The Intensive Care Unit

Original Editor - Chidile Muonwe

Top Contributors - Merinda Rodseth, Kim Jackson, Tarina van der Stockt, Ewa Jaraczewska, Uchechukwu Chukwuemeka and Lucinda hampton  

Introduction

Intensive care represents the highest level of patient care and treatment designated for critically ill patients with potentially recoverable life-threatening conditions. The Centers for Medicare & Medicaid Services defines critical illness or injury as “acutely impairing one or more vital organ systems such that there is a high probability of imminent or life-threatening deterioration in the patient’s condition”. Intensive care (critical care) is a multidisciplinary and interprofessional speciality specifically designed for the management of patients at risk of developing or with established, life-threatening organ failure. The capacity to temporarily support and, if necessary, replace the function of many failing organ systems, particularly the lungs, cardiovascular system and kidneys, is what underscores intensive care medicine.

The Intensive Care Unit (ICU) is a separate, self-contained area within a medical facility, equipped with high-tech specialised facilities designed for close monitoring, rapid intervention and often extended treatment of patients with acute organ dysfunction. It is committed to the management and continuous monitoring of patients with life-threatening conditions. intensive care aims to maintain vital functions to prevent further physiological deterioration, reduce mortality and prevent morbidity in critically ill patients. Provision of intensive care is within the continuum of primary, secondary and tertiary care, with the majority of these services delivered in the secondary-care setting.

Types of Intensive Care Units (ICUs)

Intensive care units can be organised based on the pathologies/conditions treated (e.g. neurological, trauma, burns, medical or surgical ICUs) or by the age group of the patient admitted (adult or paediatric). Specialized intensive care units include medical, surgical, pediatric and neonatal intensive care units.

Medical intensive care unit

The medical intensive care unit is dedicated to caring for adult patients with medical conditions requiring frequent observation, specialized monitoring and medical treatment. These include illnesses such as diabetic ketoacidosis, gastrointestinal bleeding, drug overdose, respiratory failure, sepsis, stroke and cancer.

Surgical intensive care unit

The surgical intensive care unit is dedicated to managing postoperative patients, including patients who have undergone major abdominal surgeries, craniotomy patients, thoracotomy patients, unstable multiple trauma patients and any surgical patient who requires continuous monitoring or life support.

Pediatric intensive care unit

Critically ill children are managed in the paediatric intensive care unit. Children who have just undergone surgery and are at risk of deterioration are also managed in the pediatric intensive care unit.

Neonatal intensive care unit

The neonatal intensive care unit is responsible for managing premature, high-risk and critically ill infants. Neonates with congenital disorders and birth complications are also managed in the neonatal intensive care unit.

Many other types of ICUs exist, for example, coronary units, burns units, trauma ICUs, mixed ICUs and out-of-hospital ICUs (mobile ICUs).

ICU Equipment

Equipment in the ICU is mostly aimed at life-support and the support of different organs in the body (for example, the lungs, the heart or the kidneys). These include, but are not limited to:

• Cardiac monitors - to monitor vital signs
• Mechanical ventilator
• Infusion pumps - to regulate the flow of medication titrated via a drip and through the infusion pump
• Syringe pumps - where a syringe is used to titrate the medication to the patient
• Suction machines
• Oxygen
• Other respiratory support machines such as BiPAP and CPAP

Indications for ICU admission

Intensive care resources are limited and expensive, and therefore patients should be carefully selected for admission to ICU. Two patient categories have been identified as not to benefit from ICU care, these are described as being "too well to benefit" and "too sick to benefit" from critical care services. The specialist intensivist should make the decision to admit a patient to the ICU in agreement with the referring team, and it should be based on the severity of the illness, chronic health and physiology reserve, and therapeutic susceptibility as well as being informed by the wishes of patients or caregivers.

Many factors contribute to the triage decisions made for admission into ICU. One classification suggests the factors to be contextual, patient and physician-related.

• Contextual factors include characteristics of the ICU, for example, the current availability of beds, appropriate equipment and expertise of the nursing staff.
• Patient factors refer to the characteristics of the patient such as their preferences, functional capacity, age and comorbidities, as well as the characteristics of the illness with regards to severity, reversibility, responsiveness to therapy and quality of life after discharge from ICU.
• Physician factors refer to the characteristics of the person making the decision, including experience, personality, mood and biases.

Even though admission criteria may vary between ICUs and from country to country, universal criteria have been recommended for patient admission into the ICU. Following their prioritization model, the Society of Critical Care Medicine (SCCM) categorised patients into four priority level groups in their guidelines for ICU triage. These groups are based on how likely the patients are to benefit from admission to the ICU and can be found in the table below:

Priority level	Description
Priority 1	No therapeutic limits Critically ill unstable patients in need of intensive treatment and monitoring that cannot be provided outside the ICU High probability of recovery
Priority 2	No therapeutic limits Require intensive monitoring May potentially need immediate intervention Lower probability of recovery
Priority 3	Critically ill Reduced likelihood of recovery because of underlying disease or the nature of their acute illness Have therapeutic limitations
Priority 4	Generally not appropriate for ICU admission because of: low risk of active intervention that could not safely be administered in a non-ICU setting and therefore is anticipated to have little benefit from ICU care Terminal/irreversible illness and facing imminent death

Table 1: ICU Admission Prioritization Levels

The SCCM also provided some diagnoses and parameters for ICU admission in their previous guidelines for ICU admission, based on their diagnosis and the objective parameters models. A list of these has been provided in the table below. Currently, there is, however no conclusive evidence informing ICU admission criteria.

