Mechanical ventilation: past lessons and the near future

Safety and Effectiveness of Carbon Dioxide Removal CO2RESET Device in Critically Ill Patients

BACKGROUND

In this retrospective study, we report the effectiveness and safety of a dedicated extracorporeal carbon dioxide removal (ECCO₂R) device in critically ill patients.

METHODS

Adult patients on mechanical ventilation due to acute respiratory distress syndrome (ARDS) or decompensated chronic obstructive pulmonary disease (dCOPD), who were treated with a dedicated ECCO₂R device (CO2RESET, Eurosets, Medolla, Italy) in case of hypercapnic acidemia, were included. Repeated measurements of CO₂ removal (VCO₂) at baseline and 1, 12, and 24 h after the initiation of therapy were recorded.

RESULTS

Over a three-year period, 11 patients received ECCO₂R (median age 60 [43-72] years) 3 (2-39) days after ICU admission; nine patients had ARDS and two had dCOPD. Median baseline pH and PaCO₂ levels were 7.27 (7.12-7.33) and 65 (50-84) mmHg, respectively. With a median ECCO₂R blood flow of 800 (500-800) mL/min and maximum gas flow of 6 (2-14) L/min, the VCO₂ at 12 h after ECCO₂R initiation was 157 (58-183) mL/min. Tidal volume, respiratory rate, and driving pressure were significantly reduced over time. Few side effects were reported.

CONCLUSIONS

In this study, a dedicated ECCO₂R device provided a high VCO₂ with a favorable risk profile.

A Pilot Standardized Simulation-Based Mechanical Ventilation Curriculum Targeting Pulmonary and Critical Care Medicine and Critical Care Medicine Fellows

Introduction  The mastery of mechanical ventilation (MV) management is challenging, as it requires the integration of physiological and technological knowledge with critical thinking. Our aim was to create a standardized curriculum with assessment tools based on evidence-based practices to identify the skill deficit and improve knowledge in MV management. Methods  For 3 years, 3 hours of standardized curriculum for each first-year pulmonary critical care medicine (PCCM) and critical care medicine (CCM) fellows was integrated into the orientation (chronologically): (1) a baseline knowledge pretest; (2) a 1-hour one-on-one case-based simulation session with debriefing. A 34-item competency checklist was used to assess critically thinking and skills and guide the debriefing; (3) a 1-hour group didactic on respiratory mechanics and physiology; (4) a 45-minute hands-on session in small groups of one to three fellows for basic knobology, waveforms, and various modes of mechanical ventilators; (5) a 15-minute group bedside teaching of vented patients covering topics such as techniques to alleviate dyssynchrony and advanced ventilator modes; (6) a one-on-one simulation reassessment session; (7) a knowledge posttest. Fellows' performances at baseline, 1-month posttest, and end-of-first year post-test were compared. Results  Fellows ( n  = 24) demonstrated significant improvement at 1-month posttest in knowledge (54.2% ± 11.0 vs. 76.6 ± 11.7%, p  < 0.001) and MV competency (40.7 ± 11.0% vs. 69.7 ± 9.3%, p  < 0.001), compared with pretest. These improvements were retained at the end-of-year reassessments (knowledge 75.1 ± 14.5% and MV competency 85.5 ± 8.7%; p  < 0.001). Conclusion  Standardized simulation-based MV curriculum may improve the medical knowledge competency, and confidence of first-year PCCM and CCM fellows toward MV management before encountering actual ventilated patients.

Effect of high-frequency oscillatory ventilation combined with prone positioning in infants with acute respiratory distress syndrome after congenital heart surgery: A prospective randomized controlled trial

Objectives

This study aimed to evaluate the effect of high-frequency oscillatory ventilation, (HFOV) combined with prone positioning, on oxygenation and pulmonary ventilation in infants with acute respiratory distress syndrome (ARDS) after congenital heart surgery.

Design

A randomized controlled trial.

Setting

A single-center study at a tertiary teaching hospital.

Participants

Patients with postoperative ARDS after congenital heart disease were divided randomly into the following 2 groups: HFOV combined with prone position (HFOV-PP), and HFOV combined with supine position (HFOV-SP).

Interventions

The primary outcomes were the PaO₂/F_IO₂ ratio and the oxygenation index after the intervention, and the secondary outcomes were respiratory variables, hemodynamics, complications, and other short-term outcomes.

