Abstract
Background
Coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus, was first identified in late 2019 and went on to profoundly disrupt health care systems worldwide. The pandemic led to unprecedented increases in healthcare delivery costs, widespread disruption in medical supply chains, workforce instability, and a loss of typical inpatient caregiver support. These challenges affected all levels of care, from primary health services to highly specialized intensive care units (ICUs). Before vaccines were available, ICUs were overwhelmed by critically ill patients requiring mechanical ventilation, saturating capacity and straining staff.
Objectives
This article seeks to examine the effect that COVID-19 had on ICUs globally, acknowledging its impact with an aim to identify solutions that can be used to help mitigate the overburdening of this limited resource in future pandemics.
Methods
A narrative review approach was used, drawing on published literature, observational data, and institutional responses from 2020 to 2025, to analyze structural, operational, and clinical adjustments in ICU design and function.
Results
Key adaptations included physical redesigns, rapid infection-control upgrades, the use of negative pressure rooms, expansion of tele-ICU systems, and virtual family engagement strategies. These interventions were implemented to address ICU crowding, equipment shortages, and staff burnout, and helped to maintain continuity of care during surge conditions.
Conclusions
The COVID-19 pandemic demonstrated the need for ICUs to be more agile, scalable, and future-facing. Lessons learned highlight the importance of preparedness strategies that strengthen ICU resilience and support critical care delivery in future public health emergencies.
Keywords
Introduction
A defining moment for intensive care units (ICUs) came with the onset of the polio epidemic. From general nursing care for all patients to the development of separate units manned by more nurses and an expansion of ICUs tailored for different specialties- cardiac, neurocritical, surgical and medical. ICU care has since become highly skilled and specialized, contributing to improved global morbidity and mortality outcomes.
The emergence of Coronavirus Disease 2019 (COVID-19) brought further transitions and transformations in both the physical design and care models of the ICU. We examine the evolution of ICU care during the pandemic, including changes in physical layout, visiting policies, impact of medication shortages, staffing dynamics, their overall impact on patient care, and the innovations that emerged in response to these challenges, summarized in Table 1.
Key ICU Adaptations in Response to COVID-19 Challenges.
ICU History
ICUs were developed informally and then more formally as it became clear that certain patients required closer monitoring and more frequent nursing care. The separation of critically injured patients from those with non-critical injuries was first implemented during the Crimean War in 1854, through the efforts of English nurse Florence Nightingale. 1 She introduced the practice of positioning the most critically injured soldiers directly in front of the nursing station, allowing for increased monitoring and specialized nursing care. In 1923, neurosurgeon Walter Dandy established a unit at Johns Hopkins Hospital in Baltimore for critically ill postoperative neurosurgical patients to be cared for by specially trained nurses. During World War II in the 1940s, specialized shock units and postoperative observation areas were widely used to efficiently care for severely wounded soldiers, leading to the expanded use of postoperative recovery units after the war.
The emergence of the polio epidemic in many countries in the 1950s led to the widespread adoption of ICU care across the United States and Europe.2,3 The first ICU was established in Copenhagen in 1953 by anesthetist Bjørn Ibsen. 3 As respiratory failure became a common complication in polio patients, the epidemic brought with it innovation in the form of positive pressure ventilation, which had not been widely available before. 3 Through Ibsen's efforts, the introduction of special units utilizing positive pressure machines and medical students being paid to work shifts alongside physicians, led to a reduction in polio-related mortality from 80% to 40%. Following the introduction of the positive pressure machines, a special care unit with each patient having their own nurse was born, resulting in the modern-day ICU.
Since the mid-1950s, intensive care has had more innovations in design, modes of staffing, physical outlay, knowledge, technology and procedural techniques that have propelled its rapid expansion. Ventilators and ICU monitoring equipment have become unrecognizably advanced, and many more team members are required for increased efficiency and improved patient outcomes. Initially, ICUs were usually staffed by internists or anesthesiologists, and patients within the same unit were often seen by their own admitting physicians. 4 In modern ICUs, patients are cared for by a multifaceted team which includes critical care physicians and nurses, advanced practice providers (APPs), respiratory therapists, dietitians, speech, physical, and occupational therapists, palliative care providers, and pharmacists, who play distinct and essential roles in patient management. Respiratory therapists oversee ventilator management and pulmonary care, pharmacists guide medication selection, dosing, and safety, and APPs extend the reach of intensivists in both clinical decision-making and direct patient care. Many hospitals now have rapid response teams to assess and treat deteriorating patients in the wards before they require ICU admission. This integrated team approach has been shown to improve patient outcomes.
