Patient–Ventilator Dyssynchrony in Critically Ill Patients

Patient–ventilator dyssynchrony is a mismatch between the patient’s respiratory efforts and mechanical ventilator delivery. Dyssynchrony can occur at any phase throughout the respiratory cycle. There are different types of dyssynchrony with different mechanisms and different potential management: trigger dyssynchrony (ineffective efforts, autotriggering, and double triggering); flow dyssynchrony, which happens during the inspiratory phase; and cycling dyssynchrony (premature cycling and delayed cycling). Dyssynchrony has been associated with patient outcomes. Thus, it is important to recognize and address these dyssynchronies at the bedside. Patient–ventilator dyssynchrony can be detected by carefully scrutinizing the airway pressure–time and flow–time waveforms displayed on the ventilator screens along with assessing the patient’s comfort. Clinicians need to know how to depict these dyssynchronies at the bedside. This review aims to define the different types of dyssynchrony and then discuss the evidence for their relationship with patient outcomes and address their potential management.

Colonial Agricultural Development Schemes

The period from the 1920s to the end of colonial rule saw increasing government intervention in agricultural production and the adoption of ambitious agricultural development schemes. These development schemes often aimed to increase and control the production and marketing of cash crops such as cotton and peanuts, essential to European industries. Examples include the Gezira Scheme (Sudan), the Office du Niger (French Soudan), the Tanganyika Groundnut Scheme, the Compagnie Générale des Oléagineux Tropicaux (CGOT, Senegal), as well as a host of other schemes. Confident in their agricultural expertise, colonial planners often sought radical transformations in African agricultural systems, away from extensive hoe cultivation toward intensive plow agriculture following a strict crop rotation. Worries about environmental degradation and population growth, as well as the need to manage social dislocation and maintain political stability, framed colonial strategies. Encountering African farmers with priorities and practices that were often at odds with their own, colonial planners failed to transform agriculture in the ways they intended. Nonetheless, development still wrought significant change as farmers considered whether to circumvent, resist, adapt, or adopt new technologies and farming methods. If at first agricultural development schemes were localized and mostly ineffective efforts to make empire profitable, by the 1940s and 1950s, agricultural development interventions became more widespread and intrusive. This helped generate rural support for anticolonial movements. Nonetheless, by the last decades of colonial rule, the idea of planned development as desirable became commonplace, not just within colonial governments, but also in international institutions and among nationalist leaders. Thus, state-led agricultural development would remain a powerful force in independent Africa.

Automated detection and quantification of reverse triggering effort under mechanical ventilation

Background Reverse triggering (RT) is a dyssynchrony defined by a respiratory muscle contraction following a passive mechanical insufflation. It is potentially harmful for the lung and the diaphragm, but its detection is challenging. Magnitude of effort generated by RT is currently unknown. Our objective was to validate supervised methods for automatic detection of RT using only airway pressure (Paw) and flow. A secondary objective was to describe the magnitude of the efforts generated during RT. Methods We developed algorithms for detection of RT using Paw and flow waveforms. Experts having Paw, flow and esophageal pressure (Pes) assessed automatic detection accuracy by comparison against visual assessment. Muscular pressure (Pmus) was measured from Pes during RT, triggered breaths and ineffective efforts. Results Tracings from 20 hypoxemic patients were used (mean age 65 ± 12 years, 65% male, ICU survival 75%). RT was present in 24% of the breaths ranging from 0 (patients paralyzed or in pressure support ventilation) to 93.3%. Automatic detection accuracy was 95.5%: sensitivity 83.1%, specificity 99.4%, positive predictive value 97.6%, negative predictive value 95.0% and kappa index of 0.87. Pmus of RT ranged from 1.3 to 36.8 cmH20, with a median of 8.7 cmH20. RT with breath stacking had the highest levels of Pmus, and RTs with no breath stacking were of similar magnitude than pressure support breaths. Conclusion An automated detection tool using airway pressure and flow can diagnose reverse triggering with excellent accuracy. RT generates a median Pmus of 9 cmH2O with important variability between and within patients. Trial registration BEARDS, NCT03447288.

