The Pathophysiology of 'Happy' Hypoxemia in COVID-19
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Job Hazard Analysis
Identifying and Evaluating Hazards in Research Laboratories Guidelines developed by the Hazards Identification and Evaluation Task Force of the American Chemical Society’s Committee on Chemical Safety Copyright 2013 American Chemical Society Table of Contents FOREWORD ................................................................................................................................................... 3 ACKNOWLEDGEMENTS ................................................................................................................................. 5 Task Force Members ..................................................................................................................................... 6 1. SCOPE AND APPLICATION ..................................................................................................................... 7 2. DEFINITIONS .......................................................................................................................................... 7 3. HAZARDS IDENTIFICATION AND EVALUATION ................................................................................... 10 4. ESTABLISHING ROLES AND RESPONSIBILITIES .................................................................................... 14 5. CHOOSING AND USING A TECHNIQUE FROM THIS GUIDE ................................................................. 17 6. CHANGE CONTROL .............................................................................................................................. 19 7. ASSESSING -
Airway Pressures and Volutrauma
Airway Pressures and Volutrauma Airway Pressures and Volutrauma: Is Measuring Tracheal Pressure Worth the Hassle? Monitoring airway pressures during mechanical ventilation is a standard of care.1 Sequential recording of airway pressures not only provides information regarding changes in pulmonary impedance but also allows safety parameters to be set. Safety parameters include high- and low-pressure alarms during positive pressure breaths and disconnect alarms. These standards are, of course, based on our experience with volume control ventilation in adults. During pressure control ventilation, monitoring airway pressures remains important, but volume monitoring and alarms are also required. Airway pressures and work of breathing are also important components of derived variables, including airway resistance, static compliance, dynamic compliance, and intrinsic positive end-expiratory pressure (auto-PEEP), measured at the bedside.2 The requisite pressures for these variables include peak inspiratory pressure, inspiratory plateau pressure, expiratory plateau pressure, and change in airway pressure within a breath. Plateau pressures should be measured at periods of zero flow during both volume control and pressure control ventilation. Change in airway pressure should be measured relative to change in volume delivery to the lung (pressure-volume loop) to elucidate work of breathing. See the related study on Page 1179. Evidence that mechanical ventilation can cause and exacerbate acute lung injury has been steadily mounting.3-5 While most of this evidence has originated from laboratory animal studies, recent clinical reports appear to support this concept.6,7 Traditionally, ventilator-induced lung injury brings to mind the clinical picture of tension pneumothorax. Barotrauma (from the root word baro, which means pressure) is typically associated with excessive airway pressures. -
Ventilation Patterns Influence Airway Secretion Movement Marcia S Volpe, Alexander B Adams MPH RRT FAARC, Marcelo B P Amato MD, and John J Marini MD
Original Contributions Ventilation Patterns Influence Airway Secretion Movement Marcia S Volpe, Alexander B Adams MPH RRT FAARC, Marcelo B P Amato MD, and John J Marini MD BACKGROUND: Retention of airway secretions is a common and serious problem in ventilated patients. Treating or avoiding secretion retention with mucus thinning, patient-positioning, airway suctioning, or chest or airway vibration or percussion may provide short-term benefit. METHODS: In a series of laboratory experiments with a test-lung system we examined the role of ventilator settings and lung-impedance on secretion retention and expulsion. Known quantities of a synthetic dye-stained mucus simulant with clinically relevant properties were injected into a transparent tube the diameter of an adult trachea and