Preface

Our editorial intention with this fifth edition of Principles of Critical Care is to craft a contemporary and definitive reference work at a time of truly unprecedented clinical demand and scientific rigor as the discipline of critical care medicine enters a second semicentennial since the emergence of intensive care units (ICUs) in Europe and North America.

When initially conceived in mid-2019, the mere notion that a global respiratory viral pandemic, COVID-19, would push critical care units into popular vernacular and social media feeds across the world, was inconceivable. As a specialty, critical care medicine has since its inception existed between the domains of other clinical disciplines, transcending the discrete niches of organ-based internal medicine, anesthesiology, emergency and trauma care, perioperative surgical care, neurosciences, pediatric and neonatal care. More recent advances have emerged through collaborative efforts including clinical and scholarly interactions with rehabilitation medicine, nutrition science, physical, social, and psychological therapists, and more recently the realms of molecular medicine and data science. While largely incremental, the first two decades of the 21st century have witnessed the emergence of critical care as a discrete and highly sophisticated medical discipline, characterized by interdisciplinary collaboration and organizational integration in large parts of the post-industrial world.

The emergence and very rapid global spread of the COVID-19 pandemic has been characterized by acute respiratory illness and progression in some patients to severe acute hypoxemic respiratory failure associated with mortality rates exceeding 35%. While catapulting ICUs and ICU teams to the forefront of public attention, the pandemic has also cast into sharp relief the remarkable capacities, sophistication, and limitations of critical care medicine to fulfill a mission of delivering patient-centered, multidisciplinary clinical care in comprehensive and resourceful learning health-care environments, while functioning under unprecedented levels of operational strain and human endurance. The emerging recognition of post-intensive care syndrome (PICS) and prolonged cognitive and functional impairments among survivors of critical illness are predicted to be a major societal and economic consequence of the pandemic and the short-term survival enhancements emerging from the critical care response to the COVID-19 pandemic.

The extraordinary response of critical care clinicians and related disciplines has been among the most remarkable, impactful, and transformative aspects of the initial response to the pandemic. Even as vaccine technology and development caught up and tamed the worst recurrent waves for the immunized, critical care services have been under immense strain. The rapid translation of preclinical mechanistic research regarding SARS-CoV-2 and the host response to infection through pragmatic clinical trials of novel therapies and dissemination through publication to clinical practice have all been precedent setting. The organizational and operational transformation of hospital systems to screen, triage, and manage the millions of gravely ill patients frequently, with limited access to sufficient personal protective equipment and advanced life-support equipment, was arguably among the most remarkable global endeavor in non-wartime human history.

It is in this unanticipated and rapidly evolving landscape of fundamental mechanistic science, clinical critical care, organizational and operational improvement, technical and engineering innovation, and burgeoning recognition of the discipline that the current edition was reconceived.

However, among the many gaps and opportunities emerging from the response to the global COVID-19 pandemic, four stand out in stark relief: (1) Disparities in critical care provision between societies in the post-industrial West and that for populations in the developing-world and global South; (2) prevalent disparities in disease burden, care provision, and outcomes for inner-city, underserved, and economically disadvantaged populations who have long been disadvantaged by systematic racism, gender-bias, and ethnic discrimination; (3) depletion of the intellectual and clinical skills of the critical care workforce through illness, exhaustion, burn-out, and retirement; and (4) enduring scientific and fiscal opportunities to translate fundamental mechanistic understandings of human biology and disease into effective, affordable, and widely implementable therapies. This last aspect is ever more cogent for high prevalence and highly morbid critical care conditions including sepsis, acute cardiovascular and neurological illnesses, and emerging infectious diseases.

In this fifth edition of Principles of Critical Care, we have endeavored to preserve the essence of the first four editions that has sustained a remarkable durability and support during the e-publication, on-line information revolution. The three editors are indebted to the mentorship, guidance, and collegiality of the founding editors, Lawrence D. H. Wood and Jesse B. Hall whose formulation of a pathophysiologically informed, rigorously evidence-based approach to humanistic critical care remains at the core of the text. It is from the inspiration and diligent mentorship of these outstanding clinician-scientists and scholars that we approach patient care, teaching, and investigation of critical care. Our shared approach is energized fundamentally by our clinical practice. In turn, our practice is informed, animated, and balanced by the information and environment arising around scholarship, adult learning, and hypothesis-based research. Clinical excellence remains founded in careful history taking, physical examination, and selective special investigations, in order to develop a prioritized differential diagnosis and formulate evidence-based cost-effective and patient-focused treatment plans. From our work we have evolved a deep appreciation for the central role of organizational effectiveness, systematization of accessible health-care information, and an abiding prioritization of the triadic relationship in critical care: the patient, the critical care team, and the patient's family/community.