Results

Sixty-five eligible infants with ARDS were randomized to either the HFOV-PP (n = 32) or HFOV-SP (n = 33) group. No significant difference in baseline data was found between the 2 groups (p > 0.05). Oxygenation was improved in both groups after HFOV intervention. Compared with the HFOV-SP group, the HFOV-PP group had significantly increased PaO₂/F_IO₂ and oxygenation index and a shorter duration of invasive ventilation and length of cardiac intensive care unit stay. No serious complications occurred in the 2 groups.

Conclusion

HFOV-PP significantly improved oxygenation in infants with ARDS after cardiac surgery and had no serious complications.

A low-cost field ventilator: An urgent global need

Modern ventilators are increasingly compact and able to deliver a wide range of ventilator modes and sophisticated monitoring capabilities. However, the global availability of ventilators is woefully short of demand. Data on intensive care units (ICUs), a proxy measure for hospital ventilator capacity in low and middle-income countries (LMIC's), suggest that capacity is extremely limited where it exists at all. In LMIC's, the four most common indications for mechanical ventilation (MV) in ICUs are post-surgical care, sepsis, trauma, and maternal peripartum or neonatal complications. A significant majority of these cases can be managed with intervention involving a short course of MV. Widespread and timely access to MV can thus effectively be used to help patients in these settings and improve outcomes. This paper implores this need and highlights the requirements for a low-cost ventilator or a respiratory support device.

Effect of High-Frequency Oscillatory Ventilation Combined With Pulmonary Surfactant in the Treatment of Acute Respiratory Distress Syndrome After Cardiac Surgery: A Prospective Randomised Controlled Trial

Background: This study aimed to evaluate the effects of pulmonary surfactant (PS) combined with high-frequency oscillatory ventilation (HFOV) or conventional mechanical ventilation (CMV) in infants with acute respiratory distress syndrome (ARDS) after congenital cardiac surgery.

Methods: A total of 61 infants with ARDS were eligible and were randomised to the CMV + PS group (n = 30) or the HFOV + PS group (n = 31) between January 2020 and December 2020. The primary outcomes were the changes in arterial blood gas parameters. The duration of mechanical ventilation, length of hospitalisation and the incidence of complications were considered secondary outcomes.

Results: A total of 61 infants completed the study. In the HFOV + PS group, the blood gas analysis results were significantly improved (P < 0.05), while the duration of mechanical ventilation and length of hospitalisation were shorter than the CMV + PS group (P < 0.05). However, the incidence of complications was not different between the two groups (P > 0.05).

Conclusions: Compared with the CMV + PS group, the HFOV + PS group showed significantly improved ABG variables and had a shortened length of hospitalisation and mechanical ventilation in infants with ARDS after cardiac surgery.

Clinical Trial Registration: Chinese Clinical Trial Registry; Number: ChiCTR2000039457.

Mechanical Ventilator Parameter Estimation for Lung Health through Machine Learning

Patients whose lungs are compromised due to various respiratory health concerns require mechanical ventilation for support in breathing. Different mechanical ventilation settings are selected depending on the patient’s lung condition, and the selection of these parameters depends on the observed patient response and experience of the clinicians involved. To support this decision-making process for clinicians, good prediction models are always beneficial in improving the setting accuracy, reducing treatment error, and quickly weaning patients off the ventilation support. In this study, we developed a machine learning model for estimation of the mechanical ventilation parameters for lung health. The model is based on inverse mapping of artificial neural networks with the Graded Particle Swarm Optimizer. In this new variant, we introduced grouping and hierarchy in the swarm in addition to the general rules of particle swarm optimization to further improve its prediction performance of the mechanical ventilation parameters. The machine learning model was trained and tested using clinical data from canine and feline patients at the University of Georgia College of Veterinary Medicine. Our model successfully generated a range of parameter values for the mechanical ventilation applied on test data, with the average prediction values over multiple trials close to the target values. Overall, the developed machine learning model should be able to predict the mechanical ventilation settings for various respiratory conditions for patient’s survival once the relevant data are available.

