ABSITE Review Conference: Surgical Infection Neurosurgery Surgical Infection The vagus nerve mediates which of the following in the setting of systemic inflammation? (A) Enhanced gut motility (B) Decreased protein production by the liver (C) Decreased IL-10 production (D) Increased heart rate to increase cardiac output Surgical Infection The vagus nerve mediates which of the following in the setting of systemic inflammation? (A) Enhanced gut motility (B) Decreased protein production by the liver (C) Decreased IL-10 production (D) Increased heart rate to increase cardiac output Surgical Infection Explanation: The vagus nerve exerts several homeostatic influences, including enhancing gut motility, reducing heart rate, and regulating inflammation. Central to this pathway is the understanding of neurally controlled anti-inflammatory pathways of the vagus nerve. Parasympathetic nervous system activity transmits vagus nerve efferent signals primarily through the neurotransmitter acetylcholine. This neurally mediated anti-inflammatory pathway allows for a rapid response to inflammatory stimuli and also for the potential regulation of early proinflammatory mediator release, specifically tumor necrosis factor (TNF). Vagus nerve activity in the presence of systemic inflammation may inhibit cytokine activity and reduce injury from disease processes such as pancreatitis, ischemia and reperfusion, and hemorrhagic shock. This activity is primarily mediated through nicotinic acetylcholine receptors on immune mediator cells such as tissue macrophages. Furthermore, enhanced inflammatory profiles are observed after vagotomy, during stress conditions. Surgical Infection Cytokines are which type of hormone? (A) Polypeptide (B) Amino acid (C) Fatty acid (D) Carbohydrate Surgical Infection Cytokines are which type of hormone? (A) Polypeptide (B) Amino acid (C) Fatty acid (D) Carbohydrate Surgical Infection Explanation: Cytokines are polypeptide hormones. Humans release hormones in several chemical categories, including polypeptides (e.g., cytokines, glucagon, and insulin), amino acids (e.g., epinephrine, serotonin, and histamine), and fatty acids (e.g., glucocorticoids, prostaglandins, and leukotrienes). There are no carbohydrate hormones. Surgical Infection The primary source of calories during acute starvation (<5 days fasting) is (A) Fat (B) Muscle (protein) (C) Glycogen (D) Ketone bodies Surgical Infection The primary source of calories during acute starvation (<5 days fasting) is (A) Fat (B) Muscle (protein) (C) Glycogen (D) Ketone bodies Surgical Infection Explanation: In the healthy adult, principal sources of fuel during short-term fasting (<5 days) are derived from muscle protein and body fat, with fat being the most abundant source of energy. Surgical Infection Which of the following is the primary fuel source in prolonged starvation? (A) Fat (B) Muscle (protein) (C) Glycogen (D) Ketone bodies Surgical Infection Which of the following is the primary fuel source in prolonged starvation? (A) Fat (B) Muscle (protein) (C) Glycogen (D) Ketone bodies Surgical Infection Explanation: In prolonged starvation, systemic proteolysis is reduced to approximately 20 g/d and urinary nitrogen excretion stabilizes at 2 to 5 g/d (Fig. 2-3). This reduction in proteolysis reflects the adaptation by vital organs (e.g., myocardium, brain, renal cortex, and skeletal muscle) to using ketone bodies as their principal fuel source. In extended fasting, ketone bodies become an important fuel source for the brain after 2 days and gradually become the principal fuel source by 24 days. Surgical Infection How many calories per day are required to maintain basal metabolism in a healthy adult? (A) 10-15 kcal/kg/day (B) 20-25 kcal/kg/day (C) 30-35 kcal/kg/day (D) 40-45 kcal/kg/day Surgical Infection How many calories per day are required to maintain basal metabolism in a healthy adult? (A) 10-15 kcal/kg/day (B) 20-25 kcal/kg/day (C) 30-35 kcal/kg/day (D) 40-45 kcal/kg/day Surgical Infection Explanation: To maintain basal metabolic needs (i.e., at rest and fasting), a normal healthy adult requires approximately 22 to 25 kcal/kg per day drawn from carbohydrate, lipid, and protein sources. Surgical Infection A patient presents to the emergency room with a temperature of 39°C, a heart rate of 115, and a respiratory rate of 25. There are no localizing symptoms and the work-up does not reveal any specific source for the fever. Which of the following best describes this patient's condition? (A) Infection (B) SIRS (C) Sepsis (D) Septic shock Surgical Infection A patient presents to the emergency room with a temperature of 39°C, a heart rate of 115, and a respiratory rate of 25. There are no localizing symptoms and the work-up does not reveal any specific source for the fever. Which of the following best describes this patient's condition? (A) Infection (B) SIRS (C) Sepsis (D) Septic shock Surgical Infection Explanation: This patient meets the criteria for SIRS. Because there is no identifiable source for the condition, the criteria for infection and sepsis have not been met. Septic shock is sepsis with cardiovascular collapse Surgical Infection Cortisol is elevated in response to severe injury. How long can this response persist in a patient with a significant burn? (A) 2 days (B) 1 week (C) 1 month (D) 3 months Surgical Infection Cortisol is elevated in response to severe injury. How long can this response persist in a patient with a significant burn? (A) 2 days (B) 1 week (C) 1 month (D) 3 months Surgical Infection Explanation: Cortisol is a glucocorticoid steroid hormone released by the adrenal cortex in response to ACTH. Cortisol release is increased during times of stress and may be chronically elevated in certain disease processes. For example, burn-injured patients may exhibit elevated levels for 4 weeks. Surgical Infection Overfeeding (RQ >1.0) in a critically ill patient can result in (A) Pancreatitis (B) Increased risk of infection (C) Atelectasis (D) Increased risk of DVT Surgical Infection Overfeeding (RQ >1.0) in a critically ill patient can result in (A) Pancreatitis (B) Increased risk of infection (C) Atelectasis (D) Increased risk of DVT Surgical Infection Explanation: Excess glucose from overfeeding, as reflected by RQs >1.0, can result in conditions such as glucosuria, thermogenesis, and conversion to fat (lipogenesis). Excessive glucose administration results in elevated carbon dioxide production, which may be deleterious in patients with suboptimal pulmonary function, as well as hyperglycemia, which may contribute to infectious risk and immune suppression. Overfeeding may contribute to clinical deterioration via increased oxygen consumption, increased carbon dioxide production and prolonged need for ventilatory support, fatty liver, suppression of leukocyte function, hyperglycemia, and increased risk of infection. Surgical Infection Which is the most commonly cultured hospital acquired organism in critical care patients with aspiration pneumonia? (A) Streptococcus pneumoniae (B) Staphylococcus