Surgery Volume 1 Marrow Edition 8 - Study Notes

Clinical Expertise and Educational Guidelines

Dr. Rohan Khandelwal, MS (General Surgery), MRCS (Edin.), FIBD, FICS, is an onco-plastic breast surgeon who received training at the University of Maryland (USA). He has successfully headed a Breast Cancer Unit for the last ten years and is currently based at CK Birla Hospital in Gurgaon. With over fourteen years of teaching experience, he provides these transcripts from the Marrow Video editions as a comprehensive educational guide. These notes serve as an exhaustive transcription of the Marrow Edition 8 surgery modules and are designed to be used in conjunction with the instructional videos. The materials within are intended strictly for educational purposes and should not substitute for professional medical diagnosis or treatment.

Patient Identification and Pre-Operative Consent

Surgical consent represents a critical legal and ethical requirement consisting of several mandatory components. It must include patient identification, the specific diagnosis, and the procedure planned. The surgeon must be explicitly named, and a detailed description of the procedure is required. Consent must cover patient-specific complications as well as procedure-specific complications, defined as any complication with a greater than $1\%$ incidence. Furthermore, the benefits of the surgery and alternate procedures must be discussed. The document is finalized by the signatures of the patient, the surgeon, and a witness.

Access Management and Intravenous Cannulation

Intravenous (IV) cannulas are standardized by a color-coding system related to their gauge and maximal flow rate. The yellow cannula is $24G$ with a flow rate of $13\,ml/min$ (or $10$ according to some variations) and is used primarily for pediatric patients. The blue cannula is $22G$ with a flow rate of $31\,ml/min$ ($30$), followed by pink at $20G$ and $67\,ml/min$ ($60$). For adult patients requiring wide-bore access, the green cannula is $18G$ ($96\,ml/min$), gray is $16G$ ($236\,ml/min$ or $240$), and orange is the largest at $14G$ ($270\,ml/min$), specifically used in shock management. The most common complication of IV cannulation is superficial thrombophlebitis, characterized by tender, cord-like swelling, which is managed using topical heparinoids.

Surgical Safety Checklist and Operating Room Zoning

The Surgical Safety Checklist is divided into three critical phases. The 'Sign In' occurs before the induction of anesthesia, where the patient confirms identity, site, procedure, and written consent, and the team identifies known allergies and risks of blood loss exceeding $500\,ml$. The 'Time Out' happens before the skin incision, confirming patient site, procedure name, and timing, and ensuring antibiotic prophylaxis was given within the last $30\,min$. The 'Sign Out' occurs before the patient leaves the operating room, where the team counts instruments, sponges, and needles, ensures specimen labeling, and records actual blood loss as determined by the anesthetist. Operating Theatre (OT) zoning is categorized into four zones: the Protective Zone (change rooms, transfer bay, ICU/PACU), the Clean Zone (equipment store and maintenance), the Aseptic Zone (the OT itself), and the Disposal Zone. Blood loss estimation is performed by subtracting irrigation fluid from the blood in suction or by weighing mops; a soaked mop typically contains $100\,cc$ of blood, while a fistful of clots represents approximately $500\,cc$.

Patient Positioning and Complication Mitigation

Supine or neutral position is the most common approach for abdominal and breast surgeries. The Trendelenburg position involves a head-end low and foot-end up configuration and is used for pelvic surgeries. Conversely, the Reverse Trendelenburg position is used in upper abdominal surgeries and laparoscopic cholecystectomy; a common complication is right shoulder tip pain due to $CO_2$ collecting below the right diaphragm. The Lithotomy position is utilized for obstetric, gynecologic, urologic (TURP), and hemorrhoid surgeries; however, the common peroneal nerve is at risk if legs are poorly supported. The Lateral or Kidney position is used for thoracotomy, nephrectomy, and breast reconstruction using Latissimus Dorsi flaps, but it increases the risk for brachial plexus injury due to hyperextended arms. The Prone position is used for spinal and pilonidal sinus surgery. The Sitting or Fowler’s position is used for posterior cranial fossa surgery, offering a bloodless field and increased exposure but carries a significant risk of air embolism. The Jackknife position is considered obsolete due to the risk of positional asphyxia. The Lloyd Davies position combines Trendelenburg and Lithotomy and is favored in rectal cancer surgeries.

