently a first-line diagnostic imaging modality. However, recent studies have shown a high incidence of thromboses proximal to the common femoral vein during pregnancy, and these would not be visualized using compressive ultrasonography, which traditionally can only visualize thromboses distal to the femoral vein. A 38-year-old female, 25-weeks primiparous, presented to the emergency department with a three-day history of left lower extremity swelling. Point-of-care three-point compression testing was used to evaluate for a DVT; however, no thrombus was visualized. Given high clinical suspicion, color and spectral Doppler testing were performed and demonstrated turbulent flow and reduced respiratory variation in the common femoral vein. This prompted further additional testing for a proximal DVT using magnetic resonance venography, which revealed an occlusive left external iliac thrombus. The patient was subsequently started on daily subcutaneous enoxaparin and discharged home with close follow-up. Emergency physicians play a critical role in evaluations for the presence of DVT/VTE, particularly in pregnant patients. We endorse the use of POCUS with three-point compression testing, as well as color and spectral Doppler imaging, to help identify proximal DVTs in this patient population. This case report can aid physicians in the diagnosis of this pathological condition that if left untreated can have severe consequences.

Variability in sleep architecture and alterations in circadian rhythms in patients with acute cerebral infarction accompanied by sleep-disordered breathing.

To continuously and dynamically monitor the sleep status of patients in the acute phase of cerebral infarction, and to investigate the characteristics of acute cerebral infarction(ACI)associated with sleep-disordered breathing (SDB), variations in sleep structure, and changes in sleep circadian rhythms. Patients with ACI within 48h of onset who were admitted to the Department of Neurology at Kailuan General Hospital from November 2020 to December 2022 were selected. Detailed baseline information such as age, gender, smoking history, drinking history, were recorded for the selected participants. From the beginning of their hospitalization, the selected participants were monitored for their sleep status continuously for 5 days using the Intelligent Mattress-based Sleep Monitoring Platform System(IMSMPS). Based on the heart rate data obtained from the monitoring, the interdaily stability (IS) and intradaily variability (IV) of the sleep circadian rhythm were calculated. 1,367 patients with ACI were selected. Monitoring results over 5 days indicated 147 cases (10.75%) without SDB, and 1,220 cases (89.25%) with SDB. Among the group with SDB, there were 248 cases (18.14%) with continuous mild SDB, 395 cases (28.90%) with moderate SDB, 295 cases (21.58%) with severe SDB, and 282 cases (20.63%) that fluctuated between different severity levels. Within this fluctuating group, 152 cases (53.90%) fluctuated between two severity levels, 120 cases (42.55%) between three levels, and 10 cases (3.55%) among all four levels. There were statistically significant differences (P < 0.05) in the sleep latency, sleep efficiency, non-rapid eye movement stages 1-2, rapid eye movement, proportion of non-rapid eye movement, proportion of rapid eye movement, wake after sleep onset, time out of bed, number of awakenings, respiratory variability index, and heart rate variability index among patients with ACI monitored from day 1 to 5. However, other monitored sleep structure parameters did not show statistically significant differences (P > 0.05). The coefficient of variation for all sleep monitoring parameters ranged between 14.54 and 36.57%. The IV in the SDB group was higher than in the group without SDB (P < 0.05), and the IS was lower than in the group without SDB (P < 0.05). Patients in the acute phase of cerebral infarction have a high probability of accompanying SDB. The sleep structure of these patients shows significant variability based on the onset time of the stroke, and some patients experience fluctuations among different severity levels of SDB. ACI accompanied by SDB can further reduce the IS of a patient's sleep circadian rhythm and increase its IV.

Improving laminar fMRI specificity by reducing macrovascular bias revealed by respiration effects

Abstract Functional MRI (fMRI) time series are inherently susceptible to the influence of respiratory variations. While many studies treat respiration as a source of noise in fMRI, this study employs natural respiratory variations during high resolution (0.8mm) fMRI at 7T to formulate a respiration effect related map and then use this map to reduce macrovascular bias for a more laminar-specific fMRI measurement. Our results indicate that respiratory related signal changes are modulated by breath phase (breathing in/out or in the transition between breath in and out) during fMRI acquisition, with distinct patterns across various brain regions. We demonstrate that respiration maps generated from normal fMRI runs, such as task-oriented sessions, closely resemble those from deep-breath and breath-hold experiments. These maps show a significant correlation with the macro-vasculature automatically segmented based on SWI and QSM images. Most crucially, by removing voxels most responsive to respiratory variations, we can refine high-resolution fMRI measurements to be more layer-specific, improving the accuracy of laminar fMRI analysis.