The expansion of the critical care workforce and the contribution of scholarship by a wider diversity of researchers, clinicians, and educators demand of the current and future editions a substantially more inclusive and representative authorship to remain relevant and impactful. While much remains to be achieved, including a diversification of lead editorship, we have encouraged chapter multiauthorship to include emerging scholars of diverse backgrounds, experience, race, ethnicity, and gender/gender identity.

Like previous editions, the first section compiles core topics and concepts that provide the foundation for excellent pathophysiologically informed critical care as well as topics germane to the evaluation and management of most critically ill patients. To accomplish this and deliver a text that is both comprehensive and accessible, we have included “Key Points” at the beginning of each chapter and integrated numerous cross-references throughout the work. The subsequent chapters follow an organ system orientation for in-depth, contemporaneous, and mechanistically informed description of the unique presentation, differential diagnosis, and management of specific critical illnesses. Across all chapters we have highlighted the emerging understanding of clinical subphenotypes, treatable traits, and precision approaches to disease diagnosis and treatments. Finally, we include topics of a cross-disciplinary nature that inform the delivery of highly reliable, high-quality critical care.

In this fifth edition, we have added new chapters on oxygen delivery systems, pandemics, COVID-19, and hemophagocytic lymphohistiocytosis (HLH) among others. The changing nature of modern critical care spawned new or completely revised chapters regarding Preventive Bundles, Informatics, Statistics, Rapid Response Teams, Physical Therapy, and more. In addition, we recognize that critical illness stresses entire systems, not just individual patients, so we have created new contributions on caregiver and family issues and on the implications of disordered sleep for the critically ill. We have further enhanced cross-disciplinary chapters addressing the structures and systems of critical care including staffing, safety, and informatics. And in response to the emergence of the COVID-19 pandemic we include new material regarding critical care pandemic preparedness and response as well as separate chapters regarding the pathogenesis, clinical presentations, and management of COVID-19-related critical illnesses.

Gregory A. Schmidt, MD, one of the original editors of the first three editions of Principles of Critical Care, has over the last two-and-half decades provided enduring mentorship, guidance, and professional direction for John P. (JP) Kress, MD, and Ivor S. Douglas, MD, who are honored to be joining as co-editors for the fifth edition. While Dr. Kress has remained at the “mothership” (the University of Chicago) as a professor of pulmonary and critical care medicine and leading the medical ICU, Drs. Schmidt and Douglas joined the faculties at University of Iowa and University of Colorado, respectively, where they have endeavored to disseminate and expand on the visionary, pathophysiologically informed approach to critical care research and care delivery of Drs. Wood and Hall.

We, the editors, have endeavored to compile and integrate with diligence and responsibility the collective insights, wisdom, and experience of our authors to whom we are both humbly indebted and to whose families and colleagues we are extremely appreciative and grateful. Many chapter submissions were prepared during a time of unprecedented stress and time-constraint for the authors. Their “day-jobs” involve the care of critically ill patients, many suffering from COVID-19, in addition to designing and conducting innovative fundamental mechanistic and clinical research studies while providing administrative direction for critical care programs and ICUs.

The challenges and delights of editorial coaxing, review, and production are inherently laborious, even during nonpandemic times. The editors are abidingly grateful and appreciative of the skilled oversight, editorial support, and patience exhibited by McGraw Hill's senior project development editor Christie Naglieri and her team for their meticulous support and guidance in the preparation and production of this text.

The nuanced reality, clinical complexity, and humbling limitations apparent in the care of the critically ill provide an enduring motivation for our search to better characterize and understand the pathophysiology and mechanisms of critical illness while contributing to new, effective diagnoses, therapies, and care systems. It is our hope that this textbook reflects the interweaving and mutually supporting threads of critical care practice, teaching, and research. Whether you chose to access this volume in its printed format or electronically we appreciate your engagement with the text and eagerly anticipate your feedback and guidance in continuing to improve the content and structure of Principles of Critical Care.