Various Modes Of Mechanical Ventilation Research Articles

Post-insufflation diaphragm contractions in patients receiving various modes of mechanical ventilation

BackgroundDuring mechanical ventilation, post-insufflation diaphragm contractions (PIDCs) are non-physiologic and could be injurious. PIDCs could be frequent during reverse-triggering, where diaphragm contractions follow the ventilator rhythm. Whether PIDCs happens with different modes of assisted ventilation is unknown. In mechanically ventilated patients with hypoxemic respiratory failure, we aimed to examine whether PIDCs are associated with ventilator settings, patients’ characteristics or both.MethodsOne-hour recordings of diaphragm electromyography (EAdi), airway pressure and flow were collected once per day for up to five days from intubation until full recovery of diaphragm activity or death. Each breath was classified as mandatory (without-reverse-triggering), reverse-triggering, or patient triggered. Reverse triggering was further subclassified according to EAdi timing relative to ventilator cycle or reverse triggering leading to breath-stacking. EAdi timing (onset, offset), peak and neural inspiratory time (Tineuro) were measured breath-by-breath and compared to the ventilator expiratory time. A multivariable logistic regression model was used to investigate factors independently associated with PIDCs, including EAdi timing, amplitude, Tineuro, ventilator settings and APACHE II.ResultsForty-seven patients (median[25%-75%IQR] age: 63[52–77] years, BMI: 24.9[22.9–33.7] kg/m2, 49% male, APACHE II: 21[19–28]) contributed 2 ± 1 recordings each, totaling 183,962 breaths. PIDCs occurred in 74% of reverse-triggering, 27% of pressure support breaths, 21% of assist-control breaths, 5% of Neurally Adjusted Ventilatory Assist (NAVA) breaths. PIDCs were associated with higher EAdi peak (odds ratio [OR][95%CI] 1.01[1.01;1.01], longer Tineuro (OR 37.59[34.50;40.98]), shorter ventilator inspiratory time (OR 0.27[0.24;0.30]), high peak inspiratory flow (OR 0.22[0.20;0.26]), and small tidal volumes (OR 0.31[0.25;0.37]) (all P ≤ 0.008). NAVA was associated with absence of PIDCs (OR 0.03[0.02;0.03]; P < 0.001). Reverse triggering was characterized by lower EAdi peak than breaths triggered under pressure support and associated with small tidal volume and shorter set inspiratory time than breaths triggered under assist-control (all P < 0.05). Reverse triggering leading to breath stacking was characterized by higher peak EAdi and longer Tineuro and associated with small tidal volumes compared to all other reverse-triggering phenotypes (all P < 0.05).ConclusionsIn critically ill mechanically ventilated patients, PIDCs and reverse triggering phenotypes were associated with potentially modifiable factors, including ventilator settings. Proportional modes like NAVA represent a solution abolishing PIDCs.

Evolution of inspiratory muscle function in children during mechanical ventilation

BackgroundThere is no universally accepted method to assess the pressure-generating capacity of inspiratory muscles in children on mechanical ventilation (MV), and no study describing its evolution over time in this population.MethodsIn this prospective observational study, we have assessed the function of the inspiratory muscles in children on various modes of MV. During brief airway occlusion maneuvers, we simultaneously recorded airway pressure depression at the endotracheal tube (ΔPaw, force generation) and electrical activity of the diaphragm (EAdi, central respiratory drive) over five consecutive inspiratory efforts. The neuro-mechanical efficiency ratio (NME, ΔPaw/EAdimax) was also computed. The evolution over time of these indices in a group of children in the pediatric intensive care unit (PICU) was primarily described. As a secondary objective, we compared these values to those measured in a group of children in the operating room (OR).ResultsIn the PICU group, although median NMEoccl decreased over time during MV (regression coefficient − 0.016, p = 0.03), maximum ΔPawmax remained unchanged (regression coefficient 0.109, p = 0.50). Median NMEoccl at the first measurement in the PICU group (after 21 h of MV) was significantly lower than at the only measurement in the OR group (1.8 cmH2O/µV, Q1–Q3 1.3–2.4 vs. 3.7 cmH2O/µV, Q1–Q3 3.5–4.2; p = 0.015). Maximum ΔPawmax in the PICU group was, however, not significantly different from the OR group (35.1 cmH2O, Q1–Q3 21–58 vs. 31.3 cmH2O, Q1–Q3 28.5–35.5; p = 0.982).ConclusionsThe function of inspiratory muscles can be monitored at the bedside of children on MV using brief airway occlusions. Inspiratory muscle efficiency was significantly lower in critically ill children than in children undergoing elective surgery, and it decreased over time during MV in critically ill children. This suggests that both critical illness and MV may have an impact on inspiratory muscle efficiency.