Patient–Ventilator Interaction Testing Using the Electromechanical Lung Simulator xPULM™ during V/A-C and PSV Ventilation Mode

During mechanical ventilation, a disparity between flow, pressure and volume demands of the patient and the assistance delivered by the mechanical ventilator often occurs. This paper introduces an alternative approach of simulating and evaluating patient–ventilator interactions with high fidelity using the electromechanical lung simulator xPULM™. The xPULM™ approximates respiratory activities of a patient during alternating phases of spontaneous breathing and apnea intervals while connected to a mechanical ventilator. Focusing on different triggering events, volume assist-control (V/A-C) and pressure support ventilation (PSV) modes were chosen to test patient–ventilator interactions. In V/A-C mode, a double-triggering was detected every third breathing cycle, leading to an asynchrony index of 16.67%, which is classified as severe. This asynchrony causes a significant increase of peak inspiratory pressure (7.96 ± 6.38 vs. 11.09 ± 0.49 cmH2O, p < 0.01)) and peak expiratory flow (−25.57 ± 8.93 vs. 32.90 ± 0.54 L/min, p < 0.01) when compared to synchronous phases of the breathing simulation. Additionally, events of premature cycling were observed during PSV mode. In this mode, the peak delivered volume during simulated spontaneous breathing phases increased significantly (917.09 ± 45.74 vs. 468.40 ± 31.79 mL, p < 0.01) compared to apnea phases. Various dynamic clinical situations can be approximated using this approach and thereby could help to identify undesired patient–ventilation interactions in the future. Rapidly manufactured ventilator systems could also be tested using this approach.

The application of non-invasive and invasive mechanical ventilation in the first episode of acute respiratory failure

Acute respiratory failure (RF) is a life-threatening syndrome. This study investigated the application of two major clinical strategies, non-invasive mechanical ventilation (NIV) and invasive mechanical ventilation (IMV), in the first episode of acute RF. Data from the longitudinal health insurance database, which included 1,000,000 insured citizens, were used. The NIV group consisted of 1201 patients and the IMV group consisted of 16,072 patients. Chi-square test and t test were applied to determine the differences in categorical and continuous variables. Further analysis was performed by using univariate and multivariable logistic regression and Poisson regression. There was a significant increase of 733% in the number of NIV users from 2000 to 2012. NIV use was frequently observed in old-age persons (aOR 3.99, 95% CI 3.06-5.21 for those aged ≥ 80 years), women (aOR 1.33, 95% CI 1.18-1.50), patients admitted to a high-level hospital (aOR 1.95, 95% CI 1.63-2.34 for those admitted to a medical center), and patients with a higher Charlson comorbidity index (CCI, aOR 1.38-1.66 for those CCI ≥ 2). In addition, patients with chronic pulmonary disease, cancer, and congestive heart failure were predominant in NIV users and were significantly associated with NIV use. Overall, the use of NIV has markedly increased over the past few years. Persons of advanced age, women, patients admitted to a high-level hospital, and patients with multiple comorbidities were associated with more frequent NIV use. Chronic pulmonary disease, cancer, and congestive heart failure were most important comorbidities for NIV use.

Implementing the ABCDE Bundle, Critical-Care Pain Observation Tool, and Richmond Agitation-Sedation Scale to Reduce Ventilation Time

Prolonged mechanical ventilation of patients in intensive care units across the United States consumes billions of health care dollars every year. Using the awakening and breathing coordination, delirium monitoring/management, and early mobility (ABCDE) bundle along with the Critical-Care Pain Observation Tool and the Richmond Agitation-Sedation Scale combines the best available evidence to optimize outcomes for critically ill patients. This study is the first to examine the effects of implementing the ABCDE bundle, the Critical-Care Pain Observation Tool, and the Richmond Agitation-Sedation Scale together in a coordinated effort across multiple disciplines. The aim of using this combination of evidence-based tools is to reduce ventilation time by reducing oversedation, decreasing the incidence of delirium, and improving pain management.

A physiology-based mathematical model for the selection of appropriate ventilator controls for lung and diaphragm protection

Mechanical ventilation is used to sustain respiratory function in patients with acute respiratory failure. To aid clinicians in consistently selecting lung- and diaphragm-protective ventilation settings, a physiology-based decision support system is needed. To form the foundation of such a system, a comprehensive physiological model which captures the dynamics of ventilation has been developed. The Lung and Diaphragm Protective Ventilation (LDPV) model centers around respiratory drive and incorporates respiratory system mechanics, ventilator mechanics, and blood acid–base balance. The model uses patient-specific parameters as inputs and outputs predictions of a patient’s transpulmonary and esophageal driving pressures (outputs most clinically relevant to lung and diaphragm safety), as well as their blood pH, under various ventilator and sedation conditions. Model simulations and global optimization techniques were used to evaluate and characterize the model. The LDPV model is demonstrated to describe a CO₂ respiratory response that is comparable to what is found in literature. Sensitivity analysis of the model indicate that the ventilator and sedation settings incorporated in the model have a significant impact on the target output parameters. Finally, the model is seen to be able to provide robust predictions of esophageal pressure, transpulmonary pressure and blood pH for patient parameters with realistic variability. The LDPV model is a robust physiological model which produces outputs which directly target and reflect the risk of ventilator-induced lung and diaphragm injury. Ventilation and sedation parameters are seen to modulate the model outputs in accordance with what is currently known in literature.