aureus (C) anaerobic species (D) Pseudomonas aeruginosa (E) Haemophilus influenzae Surgical Infection Which is the most commonly cultured hospital acquired organism in critical care patients with aspiration pneumonia? (A) Streptococcus pneumoniae (B) Staphylococcus aureus (C) anaerobic species (D) Pseudomonas aeruginosa (E) Haemophilus influenzae Surgical Infection When should parenteral antibiotics be given perioperatively? (A) the night before (B) 6 h prior to surgery (C) 30 min prior to incision (D) at the time of incision (E) 30 min after incision Surgical Infection When should parenteral antibiotics be given perioperatively? (A) the night before (B) 6 h prior to surgery (C) 30 min prior to incision (D) at the time of incision (E) 30 min after incision Surgical Infection Explanation: Wound infections or surgical site infections (SSI) are markedly reduced with preoperative antibiotic administration as noted above. Wound infections are classified as superficial or deep incisional SSIs. One-third of postoperative infections are organ/space SSIs. Infection occurs within 30 days of operation (or 1 year if an implant is left) and involves either the skin and subcutaneous tissue or fascia and muscle layers, respectively. Either pus, evidence of cellulitis, fever, opening of wound, positive cultures or evidence of abscess, or diagnosis by surgeon or attending physician must be noted. Bacterial killing by neutrophils is reduced by approximately 25% and may take as long as 10 days to recover after surgery. Use of preoperative antibiotics as prophylaxis reduces the risk of wound infection, endocarditis, or prosthetic material infection. It has no role in preventing most other types of nosocomial infections. Surgical Infection Wounds can be classified as clean, clean-contaminated, contaminated, or dirty. The risk of infection is 1.5, 7.5, 15, and 40%, respectively. Class I or clean wounds are those that are atraumatic or operative incisions with associated blunt trauma, without associated inflammation. The respiratory, alimentary, genital, uninfected urinary tract, or biliary tracts are not entered. These are closed primarily with or without closed drainage systems. An example is a hernia operation. Class II or clean-contaminated enter the above tracts under controlled conditions and without unusual contamination. Examples include nonruptured appendix, vaginal hysterectomy, and cholecystectomy. Class III or contaminated cases include traumatic wounds, major breaks in sterile techniques, gross spillage from the gastrointestinal tract, and incisions where acute, nonpurulent inflammation is encountered. Open cardiac massage is an example. Class IV or dirty wounds involve old traumatic wounds with retained devitalized tissue and those that involve existing clinical infection or perforated viscera. An example is a Hartmann's operation for perforated diverticulitis. Surgical Infection Timing of the first dose is critical in relation to skin incision. Administration is ideally complete, or at least under way, when the patient enters the operating theatre to achieve appropriate tissue levels. Intravenous antibiotics should be administered 30 min before the operative incision. Antibiotics should be dosed every 4 h. Further maneuvers such as preoperative bathing with disinfectants, proper skin preparation, careful placement of drapes, protection of the wound edges from contaminated fluids and viscera, and careful surgical technique all help reduce the risk of SSIs. Razor shaving of the skin on the evening before surgery increases wound infections. If hair must be removed, the following techniques should be used in order of preference: depilatory creams, hair clipping immediately before prepping, and finally shaving immediately before prepping. Postoperative wound management includes protecting the wound with a sterile dressing for 24–48 h postoperatively (category IB—recommendations are supported by some experimental, clinical, or epidemiologic studies and strong theoretical rationale). Surgical Infection Length of prophylaxis is controversial; many times no or only one postoperative dose is necessary. The goal of antibiotic prophylaxis is to maintain the operative levels of antibiotics during operative exposure of the tissue and for a short period thereafter. The indication for antibiotic prophylaxis is based on the surgeon's preoperative prediction of how the wound will be classified at the end of the operation. Prophylaxis beyond 24 h is not supported. Surgical Infection The pathogen most commonly responsible for the onset of septic shock is (A) Klebsiella (B) Pseudomonas (C) Staphylococcus (D) Escherichia coli (E) Bacteroides Surgical Infection The pathogen most commonly responsible for the onset of septic shock is (A) Klebsiella (B) Pseudomonas (C) Staphylococcus (D) Escherichia coli (E) Bacteroides Surgical Infection Explanation: Sepsis and septic shock have become especially prominent in this age of high tech intervention in high-risk patients. This condition afflicts approximately 750,000 individuals and accounts for a mortality of 30–60%. Sepsis represents an unrestrained inflammatory process, arising in the setting of the SIRS. As defined by a consensus conference in 1991, SIRS is a generalized inflammatory process associated with a variety of etiologies, including pancreatitis, multiple trauma, hemorrhagic shock, and vascular occlusion (Fig. 6-18). Among the criteria for SIRS are a body temperature >38 or <36°C; a heart rate >90 bpm; a respiratory rate >20 or a PaCO2 <32 mmHg; a white blood cell count >12,000 or <4000; and a bandemia >10%. Two of these criteria must be met to fulfill a diagnosis of SIRS. In the presence of a documented infection, SIRS becomes sepsis. Surgical Infection Explanation: The most common pathogen associated with the bacteremia of sepsis and septic shock is the gram-negative bacilli, most notably E. coli; however, other gram-negative bacterial species— Klebsiella, Proteus, and Pseudomonas—as well as the gram-positive bacteria are often isolated from the blood cultures of septic patients. A fungemia or viremia also may give rise to sepsis. Positive blood cultures are obtained in 45% of septic patients. The majority of these infections emanate from the genitourinary, gastrointestinal, and biliary tracts and the tracheobronchial tree. Surgical Infection A 46-year-old female develops septic shock following an open cholecystectomy for a gangrenous gallbladder. She remains intubated after surgery but exhibits persistent hypoxia with maximal ventilator support. The diagnosis of acute respiratory distress syndrome (ARDS) is suggested. Positive end-expiratory pressure (PEEP) is added to this patient's ventilatory support with an improvement in her oxygenation. The mechanism by which PEEP functions includes (A) reduction in the rate of pulmonary edema formation (B) improvement in the reabsorption of edema fluid (C) promotion of the opening of collapsed alveoli (D) prevention of the collapse of alveoli (E) enhancement of surfactant production Surgical Infection