Emergency War Surgery NATO Handbook: Part II: Response of the Body to Wounding: Chapter XI: Infection
United States Department of Defense
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Shock due to uncontrolled infection in a surgical patient requires prompt identification and treatment of the septic process. Control of infection by surgical debridement or drainage and the use of specific antibiotics represents definitive therapy. An attempt to identify the primary site of infection should be made upon diagnosis of this condition. If the source of infection is amenable to surgical control, this should be carried out expeditiously as soon as the patient's condition is sufficiently stable. Broad spectrum antibiotic therapy is initiated and based upon likely infectious organisms. A typical treatment regimen consists of triple antibiotics, such as ampicillin, gentamicin, and clindamycin. Repletion of the intravascular volume with a physiologic crystalloid solution is generally recommended. Some authors advocate infusion of colioid-containing fluid to replace intravascular volume deficits. Since an increase in pulmonary capillary permeability accompanies septic shock, attempts to replete volume with colloidcontaining fluid in this condition may result in a detrimental increase in extravascular pulmonary water.
Fluid therapy is best managed with the use of Swan-Ganz catheter monitoring of pulmonary artery wedge pressures and cardiac output. Insertion of a Foley catheter for measurement of the hourly urine output is also necessary. Many patients with sepsis and shock will develop pulmonary insufficiency necessitating endotracheal intubation and assisted ventilation. Inadequate tissue oxygenation is a consistent factor in shock, and therefore efforts to maintain a normal oxygen hemoglobin dissociation curve should be undertaken. Alkalosis, decreased pCO2, decreased hemoglobin concentration, decreased 2, 3-diphosphoglycerate, and the presence of carboxyhemoglobin are all factors which increase the affinity of the hemoglobin molecule for oxygen and thereby inhibit delivery of oxygen to tissue.
Vasoconstrictive drugs are seldom used to raise blood pressure as they have a deleterious effect upon tissue blood flow. Agents such as epinephrine and norepinephrine support the circulation by a combination of a beta 1 adrenergic cardiac effect and alpha 1 adrenergic peripheral vasoconstrictive effect. The usual dose of epinephrine is 0.5 mg IV. Norepinephrine is usually administered in the form of a continuous intravenous infusion of D5W containing 8 mg per liter at a rate of 2-3 cc per minute or higher if needed to achieve the desired hemodynamic effect. These agents are used only when volumerestorative measures have failed to provide adequate blood pressure to perfuse vital organs. When volume-restorative measures are ineffective, low dose dopamine infusion may be helpful in maintaining renal perfusion, but only as an adjunct to fluid infusion. Dopamine is thought to dilate renal and splanchnic vasculature by its action on the dopaminergic receptors. The usual intravenous "renal" dose of dopamine is 3-5 mg/kg/min given as D5W containing 200 mg/250 ml. This dosage can be increased for beta I adrenergic cardiac stimulation, and when given in doses greater than 10 mg/kg/min, commonly causes alpha stimulation and vasoconstriction that provide additional hemodynamic support in a deteriorating patient.
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