An effective IRCU requires clearly defined areas and appropriately equipped spaces to support care, monitoring, and respiratory support for semicritical patients. Architectural guidelines mainly derive from ICUs and describe two main models: open-plan layouts and individual patient rooms, with some mixed approaches.

Open-plan layouts enhance staff efficiency and situational awareness, facilitating early recognition of clinical deterioration and rehabilitation in certain patient populations [3,4]. However, they may increase the risk of multidrug-resistant cross-infections, requiring strong infection-control measures [5]. Room-based layouts provide environmental control, support noisy NIV, and allow family presence, but require compensatory monitoring systems. Patients and relatives generally report higher satisfaction in room-based units, whereas staff may experience higher levels of stress and isolation [6,7]. Room-based layouts also facilitate humanization strategies beyond family presence, such as access to clocks, television, and personal hygiene or bathing facilities, which support patient orientation, preserve circadian rhythms, and help reduce depersonalization and delirium [8].

Unit size should also be considered. Recommendations from other countries suggest a maximum of 10 beds [9], although in practice capacity can vary widely and often responds to epidemiological pressures, as observed in Spain, where the mean number of IRCU beds increased from 4 to 14 during the COVID-19 pandemic [10]. Potential needs for isolation rooms equipped with negative pressure should also be considered during unit design.

Increasing technological complexity, including noninvasive support devices and continuous monitoring, reinforces the need for well-planned spaces that ensure safety, visibility, and efficient workflow, because inadequate design can compromise infection control, emergency response, and ultimately clinical outcomes.

Monitoring and noninvasive support therapies form the structural and functional backbone of any IRCU. Monitoring involves the continuous or intermittent measurement of physiological parameters, performed remotely and with sufficient resolution to detect alarm thresholds and enough variability to support clinical decision-making. In addition, IRCUs must be equipped to perform essential respiratory procedures and safely deliver noninvasive ventilatory support.

For this reason, every IRCU should provide at least basic patient monitoring, essential respiratory therapies, and procedural capabilities, whereas more advanced interventions may be available according to unit expertise. Table 1 summarizes the essential (basic) and advanced/excellence monitoring variables, procedures, and support therapies that should be available in an IRCU.

Architecturally, regardless of whether patients are in direct view or not, the unit must include a centralized monitoring center to minimize delays in detecting clinical deterioration and optimize rapid response to procedural or ventilatory needs.

The respiratory support therapies employed in an IRCU – both invasive and noninvasive – include NIV, invasive ventilation, HFNC, continuous positive airway pressure (CPAP), and mechanical insufflation–exsufflation (MI-E). These therapies must be approved for use in critically ill patients, capable of delivering inspired oxygen fractions close to 100%, and able to maintain operational autonomy during patient transfers or power outages. As in ICUs, it is also essential for these units to have an independent power generator and a dedicated oxygen supply to ensure uninterrupted therapy. All devices should be user-friendly and compatible with various consumables. Ventilators, in particular, must support continuous monitoring of key respiratory parameters, such as real-time flow, pressure, and volume curves [11]. Their use also requires specific infrastructural support, including oxygen and medical air outlets, high-capacity humidification systems, and adequate space for device placement and handling. A robust vacuum outlet is essential for secretion suctioning. Given the high risk of aerosol generation, SEPAR highlights the importance of appropriate ventilation systems, preferably with negative pressure or high air-exchange rates.

Once monitoring is integrated with respiratory therapy devices, frequent evaluation of device performance and patient–ventilator interaction is crucial in the IRCU. Continuous patient surveillance and assessment of treatment tolerance, proper equipment setup, detection of leaks, upper airway events, and patient–ventilator asynchronies are all essential for adjusting parameters and preventing potential harm to respiratory mechanics. Additionally, multiparametric scales with high predictive value for therapeutic failure – such as the Acute Physiology and Chronic Health Evaluation II (APACHE II), the Heart rate, Acidosis, Consciousness, Oxygenation, and Respiratory rate (HACOR) score, the Respiratory Rate-Oxygenation (ROX) index, and the Noninvasive Ventilation Outcomes (NIVO) score – can be used to guide clinical decision-making.