Is There a Direct Effect Between the Plication of the Myoaponeurotic Layer and the Force of Inspiratory and Expiratory Muscles After Abdominoplasty?

Abdominoplasty may generate an increase in the intra-abdominal pressure (IAP) and consequently an alteration in the pulmonary ventilation. The purpose of this study was to evaluate the potential alterations in the maximal static inspiratory pressure (MIP) and maximal static expiratory pressure (MEP) after abdominoplasty. Thirty-three female patients, aged between 18 and 60, with type III/B Nahas abdominal deformity that underwent abdominoplasty with plication of the anterior rectus and external oblique aponeurosis were selected. The MIP and MEP were measured using a mouthpiece. This is a simple way to indirectly gauge inspiratory and expiratory muscle strength. Measurements were performed before surgery and on the 2nd, 7th, 15th, and 180th postoperative day. In addition, IAP was measured before abdominoplasty and after the placement of compression garment. The MIP and MEP were compared using analysis of variance, followed by the Bonferroni multiple comparison test pairing the different points in time. Paired Student's t test was used for comparing IAP measurements. Pearson's correlation test was used to compare MIP and MEP variations with IAP variation. Results were considered statistically significant when P ≤ 0.05. A decrease was observed in MEP on the 2nd day, with a return close to normal values on the 15th day. In opposition MIP had a surprisingly increase on the 15th postoperative day (129 cmH2O), normalizing 180 days after the operation. A leap in IAP values was revealed at the end of the surgical procedure. It was not possible to establish a positive correlation between the increase of IAP and the alterations of MIP and MEP. There is a decrease in maximum expiratory pressure on the very early postoperative day (2nd postoperative day) and an increase in maximum inspiratory pressure on the 15th postoperative day in patients who underwent abdominoplasty. There was no correlation between the IAP and maximum respiratory pressure variations, both inspiratory and expiratory.

Separation of ventilation and perfusion of electrical impedance tomography image streams using multi-dimensional ensemble empirical mode decomposition

Objective. In the future, thoracic electrical impedance tomography (EIT) monitoring may include continuous and simultaneous tracking of both breathing and heart activity. However, an effective way to decompose an EIT image stream into physiological processes as ventilation-related and cardiac-related signals is missing.Approach. This study analyses the potential of Multi-dimensional Ensemble Empirical Mode Decomposition by application of the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise and a novel frequency-based combination criterion for detrending, denoising and source separation of EIT image streams, collected from nine healthy male test subjects with similar age and constitution.Main results. In this paper, a novel approach to estimate the lung, the heart and the perfused regions of an EIT image is proposed, which is based on the Root Mean Square Error between the index of maximal respiratory and cardiac variation to their surroundings. The summation of the indexes of the respective regions reveals physiologically meaningful time signals, separated into the physiological bandwidths of ventilation and heart activity at rest. Moreover, the respective regions were compared with the relative thorax movement and photoplethysmogram (PPG) signal. In linear regression analysis and in the Bland–Altman plot, the beat-to-beat time course of both the ventilation-related signal and the cardiac-related signal showed a high similarity with the respective reference signal.Significance. Analysis of the data reveals a fair separation of ventilatory and cardiac activity realizing the aimed source separation, with optional detrending and denoising. For all performed analyses, a feasible correlation of 0.587 to 0.905 was found between the cardiac-related signal and the PPG signal.

The effect of laparoscopic pneumoperitoneum on patient’s respiratory variation of inferior vena cava and stroke volume index: A randomized controlled study

Background: The establishment of pneumoperitoneum has impacts on patient’s cardiovascular function. In this study, the respiratory variation of inferior vena cava (IVC), stroke volume (SV) index, and other parameters was monitored to determine how the pneumoperitoneum affects the patient’s hemodynamic and acknowledge how to resolve it. Materials and Methods: Fifty-five patients were randomly divided into Group A (8 mmHg), Group B (10 mmHg), Group C (12 mmHg), Group D (14 mmHg), and Group E (12 mmHg, infusion with 7 mL/kg crystalloid solution). The parameters including IVC variability, SV index, mean artery pressure (MAP), heart rate (HR), cardiac output index (CI), and airway pressure were measured, to compare the changes before and after pneumoperitoneum. Results: Among Group A, Group B, Group C, and Group D, there were no significant differences in patients’ prepneumoperitoneum information. Compare with prepneumoperitoneum, the difference in IVC variability, SV index, MAP, HR, CI, and airway pressure was statistically significant (P &lt; 0.05). After the establishment of pneumoperitoneum, the difference in IVC variability, SV index, and airway pressure among Group A, Group B, Group C, and Group D was statistically significant (P &lt; 0.05). Compare with Group C, the change rates of IVC variability, SV index, MAP, HR, and CI were smaller in Group E (P &lt; 0.05). Conclusion: The establishment of pneumoperitoneum could increase the patient’s IVC variability and reduce SV index, and with the increase of pressure, IVC variability had an increasing trend, SV index had a decreasing trend. Fluid transfusion could reduce the relative influence of the pneumoperitoneum.

