SMLE Surgery Syllabus

State the mean arterial pressure formula and calculate MAP for BP $120/60$.

$$MAP = DBP + \tfrac{1}{3}(SBP - DBP)$$ For $120/60$: $MAP = 60 + \tfrac{1}{3}(120-60) = 60 + 20 = 80\,\text{mmHg}$.

What are the initial ICP-lowering measures in acute head injury?

Elevate head of bed to $30^\circ$, keep head midline, ensure adequate oxygenation and normocapnia ($PaCO_2 \approx 35\text{-}40\,\text{mmHg}$), avoid hypotension, sedation/analgesia, osmotherapy (mannitol $0.25\text{-}1\,\text{g/kg}$ or hypertonic saline), and treat seizures. Hyperventilation only as temporary rescue.

What are the immediately life-threatening chest injuries identified in the primary survey (ATLS)?

The 'lethal six'/primary survey threats: airway obstruction, tension pneumothorax, open pneumothorax, massive hemothorax, flail chest (with pulmonary contusion), and cardiac tamponade.

Describe the classic signs of tension pneumothorax and its immediate management.

Signs: severe dyspnea, hypotension, distended neck veins, tracheal deviation away from the affected side, absent breath sounds and hyperresonance on the affected side. Management: immediate needle decompression (2nd intercostal space, midclavicular line, or 4th-5th ICS anterior axillary line) followed by chest tube.

How is massive hemothorax defined and what triggers thoracotomy?

Massive hemothorax = $> 1500\,\text{mL}$ blood initially, or $\geq 200\,\text{mL/hr}$ for $2\text{-}4$ hours via chest tube. It requires large-bore chest tube drainage plus surgical thoracotomy for ongoing bleeding and volume resuscitation.

What is Beck's triad, and which chest injury does it indicate?

Beck's triad = hypotension, muffled/distant heart sounds, and distended neck veins (raised JVP). It indicates cardiac tamponade; pulsus paradoxus may also be present. Management: pericardiocentesis or pericardial window/thoracotomy.

Define flail chest and its principal cause of hypoxia.

Flail chest = $\geq 2$ adjacent ribs fractured in $\geq 2$ places, producing a free segment with paradoxical movement. The main cause of hypoxia is the underlying pulmonary contusion, not just the paradoxical motion; treat with analgesia, O$_2$, and ventilatory support as needed.

What is the difference between open and closed pneumothorax, and how is an open ('sucking') chest wound initially managed?

Closed: air in pleural space, chest wall intact. Open: full-thickness chest wall defect communicating with pleura ('sucking chest wound'). Initial management: three-sided occlusive dressing (flutter-valve effect) then definitive chest tube; converting to full seal risks tension pneumothorax.

What regions define the anatomical borders of the abdomen relevant to trauma assessment?

Anterior abdomen: costal margins to inguinal ligaments, between anterior axillary lines. Flank: between anterior and posterior axillary lines (6th ICS to iliac crest). Back: posterior to posterior axillary lines. The thoracoabdominal region (nipple line/4th ICS to costal margin) may involve both chest and abdomen.

Which two solid organs are most commonly injured in blunt abdominal trauma?

The spleen (most common in blunt trauma) and the liver. Both can cause significant intraperitoneal hemorrhage and are key targets of FAST and CT evaluation.

What does FAST examine and what are its four standard windows?

FAST (Focused Assessment with Sonography in Trauma) detects free intraperitoneal/pericardial fluid. Four windows: right upper quadrant (Morison's pouch/hepatorenal), left upper quadrant (splenorenal), pelvis (pouch of Douglas/rectovesical), and pericardial (subxiphoid). eFAST adds bilateral thoracic views for pneumo/hemothorax.

In hemodynamically unstable blunt abdominal trauma, what does a positive FAST indicate?

A positive FAST (free fluid) in an unstable patient indicates intraperitoneal hemorrhage and is an indication for emergency laparotomy without waiting for CT.

When is CT versus laparotomy versus DPL preferred in abdominal trauma?

Hemodynamically stable: CT abdomen/pelvis with contrast (most sensitive for solid organ and retroperitoneal injury). Unstable with positive FAST: immediate laparotomy. DPL (diagnostic peritoneal lavage) is largely replaced by FAST but may be used when ultrasound is unavailable/equivocal.

What are the four ATLS classes of hemorrhagic shock by percent blood volume lost?

Class I: $< 15\%$ ($<750\,\text{mL}$), normal vitals. Class II: $15\text{-}30\%$ ($750\text{-}1500\,\text{mL}$), tachycardia, narrowed pulse pressure. Class III: $30\text{-}40\%$ ($1500\text{-}2000\,\text{mL}$), hypotension, altered mental status. Class IV: $> 40\%$ ($>2000\,\text{mL}$), life-threatening, lethargy.

What is the ABCDE sequence of the ATLS primary survey?

A: Airway with cervical spine protection. B: Breathing and ventilation. C: Circulation with hemorrhage control. D: Disability (neurologic status, GCS, pupils). E: Exposure/environment (undress, prevent hypothermia).

