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44 JUNE 2015 | EMSWORLD.com pressures, as the gravid uterus prevents nor- mal, unobstructed diaphragm movement. In addition, obstructed diaphragm movement also results in a decrease in tidal volume, requiring smaller tidal volumes and a higher respiratory rate to achieve an adequate min- ute volume. Patients who present in the field with acute, severe hypertension secondary to HELLP syndrome may be candidates for treatment with antihypertensives depend- ing on factors such as clinical presentation, the availability of antihypertensive agents and transport times. While there is no stan- dard, various sources suggest initiating anti- hypertensive medications in patients with systolic blood pressures greater than 160 or 170 mmHg and signs of end-organ failure such as headache, visual disturbances, AMS, chest discomfort or AMI and pulmonary edema. 13 Regarding specific antihypertensive agents, a 2013 Cochrane review of drugs for treatment of high blood pressure in pregnancy concluded that the "choice of antihypertensive should depend on the clinician's experience and familiarity with a particular drug, with consideration of its adverse effects and patient preferences." It also said nimodipine, diazoxide and ket- anserin were probably best avoided. 14 That said, the average paramedic will most likely have one antihypertensive drug available in their formulary, and will have limited experience and familiarity with using it in pregnant females with hypertension. Accordingly, medical control should be consulted prior to the administration of any antihypertensive medication in a pregnant or postpartum female. Options for specific antihypertensives in the prehospital environment include labet- alol, hydralazine and magnesium sulfate. Hydralazine is a smooth muscle relaxant and often considered the drug of choice for initial blood pressure care because it has no effect on a patient's heart rate or respiratory rate. Typically hydralazine is administered IV in 10–20 mg doses over five minutes and can be repeated once. Magnesium sulfate is another good option. However, it requires an initial 2–6-gram IV bolus administered over 20–30 minutes. This requires the use of an IV pump to ensure it's not delivered too fast. A rapid magnesium infusion is likely to cause hypotension as well as depression of the patient's respirations and mental state, and can lead to flaccid paralysis and death. The onset of seizures in the patient with suspected HELLP syndrome should be managed with 2 grams IV magnesium sulfate administered over 5–10 minutes; this has been shown to be more effective than benzodiazepines for prevention of recurrent seizures. 13,15 Magnesium sulfate should not only be used to treat active sei- zures but with the permission of medical control can also be administered as seizure prophylaxis in patients with HELLP syn- drome. The suggested dosing regimens for magnesium sulfate vary, with loading doses ranging from 4–6 grams IV over 30 minutes and maintenance doses from 1–3 grams per hour. A common regimen involves a loading dose of 6 grams IV over 20–30 minutes fol- lowed by 2 grams per hour as a continuous infusion. 13 Recurrent seizures in patients receiving magnesium sulfate prophylaxis can be treated with an additional 2 grams of the drug administered over 5–10 minutes. Providers administering magnesium sulfate should be familiar with the signs and symptoms of hypermagnesemia. Mild hypermagnesemia can manifest with diminished deep tendon reflexes, headache, lethargy, drowsiness, nausea and f lushing. Moderate hypermagnesemia can present with absent deep tendon reflexes, somnolence, ECG changes, bra- dycardia and hypotension. Severe hypermagnesemia will progress to paralysis, respiratory failure and apnea, heart block and car- diac arrest. Proper kidney function is impor- tant in maintaining appropriate plasma magnesium concentra- tions, so pay particular attention to patients with renal insufficiency or failure. Patients with mild to mod- erate kidney disease can be treated with the administration of normal saline and a loop diuretic such as furosemide. Patients with kidney CONTINUING EDUCATION For More Information Circle 36 on Reader Service Card PROVIDERS ADMINISTERING MAGNESIUM SULFATE SHOULD BE FAMILIAR WITH THE SIGNS AND SYMPTOMS OF HYPERMAGNESEMIA.