Spontaneous Breathing Patients Research Articles

Development of a machine learning model for prediction of the duration of unassisted spontaneous breathing in patients during prolonged weaning from mechanical ventilation

PurposeTreatment of patients undergoing prolonged weaning from mechanical ventilation includes repeated spontaneous breathing trials (SBTs) without respiratory support, whose duration must be balanced critically to prevent over- and underload of respiratory musculature. This study aimed to develop a machine learning model to predict the duration of unassisted spontaneous breathing. Materials and methodsStructured clinical data of patients from a specialized weaning unit were used to develop (1) a classifier model to qualitatively predict an increase of duration, (2) a regressor model to quantitatively predict the precise duration of SBTs on the next day, and (3) the duration difference between the current and following day. 61 features, known to influence weaning, were included into a Histogram-based gradient boosting model. The models were trained and evaluated using separated data sets. Results18.948 patient-days from 1018 individual patients were included. The classifier model yielded an ROC-AUC of 0.713. The regressor models displayed a mean absolute error of 2:50 h for prediction of absolute durations and 2:47 h for day-to-day difference. ConclusionsThe developed machine learning model showed informed results when predicting the spontaneous breathing capacity of a patient in prolonged weaning, however lacking prognostic quality required for direct translation to clinical use.

Performances and limits of Bag-Valve-Device for pre-oxygenation and manual ventilation: A comparative bench and cadaver study

IntroductionBag-Valve-Device (BVD) is the most frequently used device for pre-oxygenation and ventilation during cardiopulmonary resuscitation (CPR). A minimal expired fraction of oxygen (FeO2) above 0.85 is recommended during pre-oxygenation while insufflated volume (VTi) should be reduced during manual ventilation. The objective was to compare the performances of different BVD in simulated conditions. MethodsNine BVD were evaluated during pre-oxygenation: spontaneous breathing patients were simulated on a test lung (mild and severe conditions). FeO2 was measured with and without positive end-expiratory pressure (PEEP). CO2 rebreathing was evaluated. Then, manual ventilation was performed by 36 caregivers (n = 36) from three hospitals on a specific manikin; same procedure was repeated by 3 caregivers (n = 3) on two human cadavers with three of the nine BVD: In non-CPR scenario and during mechanical CPR with Interrupted Chest Compressions strategy (30:2). ResultsPre-oxygenation: FeO2 was lower than 0.85 for three BVD in severe condition and for two BVD in mild condition. FeO2 was higher than 0.85 in eight of nine BVD with an additional PEEP valve (PEEP 5 cmH2O). One BVD induced CO2 rebreathing.Manual ventilation: For non-CPR manual ventilation, mean VTi was within the predefined lung protective range (4–8 mL/kg PBW) for all BVD on the bench. For CPR manual ventilation, mean VTi was above the range for three BVD on the bench. Similar results were observed on cadavers. ConclusionsSeveral BVD did not reach the FeO2 required during pre-oxygenation. Manual ventilation was significantly less protective in three BVD. These observations are related to the different BVD working principles.

Effect of sugammadex on postoperative nausea and vomiting after surgery for intracranial aneurysm