Air Embolism in Surgical Procedures

Air embolism occurs when $50-100\,cc$ of air is sucked into a vein, entering the circulation and dysregulating cardiac function. Risk factors include head and neck surgeries or procedures performed in the Fowler’s position. Clinical signifiers include sudden desaturation, dyspnea, and hypotension. Prevention strategies involve ligating veins before cutting and irrigating the surgical field. Management requires placing the patient in the Durant position (Left lateral with legs up/Right side up) and aspirating air using a central line or direct puncture.

Surgical Instrumentation: Blades and Incisions

Surgical blades are numbered according to their specific utility. The No. 10 blade is used to make standard incisions, while the No. 15 is smaller for finer work. No. 22 and No. 23 are larger blades. The No. 11 blade is a pointed 'stab blade' used for incision and drainage of abscesses or for arteriotomy. The No. 12 blade is curved and used specifically for suture removal. Blades are passed in a kidney tray with the pointed end facing the self and are mounted on a Bard Parker (BP) handle. The sharpest portion is the belly of the blade. Incisions should be made perpendicular to the skin and follow Langer’s lines (relaxed tension lines). Incisions parallel to these lines result in better scarring as they align with dermal collagen fibers.

Surgical Energy Sources and Electrocautery Waveforms

Monopolar cautery utilizes a circuit consisting of a machine, a Bovie tip, and a cautery pad. The pad must be placed over a well-vascularized area with a wide contact surface; a small pad or incomplete circuit can cause site burns or mechanical failure. Disadvantages include lateral spread of current and interference with cardiac pacemakers. Bipolar cautery completes the circuit locally between two prongs, making it safe for use near vital structures, end arteries, and pacemakers, though it only offers a coagulation mode. Current patterns include Cutting Current, which is low voltage and continuous, causing cell water explosion through heat. Coagulation Current is high voltage and alternating/interrupted, leading to dehydration and protein denaturation. Blend mode combines both. Fulguration is a type of coagulation with higher voltage peaks.

Advanced Tissue Dissection and Hemostatic Technology

Ligasure uses heat and pressure to seal and divide tissue using body collagen and elastin, with an automatic feedback mechanism that discontinues seal closure. It is effective for vessels up to $7\,mm$ in diameter but cannot be used near vital structures. The Harmonic Scalpel works on an ultrasonic principle where a blade oscillates between $20,000-50,000\,Hz$, causing protein denaturation and coagulation without heat production; it allows for precise cuts through scar tissue. The Cavitron Ultrasonic Surgical Aspirator (CUSA) is a type of harmonic scalpel used in liver resection, as hepatocytes are susceptible to oscillatory fragmentation due to high water content; it is notably more effective in non-cirrhotic livers. Thunderbeat S combines the features of Ligasure and Harmonic Scalpel. Radio Frequency Ablation (RFA) uses high-frequency alternating current and a grounding pad for liver tumor resection up to $3\,cm$. Microwave Ablation uses oscillation and frictional heat, requiring no grounding pad and offering a more homogenous zone of ablation in less time than RFA.

Surgical Drains and Knot-Tying Principles

Surgical drains are classified as open or closed. The Romovac is a closed suction drain with negative pressure used after mastectomy or thyroidectomy but is avoided in the abdomen due to the risk of bowel perforation. The Minivac is used after sentinel lymph node biopsy. The Jackson Pratt drain is a bulb-style negative pressure drain with flat tubes, allowing abdominal use. Abdominal drains can also be closed without negative pressure. Underwater seal bags submerged in water prevent air from being sucked into the chest during drainage. Knot types include the Square or Reef knot, which consists of one throw followed by another with opposite crossings. The Surgeon’s knot involves two throws followed by a square knot. A Granny or Slip knot is a result of not crossing throws correctly and is prone to opening.

