A 19-year old, 115 kg man sustained multiple unilateral rib fractures in an automobile accident two hours ago. Abdominal paracentesis is positive for blood, and an emergency laparotomy is planned urgently. The patient admits to heavy beer consumption before the accident. He appears pale, clammy, and dysgenic. Blood pressure is 95/70 mmHg, pulse is 120 bpm, and hematocrit is 26.
1. Is this patient in shock?
2. What are possible causes of shock in this patient?
3. What is the basis of the narrow pulse pressure?
4. What is appropriate therapy now?
5. How do you decide when he is ready for surgery?
II. Chest injury
1. How do you assess his respiratory status?
2. What do his fractured ribs mean to his anesthetic care?
3. What are potential related injuries?
4. Is preoperative chest tube placement necessary? Why or why not?
5. Is an electrocardiogram indicated? Why or why not?
1. What is the significance of his hematocrit to you?
A lowered hematocrit indicates acute blood loss, and this causes reduced viscosity and improved tissue blood flow, but a decreased oxygen-carrying capacity.
2. Is blood transfusion indicated prior to induction of anesthesia? Why or why not?
The optimal hematocrit to maintain tissue oxygen delivery is about 30%. In light of active bleeding, the induction of general anesthesia with associated decreases in systemic vascular resistance and cardiac output, the cardiac depression associated with acute alcohol intoxication, and the likelihood of significant blood loss for this case, blood transfusion prior to induction of anesthesia would be most appropriate.
3. What are the major systems affected by acute alcoholic intoxication?
Patients with acute alcohol intoxication are considered to be "full stomachs". They may be dehydrated, hypothermic, vasodilated, and therefore susceptible to hypotension. They have a decreased MAC, and this results in synergistic cardiac and respiratory depression when combined with other depressants. One may find metabolic conditions like hypoglycemia, alcoholic ketoacidosis. Also, these patients are often chronic alcoholics; therefore major systems may have altered physiology as well.
3. What are the major systems affected by chronic alcohol consumption?
Chronic alcoholism can lead to increased requirements for volatile anesthetics and intravenous induction drugs. Withdrawal can lead to delirium tremens or seizures. Other findings include peripheral neuropathy, hypertension, alcoholic cardiomyopathy and its associated symptoms of congestive heart failure and dysrrhythmias, gastrointestinal bleeding, esophageal varices, hepatitis, pancreatitis, induction of hepatic enzymes and increased requirement for sedatives, analgesics, and neuromuscular blockers. Thiamin, folate and vitamin B12 deficiency may exist, as well as hypomagnesemia, hypophosphatemia, and hypocalcemia, anemia, thrombocytopenia, and coagulation dysfunction.
4. What are some stigmata of liver disease?
Spider angiomata, palmar erythema, jaundice, ascites, gynecomastia, enlarged parotids and lacrimals, and abnormal coagulation are stigmata of liver disease.
5. What are signs of early alcoholic withdrawal?
Tachycardia, restlessness, agitation, tremor, and confusion.
6. What are minimum preoperative laboratory tests for alcoholic patients?
An alcoholic patient should have a preoperative complete blood count, platelet count, electrolytes, blood urea nitrogen, creatinine, glucose, liver enzymes, albumin, bilirubin, coagulation tests, calcium, magnesium, phosphorus, and a preoperative electrocardiogram.
3. What are some compensatory changes seen with acute blood loss?
Increased cardiac output occurs secondary to decreased blood viscosity, increased venous tone, and increased sympathetic response. There is also redistribution of blood flow to vital organs like the heart and brain, and an increase in oxygen extraction.
1. Is a central venous catheter indicated preoperatively? Explain.
2. Is an arterial line indicated preoperatively? Explain.
3. Can arterial waveforms assist you in intraoperative patient management?
4. What is the value of pulse oximetry and end-tidal CO2 in this patient?
Selection of anesthesia, induction and intubation
1. What are your major concerns prior to induction?
2. A colleague suggests awake intubation in view of obesity and a full stomach. Do you agree?
3. What problems are associated with obesity?
Cardiovascular disease, diabetes, and hypertension are more frequent in obese patients, who are over twenty percent of their body weight. They are prone to have difficulty with assisted mask ventilation, and with intubation. They desaturate easily, due to decreased functional residual capacity, ventilation/perfusion mismatch, pickwickian syndrome and associated sleep apnea, pulmonary hypertension, and possible right ventricular failure. They have a higher incidence of hiatal hernia and reflux esophagitis, a higher gastric volume, and a more acidic pH. They have altered pharmacokinetics. Also, regional anesthesia is frequently unsuccessful in these patients.
3. The patient struggles with attempted awake intubation. Will you use a priming dose of relaxant? Why or why not?
4. Give your choice of agents for rapid sequence induction and explain your choices.
1. What is the effect of acute alcohol intake on anesthetic requirements and toxicity?
2. What is the effect of chronic alcohol intake on anesthetic requirements and toxicity?
3. Is inhalation anesthetic contraindicated?
4. Explain the effect of obesity on the choice of maintenance agents.
1. Thirty-minutes after start of surgery, severe hypotension develops acutely. What is your differential diagnosis?
2. The central venous pressure is 25 mm Hg, neck veins are distended, and peak inspiratory pressure is normal and unchanged. What is your differential diagnosis?
3. What is your treatment?
Transfusion of blood products
1. Rapid blood loss occurs during splenectomy. Are packed red blood cells your first transfusion choice? Explain.
2. You choose not to transfuse packed red blood cells. Explain an alternate choice.
3. Is Lactated Ringer's solution appropriate as a diluent for packed red blood cells? Explain.
4. When is fresh frozen plasma indicated?
5. When are platelets indicated?
6. How do platelets cause coagulation?
They have a phospholipid, platelet factor 3, which limits coagulation to the site of platelet aggregation. They release granules containing thromboxane A2, which constricts vessels and increases adenosine diphosphate also, which further aggregates and activates platelets.
6. Red urine is noted after the third unit of blood is transfused. What is your differential diagnosis?
7. What are your major concerns?
8. What is your management strategy?
9. How would you manage further blood volume replacement?
I. Ventilatory support and extubation
1. Is there an absolute need for mechanical ventilation postoperatively? Explain.
2. What are your criteria for extubation of this patient?
3. Why is vital capacity measured?
Management of hypothermia
1. The patient arrives in the recovery room intubated with a rectal temperature of 32 degrees centigrade. What are your concerns?
2. What is the effect of hypothermia on recovery?
3. What is the effect of hypothermia on reversal of muscle relaxants?
4. What are the consequences of shivering?
1. Presume several hours of postoperative ventilatory support. A colleague suggests thoracic epidural narcotics via catheter. Do you agree or disagree? Explain.