Monitoring Lung Mechanics during Mechanical Ventilation using Machine Learning Algorithms

Evaluation of lung mechanics is the primary component for designing lung protective optimal ventilation strategies. This paper presents a machine learning approach for bedside assessment of respiratory resistance (R) and compliance (C). We develop machine learning algorithms to track flow rate and airway pressure and estimate R and C continuously and in real-time. An experimental study is conducted, by connecting a pressure control ventilator to a test lung that simulates various R and C values, to gather sensor data for validation of the devised algorithms. We develop supervised learning algorithms based on decision tree, decision table, and Support Vector Machine (SVM) techniques to predict R and C values. Our experimental results demonstrate that the proposed algorithms achieve 90.3%, 93.1%, and 63.9% accuracy in assessing respiratory R and C using decision table, decision tree, and SVM, respectively. These results along with our ability to estimate R and C with 99.4% accuracy using a linear regression model demonstrate the potential of the proposed approach for constructing a new generation of ventilation technologies that leverage novel computational models to control their underlying parameters for personalized healthcare and context-aware interventions.

Evaluation of white sweet potato tube-feeding formula in elderly diabetic patients: a randomized controlled trial

BACKGROUND

Elderly people with type 2 diabetes mellitus (T2DM) have an increased risk of diabetes-related microvascular and macrovascular complications, thus diabetic patients with a functioning gastrointestinal tract but without sufficient oral intake require enteral nutrition (EN) formulas to control blood glucose. White sweet potato (WSP) was a kind of sweet potato could provide a healthy carbohydrate source to EN formula. The aim of this study was to examine at risk of malnutrition T2DM patients whether a WSP-EN would attenuate glucose response and elevate nutritional index compared to a standard polymeric formulas.

METHODS

In this randomized, parallel, placebo-controlled, pilot clinical trial to investigate the effects of EN with WSP on aged residents with T2DM in long-term care institutions. In total, 54 eligible participants were randomly assigned to either the non-WSP-EN or WSP-EN group. For 60 days, the WSP-EN group received a WSP formula through nasogastric tube via a stoma with a large-bore syringe. The participants received EN of standard polymeric formulas without WSP in the non-WSP-EN group.

RESULTS

The body weight, body mass index, Mini Nutritional Assessment score, and Geriatric Nutritional Risk Index were significantly higher in the WSP-EN group (p < 0.05). Moreover, the WSP-EN intervention reduced glycated hemoglobin levels (6.73% ± 1.47% vs. 6.40% ± 1.16%), but increased transferrin (223.06 ± 38.85 vs. 245.85 ± 46.08 mg/dL), high-density lipoprotein cholesterol (42.13 ± 10.56 vs. 44.25 ± 8.43 mg/dL), and vitamin A (2.45 ± 0.77 vs 2.74 ± 0.93 μM) levels (p < 0.05). In addition, there was no important side effects including gastrointestinal intolerance with prescribed doses in our WSP-EN treated patients when compared with control ones.

CONCLUSIONS

The results suggest WSP incorporated into enteral formulas can improve nutrition status and glycemic control in elderly diabetic patients.

TRIAL REGISTRATION

NCT02711839, registered 27 May 2015.

Part II: The Effects of Aromatherapy and Guided Imagery for the Symptom Management of Anxiety, Pain, and Insomnia in Critically Ill Patients: An Integrative Review of Current Literature

This review is part II of a 2-part series that presents evidence on the effectiveness of aromatherapy and guided imagery for the symptom management of anxiety, pain, and insomnia in adult critically ill patients. Evidence from this review supports the use of aromatherapy for management of pain, insomnia, and anxiety in critically ill patients. Evidence also supports the use of guided imagery for managing these symptoms in critical care; however, the evidence is sparse, mixed, and weak. More studies with larger samples and stronger designs are needed to further establish efficacy of guided imagery for the management of anxiety, pain, and insomnia of critically ill patients; to accomplish this, standardized evidence-based intervention protocols to ensure comparability and to establish optimal effectiveness are needed. Discussion and recommendations related to the use of these therapies in practice and needs for future research in these areas were generated.

