In the ICU blood tests are usually done at least twice a day. They measure such things as how the kidneys are working, cardiac markers (to make sure the heart is healthy) and levels of potassium (K+) and other elements. These are some of the indicators of how the body is working and can show the intensive care specialist how well a patient’s body is coping with their illness. Intra-arterial and intravenous lines (tubes placed in arteries and veins) are often used to monitor the body and, once established, allow rapid, reliable and pain-free access for repeated blood tests. Some conditions will require multiple repeated blood testing every few hours.

A patient with critical illness will commonly develop problems with their heart and circulation. Various factors are involved, some related to the primary disease while others are secondary effects. Problems include changes in: the distribution and volume of body fluid, the condition of the blood vessels and the ability of the heart to pump blood around the body. Treatment for cardiovascular problems may include fluid therapy and a wide range of medicines to control the heart rate, heart function and blood pressure.

Respiratory failure occurs when the respiratory system is no longer able to provide enough oxygen requirements or remove enough carbon dioxide from the body. Hypoxia (not enough oxygen is reaching the tissues) may occur unless there are interventions. Large amounts of carbon dioxide may also build up in respiratory failure. Mechanical Ventilation This is the use of a ventilator (breathing machine) to do the breathing for a patient experiencing respiratory failure. The ventilator fills the lungs with air, thereby providing oxygen to, and removing carbon dioxide from, the body via the lungs. Usually the ventilator delivers oxygen directly into the airway of the patient. This is done using an endotracheal tube which is a plastic tube that is passed through the mouth into the top of the trachea (windpipe). Conscious patients are usually given a medication to make them sleepy or unconscious and a muscle relaxant to help them relax while the tube is inserted. Sometimes people may require a ventilator for a long time. If this is the case a tracheostomy (when an opening is made in the trachea through the front of the neck) is performed and the endotracheal tube inserted into the opening. For many very ill patients mechanical ventilation lasting only hours or a few days is enough and, after normal breathing is established, the ventilator can be removed. Noninvasive Positive Pressure Ventilation Some patients may receive ventilation without needing intubation, with the breathing support being delivered via a sealed mask applied to the face. However noninvasive ventilation is useful only in some circumstances and in some patients. Acute Respiratory Distress Syndrome (ARDS) This is a life-threatening condition. It results from any illness that causes widespread inflammation of the lungs. In ARDS, fluid builds up in the air sacs of the lungs (alveoli) and other lung tissue. When the air sacs fill with fluid, the lungs can no longer fill properly with air and the lungs become stiff. This makes breathing difficult. The main symptom of ARDS is severe shortness of breath. This may develop within minutes or gradually over a few days. A doctor may confirm a diagnosis of ARDS by: a chest x-ray arterial blood gas analysis, which measures the oxygen levels in blood. Treatment depends on the underlying cause but may include a breathing machine (mechanical ventilation) until the lungs heal.

A nasogastric tube is often inserted at the same time as the endotracheal tube. The nasogastric tube is inserted into the stomach via the nose. This tube helps to ensure that the patient receives the necessary nutrition while they are in the Intensive Care Unit.

Kidney (or renal) failure is when a patient’s kidneys are unable to remove wastes and excess fluid from the blood. The likelihood that the kidneys will get better depends on what caused the kidney failure. Kidney failure is divided into two general categories, acute and chronic. In acute (or sudden) kidney failure, when kidneys stop functioning due to a sudden stress, they might be able to start working again. However, when the damage to the kidneys has been continuous and has worsened over a number of years, as in chronic renal failure (CRF), then the kidneys often do not get better. When CRF has progressed to end stage renal disease (ESRD), it is considered irreversible or unable to be cured. There are a number of causes of acute renal failure and in intensive care patients there is often more than one factor that contributes to its development.