exposed to various mechanical-ventilation conditions. Mucus- simulant movement was measured with a photodensitometric technique and examined with image- analysis software. We tested 2 mucus-simulant viscosities and various peak flows, inspiratory/ expiratory flow ratios, intrinsic positive end-expiratory pressures, ventilation waveforms, and impedance values. RESULTS: Ventilator settings that produced flow bias had a major effect on mucus movement. Expiratory flow bias associated with intrinsic positive end-expiratory pressure generated by elevated minute ventilation moved mucus toward the airway opening, whereas in- trinsic positive end-expiratory pressure generated by increased airway resistance moved the mucus toward the lungs. Inter-lung transfer of mucus simulant occurred rapidly across the “carinal divider” between interconnected test lungs set to radically different compliances; the mucus moved out of the low-compliance lung and into the high-compliance lung. CONCLUSIONS: The move- ment of mucus simulant was influenced by the ventilation pattern and lung impedance. -
COVID-19 Pneumonia: Different Respiratory Treatment for Different Phenotypes? L
Intensive Care Medicine EDITORIAL Un-edited accepted proof COVID-19 pneumonia: different respiratory treatment for different phenotypes? L. Gattinoni1, D. Chiumello2, P. Caironi3, M. Busana1, F. Romitti1, L. Brazzi4, L. Camporota5 Affiliations: 1Department of Anesthesiology and Intensive Care, Medical University of GöttinGen 4Department of Anesthesia, Intensive Care and Emergency - 'Città della Salute e della Scienza’ Hospital - Turin 5Department of Adult Critical Care, Guy’s and St Thomas’ NHS Foundation Trust, Health Centre for Human and Applied Physiological Sciences - London Corresponding author: Luciano Gattinoni Department of Anesthesiology and Intensive Care, Medical University of Göttingen, Robert-Koch Straße 40, 37075, Göttingen, Germany Conflict of interests: The authors have no conflict of interest to disclose NOTE: This article is the pre-proof author’s accepted version. The final edited version will appear soon on the website of the journal Intensive Care Medicine with the following DOI number: DOI 10.1007/s00134-020-06033-2 1 Gattinoni L. et al. COVID-19 pneumonia: different respiratory treatment for different phenotypes? (2020) Intensive Care Medicine; DOI: 10.1007/s00134-020-06033-2 Intensive Care Medicine EDITORIAL Un-edited accepted proof The Surviving Sepsis CampaiGn panel (ahead of print, DOI: 10.1007/s00134-020-06022-5) recently recommended that “mechanically ventilated patients with COVID-19 should be managed similarly to other patients with acute respiratory failure in the ICU.” Yet, COVID-19 pneumonia [1], despite falling in most of the circumstances under the Berlin definition of ARDS [2], is a specific disease, whose distinctive features are severe hypoxemia often associated with near normal respiratory system compliance (more than 50% of the 150 patients measured by the authors and further confirmed by several colleagues in Northern Italy). -
Approach to Cyanosis in a Neonate.Pdf
PedsCases Podcast Scripts This podcast can be accessed at www.pedscases.com, Apple Podcasting, Spotify, or your favourite podcasting app. Approach to Cyanosis in a Neonate Developed by Michelle Fric and Dr. Georgeta Apostol for PedsCases.com. June 29, 2020 Introduction Hello, and welcome to this pedscases podcast on an approach to cyanosis in a neonate. My name is Michelle Fric and I am a fourth-year medical student at the University of Alberta. This podcast was made in collaboration with Dr. Georgeta Apostol, a general pediatrician at the Royal Alexandra Hospital Pediatrics Clinic in Edmonton, Alberta. Cyanosis refers to a bluish discoloration of the skin or mucous membranes and is a common finding in newborns. It is a clinical manifestation of the desaturation of arterial or capillary blood and may indicate serious hemodynamic instability. It is important to have an approach to cyanosis, as it can be your only sign of a life-threatening illness. The goal of this podcast is to develop this approach to a cyanotic newborn with a focus on these can’t miss diagnoses. After listening to this podcast, the learner should be able to: 1. Define cyanosis 2. Assess and recognize a cyanotic infant 3. Develop a differential diagnosis 4. Identify immediate investigations and management for a cyanotic infant Background Cyanosis can be further broken down into peripheral and central cyanosis. It is important to distinguish these as it can help you to formulate a differential diagnosis and identify cases that are life-threatening. Peripheral cyanosis affects the distal extremities resulting in blue color of the hands and feet, while the rest of the body remains pinkish and well perfused. -
