Preface

Adequate oxygenation and carbon dioxide removal are integral parts of respiratory system homeostasis. In respiratory failure, one or both of these vital functions are compromised. Respiratory failure can be due to pump failure manifested by hypercapnia and lung failure manifested by gas exchange failure and hypoxemia. Four pathophysiological mechanisms can lead to respiratory failure: ventilationperfusion mismatch, shunt, diffusion impairment, and alveolar hypoventilation [1, 2]. Incidence of respiratory failure is 137.1/100,000, with mortality as high as 29%–42%. In the United States in 2017, there were approximately 1,146,195 patients discharged from the hospital with the diagnosis of respiratory failure, with an average length and hospital charge of 10.5 days and a cost per admission of \$158,493 [3, 4]. While the incidence of cardiovascular disease is decreasing, the incidence and prevalence of respiratory illness, including obstructive lung disease, is on the rise. Globally, 545 million people live with respiratory illness, representing 7.4% of the world's population. Chronic obstructive pulmonary disease is the third leading cause of death globally, with 3.2 million deaths in 2019. In addition, there were 495,000 deaths due to asthma [5]. Respiratory illness accounts for 20% of all mortality. In addition, the COVID-19 pandemic created global havoc with the SARS-CoV2 virus causing respiratory failure and associated high mortality. COVID patients who required mechanical ventilation had an increased risk of death [6, 7].

This book provides a comprehensive overview of respiratory insufficiency. In the first section, Chapter 1 discusses the pathophysiology of respiratory failure. It addresses the anatomy and physiology of the respiratory system and examines lung volume, capacities, and changes during obstructive and restrictive lung disease. In addition, it discusses the pathophysiology of hypoxemia and hypercapnia and the physiological response to the pathologies.

Section 2 discusses respiratory failure in obstructive lung disease. Chapter 2 discusses acute respiratory failure exacerbating bronchial asthma. The chapter reviews the pathogenesis of asthma, early and late response to antigens, airway remodeling phenomenon, and other factors such as microbiome and microbiota. It also discusses dynamic hyperinflation and its predisposing factors. Chapter 3 on respiratory support in obstructive syndrome discusses the biomechanics and gas exchange in acute respiratory failure, respiratory support, and its algorithm. It also discusses the challenges for patients with mechanical ventilation.

Section 3 addresses issues in patients with respiratory failure due to COVID-19. As mentioned, patients with respiratory failure due to COVID-19 have high mortality. Chapter 4 discusses the clinical manifestation and management of respiratory failure in COVID patients as compared to that in non-COVID-19 patients.

Section 4 addresses respiratory failure in specialized conditions, including in patients with liver disease, and the management of mechanical ventilation in burn patients,

which carries a high mortality. Chapter 5 discusses porto-pulmonary hypertension and hepatopulmonary syndrome. It discusses the clinical features, diagnosis, and management of these conditions as well as the role of liver transplant in patients with hepatopulmonary syndrome. Chapter 6 discusses airway management in burn patients, including those with carbon monoxide and cyanide toxicity and inhalation injury. It also reviews the diagnosis and mechanical ventilation management among burn patients.

The book concludes with Section 5 on the role of veno-venous extracorporeal membrane oxygenation (VV-ECMO) in respiratory failure. Chapter 7 discusses the physiology of VV-ECMO as well as its management and complications. It also discusses the role of VV-ECMO in patients with acute respiratory distress syndrome (ARDS) due to COVID-19.

This book provides an understanding of the basic physiology and management of patients with respiratory insufficiency. It discusses specialized populations with respiratory failure and the role of VV-ECMO. We hope that readers will find this book useful and informative.

### **Salim Surani, MD, MPH, MSHM, FACP, FCCP, FAASM, FCCM**

Clinical Professor, Texas A&M University, College Station, Texas, USA

Visiting Professor, Aga Khan University, Nairobi, Kenya

#### **Syed Anjum Khan, MD**

**V**

[1] Roussos C, Koutsoukou A. Respiratory failure. The European respiratory journal

[2] Gandhi KD, Sharma M, Taweesedt PT, Surani S. Role of proning and positive end-expiratory pressure in COVID-19. World J Crit Care Med. 2021;**10**(5):183-93

[3] Kempker JA, Abril MK, Chen Y, Kramer MR, Waller LA, Martin GS. The Epidemiology of Respiratory Failure in the United States 2002-2017: A Serial Cross-Sectional Study. Crit Care Explor.

[4] Viegi G, Maio S, Fasola S, Baldacci S. Global Burden of Chronic Respiratory Diseases. J Aerosol Med Pulm Drug Deliv.

Obstructive Lung Disease: World Health Organization; 2023 [Available from: https://www.who.int/news-room/ fact-sheets/detail/chronic-obstructive-

[5] Organization WH. Chronic

pulmonary-disease-(copd)

diseases: Panel data evidence from Chile. Infect Ecol Epidemiol.

2022;**12**(1):2023939

2021;**11**(5):576-84

[6] Barria-Sandoval C, Ferreira G, Mendez A, Toffoletto MC. Impact of COVID-19 on deaths from respiratory

[7] Asghar MS, Yasmin F, Haris A, Nadeem A, Taweesedt PT, Surani S. Comparison of first and second waves of COVID-19 through severity markers in ICU patients of a developing country. J Community Hosp Intern Med Perspect.

2020;**2**(6):e0128

2020;**33**(4):171-7

Supplement. 2003;**47**:3s-14s

**References**

Regional Chair of Critical Care Medicine, Southwest Minnesota Mayo Clinic Health System, Minnesota, USA

**Reena Shah, MD, MRCP (lon), DTM&H, MScID (Lon), FRCP(Edin), FRCP(Lon)** Associate Professor and Chief of Medicine, Aga Khan University, Nairobi, Kenya

#### **References**

[1] Roussos C, Koutsoukou A. Respiratory failure. The European respiratory journal Supplement. 2003;**47**:3s-14s

[2] Gandhi KD, Sharma M, Taweesedt PT, Surani S. Role of proning and positive end-expiratory pressure in COVID-19. World J Crit Care Med. 2021;**10**(5):183-93

[3] Kempker JA, Abril MK, Chen Y, Kramer MR, Waller LA, Martin GS. The Epidemiology of Respiratory Failure in the United States 2002-2017: A Serial Cross-Sectional Study. Crit Care Explor. 2020;**2**(6):e0128

[4] Viegi G, Maio S, Fasola S, Baldacci S. Global Burden of Chronic Respiratory Diseases. J Aerosol Med Pulm Drug Deliv. 2020;**33**(4):171-7

[5] Organization WH. Chronic Obstructive Lung Disease: World Health Organization; 2023 [Available from: https://www.who.int/news-room/ fact-sheets/detail/chronic-obstructivepulmonary-disease-(copd)

[6] Barria-Sandoval C, Ferreira G, Mendez A, Toffoletto MC. Impact of COVID-19 on deaths from respiratory diseases: Panel data evidence from Chile. Infect Ecol Epidemiol. 2022;**12**(1):2023939

[7] Asghar MS, Yasmin F, Haris A, Nadeem A, Taweesedt PT, Surani S. Comparison of first and second waves of COVID-19 through severity markers in ICU patients of a developing country. J Community Hosp Intern Med Perspect. 2021;**11**(5):576-84

Section 1

Pathophysiology of

Respiratory Failure

**1**

Section 1