Dual infection: Dengue fever with Legionella pneumonia complicated with acute kidney injury and rhabdomyolysis

Background: Concurrent infection of dengue fever with legionella pneumonia is relatively rare occurrence as there is no case report documented in literatures. Treating dengue fever with bacterial infection has been an emerging challenge for physician. Legionella pneumophila is a common, usually underreported and undiagnosed cause of community acquired pneumonia which can lead to significant morbidity and mortality. We present a case of previously healthy man diagnosed as dengue fever with legionella pneumonia complicated with severe acute respiratory distress syndrome, acute renal failure and rhabdomyolysis. Case Description: A 42 y old gentleman with underlying bronchial asthma presented to emergency department with three days history of fever, nonproductive cough for two d with shortness of breath and chest discomfort. He was febrile, tachypneic and tachycardic. His blood pressure was 150/80 mmHg and saturating at 95% on room air. Crepitations were present on the right lower zone. Reviews of other system unremarkable. His full blood count showed leucopenia with thrombocytopenia. His Urea and creatinine were high. Creatine kinase was tremendously high reaches 34000 U/L indicates rhabdomyolysis. Arterial blood gas showed type 1 respiratory failure. Chest xray revealed consolidation over right basal with right sided pleural effusion. His rapid dengue serology noted NS1 antigen positive and dengue PCR revealed dengue genotype 1. He was placed on mechanical ventilation as respiratory distress worsened with hypoxemia. Empirically intravenous ceftriaxone was given to cover for pneumonia. However, he was rapidly deteriorated into septic shock. Subsequently noted that Legionella pneumophila Urinary Antigen was positive. Thus, azithromycin was prescribed. He has improved dramatically over the next 48 h and became hemodynamically stable. Discussion: Legionnaires disease was diagnosed as the cause of the clinical spectrum described. Acute kidney injury and rhabdomyolysis gradually improved after azithromycin commencement. In this case as the patient had dengue fever with legionella pneumonia, the cause for pleural effusion became a challenging part for physician. Treatment with appropriate fluid resuscitation, antibiotics and various modes of mechanical ventilation in the intensive care unit were successful. Conclusion: The presentation of progressively worsening respiratory distress or sepsis with dengue fever should raise the treating physician's suspicion of concurrent infection to reduce dengue fever associated mortality.

"Current concepts in assisted mechanical ventilation in the neonate" - Part 2: Understanding various modes of mechanical ventilation and recommendations for individualized disease-based approach in neonates.

Mechanical ventilation is a lifesaving intervention in critically ill preterm and term neonates. However, it has the potential to cause significant damage to the lungs resulting in long-term complications. Understanding the pathophysiological process and having a good grasp of the basic concepts of conventional and high-frequency ventilation is essential for any medical or allied healthcare practitioner involved in the neonates’ respiratory management. This review aims to describe the various types and modes of ventilation usually available in neonatal units. It also describes recommendations of an individualized disease-based approach to mechanical ventilation strategies implemented in the authors’ institutions.

Ultrasonographic Evaluation of Diaphragm Thickness During Mechanical Ventilation in Intensive Care Patients.