Hyperventilation Syndrome
Hyperventilation Syndrome INTRODUCTION ● hyperventilation in the presence of the following should immediately confirm an alternative Hyperventilation syndrome is defined as “a rate of diagnosis: ventilation exceeding metabolic needs and higher than that required to maintain a normal level of plasma CO2”. – cyanosis Physiological hyperventilation can occur in a number of – reduced level of consciousness situations, including life-threatening conditions such as: – reduction in SpO2. ● pulmonary embolism ● diabetic ketoacidosis MANAGEMENT 1,2 ● asthma If ABCD need correction then treat as per medical ● hypovolaemia. guidelines as it is unlikely to be due to hyperventilation syndrome but is more likely to be physiological As a rule, hyperventilation due to emotional stress is hyperventilation secondary to an underlying rare in children, and physical causes are much more pathological process. likely to be responsible for hyperventilation. Maintain a calm approach at all times. Specific presenting features can include: Reassure the patient and try to remove the source of ● acute anxiety the patient’s anxiety, this is particularly important in ● tetany due to calcium imbalance children. ● numbness and tingling of the mouth and lips Coach the patient’s respirations whilst maintaining a calm environment. ● carpopedal spasm ● aching of the muscles of the chest ADDITIONAL INFORMATION ● feeling of light headedness or dizziness. The cause of hyperventilation cannot always be determined with sufficient accuracy (especially in the HISTORY early stages) in the pre hospital environment. Refer to dyspnoea guide Always presume hyperventilation is secondary to hypoxia or other underlying respiratory disorder until proven otherwise. 1,2 ASSESSMENT The resulting hypocapnia will result in respiratory Assess ABCD’s: alkalosis bringing about a decreased level of serum ionised calcium. -
Cerebrospinal Fluid in Critical Illness
Cerebrospinal Fluid in Critical Illness B. VENKATESH, P. SCOTT, M. ZIEGENFUSS Intensive Care Facility, Division of Anaesthesiology and Intensive Care, Royal Brisbane Hospital, Brisbane, QUEENSLAND ABSTRACT Objective: To detail the physiology, pathophysiology and recent advances in diagnostic analysis of cerebrospinal fluid (CSF) in critical illness, and briefly review the pharmacokinetics and pharmaco- dynamics of drugs in the CSF when administered by the intravenous and intrathecal route. Data Sources: A review of articles published in peer reviewed journals from 1966 to 1999 and identified through a MEDLINE search on the cerebrospinal fluid. Summary of review: The examination of the CSF has become an integral part of the assessment of the critically ill neurological or neurosurgical patient. Its greatest value lies in the evaluation of meningitis. Recent publications describe the availability of new laboratory tests on the CSF in addition to the conventional cell count, protein sugar and microbiology studies. Whilst these additional tests have improved our understanding of the pathophysiology of the critically ill neurological/neurosurgical patient, they have a limited role in providing diagnostic or prognostic information. The literature pertaining to the use of these tests is reviewed together with a description of the alterations in CSF in critical illness. The pharmacokinetics and pharmacodynamics of drugs in the CSF, when administered by the intravenous and the intrathecal route, are also reviewed. Conclusions: The diagnostic utility of CSF investigation in critical illness is currently limited to the diagnosis of an infectious process. Studies that have demonstrated some usefulness of CSF analysis in predicting outcome in critical illness have not been able to show their superiority to conventional clinical examination. -
Asphyxia Neonatorum
