Pritchard regimen of Magnesium sulphate: How to give MgSO4 in Eclampsia

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Pritchard regimen is a type of treatment protocol used in the management of Eclampsia and severe preeclampsia by use of magnesium sulphate (MgSO4). The Pritchard regimen is commonlyused than other regimens such as the Zuspan regimen and Sokoto regimen in the control of Severe Preeclampsia and Eclampsia. The Pritchard regimen does not cure Eclampsia but is used for the control of convulsions before delivery of the fetus. The cure or permanent treatment to Eclampsia is delivery of the baby. Pritchard regimen helps to buy time for delivery to occur.

Pritchard regimen of Magnesium Sulphate in the control of Eclampsia(How to give MgSO4 in Eclampsia)

  1. 14g of Magnesium sulphate is given as loading dose: 4g out of the 14g is given intravenously while the remaining 10g is given intramuscularly the 10g is divided into 5g each and given into the buttocks of the patient. The 4g given intravenously is diluted before being given because MgSO4 is very painful when given and it is given slowly over 15 minutes.
  2. 5g of Magnesium sulphate is given as Maintenance dose: 5g of MgSO4 is then given every 4 hours when the first 5g is given in the left buttock, then the second 5g is given in the right buttock (4 hours after the first dose). This 5g of MgSO4 is given continuously into alternate buttocks until 24 hours after the last episode of convulsion or 24 hours after delivery of the baby. This is what is referred as the Pritchard regimen.
  3. 2g of Magnesium sulphate is given again as part of the Loading dose ONLY when there is recurrent convulsion . This is also given slowly over 15 minutes and it is only given if there is no sign of toxicity after the initial 14g loading dose.
A bottle of MgSO4 (50% in 10ml): this is equivalent to 5g in 10ml.
A bottle of MgSO4 (50% in 10ml): this is equivalent to 5g in 10ml.


Dilution of Magnesium sulphate before being given intravenously

Magnesium sulphate should be diluted to a strength of 20% or less before being given intravenously because it is very painful it is for this reason that the drug is given slowly over 15 minutes because patients cannot withstand it when the drug is administered within a short period. It can even cause inflammation of the veins (thrombophlebitis). There are different strengths of MgSO4: 50% in 10mls, 40mg etc. 50% in 10mls of MgSO4 means there are 5g in the 50ml.

For the intramuscular dose: this is usually added with 1 ml of 2% lidocaine to reduce the pain.NEVER add lidocaine to the intravenous dose of Magnesium sulphate because it can arrest the heart and the patient may die from it. Only the intramuscular dose is being added with lidocaine. If you are unsure of this, it is better for the patient to feel pains than to die.

Monitoring when using the Pritchard regimen

  1. Monitor patellar tendon reflex: this should be tested to ensure it is present. It is the first sign of MgSO4 toxicity to appear before others. Absence of this shows there is toxicity and magnesium sulfate should be stopped before other signs appear.
  2. Monitor the respiratory rate before giving the MgSO4 and after every dose of MgSO4. The reason for this is simple: magnesium sulphate is capable of depressing respiration. For this reason, anytime you give magnesium sulfate either intramuscularly or intravenously, do ensure to count the respiratory rate before giving the next dose. Respiratory rate should be above 12 cycles per minute. Any value below this shows toxicity and MgSO4 should be stopped immediately and Calcium gluconate given.
  3. Monitor the urine Output: when giving magnesium sulphate in the Pritchard regimen, always pass a urethral catheter with a urine bag attached in order to monitor the urine output of the patient. Whenever you come to give the next dose of MgSO4, always note and record the urine volume. This is important because when acute renal failure occurs, it can be noted and the regimen can be stopped. The urine output should be more than 25mls per hour or more than 100mls every 4 hours. Any volume of urine lower than this shows toxicity and MgSO4 should be stopped and Calcium gluconate should be given.

Magnesium sulphate Toxicity in Pritchard regimen

  1. Depression of respiration
  2. Loss of deep tendon reflexes (Loss of knee jerk reflex)
  3. Slurred speech
  4. Acute renal failure

Antidote to Magnesium sulphate Toxicity in the use of Pritchard regimen

  1. Intravenous Calcium gluconate (10mls of 10% given slowly over 10 to 15 minutes)
  2. Intravenous Calcium chloride (10mls of 10% given slowly over 10 to 15 minutes)

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