Objective: To investigate the effect of sugammadex on postoperative nausea and vomiting(PONV) after intracranial aneurysm surgery. Methods: Data from intracranial aneurysms patients who met the inclusion and exclusion criteria and underwent interventional surgery in the Department of Neurosurgery, Peking University International Hospital from January 2020 to March 2021 were prospectively included. According to the random number table method, the patients were divided by 1∶1 into the neostigmine+atropine group (group N) and the sugammadex group (group S). Use an acceleration muscle relaxation monitor for muscle relaxation monitoring, and administer neostigmine+atropine and sugammadex to block residual muscle relaxation drugs after surgery. The incidence rates of PONV and severity, the appearance of anesthesia, and the correlation between PONV and postoperative complications were recorded in both groups during five periods after surgery: 0-0.5 hours (T1),>0.5-2.0 hours(T2),>2.0-6.0 hours (T3),>6.0-12.0 hours (T4) and >12.0-24.0 hours (T5). Group comparisons of quantitative data were performed by the independent sample t-test, and categorical data was performed by the χ2 or rank sum test. Results: A total of 66 patients were included in the study, including 37 males and 29 female, aged (59.3±15.4) years (range: 18 to 77 years). The incidence rates of PONV of 33 patients in group S at different time periods of T1, T2, T3, T4, and T5 after surgery were respectively 27.3%(9/33),30.3%(10/33),12.1%(4/33),3.0%(1/33),0(0/33),and the incidence rates of PONV of 33 patients in the group N at different time periods of T1, T2, T3, T4 and T5 after surgery were respectively 36.4%(12/33),36.4%(12/33),33.3%(11/33),6.1%(2/33) and 0(0/33).The incidence of PONV was lower in the group S only in the T3 period after reversal than in the group N (χ2=4.227, P=0.040).However, there was no statistically significant difference in the incidence of PONV between the two groups of patients in other periods (all P>0.05). The recovery time for spontaneous breathing in patients in group S was (7.7±1.4) minutes, the extubation time was (12.4±5.3) minutes, and the safe exit time for anesthesia recovery was (12.3±3.4) minutes; the N groups were (13.9±2.0) minutes, (18.2±6.0) minutes, and (18.6±5.2) minutes, respectively; three time periods in group S were shorter than those in group N, and the differences were statistically significant (all P<0.05). The results regarding the occurrence of complications in patients with different levels of PONV at different time intervals after surgery in the two groups were as follows: in the T3 time period of group N, a significant difference was observed only in the occurrence of postoperative complications among patients with different levels of PONV (χ2=24.786, P<0.01). However, in the T4 time period, significant differences were found in the occurrence of postoperative complications among both the same level and different level PONV patients (χ2=15.435, 15.435, both P<0.01). Significant differences were also observed in the occurrence of postoperative complications among the same level and different level PONV patients in both the T3 and T4 time periods of group S (all P<0.01). Conclusion: Sugammadex can be used to reverse muscle relaxation in patients undergoing intracranial aneurysm intervention surgery,and it does not have a significant impact on the incidence of PONV, it can also optimize the quality of anesthesia recovery and reduce the incidence of complications after intracranial aneurysm embolization surgery.

Respiration-related variations in central venous pressure as predictors of fluid responsiveness in spontaneously breathing patients.

The hemodynamic parameters used to accurately predict fluid responsiveness (FR) in spontaneously breathing patients (SB) require specific material and expertise. Measurements of the central venous pressure (CVP) are relatively simple and, importantly, are feasible in many critically ill patients. We analyzed the accuracy of respiration-related variations in CVP (vCVP) to predict FR in SB patients, and examined the optimization of its measurement using a standardized, deep inspiratory maneuver. We performed a monocentric, prospective, diagnostic evaluation. Spontaneously breathing patients in intensive care units with a central venous catheter were prospectively included. vCVP was measured while the patient was spontaneously breathing, both with (vCVP-st) and without (vCVP-ns) a standardized inspiratory maneuver, and calculated as: Minimum inspiratory v-wave peak pressure - Maximum expiratory v-wave peak pressure. A passive leg raising-induced increase in the left ventricular outflow tract velocity-time integral ≥10% defined FR. Among 63 patients, 38 (60.3%) presented FR. vCVP-ns was not significantly different between responders and non-responders (-4.9 mmHg [-7.5; -3.1] vs. -4.1 mmHg [-5.4; -2.8], respectively; p = 0.15). vCVP-st was lower in responders than non-responders (-9.7 mmHg [-13.9; -6.2] vs. -3.6 mmHg [-10.6; -1.6], respectively; p = 0.004). A vCVP-st < -4.7 mmHg predicted FR with 89.5% sensitivity, a specificity of 56.0%, and an area under the ROC curve of 0.72 [95% CI: 0.58; 0.86] (p = 0.004). When a central venous catheter is present, elevated values for vCVP-st may be useful to identify spontaneously breathing patients unresponsive to volume expansion. Nevertheless, the necessity of performing a standardized, deep-inspiration maneuver may limit its clinical application.

