OBJECTIVE: Maneuvers assessing fluid responsiveness before an intravascular volume expansion may limit useless fluid administration, which in turn may improve outcomes.
OBJECTIVE: To describe maneuvers for assessing fluid responsiveness in mechanically ventilated patients.
BACKGROUND: The protocol was registered at PROSPERO: CRD42019146781.
UNASSIGNED: PubMed, EMBASE, CINAHL, SCOPUS, and Web of Science were search from inception to 08/08/2023.
METHODS: Prospective and intervention studies were selected.
METHODS: Data for each maneuver were reported individually and data from the five most employed maneuvers were aggregated. A traditional and a Bayesian meta-analysis approach were performed.
RESULTS: A total of 69 studies, encompassing 3185 fluid challenges and 2711 patients were analyzed. The prevalence of fluid responsiveness was 49.9%. Pulse pressure variation (PPV) was studied in 40 studies, mean threshold with 95% confidence intervals (95% CI) = 11.5 (10.5-12.4)%, and area under the receiver operating characteristics curve (AUC) with 95% CI was 0.87 (0.84-0.90). Stroke volume variation (SVV) was studied in 24 studies, mean threshold with 95% CI = 12.1 (10.9-13.3)%, and AUC with 95% CI was 0.87 (0.84-0.91). The plethysmographic variability index (PVI) was studied in 17 studies, mean threshold = 13.8 (12.3-15.3)%, and AUC was 0.88 (0.82-0.94). Central venous pressure (CVP) was studied in 12 studies, mean threshold with 95% CI = 9.0 (7.7-10.1) mmHg, and AUC with 95% CI was 0.77 (0.69-0.87). Inferior vena cava variation (∆IVC) was studied in 8 studies, mean threshold = 15.4 (13.3-17.6)%, and AUC with 95% CI was 0.83 (0.78-0.89).
CONCLUSIONS: Fluid responsiveness can be reliably assessed in adult patients under mechanical ventilation. Among the five maneuvers compared in predicting fluid responsiveness, PPV, SVV, and PVI were superior to CVP and ∆IVC. However, there is no data supporting any of the above mentioned as being the best maneuver. Additionally, other well-established tests, such as the passive leg raising test, end-expiratory occlusion test, and tidal volume challenge, are also reliable.

The association between intraoperative nociception and increased patient\'s morbidity is well established. However, hemodynamic parameters, such as heart rate and blood pressure, may result in an inadequate monitor of nociception during surgery. Over the last two decades, different devices have been marketed to \"reliably\" detect intraoperative nociception. Since the direct measure of nociception is impractical during surgery, these monitors measures nociception surrogates such as sympathetic and parasympathetic nervous systems responses (heart rate variability, pupillometry, skin conductance), electroencephalographic changes, and muscular reflex arc. Each monitor carries its own advantages and disadvantages. The manuscript aims to give an overview of the most up-to-date information available in the literature on current nociceptor monitors available in clinical practice, with particular focus on their applications in pediatrics.

Depth-based plethysmography (DPG) for the measurement of respiratory parameters is a mobile and cost-effective alternative to spirometry and body plethysmography. In addition, natural breathing can be measured without a mouthpiece, and breathing mechanics can be visualized. This paper aims at showing further improvements for DPG by analyzing recent developments regarding the individual components of a DPG measurement. Starting from the advantages and application scenarios, measurement scenarios and recording devices, selection algorithms and location of a region of interest (ROI) on the upper body, signal processing steps, models for error minimization with a reference measurement device, and final evaluation procedures are presented and discussed. It is shown that ROI selection has an impact on signal quality. Adaptive methods and dynamic referencing of body points to select the ROI can allow more accurate placement and thus lead to better signal quality. Multiple different ROIs can be used to assess breathing mechanics and distinguish patient groups. Signal acquisition can be performed quickly using arithmetic calculations and is not inferior to complex 3D reconstruction algorithms. It is shown that linear models provide a good approximation of the signal. However, further dependencies, such as personal characteristics, may lead to non-linear models in the future. Finally, it is pointed out to focus developments with respect to single-camera systems and to focus on independence from an individual calibration in the evaluation.

