Life support refers to medical treatments and procedures designed to sustain the body’s fundamental functions when a patient’s own organs are failing. These interventions are temporary measures, intended to support life until the body can recover or until definitive treatment for the underlying condition can be provided. When illness, injury, or major surgery compromises the body’s ability to maintain processes like breathing, circulation, or waste removal, life support machinery and medications step in. The goal is to stabilize the patient, giving their body time to heal.
Assisting Respiration and Oxygenation
When a patient can no longer breathe adequately, mechanical ventilation is the primary form of respiratory life support. This process involves a machine that generates positive pressure to push air into the lungs, ensuring the body receives enough oxygen while removing carbon dioxide. Support is delivered in two main ways: invasively or non-invasively.
Invasive ventilation requires a tube, called an endotracheal tube, to be inserted into the trachea, a procedure known as intubation. This method offers the most precise control over oxygen delivery and protects the airway, but it typically requires the patient to be sedated. Non-invasive ventilation uses a tight-fitting mask placed over the nose and mouth, allowing the patient to remain awake and avoid the risks associated with intubation.
For patients whose lungs are severely damaged and cannot be supported by a traditional ventilator, Extracorporeal Membrane Oxygenation (ECMO) may be used. ECMO acts as an external heart-lung machine, pumping blood out of the body and passing it through an oxygenator, which functions as an artificial lung. This process adds oxygen to the blood and removes carbon dioxide before the blood is returned to the patient. ECMO allows the patient’s heart and lungs to rest completely, providing a bridge to recovery or to a transplant.
Maintaining Circulation and Blood Pressure
Circulatory support is necessary when the body’s mechanisms for maintaining adequate blood pressure fail, a state often referred to as shock. Maintaining sufficient blood pressure is paramount because it ensures that all vital organs, including the brain and kidneys, receive the necessary blood flow, or perfusion, to function. Medications called vasoactive agents are the primary tool for this support, administered continuously through intravenous pumps.
These medications include vasopressors and inotropes, which work on the cardiovascular system in distinct ways. Vasopressors, such as norepinephrine or vasopressin, function by causing the blood vessels to constrict, which directly increases blood pressure. Inotropes, like dobutamine, work by increasing the strength of the heart’s muscle contractions, improving the amount of blood the heart pumps out with each beat. These two classes of drugs are often used together to achieve the ideal balance of vessel constriction and heart pumping power to stabilize the patient’s hemodynamics.
The overall aim of this pharmacological support is to keep the mean arterial pressure (MAP) above a certain threshold, typically 65 mmHg, which is the minimum pressure needed for adequate organ perfusion. By managing blood pressure and heart function, these medications prevent the failure of other organs that rely on a steady supply of oxygenated blood. The drugs are highly potent and fast-acting, requiring continuous monitoring and careful titration by medical staff to ensure the patient receives the lowest effective dose.
Replacing Kidney Function
Acute kidney injury is a common complication in severe illness, where the kidneys suddenly lose their ability to filter waste products and manage fluid balance. When this happens, dialysis is required to artificially take over the kidneys’ critical roles, preventing the buildup of toxins like urea and creatinine in the bloodstream. In the intensive care setting, Continuous Renal Replacement Therapy (CRRT) is often the preferred method of support.
CRRT is a gentle, non-stop process that runs continuously over 24 hours, making it better tolerated by critically ill patients who may have unstable blood pressure. The machine uses a special filter, known as a hemofilter or dialyzer, to draw blood out of the body and circulate it through a circuit. Inside the filter, waste products and excess fluid are removed through diffusion and ultrafiltration before the cleaned blood is returned to the patient.
This continuous filtration cleanses the blood of uremic toxins, controls the patient’s fluid status, and maintains the balance of electrolytes. CRRT provides the necessary time for the injured kidneys to potentially recover their function without the body being overwhelmed by fluid overload or dangerous chemical imbalances.
Delivering Essential Hydration and Nutrition
Patients receiving life support are often too sick or sedated to safely eat or drink, making artificial nutritional support a necessity. Providing energy and building blocks is a component of life support, as the body needs fuel to power organ function and initiate healing. Two main pathways are used to deliver these nutrients: enteral and parenteral feeding.
Enteral nutrition is the preferred method when the patient’s gastrointestinal tract is still functioning, as it helps maintain the health of the gut lining. This involves delivering a liquid formula, containing carbohydrates, proteins, fats, vitamins, and minerals, directly into the stomach or small intestine through a feeding tube.
When the gut cannot be safely used due to injury or dysfunction, parenteral nutrition is implemented. Total Parenteral Nutrition (TPN) bypasses the digestive system entirely by delivering a formulated solution of nutrients directly into the bloodstream through an intravenous line. This ensures the patient receives necessary calories, proteins, and micronutrients to prevent malnutrition and support recovery.