A 46-year-old female develops septic shock following an open cholecystectomy for a gangrenous gallbladder. She remains intubated after surgery but exhibits persistent hypoxia with maximal ventilator support. The diagnosis of acute respiratory distress syndrome (ARDS) is suggested. Positive end-expiratory pressure (PEEP) is added to this patient's ventilatory support with an improvement in her oxygenation. The mechanism by which PEEP functions includes (A) reduction in the rate of pulmonary edema formation (B) improvement in the reabsorption of edema fluid (C) promotion of the opening of collapsed alveoli (D) prevention of the collapse of alveoli (E) enhancement of surfactant production Surgical Infection Explanation: Treatment of ARDS rests on the support of pulmonary function while limiting additional lung injury. A majority of patients with ARDS require mechanical ventilation, with the goal of keeping the PaO2 greater than 60 mmHg or the oxygen saturation higher than 90%. The ventilation-perfusion mismatch may prevent an increase in PaO2 despite the administration of supplemental oxygen; however, a FiO2 of less than 50% is recommended to avoid further lung injury from oxygen toxicity. The application of PEEP is essential in maximizing oxygen exchange and, thus, PaO2. Alveoli are predisposed to collapse at end expiration because of low lung volumes, pulmonary edema, and the deficiency of surfactant. The application of PEEP prevents this collapse, making more alveoli available for gas exchange. Additionally, studies have suggested that PEEP may redirect pulmonary artery circulation to better ventilated areas of the lung, lessening the ventilation-perfusion mismatch. Yet, PEEP may contribute to lung injury by inducing barotrauma through alveolar overdistention. Also, cardiac output may be compromised by the addition of PEEP; consequently, the systemic delivery of oxygen is reduced. Other strategies for the management of ARDS include inverse ratio ventilation, high-frequency jet ventilation, and prone positioning. In one study, corticosteroids improved survival in patients with ARDS: the use of steroids was associated with a mortality of 38%, significantly less than the 67% mortality in the nonsteroid group. The utility of corticosteroids in treating ARDS, however, remains a point of contention. Surgical Infection A 42-year-old White female comes to the ER complaining of RUQ pain for the last 36 h, associated with fever up to 39°C, bilious emesis, and jaundice. Direct bilirubin 2.2, alkaline phosphatase 450, WBC 19,000, AST 24, ALT 19. The most probable diagnosis is acute cholangitis. What would be the most appropriate antibiotic therapy for this patient? (A) cloxcicillin + tobramycin (B) piperacillin/tazobactam (C) Cefazolin (D) ampicillin + clindamicin (E) metronidazol + ciprofloxacin Surgical Infection A 42-year-old White female comes to the ER complaining of RUQ pain for the last 36 h, associated with fever up to 39°C, bilious emesis, and jaundice. Direct bilirubin 2.2, alkaline phosphatase 450, WBC 19,000, AST 24, ALT 19. The most probable diagnosis is acute cholangitis. What would be the most appropriate antibiotic therapy for this patient? (A) cloxcicillin + tobramycin (B) piperacillin/tazobactam (C) Cefazolin (D) ampicillin + clindamicin (E) metronidazol + ciprofloxacin Surgical Infection Explanation: Acute cholangitis is an inflammation/infection process that develops as a result of bacterial colonization and overgrowth within an obstructed biliary system. The obstruction and cholangitis result from impacted stones in 80% of the cases in the Western world. Such stones most commonly originate from the gallbladder (secondary to CBD stones). Primary stones, most commonly pigmented are seen in the East Asian countries. Other causes are benign strictures, neoplasms, papillary stenosis, sclerosing cholangitis, foreign bodies and so on. Surgical Infection Explanation: Fifty to seventy percent of the patients will present with the Charcot's triad (abdominal pain, fever, and jaundice). The combination of confusion, hypotension, and the Charcot's triad constitutes the Reynold's pentad, which is invariably fatal if urgent biliary decompression is not done. Chronic biliary obstruction may lead to liver abscesses and secondary biliary cirrhosis. Organ failure and sepsis, sclerosing cholangitis and strictures may develop. Spread of the infection into the portal vein can cause pyelophlebitis and portal vein thrombosis. Analysis of the bile and blood in prospective studies showed that E. coli (27–70%), Klebsiella spp. (17–14%), Enterobacter spp. (5–8%), and Enteroccocus spp. (17%) were the most common isolated organisms. C. albicans is the most common fungal cause in immunocompromised patients. Surgical Infection Explanation: A combination of abdominal US, CT scan, and cholangiography complements and confirm the clinical diagnosis of cholangitis. Direct cholangiography (ERCP, PTC) is the gold standard for diagnosing acute cholangitis. ERCP is less invasive and has the advantage that offers therapeutic measures, including stone extraction and biliary drainage. PTC is used when ERCP failed or in patients with previous biloenteric anastamosis. The management begins with early recognition and aggressive antibiotic coverage. Approximately 80% of the patients will improve with conservative therapy. The 20% remaining will require biliary drainage. Therapeutic endoscopy is the method of choice for biliary decompression, when it is not available or unsuccessful. Percutaneous transhepatic biliary decompression or surgery should be contemplated. High morbidity and mortality of immediate surgical decompression leaves this option as a last resource. Once the acute event has resolved, a detailed treatment plan can be carried out electively to remove the underlying obstruction. Surgical Infection Asplenic individuals are at increased risk for severe fatal infections from all of the following except: (A) S. pneumoniae (B) N. meningitidis (C) H. influenzae (D) E. coli (E) Candida albicans Surgical Infection Asplenic individuals are at increased risk for severe fatal infections from all of the following except: (A) S. pneumoniae (B) N. meningitidis (C) H. influenzae (D) E. coli (E) Candida albicans Surgical Infection Explanation: The spleen plays an important role in defense against a wide range of microorganisms and its activities are mediated through multiple peculiarities unique to its anatomy. The immunologic functions of the spleen cannot be fully duplicated following its removal so that patients become vulnerable to severe, fulminant, life-threatening infection after splenectomy, most notoriously because of encapsulated bacteria. This may be manifested through pneumonia or meningitis; however, in many cases a focus of infection cannot be identified even in the presence of high-grade bacteremia. The greatest risk is posed by encapsulated bacteria such as S. pneumoniae (Pneumococcus), N. meningitides (Meningococcus), and H. influenzae, although a multitude of other organisms have