Effect of nocturnal EPAP titration to abolish tidal expiratory flow limitation in COPD patients with chronic hypercapnia: a randomized, cross-over pilot study

Background Tidal expiratory flow limitation (EFLT) promotes intrinsic PEEP (PEEPi) in patients with chronic obstructive pulmonary disease (COPD). Applying non-invasive ventilation (NIV) with an expiratory positive airway pressure (EPAP) matching PEEPi improves gas exchange, reduces work of breathing and ineffective efforts. We aimed to evaluate the effects of a novel NIV mode that continuously adjusts EPAP to the minimum level that abolishes EFLT. Methods This prospective, cross-over, open-label study randomized patients to one night of fixed-EPAP and one night of EFLT-abolishing-EPAP. The primary outcome was transcutaneous carbon dioxide pressure (PtcCO2). Secondary outcomes were: peripheral oxygen saturation (SpO2), frequency of ineffective efforts, breathing patterns and oscillatory mechanics. Results We screened 36 patients and included 12 in the analysis (age 72 ± 8 years, FEV1 38 ± 14%Pred). The median EPAP did not differ between the EFLT-abolishing-EPAP and the fixed-EPAP night (median (IQR) = 7.0 (6.0, 8.8) cmH2O during night vs 7.5 (6.5, 10.5) cmH2O, p = 0.365). We found no differences in mean PtcCO2 (44.9 (41.6, 57.2) mmHg vs 54.5 (51.1, 59.0), p = 0.365), the percentage of night time with PtcCO2 > 45 mm Hg was lower (62(8,100)% vs 98(94,100)%, p = 0.031) and ineffective efforts were fewer (126(93,205) vs 261(205,351) events/hour, p = 0.003) during the EFLT-abolishing-EPAP than during the fixed-EPAP night. We found no differences in oxygen saturation and lung mechanics between nights. Conclusion An adaptive ventilation mode targeted to abolish EFLT has the potential to reduce hypercapnia and ineffective efforts in stable COPD patients receiving nocturnal NIV. Trial registration: ClicalTrials.gov, NCT04497090. Registered 29 July 2020—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04497090.

Noninvasive Neurally Adjusted Ventilator Assist Ventilation in the Postoperative Period Produces Better Patient-Ventilator Synchrony but Not Comfort

Background. Noninvasive neurally adjusted ventilatory assist (NAVA) has been shown to improve patient-ventilator interaction in many settings. There is still scarce data with regard to postoperative patients indicated for noninvasive ventilation (NIV) which this study elates. The purpose of this trial was to evaluate postoperative patients for synchrony and comfort in noninvasive pressure support ventilation (NIV-PSV) vs. NIV-NAVA. Methods. Twenty-two subjects received either NIV-NAVA or NIV-PSV in an object-blind, prospective, randomized, crossover fashion (observational trial). We evaluated blood gases and ventilator tracings throughout as well as comfort of ventilation at the end of each ventilation phase. Results. There was an effective reduction in ventilator delays (p<0.001) and negative pressure duration in NIV-NAVA as compared to NIV-PSV (p<0.001). Although we used optimized settings in NIV-PSV, explaining the overall low incidence of asynchrony, NIV-NAVA led to reductions in the NeuroSync-index (p<0.001) and all types of asynchrony except for double triggering that was significantly more frequent in NIV-NAVA vs. NIV-PSV (p=0.02); ineffective efforts were reduced to zero by use of NIV-NAVA. In our population of previously lung-healthy subjects, we did not find differences in blood gases and patient comfort between the two modes. Conclusion. In the postoperative setting, NIV-NAVA is well suitable for use and effective in reducing asynchronies as well as a surrogate for work of breathing. Although increased synchrony was not transferred into an increased comfort, there was an advantage with regard to patient-ventilator interaction. The trial was registered at the German clinical Trials Register (DRKS no.: DRKS00005408).

