53.4 Septic shock

Although septic shock might be considered out of place in a system of traumatology, it is more conveniently discussed with other kinds of shock, than with the surgery of sepsis. This is the draining of pus from the many sites in which it can collect, and is described in Chapters 5 to 8 of Volume One.

Septic shock is a common cause of surgical death. Once it has developed, a patient has a 50% chance of death, even in a good unit. His outlook is better if he is young and his history is short. It is the result of the release of endotoxins from lysed bacteria, especially Gram negative bacilli, into his circulation. It is not the same as septicaemia caused by intact living bacteria. Provided the bacteria remain intact, a patient can be septicaemic without being shocked.

Septic shock usually starts suddenly. The drop in a patient’s blood pressure may be castastrophic. He may be disoriented, confused, delirious, or comatose. He breathes rapidly. His blood pressure is low. He is always febrile, and his pulse is fast. A characteristic sign is a high rectal (or vaginal) temperature and cold extremities. A patient in septic shock is acidotic and breathes deeply and rapidly. He may have diarrhoea and ileus simultaneously. He is usually jaundiced, is often anaemic, and passes little or no urine (a bad sign). He may develop DIC (disseminated intravascular coagulation), and bleed from a wound, from his nose, or his gut, or into his urine. His heart, lungs and kidneys may fail, causing pulmonary oedema and oliguria.

There are two kinds—‘warm’ and ‘cold’; the cold may follow the warm: (1) In the less common, less lethal warm kind, typically caused by Gram positive cocci, the patient has warm, pink (if he is Caucasian) extremities, a large pulse pressure and a bounding pulse. (2) In the more common and even more dangerous cold kind, usually caused by Gram negative bacilli, he has cold and clammy extremities.

Suspect that a patient is in septic shock if he is already infected and suddenly becomes severely ill and hypotensive. The source of his infection can be peritonitis (6.2), septic abortion (16.3), infected bums (58.23), the transfusion of infected blood, pyaemia, or the instrumentation of an infected bladder (22.8). Or, his infection may be hidden, and make diagnosis difficult.

Treatment is urgent. The first consideration is to give him fluids, and to adjust the volumes you give to his urine output. Measuring his CVP is not useful, even if you can measure it, because he can develop pulmonary oedema when it is in the normal range.

SEPTIC SHOCK

Take blood cultures, and culture pus from any septic lesion.

OXYGEN Give the patient oxygen through a mask.

NURSING Tepid sponging will comfort him. Don’t let him develop hyperpyrexia.

ANTIBIOTICS Give him large doses of not less than three bactericidal antibiotics, if possible intravenously, as a bolus injection. Choices include: (1) Benzyl penicillin 5–10 megaunits 4-hourly with chloramphenicol 1 g 6-hourly, or streptomycin 500 mg 6-hourly. (2) Gentamicin 2 to 5 mg/kg daily by intramuscular or slow intravenous injection in divided doses every 8 hours. In renal failure increase the interval between the doses. (3) Methicillin 1 g by intramuscular or slow intravenous injection 4 to 6 hourly. (4) Kanamycin 15–30 mg/kg daily by slow intravenous injection in divided doses every 8–12 hours. (5) Cephaloridine 0.5–1 g every 8–12 hours by intramuscular or slow intravenous injection. The maximum dose is 6 g daily, or 4 g in patients over 50 or within 2 days of surgery. Give children 20 to 40 mg/kg daily in divided doses, to a maximum of 4 g. (3) Metronidazole for anaerobes. By mouth 400 mg 8-hourly. By rectum 1 g 8-hourly for 3 days then 1 g 12-hourly. Intravenously give 500 mg 8 hourly up to 7 days. Give a child 7.5 mg/kg 8-hourly by any route.

WHICH INTRAVENOUS FLUID?

Be guided by his serum electrolytes. If you cannot measure these, give him 0.9% saline, 5% dextrose in 0.9% saline, Ringer’s lactate, or Darrrow’s solution. Hyponatraemia is common, so 5% dextrose alone is unsafe. He would probably also benefit from a colloid such as dextran.

HOW MUCH FLUID?

He may need as much as 50 ml/kg/24hrs in addition to his normal daily water requirements in Fig. 58.6. An adult may need 6 litres in 24 hours. Be guided by his hourly urine output. Aim for a urine output of at least 30 ml/hr.

If he develops pulmonary oedema, give him frusemide 100–200 mg two or three times daily. If possible, watch his sodium and especially his potassium level and correct them

If he develops into acute left ventricular failure, give him digoxin 0.5 mg, repeated as necessary. If an electrocardiogram is available, use it as a guide to therapy. If not, count his pulse and apex beat together. If he has a pulse deficit, you are over digitalizing him.

OTHER DRUGS

After you have given him adequate fluids, consider giving him the following drugs, they are not so important as giving him adequate fluids.

Dopamine which will increase his cardiac output and tissue perfusion. Give him 1 to 4 micrograms/kg/min. To give this dissolve 4 mg in 500 ml of fluid.

Chlorpromazine which may relieve his peripheral vasoconstriction. If his extremities are cold and clammy give him chlorpromazine 0.5 mg/kg.

Steroids are of doubtful value. Give him dexamethazone 50 mg (or its equivalent) intravenously, and repeat this every 4–6 hours.

DRAIN PUS

if you can drain the septic focus, do so. Timing is important: he must be fit enough to stand the procedure, so overcome shock first. Do the simplest possible operation. This will need courage because he will be very ill, and he may not survive it. It may however save his life. You may need to evacuate a septic abortion, drain a pelvic or subphrenic abscess, or re-explore his abdomen.