CLINICAL REVIEW Asphyxia Neonatorum Raul C. Banagale, MD, and Steven M. Donn, MD Ann Arbor, Michigan Various biochemical and structural changes affecting the newborn’s well being develop as a result of perinatal asphyxia. Central nervous system ab normalities are frequent complications with high mortality and morbidity. Cardiac compromise may lead to dysrhythmias and cardiogenic shock. Coagulopathy in the form of disseminated intravascular coagulation or mas sive pulmonary hemorrhage are potentially lethal complications. Necrotizing enterocolitis, acute renal failure, and endocrine problems affecting fluid elec trolyte balance are likely to occur. Even the adrenal glands and pancreas are vulnerable to perinatal oxygen deprivation. The best form of management appears to be anticipation, early identification, and prevention of potential obstetrical-neonatal problems. Every effort should be made to carry out ef fective resuscitation measures on the depressed infant at the time of delivery. erinatal asphyxia produces a wide diversity of in molecules brought into the alveoli inadequately com Pjury in the newborn. Severe birth asphyxia, evi pensate for the uptake by the blood, causing decreases denced by Apgar scores of three or less at one minute, in alveolar oxygen pressure (P02), arterial P02 (Pa02) develops not only in the preterm but also in the term and arterial oxygen saturation. Correspondingly, arte and post-term infant. The knowledge encompassing rial carbon dioxide pressure (PaC02) rises because the the causes, detection, diagnosis, and management of insufficient ventilation cannot expel the volume of the clinical entities resulting from perinatal oxygen carbon dioxide that is added to the alveoli by the pul deprivation has been further enriched by investigators monary capillary blood. -
Prolonged Post-Hyperventilation Apnea in Two Young Adults With
Munemoto et al. BioPsychoSocial Medicine 2013, 7:9 http://www.bpsmedicine.com/content/7/1/9 CASE REPORT Open Access Prolonged post-hyperventilation apnea in two young adults with hyperventilation syndrome Takao Munemoto1,4*, Akinori Masuda2, Nobuatsu Nagai3, Muneki Tanaka4 and Soejima Yuji5 Abstract Background: The prognosis of hyperventilation syndrome (HVS) is generally good. However, it is important to proceed with care when treating HVS because cases of death following hyperventilation have been reported. This paper was done to demonstrate the clinical risk of post-hyperventilation apnea (PHA) in patients with HVS. Case presentation: We treated two patients with HVS who suffered from PHA. The first, a 21-year-old woman, had a maximum duration of PHA of about 3.5 minutes and an oxygen saturation (SpO2) level of 60%. The second patient, a 22-year-old woman, had a maximum duration of PHA of about 3 minutes and an SpO2 level of 66%. Both patients had loss of consciousness and cyanosis. Because there is no widely accepted regimen for treating patients with prolonged PHA related to HVS, we administered artificial ventilation to both patients using a bag mask and both recovered without any after effects. Conclusion: These cases show that some patients with HVS develop prolonged PHA or severe hypoxia, which has been shown to lead to death in some cases. Proper treatment must be given to patients with HVS who develop PHA to protect against this possibility. If prolonged PHA or severe hypoxemia arises, respiratory assistance using a bag mask must be done immediately. Keywords: Post-hyperventilation apnea, PHA, Hyperventilation syndrome, HVS, Hypocapnia, Hypoxemia Background incidence of death, severe hypoxia, or myocardial infarc- Hyperventilation syndrome (HVS) is characterized by tion in association with the paper-bag method [2]. -
CARBON MONOXIDE: the SILENT KILLER Information You Should
CARBON MONOXIDE: THE SILENT KILLER Information You Should Know Carbon monoxide is a silent killer that can lurk within fossil fuel burning household appliances. Many types of equipment and appliances burn different types of fuel to provide heat, cook, generate electricity, power vehicles and various tools, such as chain saws, weed eaters and leaf blowers. When these units operate properly, they use fresh air for combustion and vent or exhaust carbon dioxide. When fresh air is restricted, through improper ventilation, the units create carbon monoxide, which can saturate the air inside the structure. Carbon Monoxide can be lethal when accidentally inhaled in concentrated doses. Such a situation is referred to as carbon monoxide poisoning. This is a serious condition that is a medical emergency that should be taken care of right away. What Is It? Carbon monoxide, often abbreviated as CO, is a gas produced by burning fossil fuel. What makes it such a silent killer is that it is odorless and colorless. It is extremely difficult to detect until the body has inhaled a detrimental amount of the gas, and if inhaled in high concentrations, it can be fatal. Carbon monoxide causes tissue damage by blocking the body’s ability to absorb enough oxygen. In fact, poisoning from this gas is one of the leading causes of unintentional death from poison. Common Sources of CO Kerosene or fuel-based heaters Fireplaces Gasoline powered equipment and generators Charcoal grills Automobile exhaust Portable generators Tobacco smoke Chimneys, furnaces, and boilers Gas water heaters Wood stoves and gas stoves Properly installed and maintained appliances are safe and efficient. -