Inferior vena cava ultrasound and other techniques for assessment of intravascular and extravascular volume: an update.

Goals of volume management are to accurately assess intravascular and extravascular volume and predict response to volume administration, vasopressor support or volume removal. Data are reviewed that support the following: (i)Dynamic parameters reliably guide volume administration and may improve clinical outcomes compared with static parameters, but some are invasive or only validated with mechanical ventilation without spontaneous breathing. (ii)Ultrasound visualization of inferior vena cava (IVC) diameter variations with respiration reliably assesses intravascular volume and predicts volume responsiveness. (iii)Although physiology of IVC respiratory variations differs with mechanical ventilation and spontaneous breathing, the IVC collapsibility index (CI) and distensibility index are interconvertible. (iv)Prediction of volume responsiveness by IVC CI is comparable for mechanical ventilation and spontaneous breathing patients. (v)Respiratory variations of subclavian/proximal axillary and internal jugular veins by ultrasound are alternative sites, with comparable reliability. (vi)Data support clinical applicability of IVC CI to predict hypotension with anesthesia, guide ultrafiltration goals, predict dry weight, predict intra-dialytic hypotension and assess acute decompensated heart failure. (vii)IVC ultrasound may complement ultrasound of heart and lungs, and abdominal organs for venous congestion, for assessing and managing volume overload and deresuscitation, renal failure and shock. (viii)IVC ultrasound has limitations including inadequate visualization. Ultrasound data should always be interpreted in clinical context. Additional studies are required to further assess and validate the role of bedside ultrasonography in clinical care.

In vitro evaluation of the potential use of snake-derived peptides in the treatment of respiratory infections using inhalation therapy: A proof of concept study

Inhalation therapy using nebulisers is an attractive non-invasive route for drug delivery, particularly for the treatment of lung infections with anti-inflammatory and anti-microbial compounds. This study evaluated the suitability of three snake-derived peptides (termed Sn1b, SnE1 and SnE1-F), which we have recently shown have potent anti-inflammatory and bacteriostatic activities, for nebulisation using a vibrating mesh nebuliser (VMN). The effect of nebulisation on peptide concentration, stability and function were assessed, prior to progression to aerodynamic particle size distribution, and in vitro drug delivery in simulated adult spontaneous breathing and mechanical ventilated patient models. When nebulised, all three peptides exhibited similar functions to their non-nebulised counterparts and were found to be respirable during simulated mechanical ventilation. Based on the assessment of the droplet distributions of nebulised peptides using a Next Generation Impactor (NGI) demonstrated that if administered in vivo each peptide would likely be delivered to the lower airways. These data suggest that nebulisation using a VMN is a viable means of anti-microbial / anti-inflammatory peptide delivery targeting microbial respiratory infections, and possibly even systemic infections.

Monitoring haemodynamic changes during transjugular portosystemic shunt insertion with electric cardiometry in sedated and spontaneous breathing patients. A diagnostic test accuracy study.

Transjugular intrahepatic portosystemic shunt (TIPS) allows a high blood volume into systemic circulation abruptly. The primary aim of the study was to investigate the effect of TIPS on systemic, portal hemodynamics, and electric cardiometry (EC) parameters in sedated and spontaneous breathing patients. Secondary aims?? Adult consecutive hepatic patients scheduled for elective TIPS were included. Patients were sedated with bispectral index-guided propofol infusion + fentanyl boluses. EC parameters, i.e., cardiac output (CO) and systemic vascular resistance (SVR) were noted. Noninvasive blood pressure, heart rate, central venous pressure (CVP, cmH2O), and portal venous pressure (PVP, cmH2O) were measured pre- and post-TIPS. Thirty-six people were enrolled (n = 25 included) from Aug 2018 to Dec 2019. Data (expressed in median (IQ)) were: age 33 (27-40) years, body mass index 24 (22.0-27) kg/m2, child A 60%, B 36%, and C 4%. Post-TIPS, PVP decreased (from 40 [37-45] to 34 [27-37] mmHg, P < 0.001), whereas CVP increased (from 7 [4-10] to 16 [10.0-19.0] mmHg, P < 0.001). The CO increased (P = 0.03) and SVR reduced (P = 0.012). The reduction in PVP following successful TIPS insertion elevated the CVP abruptly. EC was able to monitor an immediate increase in the CO and a reduction in SVR in association with the above PVP and CVP changes. The results of this unique study indicate that EC monitoring is promising; however, further evaluation in a larger population and in correlation with other gold-standard CO monitors is still indicated.

