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Pathophysiology and classification of shock states

Pathophysiology of shock Circulatory shock represents a final common pathway of cardiovascular failure. Septic shock is the most common cause of shock followed by cardiogenic and hypovolemic shock. Mortality remains high, particularly for patients with septic and cardiogenic shock, where it approaches 40%. , From a physiologic perspective, circulatory shock is defined as a syndrome in which blood flow is inadequate to meet cellular metabolic requirements.…

Hypertensive crisis: Emergency and urgency

Hypertension is a common problem, and population data suggest its incidence is increasing globally. One billion individuals worldwide now have hypertension. Nearly one in three US adults has hypertension. Compared with two-thirds in the past decade, currently half of these individuals do not have their blood pressure under control. One-third of those in whom it is not controlled are unaware of their diagnosis. , The exact…

Pulmonary hypertension and right ventricular failure

Pulmonary hypertension (PH) is defined by an elevated mean pulmonary artery pressure (mPAP) of >20 mm Hg and may be precapillary or postcapillary in etiology. Precapillary PH is further characterized by an elevated pulmonary vascular resistance (PVR) of ≥3 Wood units and a pulmonary arterial wedge pressure of ≤15 mm Hg. Management of postcapillary PH, which is caused by left-sided heart dysfunction, typically involves treating the…

Emergency heart valve disorders

Key concepts in the management of a critically ill patient with valvular heart disease are the use of echocardiography to provide an accurate diagnosis of disease severity and the appropriate use of invasive hemodynamic monitoring to optimize loading conditions. Physical examination is not reliable for diagnosing the presence or severity of valvular heart disease, particularly in patients with acute hemodynamic compensation. Handheld echocardiography may provide clues…

Pericardial diseases

Etiology and classification of pericardial disease The spectrum of pericardial diseases consists of congenital defects, pericarditis (dry, effusive, effusive-constrictive, or constrictive), neoplasms, and cysts. The etiologic classification comprises infectious pericarditis, pericarditis in systemic autoimmune diseases, type 2 (auto) immune process, postmyocardial infarction syndrome, and autoreactive (chronic) pericarditis. , Pericardial syndromes Congenital defects of the pericardium Congenital defects of the pericardium are found in 1 in 10,000…

Myocarditis and acute myopathies

Myocarditis Myocarditis is defined as inflammation of heart muscle. Many different etiologic agents have been implicated in this disease, but viral infections are the most common cause. Myocarditis can be associated with autoimmune and other systemic diseases and can be caused by adverse drug reactions. The clinical picture of myocarditis varies widely, from asymptomatic patients who fully recover without specific therapy and who suffer no long-term…

Conduction disturbances and cardiac pacemakers

Conduction disturbances Patients admitted to the intensive care unit (ICU) frequently have conduction disturbances because of their acute medical condition or underlying risk factors. The clinical manifestation varies broadly from asymptomatic to life-threatening events. Locating and understanding the conduction disturbances are vital to stratifying the patient’s risk and choosing the best medical or invasive therapy option. Normal cardiac conduction Depolarization of the myocardium begins spontaneously from…

Ventricular arrhythmias

Cardiac arrhythmias are common in critically ill patients and a frequent reason for hospital admission to areas with capability for continuous electrocardiographic monitoring and personnel trained in their recognition and management (e.g., intensive care units [ICUs] and telemetry units). Arrhythmias are supraventricular if they originate above the atrioventricular (AV) node, such as in atrial tissue or pulmonary veins. They may compromise stroke volume and create hemodynamic…

Supraventricular arrhythmias

Classification and epidemiology Supraventricular arrhythmias include rhythms arising from the sinus node and the adjacent atrial tissue (inappropriate sinus tachycardia, sinoatrial reentry tachycardia), both the right and left atria (atrial tachycardia, flutter, and fibrillation), the atrioventricular (AV) node (AV nodal reentry tachycardia, accelerated ectopic junctional rhythm), and the AV node with involvement of an accessory pathway or multiple pathways (AV reentry tachycardia) ( Fig. 71.1 ).…