The Impact of COVID-19 on Traditional ICU Design
With polio heralding the birth of the modern-day ICU, COVID-19 can be said to have contributed to the evolution of ICUs with facilities extending the scope of the ICU outside of its traditional boundaries.
The COVID-19 pandemic, which began in 2020, resulted in numerous changes to ICU structure and workflow across the world. The number of critically ill patients admitted to ICUs surged to unprecedented levels, placing enormous strain on ICU resources and staff. 5 The high volume of patients led to a shortage of bed space, personal protective equipment (PPE), ventilators, and an overwhelmed intensive care staff. ICUs across the world were forced to expand bed capacity, increase their inventory of PPE and ventilators, convert other areas of the hospital to ICU space, and train additional medical personnel to provide specialized care to critically ill patients.5,6 Virtual ICU visits were also implemented across many ICUs. ICU nurses reported high levels of burnout, driven by staff shortages, fear of infection, and inconsistent protocols. 7 The pandemic resulted in increased efficiency in ICU workflow and resource utilization.
Physical Redesign
During the early surge of COVID-19, many hospital facilities had to get creative with accommodating the sudden increase in the volume of patients who not only passed through the emergency room (ER) but needed a higher level of care than was obtainable in a regular medicine ward. 8 ER-ICUs were created and in some hospitals, ER physicians trained in critical care were deployed to manage patients who due to crowded traditional facilities spent prolonged times in the ER. 9
In health institutions in New York where patient volume increased dramatically, roadmaps were developed and guidelines instituted to cope with the >200% increase in the demand on ICU beds. Non-ICU staff were deployed to open new ICU units and cross-collaborations across specialties occurred to ensure smooth running of these units. 10 At the lead author's facility during fellowship training, anesthetists and surgeons headed these ICUs, while critical care nurses, ICU fellows, and third-year internal medicine residents were brought in to supervise the non-ICU staff.
One of the concerns raised with the sudden and rapid expansion of ICUs was the safety and clinical outcomes of patients admitted into the expanded ICUs. Basem et al 11 in a retrospective chart review looked at patient level outcomes of expanded ICUs at New York-Presbyterian/Weill Cornell Medical Center. During the surge, operating rooms (ORs) and post anesthesia care units (PACUs) were repurposed as ICU spaces. Although ICU length of stay and mechanical ventilation duration were longer, mortality rates were actually lower, and discharge rates were comparable to traditional ICUs showing that expanded ICUs can provide safe effective patient care during crises. The expansion process brought with it certain challenges. It affected the mobilization of personnel, logistic supply and the physical structures in many hospitals. There was a strain on the provision of medical gas due to the high oxygen requirements of COVID-19 patients in many facilities.
The New York-Presbyterian/Columbia University Irving Medical Center (NYP-Columbia) converted 23 ORs into an 82-bed ICU in response to the expectations of a large volume of COVID-19 patients in the NY area. In an article describing the hospital's experience, 12 there were structural challenges with the creation of negative pressure rooms in a typical positive pressure environment, difficulties with ensuring an adequate supply of medical gas, and problems with providing plumbing associated with the effluent from continuous renal replacement therapy (CRRT) machines. Other issues identified included proper patient cohorting, maintaining privacy and personnel issues. Despite these challenges, mortality rates remained comparable to similar centers during the same period.
Negative Pressure Rooms
Negative pressure rooms are designed with ventilation systems that allow a unidirectional flow of air, typically from outside the room to inside, to prevent airborne particles from leaving the room. 13 Prior to the COVID-19 pandemic, patients with infectious diseases such as tuberculosis, Middle Eastern Respiratory Syndrome (MERS), and varicella were placed in these rooms to prevent the spread of infection to other patients and healthcare providers. The CDC has strict engineering guidelines that must be met for a negative pressure room to be designated as an isolation room suitable for preventing the transmission of airborne particles. 14
In 1993, Fraser et al 15 conducted a multi-hospital surveillance study in St. Louis and found that only 3.4% of the 3574 hospital rooms were designed for negative pressure ventilation. Nearly half of those rooms had faulty airflow, allowing air to leak into corridors. The authors concluded that even high-risk areas like ICUs often lacked proper isolation capacity, and ventilation systems were rarely tested.
Despite these early warnings, many hospitals remained underprepared for airborne threats well into the twenty-first century. When the COVID-19 pandemic emerged in 2020, few institutions had the negative pressure capacity needed to manage large numbers of infectious patients safely.