Which physical signs on abdominal exam mandate laparotomy in trauma?

Peritonitis (guarding, rebound, rigidity), evisceration, hemodynamic instability with positive FAST/peritoneal signs, free air on imaging, blood from NG tube or rectum, and gunshot wounds that penetrate the peritoneum.

What is the recommended crystalloid strategy and blood ratio in trauma resuscitation?

Limit crystalloid; give balanced/warmed fluids and move early to blood products. Massive transfusion uses a balanced ratio approaching $1{:}1{:}1$ of packed red cells, fresh frozen plasma, and platelets. Permissive hypotension may be targeted until hemorrhage control in penetrating trauma.

Define atelectasis as a postoperative complication and its typical timing.

Atelectasis is collapse of alveoli, the most common cause of fever in the first $24\text{-}48$ hours postoperatively. Managed with incentive spirometry, deep breathing, early mobilization, and adequate analgesia.

What is the classic timeline ('the W's') for postoperative fever causes?

Wind (atelectasis/pneumonia, days 1-2), Water (UTI, days 3-5), Wound (surgical site infection, days 5-7), Walking (DVT/thrombophlebitis, days 5+), Wonder drugs / What did we do (drug fever, IV lines, day 7+).

What are the components of Virchow's triad for postoperative venous thromboembolism?

1) Venous stasis (immobility, anesthesia). 2) Endothelial injury (surgery, catheters). 3) Hypercoagulability (tissue trauma, malignancy, dehydration). All three raise DVT/PE risk; prophylaxis uses early mobilization, mechanical compression, and LMWH.

Differentiate wound dehiscence from evisceration and give a warning sign.

Dehiscence: partial or complete separation of the wound layers. Evisceration: protrusion of abdominal viscera through a full-thickness dehiscence (surgical emergency—cover with saline gauze, urgent OR). A serosanguinous ('salmon-pink') discharge from the wound often heralds impending dehiscence.

How is postoperative ileus distinguished from mechanical small bowel obstruction?

Postoperative ileus: functional, diffusely absent/reduced bowel sounds, gas throughout bowel including colon on imaging, usually resolves in 3-5 days with bowel rest. Mechanical SBO: colicky pain, high-pitched/tinkling sounds, air-fluid levels with a transition point and distal decompression; may need surgery.

What are the standard components of surgical site infection prevention (prophylactic antibiotics timing)?

Give IV prophylactic antibiotics within $60$ minutes before skin incision ($120$ min for vancomycin/fluoroquinolones), appropriate to the operative flora, redose for long procedures or major blood loss, and generally discontinue within $24$ hours postoperatively.

Define primary versus secondary hemorrhage in the postoperative period.

Primary hemorrhage: bleeding during or immediately after surgery from inadequate hemostasis. Reactionary/reactive: within 24 hours as BP normalizes and a clot/ligature dislodges. Secondary hemorrhage: 7-14 days later, usually due to infection eroding a vessel.

What is the Parkland formula for burn fluid resuscitation?

$$V = 4\,\text{mL} \times \text{weight(kg)} \times \%\text{TBSA burned}$$ Give half in the first 8 hours (from time of injury) and the remaining half over the next 16 hours, using lactated Ringer's; titrate to urine output ($0.5\text{-}1\,\text{mL/kg/hr}$).

How is Total Body Surface Area estimated using the 'Rule of Nines' in adults?

Head $9\%$, each arm $9\%$, anterior trunk $18\%$, posterior trunk $18\%$, each leg $18\%$, perineum $1\%$. The patient's palm (with fingers) approximates $1\%$ TBSA for scattered burns.

What is the difference between the raccoon eyes/Battle's sign and CSF rhinorrhea in head trauma?

Raccoon eyes (periorbital ecchymosis) and Battle's sign (mastoid ecchymosis) suggest basilar skull fracture. CSF rhinorrhea/otorrhea (halo/ring sign on gauze; fluid positive for $\beta_2$-transferrin) confirms a dural tear allowing CSF leak.

What criteria (Canadian CT Head Rule concept) prompt CT imaging after minor head injury?

CT indicated if: GCS $< 15$ at 2 hours, suspected open/depressed skull fracture, signs of basilar skull fracture, $\geq 2$ episodes of vomiting, age $\geq 65$, dangerous mechanism, or amnesia $> 30$ min before impact (plus anticoagulation/coagulopathy as an additional flag).

What is the pathophysiology and management priority of a pulmonary contusion after chest trauma?

Pulmonary contusion is alveolar/interstitial hemorrhage and edema from blunt force, causing progressive hypoxia and a ventilation-perfusion mismatch over 24-48 hours. Management: oxygenation, pain control, judicious fluids (avoid overload), pulmonary toilet, and ventilatory support if respiratory failure develops.

What is 'damage control surgery' in severe abdominal/torso trauma and its physiologic rationale?

An abbreviated initial operation to control hemorrhage and contamination (packing, temporary closure) rather than definitive repair, allowing correction of the 'lethal triad' of hypothermia, acidosis, and coagulopathy in the ICU before planned re-operation.