Acute coronary syndromes: Therapy

Definition and clinical manifestations Acute coronary syndromes are a family of disorders that share similar pathogenic mechanisms and represent different points along a common continuum. They include ST elevation myocardial infarction (STEMI), non–ST segment elevation acute coronary syndrome (NSTE-ACS), and unstable angina (UA) pectoris. These syndromes account for nearly 2 million hospitalizations annually in the United States, and if patients who die before reaching the hospital…

Core principles of cardiovascular physiology and pathophysiology in critical illness

Introduction Metabolism in almost all living organisms is energized by the chemical reduction of oxygen (O 2 ). As such, provision of O 2 to tissues is of central importance for living beings, especially in the high O 2 consumption (VO 2 ) of mammals and birds. Accordingly, VO 2 has evolved to be tightly related to the organism’s energy demands. The Fick principle, a statement…

Nosocomial pneumonia

Definitions Nosocomial pneumonia is an infection of the pulmonary parenchyma caused by pathogens acquired in hospital settings. , Nosocomial pneumonia develops in patients admitted to the hospital for more than 48 hours, and the incubation period usually is no longer than 2 days. Among nosocomial pneumonias, ventilator-associated pneumonia (VAP), which is the main focus of this chapter, develops in intensive care unit (ICU) patients who have…

Community-acquired pneumonia

Introduction Pneumonia is an infection of the gas-exchanging units of the lung and has a wide spectrum of clinical severity, ranging from mild outpatient illness to severe respiratory failure and sepsis. Pneumonia and influenza together are the eighth leading cause of death in the United States and the number-one cause of death from infectious diseases. , Pneumococcal pneumonia–related hospitalization has been projected to increase 96% by…

Pneumothorax

Introduction The term pneumothorax was first coined by Itard in 1803. Pneumothorax is defined as the presence of air in the pleural space. Traditionally, pneumothorax has been categorized into primary, secondary, traumatic, and iatrogenic. Spontaneous pneumothorax is considered “primary” when there is no obvious underlying lung disease and “secondary” when there is a known underlying lung disease such as emphysema or cystic lung disease. As thoracic…

Pulmonary embolism

Introduction Venous thromboembolism (VTE) encompasses the continuum of disease that includes deep venous thrombosis (DVT; also sometimes referred to as deep vein thrombosis ) and pulmonary embolism (PE). The prototypical VTE event occurs when a blood clot forms in the deep veins of the legs, detaches, and then embolizes through the vasculature and heart to lodge in the pulmonary arteries, where it is referred to as…

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a major cause of death and disability worldwide, is one of the most common reasons for intensive care unit (ICU) admission. Several monographs review this complex disorder in some detail. , The intensivist’s view of COPD is predominantly physiologic, focusing on the impact of disrupted function on the individual’s normal homeostatic mechanisms. Although many important insights that have shaped our understanding…

Severe asthma exacerbation in adults

Magnitude of the problem and risk factors Each year in the United States, acute asthma accounts for approximately 1.8 million emergency department (ED) visits, 190,000 hospitalizations, and 3500 deaths. Although death rates have decreased slightly over the last 20 years, African Americans, women, and older patients continue to be at increased risk. For the subgroup of patients requiring hospital admission, in-hospital mortality is very low in…

Aspiration pneumonitis and pneumonia

Aspiration is defined as the misdirection of oropharyngeal or gastric contents into the larynx and lower respiratory tract. The consequent pulmonary syndromes that follow depend on the quantity and nature of the aspirated material, frequency and chronicity of aspiration, and nature of the host’s defense mechanisms. The most important acute syndromes include aspiration pneumonitis, characterized in its most severe form and in a predisposing setting as…

Drowning

Definition Drowning is the process of experiencing respiratory impairment from submersion or immersion in liquid. This process can be fatal, nonfatal with complications, or nonfatal without complications. This definition is increasingly used in the medical, professional, and research literature to allow consistent and correct data collection and comparison. Terms such as “near,” “dry,” “wet,” “secondary,” “active,” or “passive” drowning, and “delayed onset of respiratory distress” should…

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a common problem in the intensive care unit (ICU) that can complicate a wide spectrum of critical illnesses. First described by Ashbaugh and colleagues in 1967, the syndrome was initially termed adult respiratory distress syndrome to distinguish it from the respiratory distress syndrome of neonates. However, with the recognition that ARDS can affect children, the term acute has replaced adult…