Physiological mechanisms behind respiratory variations in right atrial pressure in pulmonary hypertension

Impaired respiratory variation of right atrial pressure (RAP) in severe pulmonary hypertension (PH) suggests difficulty tolerating increased preload during inspiration. Our study explores whether this impairment links to specific factors: right ventricular (RV) diastolic function, elevated RV afterload, systolic RV function, or RV-pulmonary arterial (PA) coupling. We retrospectively evaluated respiratory RAP variation in all participants enrolled in the EXERTION study. Impaired respiratory variation was defined as end-expiratory RAP − end-inspiratory RAP ≤ 2 mm Hg. RV function and afterload were evaluated using conductance catheterization. Impaired diastolic RV function was defined as end-diastolic elastance (Eed) ≥ median (0.19 mm Hg/mL). Seventy-five patients were included; PH was diagnosed in 57 patients and invasively excluded in 18 patients. Of the 75 patients, 31 (41%) had impaired RAP variation, which was linked with impaired RV systolic function and RV-PA coupling and increased tricuspid regurgitation and Eed as compared to patients with preserved RAP variation. In backward regression, RAP variation associated only with Eed. RAP variation but not simple RAP identified impaired diastolic RV function (area under the receiver operating characteristic curve [95% confidence interval]: 0.712 [0.592, 0.832] and 0.496 [0.358, 0.634], respectively). During exercise, patients with impaired RAP variation experienced greater RV dilatation and reduced diastolic reserve and cardiac output/index compared with patients with preserved RAP variation. Preserved RAP variation was associated with a better prognosis than impaired RAP variation based on the 2022 European Society of Cardiology/European Respiratory Society risk score (chi-square P = 0.025) and survival free from clinical worsening (91% vs 71% at 1 year and 79% vs 50% at 2 years [log-rank P = 0.020]; hazard ratio: 0.397 [95% confidence interval: 0.178, 0.884]). Subgroup analyses in patients with group 1 and group 4 PH demonstrated consistent findings with those observed in the overall study cohort. Respiratory RAP variations reflect RV diastolic function, are independent of RV-PA coupling or tricuspid regurgitation, are associated with exercise-induced haemodynamic changes, and are prognostic in PH.Trial registration. NCT04663217.

Contemporary echocardiographic assessment of pericardial effusion and cardiac tamponade

The aim: the aim of this review is to address the challenges in echocardiographic diagnosis of pericardial effusion, which can potentially lead to a lifethreatening condition called cardiac tamponade. This article discusses the possibilities and prognostic value of transthoracic echocardiography in the diagnosis of pericardial effusion and cardiac tamponade.Materials and Methods. An analysis of Russian and foreign literature was conducted using eLibrary and PubMed databases. The following keywords were used: «pericardial effusion», «cardiac tamponade», «constrictive pericarditis», «pericarditis», «pericarditis in echocardiography», «перикардиальный выпот», «перикардит», «тампонада сердца», «диагностика перикардита». The included scientific papers and articles were published from 2013 to 2023. The research method used in the analysis was descriptive-analytical.Results. Pericardial effusion is the accumulation of fluid in the pericardial cavity, which can lead to cardiac tamponade, disrupting normal hemodynamics and cardiac chamber filling, ultimately resulting in systemic hypotension and cardiac arrest. Therefore, it is a life-threatening condition that requires immediate verification, primarily through echocardiography, followed by the determination of treatment strategy. A structured approach, including 2D mode, M-mode, and Doppler echocardiographic assessment, evaluating the quantity and quality of pericardial fluid, cardiac chamber collapse, diastolic ventricular size variability with the respiratory cycle, paradoxical interventricular septum motion, inferior vena cava collapse, respiratory flow variation through valves, and blood flow in hepatic and pulmonary veins, should provide the treating physician with the necessary information for choosing the treatment method. This article discusses key echocardiographic features that will ensure the appropriate assessment of patients with pericardial effusion and/or cardiac tamponade. Among all the mentioned features, the absence of cardiac chamber collapse is likely to have the highest negative prognostic value for excluding cardiac tamponade.