The staffing of an IRCU should consist of a multidisciplinary team including, at minimum, physicians, nurses, nursing assistants, and respiratory physiotherapists. When appropriate, consultation with professionals from other services or units should be available to address specific patient needs, such as nutritionists, pharmacists, speech therapists, and psychologists. This collaborative structure ensures comprehensive care tailored to the diverse clinical requirements of semicritical respiratory patients [9].

All professionals working in the unit must be trained in critical respiratory care and airway management, as well as in the monitoring and use of equipment commonly employed in the IRCU, including vital signs monitors, NIV devices, HFNC systems, secretion suction devices, and the management and replacement of tracheostomy cannulas [9,12].

Following recommendations from several national and international scientific societies, IRCUs should be staffed with 1 physician for every 6 patients. However, this ratio should be adjusted according to patient complexity, with increased availability for tracheostomized or highly complex patients. This physician is typically the attending pulmonologist acting as unit coordinator, and continuous coverage, 24h a day, 7 days a week, should be ensured [12–14].

Nursing care should be provided at a ratio of 1 nurse for every 4 patients (1:4), also available 24h a day, 7 days a week, with the possibility of improving this ratio when patient severity or complexity so requires (e.g., patients with neuromuscular disease or those undergoing initiation or weaning of NIV or HFNC) [12,13,15–17]. Complementing nursing care, 1 nursing assistant for every 4 patients should be present around the clock, with additional support allocated according to patient needs.

Respiratory physiotherapy should be ensured by 1 physiotherapist for every 6 patients, delivering 1 session daily throughout the week and offering additional afternoon sessions for patients with higher requirements, such as difficulty optimizing gas exchange, managing bronchial secretions, or reduced mobility. The physiotherapist's role encompasses both respiratory therapy and patient mobilization to enhance autonomy and functional recovery [12,17]. Finally, to support continuity of care and ensure a familiar environment, family members or the primary caregiver are encouraged to remain in the patient's room.

Fig. 1 graphically summarizes the architectural, technological, and staffing characteristics that an IRCU should meet.

Fig. 1.

Graphical summary of the architectural, technological and staffing characteristics that a respiratory intermediate care unit (IRCU) should meet.

Currently, there are no nationally recognized documents, structured training pathways, or official certification programs for healthcare professionals working in intermediate- or semicritical-care units in Spain. In the absence of a regulated framework, it is necessary to analyze training models from countries where comparable levels of care are formally defined and regulated to identify reference standards and best practices that could inform future national strategies. Table 2 provides an overview of the main requirements identified in countries with an established tradition in respiratory intermediate care [1,15–26].

In addition, SEPAR has established a voluntary accreditation system for IRCUs, with approximately 30 Spanish hospitals currently accredited. Units are classified into three levels: basic units, specialized units, and highly specialized units. The geographical distribution of accredited units is heterogeneous, with a higher concentration in major metropolitan areas such as Madrid, Barcelona, and Valencia [18].

The proposed training framework for Spain is structured into three progressive levels applicable to all IRCU healthcare professionals. Rather than establishing rigid time-based requirements, this framework adopts a competency-based model with flexible itineraries, combining modular clinical rotations in accredited units, high-fidelity simulation training, and direct skill assessment and accreditation. This approach is better suited to the diversity of professional profiles and career trajectories within the Spanish healthcare system and is aligned with international frameworks such as the ERS Respiratory Critical Care HERMES project, which defines 229 verifiable competencies across knowledge levels without mandating fixed training durations.

According to the British Thoracic Society, patients most likely to benefit from a respiratory care unit include the following [12]:

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  Patients receiving acute NIV for acute hypercapnic respiratory failure with acidosis.

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  Patients receiving acute noninvasive CPAP for hypoxemic respiratory failure.

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  Patients receiving HFNC for hypoxemic respiratory failure.

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  Patients receiving long-term ventilation admitted acutely.

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  Patients with severe respiratory disease associated with intellectual disability.

