Ventilation Output Research Articles

On the optimization of the construction of ventilation systems during the construction of metro by underground method

The article discusses optimal versions for placement of ventilation systems for deep-laid underground lines, performed in a closed way, with the removal of the ventilation chamber from the ventilation output and placing it either in the ventilation shaft or in a specially constructed ventilation chamber located near the trunk, which significantly simplifies the design of excavation, and as a result, speed up its construction. To reduce the construction time, it is proposed to perform parallel work on the vent development and the ventilation chamber, including the possible installation of process equipment in parallel with the mining operations during the construction of the metro by the underground method.

Effects of a tunnel ventilation system within the tie-stall barn environment upon the productivity of dairy cattle during the winter season.

ObjectiveThe objective of this study was to examine the effect of using a tunnel ventilation system within the dairy barn environment upon the productivity of dairy cows during the winter season.MethodsThe study was performed at the University Farm, Faculty of Agriculture, Utsunomiya University. Twenty-one Holstein dairy cows (5 heifers and 16 multiparous) were enclosed in a stall barn. Unventilated (UV) and tunnel-ventilated (TV) was operated by turns every other week, and a number of key parameters were measured in the barn, including tunnel ventilation output, temperature, relative humidity, gas concentrations (oxygen [O2], carbon dioxide [CO2], and ammonia [NH3]). Also, skin and rectal temperature, respiratory rate, blood gas concentrations, and bacterial count were measured from nipple attachments on ten cows. The amount of fodder left uneaten, and general components and somatic cell count of the milk were measured.ResultsAs for our dairy barn environment, air temperature dropped significantly with the passage of time with TV. Humidity was significantly higher with TV at 0600 h compared to UV, while CO2 and NH3 concentrations with UV were significantly higher than with TV at 0000 h and 0600 h. Skin temperature was significantly lower with TV compared to UV at 0000 h and 0600 h. Respiratory rate was also significantly lower at 0600 h with TV than with UV. Bacterial count for the nipple attachments was significantly lower with TV than with UV at 0600 h. The amount of leftover fodder was significantly less with TV in comparison with UV.ConclusionOur results suggest that a TV system in the winter barn results in environmental improvements, such as reductions in unfavorable gas concentrations and bacterial growth. Consequently, it is expected that barns utilizing a TV system will be beneficial for both animal health and production.

Noradrenergic tuning, not simple rate effects, produces temperature‐sensitivity of the respiratory network in bullfrogs

Animals match ventilation to metabolic and acid‐base regulatory demands during changes in body temperature. Across vertebrates, ventilation increases at warmer temperatures and decreases at cooler temperatures. At the organismal level this is attributed to metabolic feedback and/or alpha‐stat pH regulation; however, the cellular mechanisms that produce ventilatory output in response to brain temperature changes remain unclear. To identity mechanisms underlying temperature‐sensitivity of the respiratory control network, we used brainstem‐spinal cord preparations producing spontaneously active, rhythmic motor output similar to breathing in vivo of adult bullfrogs Lithobates catesbeianus. In vitro brainstem‐spinal cords were superfused with artificial cerebrospinal fluid (aCSF) equilibrated at 90% O2, 1.3% CO2, and balance N2. Whole nerve recordings from the trigeminal (V) and vagus (X) nerves were used for measuring respiratory‐related activity. We applied temperature ramps from 20°C to 15°C and then to 25°C; each step lasted 15 minutes. Bursting frequency was analyzed for the last 5 minutes of each step and then normalized to percent of baseline (20°C). Consistent with in vivo and in vitro data (Bícego‐Nahas and Branco, 1999; Morales and Hedrick, 2002), we demonstrate that the frequency of respiratory‐related nerve activity is stable across high temperatures, but not lower temperatures (One‐way ANOVA p=0.0013; percent of baseline significantly lower at 15°C compared to 20°C and compared to 25°C, but no difference between 20°C and 25°C; Tukey's Multiple Comparison Test). The locus coeruleus (LC) is a nucleus of the respiratory network and is the main supplier of norepinephrine in the brain. LC neurons from bullfrogs are paradoxically activated by decreases in temperature (Santin et al., 2013) suggesting that firing frequencies inversely proportional to temperature may play a role in setting the respiratory frequency across temperatures. To identify the role of norepinephrine in generating the respiratory frequency, we applied the temperature protocol while blocking the main adrenergic receptors (AR). For blocking α1AR, preparations were superfused with aCSF containing Prazosin and for blocking α2AR we used RX821002. We found that bursting stability at high temperatures is disrupted when α1AR are blocked (One‐way ANOVA p=0.0011; percent of baseline significantly lower at 15°C compared to 20°C and 25°C, and percent of baseline significantly lower at 20°C compared to 25°C; Tukey's Multiple Comparison Test). In contrast, the inhibition of bursting frequency at 15°C was lost when α2AR were blocked (One‐way ANOVA p=0.1649; percent of baseline not different at 15°C, 20°C and 25°C). These results imply that norepinephrine tuning through different receptors, rather than simple Q10 effects, plays a major role in generating the breathing frequency across temperatures to match metabolic demands and acid‐base regulation requirements at those temperatures.Support or Funding InformationSupport for this project was provided by the Department of Biological Sciences at Wright State University as well as a Biology Award for Research Excellence and a Graduate Student Assembly Original Research Grant (both to M.V.).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Excitatory Modulation of the preBötzinger Complex Inspiratory Rhythm Generating Network by Endogenous Hydrogen Sulfide.