been implicated, including gram-negative rods such as E. coli, Klebsiella, Enterobacter, Proteus, Pseudomonas, Serratia, and Salmonella species; Enterococcus; and Staphylococcus and Clostridium species. Surgical Infection The antibiotic of choice in a penicillin allergic patient undergoing a cholecystectomy for acute cholecystitis is (A) Ertepenem (B) Ceftriaxone (C) Vancomycin + Metronidazole (D) Fluoroquinolone + Metronidazole Surgical Infection The antibiotic of choice in a penicillin allergic patient undergoing a cholecystectomy for acute cholecystitis is (A) Ertepenem (B) Ceftriaxone (C) Vancomycin + Metronidazole (D) Fluoroquinolone + Metronidazole Surgical Infection Explanation: Fluoroquinolone plus either metronidazole or clindamycin (for anaerobic coverage) is indicated in penicillin allergic patients undergoing biliary tract surgery with active infection. Surgical Infection Which of the following is the most effective dosing of antibiotics in a patient undergoing elective colon resection? (A) A single dose given within 30 min prior to skin incision (B) A single dose given at the time of skin incision (C) A single preoperative dose + 24 hours of postoperative antibiotics (D) A single preoperative dose + 48 hours of postoperative antibiotics Surgical Infection Which of the following is the most effective dosing of antibiotics in a patient undergoing elective colon resection? (A) A single dose given within 30 min prior to skin incision (B) A single dose given at the time of skin incision (C) A single preoperative dose + 24 hours of postoperative antibiotics (D) A single preoperative dose + 48 hours of postoperative antibiotics Surgical Infection Explanation: By definition, prophylaxis is limited to the time before and during the operative procedure; in the vast majority of cases only a single dose of antibiotic is required, and only for certain types of procedures. However, patients who undergo complex, prolonged procedures in which the duration of the operation exceeds the serum drug half-life should receive an additional dose or doses of the antimicrobial agent. Nota bene: There is no evidence that administration of postoperative doses of an antimicrobial agent provides additional benefit, and this practice should be discouraged, as it is costly and is associated with increased rates of microbial drug resistance. Surgical Infection Appropriate duration of antibiotic therapy for most patients with bacterial peritonitis from perforated appendicitis is (A) 3-5 days (B) 7-10 days (C) 14-21 days (D) >21 days Surgical Infection Appropriate duration of antibiotic therapy for most patients with bacterial peritonitis from perforated appendicitis is (A) 3-5 days (B) 7-10 days (C) 14-21 days (D) >21 days Surgical Infection Explanation: The majority of studies examining the optimal duration of antibiotic therapy for the treatment of polymicrobial infection have focused on patients who develop peritonitis. Cogent data exist to support the contention that satisfactory outcomes are achieved with 12 to 24 hours of therapy for penetrating GI trauma in the absence of extensive contamination, 3 to 5 days of therapy for perforated or gangrenous appendicitis, 5 to 7 days of therapy for treatment of peritoneal soilage due to a perforated viscus with moderate degrees of contamination, and 7 to 14 days of therapy to adjunctively treat extensive peritoneal soilage (e.g., feculent peritonitis) or that occurring in the immunosuppressed host. In the later phases of postoperative antibiotic treatment of serious intraabdominal infection, the absence of an elevated WBC count, lack of band forms of PMNs on peripheral smear, and lack of fever [<38.6°C (100.5°F)] provide close to complete assurance that infection has been eradicated. Under these circumstances, antibiotics can be discontinued with impunity. Surgical Infection Which of the following can be used to mitigate cortisol effects on wound healing? (A) Vitamin A (B) Vitamin B1 (C) Vitamin C (D) Vitamin E Surgical Infection Which of the following can be used to mitigate cortisol effects on wound healing? (A) Vitamin A (B) Vitamin B1 (C) Vitamin C (D) Vitamin E Surgical Infection Explanation: Wound healing also is impaired, because cortisol reduces transforming growth factor beta (TGF-) and insulin-like growth factor I (IGF-I) in the wound. This effect can be partially ameliorated by the administration of vitamin A. Surgical Infection The most common cause of hepatic abscess in the United States is (A) GI infection with entoameoba histolytica (B) Pylephlebitis from appendicitis (C) Biliary tract procedures (D) Primary bacterial infection after septicemia Surgical Infection The most common cause of hepatic abscess in the United States is (A) GI infection with entoameoba histolytica (B) Pylephlebitis from appendicitis (C) Biliary tract procedures (D) Primary bacterial infection after septicemia Surgical Infection Explanation: Hepatic abscesses are rare, currently accounting for approximately 15 per 100,000 hospital admissions in the United States. Pyogenic abscesses account for approximately 80% of cases, the remaining 20% being equally divided among parasitic and fungal forms. Formerly, pyogenic liver abscesses were caused by pylephlebitis due to neglected appendicitis or diverticulitis. Today, manipulation of the biliary tract to treat a variety of diseases has become a more common cause, although in nearly 50% of patients no cause is identified. Surgical Infection Which of the following best estimates the risk of a surgical site infection (SSI) in a patient undergoing an elective low anterior colon resection? (A) 1-5% (B) 2-10% (C) 10-25% (D) >25% Surgical Infection Which of the following best estimates the risk of a surgical site infection (SSI) in a patient undergoing an elective low anterior colon resection? (A) 1-5% (B) 2-10% (C) 10-25% (D) >25% Surgical Infection Explanation: The expected infection rate in colorectal surgery (clean/contaminated) is 9.4 to 25%. Clean/contaminated wounds (class II) include those in which a hollow viscus such as the respiratory, alimentary, or genitourinary tracts with indigenous bacterial flora is opened under controlled circumstances without significant spillage of contents. Interestingly, while elective colorectal cases have classically been included as class II cases, a number of studies in the last decade have documented higher SSI rates (9 to 25%). One study identified two thirds of infections presenting after discharge from hospital, highlighting the need for careful follow-up of these patients. Infection is also more common in cases involving entry into the rectal space. Surgical Infection Which of the following is most suggestive of a necrotizing soft tissue infection and would mandate immediate surgical exploration? (A) A small amount of grayish, cloudy fluid from a wound (B) Red, swollen extremity which is tender to palpation (C) Soft tissue infection with a fever >104° (D) Induration with pitting edema on the trunk Surgical Infection Which of the following is most suggestive of a