Rumack-Matthew nomogram
Encyclopedia
The Rumack-Matthew nomogram , also known as Rumack-Matthews nomogram or the Acetaminophen nomogram is an acetaminophen toxicity nomogram plotting serum concentration of acetaminophen against the time since the onset of ingestion in an attempt to prognosticate possible liver toxicity as well as allowing a clinican to decide whether to proceed with N-Acetylcysteine (NAC) treatment or not. It is a logarithmic graph starting not from the immediate onset of ingestion, but from 4 hours post ingestion after absorption is considered likely to be complete.
In hands of skilled clinicans this nomogram allows for timely management of acetaminophen overdose. Generally, a serum plasma concentration (APAP) of 140-150 microgram/mL (or milligrams/L) at 4 hours post ingestion, indicates the need for NAC treatment. This nomogram is not used alone if the patient has altered mental status or if the history is not reliable. Rather, a second level should be drawn and plotted to see if the slope of the line remains at or above the nomogram. A formal half life may also be determined. Measure at time (t=0) upon admission of the patient to the emergency room, and a blood value at time (t=4 hrs) should be obtained and half-life
calculated. If half-life is more than 4 hours, then treatment is necessary to prevent hepatotoxicity and liver failure.
The original line starting at 200 microgram/mL at 4 hours was published in 1975 by Rumack BH. and Matthew H. When the NAC study was begun in 1976, the FDA required a line that was 25% below the original line now called the treatment line. The study line which is now referred to as the treatment line was created starting at 150 at 4 hours and is the usual line used in the United States to determine treatment of acetaminophen overdose. This was published in 1981.
In hands of skilled clinicans this nomogram allows for timely management of acetaminophen overdose. Generally, a serum plasma concentration (APAP) of 140-150 microgram/mL (or milligrams/L) at 4 hours post ingestion, indicates the need for NAC treatment. This nomogram is not used alone if the patient has altered mental status or if the history is not reliable. Rather, a second level should be drawn and plotted to see if the slope of the line remains at or above the nomogram. A formal half life may also be determined. Measure at time (t=0) upon admission of the patient to the emergency room, and a blood value at time (t=4 hrs) should be obtained and half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
calculated. If half-life is more than 4 hours, then treatment is necessary to prevent hepatotoxicity and liver failure.
The original line starting at 200 microgram/mL at 4 hours was published in 1975 by Rumack BH. and Matthew H. When the NAC study was begun in 1976, the FDA required a line that was 25% below the original line now called the treatment line. The study line which is now referred to as the treatment line was created starting at 150 at 4 hours and is the usual line used in the United States to determine treatment of acetaminophen overdose. This was published in 1981.