Hydrogen Sulfide (H2S) is one of three gasotransmitters that modulate excitability in the CNS. Global application of H2S donors or inhibitors of H2S synthesis to the respiratory network has suggested that inspiratory rhythm is modulated by exogenous and endogenous H2S. However, effects have been variable, which may reflect that the RTN/pFRG (retrotrapezoid nucleus, parafacial respiratory group) and the preBötzinger Complex (preBötC, critical for inspiratory rhythm generation) are differentially modulated by exogenous H2S. Importantly, site-specific modulation of respiratory nuclei by H2S means that targeted, rather than global, manipulation of respiratory nuclei is required to understand the role of H2S signaling in respiratory control. Thus, our aim was to test whether endogenous H2S, which is produced by cystathionine-β-synthase (CBS) in the CNS, acts specifically within the preBötC to modulate inspiratory activity under basal (in vitro/in vivo) and hypoxic conditions (in vivo). Inhibition of endogenous H2S production by bath application of the CBS inhibitor, aminooxyacetic acid (AOAA, 0.1–1.0 mM) to rhythmic brainstem spinal cord (BSSC) and medullary slice preparations from newborn rats, or local application of AOAA into the preBötC (slices only) caused a dose-dependent decrease in burst frequency. Unilateral injection of AOAA into the preBötC of anesthetized, paralyzed adult rats decreased basal inspiratory burst frequency, amplitude and ventilatory output. AOAA in vivo did not affect the initial hypoxia-induced (10% O2, 5 min) increase in ventilatory output, but enhanced the secondary hypoxic respiratory depression. These data suggest that the preBötC inspiratory network receives tonic excitatory modulation from the CBS-H2S system, and that endogenous H2S attenuates the secondary hypoxic respiratory depression.

Value of transesophageal echocardiography in estimating pulmonary arterial index and pulmonary vein index for guiding total correction of tetralogy of Fallot

Objective To investigate the value of transesophageal echocardiography (TEE) in estimating pulmonary arterial index (PAI) and pulmonary vein index (PVI) for guiding total correction of tetralogy of Fallot (TOF). Methods 80 patients with TOF were studied. TEE was used to measure the diameters of left and right pulmonary arteries and four pulmonary veins at pre-operation, PAI and PVI were calculated and analyzed statistically. Results There was significant correlation between PAI and PVI (r=0.853, P=0.000). Receiver operator characteristic curve (ROC curve) analysis showed that the area under the ROC curve of PAI and PVI in detecting prolonged stay in intensive care unit (ICU) after operation were 0.704, 0.781, the border value were 147.25, 286.42 mm2/m2, the sensitivity were 90%, 100%, and the specificity were 74%, 74%, respectively. The area under the ROC curve of PAI and PVI in detecting prolonged mechanical ventilation after operation were 0.817, 0.789, the border value were 152.48, 302.12 mm2/m2, the sensitivity were 90%, 90%, and the specificity were 75%, 77%, respectively. The area under the ROC curve of PAI and PVI in detecting low cardiac output syndrome after operation were 0.955, 0.926, the border value were 130.55, 209.09 mm2/m2, the sensitivity were 100%, 83%, and the specificity were 90%, 89%, respectively. Conclusion TEE can be used as a quantitative method to evaluate PAI and PVI in patients with TOF, there is significant correlation between the two indices, PAI and PVI carry higher sensitivity and specificity in detecting prolonged stay in ICU, prolonged mechanical ventilation and low cardiac output syndrome after operation. Key words: Transesophageal echocardiography; Tetralogy of Fallot; Pulmonary arterial index; Pulmonary vein index