Mechanical ventilation is associated with atrophy and weakness of the diaphragm. Ultrasound is an easy noninvasive way to track changes in thickness of the diaphragm. To validate ultrasound as a means of tracking thickness of the diaphragm in patients undergoing mechanical ventilation by evaluating interobserver and interoperator reliability and to collect initial data on the relationship of mode of ventilation to changes in the diaphragm. Daily ultrasound images of the quadriceps and the right side of the diaphragm were acquired in 8 critically ill patients receiving various modes of mechanical ventilation. Thickness of the diaphragm and the quadriceps was measured, and changes with time were noted. Interoperator and interobserver reliability were measured. Intraclass correlation coefficients between operators and between observers for thickness of the diaphragm and quadriceps were greater than 0.95, indicating excellent interoperator and interobserver reliability. Patients receiving assist-control ventilation (n = 4) showed a mean decline in diaphragm thickness of 4.7% per day. Patients receiving pressure support ventilation (n = 8) showed a mean increase in diaphragm thickness of 1.5% per day. Quadriceps thickness declined in all participants (n = 8) at a mean rate of 2.0% per day. Use of ultrasound to measure thickness of the diaphragm in 8 intensive care patients undergoing various modes of mechanical ventilation was feasible and yielded reproducible results. Ultrasound tracking of changes in thickness of the diaphragm in this small sample indicated that the thickness decreased during assist-control mode and increased during pressure support mode.

Effects of Various Modes of Mechanical Ventilation in Normal Rats

Recent studies in healthy mice and rats have reported that positive pressure ventilation delivered with physiological tidal volumes at normal end-expiratory volume worsens lung mechanics and induces cytokine release, thus suggesting that detrimental effects are due to positive pressure ventilation per se. The aim of this study in healthy animals is to assess whether these adverse outcomes depend on the mode of mechanical ventilation. Rats were subjected to 4 h of spontaneous, positive pressure, and whole-body or thorax-only negative pressure ventilation (N = 8 per group). In all instances the ventilatory pattern was that of spontaneous breathing. Lung mechanics, cytokines concentration in serum and broncho-alveolar lavage fluid, lung wet-to-dry ratio, and histology were assessed. Values from eight animals euthanized shortly after anesthesia served as control. No evidence of mechanical ventilation-dependent lung injury was found in terms of lung mechanics, histology, or wet-to-dry ratio. Relative to control, cytokine levels and recruitment of polymorphonuclear leucocytes increased slightly, and to the same extent with spontaneous, positive pressure, and whole-body negative pressure ventilation. Thorax-only negative pressure ventilation caused marked chest and lung distortion, reversible increase of lung elastance, and higher polymorphonuclear leucocyte count and cytokine levels. Both positive and negative pressure ventilation performed with tidal volumes and timing of spontaneous, quiet breathing neither elicit an inflammatory response nor cause morpho-functional alterations in normal animals, thus supporting the notion of the presence of a critical volume threshold above which acute lung injury ensues. Distortion of lung parenchyma can induce an inflammatory response, even in the absence of volotrauma.

Sleep and the ICU

Disturbed sleep is common in critical illness, not only during early phases of treatment in an intensive care unit (ICU) but also during later stages of recovery after ICU discharge. While sleep quality during critical illness is usually not a primary concern of intensivists, disrupted sleep can impede recovery and has been associated with immune system dysfunction, impaired wound healing, and adverse neurological and psychological outcomes (1). The noise and lighting of the ICU environment, frequent patient-provider interactions, and critical care procedures all profoundly impact sleep quality and continuity in critically ill patients. Various sedative medications and various modes of mechanical ventilation can also affect sleep. This article will review (1) sleep disruption and its clinical manifestations in the ICU patient, (2) the effects of the ICU environment and routine critical care on sleep disturbances, (3) the biological consequences of critical illness on sleep and circadian rhythms, and how sleep deprivation (SD) affects the immune system, (4) iatrogenic disturbances of sleep in the ICU patient (e.g. commonly used sedatives, mechanical ventilation), and (5) sleep during recovery after critical illness.

Severe Legionnaires disease complicated by multi-organ dysfunction in a previously healthy patient: a case report

A case of a previously healthy lady with community-acquired pneumonia who progressed to severe acute respiratory distress syndrome, acute renal failure, disseminated intravascular coagulation and sepsis is reported. Treatment with antibiotics and various modes of mechanical ventilation in the intensive care unit were successful. A urinary legionella antigen test was positive for Legionella pneumophila.