necrotizing soft tissue infection and would mandate immediate surgical exploration? (A) A small amount of grayish, cloudy fluid from a wound (B) Red, swollen extremity which is tender to palpation (C) Soft tissue infection with a fever >104° (D) Induration with pitting edema on the trunk Surgical Infection Explanation: All of the above are suggestive of soft-tissue infection and may, in the appropriate clinical scenario, support surgical exploration. Since time from onset of symptoms to surgical debridement is one of the most critical factors in determination of outcome, the clinician should be willing to explore a potentially-affected area without a definitive diagnosis. Careful examination should be undertaken for an entry site such as a small break or sinus in the skin from which grayish, turbid semipurulent material ("dishwater pus") can be expressed, as well as for the presence of skin changes (bronze hue or brawny induration), blebs, or crepitus. The patient often develops pain at the site of infection that appears to be out of proportion to any of the physical manifestations. Any of these findings mandates immediate surgical intervention, which should consist of exposure and direct visualization of potentially infected tissue (including deep soft tissue, fascia, and underlying muscle) and radical resection of affected areas. Surgical Infection The appropriate duration of antibiotic therapy for nosocomial urinary tract infection is (A) 3-5 days (B) 7-10 days (C) 21 days (D) Until the patient is asymptomatic and the urinalysis is normal Surgical Infection The appropriate duration of antibiotic therapy for nosocomial urinary tract infection is (A) 3-5 days (B) 7-10 days (C) 21 days (D) Until the patient is asymptomatic and the urinalysis is normal Surgical Infection Explanation: The presence of a postoperative UTI should be considered based on urinalysis demonstrating WBCs or bacteria, a positive test for leukocyte esterase, or a combination of these elements. The diagnosis is established after more than 104 CFU/mL of microbes are identified by culture techniques in symptomatic patients, or more than 105 CFU/mL in asymptomatic individuals. Treatment for 3 to 5 days with a single antibiotic that achieves high levels in the urine is appropriate. Postoperative surgical patients should have indwelling urinary catheters removed as quickly as possible, typically within 1 to 2 days, as long as they are mobile. Surgical Infection A 42-year-old White female comes to the ER complaining of RUQ abdominal pain for the last 36 h, associated with fever up to 39°C, bilious emesis, and jaundice. Direct bilirubin 2.2, alkaline phosphatase 450, WBC 19,000, AST 24, ALT 19. The most probable diagnosis is acute cholangitis. What is the most appropriate treatment for this patient? (A) antibiotics and urgent surgical biliary decompression (B) antibiotics and endoscopic biliary decompression (C) antibiotics and percutaneous transhepatic biliary decompression (D) antibiotics, surgical decompression, and cholecystectomy Surgical Infection A 42-year-old White female comes to the ER complaining of RUQ abdominal pain for the last 36 h, associated with fever up to 39°C, bilious emesis, and jaundice. Direct bilirubin 2.2, alkaline phosphatase 450, WBC 19,000, AST 24, ALT 19. The most probable diagnosis is acute cholangitis. What is the most appropriate treatment for this patient? (A) antibiotics and urgent surgical biliary decompression (B) antibiotics and endoscopic biliary decompression (C) antibiotics and percutaneous transhepatic biliary decompression (D) antibiotics, surgical decompression, and cholecystectomy Surgical Infection Which of the following has been shown to decrease the rate of pancreatic abscess in patients with necrotizing pancreatitis? (A) Prophylactic antibiotics (B) Frequent imaging with percutaneous sampling of new fluid collections (C) Enteral nutrition (D) Parenteral nutrition Surgical Infection Which of the following has been shown to decrease the rate of pancreatic abscess in patients with necrotizing pancreatitis? (A) Prophylactic antibiotics (B) Frequent imaging with percutaneous sampling of new fluid collections (C) Enteral nutrition (D) Parenteral nutrition Surgical Infection Explanation: Current care of patients with severe acute pancreatitis includes staging with dynamic, contrast-enhanced helical CT scan with 3mm tomographs to determine the extent of pancreatic necrosis, coupled with the use of one of several prognostic scoring systems. Patients who exhibit significant pancreatic necrosis (grade greater than C, Fig. 6-2) should be carefully monitored in the ICU and undergo follow-up CT examination. A recent change in practice has been the elimination of the routine use of prophylactic antibiotics for prevention of infected pancreatic necrosis. Early results were promising; however, several randomized multicenter trials have failed to show benefit and three meta-analyses have confirmed this finding. In two small studies, enteral feedings initiated early, using nasojejunal feeding tubes placed past the ligament of Treitz, have been associated with decreased development of infected pancreatic necrosis, possibly due to a decrease in gut translocation of bacteria. Recent guidelines support the practice of enteral alimentation in these patients, with the addition of parenteral nutrition if nutritional goals cannot be met by tube feeding alone Surgical Infection Which structure is not affected by Fournier gangrene? (A) Genital (B) Perineal (C) Perianal (D) Periumbilical (E) none of the above Surgical Infection Which structure is not affected by Fournier gangrene? (A) Genital (B) Perineal (C) Perianal (D) Periumbilical (E) none of the above Surgical Infection Explanation: Fournier gangrene is polymicrobial necrotizing fascitis of the genital, perianal, or perineal areas. The skin may be erythematous, gangrenous, or malodorous, and air may be present on imaging studies. Escherichia coli (most common aerobe) and Bacteroides (most common anaerobe) usually cause it. Fournier gangrene is a urologic surgical emergency requiring aggressive debridement, hyperbaric oxygen, and intravenous antibiotics. Gas gangrene is caused by Clostridium perferingens and causes infection that spreads along muscle planes. Neurosurgery A 27-year-old man developed signs and symptoms of fulminant Cushing's syndrome over 3 months. He has central obesity, hypertension, and glucose intolerance. He is likely to have all of the following signs, which are fairly specific for Cushing's syndrome, except: (A) enlarged supraclavicular fat pads (B) purple stria (C) proximal neuropathy (D) ecchymosis Neurosurgery A 27-year-old man developed signs and symptoms of fulminant Cushing's syndrome over 3 months. He has central obesity, hypertension, and glucose intolerance. He is likely to have all of the following signs, which are fairly specific for Cushing's syndrome, except: (A) enlarged supraclavicular fat pads (B) purple stria (C) proximal neuropathy (D) ecchymosis Neurosurgery Explanation: Primary Cushing's