Nursing Evaluation of Risk Factors Associated with Surgical Site Infection Among Coronary Artery Bypass Graft Patients at King Abdulaziz University Hospital

Surgical site infection is postoperative wound infection that occurs after surgery. The complications in the acute care facilities with up to 60% of surgical site infection cases estimated to be preventable by using evidence-based practice. Not with standing the advances in the coronary artery bypass graft, the rising prevalence of surgical site infection has become a primary concern in the infection control practices. The current study amid to evaluate the risk factors associated with the surgical site infections among coronary artery bypass graft patients and, to assess nurses compliance to bundle care to prevent surgical site infection. The study followed a quantitative, retrospective design and was carried out in King Abdulaziz University Hospital in Jeddah city. All sample (n= 120) coronary artery by-pass graft patient's record complied between January 2011 to December 2013. The study revealed statistically significant results between the preference of surgical site infection and demographic factor e.g. body mass index, patient risk factors such as diabetes type1 and 2, selected pre-operative factors e.g. Methicilin-resistant staphylococcus aurous, postoperative factors e.g. rewiring, dressing, ventilation and low cardiac output. This study established that the compliance with the bundle was proven to be effective in reducing risk factors to surgical site infection however nurses adherence to surgical site infection bundle care were incomplete and required more enforcement to comply. Based on the finding, the investigator recommended that nurses should be aware of the importance of adhering to surgical site infection bundles. Nurses should not only be educated on the importance of the bundles, but on how effectives apply the bundles at different stages.

An energy-efficient and environment-friendly method for normalizing the microclimate in heated mineshaft compartments

Underground mineshaft compartments with non-effective ventilation and heat output from mining facilities form an unfavourable microclimate that negatively affects the efficiency of work and the health of miners. Studies of the actual state of the microclimate conditions in the drainage units of the Kryvbas mines show that when two or three pumping units operate simultaneously, the air temperature in them reaches 36-38°C and the air velocity fluctuates within 0.2–0.3 m/s. Removal of warm air from the pumping unit is aggravated by lack of special ventilation openings and drop of pressure at the inlet and outlet of the unit. To solve the problem of normalizing the microclimate in underground mine compartments with operating facilities, we modelled mathematically the process of cooling with the help of a pneumatically-vortex device (PVD). The mathematical model describes changes in thermal and physical properties of the cooled air stream formed by the PVD as well as allows determining its basic parameters – long range x max =34.9 m and diameter 2r max =12.58 m – and studying the temperature field of the stream. We have used the mathematical modelling to develop a program of regulating the microclimate in underground mine compartments that are provided with heat sources. The model is coded in the programming language Visual Basic for Applications Microsoft Excel and has a simple interface. The use of this program allows adjusting the parameters of the microclimate in mineshaft compartments in two modes – Airing and Cooling – with an optimal use of the compressed air and ventilation air. The research findings presented in the article have been introduced in industrial conditions – in the pumping units of the Lenin Mine PJSC Kryvbaszalizrudkom and the Artem Mine PJSC ArselorMittal Kryvyi Rih (Ukraine).

Functional link between the hypocretin and serotonin systems in the neural control of breathing and central chemosensitivity.

