Changes In Respiratory Pattern Research Articles

Falls in oxygen saturations accompany electrographic seizures in term neonates: an observational study.

Effective seizure detection is important however, clinical signs of seizure activity may be subtle in neonates. This study aimed to systematically investigate SpO2 and respiratory pattern changes associated with EEG seizures in term-born neonates. An observational study in term neonates at risk of seizures admitted to a single tertiary level neonatal intensive care unit. Synchronised high-resolution physiological data (ECG, pulse oximetry, respiration) and EEG/amplitude-integrated EEG (aEEG) monitoring were recorded. Sections of traces with evidence of clear EEG seizure activity were compared with physiological data recorded at the same time. 22/44 (50%) neonates who had aEEG monitoring were noted to have electrographic seizures. Physiologic download measurements were available for 11 of these neonates. In nine of these, an acute drop in oxygen saturation (SpO2) of at least 5% was noted in at least one seizure. Accompanying apnoeas were noted in three neonates. Acute decreases in SpO2 were seen in term neonates associated with seizures and these were not always accompanied by an apnoeic episode. Physiologic download in association with EEG monitoring may assist in improving seizure detection. Unexplained drops in SpO2 could indicate further investigation for possible seizures in at-risk neonates. A decrease in blood oxygen saturation (SpO2) associated with EEG seizures can occur in term infants with HIE or perinatal stroke. Drops in SpO2 associated with EEG seizures in term infants with HIE or stroke may occur in the absence of apnoeas. Unexplained acute falls in SpO2 in sick neonates may suggest possible seizures. Drops in SpO2 associated with seizures in term infants can occur over less than 3 minutes. Physiological monitoring alongside EEG monitoring could help to improve seizure detection.

Assessments of perioperative respiratory pattern with non-contact vital sign monitor in children undergoing minor surgery: a prospective observational study.

Nurses routinely assess respiration of hospitalized children; however, respiratory rate measurements are technically difficult due to rapid and small chest wall movements. The aim of this study is to reveal the respiratory status of small children undergoing minor surgery with load cells placed under the bed legs, and to test the hypothesis that respiratory rate (primary variable) is slower immediately after arrival to the ward and recovers in 2h. Continuous recordings of the load cell signals were performed and stable respiratory waves within the 10 discriminative perioperative timepoints were used for respiratory rate measurements. Apnea frequencies were calculated at pre and postoperative nights and 2h immediately after returning to the ward after surgery. Continuous recordings of the load cell signals were successfully performed in 18 children (13 to 119months). Respiratory waves were appraisable for more than 70% of nighttime period and 40% of immediate postoperative period. There were no statistically significant differences of respiratory rate in any timepoint comparisons (p = 0.448), thereby not supporting the study hypothesis. Respiratory rates changed more than 5 breaths per minute postoperatively in 5 out of 18 children (28%) while doses of fentanyl alone did not explain the changes. Apnea frequencies significantly decreased 2h immediately after returning to the ward and during the operative night compared to the preoperative night. Respiratory signal extracted from load cell sensors under the bed legs successfully revealed various postoperative respiratory pattern change in small children undergoing minor surgery. UMIN (University Hospital Information Network) Clinical Registry: UMIN000045579 ( https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000052039 ).

Plethysmograph training: A refinement for collection of respiration data in mice.

Inhaled chemicals can harm the airways. Different effects can result in distinct changes in respiratory patterns; the type of change indicates where and how the respiratory system is affected. Furthermore, changes in respiratory patterns may be detected at much lower substance concentrations than those that cause more serious effects, such as histopathological changes. Changes in respiratory patterns can be studied experimentally by monitoring the breathing of mice placed in plethysmographs and exposing head-outto the test substance. The method is well established; however, it is not known if training mice in being restrained in the plethysmograph could increase the quality of data collection. Here we report the results of training mice to be restrained in plethysmographs for 5 consecutive days, with respect to body weight, respiratory parameters, and time spent in the plethysmograph, before they are removed because of unstable breathing patterns. The mice tolerated the procedure better (measured by time in the plethysmograph) on the second day of training than the first day. Training did not change the breathing parameters between days. Breathing parameters stabilized within 5 min after the mice were placed in the plethysmographs on all days. There was an average of 3% weight loss between the first and last days of the training, indicating that the training procedure placed some strain on the animals. Training reduces the number of mice attempting to escape from the plethysmograph.

