Tourniquet

When administering a drug into a vein by a venipuncture, tiie nurse should place a tourniquet above the selected vein. It is important to tighten the tourniquet so that venous blood flow is blocked but arterial blood flow is not. The nurse should allow the veins to fill (distend) and then should pull tiie skin taut (to anchor the vein and the skin) and insert tiie needle into tiie vein, bevel up, and at a short angle to tiie skin. Blood should immediately flow into the syringe if tiie needle is properly inserted into the vein. 

Epinephrine is widely used in clinical medicine for its multiple pharmacologic effects particularly for its potent vasoconstrictor effects. For example, in a dilute solution of 1 100,000, it provides a surgical tourniquet and facilitates a blood-free operating field. It is administered by nebulizer and face mask for post-intubation croup and for viral croup. 

Patterson, S. and Klenerman, L. (1979). The effect of pneumatic tourniquets on the ultrastructure of skeletal muscle. J. Bone Joint Surg. 61B, 178-183. 

Correct timing of antibiotic administration is imperative to preventing SSI. The National Surgical Infection Prevention Project recommends infusing antimicrobials for surgical prophylaxis within 60 minutes of the first incision. Exceptions to this rule are fluoroquinolones and vancomycin, which can be infused 120 minutes prior to avoid infusion-related reactions.1 No consensus has been reached on whether the infusion should be complete prior to the first incision. However, if a proximal tourniquet is used, antibiotic administration should be complete prior to inflation. 

Trousseau s sign An indication of latent tetany in which carpal spasm occurs when the upper arm is compressed, as by a tourniquet or a blood pressure cuff. 

Administer the antihistamine diphenhydramine (Benadryl, adults 25-50 mg children 1-2 mg/kg) usually given parenterally. Apply tourniquet proximal to site of antigen injection remove every 10-15 minutes. 

The rate of absorption from an SC injection site may be retarded by immobilization of the limb, local cooling to cause vasoconstriction, or application of a tourniquet proximal to the injection site to block the superficial venous drainage and lymphatic flow. In small amounts, adrenergic stimulants, such as epinephrine, will constrict the local blood vessels and, therefore, slow systemic absorption. Conversely, cholinergic stimulants (such as methacholine) will induce very rapid systemic absorption subcutaneously. Other agents may also alter their own rate of absorption by affecting local blood supply or capillary permeability. 

Epinephrine 1 1000, 0.2 to 0.5 mg (0.2 to 0.5 mL) SC is the primary treatment. In children, administer 0.01 mg/kg or 0.1 mg. Doses may be repeated every 5 to 15 minutes if needed. A succession of small doses is more effective and less dangerous than a single large dose. Additionally, 0.1 mg may be introduced into an injection site where the offending drug was administered. If appropriate, the use of a tourniquet above the site of injection of the causative agent may slow its absorption and distribution. However, remove or loosen the tourniquet every 10 to 15 minutes to maintain circulation. 

The usefulness of diuretics in the management of CHF cannot be overstated. Before diuretics were available, rotating tourniquets were used to diminish venous return by ligating the lower extremities. Less venous blood returned to the right side of the heart and pooled in the legs. This procedure diminished the effective intravascular volume that would otherwise have accumulated in the lungs. The availability of loop diuretics (particularly furosemide) has resulted in the virtual elimination of this practice. 

Excellent and rapid anesthetization of an extremity can be obtained easily. Following insertion of an intravenous catheter in the limb of interest, a rubber bandage is used to force blood out of the limb, and a tourniquet is applied to prevent the blood from reentering a dilute solution of local anesthetic, most commonly lido-caine, is then injected intravenously. This technique fills the limb s vasculature and carries the anesthetic solution to the nerve by means of the blood supply. Because of the pain produced by a tourniquet after some time, this procedure usually is limited to less than 1 hour. The systemic blood levels of drug achieved after tourniquet release generally remain below toxic levels. 

Intravenous regional anesthesia—injection of local anesthetic into a suitable vein supplying the limb to be anesthetized the blood flow from this limb is then restricted by a tourniquet... 