Homogenizing effect of PEEP on tidal volume distribution during neurally adjusted ventilatory assist: study of an animal model of acute respiratory distress syndrome

BackgroundThe physiological response and the potentially beneficial effects of positive end-expiratory pressure (PEEP) for lung protection and optimization of ventilation during spontaneous breathing in patients with acute respiratory distress syndrome (ARDS) are not fully understood. The aim of the study was to compare the effect of different PEEP levels on tidal volume distribution and on the ventilation of dependent lung region during neurally adjusted ventilatory assist (NAVA).MethodsARDS-like lung injury was induced by using saline lavage in 10 anesthetized and spontaneously breathing farm-bred pigs. The animals were ventilated in NAVA modality and tidal volume distribution as well as dependent lung ventilation were assessed using electric impedance tomography during the application of PEEP levels from 0 to 15 cmH20, in steps of 3 cmH20. Tidal volume distribution and dependent fraction of ventilation were analysed using Wilcoxon signed rank test. Furthermore, airway, esophageal and transpulmonary pressure, as well as airway flow and delivered volume, were continuously measured during the assisted spontaneous breathing.ResultsIncreasing PEEP improved oxygenation and re-distributed tidal volume. Specifically, ventilation distribution changed from a predominant non-dependent to a more even distribution between non-dependent and dependent areas of the lung. Dependent fraction of ventilation reached 47 ± 9% at PEEP 9 cmH20. Further increasing PEEP led to a predominant dependent ventilation.ConclusionDuring assisted spontaneous breathing in this model of induced ARDS, PEEP modifies the distribution of ventilation and can achieve a homogenizing effect on its spatial arrangement. The study indicates that PEEP is an important factor during assisted spontaneous breathing and that EIT can be of valuable interest when titrating PEEP level during spontaneous breathing, by indicating the most homogeneous distribution of gas volumes throughout the PEEP spectrum.

Estimating the incidence of spontaneous breathing effort of mechanically ventilated patients using a non-linear auto regressive (NARX) model

Background and objectiveMechanical ventilation (MV) provides breathing support for acute respiratory distress syndrome (ARDS) patients in the intensive care unit, but is difficult to optimize. Too much, or too little of pressure or volume support can cause further ventilator-induced lung injury, increasing length of MV, cost and mortality. Patient-specific respiratory mechanics can help optimize MV settings. However, model-based estimation of respiratory mechanics is less accurate when patient exhibit un-modeled spontaneous breathing (SB) efforts on top of ventilator support. This study aims to estimate and quantify SB efforts by reconstructing the unaltered passive mechanics airway pressure using NARX model. MethodsNon-linear autoregressive (NARX) model is used to reconstruct missing airway pressure due to the presence of spontaneous breathing effort in mv patients. Then, the incidence of SB patients is estimated. The study uses a total of 10,000 breathing cycles collected from 10 ARDS patients from IIUM Hospital in Kuantan, Malaysia. In this study, there are 2 different ratios of training and validating methods. Firstly, the initial ratio used is 60:40 which indicates 600 breath cycles for training and remaining 400 breath cycles used for testing. Then, the ratio is varied using 70:30 ratio for training and testing data. Results and discussionThe mean residual error between original airway pressure and reconstructed airway pressure is denoted as the magnitude of effort. The median and interquartile range of mean residual error for both ratio are 0.0557 [0.0230 - 0.0874] and 0.0534 [0.0219 - 0.0870] respectively for all patients. The results also show that Patient 2 has the highest percentage of SB incidence and Patient 10 with the lowest percentage of SB incidence which proved that NARX model is able to perform for both higher incidence of SB effort or when there is a lack of SB effort. ConclusionThis model is able to produce the SB incidence rate based on 10% threshold. Hence, the proposed NARX model is potentially useful to estimate and identify patient-specific SB effort, which has the potential to further assist clinical decisions and optimize MV settings.