The protective effect of inhaled corticosteroid on lung inflammation and breathing pattern complexity in a rat model of asthma

Asthma is a heterogeneous disease in which the complexity of the breathing pattern reduces as the severity of the disease increases. Since the pathophysiological basis of reduced breathing pattern complexity in asthma is unclear, in this study, we investigated the effect of reducing inflammation using an inhaled corticosteroid (fluticasone propionate) on the breathing pattern of a rat model of asthma. Detrended fluctuation analysis, sample entropy, and cross-sample entropy analysis of both inter-breath interval and respiratory volume time series showed that early treatment with inhaled corticosteroids not only diminishes lung inflammation and airway hyper-responsiveness, but also has a protective effect against the reduction of breathing pattern complexity due to asthma. However, late treatment had a partial effect on asthma-induced respiratory pattern changes. Since inflammation is a key factor in shifting breathing dynamics away from normal fluctuations, these findings further emphasize the importance of early treatment of asthma with corticosteroids.

Influence of neonatal endotracheal tube dimensions on oscillometry-acquired reactance: a bench study

Objective. To examine the influence of the endotracheal tube (ETT) on respiratory reactance (Xrs) measured with the forced oscillation technique (FOT) and develop a correction method for it. Approach. In a bench study, the reactance of ETTs (Xtube) with different dimensions was measured on a breathing test lung in various respiratory settings. Main results. Xtube can be accurately predicted by a fitted formula, with an R2 of 0.97, with negligible effects due to changes in respiratory pattern and lung volume. Significance. The developed formula offers the ability to measure ETT-independent Xrs values of patients, improving the potential of FOT for lung function testing in mechanically ventilated newborns.

Hypoxia Differentially Affects Healthy Men and Women During a Daytime Nap With a Dose-Response Relationship: a Randomized, Cross-Over Pilot Study.

Context: The use of daytime napping as a countermeasure in sleep disturbances has been recommended but its physiological evaluation at high altitude is limited. Objective: To evaluate the neuroendocrine response to hypoxic stress during a daytime nap and its cognitive impact. Design, Subject, and Setting: Randomized, single-blind, three period cross-over pilot study conducted with 15 healthy lowlander subjects (8 women) with a mean (SD) age of 29(6) years (Clinicaltrials identifier: NCT04146857, https://clinicaltrials.gov/ct2/show/NCT04146857?cond=napping&draw=3&rank=12). Interventions: Volunteers underwent a polysomnography, hematological and cognitive evaluation around a 90 min midday nap, being allocated to a randomized sequence of three conditions: normobaric normoxia (NN), normobaric hypoxia at FiO2 14.7% (NH15) and 12.5% (NH13), with a washout period of 1 week between conditions. Results: Primary outcome was the interbeat period measured by the RR interval with electrocardiogram. Compared to normobaric normoxia, RR during napping was shortened by 57 and 206 ms under NH15 and NH13 conditions, respectively (p < 0.001). Sympathetic predominance was evident by heart rate variability analysis and increased epinephrine levels. Concomitantly, there were significant changes in endocrine parameters such as erythropoietin (∼6 UI/L) and cortisol (∼100 nmol/L) (NH13 vs. NN, p < 0.001). Cognitive evaluation revealed changes in the color-word Stroop test. Additionally, although sleep efficiency was preserved, polysomnography showed lesser deep sleep and REM sleep, and periodic breathing, predominantly in men. Conclusion: Although napping in simulated altitude does not appear to significantly affect cognitive performance, sex-dependent changes in cardiac autonomic modulation and respiratory pattern should be considered before napping is prescribed as a countermeasure.

Stroke volume variation as an index of fluid responsiveness can be impaired by mental stress.

