Paroxysmal Supraventricular Tachycardia
The simplest method to convert paroxysmal supraventricular tachycardia (PSVT) is to use vagal maneuvers. However, if the patient is unstable, cardiovert immediately if that option is available. Use either saline pads or the same gels as used for ultrasound examinations.
The Valsalva maneuver, bearing down against a closed glottis, is consistently the most effective vagotonic technique. Its efficacy can be increased by pressing firmly over the right hypochondrium (over the liver) while the patient exhales and bears down. This increases venous return to the right side of the heart and augments the effect on cardiac stretch receptors, thereby increasing the chance of successfully terminating the arrhythmia.2
Stimulating the diving reflex works best on children. Ask children who are old enough to cooperate to hold their breath and dunk their face into a pan of ice water resting on their lap. Do not force their head into the water or hold it under! For younger children, have a parent hold a towel that has been dipped in ice water over the child's face—while keeping the airway clear.
Pressor drugs can occasionally terminate AV nodal reentry by inducing reflex vagal stimulation mediated by baroreceptors in the carotid sinus and aorta. This requires the systolic blood pressure (BP) to be elevated to about 180 mm Hg, so should be used carefully or not at all in the elderly or in patients who have structural heart disease, significant hypertension, hyperthyroidism, or an acute myocardial infarction. Given over 1 to 3 minutes, the adult doses for these agents are phenylephrine 1%, 1 mg (0.1 mL) to 10 mg (1 mL); methoxamine, 3 mg to 5 mg; or metaraminol, 0.5 mg to 2.0 mg. If edrophonium is used, administer it over 15 to 30 seconds—it is very short acting.
Ineffective Congestive Heart Failure Treatments
To have improvised methods to treat pulmonary edema accompanying heart failure would be superb. The hallmark of treatment is preload reduction, that is, reducing the volume of blood entering the heart. You may think that some old treatment methods might work in austere situations; they don't.
"Congesting cuffs" or "rotating tourniquets" were often applied to the extremities to treat patients with acute pulmonary edema secondary to left heart failure. The theory was that rotating tourniquets would provide some benefit until medications could be administered. They don't work.3–5
Practiced since biblical times, the removal of volumes of blood to treat heart failure continued into the late 20th century. Unfortunately, the technique also has been shown to be ineffective except in patients with hemochromatosis or polycythemia.
Both the catheters and the manometers used for central venous pressure (CVP) monitoring are disposable, but, if necessary, they can be boiled (disinfected) and reused. The danger in reusing catheters is that particulate matter may remain within them, so the disinfection may not be effective.6
For measuring CVP, attach a manometer to either a 3-way stopcock or a sterile "Y" tube. A manometer can readily be constructed from another intravenous set taped over or beside an upright ruler or cardboard marked in centimeter increments. The manometer is filled from the intravenous bottle and then connected via a central line to the patient. Any drip going through the line is stopped. The zero point is the mid-axillary line with the patient in a supine position.7 (The normal reading is 5 to 10 cm H2O.)
To be accurate, the zero ("0") mark on the CVP manometer must be level with the supine patient's mid-axillary line. Use a long piece of wood with a level taped on top, so you can check that it is parallel with the floor. Place one end of the wood at the patient's mid-axillary line and, while watching the level, attach the CVP manometer to an IV pole so that the zero ("0") is even with the wood's other end. An alternative is to use a piece of IV tubing that has been half-filled with colored water and then formed into a loop by connecting the two ends. The two menisci (where the water meets the air) in the tube will always be at the same level if the loop is held vertically. Figure 10-3 illustrates how to use such a tube to adjust the manometer height.6
Makeshift CVP monitor with leveling loop.
Developed by Dr. Robert Jones to help treat fractures, the Jones compression dressing also effectively eliminates edema caused by systemic problems such as chronic venous insufficiency, lymphedema, and other illnesses causing lower extremity swelling.8 However, since the dressing does not treat the underlying problems, when possible, these should also be treated.
To make your own compression dressing, apply three to five rolls of 4-inch cast padding, or equivalent material, with minimal compression: Going distal to proximal creates a pressure gradient that permits the swelling to increase. Over these layers, wrap a 6-inch elastic bandage, again in a distal to proximal manner so that it also creates a compression gradient. With severe edema, place cotton between the toes.
Repeat the padding layer with three to five more padding rolls followed by another 6-inch elastic bandage. Apply each layer with increasing tightness to maintain the compression gradient effect. The result is that each layer is applied with greater pressure distally and less pressure proximally. A layer of plaster can be added if additional support is needed. If plaster is added as a splint, it is generally not used posteriorly.
Change the dressing every 5 to 7 days. When used for a fracture, this dressing virtually eliminates the need to remove a cast that becomes "too tight." However, burning or numbness with application may indicate tissue ischemia. If that occurs, remove the dressing and reapply it.