Prone position in COVID 19-associated acute respiratory failure.

Purpose of reviewProne position has been widely used in the COVID-19 pandemic, with an extension of its use in patients with spontaneous breathing (’awake prone’). We herein propose a review of the current literature on prone position in mechanical ventilation and while spontaneous breathing in patients with COVID-19 pneumonia or COVID-19 ARDS.Recent findingsA literature search retrieved 70 studies separating whether patient was intubated (24 studies) or nonintubated (46 studies). The outcomes analyzed were intubation rate, mortality and respiratory response to prone. In nonintubated patient receiving prone position, the main finding was mortality reduction in ICU and outside ICU setting.SummaryThe final results of the several randomized control trials completed or ongoing are needed to confirm the trend of these results. In intubated patients, observational studies showed that responders to prone in terms of oxygenation had a better survival than nonresponders.

Aerosol particle concentrations with different oxygen devices and interfaces for spontaneous breathing patients with tracheostomy: a randomised crossover trial.

For stable spontaneously breathing tracheostomy patients with uncuffed airways, different humidification devices and interfaces did not generate clinically significant differences of aerosol particle concentrations https://bit.ly/2Y1HSO2

Inhaled high dose nitric oxide is a safe and effective respiratory treatment in spontaneous breathing hospitalized patients with COVID-19 pneumonia

BackgroundInhaled nitric oxide (NO) is a selective pulmonary vasodilator. In-vitro studies report that NO donors can inhibit replication of SARS-CoV-2. This multicenter study evaluated the feasibility and effects of high-dose inhaled NO in non-intubated spontaneously breathing patients with Coronavirus disease-2019 (COVID-19). MethodsThis is an interventional study to determine whether NO at 160 parts-per-million (ppm) inhaled for 30 min twice daily might be beneficial and safe in non-intubated COVID-19 patients. ResultsTwenty-nine COVID-19 patients received a total of 217 intermittent inhaled NO treatments for 30 min at 160 ppm between March and June 2020. Breathing NO acutely decreased the respiratory rate of tachypneic patients and improved oxygenation in hypoxemic patients. The maximum level of nitrogen dioxide delivered was 1.5 ppm. The maximum level of methemoglobin (MetHb) during the treatments was 4.7%. MetHb decreased in all patients 5 min after discontinuing NO administration. No adverse events during treatment, such as hypoxemia, hypotension, or acute kidney injury during hospitalization occurred.In our NO treated patients, one patient of 29 underwent intubation and mechanical ventilation, and none died. The median hospital length of stay was 6 days [interquartile range 4–8]. No discharged patients required hospital readmission nor developed COVID-19 related long-term sequelae within 28 days of follow-up. ConclusionsIn spontaneous breathing patients with COVID-19, the administration of inhaled NO at 160 ppm for 30 min twice daily promptly improved the respiratory rate of tachypneic patients and systemic oxygenation of hypoxemic patients. No adverse events were observed. None of the subjects was readmitted or had long-term COVID-19 sequelae.

