Shock

Intraoperative and Postoperative Hemorrhage

In the case of massive perioperative hemorrhage, the administration/substitution of large quantities of crystalloid and colloid solution and blood products is required to maintain an adequate circulating volume with a sufficient organ and tissue perfusion.

The preparation for red blood cells is usually a leukocyte-depleted erythrocyte concentrate extracted from a whole blood donation. Another product is fresh frozen plasma (FFP), which is also extracted from a whole blood donation. FFP needs to be warmed for about 40 min at 37 °C, until it can be used. This long delay can be bridged in very urgent cases with readily available coagulation factors such as Prothrombin factor II, Proconvertin factor VII, Christmas-Factor (fac tor IX), Stuart-Prower-Factor (factor X) concentrate (PPSB), antithrombin 3 (AT III), fibrinogen, and recombinant factor VIIa. The third column ofblood component therapy are platelets, which are available as a pool concentrate from four whole blood donations or as an apheresis preparation from one donor.

Other solutions to maintain an adequate intravascu-lar volume are colloidal solutions such as hydroxyethyl starches, gelatin, and dextran, which remain for a longer period in the intravascular system. Crystalloid solutions such as ringer's lactate or normal saline have a disadvantage in severe hemorrhage in that they distribute throughout the extracellular space, e.g., to fill up 11 of lost blood 3-41 of crystalloid solution is needed for replacement.

A new approach for fluid resuscitation in severe hy-povolemic shock in emergency medicine is to combine a hypertonic solution (e.g., 7.5 % sodium chloride solution) with hyperoncotic solutions (e.g., 6% Hydroxy ethyl starch [HES]) to mobilize the interstitial fluid to

Fig. 3.4. High-flow blood and fluid warmer, System 1025, Level 1 (Level 1, Inc. 2006)

Fig. 3.4. High-flow blood and fluid warmer, System 1025, Level 1 (Level 1, Inc. 2006)

increase the intravascular volume. Since the dosage necessary is only 3-4 ml/kg of body weight in adults, this effective procedure is called small-volume resuscitation.

For the administration of fluid quantities required per time, large-bore intravenous cannulas of the highest possible diameters are useful. The diameter of appropriate peripheral cannulas is 14 gauge placed in the v. basilica or v. jugularis externa or 12-Fr catheters in the v. jugularis interna, v. subclavia, or v. femoralis. Special high-flow infusion lines and three-way-stop cocks should be used as well: because of the large diameter they allow the high required flows for fluid resuscitation. Fluid warming with special devices is advisable in order to prevent hypothermia with consecutive deterioration of the coagulation system and negative cardiac side effects. Pressure is applied to the infusion bags by compressing the infusion bags with a manually or automatically driven pressure bag. Figure 3.4 shows an example of a high-flow blood and fluid warmer, where up to 1,100 ml/min of fluid can be administered to the patient.

Anaphylaxis

The anaphylactic reaction (AR) is defined as an immediate humoral reaction due to preformed membrane-adherent immunoglobulins IgE, which lead to the release of histamine and other mediators. Anaphylaxis is the worst possible variant of an AR. The incidence for a severe intraoperative AR is 1:6,000 to 1: 28,000.

Triggers for perioperative AR include neuromuscular blocking agents (60 % - 70 %), latex (18 %), colloidal solutions (5%), barbiturates, antibiotics, opioids, protamine, ethylene oxide, blood transfusions, and methylmethacrylate (bone cement). Cross reactions such as penicillin - cephalosporin or sulfonamide -loop diuretics should be considered, as the AR to one substance may also implicate the AR to the other substance.

Symptoms and Treatment

The symptoms vary from a light cutaneous reaction (degree 0) to cardiopulmonary arrest (degree 4). Symptoms and treatment of each stage are described below.

Degree 0 is a localized cutaneous reaction (urticaria). Discontinuing of the trigger substance, reassurance, and in most cases the establishment of an intravenous line is indicated.

Degree 1 is a light general reaction with the following symptoms: disseminated cutaneous reaction (flush, pruritus, generalized urticaria), reaction of the mucous membranes, edema (nose, conjunctivitis), and general symptoms (cephalgia, restlessness, vomiting). The therapeutic measure include discontinuation of the triggering agent, reassurance, placement of an intravenous line, fluid resuscitation (500 ml), corticosteroids (e.g., 250 mg prednisolone), and antihistaminics (e.g., 0.1 mg/kg dimethindene in combination with 5 mg/kg cimetidine).

Degree 2 is a pronounced general reaction (pulmonary and/or cardiovascular reaction), dysregulation of the circulatory system (tachycardia, hypotension, arrhythmias), Quincke edema, laryngeal edema, dyspnea, beginning bronchospasm, and urge for defecation and urination. The treatment consists of the discontinuation of the allergen, intubation, and mechanical ventilation in good time, intravenous line and fluid resuscitation (500-1,000 ml). Epinephrine should be administered in boluses of 5 - 50 |g i.v., corticosteroids and antihistaminics should be administered as described above, and bronchospasmolytics be administered as needed (inhalative beta-2-mimetics such as terbutaline, fenoterol, salbutamol, and intravenous theophylline 5 mg/kg i.v.).

Degree 3 is characterized by a general reaction with shock, bronchospasm, and unconsciousness. In addition to the measures taken in degree 2 anaphylactic reactions, mechanical ventilation should be provided with 100% oxygen, fluid resuscitation with 1,000-2,000 ml crystalloid and colloid solution, epinephrine (initial bolus 5-100 |g, followed by continuous infusion starting with 0.01 |g/kg/min effect-adjusted, dopamine infusion (3-7 |g/kg/min), prednisolone 500-1,000 mg i.v., and vasopressors (Caffedrine/ theoadrenalin, etilefrine, or norepinephrine).

Degree 4 is a failure of vital organs resulting in car-diorespiratory arrest. Immediate basic and advanced life support must be initiated. In addition to the measures taken in degree 3 anaphylaxis, fluid resuscitation exceeding the amount of 2,000-3,000 ml and norepinephrine in boluses of 10-50 |g i.v. must be given (Heck and Fresenius 2004).

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