Cardiac stroke volume variation (SVV) measurement is one of the techniques to detect fluid-responsive hypovolemia in patients under mechanical ventilation. There is an ongoing effort to apply SVV for this purpose also in conscious patients. However, the effect of mental stress often occurring in conscious patients as a potential confounding factor on SVV is not known. The aim of our study was to compare effect of simulated hypovolemia and mental stress on SVV in healthy volunteers in the context of potential confounders - breathing pattern, respiratory sinus arrhythmia magnitude and sex. We examined 102 young healthy volunteers (58 females), mean age 18.6 years. Finger arterial blood pressure was recorded by volume-clamp photoplethysmographic method (Finometer Pro, FMS, Amsterdam, Netherland). From the blood pressure curve, a built in ModelFlow algorithm calculated stroke volume values (SV) for each heartbeat. Respiratory volume was recorded using calibrated respiratory inductive plethysmography (RespiTrace, NIMS, Miami Beach, FL, USA). During four phases of examination protocol (supine rest, head-up tilt (HUT), supine recovery, mental arithmetic task (MA)) we analyzed SVV related to respiratory activity. While during HUT we found an expected increase in SVV together with mean SV decrease, SVV significantly decreased during MA. The observed changes during MA could be attributed to an increased respiratory rate and/or decreased respiratory sinus arrhythmia. Sex related differences in SVV responses to HUT and MA were observed. We conclude that mental stress together with respiratory sinus arrhythmia and respiratory pattern changes can significantly influence SVV as a potential index of fluid responsiveness in conscious patients.

Psychological stress in asthma: repercussions on epigenetics-genetics, immune responses, and pulmonary function in the pediatric population.

In the assessment of childhood asthma, identifying the risk factors associated with exacerbations and broadening this view to understand psychological stress and its repercussions on the inflammatory process of asthma allow a different perspective on this biopsychosocial disease. Psychological stress, as a risk factor for the onset and noncontrol of asthma, has been increasingly evaluated from the perspective of the repercussions on the body of the stimulus generated in the hypothalamic-pituitary axis and adrenal glands, with cortisol release and immune system action. These processes trigger changes in T helper 2 cells, which polarize allergic processes, and dysfunctions in immune tolerance mechanisms, with a decrease in regulatory T cells. Genetic and epigenetic changes in β2-adrenergic and glucocorticoid receptors, with decreased response to these drugs, were also identified in studies, in addition to changes in respiratory function patterns, with worsening of obstruction and inflammation identified via decreased forced expiratory volume in one second and increased exhaled inflammatory gases in allergic asthma. Therefore, the present review sought to identify studies on the effect of personal and parental acute or chronic psychological stress, emphasizing the repercussions on genetics, epigenetics, and immune and pulmonary functional and inflammatory responses in the pediatric population.

Machine-learning based feature selection for a non-invasive breathing change detection

BackgroundChronic Obstructive Pulmonary Disease (COPD) is one of the top 10 causes of death worldwide, representing a major public health problem. Researchers have been looking for new technologies and methods for patient monitoring with the intention of an early identification of acute exacerbation events. Many of these works have been focusing in breathing rate variation, while achieving unsatisfactory sensitivity and/or specificity. This study aims to identify breathing features that better describe respiratory pattern changes in a short-term adjustment of the load-capacity-drive balance, using exercising data.ResultsUnder any tested circumstances, breathing rate alone leads to poor capability of classifying rest and effort periods. The best performances were achieved when using Fourier coefficients or when combining breathing rate with the signal amplitude and/or ARIMA coefficients.ConclusionsBreathing rate alone is a quite poor feature in terms of prediction of breathing change and the addition of any of the other proposed features improves the classification power. Thus, the combination of features may be considered for enhancing exacerbation prediction methods based in the breathing signal.Trial Registration : ClinicalTrials NCT03753386. Registered 27 November 2018, https://clinicaltrials.gov/show/NCT03753386

Machine learning-based data analytic approaches for evaluating post-natal mouse respiratory physiological evolution

Respiratory parameters change during post-natal development, but the nature of their changes have not been well-described. The advent of commercially available plethysmographic instruments provided improved repeatability of measurements and standardization of measured breathing in mice across laboratories. These technologies thus allowed for exploration of more precise respiratory pattern changes during the post-natal developmental epoch. Current methods to analyze respiratory behavior utilize plethysmography to acquire standing values of frequency, volume and flow at specific time points in murine maturation. These metrics have historically been independently analyzed as a function of time with no further analysis examining the interplay these variables have with each other and in the context of postnatal maturation or during blood gas homeostasis. We posit that machine learning workflows can provide deeper physiological understanding into the postnatal development of respiration. In this manuscript, we delineate a machine learning workflow based on the R-statistical programming language to examine how variation and relationships of frequency (f) and tidal volume (TV) change with respect to inspiratory and expiratory parameters. Our analytical workflows could successfully predict age and found that the variation and relationships between respiratory metrics are dynamically shifting with age and during hypercapnic breathing. Thus, our work demonstrates the utility of high dimensional analyses to provide reliable class label predictions using non-invasive respiratory metrics. These approaches may be useful in large-scale phenotyping across development and in disease.