A 2022 survey of U.S. academic hospitals found that only 17% used negative pressure rooms for all COVID-19 patients, and 26% did not routinely use them at all. 16 In response to these urgent demands, hospitals began retrofitting existing ICU and non-ICU spaces to create functional airborne infection isolation areas. A 2024 study from an Italian hospital demonstrated that such retrofits significantly improved containment, boosting air clearance from 45% to 81% and eliminating measurable droplet escape. 17
An example of adapting non-traditional spaces into ICUs for infectious disease treatment is the deployment of the US Navy hospital ship, USNS Comfort, to New York City during the early COVID-19 surge. Over a 30-day mission, the ship treated 182 patients, including both COVID-positive and negative individuals. 18 To mitigate viral spread, an air circulation system with recirculation through HEPA filters was developed in rooms managing COVID-positive patients, 14 while the ship's team also re-engineered airflow and isolated COVID-positive wards from the rest of the vessel. 18 Strict precautions, including N95 use and procedural safeguards, were effective. Of note, none of the airway team tested positive for the virus.
Gas Supply
During the COVID-19 pandemic, oxygen demand rose sharply, especially in ICUs treating patients with respiratory failure. Hospitals with older infrastructure, such as limited oxygen outlets, aging piping systems, and smaller cryogenic storage, struggled to meet the surge. 19 In Brazil, hospitals with outdated pipeline systems experienced unsafe pressure drops under increased flow demand, limiting their ability to add outlets or scale capacity. 20 In the United Kingdom (UK), the Health Services Safety Investigations Body (HSIB) 21 reported that some hospitals had sufficient liquid oxygen but were unable to deliver it effectively due to constraints within their Medical Gas Pipeline Systems (MGPS). As a result, hospitals with newer infrastructure were able to expand their ICUs more easily, while those with older systems could not scale up care as easily.
Personnel
Oakley et al. in the UK 22 adopted the “Long Shops” assembly line method in the production of traction engines to ensure smooth running of the ICU during the COVID-19 surge. At their hospital, as well as in many others affected by the patient influx, the process of caring for patients was broken down into component parts. Staff redeployed from other areas of the hospital were assigned to perform single tasks, such as placing central and arterial lines. Intubations were performed by anesthetists, and non-ICU staff were grouped into teams responsible for proning patients with severe ARDS caused by COVID-19 and for providing updates to families. This approach allowed ICU staff to focus more on direct patient management, reducing stress and burnout while maintaining the quality of care. In the study, time to admission was shorter than prior to the pandemic. 22 Mortality rates were similar to other hospitals in the UK, and medical absenteeism was significantly reduced during this period.
Like the UK “Long Shop” model, the Society of Critical Care Medicine's (SCCM's) tiered staffing strategy helped establish efficient care models during the pandemic, particularly for managing the surge in mechanically ventilated patients. 23 The model supported ICU nurses by bringing in high-performing nurses from other units to meet staffing needs (Figure 1).
Several U.S. states, including New York, Georgia, South Carolina, Texas and Florida made public requests for healthcare workers from other parts of the US to travel to these states to help support and relieve overwhelmed healthcare workers. 24 Some states accelerated graduation of medical students from state universities and offered incentives to bolster the healthcare workforce.
Adaptive ICU Staffing Framework During COVID-19 Surges (Inspired by the SCCM Tiered Staffing Strategy). Legend: This Schematic Illustrates an ICU Staffing Framework Conceptually Based on the SCCM Tiered Staffing Model. The Design Shows how Critical Care Expertise can be Layered with Redeployed non-ICU Clinicians Under the Supervision of Trained Intensivists to Expand ICU Capacity During COVID-19 Surges. The Goal is to Optimize Patient Care, Conserve Resources, and Enable a Scalable Workforce Response in Crisis Conditions. Abbreviations: APP = Advanced Practice Provider; CAA = Certified Anesthesiologist Assistant; CRNA = Certified Registered Nurse Anesthetist; DO = Doctor of Osteopathic Medicine; ICU = Intensive Care Unit; MD = Doctor of Medicine; RT = Respiratory Therapist; SCCM = Society of Critical Care Medicine.