There are several methods to measure body composition in preterm infants. Yet, there is no agreement on which method should be preferred.
PubMed, Embase.com, Wiley/Cochrane Library, and Google Scholar were searched for studies that reported on the predictive value or validity of body composition measurements in preterms, up to 6 months corrected age.
Nineteen out of 1884 identified studies were included. Predictive equations based on weight and length indices, body area circumferences, skinfold thickness, bioelectrical impedance, and ultrasound did not show agreement with body composition measured with air displacement plethysmography (ADP), dual-energy x-ray absorptiometry (DXA), magnetic resonance imaging (MRI), or isotope dilution. ADP agreed well with fat mass density measured by isotope dilution (bias -0.002 g/ml, limits of agreement ±0.012 g/ml, n = 14). Fat mass percentage measured with ADP did not agree well with fat mass percentage measured by isotope dilution (limits of agreement up to ±5.8%) and the bias between measurements was up to 2.2%. DXA, MRI, and isotope dilution were not compared to another reference method in preterms.
DXA, ADP, and isotope dilution methods are considered trustworthy validated techniques. Nevertheless, this review showed that these methods may not yield comparable results.
Based on validation studies that were conducted in a limited number of study subjects, weight and length indices, body area circumferences, skinfold thickness, bioelectrical impedance, and ultrasound seem to be a poor representation of body composition in preterm infants. DXA, ADP, and isotope dilution methods are considered trustworthy and validated techniques. Nevertheless, these methods may not yield comparable results.

The saphenous vein (SV) is a hindlimb superficial vein which has aroused a considerable interest because of its implication in chronic venous disease and its use in coronary artery or lower limb bypass grafts. The morphology and patency of the SV are commonly assessed for diagnosis and management, but the dynamic properties of the vein (compliance, elasticity and reactivity, less widely studied) are also fundamental issues. The subject of this review is neither to review the pathologies, nor the treatments or surgical procedures. The goal is to gather together all existing types of investigation on the superficial vein and to focus on the dynamic venous properties in vivo. The data collected indicate that plethysmography (PG) and ultrasound (US) are extensively used to evaluate SV patency, reflux and morphology. Their use to evaluate superficial vein compliance is less widespread but highly necessary. The protocols used via venous occlusion are described and the various parameters used to accurately measure compliance and distensibility versus elasticity are presented and discussed. The advantage of US diameter measurement is shown, including additional pulsatile compliance evaluation. The overview of venous reactivity greatly differs, being poorly studied in vivo, mainly by optical methods in humans or US echotracking in animals. Existing methodologies are potent but could be certainly developed and improved further for better characterization of the SV in human and for investigations of new devices, surgical techniques and pharmacological treatment in preclinical animal studies.

The assessment of respiratory activity based on wearable devices is becoming an area of growing interest due to the wide range of available sensors. Accordingly, this scoping review aims to identify research evidence supporting the use of wearable devices to monitor the tidal volume during both daily activities and clinical settings. A screening of the literature (Pubmed, Scopus, and Web of Science) was carried out in December 2020 to collect studies: i. comparing one or more methodological approaches for the assessment of tidal volume with the outcome of a state-of-the-art measurement device (i.e., spirometry or optoelectronic plethysmography); ii. dealing with technological solutions designed to be exploited in wearable devices. From the initial 1031 documents, only 36 citations met the eligibility criteria. These studies highlighted that the tidal volume can be estimated by using different technologies ranging from IMUs to strain sensors (e.g., resistive, capacitive, inductive, electromagnetic, and optical) or acoustic sensors. Noticeably, the relative volumetric error of these solutions during quasi-static tasks (e.g., resting and sitting) is typically ≥10% but it deteriorates during dynamic motor tasks (e.g., walking). As such, additional efforts are required to improve the performance of these devices and to identify possible applications based on their accuracy and reliability.

Anthropometrics are a set of direct quantitative measurements of the human body\'s external dimensions, which can be used as indirect measures of body composition. Due to a number of limitations of conventional manual techniques for the collection of body measurements, advanced systems using three-dimensional (3D) scanners are currently being employed, despite being a relatively new technique. A systematic review was carried out using Pubmed, Medline and the Cochrane Library to assess whether 3D scanners offer reproducible, reliable and accurate data with respect to anthropometrics. Although significant differences were found, 3D measurements correlated strongly with measurements made by conventional anthropometry, dual-energy X-ray absorptiometry (DXA) and air displacement plethysmography (ADP), among others. In most studies (61.1%), 3D scanners were more accurate than these other techniques; in fact, these scanners presented excellent accuracy or reliability. 3D scanners allow automated, quick and easy measurements of different body tissues. Moreover, they seem to provide reproducible, reliable and accurate data that correlate well with the other techniques used.