Serotonin (5-HT)-synthesizing neurons of the medullary raphe are putative central chemoreceptors, proposed to be one of potentially multiple brain stem chemosensitive cell types and loci interacting to produce the respiratory chemoreflex. Hypocretin-synthesizing neurons of the lateral hypothalamus are important contributors to arousal state, thermoregulation, and feeding behavior and are also reportedly involved in the hypercapnic ventilatory response. Recently, a functional interaction was found between the hypocretin system and 5-HT neurons of the dorsal raphe. The validity and potential significance of hypocretin modulation of medullary raphe 5-HT neurons, however, is unknown. As such, the purpose of this study was to explore functional interactions between the hypocretin system and 5-HT system of the medullary raphe on baseline respiratory output and central chemosensitivity. To explore such interactions, we used the neonatal in vitro medullary slice preparation derived from wild-type (WT) mice (normal 5-HT function) and a knockout strain lacking all central 5-HT neurons (Lmx1b(f/f/p) mice). We examined effects of acidosis, hypocretin-1, a hypocretin receptor antagonist (SB-408124), and the effect of the antagonist on the response to acidosis. We confirmed the critical role of 5-HT neurons in central chemosensitivity given that the increased hypoglossal burst frequency with acidosis, characteristic of WT mice, was absent in preparations derived from Lmx1b(f/f/p) mice. We also found that hypocretin facilitated baseline neural ventilatory output in part through 5-HT neurons. Although the impact of hypocretin on 5-HT neuronal sensitivity to acidosis is still unclear, hypocretins did appear to mediate the burst duration response to acidosis via serotonergic mechanisms.

The Effects of Dietary Capsaicin on Ventilation in Aging Mice

Capsaicin (CAP), the main pungent component of chili peppers, is a selective agonist for transient receptor potential vanilloid 1 (TRPV1). Stimulation of TRPV1 receptors with low doses of CAP results in augmented ventilatory output in anesthetized mice (Wang, 2006 JAP). We tested the hypothesis that dietary intake of CAP in older mice would augment ventilation compared to a control diet. Male mice were tested using unrestrained barometric plethysmography to quantify ventilation before initiation of a specialized diet and after 4‐weeks of AIN‐93G diet (Harlan Teklad) enhanced with either CAP dissolved in lecithin (50 mg/kg food weight: CAP; n=13) or lecithin only (CON; n=12). Mice were acclimated to the chamber (30 min – 180 min) and a 10‐min baseline was collected with room air. Data were analyzed using a multi‐variate linear model and are presented as MEAN±SEM; p < 0.05. At 23‐mon, mice displayed a similar pattern of quiet breathing (data combined; Freq 124±4 bpm, tidal volume (TV) 0.33±0.01 mL/breath, minute ventilation (MV) 40.7±2.1 mL/min). Following 4 weeks of AIN‐93G diet, CON vs. CAP groups demonstrated no differences when exposed to room air for Freq (119±9 vs. 146±13 bpm), TV (0.34±0.02 vs. 0.32±0.01 mL/breath) or MV (39.3±2.6 vs. 47.1±4.7). These responses indicate that dietary CAP does not alter quiet breathing in aging mice. Both groups were exposed to acute hypoxia (15 minutes; 10% O2); these data may provide additional insight regarding the pattern of breathing following dietary CAP. Funding: LMC Student Research Committee; McDevitt Center Research Fellowships in Natural Science to AL and SR.

Cardiorespiratory alterations induced by low-intensity exercise performed in water or on land.

The aim of this study was to compare the cardiorespiratory alterations induced by a low-intensity exercise performed on land or in water. Sixteen healthy subjects were investigated. The exercise consisted of a 1-h period of ergocycling at 35%-40% of peak oxygen uptake. Investigations were performed at rest and 45 min after the beginning of the exercises. Hemodynamic changes were studied by Doppler-echocardiography. Gas exchanges were continuously monitored by an oxygen gas analyzer. Blood samples were taken successively at baseline, within the last minutes of the exercise bout, and during recovery to measure total protein concentration and natriuretic peptides. Cardiovascular parameters were not significantly different during exercise performed on land or in water. As a result of an accelerated breathing frequency, ventilation output was significantly greater in water. Biological changes included a decrease in total protein concentration and an increase in natriuretic peptides in water. During low-intensity exercise, ventilatory alterations favoured increasing the work of breathing while in the water when compared with the same exercise performed on land. Hemodynamic changes were similar in the 2 conditions. Furthermore, biological findings suggest that the fluid transfer from intravascular sector toward interstitial sector could be facilitated in water.

Automated weaning and SBT systems versus non-automated weaning strategies for weaning time in invasively ventilated critically ill adults.