NIV Is not Adequate for High Intensity Endurance Exercise in COPD

Noninvasive ventilation (NIV) during exercise has been suggested to sustain higher training intensity but the type of NIV interface, patient-ventilator asynchronies (PVA) or technological limitation of the ventilator may interfere with exercise. We assessed whether these parameters affect endurance exercise capacity in severe COPD patients. In total, 21 patients with severe COPD not eligible to home NIV performed three constant workload tests. The first test was carried out on spontaneous breathing (SB) and the following ones with NIV and a nasal or oronasal mask in a randomized order. PVA and indicators of ventilator performance were assessed through a comprehensive analysis of the flow pressure tracing raw data from the ventilator. The time limit was significantly reduced with both masks (406 s (197–666), 240 s (131–385) and 189 s (115–545), p < 0.01 for tests in SB, with oronasal and nasal mask, respectively). There were few PVA with an oronasal mask (median: 3.4% (1.7–5.2)) but the ventilator reached its maximal generating capacity (median flowmax: 208.0 L/s (189.5–224.8) while inspiratory pressure dropped throughout exercise (from 10.1 (9.4–11.4) to 8.8 cmH2O (8.6–10.8), p < 0.01). PVA were more frequent with nasal mask (median: 12.8% (3.2–31.6), p < 0.01). Particularly, the proportion of patients with ineffective efforts > 10% was significantly higher with nasal interface (0% versus 33.3%, p < 0.01). NIV did not effectively improve endurance capacity in COPD patients not acclimated to home NIV. This was due to a technological limitation of the ventilator for the oronasal mask and the consequence either of an insufficient pressure support or a technological limitation for the nasal mask.

Conflicts of Interest in Human Subject Research: The Insufficiency of U.S. and International Standards

Researchers, as well as individuals and institutions that oversee their conduct, sometimes have conflicts of interest that weaken or render ineffective efforts to protect human research subjects. This article analyzes United States and international standards used to address conflicts of interest and reviews evidence regarding compliance. It finds current standards are insufficient and recommends that the federal government and international organizations adopt stronger legal standards that require resolving most significant conflicts of interest and specifying how to manage conflicts of interest not resolved.

"GAS WARS" OF THE RUSSIAN FEDERATION AND UKRAINE IN 2006 AND 2009: VISIONS OF UKRAINIAN SOCIAL AND POLITICAL OPINION

The article is specifically concerned with the visions of Ukrainian socio-political opinion on the gas wars of 2006 and 2009 that had emerged between the Russian Federation (RF) and Ukraine. The author investigated the approaches of representatives of the political, media, expert circles to provide an overview of this issue, as well as the results of sociological monitoring, which generally reflect the estimates of the average population. It has been argued that starting with a seemingly purely economic proposal to raise gas prices for Ukraine to a market level, Russia actually had a political goal - to punish Kyiv for delaying negotiations on the creation of a consortium with the Russians for the development of the Ukrainian gas transportation system and the pro-European course launched by the «orange team» and to discredit the Ukrainian side as a transit country to attract the attention of Europeans to several Russian gas pipeline construction projects to bypass Ukraine, which would become an alternative or even a replacement for the Ukrainian one. The results of the study suggest that, although the gas wars of 2006 and 2009 demonstrated the readiness of the Russian Federation to use its energy resources to achieve geopolitical aims, in Ukraine, this crisis was partly considered in the context of internal political struggle. Despite the judgment of Russia's non-market actions and the beginning of diversification of the Ukrainian energy system, mostly public discussion was unfolded around criticism, foremost, of the Ukrainian authorities, whose ineffective efforts, they say, were used by Russian Federation. Paradoxically, even the average population was to blame for the fuel crisis, if not exclusively official Kyiv, then both sides, rarely - only Russia. Keywords: "gas wars" 2006 and 2009, Ukrainian socio-political thought, Russian Federation, Ukraine.