Principles of Skin Suturing and Needle Selection

Proper skin suturing requires everted edges and a needle entry at $90^{\circ}$. The bite on each side ($x$) should be half the distance between sutures ($2x$). Types include simple sutures, mattress sutures (vertical or horizontal for eversion and hemostasis), and subcuticular sutures (Monocryl $3-0$ on a cutting needle for cosmetic results). The Aberdeen or Cobbler’s knot is used as a continuous lock suture for closing cavities, while the purse-string suture is used for the appendicular stump or cervical encerclage. Round body needles split tissue and are used for bowel, bladder, blood vessels, and the common bile duct. Cutting or reverse-cutting needles cut tissue and are used for tough structures like the sheath, skin, and fascia. The needle holder should grasp the needle at the junction of the distal $1/3rd$ and proximal $2/3rds$.

Synthetic and Natural Suture Materials

Sutures are color-coded: Brown for Catgut, Violet for Vicryl, Blue for Prolene, and Black for Silk. Suture numbering indicates diameter ($1.0$ is thick, $11.0$ is very fine). Natural sutures (Silk, Catgut) are often antigenic and provoke inflammatory reactions, dissolving by proteolysis. Synthetic sutures (Prolene, PDS, Vicryl) are inert, causing less inflammation and dissolving through hydrolysis. Monofilaments (Prolene, PDS, Nylon, Monocryl) have high memory and require more knots but are difficult to handle. Braided sutures (Vicryl, Silk) are easier to handle but carry a higher risk of infection. Specific uses include Catgut (phagocytosis in $7-10$ days), Chromic Catgut (tensile strength $21-28$ days), Monocryl (subcuticular), Vicryl Rapid (dissolves in $21-28$ days), Prolene (mesh and vascular repair), and Nylon ($10-0$ for cataract surgery). Jenkins' Rule for abdominal sheath closure states the suture length must be at least $4\,times$ the length of the wound. Suture removal timing varies: Face ($3-5$ days), Scalp/Neck ($5-7$ days), Abdomen ($12-14$ days), and Thorax ($10-12$ days).

Post-Operative Fever and Pulmonary Complications

Post-operative fever has distinct etiologies based on the timing post-surgery. On post-op day (POD) $1$, the most common cause is atelectasis (collapse of alveoli), prevented by incentive spirometry, smoking cessation $4-6$ weeks prior, and steam inhalation. On POD $2-3$, causes include pneumonia, superficial thrombophlebitis, or Urinary Tract Infections (UTI). POD $4-5$ often indicates Surgical Site Infections (SSI). POD $6$ is associated with Deep Vein Thrombosis (DVT) or abdominal wound dehiscence. Beyond POD $7$, intra-abdominal abscesses are common. DVT presents with swelling and pain, diagnosed via Duplex scan and prevented through early ambulation, pneumatic stockings, and Low Molecular Weight Heparin.

Abdominal Wound Dehiscence and Burst Abdomen

Burst abdomen presents as the opening of the rectus sheath with bowel visualization, often preceded by a serous or 'salmon fluid' sign on the dressing on POD $6$. Emergency management involves repositing the bowel and applying a Urobag or Bogota bag (laparostomy), while definitive management is resuturing in the operating room. Risk factors for dehiscence include patient factors (obesity, malnutrition, chronic cough, constipation) and surgeon factors (midline incisions, short bites of $0.5\,cm$ instead of long bites of $1\,cm$, and having a suture-to-wound length ratio less than $4:1$). Intra-abdominal abscesses are commonly located in the pelvis or Pouch of Douglas, or in the Morrison’s pouch (right hepatorenal pouch) in supine patients. Pelvic abscesses present with pelvic diarrhea and urinary frequency, diagnosed by CECT and drained via USG-guided pigtail catheters.