Part I: The Effects of Music for the Symptom Management of Anxiety, Pain, and Insomnia in Critically Ill Patients: An Integrative Review of Current Literature

Critical care environments are known for provoking anxiety, pain, and sleeplessness. Often, these symptoms are attributed to patients' underlying physiological conditions; life-sustaining or life-prolonging treatments such as ventilators, invasive procedures, tubes, and monitoring lines; and noise and the fast-paced technological nature of the critical care environment. This, in turn, possibly increases length of stay and morbidity and challenges the recovery and healing of critically ill patients. Complementary therapies can be used as adjunctive therapies alongside pharmacological interventions and modalities. One complementary therapy with promise in critical care for improving symptoms of anxiety, pain, and sleeplessness is music. A review of current literature from Ovid MEDLINE, Cumulative Index to Nursing and Allied Health Literature, and PubMed was conducted to examine the evidence for the use of this complementary therapy in critical care settings. This review presents the evidence on effectiveness of music for the symptom management of anxiety, pain, and insomnia in critically ill adult patients. The evidence from this review supports music in symptom management of pain, insomnia, and anxiety in critically ill patients. This review provides practice recommendations, generates dialog, and promotes future research. This review is part I of a 2-part series that focuses on evidence for use of music, aromatherapy and guided imagery for improving anxiety, pain, and sleeplessness of patients in critically ill patients.

Patients with uninjured lungs may also benefit from lung-protective ventilator settings

Although mechanical ventilation is a life-saving strategy in critically ill patients and an indispensable tool in patients under general anesthesia for surgery, it also acts as a double-edged sword. Indeed, ventilation is increasingly recognized as a potentially dangerous intrusion that has the potential to harm lungs, in a condition known as ‘ventilator-induced lung injury’ (VILI). So-called ‘lung-protective’ ventilator settings aiming at prevention of VILI have been shown to improve outcomes in patients with acute respiratory distress syndrome (ARDS), and, over the last few years, there has been increasing interest in possible benefit of lung-protective ventilation in patients under ventilation for reasons other than ARDS. Patients without ARDS could benefit from tidal volume reduction during mechanical ventilation. However, it is uncertain whether higher levels of positive end-expiratory pressure could benefit these patients as well. Finally, recent evidence suggests that patients without ARDS should receive low driving pressures during ventilation.

Systems Medicine-Complexity Within, Simplicity Without

This paper presents a brief history of Systems Theory, progresses to Systems Biology, and its relation to the more traditional investigative method of reductionism. The emergence of Systems Medicine represents the application of Systems Biology to disease and clinical issues. The challenges faced by this transition from Systems Biology to Systems Medicine are explained; the requirements of physicians at the bedside, caring for patients, as well as the place of human-human interaction and the needs of the patients are addressed. An organ-focused transition to Systems Medicine, rather than a genomic-, molecular-, or cell-based effort is emphasized. Organ focus represents a middle-out approach to ease this transition and to maximize the benefits of scientific discovery and clinical application. This method manages the perceptions of time and space, the massive amounts of human- and patient-related data, and the ensuing complexity of information.

Different ventilation modes combined with ambroxol in the treatment of respiratory distress syndrome in premature infants

The aim of the present study was to compare the effectiveness of different modes of mechanical ventilation in combination with secretolytic therapy with ambroxol in premature infants with respiratory distress syndrome. Seventy-three premature infants with hyaline membrane disease (HMD) (stage III–IV), also known as respiratory distress syndrome, who were supported by mechanical ventilation in the neonatal intensive care unit (NICU) of Xuzhou Central Hospital, were involved in the present study, between January 2013 and February 2015. Forty cases were randomly selected and treated with high frequency oscillatory ventilation (HFOV), forming the HFOV group, whereas 33 cases were selected and treated with conventional mechanical ventilation (CMV), forming the CMV group. Patients in the two groups were administered ambroxol intravenously at a dosage rate of 30 mg/kg body weight at the beginning of the study. The present study involved monitoring the blood gas index as well as changes in the respiratory function index in the two groups. Additionally, the incidence of complications in the premature infants in the two groups was observed prior to and following the ventilation. Pulmonary arterial oxygen tension (PaO₂), the PaO₂/fraction of inspired oxygen (FiO₂) ratio, the oxygenation index [OI = 100 × mean airway pressure (MAP) × FiO₂/PaO₂], as well as the arterial/alveolar oxygen partial pressure ratio (a/APO₂) = PaO₂/(713 × FiO₂ partial pressure of carbon dioxide (PaCO₂)/0.8) of the patients in the HFOV group after 1, 12 and 24 h of treatment were significantly improved as compared to the patients of the CMV group. However, there was no significant difference between patients in the two groups with regard to the number of mortalities, complications such as pneumothorax, bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and the time of ventilation. In conclusion, combining HFOV with ambroxol secretolytic therapy is a more viable option, as the combined treatment resulted in significant improvements in arterial blood gas levels, oxygenation and the respiratory function of lungs in preterm infants.