Automated systems use closed-loop control to enable ventilators to perform basic and advanced functions while supporting respiration. SmartCare™ is a unique automated weaning system that measures selected respiratory variables, adapts ventilator output to individual patient needs by operationalizing predetermined algorithms and automatically conducts spontaneous breathing trials (SBTs) when predetermined thresholds are met. The primary objective of this review was to compare weaning time (time from randomization to extubation as defined by study authors) between invasively ventilated critically ill adults weaned by automated weaning and SBT systems versus non-automated weaning strategies.As secondary objectives, we ascertained differences between effects of alternative weaning strategies on clinical outcomes (time to successful extubation, time to first SBT and first successful SBT, mortality, ventilator-associated pneumonia, total duration of ventilation, lengths of intensive care unit (ICU) and hospital stay, use of non-invasive ventilation (NIV), adverse events and clinician acceptance).The third objective of our review was to use subgroup analyses to explore variations in weaning time, length of ICU stay, mortality, ventilator-associated pneumonia, use of NIV and reintubation according to (1) the type of clinician primarily involved in implementing the automated weaning and SBT strategy, (2) the ICU (as a reflection of the population involved) and (3) the non-automated (control) weaning strategy utilized.We conducted a sensitivity analysis to evaluate variations in weaning time based on (4) the methodological quality (low or unclear versus high risk of bias) of the included studies. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 5; MEDLINE (1966 to 31 May 2013); EMBASE (1988 to 31 May 2013); the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 31 May 2013), Evidence-Based Medicine Reviews and Ovid HealthSTAR (1999 to 31 May 2013), as well as conference proceedings and trial registration websites; we also contacted study authors and content experts to identify potentially eligible trials. Randomized and quasi-randomized trials comparing automated weaning and SBT systems versus non-automated weaning strategies in intubated adults. Two review authors independently assessed trial quality and abstracted data according to prespecified criteria. Sensitivity and subgroup analyses were planned to assess the impact on selected outcomes of the following: (1) the type of clinician primarily involved in implementing automated weaning and SBT systems, (2) the ICU (as a reflection of the population involved) and (3) the non-automated (control) weaning strategy utilized. We pooled summary estimates from 10 trials evaluating SmartCare™ involving 654 participants. Overall, eight trials were judged to be at low or unclear risk of bias, and two trials were judged to be at high risk of bias. Compared with non-automated strategies, SmartCare™ decreased weaning time (mean difference (MD) -2.68 days, 95% confidence interval (CI) -3.99 to -1.37; P value < 0.0001, seven trials, 495 participants, moderate-quality evidence), time to successful extubation (MD -0.99 days, 95% CI -1.89 to -0.09; P value 0.03, seven trials, 516 participants, low-quality evidence), length of ICU stay (MD -5.70 days, 95% CI -10.54 to -0.85; P value 0.02, six trials, 499 participants, moderate-quality evidence) and proportions of participants receiving ventilation for longer than seven and 21 days (risk ratio (RR) 0.44, 95% CI 0.23 to 0.85; P value 0.01 and RR 0.39, 95% CI 0.18 to 0.86; P value 0.02). SmartCare™ reduced the total duration of ventilation (MD -1.68 days, 95% CI -3.33 to -0.03; P value 0.05, seven trials, 521 participants, low-quality evidence) and the number of participants receiving ventilation for longer than 14 days (RR 0.61, 95% CI 0.37 to 1.00; P value 0.05); however the estimated effects were imprecise. SmartCare™ had no effect on time to first successful SBT, mortality or adverse events, specifically reintubation. Subgroup analysis suggested that trials with protocolized (versus non-protocolized) control weaning strategies reported significantly shorter ICU stays. Sensitivity analysis excluded two trials with high risk of bias and supported a trend toward significant reductions in weaning time favouring SmartCare™. Compared with non-automated weaning strategies, weaning with SmartCare™ significantly decreased weaning time, time to successful extubation, ICU stay and proportions of patients receiving ventilation for longer than seven days and 21 days. It also showed a favourable trend toward fewer patients receiving ventilation for longer than 14 days; however the estimated effect was imprecise. Summary estimates from our review suggest that these benefits may be achieved without increasing the risk of adverse events, especially reintubation; however, the quality of the evidence ranged from low to moderate, and evidence was derived from 10 small randomized controlled trials.

Automated weaning and spontaneous breathing trial systems versus non-automated weaning strategies for discontinuation time in invasively ventilated postoperative adults.