A new house dust mite-driven and mast cell-activated model of asthma in the guinea pig.

Animal models are extensively used to study underlying mechanisms in asthma. Guinea pigs share anatomical, pharmacological and physiological features with human airways and may enable the development of a pre-clinical in vivo model that closely resembles asthma. To develop an asthma model in guinea pigs using the allergen house dust mite (HDM). Guinea pigs were intranasally sensitized to HDM which was followed by HDM challenges once weekly for five weeks. Antigen-induced bronchoconstriction (AIB) was evaluated as alterations in Rn (Newtonian resistance), G (tissue damping) and H (tissue elastance) at the first challenge with forced oscillation technique (FOT), and changes in respiratory pattern upon each HDM challenge were assessed as enhanced pause (Penh) using whole-body plethysmography. Airway responsiveness to methacholine was measured one day after the last challenge by FOT. Inflammatory cells and cytokines were quantified in bronchoalveolar lavage fluid, and HDM-specific immunoglobulins were measured in serum by ELISA. Airway pathology was evaluated by conventional histology. The first HDM challenge after the sensitization generated a marked increase in Rn and G, which was abolished by pharmacological inhibition of histamine, leukotrienes and prostanoids. Repeated weekly challenges of HDM caused increase of Penh and a marked increase in airway hyperresponsiveness for all three lung parameters (Rn , G and H) and eosinophilia. Levels of IgE, IgG1 , IgG2 and IL-13 were elevated in HDM-treated guinea pigs. HDM exposure induced infiltration of inflammatory cells into the airways with a pronounced increase of mast cells. Subepithelial collagen deposition, airway wall thickness and goblet cell hyperplasia were induced by repeated HDM challenge. Repeated intranasal HDM administration induces mast cell activation and hyperplasia together with an asthma-like pathophysiology in guinea pigs. This model may be suitable for mechanistic investigations of asthma, including evaluation of the role of mast cells.

A Study on the Usefulness of Subjective Lumbar Instability Factor for Respiratory Pattern Change and Abdominal Mobility in Peoples with CLBP

A Study on the Usefulness of Subjective Lumbar Instability Factor for Respiratory Pattern Change and Abdominal Mobility in Peoples with CLBP

Postnatal intermittent hypoxia enhances phrenic and reduces vagal upper airway motor activities in rats by epigenetic mechanisms.

What is the central question of this study? What are the alterations in respiratory motor activity that may underlie ventilatory dysfunctions in juvenile and adult animals exposed to postnatal chronic intermittent hypoxia? What is the main finding and its importance? Postnatal chronic intermittent hypoxia modifies the motor activity to pumping and upper airway respiratory muscles in rats, mediated by epigenetic DNA hypermethylation, enhancing resting pulmonary ventilation and predisposing to collapse of the upper airways in juvenile and adult life. Periods of apnoea, commonly observed in prematures and newborns, are an important risk factor for the development of cardiorespiratory diseases in adulthood. In the present study, we evaluated changes in pulmonary ventilation and respiratory motor pattern in juvenile and adult rats exposed to postnatal chronic intermittent hypoxia (pCIH). Newborn male Holtzman rats (P1) were submitted to pCIH (6% O2 for 30 s, every 9min, 8h a day (09.30-17.30 h)) during their first 10days of life, while control animals were maintained under normoxic conditions (20.8% O2 ). Thereafter, animals of both groups were maintained under normoxia until the experiments. Unanaesthetized juvenile pCIH rats (n=27) exhibited elevated tidal volume and respiratory irregularities (P<0.05) compared to control rats (n=7). Decerebrate, arterially perfused in situ preparations of juvenile pCIH rats (n=11) displayed augmented phrenic nerve (PN) burst amplitude and reduced central vagus nerve activity in comparison to controls (n=10). At adulthood, pCIH rats (n=5) showed enhanced tidal volume (P<0.05) and increased respiratory variability compared to the control group (n=5). The pCIH-induced changes in ventilation and respiratory motor outputs were prevented by treatment with the DNA methyltransferase inhibitor decitabine (1mgkg-1 , i.p.) during the exposure to pCIH. Our data demonstrate that pCIH in rats impacts, in a persistent way, control of the respiratory pattern, increasing PN activity to the diaphragm and reducing the vagal-related activity to laryngeal muscles, which, respectively, may contribute to improve resting pulmonary ventilation and predispose to collapse of the upper airways during quiet breathing.

