Patient effort at a glance

A: Patient with little effort. Top: Volume Controlled Ventilation: airway pressure in cmH2O in yellow, constant flow in L/min in pink. Middle: Pressure controlled ventilation: airway pressure in cmH2O in yellow, decelerating flow in L/min in pink. Bottom: Esophageal pressure in cmH2O. B: Patient with high effort. Top: Volume Controlled Ventilation: airway pressure with convex negative deflection during trigger and first half of inspiration (blue arrow). Middle: Pressure controlled ventilation: airway pressure with negative deflection during the trigger (yellow arrow) and slight convex deflection (green arrow), concave deflection in the flow (orange arrow). Bottom: Convex deflection in esophageal pressure (grey arrow).

Calming the Storm: A review of corticosteroid use in severely ill COVID-19 patients on mechanical ventilation

The importance of corticosteroids in the therapy of COVID-19 has been controversial. However, as the world develops a better understanding regarding the pathophysiology of COVID-19, we are realizing that suppressing the host immune response may reduce lung inflammation preventing further complications. In addition, more high-quality randomized controlled trials, meta-analysis, and review articles are being published discussing the role of corticosteroids. Majority of these studies concluded that corticosteroids are beneficial for hospitalized severely ill COVID-19 patients requiring supplemental oxygen. To date, therapeutic guidelines for COVID-19 patients recommend dexamethasone or other alternative corticosteroids, including methylprednisolone, hydrocortisone, or prednisone, as a treatment choice for severely ill COVID-19 patients. This review will discuss the pharmacology, mechanism of action, pharmacodynamics, pharmacokinetics, and benefits of corticosteroids in COVID-19 patients, and review current published clinical evidence on corticosteroids. Keywords: Corticosteroids, COVID-19, ARDS

Effect of Trendelenburg position during prone ventilation in fifteen COVID-19 patients. Observational study

Background Prone position ventilation has shown to improve oxygenation and mortality in severe ARDS. The data of prone position ventilation during severe ARDS secondary to COVID-19 have shown similar benefit in oxygenation and mortality. Usually, patient placed in prone position are placed flat or in reverse Trendelenburg positioning to decrease risk of aspiration and abdominal girth compressing the chest. To date, no studies are available to compare the effects of positioning the bed in different angles during the prone position ventilation. Methods An observational study in fifteen patients with severe ARDS secondary to COVID-19 who were placed in the prone position for the first time. All the patients were sedated and chemically paralyzed with no spontaneous effort. All patients were ventilated with the pressure-controlled mode with set PEEP according to the pressure-volume curves. Five patients had esophageal balloon manometry to estimate pleural pressures and trans-pulmonary pressures. Patients were initially placed in reverse Trendelenburg position and later in Trendelenburg position. Tidal volume and respiratory compliance were observed for 30 minutes after bed positioning has been achieved. Tidal volume and total respiratory compliance in both Trendelenburg and reverse Trendelenburg position were compared. Ventilator settings were not changed during the observation. No patients were suspected of increased intra-cranial or intra-ocular pressures. T-test was done to compare the values. Results Tidal volume significantly increased by 80.26 ± 23.4 ml/breath (95% CI 37.7 - 122.9) from 391.3 ± 52.7 to 471.6 ± 60.9 (20.5%) P 0.001. The respiratory system compliance significantly increased by 4.9 ml/cmH2O (95% CI 1.4 - 8.4) from 34.6 ± 4.7 to 39.5 ± 4.6 (14%) P 0.001. Of the five patients with esophageal balloon, the lung compliance significantly increased by 16.7 ml/cmH2O (95% CI 12.8 – 20.6) from 66.6 ± 1.7 to 83.3 ± 3.3 (25%) P 0.001. The chest wall compliance had small but non-significant increase by 1.5 ml/cmH2O (95% CI -1.3 – 4.3) from 65 ± 1.4 to 66.5 ± 2.3 (2%) P 0.085. Conclusion In this study, statistically significant increase in tidal volume, lung and respiratory system compliance were observed in patients placed in the Trendelenburg position during prone position ventilation. The results reflect the effect of body positioning during prone position ventilation. These effects may be the reflection of altered ventilation distribution throughout the lungs and change in pleural pressure as well as trans-pulmonary pressure during body positioning. More studies need to be done to confirm and examine this phenomenon. Precautions should be taken as this maneuver can increase the intra-cranial and intra-ocular pressures. Keywords: COVID-19, Trendelenburg, Reverse Trendelenburg, ARDS

History of Intermittent Mandatory Ventilation prior to 1972. Part one. Special Article

Medical history is often overlooked as advances keep moving forward. Seldom is it that advances in medicine are truly new, unique ideas, but rather built on ideas that have been considered before. Even our latest developments will become history or forgotten as science and medicine advance. This history of intermittent mandatory ventilation (IMV) is a two-part article in which the first part attempts to show that the concepts and apparatus that involve the now common mode of ventilation have been considered and described for nearly 200 years, if not earlier. This older history is not brought forward to diminish what has been done in the last 50 years, but to enhance awareness of how ideas and even mechanical ventilators change over time. The second part will describe how those ideas and mechanics changed into what we now call IMV in its many forms. Keywords: Intermittent Mandatory Ventilation, IMV, History of mechanical ventilation

