A coma is a state of prolonged unconsciousness where an individual is unable to respond to their environment or perform voluntary actions, including the basic act of eating. Despite this deep state of unawareness, the body’s metabolic functions continue, meaning the patient still requires a steady supply of calories, protein, and hydration. Since natural ingestion is impossible, medical intervention through artificial feeding is necessary to prevent rapid malnutrition. Physicians use various techniques to ensure adequate caloric and fluid intake, which are broadly categorized based on the patient’s condition and the anticipated duration of unconsciousness.
Short-Term Enteral Feeding Methods
When a coma patient is expected to recover consciousness relatively quickly and has a functioning digestive system, nutrition is delivered through temporary tubes in a process called enteral feeding. The most common method involves the use of a Nasogastric (NG) tube, a thin, flexible tube inserted through the patient’s nostril, down the esophagus, and into the stomach. This placement is typically done at the bedside and is non-surgical.
An alternative is the Orogastric (OG) tube, which is placed similarly but enters through the mouth instead of the nose; this is sometimes preferred for patients with certain facial injuries. These tubes allow for the delivery of a liquid nutritional formula directly into the stomach, where normal digestion and absorption can still occur. However, these naso- or orogastric routes are generally used for periods shorter than four to six weeks, as prolonged use increases the risk of irritation and other complications.
Long-Term Access and Specialized Delivery
For patients anticipated to remain in a comatose or vegetative state for an extended period, a more permanent form of enteral access is required. The primary method is the Percutaneous Endoscopic Gastrostomy (PEG) tube, often referred to as a G-tube. This tube is placed during a minor endoscopic procedure where a small incision is made in the abdominal wall to create a direct route into the stomach.
The PEG tube is more comfortable for long-term care than a tube running through the nose or mouth, and it carries a lower risk of dislodgement. In cases where the stomach cannot tolerate the feeding formula, such as due to delayed emptying or high risk of reflux, a tube can be placed beyond the stomach. This is done using a Jejunostomy (J-tube), which extends into the jejunum, bypassing the stomach entirely to ensure nutrient delivery and reduce the chance of aspiration.
Total Parenteral Nutrition: Bypassing the Gut
If the patient’s gastrointestinal tract is compromised, non-functional, or requires complete rest due to severe illness or injury, they cannot safely use enteral feeding. This necessitates the use of Total Parenteral Nutrition (TPN). TPN involves delivering all necessary nutrients directly into the bloodstream, completely bypassing the digestive process.
A specialized liquid solution, containing proteins (amino acids), fats (lipid emulsions), carbohydrates (dextrose), vitamins, and minerals, is infused intravenously. This infusion is administered through a central venous catheter, or central line, placed into a large vein, often in the neck or chest. TPN is used only when necessary because it carries a higher risk of complications, such as bloodstream infection, compared to gut-based feeding.
Managing Nutrition and Preventing Complications
The nutritional management of a coma patient demands continuous monitoring and specialized care to ensure safety and effectiveness. Dietitians calculate the patient’s caloric and protein requirements, which are often elevated after a severe injury, to formulate the exact liquid diet. This formula is tailored to the patient’s specific metabolic needs and adjusted based on the patient’s weight, bloodwork, and clinical status.
A primary concern with enteral feeding is preventing aspiration—the inhalation of stomach contents into the lungs, which can lead to pneumonia. To mitigate this risk, patients are kept in a semi-recumbent position, and nurses check for Gastric Residual Volume (GRV) to assess feeding tolerance. For patients receiving TPN, metabolic disturbances are a risk, requiring frequent monitoring of blood glucose levels, liver function, and electrolytes to prevent issues like refeeding syndrome.