Evaluation of Changes in Respiratory Patterns by Repeating under Different Respiratory Conditions

Evaluation of Changes in Respiratory Patterns by Repeating under Different Respiratory Conditions

Respiratory measurement using infrared thermography and respiratory volume monitor during sedation in patients undergoing endoscopic urologic procedures under spinal anesthesia.

We aimed to evaluate changes in respiratory pattern after sedation by simultaneously applying a respiratory volume monitor (ExSpiron1Xi, RVM) and infrared thermography (IRT) to patients undergoing spinal anesthesia during endoscopic urologic surgeries. After spinal anesthesia was performed, the patient was placed in a lithotomy position for surgery. Then, we established the baseline of the RVM, and started monitoring the mouth and nose with the infrared camera. SpO2 was continuously measured throughout these processes. Once the baseline was set, 0.05mg/kg midazolam was administered for sedation. Apnea was defined as cessation of airflow for ≥ 10s with respiratory rate of < 6 breaths/min; hypopnea was defined as a decrease in oxygen hemoglobin of > 4%, compared to baseline. We measured the time at which apnea was detected by IRT, the time at which hypopnea was detected by RVM, and the time at which hypoxia was detected by SpO2. Twenty patients (age: 68.9 ± 11.2years, body mass index: 24.2 ± 2.6kg/min2) completed the study. Before sedation, the baseline correlation coefficient of respiratory rate detection between RVM and IRT was 0.866. After midazolam administration, apnea was detected in all subjects within the first 5min by IRT; the median time required to detect apnea was 102.5 [interquartile range (IQR) 25-75%: 80-155]s. Hypopnea was detected in all subjects within the first 5min by RVM: the median time required to detect hypopnea was 142.5 (IQR 115-185.2)s. The median time required for SpO2 to decrease > 4% from baseline was 160 (IQR 125-205)s. Our results suggest that IRT can be useful for rapid detection of respiratory changes in patients undergoing sedation following spinal anesthesia for endoscopic urologic procedures.

The effect of DAMGO injections on the respiratory pattern varies between subareas of the ventral respiratory column in adult rabbits

We have previously described how sequential microinjections of high concentrations of the mu‐opioid agonist [D‐Ala2, N‐MePhe4, Gly‐ol]‐enkephalin (DAMGO) into the ventral respiratory column (VRC) depressed ventilation with rather variable changes in respiratory pattern in the adult, in vivo, decerebrate rabbit model (1). This study aimed to distinguish whether DAMGO injections into subareas of the VRC that were functionally identified by their differential respiratory pattern response to local microinjection of α‐Amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) resulted in different effects on the respiratory pattern. The study was approved by the local Animal Care Committee and conformed to NIH standards. Adult New Zealand White rabbits (3–4 kg) were anesthetized, tracheotomized, ventilated, decerebrated and vagotomized. Nerve activity was recorded from the c5 rootlet of the phrenic nerve, time averaged and used to calculate inspiratory and expiratory durations. Gridwise localized pressure injections of AMPA (50 μM, 70 nl) utilizing a multibarrel glass pipette with a tip diameter of 20μm into the VRC rostral of obex identified two areas with distinctly different pattern changes: An area (on average 2mm rostral from obex, 2.5mm lateral from midline, 4.5mm ventral to the dorsal surface) where AMPA injection caused significant tachycardia with decreased peak phrenic activity (PPA) and a second area (on average 1mm rostral, 2 mm lateral, 3.5mm ventral) where AMPA caused less tachycardia and an increase in PPA. In twelve animals, DAMGO injection (100μM, 700nl) into the more rostral area caused a decrease in inspiratory duration (from 1.2±0.1sec to 0.9±0.2sec, mean±SE) while injection into the more caudal area caused a small increase (from 1.3±0.1sec to 1.4±0.1sec). These effects were significantly different (p&lt;0.001, 2‐way ANOVA, factors: location, drug). DAMGO injection increased expiratory duration similarly in both areas (from 1.1±0.2 sec to 1.9±0.4sec and from 1.5±0.3sec to 2.2±0.3sec, difference between areas not significant). This resulted in no change in respiratory rate in the rostral area but a decrease in rate in the caudal area (from 25±3 bpm to 20±3bpm, difference between areas p&lt;0.001). PPA was similarly decreased in both areas (from 100% to 81±7% and from 100% to 95±2%, difference not significant). While the rostral area in location and AMPA response may match the preBötzinger area as described, e.g., by Marchenko (2), respiratory pattern can also be affected in more caudal subareas of the VRC. We suggest that glutamate agonists can elicit tachypnea in various subareas of the VRC and that injection of DAMGO into these individual subareas can have different effects on the respiratory pattern. This may be an explanation for diverging results of DAMGO injection between different studies using glutamate agonists for functional identification of their target.Support or Funding InformationNIH R01GM112960‐01A1 (Dr. Stucke) and VA merit grant I01BX000721 (Dr. Zuperku).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