Automated systems use closed-loop control to enable ventilators to perform basic and advanced functions while supporting respiration. Selected automated systems can now not only measure selected respiratory variables and adapt ventilator output to individual patient needs by operationalizing predetermined algorithms but also automate the conduct of spontaneous breathing trials (SBTs). To summarize the evidence comparing automated weaning and SBT systems to non-automated mechanical ventilation strategies on time to mechanical ventilation discontinuation in adult postoperative patients. In secondary objectives we ascertained differences between automated weaning and SBT systems and non-automated mechanical ventilation discontinuation strategies on clinical outcomes (time to successful extubation, time to first SBT and first successful SBT, mortality, total duration of ventilation, intensive care unit (ICU) and hospital lengths of stay, use of non-invasive ventilation (NIV) following extubation, and adverse events). We searched CENTRAL (The Cochrane Library 2013, Issue 5); MEDLINE (OvidSP) (1966 to May 2013); EMBASE (OvidSP) (1988 to May 2013); CINAHL (EBSCOhost) (1982 to May 2013), Evidence Based Medicine Reviews and Ovid Health Star (1999 to May 2013), conference proceedings, trial registration websites, and contacted authors and content experts to identify potentially eligible trials. Randomized and quasi-randomized trials comparing automated weaning and SBT systems to non-automated mechanical ventilation discontinuation strategies in intubated adults in the postoperative setting. Two review authors independently assessed trial quality and abstracted data according to prespecified criteria. Sensitivity and subgroup analyses were planned to assess the impact of the type of (i) clinician primarily involved in implementing the automated weaning and SBT systems, (ii) intensive care unit (ICU), and (iii) non-automated discontinuation (control) strategy utilized on selected outcomes. We identified one randomized controlled trial of high quality, involving 300 patients , comparing SmartCare™ to a written protocol. In this trial, SmartCare™ had no effect on discontinuation time. While SmartCare™ significantly reduced the time to the first SBT (mean difference (MD) -0.34 days, 95% CI -0.60 to -0.08; P = 0.01) it did not reduce the time to the first successful SBT (MD -0.25 days, 95% CI -0.55 to 0.05; P = 0.10) and other clinically important outcomes. SmartCare™ did not demonstrate beneficial effects on most clinically important outcomes including time to successful extubation, total duration of mechanical ventilation, ICU and hospital lengths of stay, and the requirement for tracheostomy. Moreover, SmartCare™ did not favourably impact reintubation, mortality, self-extubation, and the proportion of patients undergoing protracted mechanical ventilation, with a small numbers of events in this single trial. There is a paucity of evidence from randomized controlled trials to support or refute use of automated weaning and SBT systems in discontinuing invasive mechanical ventilation in adult postoperative patients. In a single large trial of high methodologic quality, while the use of SmartCare™ to adjust ventilator settings and conduct SBTs shortened the time to undergoing the first SBT, it did not reduce the time to the first successful SBT or the rate of tracheostomy compared to a written protocol implemented by physicians. SmartCare™ did not demonstrate beneficial effects on clinically important outcomes including time to mechanical ventilation discontinuation, time to successful discontinuation, total duration of mechanical ventilation, and ICU and hospital lengths of stay. Additional well-designed, adequately powered randomized controlled trials are needed to clarify the role for SmartCare™ on important outcomes in patients who predominantly require short term ventilation and in specific postoperative patient populations.

Oxygen and ventilatory output during several activities of daily living performed by COPD patients stratified according to disease severity.

ObjectivesTo measure the oxygen and ventilatory output across all COPD stages performing 18 common ADL and identify the activities that present the highest metabolic and ventilatory output as well as to compare the energy expenditure within each disease severity. Materials and MethodsMetabolic (VO2 and VCO2), ventilatory (f and VE), cardiovascular (HR) and dyspnea (Borg score) variables were assessed in one hundred COPD patients during the completion of eighteen ADL grouped into four activities domains: rest, personal care, labor activities and efforts. ResultsThe activities with the highest proportional metabolic and ventilatory output (VO2/VO2max and VE/MVV) were walking with 2.5 Kg in each hand and walking with 5.0 Kg in one hand. Very severe patients presented the highest metabolic, ventilatory output and dyspnea than mild patients (p<0.05). ConclusionsCOPD patients present an increased proportion of energy expenditure while performing activities of daily living. The activities that developed the highest metabolic and ventilatory output are the ones associated to upper and lower limbs movements combined. Very severe patients present the highest proportional estimated metabolic and ventilatory output and dyspnea. Activities of daily living are mainly limited by COPD’s reduced ventilatory reserve.