Studies have shown that emergency field remedies such as incision and suction, tourniquets, and ice packs are far more damaging than useful. Avoidance of unnecessary motion, on the other hand, does help to limit the spread of the venom. Definitive therapy relies on intravenous antivenin and should be started as soon as possible. 

Rasmussen K, Mailer J, Lyngbak M (1999) Within person variation of plasma homocysteine and effects of posture and tourniquet application. Clin Chem 45 1850-1855... 

Blood sampling (venipuncture) must be performed without tourniquet, venestasis or muscular hand activity. Use of a catheter is recommended. Once the catheter (Cathelon Critikon, Tampa, Florida, USA) is installed, the first milliliter (1 to 2 volumes of the catheter) should be discarded before a blood sample is taken. 

J.W. Gooch, Biocompatible Polymeric Materials and Tourniquets for Wounds, Topics in Applied Chemistry, DOI 10.1007/978-1-4419-6586-8 l,... 

A safe and effective combat tourniquet should possess the following properties as learned from these studies and experiences shared by the US Army medical personnel... 

Force applying to tourniquet must be convenient for the injured soldier under any physical conditions including laying in fox hole or other position... 

Option for automatic tourniquet adjustment using battery-powered pneumatic bladder... 

The above conditions were satisfied with a ratchet-buckle and single flexible 1.5 inch strap. The force capable of being applied through the lever-ratchet mechanism provided more than enough force from thumb or fingers to tourniquet any size limb. The strap was stressed so that it formed a bow shape in the center and formed the favorable round shape that is preferable for decreasing strain on tissue and nerves. The ratchet-buckle consisted of spikes to penetrate a fiber-woven belt that was very successful in defeating mud, sand, and blood, example shown in Fig. 1.3. 

J.W. Gooch, Biocompatible Polymeric Materials and Tourniquets for Wounds, 91... 

On the battlefield, a properly applied tourniquet can be an extremely effective means of controlling severe extremity wound hemorrhage. However, a great deal of confusion exists among soldiers, medics, and military medical officers on a number of tourniquet-related issues. What is an appropriate combat tourniquet When is it appropriate to use a tourniquet When and by whom should a tourniquet be removed Under what conditions should a tourniquet not be released or removed What are the most effective ways to increase limb salvage while using a tourniquet ... 

The technical definition of a tourniquet is any device that is used to prevent blood from flowing through blood vessels below the placement of the tourniquet on either upper or lower limbs. A tourniquet prevents excessive loss of blood from a limb wound with the expectation of saving a life. On the battlefield, the tourniquet in one form or another has been used to control excessive hemorrhaging on nonvital extremities since the Roman Empire days, where a rope or cloth strap was used for toumiqueting a soldier s limb that has suffered a wound. The use of tourniquets has always been as controversial as it has been successful. This controversy results, as will be described later, as much from mistakes made in the application and release of the tourniquet as it does from the primitive design of the most commonly used tourniquets of today. 

Fig. 5.1 Tourniquet edge-effect pressure for narrow and wide belt tourniquets...

Because of the fear of tourniquet-related limb damage, tourniquets are almost never used in civilian trauma cases and have been discouraged since World War II by many militaries due to the amputations suffered by soldiers when tourniquets were left on too long or over tightened. This practice was kept in place even though many if not most trauma specialists believed that if properly used, tourniquets saved lives. It was not until modem battlefield casualty studies were made that the need for tourniquets was reevaluated. 

Analysis of the data from the current conflicts in Afghanistan and Iraq shows that the increased frequency of field tourniquets in treating traumatic limb injuries has contributed to lower mortality due to battlefield injuries. This was accomplished with extremely low rates of tourniquet-induced complications. Contributing to the low rate of complications was the personnel training in the treatment of extremity injuries. The analysis further indicated that all battlefield personnel should carry tourniquets and that they should be carried directly on their person and not stowed in their vehicle, back packs, or other equipment bags. 

---