Synergistic Effect of Hyperoxia and Biotrauma On Ventilator-Induced Lung Injury

Patients undergoing mechanical ventilation in intensive care units (ICUs) may develop ventilator-induced lung injury (VILI). Beside the high tidal volume (Vt) and plateau pressure (Pplat), hyperoxia is supposed to precipitate lung injury. Oxygen toxicity is presumed to occur at levels of fraction of inspired oxygen (FiO2) exceeding 0.40. The exposure time to hyperoxia is certainly very important and patients who spend extended time on mechanical ventilation (MV) are probably more exposed to severe hyperoxic acute lung injury (HALI). Together, hyperoxia and biotrauma (release of cytokines) have a synergistic effect and can induce VILI. In the clinical practice, the reduction of FiO2 to safe levels through the appropriate use of the positive end expiratory pressure (PEEP) and the alignment of mean airway pressure is an appropriate goal. The strategy for lung protective ventilation must include setting up FiO2 to a safe level that is accomplished by using PaO2/FiO2 ratio with a lower limit of FiO2 to achieve acceptable levels of PaO2, which will be safe for the patient without local (lungs) or systemic inflammatory response. The protocol from the ARDS-net study is used for ventilator setup and adjustment. Cytokines (IL-1, IL-6, TNFα and MIP-2) that are involved in the inflammatory response are determined in order to help the therapeutic approach in counteracting HALI. Computed tomography findings reflect the pathological phases of the diffuse alveolar damage. At least preferably the lowest level of FiO2 should be used in order to provide full lung protection against the damage induced by MV.

High Positive End-Expiratory Pressure Is Associated with Improved Survival in Obese Patients with Acute Respiratory Distress Syndrome

BACKGROUND

In acute respiratory distress syndrome, minimizing lung injury from repeated collapse and reopening of alveoli by applying a high positive end-expiratory pressure improves oxygenation without influencing mortality. Obesity causes alveolar atelectasis, thus suggesting that a higher positive end-expiratory pressure might be more protective among the obese. We hypothesized that the effect of applying a high positive end-expiratory pressure on mortality from acute respiratory distress syndrome would differ by obesity status.

METHODS

This was a retrospective analysis of 505 patients from the Assessment of Low tidal Volume and elevated End-expiratory volume to Obviate Lung Injury Trial, a multicenter randomized trial that compared a higher vs a lower positive end-expiratory pressure ventilatory strategy in acute respiratory distress syndrome. We examined the relationship between positive end-expiratory pressure strategy and 60-day mortality stratified by obesity status.

RESULTS

Among obese patients with acute respiratory distress syndrome, those assigned to a high positive end-expiratory pressure strategy experienced lower mortality compared with those assigned to a low strategy (18% vs 32%; P = .04). Among the nonobese, those assigned to high positive end-expiratory pressure strategy experienced similar mortality with those assigned to low strategy (34% vs 23%; P = .13). Multivariate analysis demonstrated an interaction between obesity status and the effect of positive end-expiratory pressure strategy on mortality (P <.01).

CONCLUSIONS

Ventilation with higher levels of positive end-expiratory pressure was associated with improved survival among the subgroup of patients with acute respiratory distress syndrome who are obese.

[Clinical effects of different ways of mechanical ventilation combined with pulmonary surfactant in treatment of acute lung injury/acute respiratory distress syndrome in neonates: a comparative analysis]

OBJECTIVE

To compare the therapeutic effects of high-frequency oscillatory ventilation+pulmonary surfactant (HFOV+PS), conventional mechanical ventilation+pulmonary surfactant (CMV+PS), and conventional mechanical ventilation (CMV) alone for acute lung injury/acute respiratory distress syndrome (ALI/ARDS) in neonates.