OFFSPRING OF OBESE DAMS PRESENT CHANGES IN RESPIRATORY AND SYMPATHETIC ACTIVITIES

Obesity in dams is associated with the development of several pathologies in the offspring, including cardiovascular and hormonal dysfunctions. In this study, we investigated the pattern of respiratory and sympathetic activities in the offspring of dams treated with a high‐fat diet (HFD − 45% fat). Adult female Holtzman rats (250 g) were fed with standard diet (SD) or HFD during 6 weeks before, during gestation and lactation. After weaning, male offspring of SD dams (O‐SD) or HFD dams (O‐HFD) were fed with SD. At P28–32, O‐SD and O‐HFD rats were surgically prepared to obtain the arterially‐perfused in situ preparation to examine the thoracic sympathetic, phrenic, hypoglossal and abdominal activities under basal conditions and during peripheral chemoreceptors activation (KCN −0.05%). O‐HFD rats exhibited augmented baseline phrenic inspiratory (0.80 ± 0.04 vs O‐SD: 0.57 ± 0.07 s; n=6; p &lt; 0.05) and hypoglossal pre‐inspiratory times (0.60 ± 0.11 vs O‐SD: 0.27 ± 0.08 s, n=4; p &lt; 0.05) compared to O‐SD. Additional expiratory bursts were observed in baseline abdominal activity of O‐HFD group, indicating the presence of active expiration (8.5 ± 2.5 vs O‐SD: 1.3 ± 0.6 events/min, n = 4 p &lt; 0.05). Moreover, O‐HF rats showed weakened baseline respiratory‐related modulation of sympathetic activity compared to O‐HFD group. In response to stimulation of peripheral chemoreceptors, O‐HFD group showed greater abdominal reflex responses (212 ± 20 vs O‐SD: 134 ± 21 %; n = 4; p&lt;0.05), but no significant differences were noted in the others recorded nerves comparing to O‐SD. The results indicate that male offspring of HFD‐fed dams exhibit changes in baseline respiratory pattern associated with the presence of active expiration, and blunted respiratory‐sympathetic coupling. Part of these changes persist during peripheral chemoreceptor stimulation.Support or Funding InformationFAPESP (2016/23513‐1; 2013/17251‐6) and CNPq (425586/2016‐2).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Spontaneous breathing during veno-venous extracorporeal membrane oxygenation.