Rationale and design of the Prone Position and Respiratory Outcomes in Non-intubated COVID-19 PatiEnts: The “PRONE” Study

While benefits of prone position in mechanically-ventilated patients have been well-described, a randomized-control trial to determine the effects of prone positioning in awake, spontaneously-breathing patients with an acute pneumonia has not been previously conducted. Prone Position and Respiratory Outcomes in Non-Intubated COVID-19 PatiEnts: the “PRONE” Study (PRONE) was conducted in non-intubated hospitalized patients with coronavirus disease 2019 (COVID-19) pneumonia as defined by respiratory rate ≥ 20/min or an oxyhemoglobin saturation (SpO2) ≤ 93% without supplemental oxygen [1]. The PRONE trial was designed to investigate the effects of prone positioning on need for escalation in respiratory support, as defined by need for transition to a higher acuity level of care, increased fraction of inspired oxygen (FiO2), or the initiation of invasive mechanical ventilation. Secondary objectives were to assess the duration of effect of prone positioning on respiratory parameters such as respiratory rate and SpO2, as well as other outcomes such as time to discharge or transition in level of care.

Real-Time Evaluation of Optic Nerve Sheath Diameter (ONSD) in Awake, Spontaneously Breathing Patients.

(1) Background: Reliable ultrasonographic measurements of optic nerve sheath diameter (ONSD) to detect increased intracerebral pressure (ICP) has not been established in awake patients with continuous invasive ICP monitoring. Therefore, in this study, we included fully awake patients with and without raised ICP and correlated ONSD with continuously measured ICP values. (2) Methods: In a prospective study, intracranial pressure (ICP) was continuously measured in 25 patients with an intraparenchymatic P-tel probe. Ultrasonic measurements were carried out three times for each optic nerve in vertical and horizontal directions. ONSD measurements and ICP were correlated. Patients with ICP of 2.0–10.0 mmHg were compared with patients suffering from an ICP of 10.1–24.2 mmHg. (3) Results: In all patients, the ONSD vertical and horizontal measurement for both eyes correlated well with the ICP (Pearson R = 0.68–0.80). Both measurements yielded similar results (Bland-Altman: vertical bias: −0.09 mm, accuracy: ±0.66 mm; horizontal bias: −0.06 mm, accuracy: ±0.48 mm). For patients with an ICP of 2.0–10.0 mmHg compared to an ICP of 10.1–24.2, ROC (receiver operating characteristic) analyses showed that ONSD measurement accurately predicts elevated ICP (optimal cut-off value 5.05 mm, AUC of 0.91, sensitivity 92% and specificity 90%, p < 0.001). (4) Conclusions: Ultrasonographic measurement of ONSD in awake, spontaneously breathing patients provides a valuable method to evaluate patients with suspected increased ICP. Additionally, it provides a potential tool for rapid assessment of ICP at the bedside and to identify patients at risk for a poor neurological outcome.

Non-invasive ventilatory support and high-flow nasal oxygen as first-line treatment of acute hypoxemic respiratory failure and ARDS.

The role of non-invasive respiratory support (high-flow nasal oxygen and noninvasive ventilation) in the management of acute hypoxemic respiratory failure and acute respiratory distress syndrome is debated. The oxygenation improvement coupled with lung and diaphragm protection produced by non-invasive support may help to avoid endotracheal intubation, which prevents the complications of sedation and invasive mechanical ventilation. However, spontaneous breathing in patients with lung injury carries the risk that vigorous inspiratory effort, combined or not with mechanical increases in inspiratory airway pressure, produces high transpulmonary pressure swings and local lung overstretch. This ultimately results in additional lung damage (patient self-inflicted lung injury), so that patients intubated after a trial of noninvasive support are burdened by increased mortality. Reducing inspiratory effort by high-flow nasal oxygen or delivery of sustained positive end-expiratory pressure through the helmet interface may reduce these risks. In this physiology-to-bedside review, we provide an updated overview about the role of noninvasive respiratory support strategies as early treatment of hypoxemic respiratory failure in the intensive care unit. Noninvasive strategies appear safe and effective in mild-to-moderate hypoxemia (PaO2/FiO2 > 150 mmHg), while they can yield delayed intubation with increased mortality in a significant proportion of moderate-to-severe (PaO2/FiO2 ≤ 150 mmHg) cases. High-flow nasal oxygen and helmet noninvasive ventilation represent the most promising techniques for first-line treatment of severe patients. However, no conclusive evidence allows to recommend a single approach over the others in case of moderate-to-severe hypoxemia. During any treatment, strict physiological monitoring remains of paramount importance to promptly detect the need for endotracheal intubation and not delay protective ventilation.