Accurate and precise body composition estimates, notably of total body adiposity, are a vital component of in vivo physiology and metabolic studies. The reference against which other body composition approaches are usually validated or calibrated is the family of methods referred to as multicomponent \"body density\" models. These models quantify three to six components by combining measurements of body mass, body volume, total body water, and osseous mineral mass. Body mass is measured with calibrated scales, volume with underwater weighing or air-displacement plethysmography, total body water with isotope dilution, and osseous mineral mass by dual-energy X-ray absorptiometry. Body density is then calculated for use in model as body mass/volume. Studies over the past decade introduced a new approach to quantifying body volume that relies on dual-energy X-ray absorptiometry measurements, an advance that simplifies multicomponent density model development by eliminating the need for underwater weighing or air-displacement plethysmography systems when these technologies are unavailable and makes these methods more accessible to research and clinical programs. This review critically examines these new dual-energy X-ray approaches for quantifying body volume and density, explores their shortcomings, suggests alternative derivation approaches, and introduces ideas for potential future research studies.

Body composition monitoring is important to understand the effect of diet, physical activity, illness and growth on body stores. Body composition determination by accuracy and reproducibility techniques is essential. The objective of this study was to analyze the agreement between body composition techniques in children and adolescents. Literature search was performed using the PubMed, Scielo and Google Scholar databases. Only observational studies realized in children and adolescents that analyze agreement between two or more body composition techniques were included. Thirty studies were included. Dual-energy X-ray absorptiometry, air displacement plethysmography, hydrodensitometry, deuterium dilution and four compartment model were the techniques for body composition measurement and bioelectrical impedance and anthropometry were used to estimate body composition. Agreement and correlation between methods was influenced by study populations and by technique considered as gold standard for comparisons. In conclusion, there is a low agreement between the different methods to assess body composition. Correlation and agreement interpretation are essential for body composition assessment in children and adolescents. Is recommended the use of equations developed and validated in this populations.
El monitoreo de la composición corporal (CC) permite comprender los efectos de la dieta, el ejercicio físico, la presencia de procesos patológicos y el crecimiento en las reservas corporales; de ahí la importancia de su determinación con técnicas exactas y reproducibles. El objetivo de la presente revisión es analizar la concordancia entre las distintas técnicas para evaluar la CC en población infantil y adolescente. Se realizó una búsqueda no sistemática de la literatura en las bases de datos PubMed, Scielo y Google Scholar para identificar estudios cuyo objetivo primario fuera la evaluación de la concordancia entre dos o más métodos de determinación de la CC. Se incluyeron 30 estudios para la revisión. Los métodos identificados para la medición de la CC fueron la absorciometría dual de rayos X, la pletismografía de gases (BOD-POD), la hidrodensitometría, la dilución de deuterio (D2O) y el modelo de cuatro compartimentos, utilizando bioimpedancia eléctrica y antropometría para la estimación. La concordancia y la correlación entre métodos varía según los diferentes grupos poblacionales y la técnica utilizada como método de referencia. Se concluye que existe una baja concordancia entre los distintos métodos para evaluar la composición corporal. La interpretación de la correlación y la concordancia de los diferentes métodos resulta esencial para evaluar la CC en niños y adolescentes. Se sugiere utilizar ecuaciones desarrolladas o validadas para el grupo en estudio.

Introduction: The relationship between parity and health outcomes has been debated in the scientific literature in terms of \'selection-pressure\'. However, no previous review has raised the impacts of parity on spirometric parameters. This Systematic Review aimed to review the impacts of parity on spirometric parameters.Areas covered: PubMed and Scopus were searched on October 1st, 2020, using the combination of the following two medical subject headings: \'Parity\' and \'Respiratory Function Tests\'. Only original articles published in English/French were retained. Ten studies investigated the impacts of parity on spirometric parameters: six included healthy females, three involved unhealthy females [chronic obstructive pulmonary disease, defect in protease inhibitor, and some other conditions] and one included a mixed population of healthy/unhealthy females. The studies reported conflicting results: no impact, positive impact (multiparity is associated with larger forced-expiratory-volume in one second, forced- and slow- vital-capacity, and inspiratory-capacity), or negative impact (multiparous females has lower bronchial flows, higher static volumes, an accelerated lung-aging, a tendency to an obstructive-ventilatory-defect and/or to lung-hyperinflation, and increased protease inhibitor levels).Expert opinion: The ten studies presented some limitations that made data interpretation relatively difficult. Future research to identify the \'real\' impact of parity on spirometric parameters are therefore encouraged.