A review of hospital based ventilator malfunctions reported to the FDA in 2021

Ventilator care is synonymous with Intensive care. These devices are electromechanical and as such can fail. Most failures are without patient incident, injury, and harm. The FDA requires manufacturers who learn of malfunction, injury or death while operating their product to report to the agency via the Manufacturer and User Facility Device Experience database. I reviewed 500 recent events reported to the FDA and found an increasing trend from 2020 to 2021 in hospital ventilator malfunction reports. Examination of these reports is critical to assuring quality ventilator care. The author concluded that intensive training on the device characteristics and feature and a more rigorous examination of ventilator performance between patients may assist in reducing device malfunctions. Keywords: Mechanical ventilation, Ventilator malfunction, FDA

Alveolar air leak and paraseptal emphysema in severe COVID-19 disease

Background Corona virus 2019 (COVID-19) pandemic spread in the world as a great medical crisis. Its pathophysiology, manifestations, complications, and management are not completely defined, yet. In this study frequency of alveolar air leak in critically ill COVID-19 subjects is explored. Methods A total of 820 critically ill COVID-19 subjects who admitted with respiratory insufficiency to ICUs of Sina University Hospital from March 2020 to June 2021 were included. All their chest x ray (CXR) and Computed tomography (CT) of chest were reviewed. All alveolar air leak episodes (pneumothorax, pneumomediastinum, pneumopericardium, subcutaneous emphysema) suspected films reviewed by attending intensivist and radiologist. Results Of the 820 ill COVID-19 subjects in ICUs, 492(60%) were male, and 328 (40%) were female. The Mean age of 820 subjects was 60.84 + 16.82. 584 (71.22%) of subjects were non-intubated, and 236 (28.78%) were intubated. Alveolar air leak occurred in 98 (11.95%) of subjects. Alveolar air leak episodes include pneumothorax in 26 (3.17%), subcutaneous emphysema in 72 (8.78%), pneumomediastinum in 9 (1.10%), and pneumopericardium in 1 (0.12%) of subjects. The mean age in non-intubated subjects was 59.65 + 16.84, and for intubated subjects was 63 + 16.42. There was a significant difference in age between the groups who get intubated, versus not intubated P 0.001. Of the 584 non-intubated subjects, 31 (5.31%) had subcutaneous emphysema, of the 236 intubated subjects, 41 (17.37%) had subcutaneous emphysema. Difference between groups was statistically significant, P <0.001. When we compared intubated and non-intubated patients in case of total numbers of alveolar air leak episodes, the difference was statistically significant P <0.001. Conclusion According to this study, intubation was implemented more in older patients. Also, invasive ventilation was significantly associated with subcutaneous emphysema and total number of alveolar air leak episodes. In every patient with exaggeration of hypoxia, dyspnea or chest pain, pneumothorax should be kept in mind as a differential diagnosis. Keywords: COVID-19; Respiratory failure; Alveolar air leak; Paraseptal emphysema

Four Truths of Mechanical Ventilation and the Ten-Fold Path to Enlightenment

The Four Truths 1. The truth of confusion 2. The truth of the origin of confusion 3. The truth of the cessation of confusion 4. The truth of the path leading to the cessation of confusion The 10-Fold Path 1. A breath is one cycle of positive flow (inspiration) and negative flow (expiration) defined in terms of the flow-time curve. 2. A breath is assisted if the ventilator does work on the patient. 3. A ventilator assists breathing using either pressure control or volume control based on the equation of motion for the respiratory system. 4. Breaths are classified by the criteria that trigger (start) and cycle (stop) inspiration 5. Trigger and cycle events can be initiated by the patient or the machine. 6. Breaths are classified as spontaneous or mandatory based on both the trigger and cycle events. 7. There are 3 breath sequences: Continuous mandatory ventilation (CMV), Intermittent Mandatory Ventilation (IMV), and Continuous Spontaneous Ventilation (CSV). 8. There are 5 basic ventilatory patterns: VC-CMV, VC-IMV, PC-CMV, PC-IMV, and PC-CSV: 9. Within each ventilatory pattern there are several variations that can be distinguished by their targeting scheme(s). 10. A mode of ventilation is classified according to its control variable, breath sequence, and targeting scheme(s). Keywords: Breath. Trigger, Cycle, Breath sequences, Ventilatory patterns, Mode of ventilation

Glossary and definitions of terms used in mechanical ventilation

Review of the most common terms used in mechanical ventilation and their definitions.

Volumetric Capnometry, more than end-tidal carbon dioxide

Monitoring the exhaled caron dioxide pressure, known as end-tidal CO2 (ETCO2) has become the standard of care during anesthesia, intensive care units, and during cardiac arrest resuscitation. However, volumetric capnometry provides much more useful information other than the ETCO2.

Mechanical ventilation modes utilization. An international survey of clinicians

Background There has been an exponential increase in modes of mechanical ventilation over the last couple decades. With this increase, there have been paucity of evidence of which mode is superior to others or much guidance to use a mode in different disease status causing respiratory failure. Methods: An international survey of six questions was posted on the “society of mechanical ventilation” website and advertised on social media over the period of four months. This is a descriptive study, results are presented in two different ways. First as the total modes used and secondly, per the geographical areas as the preferred mode, mode used mostly in ARDS, COPD, and Spontaneous weaning trials. Results: Conventional older modes, Volume-controlled and Pressure-controlled ventilation were used significantly more in general and in different disease states irrespective of geographical location. Four other modes were used almost equally in all disease states irrespective of geographical location. Pressure support ventilation was the most common mode used during the spontaneous breathing trial. Conclusion: There was large heterogenicity of modes used between clinicians in general, in different disease states and in between different international geographical locations. Mechanical ventilation modes utilization varies widely and remains a personal preference with no consensus between clinicians globally. Keywords: Modes of mechanical ventilation, ARDS, COPD, SBT, survey