Lactulose is a synthetic sugar medication used primarily to treat acute hepatic encephalopathy. This severe complication of liver disease occurs when toxins, particularly ammonia, build up and affect brain function. Rectal administration is a high-stakes procedure reserved for patients who cannot take the medication orally due to an altered mental state or risk of aspiration, or when rapid reduction of blood ammonia levels is necessary. This method delivers a large dose directly to the colon, the primary site of action for ammonia removal.
Essential Supplies and Preparation
Preparing for the enema requires gathering specific items to ensure a safe and effective procedure.
- Concentrated lactulose solution
- Sterile water or normal saline for dilution
- A large syringe (typically 60 mL)
- A rectal administration kit, including a catheter or tubing
- Water-based lubricant
- Disposable gloves, absorbent pads, and a clean mixing container
The concentrated lactulose solution must be precisely diluted to create the retention enema. The standard mixture is 300 mL of lactulose combined with 700 mL of water or normal saline, resulting in a one-liter volume. This large volume ensures the solution reaches far enough into the colon for maximum therapeutic effect. Warming the diluted solution slightly to body temperature (around 37°C) increases patient comfort and reduces the likelihood of cramping, which could cause premature expulsion. Cleansing enemas containing alkaline agents, such as soapsuds, must be avoided before administration.
Step-by-Step Rectal Administration Procedure
The patient must first be positioned to maximize the flow and retention of the fluid within the colon. The preferred position is the left lateral recumbent position, often called the Sims’ position. In this position, the patient lies on their left side with the right knee drawn up toward the chest, allowing the fluid to flow more easily into the sigmoid and descending colon.
Before insertion, apply a generous amount of water-soluble lubricant to the tip of the rectal catheter or tubing to ease passage and prevent mucosal irritation. Insert the catheter gently and slowly into the rectum, typically to a depth of two to four inches, following the natural angle. If resistance or patient discomfort occurs, pause and reposition the catheter slightly.
The diluted lactulose solution is then infused slowly through the catheter or tubing. Slow infusion minimizes cramping and improves retention; a rapid infusion can trigger the urge to expel the liquid immediately, undermining effectiveness. Once the entire one-liter volume has been administered, the catheter should be slowly and carefully withdrawn.
Post-Procedure Monitoring and Retention
Following administration, the patient must attempt to retain the enema for 30 to 60 minutes to allow the medication to work effectively. This duration is needed for colonic bacteria to break down the lactulose, which lowers the pH and traps the ammonia for eventual excretion.
To encourage retention, applying gentle pressure to the patient’s buttocks may be helpful, particularly if they are uncooperative or have reduced sphincter control. If the enema is expelled prematurely (retained for less than 30 minutes), the entire dose may need to be repeated immediately to achieve the therapeutic goal. The expected outcome is a rapid, large bowel movement that flushes the trapped ammonia out of the body, reversing the symptoms of encephalopathy.
The patient’s mental status and vital signs should be closely monitored throughout the post-procedure period. While improvement may be seen within two hours, the treatment aims to reverse the acute state so the patient can transition back to oral lactulose. Immediate medical attention is necessary if the patient experiences severe abdominal pain, difficulty breathing, or signs of severe dehydration or electrolyte imbalance, which are potential side effects of aggressive laxative therapy.