Electrocardiogram Electrode Positioning on the Back During Echocardiography: An Exploratory Cross-Sectional Study.

ECG interpretation is sometimes difficult due to baseline fluctuations and electrode detachments when placed on the subjects' front side, leading to misinterpretation of the rhythms and phases of the cardiac cycle. We aimed to compare the differences in the wave amplitudes and respiratory variations between conventional ECG electrode positioning on the front side of patients and an alternative position on the backs of patients. Echocardiography was performed in 85 patients lying in the left lateral position. We attached the red electrode to the right clavicle, the yellow to the left clavicle, and the green to the left lateral abdomen on the front side of the patients; on the back, we attached the electrode to the right clavicle, the right upper posterior iliac spine, and the left upper posterior iliac spine. The ECG monitor amplitudes were greater on the front side compared to the back side, but the BF-breath values were smaller on the back side (6.0 pixels) compared to the front side (10.5 pixels, p<0.05). The P wave amplitude divided by the BF-breath on the back side was greater than that seen on the front side (2.8 vs. 1.8, p<0.05), whereas the QRS amplitude divided by the BF-breath was 15.0 and 16.3, respectively (p=ns). As an alternative to front-side ECG monitoring, electrodes placed on the back can help avoid misinterpretation of the ECG rhythms and the phases of the cardiac cycle due to respiration during echocardiography.

Acute Pericarditis Manifesting as Persistent Chest Pain Following Primary Percutaneous Coronary Intervention: A Missed Diagnosis

Percutaneous coronary intervention (PCI) is a very rare cause of acute pericarditis. It usually develops after a latent period but can present early in case of procedural complications. A high degree of suspicion is required for diagnosis as most cases can be easily missed. Here, we highlight a case of 54-year-old admitted as a case of non-ST elevated myocardial infarction who in view of ongoing chest pain underwent urgent coronary angiography, followed by the primary PCI to left anterior descending artery after which the patient became pain-free. However, 12 h after the procedure, the patient developed severe persistent chest pain with positional and respiratory variation. He was suspected to have reinfarction and treated accordingly but had no symptomatic improvement and was planned for check angiography. However, based on dynamic electrocardiogram (ECG) changes, new echocardiographic findings aided laboratory parameters, he was diagnosed with acute pericarditis. He was treated with nonsteroidal anti-inflammatory drugs following which his pain resolved and ECG returned to baseline after 4 days. His follow-up echocardiography showed complete resolution of pericardial effusion. This case highlights the importance of keeping acute pericarditis as a differential diagnosis of chest pain in PCI patients. A high degree of suspicion is required, as most cases are easily missed to diagnose.

Accuracy of Pocket-sized Ultrasound Devices to Evaluate Inferior Vena Cava Diameter and Variability in Critically Ill Patients.

By using inferior vena cava (IVC) measurements, clinicians can detect fluid status and responsiveness and find out the etiology of hypotension, acute heart failure, and sepsis easier. Pocket-sized ultrasound devices (PSUD) may take this advantage a few steps further by their lower costs, user-friendly interface, and easily applicable structure.In this study, we aimed to determine the diagnostic value of a PSUD compared with a standard ultrasound device (SD) for the measurement of IVC diameter (IVCD) and its respiratory variability. We measured the inspiratory, expiratory diameters of IVC, and calculated the inferior vena cava collapsibility index (IVCCI). We investigated 42 intensive care unit (ICU) patients. There was no difference in inspiratory (PSUD: 1.34 ± 0.67 cm; SD: 1.35 ± 0.68 cm) and expiratory (PSUD: 1.98 ± 0.53 cm; SD: 2.01 ± 0.49 cm) IVCD among measurements with PSUD and SD (p > 0.05). There was also no difference between IVCCI's measured with PSUD (39 ± 20%) and SD (39 ± 20%) (p > 0.05). The Bland-Altman analysis revealed that the width of 95% limits of agreement were similar for both devices. There was a good inter-device agreement among PSUD and SD for measurements of IVCD, and there was no difference between IVCCI's measured using both ultrasound devices. We support that the idea of a PSUD is as reliable as a SD for IVC measurements. Inci K, Gürsel G. Accuracy of Pocket-sized Ultrasound Devices to Evaluate Inferior Vena Cava Diameter and Variability in Critically Ill Patients. Indian J Crit Care Med 2024;28(4):369-374.