The model places a trained or experienced critical care physician at the apex, overseeing multiple care pyramids simultaneously. A non-ICU physician, such as an anesthesiologist, pulmonologist, surgeon, or hospitalist is inserted at the top of each pyramid to extend the intensivist's reach, working alongside APPs, respiratory therapists, CRNAs, CAAs, and pharmacists experienced in mechanical ventilation management. This structure is particularly critical given that approximately 48% of U.S. acute care hospitals have no intensivists on staff. 25
Visiting Policies
The ICU Liberation Bundle is a framework of evidence-based strategies designed to minimize delirium, improve long-term outcomes, and reduce the number of ICU days spent in coma. One of its key components is family engagement and empowerment. 26 During the COVID-19 pandemic, this aspect was significantly disrupted by strict infection prevention and control policies implemented in many hospitals, which prevented family members from visiting their loved ones in the ICU. The absence of family presence at the bedside, normally essential for patient advocacy and emotional support, contributed to poorer outcomes among patients admitted for COVID-related complications. 27 Patients experienced worsening physical and mental health, while families faced increased anxiety.
A study conducted in Spain examined family satisfaction scores using the validated EMPATHIC-F questionnaire across two ICUs during the pre-pandemic and early pandemic periods. The study found a decrease in median satisfaction scores in both ICUs, but the decrease was significant only in the ICU with more restrictive visiting changes. 28 Throughout the pandemic, visitation policies ranged from “no visitors allowed” to “visitation under extreme circumstances”, with more leniency introduced as COVID-19 admissions declined. 29 A study by Iness et al. 30 argued that such restrictive visitation policies could have been avoided if a more patient-centered approach had been adopted.
Many facilities introduced means to communicate with families when restrictive visiting policies were in place, which led to new innovations in the ICU around family engagement. Virtual ICU visiting facilities were implemented for families of patients unable to visit their loved ones due to the restricted hospital visiting policies and lockdown injunctions all over the world. 31 Examples included video calls facilitated by bedside nurses, which enabled families to see their loved ones if intubated or speak to and encourage loved ones who were able to hold a conversation, Technologies such as webcams, Microsoft Teams, and Zoom were also used for family updates and for communication between healthcare teams in different quarantined areas of the hospital. In addition, virtual platforms supported staff training, including orientation sessions and morbidity and mortality meetings, which could no longer take place in person.
Innovations
The COVID-19 pandemic accelerated a wave of ICU innovations, some improvised under urgent conditions, others gradually integrated into long-term practice. The urgent need for ICU beds early in the pandemic led to the expansion of existing ICU spaces, the conversion of new areas within hospital facilities, and in some cases, the establishment of ICU spaces outside the hospital. 32 Expansion efforts included reopening unused beds, increasing room occupancy, and transferring lower-acuity ICU patients to non-ICU units. 32 Some single ICU rooms were converted into double rooms, allowing one nurse to manage two patients and conserving both personal protective equipment (PPE) and staffing resources. In states experiencing severe bed shortages, systems were put in place to transfer patients to available ICUs, sometimes across time zones and state lines. 33
The SCCM's guidance on configuring ICUs in the COVID-19 era identifies key changes that were adopted during COVID-19 that helped minimize staff exposure and conservation of PPE and should be used as a template for future epidemics. These included the relocation of infusion pumps for medication administration, power cords and monitors outside patient rooms, webcams for indirect observation and glass panels placed in wooden doors for direct patient observation. Medications could then be administered without repeated room entry. It, however, requires nurse training and liaising with the pharmacy department, to prevent errors of incorrect dose administration as the use of longer lengths of tubing, potentially affects drug concentration and delivery. Adopting the use of concentrated solutions to reduce the number of times medication bags need to be changed also allows for a reduction in patient contact and monitoring, significantly reducing healthcare worker exposure risk. 34
Another key innovation was the expanded use of Telemedicine-ICU (Tele-ICU) services. 35 Although these services existed before the pandemic, their adoption had been limited. The onset of COVID-19 led to an unprecedented increase in their use. Tele-ICU services included virtual consultations, rounding, monitoring, and family visitation, as discussed above.
The pandemic also brought into sharp focus an important distinction between two related but fundamentally different concepts: remote monitoring and remote control/management of ICU devices. Remote monitoring is the ability to view patient data, ventilator settings, and alarms from outside the room, and this was widely adopted as discussed above. Remote control/management goes a step further, enabling clinicians to actively adjust device settings without entering the patient's room. This capability was largely unavailable at the onset of the pandemic and still remains in its infancy.