The impact of aerosolized mucolytic agents on the airflow resistance of bacterial filters used in mechanical ventilation

In order to reduce the contamination in the ventilator, bacterial filters were placed on the expiratory limb of a ventilator circuit. Aerosolized mucolytic agents may increase the resistance of the ventilator. The goal of this study is to determine the impact of aerosolized mucolytic agents on the pressure change during mechanical ventilation. A lung model was investigated with mucolytic inhaled agents of 10% acetylcysteine and 2% hypertonic saline. The agents were administered using a jet nebulizer every 45 minutes for 15 minutes. The pressure drop was measured after nebulization. The end point was referred to the 45(th) dose or obstruction of the filter. Furthermore, the pressure drop after steam autoclaving was also measured. The maximum pressure was significantly higher with 10% acetylcysteine than with 2% sodium chloride (39.32 ± 7.22 cmH2O vs. 3.53 ± 0.90 cmH2O, p < 0.001). With acetylcysteine filters, the pressure drop over 4 cmH2O occurred earlier and had a good relationship between the degree of pressure drop and doses. The acetylcysteine group yielded a significant difference in the pressure drop compared to the newly autoclaved and the end point of inhalation (p = 0.043). This study demonstrated the aerosolized mucolytic agents could increase the pressure drop of the bacterial filters during mechanical ventilation. The pressure drop of the bacterial filters was higher with 10% acetylcysteine. It is critical to continuously monitor the expiration resistance, auto-positive end-expiratory pressure, and ventilator output waveform when aerosolized 10% acetylcysteine was used in mechanical ventilation patients.

Early Echocardiographic Outcomes in Mitral Valve Repair for Myxomatous Mitral Regurgitation – A Single Centre Experience

creatinine were associated with longer hours (>24 h) of mechanical ventilation, ICU stay and low cardiac output syndrome compared to the other groups. Group >100% rise of serum creatinine were associated with significant increase stroke (AdjustedHR 5.40 and 95%CI (1.90–15.34), multiorgan failure with adjusted HR 6.33and 95% CI (2.43–16.49). Increase of perioperative serum creatinine above 50% give higher chance to have postoperative renal failure adjusted HR 8.98 and 95% CI (3.96–20.37) increase to Adjusted HR 35.32 and 95% CI (16.79–74.31) in >100% group. Analysis of serum creatinine change showed that a 47% increase was the best predictor of renal failure after cardiac surgery, with 86.76% specificity and 64.89% sensitivity. Conclusions: An increase of perioperative serum creatinine in cardiac surgery was consistently associated with higher postoperative mortality and increase risk of most majormorbidityoutcomes.Efforts to identifypatientswith high risk of impaired renal function and preserve renal function before andduring cardiac surgerymay yield benefits for patients in the future. http://dx.doi.org/10.1016/j.hlc.2013.03.027 2012 Poster Presentation/Panel 2 Early EchocardiographicOutcomes inMitral ValveRepair for Myxomatous Mitral Regurgitation – A Single Centre

Advanced Ventilator Modes and Techniques

In addition to improving gas exchange by mechanical ventilation, minimizing iatrogenic lung injury and making the patient comfortable are important goals. This article reviews advanced ventilator modes and techniques that might help to accomplish these goals. Small tidal volumes (VT) and low ventilation pressure minimize ventilator-induced lung injury. Airway pressure release ventilation and high-frequency oscillatory ventilation may provide lung-protective ventilation in certain patients with refractory hypoxemia. Adaptive support ventilation (ASV) automatically adjusts VT and rate on the basis of the patient's respiratory mechanics to provide "safe" settings. When ventilator output does not match patient respiratory center timing, patient-ventilator asynchrony occurs. Proportional assist ventilation and neutrally adjusted ventilatory assist are unique modes of ventilation that provide ventilatory support in direct proportion to patient effort and therefore may be able to better match patient need and improve comfort. Weaning protocols reduce duration of ventilation and intensive care unit stay. Certain ventilator modes purport to automate part of the ventilator discontinuance process. The ASV progressively reduces support as the patient's lung condition improves, while SmartCare/pressure support (Dräger, Lübeck, Germany) reduces support and then initiates a spontaneous breathing trial. Further research is required to determine the proper place these new modes have in the intensive care unit.