The Use of Aerosolized Medications in Adult Intensive Care Unit Patients: A Prospective, Multicenter, Observational, Cohort Study.

Background: Only limited data are available on the real-life clinical utilization of aerosolized medications in intensive care unit (ICU) patients. Exploring the utilization of aerosolized medications in the ICU may contribute to develop appropriate education and improve the quality of aerosol therapy. Methods: A 2-week, prospective, multicenter, observational, cohort study was conducted to record how the aerosolized medications were utilized in the Chinese ICUs, including indications, medications used in solo or combination, dosage, and side-effects in adult patients. Results: A total of 1006 patients from 28 ICUs were enrolled, of which 389 (38.7%) received aerosol therapy. The most common indications for aerosol therapy were difficulty in secretion management (23.1%) and chronic obstructive pulmonary disease exacerbation (18.5%). The combination of inhaled corticosteroids and short-acting muscarinic antagonist was the most commonly used medication (19.5%, 76/389). Ninety-two percent (358/389) of the patients did not have any side effects during aerosol therapy. More patients in the group with mechanical ventilation received bronchodilators than spontaneous breathing patients (81.3% vs. 55.5%, p < 0.001), and more patients who breathed spontaneously through a tracheostomy received mucus-regulating agents than other patients (70% vs. 37.9%, p = 0.004). Conclusion: In mainland China, more than one-third of adult ICU patients received aerosol therapy. Medications utilized during aerosol therapy were variable in patients with different respiratory support. To promote appropriate use of aerosolized medications, high-quality randomized, controlled trials and clinical guidance on aerosolized medication indications and dosing are needed to improve clinical outcomes.

Estimation of change in pleural pressure in assisted and unassisted spontaneous breathing pediatric patients using fluctuation of central venous pressure: A preliminary study.

It is important to evaluate the size of respiratory effort to prevent patient self-inflicted lung injury and ventilator-induced diaphragmatic dysfunction. Esophageal pressure (Pes) measurement is the gold standard for estimating respiratory effort, but it is complicated by technical issues. We previously reported that a change in pleural pressure (ΔPpl) could be estimated without measuring Pes using change in CVP (ΔCVP) that has been adjusted with a simple correction among mechanically ventilated, paralyzed pediatric patients. This study aimed to determine whether our method can be used to estimate ΔPpl in assisted and unassisted spontaneous breathing patients during mechanical ventilation. The study included hemodynamically stable children (aged <18 years) who were mechanically ventilated, had spontaneous breathing, and had a central venous catheter and esophageal balloon catheter in place. We measured the change in Pes (ΔPes), ΔCVP, and ΔPpl that was calculated using a corrected ΔCVP (cΔCVP-derived ΔPpl) under three pressure support levels (10, 5, and 0 cmH2O). The cΔCVP-derived ΔPpl value was calculated as follows: cΔCVP-derived ΔPpl = k × ΔCVP, where k was the ratio of the change in airway pressure (ΔPaw) to the ΔCVP during airway occlusion test. Of the 14 patients enrolled in the study, 6 were excluded because correct positioning of the esophageal balloon could not be confirmed, leaving eight patients for analysis (mean age, 4.8 months). Three variables that reflected ΔPpl (ΔPes, ΔCVP, and cΔCVP-derived ΔPpl) were measured and yielded the following results: -6.7 ± 4.8, - -2.6 ± 1.4, and - -7.3 ± 4.5 cmH2O, respectively. The repeated measures correlation between cΔCVP-derived ΔPpl and ΔPes showed that cΔCVP-derived ΔPpl had good correlation with ΔPes (r = 0.84, p< 0.0001). ΔPpl can be estimated reasonably accurately by ΔCVP using our method in assisted and unassisted spontaneous breathing children during mechanical ventilation.