Clinical Management of Severe Acute Respiratory Infections When Novel Coronavirus Is Suspected: What to Do and What Not to Do
INTERIM GUIDANCE DOCUMENT Clinical management of severe acute respiratory infections when novel coronavirus is suspected: What to do and what not to do Introduction 2 Section 1. Early recognition and management 3 Section 2. Management of severe respiratory distress, hypoxemia and ARDS 6 Section 3. Management of septic shock 8 Section 4. Prevention of complications 9 References 10 Acknowledgements 12 Introduction The emergence of novel coronavirus in 2012 (see http://www.who.int/csr/disease/coronavirus_infections/en/index. html for the latest updates) has presented challenges for clinical management. Pneumonia has been the most common clinical presentation; five patients developed Acute Respira- tory Distress Syndrome (ARDS). Renal failure, pericarditis and disseminated intravascular coagulation (DIC) have also occurred. Our knowledge of the clinical features of coronavirus infection is limited and no virus-specific preven- tion or treatment (e.g. vaccine or antiviral drugs) is available. Thus, this interim guidance document aims to help clinicians with supportive management of patients who have acute respiratory failure and septic shock as a consequence of severe infection. Because other complications have been seen (renal failure, pericarditis, DIC, as above) clinicians should monitor for the development of these and other complications of severe infection and treat them according to local management guidelines. As all confirmed cases reported to date have occurred in adults, this document focuses on the care of adolescents and adults. Paediatric considerations will be added later. This document will be updated as more information becomes available and after the revised Surviving Sepsis Campaign Guidelines are published later this year (1). This document is for clinicians taking care of critically ill patients with severe acute respiratory infec- tion (SARI). -
The Basics of Ventilator Management Overview How We Breath
3/23/2019 The Basics of Ventilator Management What are we really trying to do here Peter Lutz, MD Pulmonary and Critical Care Medicine Pulmonary Associates, Mobile, Al Overview • Approach to the physiology of the lung and physiological goals of mechanical Ventilation • Different Modes of Mechanical Ventilation and when they are indicated • Ventilator complications • Ventilator Weaning • Some basic trouble shooting How we breath http://people.eku.edu/ritchisong/301notes6.htm 1 3/23/2019 How a Mechanical Ventilator works • The First Ventilator- the Iron Lung – Worked by creating negative atmospheric pressure around the lung, simulating the negative pressure of inspiration How a Mechanical Ventilator works • The Modern Ventilator – The invention of the demand oxygen valve for WWII pilots if the basis for the modern ventilator https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRI5v-veZULMbt92bfDmUUW32SrC6ywX1vSzY1xr40aHMdsCVyg6g How a Mechanical Ventilator works • The Modern Ventilator – How it works Inspiratory Limb Flow Sensor Ventilator Pressure Sensor Expiratory Limb 2 3/23/2019 So what are the goals of Mechanical Ventilation • What are we trying to control – Oxygenation • Amount of oxygen we are getting into the blood – Ventilation • The movement of air into and out of the lungs, mainly effects the pH and level of CO 2 in the blood stream Lab Oxygenation Ventilation Pulse Ox Saturation >88-90% Arterial Blood Gas(ABG) Po 2(75-100 mmHg) pCO 2(40mmHg) pH(~7.4) Oxygenation How do we effect Oxygenation • Fraction of Inspired Oxygen (FIO 2) – Percentage of the gas mixture given to the patient that is Oxygen • Room air is 21% • On the vent ranges from 30-100% • So if the patient’s blood oxygen levels are low, we can just increase the amount of oxygen we give them 3 3/23/2019 How do we effect Oxygenation • Positive End Expiratory Pressure (PEEP) – positive pressure that will remains in the airways at the end of the respiratory cycle (end of exhalation) that is greater than the atmospheric pressure in mechanically ventilated patients.