Brain neuropeptides in central ventilatory and cardiovascular regulation in trout

Many neuropeptides and their G-protein coupled receptors (GPCRs) are present within the brain area involved in ventilatory and cardiovascular regulation but only a few mammalian studies have focused on the integrative physiological actions of neuropeptides on these vital cardio-respiratory regulations. Because both the central neuroanatomical substrates that govern motor ventilatory and cardiovascular output and the primary sequence of regulatory peptides and their receptors have been mostly conserved through evolution, we have developed a trout model to study the central action of native neuropeptides on cardio-ventilatory regulation. In the present review, we summarize the most recent results obtained using this non-mammalian model with a focus on PACAP, VIP, tachykinins, CRF, urotensin-1, CGRP, angiotensin-related peptides, urotensin-II, NPY, and PYY. We propose hypotheses regarding the physiological relevance of the results obtained.

Effects of dead space loading on neuro-muscular and neuro-ventilatory coupling of the respiratory system during exercise in healthy adults: Implications for dyspnea and exercise tolerance

We examined the effects of dead space loading (DSL) on ventilation (V˙E), neural respiratory drive (EMGdi%max, diaphragm EMG expressed as a % of maximal EMGdi), contractile respiratory muscle effort (Pes,tidal%P(Imax), tidal esophageal pressure swing expressed as a % of maximal inspiratory Pes) and exertional dyspnea intensity ratings in 11 healthy adults with normal spirometry. Subjects completed, in random order, symptom-limited incremental cycle exercise tests under control (CTRL) and DSL (500 ml) conditions. Compared with CTRL, DSL decreased exercise tolerance by 20-25%; increased exertional dyspnea intensity ratings in direct proportion to concurrent increases in EMGdi%max, Pes,tidal%P(Imax) and V˙E; and had little/no effect on the inter-relationships between EMGdi%max, Pes,tidal%P(Imax) and V˙E during exercise. In conclusion, DSL was associated with an earlier onset of intolerable dyspnea; however, neuro-muscular and neuro-ventilatory coupling of the respiratory system remained relatively preserved during exercise in the presence of an increased external dead space. Under these circumstances, DSL-induced increases in exertional dyspnea intensity ratings reflected, at least in part, the awareness of increased neural respiratory drive, contractile respiratory muscle effort and ventilatory output.

Stabilizing Ventilation in OSAHS with CPAP Emergent Periodic Breathing Through the Use of Dead Space

Stabilizing Ventilation in OSAHS with CPAP Emergent Periodic Breathing Through the Use of Dead Space

Transgenic Mice Lacking Serotonin Neurons Have Severe Apnea and High Mortality during Development

Central serotonin (5-HT) neurons modulate many vital brain functions, including respiratory control. Whether breathing depends critically on 5-HT neurons, or whether their influence is excitatory or inhibitory, remains controversial. Here we show that neonatal Lmx1b(flox/flox;ePet-Cre/+) mice (also called Lmx1b(f/f/p) mice), which selectively lack serotonin neurons, display frequent and severe apnea lasting as long as 55 s. This was associated with a marked decrease in ventilation to less than one-half of normal. These respiratory abnormalities were most severe during the postnatal period, markedly improving by the time the pups were 2-4 weeks old. Despite the severe breathing dysfunction, many of these mice survived, but there was a high perinatal mortality, and those that survived had a decrease in growth rate until the age at which the respiratory defects resolved. Consistent with these in vivo observations, respiratory output was markedly reduced in isolated brainstem-spinal cord preparations from neonatal Lmx1b(f/f/p) mice and completely blocked in perfused brain preparations from neonatal rats treated with selective antagonists of 5-HT(2A) and neurokinin 1 (NK-1) receptors. The ventilatory deficits in neonatal Lmx1b(f/f/p) mice were reversed in vitro and in vivo with agonists of 5-HT(2A) and/or NK-1 receptors. These results demonstrate that ventilatory output in the neonatal period is critically dependent on serotonin neurons, which provide excitatory drive to the respiratory network via 5-HT(2A) and NK-1 receptor activation. These findings provide insight into the mechanisms of sudden infant death syndrome, which has been associated with abnormalities of 5-HT neurons and of cardiorespiratory control.