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  Medical patients requiring intercostal drainage.

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  Patients with acute asthma requiring close monitoring.

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  Patients with severe acute pneumonia with risk factors for poor outcomes.

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  Patients with intermediate-high-risk or high-risk pulmonary embolism.

The model contemplates direct admission from the emergency department or conventional hospital wards in the following situations:

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  Acute respiratory failure requiring NIV or HFNC.

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  Acute exacerbation of chronic respiratory failure requiring NIV or HFNC.

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  Avoidance of ICU admission when ICU criteria are not met.

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  Need for advanced monitoring or surveillance in patients without comorbidities or hemodynamic instability that would otherwise require ICU admission.

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  Alternative to endotracheal intubation in hypoxemic respiratory failure.

The objectives of the step-up model include the following [14]:

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  Prevention of intubation: avoidance of invasive mechanical ventilation in 65–70% of cases and reduction of associated complications (nosocomial infections, ventilator-associated pneumonia, delirium, critical illness neuropathy, agitation, among others).

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  Reduction or avoidance of ICU days: shortening of average ICU length of stay.

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  Scalability: ability to expand during healthcare crises or seasonal epidemic peaks.

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  Continuity of care for complex chronic respiratory patients (e.g., COPD with frequent exacerbations or frailty criteria, bronchiectasis, chronic bronchial colonization, obesity-hypoventilation syndrome).

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  Optimization of available resources according to patients’ actual needs in a humanized care environment.

Step-down refers to the planned transfer of patients from higher-acuity units with advanced monitoring and intensive care requirements [20].

In this scenario, IRCUs have proven highly effective in several processes:

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  Management of difficult or prolonged weaning from mechanical ventilation.

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  Postextubation care for high-risk patients.

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  Postoperative care for patients with high respiratory risk or those at high risk of complications from prolonged intubation or contraindications to intubation (e.g., patients with neuromuscular disease undergoing abdominal or thoracic surgery).

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  Monitoring of high-risk patients transferred from intensive care or requiring surveillance that cannot be provided on a conventional ward, functioning as a bridging unit (e.g., following thrombectomy or fibrinolysis for pulmonary embolism).

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  Patients with a therapeutic ceiling who remain under active treatment but require a level of care or therapy unavailable on conventional wards (e.g., oncology patients with infectious, vascular, or immune-mediated respiratory complications, or patients with severe COPD requiring noninvasive respiratory support).

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  Decannulation processes: IRCUs are considered optimal settings for decannulation, reducing ICU length of stay and associated costs. Standardized and protocolized decannulation performed by a multidisciplinary team in a monitored area with adequate nurse-to-patient ratios decreases morbidity and mortality [21]. In contrast, direct transfer of these patients from the ICU to conventional wards is associated with higher mortality and multiple complications related to tracheostomy management and inadequate nurse staffing ratios, which do not meet the specific needs of these patients [15]. During the COVID-19 pandemic, more than 60% of IRCU activity in Spain was related to step-down care involving ventilator weaning and decannulation [22].

These criteria are designed for patients who no longer require multiorgan life support but whose respiratory failure or care complexity prevents transfer to a conventional ward. For transfer from the ICU to an IRCU, stability must be demonstrated in three domains while maintaining the need for respiratory support.

The IRCU serves as a dynamic pivot within the continuum of care, bridging the community, the emergency department, intensive care, conventional wards, and post-acute settings such as day hospitals or home hospitalization. Coordination with the ICU is bidirectional and guided by established protocols based on the criteria stated in Table 3.

The IRCU operates under a formalized multidisciplinary governance structure, coordinating with Cardiology, Infectious Diseases, Anesthesiology, Hematology-Oncology, Palliative Care, and central support services such as Radiology and Respiratory Therapy. Allied specialists – including Rehabilitation, Physiotherapy, Nutrition, Mental Health, Social Work, and Speech Therapy – are integrated through structured care pathways and regular multidisciplinary meetings. Clear roles, responsibilities, and coordination protocols ensure that all specialties contribute effectively to patient care during the IRCU stay and support continuity of care after discharge.