METHODS

A total of 136 neonates with ALI/ARDS were enrolled, among whom 73 had ALI and 63 had ARDS. They were divided into HFOV+PS group (n=45), CMV+PS group (n=53), and CMV group (n=38). The neonates in the first two groups were given PS at a dose of 70-100 mg/kg. The partial pressure of oxygen (PaO₂), partial pressure of carbon dioxide (PaCO₂), PaO₂/fraction of inspired oxygen (FiO₂), oxygenation index (OI), and respiratory index (RI) were measured at 0, 12, 24, 48, and 72 hours of mechanical ventilation.

RESULTS

At 12, 24, and 48 hours of mechanical ventilation, the HFOV+PS group had higher PaO₂ and lower PaCO₂ than the CMV+PS and CMV groups (P<0.05). At 12, 24, 48, and 72 hours of mechanical ventilation, the HFOV+PS group had higher PaO₂/FiO₂ and lower OI and RI than the CMV+PS and CMV groups (P<0.05). The HFOV+PS group had shorter durations of mechanical ventilation and oxygen use than the CMV+PS and CMV groups (P<0.05). There were no significant differences in the incidence rates of air leakage and intracranial hemorrhage and cure rate between the three groups.

CONCLUSIONS

In neonates with ALI/ARDS, HFOV combined with PS can improve pulmonary function more effectively and shorten the durations of mechanical ventilation and oxygen use compared with CMV+PS and CMV alone. It does not increase the incidence of complications.

[Pulmonary complications associated with mechanical ventilation in neonates]

BACKGROUND

To determine the incidence of0 associated with mechanical ventilation in patients admitted to a service in a second level hospital NICU.

METHODS

Retrospective analytical study records of newborns admitted to NICU room and receiving mechanical ventilation in a secondary hospital health care. Demographic data, of mechanical ventilation, intubation and complications reported in the clinical record were collected and analyzed in SPSS 20.

RESULTS

53 patients selected a total of 40 complications found. The annual incidence of pulmonary complications associated with mechanical ventilation in the area of service neonatology NICU, at a second level hospital at Sonora was 49.05% (95% CI 0.35 to 0.62). The most frequent pulmonary complications were atelectasis 35%, pneumonia 27.5%, pneumothorax 15%, bronchopulmonary dysplasia 15%, pneumomediastinum 15% and pulmonary hemorrhage 2.5%.

CONCLUSIONS

The presentation of pulmonary complications secondary to mechanical ventilation in neonatal patients is similar to that reported in developing countries. Atelectasis is the most common pulmonary complication in neonatal patients undergoing mechanical ventilation.

Early Mobilization of Mechanically Ventilated Patients

Critically ill patients requiring mechanical ventilation are least likely to be mobilized and, as a result, are at-risk for prolonged complications from weakness. The use of bed rest and sedation when caring for mechanically ventilated patients is likely shaped by historical practice; however, this review demonstrates early mobilization, with little to no sedation, is possible and safe. Assessing readiness for mobilization in context of progressing patients from passive to active activities can lead to long-term benefits and has been achievable with resource-efficient implementations and team work.

The usability of ventilators: a comparative evaluation of use safety and user experience

Background

The design complexity of critical care ventilators (CCVs) can lead to use errors and patient harm. In this study, we present the results of a comparison of four CCVs from market leaders, using a rigorous methodology for the evaluation of use safety and user experience of medical devices.

Methods

We carried out a comparative usability study of four CCVs: Hamilton G5, Puritan Bennett 980, Maquet SERVO-U, and Dräger Evita V500. Forty-eight critical care respiratory therapists participated in this fully counterbalanced, repeated measures study. Participants completed seven clinical scenarios composed of 16 tasks on each ventilator.

Use safety was measured by percentage of tasks with use errors or close calls (UE/CCs). User experience was measured by system usability and workload metrics, using the Post-Study System Usability Questionnaire (PSSUQ) and the National Aeronautics and Space Administration Task Load Index (NASA-TLX).