syndrome occurs when there is excess secretion of cortisone by the adrenal glands. The symptoms usually begin insidiously, but occasionally the signs and symptoms can come on very rapidly. Women are more frequently involved than men. Most patients present in the third to the fifth decade of life, but the disorder can occur in childhood and adolescents. Central weight gain is the hallmark of the disorder and sometimes can be quite spectacular; however, some patients only gain a slight amount, but their body fat is redistributed around their abdomen. The skin is thin and stretched and purple stria and easy bruising are suggestive of the diagnosis. Neurosurgery Explanation: Many patients with Cushing's have proximal weakness in the legs, but the weakness is because of a proximal myopathy rather than a neuropathy. Hypertension and glucose intolerance are common. Other features of Cushing's may include a moon facies secondary to deposition of fat around the ears and cheeks, fat enlargement in the supraclavicular areas and posterior neck (buffalo hump), acne and facial hirsutism. Unfortunately there are no signs or symptoms of Cushing's syndrome to absolutely establish the diagnosis without a series of supportive laboratory tests. Neurosurgery All of the following are classic signs of a basal skull fracture except: (A) dilated and nonreactive pupil (B) bilateral periorbital ecchymosis (Raccoon's eyes) (C) ecchymosis over mastoids (Battle's sign) (D) hemotympanum Neurosurgery All of the following are classic signs of a basal skull fracture except: (A) dilated and nonreactive pupil (B) bilateral periorbital ecchymosis (Raccoon's eyes) (C) ecchymosis over mastoids (Battle's sign) (D) hemotympanum Neurosurgery • Explanation: Basal skull fractures are usually diagnosed by clinical signs. CT scan findings include linear lucencies through the skull base, pneumocephalus, and opacification of air sinuses. Clinical signs vary depending on the site of fracture. Anterior skull base fractures may cause anosmia, cerebrospinal fliud (CSF) rhinorrhea, and periorbital ecchymosis (raccoon's eyes). Middle fossa or temporal bone fractures may result in ecchymosis over the mastoids (Battle's sign, Fig. 9-6), hemotympanum, CSF otorrhea or rhinorrhea, and cranial nerve VII or VIII palsies. Neurosurgery • Explanation: A dilated and nonreactive pupil is often the result of compression of cranial nerve III causing interruption of the sympathetic fibers traveling along this nerve. This is most often a sign of elevated ICP and not of a basal skull fracture, although related trauma to the orbit could result in a dilated and nonreactive pupil. Other consequences of basal skull fractures include optic nerve injury, abducens nerve injury, traumatic carotid artery aneurysms, carotid-cavernous fistulae, CSF fistulae, meningitis, and cerebral abscess. Neurosurgery A patient with a crush injury to the arm has motor and sensory deficits that indicate a radial nerve injury. The most appropriate management is (A) Immediate operative exploration and repair (B) EMG 5-7 days after injury; surgical exploration if nerve conduction is decreased (C) EMG 3-4 weeks after injury; surgical exploration if nerve conduction is decreased (D) Surgical exploration if there is no functional improvement after 3 months Neurosurgery A patient with a crush injury to the arm has motor and sensory deficits that indicate a radial nerve injury. The most appropriate management is (A) Immediate operative exploration and repair (B) EMG 5-7 days after injury; surgical exploration if nerve conduction is decreased (C) EMG 3-4 weeks after injury; surgical exploration if nerve conduction is decreased (D) Surgical exploration if there is no functional improvement after 3 months Neurosurgery Explanation: The sensory and motor deficits [in a patient with a peripheral nerve injury] should be accurately documented. Deficits are usually immediate. Progressive deficit suggests a process such as an expanding hematoma and may warrant early surgical exploration. Clean, sharp injuries may also benefit from early exploration and reanastomosis. Most other peripheral nerve injuries should be observed. EMG/NCS studies should be done 3 to 4 weeks postinjury if deficits persist. Axon segments distal to the site of injury will conduct action potentials normally until Wallerian degeneration occurs, rendering EMG/NCS before 3 weeks uninformative. Continued observation is indicated if function improves. Neurosurgery Explanation: Surgical exploration of the nerve may be undertaken if no functional improvement occurs over 3 months. If intraoperative electrical testing reveals conduction across the injury, continue observation. In the absence of conduction, the injured segment should be resected and endto-end primary anastomosis attempted. However, anastomoses under tension will not heal. A nerve graft may be needed to bridge the gap between the proximal and distal nerve ends. The sural nerve often is harvested, as it carries only sensory fibers and leaves a minor deficit when resected. The connective tissue structures of the nerve graft may provide a pathway for effective axonal regrowth across the injury. Neurosurgery Unilateral loss of visual acuity and pulsatile proptosis is suggestive of (A) Retinal artery aneurysm (B) Carotid-cavernous fistula (C) Hypertensive crisis (D) Carotid artery dissection Neurosurgery Unilateral loss of visual acuity and pulsatile proptosis is suggestive of (A) Retinal artery aneurysm (B) Carotid-cavernous fistula (C) Hypertensive crisis (D) Carotid artery dissection Neurosurgery • Explanation: Traumatic vessel wall injury to the portion of the carotid artery running through the cavernous sinus may result in a carotid-cavernous fistula (CCF). This creates a high-pressure, high-flow pathophysiologic blood flow pattern. CCFs classically present with pulsatile proptosis (the globe pulses outward with arterial pulsation), retroorbital pain, and decreased visual acuity or loss of normal eye movement (due to damage to cranial nerves III, IV, and VI as they pass through the cavernous sinus). Symptomatic CCFs should be treated to preserve eye function. Fistulae may be closed by balloon occlusion using interventional neuroradiology techniques. Fistulae with wide necks are difficult to treat and may require total occlusion of the parent carotid artery. Neurosurgery Cardinal signs of intracranial hypertension include all of the following except: (A) flexor (decorticate) posturing (B) papilledema (C) aphasia (D) dilated and nonreactive pupil Neurosurgery Cardinal signs of intracranial hypertension include all of the following except: (A) flexor (decorticate) posturing (B) papilledema (C) aphasia (D) dilated and nonreactive pupil Neurosurgery Explanation: Intracranial hypertension may be defined as an ICP greater than 20 cmH2O. Any process that increases the volume within the intracranial compartment may cause intracranial hypertension, such as hydrocephalus, cerebral edema, or a space occupying lesion. The most consistent and one of the only