The organization and functioning of the IRCU rely on structured ward rounds with defined short- and medium-term objectives, as well as regular clinical sessions. Safety rounds should be conducted at least twice yearly. A multidisciplinary committee reviews complex cases, ensures adherence to therapeutic plans, defines therapeutic ceilings, addresses do-not-intubate orders, and includes representation from all relevant specialties, thereby ensuring comprehensive and coordinated patient care.

Finally, continuity of care after IRCU discharge is carefully structured to ensure patient safety and optimal recovery. In most cases, patients are first transferred to conventional wards, where their clinical status continues to be monitored. Coordination with outpatient respiratory clinics, home hospitalization programs, and primary care remains essential to support ongoing management.

The integrated flow model, illustrated in Fig. 2, highlights the unit's pivotal role in early admission, accelerated weaning, seamless step-down care, and coordinated escalation to ICU when necessary. Multidisciplinary governance, standardized procedures, and structured care pathways ensure high-quality care, continuous monitoring, and safe discharge planning, thereby supporting optimal patient outcomes throughout the respiratory care trajectory.

Fig. 2.

Integrated patient flow within the IRCU. The diagram illustrates the IRCU as a central pivot connecting the community, emergency department, ICU, conventional wards, and post-acute care settings.

IRCUs represent a specific level of care dedicated to the management of semicritical respiratory patients [1,23]. Their configuration as a functional management unit responds to the need to establish a specific care model with organizational autonomy and clinical leadership within hospital care pathways [10,19,24]. The functional definition of the IRCU provides clarity in patient flow, facilitates standardization of admission and discharge criteria, and allows efficient planning of human and technological resources according to patient complexity [20,25].

Additionally, this model responds to a contemporary paradigm of hospital care based on the following principles:

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  Risk stratification.

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  Stepped levels of care.

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  Proactive clinical management.

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  Efficiency and safety.

Therefore, the configuration of the IRCU as a functional management unit is not an optional organizational model but rather a structural necessity for any hospital caring for respiratory patients with clinical complexity.

Intermediate care units are not exclusive to the respiratory field. Multiple specialties have developed intermediate care structures that bridge the gap between conventional hospitalization and critical care for semicritical patients.

Coronary care units and stroke units are well-established examples managing patients with acute syndromes without invasive mechanical ventilation. These units operate with continuous monitoring, specific protocols, and clearly defined admission criteria. Their success is reflected in reduced in-hospital mortality, standardized clinical management, and optimized use of ICU beds. They function with specific nurse-to-patient ratios, ensuring patient safety without the need for sedation or advanced life support.

Recent studies have confirmed their effectiveness in both clinical outcomes and operational efficiency, consolidating their role within modern cardiologic and neurologic care [25,27–29]. Functional organization includes stable multidisciplinary teams, time-sensitive protocol-based care, and direct coordination with different hospital services, all of which have been essential to their consolidation as a quality standard in European and North American healthcare systems.

Anglo-Saxon and Scandinavian healthcare systems have developed Intermediate Care Units (IMCUs) or High Dependency Units (HDUs) for semicritical patients requiring intensive monitoring without invasive ventilation or deep sedation. These units operate with functional independence and nurse-to-patient ratios ranging from 1:2 to 1:4 and have demonstrated reductions in ICU overcrowding while improving stepped-care delivery [30,31].

These models share common structural principles with IRCUs: precise definition of the target population, functional autonomy, staffing proportional to intermediate complexity, and an approach oriented toward clinical anticipation. Their consolidation has been supported by both clinical evidence and operational efficiency.

From a healthcare management perspective, the functional model enables the development of a specific set of activity, efficiency, and outcome indicators that ensure process traceability and facilitate impact evaluation in terms of care value and system efficiency [32].

In this regard, available studies have shown that implementation of functional IRCUs is associated with a significant reduction in ICU admissions among patients with moderate respiratory failure, without compromising clinical outcomes or patient safety [10,33]. To standardize measurement of these outcomes, this document includes a dedicated chapter defining the indicators considered most representative and with the greatest measurement capacity.