Results

Nine of 18 post hoc contrasts between pairs of ventilators were significant after Bonferroni correction, with effect sizes between 0.4 and 1.09 (Cohen’s d). There were significantly fewer UE/CCs with SERVO-U when compared to G5 (p = 0.044) and V500 (p = 0.020). Participants reported higher system usability for G5 when compared to PB980 (p = 0.035) and higher system usability for SERVO-U when compared to G5 (p < 0.001), PB980 (p < 0.001), and V500 (p < 0.001). Participants reported lower workload for G5 when compared to PB980 (p < 0.001) and lower workload for SERVO-U when compared to PB980 (p < 0.001) and V500 (p < 0.001). G5 scored better on two of nine possible comparisons; SERVO-U scored better on seven of nine possible comparisons. Aspects influencing participants’ performance and perception include the low sensitivity of G5’s touchscreen and the positive effect from the quality of SERVO-U’s user interface design.

Conclusions

This study provides empirical evidence of how four ventilators from market leaders compare and highlights the importance of medical technology design. Within the boundaries of this study, we can infer that SERVO-U demonstrated the highest levels of use safety and user experience, followed by G5. Based on qualitative data, differences in outcomes could be explained by interaction design, quality of hardware components used in manufacturing, and influence of consumer product technology on users’ expectations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1431-1) contains supplementary material, which is available to authorized users.

Perioperative ventilatory strategies in cardiac surgery

Recent data promote the utilization of prophylactic protective ventilation even in patients without acute respiratory distress syndrome (ARDS), and especially after cardiac surgery. The implementation of specific perioperative ventilatory strategies in patients undergoing cardiac surgery can improve both respiratory and extra-pulmonary outcomes. Protective ventilation is not limited to tidal volume reduction. The major components of ventilatory management include assist-controlled mechanical ventilation with low tidal volumes (6-8 mL kg(-1) of predicted body weight) associated with higher positive end-expiratory pressure (PEEP), limitation of fraction of inspired oxygen (FiO2), ventilation maintenance during cardiopulmonary bypass, and finally recruitment maneuvers. In order for such strategies to be fully effective, they should be integrated into a multimodal approach beginning from the induction and continuing over the postoperative period.

Reducing the burden of acute respiratory distress syndrome: the case for early intervention and the potential role of the emergency department

The mortality for acute respiratory distress syndrome (ARDS) remains unacceptably high. Success in clinical trials has been limited, resulting in a lack of effective therapies to treat the syndrome. The projected increase in mechanically ventilated patients and global need for critical care services suggests that the clinical and research landscape in ARDS can no longer be confined to the intensive care unit. A demonstrable minority of patients present to the emergency department (ED) with ARDS, and ARDS onset typically occurs shortly after intensive care unit admission. Furthermore, the ED is an entry point for many of the highest-risk patients for ARDS development and progression. These facts, combined with prolonged lengths of stay in the ED, suggest that the ED could represent a window of opportunity for treatment and preventive strategies, as well as clinical trial enrollment. This review aims to discuss some of the potential strategies that may prevent or alter the trajectory of ARDS, with a focus on the potential role the ED could play in reducing the burden of this syndrome.

Model-based setting of inspiratory pressure and respiratory rate in pressure-controlled ventilation

Mechanical ventilation carries the risk of ventilator-induced-lung-injury (VILI). To minimize the risk of VILI, ventilator settings should be adapted to the individual patient properties. Mathematical models of respiratory mechanics are able to capture the individual physiological condition and can be used to derive personalized ventilator settings. This paper presents model-based calculations of inspiration pressure (pI), inspiration and expiration time (tI, tE) in pressure-controlled ventilation (PCV) and a retrospective evaluation of its results in a group of mechanically ventilated patients. Incorporating the identified first order model of respiratory mechanics in the basic equation of alveolar ventilation yielded a nonlinear relation between ventilation parameters during PCV. Given this patient-specific relation, optimized settings in terms of minimal pI and adequate tE can be obtained. We then retrospectively analyzed data from 16 ICU patients with mixed pathologies, whose ventilation had been previously optimized by ICU physicians with the goal of minimization of inspiration pressure, and compared the algorithm's 'optimized' settings to the settings that had been chosen by the physicians. The presented algorithm visualizes the patient-specific relations between inspiration pressure and inspiration time. The algorithm's calculated results highly correlate to the physician's ventilation settings with r = 0.975 for the inspiration pressure, and r = 0.902 for the inspiration time. The nonlinear patient-specific relations of ventilation parameters become transparent and support the determination of individualized ventilator settings according to therapeutic goals. Thus, the algorithm is feasible for a variety of ventilated ICU patients and has the potential of improving lung-protective ventilation by minimizing inspiratory pressures and by helping to avoid the build-up of clinically significant intrinsic positive end-expiratory pressure.