System	Condition
Cardiac System	Acute myocardial infarction with complications Cardiogenic shock Complex arrhythmias requiring close monitoring and intervention Acute congestive heart failure with respiratory failure and/or requiring hemodynamic support Hypertensive emergencies Unstable angina, particularly with dysrhythmias, hemodynamic instability, or persistent chest pain S/P cardiac arrest Cardiac tamponade or constriction with hemodynamic instability Dissecting aortic aneurysms Complete heart block
Respiratory system	Acute respiratory failure requiring ventilatory support Pulmonary embolism with hemodynamic instability Patients in an intermediate care unit who are demonstrating the respiratory deterioration Need for nursing/respiratory care not available in lesser care areas such as the floor or intermediate care unit Massive hemoptysis Respiratory failure with imminent intubation
Neurologic system	Acute stroke with altered mental status Coma: metabolic, toxic, or anoxic Intracranial haemorrhage with potential for herniation Acute subarachnoid haemorrhage Meningitis with altered mental status or respiratory compromise Central nervous system or neuromuscular disorders with deteriorating neurologic or pulmonary function Status epilepticus Braindead or potentially brain-dead patients who are being aggressively managed while determining organ donation status Vasospasm Patients with a severe head injury
Drug Ingestion and Drug Overdose	Hemodynamically unstable drug ingestion Drug ingestion with significantly altered mental status with inadequate airway protection Seizures following drug ingestion
Gastrointestinal Disorders	Life-threatening gastrointestinal bleeding, including hypotension, angina, continued bleeding, or comorbid conditions Fulminant hepatic failure Severe pancreatitis Oesophageal perforation with or without mediastinitis
Endocrine	Diabetic ketoacidosis, complicated by hemodynamic instability, altered mental status, respiratory insufficiency, or severe acidosis Thyroid storm or myxedema coma with hemodynamic instability Hyperosmolar state with coma and/or hemodynamic instability Other endocrine problems, such as adrenal crises with hemodynamic instability Severe hypercalcemia with altered mental status, requiring hemodynamic monitoring Hypo or hypernatremia with seizures, altered mental status Hypo or hypermagnesemia with hemodynamic compromise or dysrhythmias Hypo or hyperkalemia with dysrhythmias or muscular weakness Hypophosphatemia with muscular weakness
Surgical	Post-operative patients requiring hemodynamic monitoring/ventilatory support or extensive nursing care
Others	Septic shock with hemodynamic instability Hemodynamic monitoring Clinical conditions requiring ICU-level nursing care Environmental injuries (lightning, near drowning, hypo/hyperthermia) New/experimental therapies with potential for complications Vital Signs * Pulse < 40 or > 150 beats/minute * Systolic arterial pressure < 80 mm Hg or 20 mm Hg below the patient's usual pressure * Mean arterial pressure < 60 mm Hg * Diastolic arterial pressure > 120 mm Hg * Respiratory rate > 35 breaths/minute Laboratory Values (newly discovered) * Serum sodium < 110 mEq/L or > 170 mEq/L * Serum potassium < 2.0 mEq/L or > 7.0 mEq/L * PaO2 < 50 mm Hg * pH < 7.1 or > 7.7 * Serum glucose > 800 mg/dl * Serum calcium > 15 mg/dl * Toxic level of drug or other chemical substance in a hemodynamically or neurologically compromised patient Radiography/Ultrasonography/Tomography (newly discovered) * Cerebrovascular haemorrhage, contusion or subarachnoid haemorrhage with altered mental status or focal neurological signs * Ruptured viscera, bladder, liver, oesophageal varices or uterus with hemodynamic instability * Dissecting aortic aneurysm Electrocardiogram * Myocardial infarction with complex arrhythmias, hemodynamic instability or congestive heart failure * Sustained ventricular tachycardia or ventricular fibrillation * Complete heart block with hemodynamic instability Physical Findings (acute onset) * Unequal pupils in an unconscious patient * Burns covering > 10% BSA * Anuria * Airway obstruction * Coma * Continuous seizures * Cyanosis * Cardiac tamponade

Table 2: Indication for ICU admission. Adopted from the European Critical Care Society Guideline for ICU admission.

Why Commence Physiotherapy Early in the ICU?

Physiotherapy is one of the principals and most consistent therapy services for Critical Care. Physiotherapists (PTs) carry out individualized assessments of patients admitted to the ICU to identify the needs of each patient.

The risk for muscle weakness, delirium and prolonged mechanical ventilation is increased in ICU patients because of their physical inactivity. These complications can eventually lead to physical and cognitive impairments, which could last for years after discharge from the ICU. PTs play a vital role in the prevention and management of respiratory disorders as well as the prevention and management of musculoskeletal and neuromuscular disorders in both intubated and spontaneously breathing patients in the ICU.

Early mobilisation and physical rehabilitation are considered paramount to the recovery of critically ill patients in the ICU. Evidence exists that it is safe and at low risk for adverse events and that it: Early mobilisation protocols include mobilisations and exercises. They can progress from the passive mobilisation of limbs and postural changes to ambulation and basic everyday activities.

• Improves physical functioning
• Decreases ICU acquired weakness
• Decreases the duration of mechanical ventilation
• Decreases the length of stay in the ICU

Early physiotherapy for patients in the ICU is also necessary to mitigate other complications that might arise, such as ICU delirium, ventilator-associated pneumonia, and ICU-acquired neuropathy/myopathies among others.

Resources

• Richard Hollingham. How intensive care units were born [Internet]. BBC Future. 2020. [Accessed 6 February 2021].