From an economic standpoint, the IRCU model offers a highly favorable cost-effectiveness profile. Several studies have documented that patient care in IRCUs reduces utilization of high-complexity resources without compromising clinical safety. In a retrospective observational study conducted at a Spanish tertiary hospital (Fundación Jiménez Díaz), IRCU care significantly reduced cost per patient, amounting to €1574 per episode compared with €5869 for patients with similar clinical characteristics managed in the ICU. Moreover, no differences in in-hospital mortality were observed between the two groups, reinforcing the hypothesis that appropriate patient selection optimizes both the clinical and economic performance of IRCUs [34].

These findings are consistent with more recent experiences during the SARS-CoV-2 pandemic, in which the estimated cost per bed-day was €164 in the IRCU compared with €696 in the ICU, resulting in cumulative savings exceeding €200,000 over only 2 months of operation [35]. This cost differential is explained not only by lower staffing requirements and greater specialization but also by shorter lengths of stay, reduced pharmacologic resource consumption, and lower logistical complexity, all of which contribute to sustainability.

Economic analysis should not be limited to direct costs alone but should also incorporate a comparative perspective of different funding models and return on investment, as summarized in Table 4. Furthermore, the efficiency of IRCUs cannot be assessed exclusively in monetary terms. There are nonmonetized organizational and care-related benefits – such as improved continuity of care, reduced ICU burden, and higher satisfaction among patients and healthcare professionals – which are detailed in Table 5.

Clearly defining the structure and functions of the IRCU allows inclusion of staffing, technology, and maintenance needs in the hospital's annual budget. This facilitates justification of the necessary resources to hospital management and enables integration of the unit into hospital financing models, ensuring greater long-term stability and sustainability.

In high-demand scenarios (seasonal pressure, complex chronic respiratory diseases, or epidemic crises), the functional IRCU has proven to be an effective and cost-efficient resource [18].

Functional design enhances patient safety and quality of care by standardizing processes and ensuring continuity of complex respiratory care. Additionally, it allows formation of stable, specialized teams in noninvasive ventilation, oxygen therapy, and respiratory monitoring, thereby increasing the unit's problem-solving capacity and fostering a culture of clinical excellence, operational efficiency, and commitment to outcomes [19,23,36,37].

Once the target population has been identified, the unit's structural and operational model should be designed according to the hospital's size and complexity. The literature suggests that 4–12 beds provide an optimal balance between efficiency, quality control, and operational sustainability, although the appropriate unit size should ultimately be adapted to institutional context, case mix, and patient complexity [23]. Units that are too small risk underutilization or higher per-patient costs, whereas overly large units may dilute functional specificity and complicate clinical governance. Strategic placement near the ICU or postanesthesia care areas, together with integration within the Pulmonology service, is recommended to facilitate coordination, streamline patient flow, and ensure rapid access to critical support when needed.

The success of the model largely depends on specialized clinical leadership under the direct responsibility of the Pulmonology department, with formal competencies in critical care and advanced respiratory support. Medical coverage should be guaranteed 24h a day, 7 days a week, either through onsite staffing in large hospitals or through mixed models with telemedicine support in smaller or rural hospitals in coordination with the ICU or Anesthesiology departments [37,38]. Multidisciplinary coordination with other services – including Endocrinology, Otolaryngology, Hospital Pharmacy, Social Work, Clinical Psychology, Anesthesiology, ICU, and Emergency Medicine – is essential to ensure patient-centered care and proactively address complex needs.

Definition of structured and homogeneous admission criteria is essential to ensure appropriate utilization of the unit. Protocols should clearly define bidirectional referral flows with the ICU and Anesthesiology departments, as well as with the emergency department and other services that may require IRCU support to avoid unnecessary ICU admissions (step-up model). These pathways should align with triage systems, include dedicated electronic templates, and ensure immediate access to diagnostic tests [18,39].