Veno-venous extracorporeal membrane oxygenation (VV ECMO) has started to be applied in awake spontaneously breathing patients as an alternative to invasive mechanical ventilation. As the physiologic cardiorespiratory variability is increased in this condition, the dynamic interaction between patient respiratory activity and extracorporeal system function affects the clinical management. The effect of extracorporeal CO2 removal on patient respiratory drive is variable and not always predictable, with some patients responding to CO2 removal with a decrease in respiratory rate and effort and other patients demonstrating a persistently high work of breathing independent on CO2 unload. While the pathophysiological mechanisms of this different interactions are still to be clarified, improved monitoring ability is needed both to titrate the support in responders and to avoid the risk of ventilation injury in non-responders. Acute changes in patient respiratory patterns may also occur during spontaneous breathing, making it difficult to maintain constant levels of extracorporeal respiratory support, also because changes in the distribution of venous blood volume due to lung-heart interactions affect extracorporeal blood flow. Assessment of native lung function and of its evolution over time is challenging while respiratory gas exchanges are provided by the extracorporeal system, since both oxygenation and decarboxylation capabilities can be fully evaluated only when alveolar ventilation is restored reducing extracorporeal CO2 removal. The rationale for using "awake ECMO" varies across different types of acute respiratory failure: the pathophysiological mechanisms of the underlying disease affect the patient-ECMO interaction and the goal of support. In this review we discuss the pathophysiology, technical challenges and monitoring issues of the use of ECMO in awake spontaneously breathing patients with acute respiratory failure of different etiologies.

Concurrent Respiratory Motion Correction of Abdominal PET and Dynamic Contrast-Enhanced-MRI Using a Compressed Sensing Approach.

We present an approach for concurrent reconstruction of respiratory motion-compensated abdominal dynamic contrast-enhanced (DCE)-MRI and PET data in an integrated PET/MR scanner. The MR and PET reconstructions share the same motion vector fields derived from radial MR data; the approach is robust to changes in respiratory pattern and does not increase the total acquisition time. Methods: PET and DCE-MRI data of 12 oncologic patients were simultaneously acquired for 6 min on an integrated PET/MR system after administration of 18F-FDG and gadoterate meglumine. Golden-angle radial MR data were continuously acquired simultaneously with PET data and sorted into multiple motion phases on the basis of a respiratory signal derived directly from the radial MR data. The resulting multidimensional dataset was reconstructed using a compressed sensing approach that exploits sparsity among respiratory phases. Motion vector fields obtained using the full 6-min (MC6-min) and only the last 1 min (MC1-min) of data were incorporated into the PET reconstruction to obtain motion-corrected PET images and in an MR iterative reconstruction algorithm to produce a series of motion-corrected DCE-MR images (moco_GRASP). The motion-correction methods (MC6-min and MC1-min) were evaluated by qualitative analysis of the MR images and quantitative analysis of SUVmax and SUVmean, contrast, signal-to-noise ratio (SNR), and lesion volume in the PET images. Results: Motion-corrected MC6-min PET images demonstrated 30%, 23%, 34%, and 18% increases in average SUVmax, SUVmean, contrast, and SNR and an average 40% reduction in lesion volume with respect to the non-motion-corrected PET images. The changes in these figures of merit were smaller but still substantial for the MC1-min protocol: 19%, 10%, 15%, and 9% increases in average SUVmax, SUVmean, contrast, and SNR; and a 28% reduction in lesion volume. Moco_GRASP images were deemed of acceptable or better diagnostic image quality with respect to conventional breath-hold Cartesian volumetric interpolated breath-hold examination acquisitions. Conclusion: We presented a method that allows the simultaneous acquisition of respiratory motion-corrected diagnostic quality DCE-MRI and quantitatively accurate PET data in an integrated PET/MR scanner with negligible prolongation in acquisition time compared with routine PET/DCE-MRI protocols.

The impact of breathing pattern and rate on inspiratory muscles activity.

Different rehabilitation programs are used to relieve dyspnea for hyper-inflated lung patients. In this study, a new approach, based on integrated changes in respiratory rate and pattern, for inspiratory muscles rehabilitation and training was examined utilizing noninvasive measurements of the two inspiratory muscles (rib cage inspiratory and neck inspiratory muscles) activity during controlled breathing in healthy subjects. Muscles activity was measured using electromyography, while subjects, breathed at different combinations of respiratory rate (6, 10, 16 breath per minutes) and inspiratory duty cycles (TI/Ttot). The results clearly show that both muscles were most active at the lowest evaluated respiratory rate, and that alteration of the duty cycle at the lowest rate significantly (p< 0.05) changes their electrical activity. Breathing at low respiratory rate RR is recommended for hyper-inflated lung patients in order to improve their gas exchange, therefore, it is recommended for these patients to find their most effective combination of RR and TI/Ttot and to use control breathing to practice their breath at optimum combination.