Mechanical ventilation in septic shock

The aim of this study was to review the most recent literature on mechanical ventilation strategies in patients with septic shock. Indirect clinical trial evidence has refined the use of neuromuscular blocking agents, positive end-expiratory pressure (PEEP) and recruitment manoeuvres in septic shock patients with acute respiratory distress syndrome. Weaning strategies and devices have also been recently evaluated. The role of lung protective ventilation in patients with healthy lungs, while recognized, still needs to be further refined. The possible detrimental effects of spontaneous breathing in patients who develop acute respiratory distress syndrome is increasingly recognized, but clinical trial evidence is still lacking to confirm this hypothesis. A new concept of lung and diaphragm protective is emerging in the critical care literature, but its application will need a complex intervention implementation approach to allow adequate scrutiny of this concept and uptake by clinicians. Many advances in the management of the mechanically ventilated patient with sepsis and septic shock have occurred in recent years, but clinical trial evidence is still necessary to translate new hypotheses to the bedside and find the right balance between benefits and risks of these new strategies.

Spontaneous breathing for managing analgesia during balanced anesthesia with remifentanil and desflurane: a prospective, single center randomized controlled trial.

The main goal of anesthesiology is to achieve the best level of analgesia and a fast recovery of consciousness following anesthesia. The preservation of spontaneous breathing during general anesthesia with anesthetic gases is practiced by many anesthetists. However, very few studies have dealt with these positive properties of volatile anesthetics such as sevoflurane or desflurane. Remifentanil is a very short half-life opiate that combines sufficient intra-operative analgesia with a fast post-operative recovery time. We tested the hypothesis that spontaneous breathing can reduce overdosing with remifentanil during desflurane anesthesia. In this prospective, single center, multiple anesthetist study, 30 patients were randomized into two groups (volume-controlled ventilation mode and spontaneous breathing). The spontaneous breathing group showed a significantly lower post-operative pain level than the volume-controlled ventilation mode group. Furthermore, less remifentanil as well as less piritramide was needed in the spontaneous breathing group compared with volume-controlled ventilation mode. It was possible to achieve spontaneous breathing in all patients with 0.6 minimum alveolar concentration desflurane, in order to control the remifentanil rate and prevent an overdose. All spontaneous breathing patients had low intra- and post-operative pain levels and the need for analgesics was equal to or lower than that in the volume-controlled ventilation mode group. By reducing the intra-operative amount of opiates, both the post-operative pain and the amount of post-operative analgesia required can be reduced. A balanced anesthesia with spontaneous intra-operative breathing is needed to determine the required amount of opiates. This study was approved by the Ethic Committee of the Ruhr-University of Bochum (approval No. 2435) in September, 2004.

Indirect calorimetry: best results with close monitoring of the carbon dioxide fraction in exhaled air

This study describes methods to improve resting energy expenditure (REE) estimated by the indirect calorimetry by evaluating predictors for the achievement of steady-state conditions (SSC). Cross-sectional study carried out with 20 women (30.2 ± 4.1 years; 27.8 ± 6.7 kg/m2). Indirect calorimetry was performed with the Quark RMR® calorimeter, during a 15-min period. VO2 consumption and VCO2 production were measured and data was collected every 5 s. Specific spreadsheet was used to compute the values of Steady REE and Software REE (deltaREE). Bias and concordance between values were assessed by the Bland-Altman plot and Lin’s correlation coefficient. There is an almost perfect concordance between Software REE and Steady REE (p = 0.001). Steady% was important for predicting deltaREE while variation of carbon dioxide exhaled (CVFECO2) was significant to predict Steady%. Also, CVFECO2 was strongly and significantly correlated with the CV of VO2 (r = 0.83, p = 0001) and with the CV of VCO2 (r = 0.9, p = 0001). FECO2 should be sustained without huge variations to ensure SSC when using a calorimeter based on the canopy dilution technique with spontaneous breathing patients of similar characteristics. Also, these results suggest that since SSC occurs at least one time in the test, the Software REE may be considered reliable.