An IRCU should be fully integrated into hospital information systems to enable standardized data collection and periodic analysis of key performance and outcome indicators – such as risk-adjusted mortality, avoided ICU admissions, length of stay, readmissions, and costs – within a continuous improvement framework aligned with a Learning Health System and supported by standardized clinical templates and evidence-based respiratory care algorithms [14,40,41].

The model should consider financial feasibility and medium- to long-term sustainability, integrating into the strategic plans of both the hospital and the regional healthcare system. IRCUs may be linked to integrated care strategies for complex chronic patients, hospital bed reorganization, waiting list reduction, or high-resolution admission pathways for respiratory diseases [34,42].

In hospitals with space or staffing limitations, a mixed model may be considered in which the unit shares infrastructure with other intermediate care units while maintaining its functional respiratory specificity and ensuring availability of the resources required by its patient population [9]. It is essential that IRCUs have the necessary resources to qualify for SEPAR accreditation, which requires indicators adapted to the national healthcare system and patient needs. Achievement of this accreditation implies dedicated budget allocation, inclusion in analytical accounting models, and evaluation in terms of organizational, clinical, and economic impact.

The selected indicators (Table 8) will be developed according to the proposed model (online-only supplement), incorporating established weighting criteria and following previous experiences in IRCUs using structured quality management frameworks [43]. These indicators are organized into the following categories [44].

Measurement of indicators in the IRCU must be based on a standardized framework that ensures comparability and validity. Each indicator should include a precise definition, calculation formula, data source (electronic health record, hospital discharge database, nursing records, monitoring systems), unit of measurement, and target population. Integration into the electronic health record through structured templates and mandatory fields enables automated data capture, reduces errors, ensures traceability, and facilitates multicenter analysis.

The optimal reporting frequency should balance timeliness and robustness:

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  Monthly reporting should include activity indicators (admissions, occupancy, admission/discharge ratio) and process indicators (NIV or HFNC initiation, protocol adherence, safety checklists), together with minor complications.

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  Quarterly reporting should include analysis of clinical outcomes (risk-adjusted mortality, early readmissions, NIV failure), efficiency indicators (avoided ICU admissions, adjusted length of stay), and major complications.

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  Annual reporting should evaluate strategic outcomes, temporal trends, intercenter benchmarking, and the impact on ICU workload and overall cost-effectiveness.

Data quality should be ensured through cross-validation with external databases, internal audits, and oversight by a designated quality manager responsible for detecting inconsistencies and initiating corrective actions. Periodic reports must be shared with the clinical team and discussed in multidisciplinary meetings so that the information generated becomes a driver of organizational change. This measurement and reporting framework aligns the IRCU with the principles of a Learning Health System, transforming routine monitoring into a tool that improves clinical outcomes, optimizes resource utilization, and strengthens governance [45,46].

Preparation of follow-up reports in the IRCU represents the operational mechanism through which data are transformed into a tool for management and continuous improvement. To ensure applicability across different healthcare settings, this model should be structured in a tiered manner according to the complexity level of the unit.

All levels should incorporate a mandatory core framework to ensure quality of care and patient safety, including systematic monitoring of key indicators and implementation of essential clinical-organizational algorithms, such as admission and discharge criteria, escalation protocols (IRCU-to-ICU), definition of respiratory support failure, and recording and analysis of adverse events and device-related complications [47,48].

Building on this common foundation, higher-complexity units may integrate advanced analytical tools, including risk-adjusted indicators, predictive models of respiratory support failure (e.g., HACOR and ROX indices), interhospital benchmarking, and business intelligence systems with real-time dynamic dashboards [49]. Reports should follow a standardized structure including an executive summary, analysis of key indicators, interpretation of trends, and proposed improvement actions. Recommended reporting frequency is monthly for process and activity indicators, quarterly for clinical outcomes and efficiency indicators, and annually for strategic evaluation, including cost-effectiveness analyses and external benchmarking [50].

Within a model aligned with the concept of a Learning Health System, reports should be explicitly linked to improvement plans with assigned responsibilities, defined timelines, and monitoring metrics, thereby ensuring a continuous cycle of evaluation, intervention, and reassessment [51].