early signs of intracranial hypertension is papilledema. The other common signs of elevated ICP usually develop late and are related to brain herniation. Aphasia is usually the result of ischemia or a focal mass lesion interfering with the temporo-parietal area of the dominant hemisphere. It is not regarded as a hallmark of intracranial hypertension. Neurosurgery Late complications of traumatic brain injury may include all of the following except: (A) seizures (B) communicating hydrocephalus (C) primary brain tumors (D) memory impairment Neurosurgery Late complications of traumatic brain injury may include all of the following except: (A) seizures (B) communicating hydrocephalus (C) primary brain tumors (D) memory impairment Neurosurgery Explanation: Well-documented late complications of head injury include seizures, communicating hydrocephalus, postconcussion syndrome, and varying degrees of intellectual impairment. Other documented late complications include hypogonadotropic hypogonadism and the deposition of amyloid proteins, which may be related to the development of Alzheimer's disease. As a recent Swedish study supports, there is no association between traumatic head injury and primary brain tumors. Neurosurgery A 22-year-old female presents to the emergency department as a level II trauma after falling off a horse and hitting her head on the ground. She had brief loss of consciousness and is now oriented to name and place only. The patient has no apparent systemic injuries. A CT scan of the head shows mild generalized cerebral edema. What is the most appropriate intravenous fluid for this patient? (A) Ringer's lactate (B) 0.225% NS with 20 meq KCl (C) 0.45% NS with 20 meq KCl (D) 0.9% NS with 20 meq KCl Neurosurgery A 22-year-old female presents to the emergency department as a level II trauma after falling off a horse and hitting her head on the ground. She had brief loss of consciousness and is now oriented to name and place only. The patient has no apparent systemic injuries. A CT scan of the head shows mild generalized cerebral edema. What is the most appropriate intravenous fluid for this patient? (A) Ringer's lactate (B) 0.225% NS with 20 meq KCl (C) 0.45% NS with 20 meq KCl (D) 0.9% NS with 20 meq KCl Neurosurgery • Explanation: Management of intravenous fluids in headinjured patients is one area where trauma surgeons and neurosurgeons often disagree. Although reasons to convert to hypotonic solutions may develop, the initial choice for head-injured patients is isotonic solution. Hypotonic solutions should be avoided if possible, because they may impair cerebral compliance and worsen cerebral edema. With an intact blood-brain barrier, hypertonic solutions can establish an osmotic gradient that actually drives water out of the brain and into plasma. This is the principal method of action of mannitol, the most wellstudied and proven osmotic diuretic for lowering ICP. Neurosurgery • Explanation: In addition to mannitol, hypertonic saline has been shown in recent studies to lower ICP. A recent literature review concluded that hypertonic saline has favorable effects on both systemic hemodynamics and ICP. The most deleterious side effect of these agents is renal failure secondary to a hyperosmolar state and renal hypoperfusion. Therefore, urine output, serum osmolality, and serum sodium must be monitored closely when using hypertonic agents. Other basic fluid management principles to keep in mind when treating a head-injured patient include the following: provide adequate resuscitation to avoid hypotension, maintain patient in euvolemia, and consider pressors over repeated fluid boluses. Neurosurgery A 24-year-old male is taken to the emergency department after being involved in a motor vehicle accident approximately 3 h ago. The patient was the unrestrained driver, and he cannot recall the accident. He complains of a left-sided headache, and you notice on physical examination that he has a palpable deformity over the left side of his skull and a boggy temporalis muscle. You order a CT scan of the head. The nurse calls you 20 min later to see the patient, because he has suddenly become unresponsive. A CT scan of the head is most likely to reveal what type of lesion? (A) chronic subdural hematoma (B) diffuse subarachnoid hemorrhage (C) intraventricular hemorrhage (D) epidural hematoma Neurosurgery A 24-year-old male is taken to the emergency department after being involved in a motor vehicle accident approximately 3 h ago. The patient was the unrestrained driver, and he cannot recall the accident. He complains of a left-sided headache, and you notice on physical examination that he has a palpable deformity over the left side of his skull and a boggy temporalis muscle. You order a CT scan of the head. The nurse calls you 20 min later to see the patient, because he has suddenly become unresponsive. A CT scan of the head is most likely to reveal what type of lesion? (A) chronic subdural hematoma (B) diffuse subarachnoid hemorrhage (C) intraventricular hemorrhage (D) epidural hematoma Neurosurgery • Explanation: Epidural hematomas comprise about 1% of all head trauma admissions. An epidural hematoma is defined as a blood clot that forms between the dura and the inner table of the skull. The classic presentation of an epidural hematoma, only occurring a minority of the time, is a young adult who has a brief loss of consciousness followed by a lucid interval for several hours. This is then followed by obtundation, contralateral hemiparesis, and ipsilateral pupillary dilation (signs of uncal herniation as described in question 5). Death may result from continued compression of the midbrain causing bradycardia and respiratory distress. Overall mortality from epidural hematomas ranges from 20 to 55%, with prompt diagnosis and treatment lowering this rate to 5 to 10%. Neurosurgery • Explanation: The most common location for an epidural hematoma is temporoparietal, and the most common cause is a tear in a branch of the middle meningeal artery. A temporoparietal skull fracture is the usual offending injury. Other sources of bleeding include meningeal veins and dural sinuses. The classic CT finding for an epidural hematoma is a biconvex, hyperdense area adjacent to the skull. The hematoma is usually limited to a small area of the skull and does not cross suture lines. Generally accepted indications for removing an epidural hematoma in the operating room include any symptomatic epidural or an acute asymptomatic epidural that is greater than 1 cm at its widest portion since these tend not to resorb. Additionally, the threshold for operating on pediatric patients is lower than for adults since children have less available intracranial space to accommodate a blood clot. Neurosurgery What category of subdural hematoma appears isodense to brain on CT scans? (A) acute (B) subacute (C) chronic (D) none of these Neurosurgery What category of subdural hematoma appears isodense to brain on CT scans? (A) acute (B) subacute (C) chronic (D) none of these Neurosurgery • Explanation: The brain is covered by the meninges which include pia (a thin membrane tightly adherent to the brain), arachnoid, and dura. A subdural hematoma is a hemorrhage that occurs between the dura and arachnoid membrane. Subdural hematomas may be divided radiographically into three categories: acute, subacute, and chronic. An acute subdural hematoma is seen within 3 days of the initial hemorrhage and appears hyperdense to brain on CT scans. A subacute subdural hematoma forms between 4 days and 3 weeks following the initial hemorrhage and appears isodense to brain on CT scans. A chronic subdural hematoma may be seen after 3 weeks following the initial hemorrhage and appears hypodense to brain on CT scans. All categories of subdural hematomas usually appear as concave fluid collections that spread out over the convexity of the brain. Subdural hematomas may also occur along the tentorium cerebelli, along the interhemispheric fissure, and in the posterior fossa. Neurosurgery Neurosurgery Generally accepted criteria for elevating a depressed skull fracture in the operating room include all of the following except: (A) open fracture (B) coexistence of other traumatic lesion (i.e., hematoma) underlying fragment (C) dural tear with CSF leak (D) involvement of the anterior wall of the frontal sinus Neurosurgery Generally accepted criteria for elevating a depressed skull fracture in the operating room include all of the following except: (A) open fracture (B) coexistence of other traumatic lesion (i.e., hematoma) underlying fragment (C) dural tear with CSF leak (D) involvement of the anterior wall of the frontal sinus Neurosurgery Explanation: Depressed skull fractures are caused by a significant force being applied to a relatively small area of the head. The modality of choice for diagnosing depressed skull fractures is a CT scan of the head. Although recently disputed, generally accepted criteria for elevating a depressed skull fracture in the operating room include open depressed fractures, coexistence of an underlying traumatic lesion, dural tear with CSF leak, and cosmetic deformity. A fracture of the anterior wall of the frontal sinus would only require surgical repair if it caused a significant cosmetic deformity, and this could be done on an elective basis. A fracture through the posterior wall, however, is in a different category because communication between the sinus and brain increases the risk of developing meningitis or a cerebral abscess. Neurosurgery A 19-year-old male presents to the emergency department after being shot in the head with a handgun. Appropriate initial steps in managing this patient include all of the following except: (A) begin Solumedrol protocol (B) control scalp bleeding (C) elevate HOB to 30–45% (D) give mannitol 1 g/kg bolus Neurosurgery A 19-year-old male presents to the emergency department after being shot in the head with a handgun. Appropriate initial steps in managing this patient include all of the following except: (A) begin Solumedrol protocol (B) control scalp bleeding (C) elevate HOB to 30–45% (D) give mannitol 1 g/kg bolus Neurosurgery • Explanation: Treatment of a GSW to the head include cardiopulmonary resuscitation as needed, endotracheal intubation if airway is compromised, cervical spine precautions, control scalp bleeding, shave the scalp, and obtain a noncontrast CT scan of the brain. In addition, one must assume that the ICP is elevated in a patient with a gunshot wound to the head. Therefore, initial measures must be taken to control the patient's ICP. These steps are elevating the head of bed to 30–45%, keeping the head in midline position, administering a 1 gm/kg bolus of mannitol as blood pressure permits, and mild hyperventilation (PCO2 = 35). The efficacy of steroids in penetrating head injuries is unsubstantiated and is therefore not recommended. Neurosurgery Diffuse axonal injury (DAI) results from what type of force acting on the brain? (A) direct impact (B) axial loading (C) linear acceleration (D) rotational acceleration Neurosurgery Diffuse axonal injury (DAI) results from what type of force acting on the brain? (A) direct impact (B) axial loading (C) linear acceleration (D) rotational acceleration Neurosurgery • Explanation: DAI refers to a characteristic brain injury pattern. The patient presents with unconsciousness and a lack of a focal mass lesion on CT scanning. Neuronal damage results from shearing of the axons that is caused by rotational acceleration forces. These same forces cause shearing of small blood vessels as well. Skull fractures are less common in patients with DAI than in those with a focal lesion. The rotational forces necessary to cause DAI most commonly occur in motor vehicle accidents. In motor vehicle accidents, the head makes contact with a relatively soft, broad surface such as a padded dashboard or energy-absorbing steering column resulting in a long period of acceleration within the skull. This longer period of acceleration translates into greater shearing and deformation of brain tissue. Neurosurgery Neurosurgery Neurosurgery Neurosurgery Neurosurgery Neurosurgery The overall mortality rate from deep venous thromboses in patients with spinal cord injuries is (A) 1% (B) 5% (C) 10% (D) 20% Neurosurgery The overall mortality rate from deep venous thromboses in patients with spinal cord injuries is (A) 1% (B) 5% (C) 10% (D) 20% Neurosurgery • Explanation: Patients with spinal cord injuries have a relatively high risk for developing deep venous thrombosis, especially with higher levels of injury. The overall mortality from deep venous thromboses in patients with spinal cord injury is approximately 10%. Death may result from pulmonary embolus or embolic stroke if the patient has a patent foramen ovale. Because of this risk, patients with spinal cord injury should be on some form of deep venous thrombosis prophylaxis. This may include passive lower extremity motion, pneumatic compression boots, and heparin delivered subcutaneously. Additionally, physicians caring for patients with spinal cord injuries should have a high index of suspicion and a low threshold for diagnosing and treating deep venous thromboses in these patients. Neurosurgery A painful thoracic compression fracture secondary to the osteoporosis that accompanies Cushing's disease is best treated by (A) prolonged bed rest and narcotics (B) methylmethacrylate injection (C) endoscopic transthoracic stabilization (D) bracing and medical therapy for osteoporosis Neurosurgery A painful thoracic compression fracture secondary to the osteoporosis that accompanies Cushing's disease is best treated by (A) prolonged bed rest and narcotics (B) methylmethacrylate injection (C) endoscopic transthoracic stabilization (D) bracing and medical therapy for osteoporosis Neurosurgery • Explanation: Vertebroplasty has revolutionized the management of osteoporotic compression fractures. Injection of methylmethacrylate into the vertebral body via a needle introduced through the pedicle is safe and effective in giving almost immediate relief of pain.