A study described one of the few real-world deployments of remote ventilator management during COVID-19, this FDA Emergency Use Authorization-approved technology allowed respiratory therapists to remotely adjust ventilator settings from nursing stations outside patient rooms, and was deployed across 17 patients with COVID-19 respiratory failure. The system proved feasible but revealed significant challenges, including complex informatics workflows and the need for extensive staff training. The authors emphasized that safe remote ventilator management requires direct line of sight into the patient's room, robust monitoring, and clearly defined protocols mandating periodic in-person assessments. 36 New technologies addressing remote control are in early developmental phases in the clinical space with some promising work already underway. Future ICU design will need to thoughtfully incorporate both remote monitoring and remote management, with clear protocols governing when each is appropriate. These adaptations, from physical redesigns to tele-ICU systems, are summarized in Table 1, which links each innovation to the problems it addressed and the outcomes achieved.
ICU Staffing
In a 2013 paper, Vincent identified adequate staffing as a key challenge for future ICU expansion, 37 a prediction that proved true during the COVID-19 pandemic. The rapid increase in patient volume and expansion of ICU bed capacity exposed glaring shortfalls in the number of available intensivists and nurses. All staffing cadres were impacted.
Travel healthcare staff became essential to meet workforce needs during the pandemic. However, incentives and attractive salaries significantly increased the cost of care delivery. Many hospitals operated at a financial loss, with some forced to shut down ICUs and transfer patients to other facilities. 38
Nursing shortages disrupted pre-pandemic staffing models and had lasting effects on workforce structure and staff welfare. The pandemic caused a mass of exodus of staff, resulting in a major shift in institutional history. 39 Experienced nurses responsible for training new ICU nurses departed in large numbers. As a result, nurses from other units were rapidly onboarded within weeks rather than the usual months, raising concerns about patient safety and how the ICU of the future will be designed. 40
The departure of staff was precipitated by the early, unsuccessful efforts to adequately control the pandemic, 41 leading to healthcare workers becoming infected and subsequently quarantined or placed on mandatory medical leave. The resulting active understaffing decimated shift rotations for doctors and nurses, with most healthcare workers forced to work multiple or extended shifts to cover the shortfall. This had a significant impact on staff morale and largely contributed to the burnout experienced during this period.39,40
The pandemic also disrupted the supply chain for essential drugs, medical devices, and PPE. In the early months, widespread PPE shortages resulted in preventable illness and death among frontline workers. The U.S. national strategic stockpile of masks had not been replenished since the 2009 H1N1 pandemic, leading to an inadequate supply of masks during this COVID-19 crisis. 42
A shortage of mechanical ventilators led to ethical issues about deciding which patients got assigned a ventilator versus noninvasive ventilation. There were critical shortages of essential components needed for manufacturing drugs due to a breakdown in the supply chain in countries severely affected by COVID-19. These disruptions affected the day-to-day functioning of ICUs worldwide, ultimately compromising patient care and contributing to increased morbidity and mortality.
Pandemic Readiness and Future-Proofing Critical Care Systems
The urgency of the COVID-19 crisis prompted hospitals to make swift decisions, often with limited guidance, strained resources, and inconsistent infrastructure. As ICUs became the epicenter of care, the gaps in preparedness became painfully clear, from staffing shortages and delayed licensing to equipment scarcity and unclear surge protocols.
Table 2 summarizes key challenges encountered during the pandemic, alongside actionable strategies and the potential long-term benefits of implementing them. However, beyond these tabled recommendations, it is critical to emphasize what hospitals and health systems can start doing now to better prepare for future crises.
Challenges Encountered During the COVID-19 Pandemic and Proposed Solutions for Future Preparedness.
Investing in scalable technology platforms like tele-ICU, stockpiling ethically approved multi-patient ventilator adapters, and creating modular room designs that allow for rapid conversion to negative pressure isolation are all examples of innovations born out of necessity during the pandemic. These tools should not remain experimental or emergency-only; they must be incorporated into long-term emergency planning.
Equally important are the immediate steps that don’t require massive funding include establishing licensing reciprocity across states, integrating epidemic preparedness into medical education, and maintaining transparent supply chain audits at local and state levels.
The strategies summarized in Table 2 reflect lessons learned from the pandemic and offer practical steps that institutions can adopt now to improve readiness for future emergencies. Table 1 complements this by highlighting the innovations that addressed acute gaps in capacity, infection control, and staffing, emphasizing the need for their continued integration into ICU preparedness planning.
Conclusion
Change is inevitable but some events create a seismic shift in the status quo. The COVID-19 pandemic's impact was far-reaching and resulted in changes in the way ICUs are run. It has helped this generation of ICU medical staff be prepared for pandemics in a way that no other illnesses have. ICUs are now better equipped to manage a large influx of patients, communicate with families under restricted conditions, and implement structural changes quickly when needed.
Footnotes
Acknowledgments
N/A.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.