Advantage of spontaneous breathing in patients with respiratory failure

The fact that different modalities of mechanical ventilation are associated with a number of serious side effects and risks and can influence the clinical outcome of patients, the various modes of mechanical ventilation have, over the past ten years, been the subject of a wide variety of scientific studies. Many of these modalities are designed for partial ventilatory support, which might reflect the complexity of the issue of patient’s ventilator interactions when spontaneous breathing activity is present, compared to controlled mechanical ventilation. Spontaneous breathing modes during mechanical ventilation may integrate intrinsic feedback mechanisms that should help prevent ventilator- induced lung injury and improve synchrony between the ventilator and the patient’s demand. The improvements in pulmonary gas exchange, systemic blood flow, and oxygen supply to the tissue that have been observed when spontaneous breathing has been maintained during mechanical ventilation are reflected in the clinical improvement in the patient’ s condition. It is the aim of this article to review the effects of preserved spontaneous breathing activity during mechanical ventilation in patients with acute respiratory failure.

Effect of the inspiratory flow pattern on inspiration/expiration transition of lung vibrations in mechanically ventilated patients

Mechanical ventilation can be performed using different inspiratory flow patterns. We used vibration response imaging (VRI) technology to ascertain the intensity of lung vibration with different inspiratory flow patterns during various modes of mechanical ventilation.

Severe Sepsis and Acute Respiratory Distress Syndrome From Community-Acquired Legionella Pneumonia: Case Report

A case of a young man with community-acquired pneumonia, severe acute respiratory distress syndrome, and sepsis is reported. Treatment with antibiotics and various modes of mechanical ventilation in the intensive care unit were unsuccessful. A urinary legionella antigen test was positive for Legionella pneumophila.

Newer experience with CPAP

Progress in neonatal intensive care is closely linked to improvements in the management of respiratory failure in small infants. Current modalities of ventilatory assistance range from more benign continuous positive airway pressure (CPAP) to various modes of mechanical ventilation (including high frequency ventilation). The advent of less invasive methods of delivering CPAP has permitted earlier treatment of infants with respiratory distress syndrome and avoided the need for mechanical ventilation. Children's Hospital of New York (Columbia University) places all spontaneously breathing infants on nasal prong CPAP as the first mode of respiratory support. The early initiation of nasal prong CPAP in combination with a tolerance to elevated PCO2 levels has reduced the incidence of chronic lung disease to <5% in infants weighing less than 1500g. This report will present an historical review and summarize the experience with CPAP at Columbia and other centres. In addition, it reviews the clinical applications and physiological effects of CPAP in preterm infants with respiratory distress syndrome.

Ventilatory Strategies for the Critically III Infant and Child

As newer modes of mechanical ventilation and adjuncts to ventilation continue to be developed and studied, pediatric critical care practitioners are going to have many exciting options for the treatment of the critically ill infant and child. All who provide care to these critically ill patients must continue to evaluate these varied ventilatory strategies.

Airway management and ventilation of infants and children

Advances in new techniques of infant respiratory function testing and resultant new findings in respiratory mechanics have contributed importantly to recent progress in the management of airways and the ventilation of infants and children. As clinical application of the laryngeal mask airway in pediatric anesthesia increases, controversy over the safety of this technique with positive pressure ventilation continues. Recent progress in the ventilation of pediatric patients in neonatal and pediatric intensive care settings is reviewed, including liquid breathing, inhaled nitric oxide, and various modes of mechanical ventilation.

Current trends in mechanical ventilation

It is increasingly evident that there is little data available to compare the use of various modes of mechanical ventilation or to assess their application. It is difficult to compare the new modes of mechanical ventilation with the conventional modes because of a similar lack of clinical data. The challenge for future research in the area of ventilator technology is to generate controlled clinical studies to support its application. With the increased impact of financial constraints on healthcare, research will also need to examine the economic issues related to the application of newer modes of mechanical ventilation. The critical care nurse will be faced with the continued challenge of being knowledgeable regarding the current trends in ventilatory support and their potential advantages and disadvantages, while keeping in perspective those areas where clinical research is lacking. Possibilities for future nursing research related to mechanical ventilation are endless. The application and refinement of assessment parameters to evaluate the impact of nursing interventions on mechanically ventilated patients should be a key focus. The growing use of SVO2 monitoring in conjunction with other assessment parameters may prove to be useful tools to measure the impact of interventions such as suctioning, positioning, muscle reconditioning, weaning techniques, and comfort measures on mechanically ventilated patients.

Effect of ventilation on surface forces in excised dogs' lungs.

Effect of ventilation on surface forces in excised dogs' lungs.