Surgical Site Infections and Wound Classification

Surgical Site Infection (SSI) is defined as a wound infection occurring within $30$ days of surgery (or $1$ year if an implant is present). SSI criteria incorporate the ASEPSIS or Southampton wound scores. Wounds are categorized into four classes. Class I: Clean wounds (e.g., thyroid, breast, elective hernia) with a $1-2\%$ SSI risk. Class II: Clean-contaminated (e.g., elective cholecystectomy or prepared bowel surgery) with a $6-9\%$ risk without prophylaxis. Class III: Contaminated (e.g., emergency cholecystectomy, open cardiac massage, or bowel injury during obstruction surgery) with a $20\%$ risk. Class IV: Dirty wounds (e.g., abscesses or fecal peritonitis) which have a $20-40\%$ risk. Prophylactic antibiotics are not indicated for clean wounds unless a mesh or implant is used. The 'decisive period' for antibiotic efficacy is within $4$ hours of the skin incision.

Prevention and Management of Wound Infections

Prevention centers on hand hygiene, requiring a minimum of $3\,minutes$ of handwashing. The five moments of hand hygiene include before and after touching a patient or their surroundings, after fluid exposure, and before aseptic procedures. Hair removal should be performed with a hair clipper rather than shaving to avoid micro-abrasions. Skin preparation using Chlorhexidine and alcohol is superior to Betadine. Operating Theatre parameters require laminar air flow using HEPA filters with $90\%$ efficiency for particles larger than $0.5\,mm$, an optimum temperature of $18-22^{\circ}C$, and $50-60\%$ relative humidity. Hypothermia and hyperglycemia should be prevented. Post-operatively, giving oxygen helps in healing.

Day Care Surgery and Patient Selection Criteria

Day care surgery requires the patient to be admitted and discharged within $12$ hours. Selection is based on physiological age rather than chronological age. Suitable candidates typically have an ASA Class I or II status, though Class III patients may be treated within hospital-integrated units. BMI thresholds are generally set at $\\le 38$ for laparoscopic procedures and $\\le 40$ for surface procedures. Laboratory benchmarks include an $HbA1c < 8.5\%$ and blood pressure below $180/100$. Socially, the patient must have a responsible adult available for $24$ hours post-discharge and reliable home conditions. The most common complication requiring readmission is hemorrhage, which can be primary (during surgery), reactionary ($4-24$ hours after), or secondary (days after, due to infection). Post-operative nausea and vomiting (PONV) is the most common minor complication, predicted using the Apfel score. Discharge relies on stable vitals for at least $1\,hour$, adequate pain control, ability to dress/walk, and the passage of urine if applicable.

Enhanced Recovery After Surgery (ERAS) Protocol

The ERAS protocol optimizes patient outcomes through preoperative, intraoperative, and postoperative adjustments. Preoperatively, it emphasizes patient counseling, avoiding mechanical bowel prep, solid food up to $6$ hours prior, carbohydrate loading $2-3$ hours prior, and clear liquids up to $2$ hours prior. Intraoperatively, it focuses on minimally invasive approaches, using local anesthetics (liposomal bupivacaine), maintaining patient warmth, and IV fluid maintenance. Postoperatively, the goal is reaching a regular diet, discontinuing IV fluids, and ambulating the patient within $24$ hours while using NSAIDs and gabapentin to minimize opioid use.

Nutritional Assessment in the Surgical Patient

There is no single biochemical marker for malnutrition, though low albumin is an indicator of poor outcome, and pre-albumin serves as a more sensitive marker. Significant weight loss is defined as unintentional loss of more than $10\%$ of body weight within $6$ months. Other indicators include BMI less than $15$, skin fold thickness for body fat, and mid-arm circumference for muscle mass. The Malnutrition Universal Screening Tool (MUST) combines BMI, weight loss, and acute disease scores. Resting energy expenditure (REE) needs to be adjusted based on condition: normal sedentary life requires $20\,kcal/kg/day$, while severe sepsis or burns can increase requirements significantly (up to $40\,kcal/kg/day$).

Enteral and Parenteral Nutrition Modalities

Enteral nutrition is always preferred over parenteral as it is physiological, cheap, maintains enterohepatic circulation, and prevents the translocation of gut bacteria. If oral intake is not possible, Nasogastric (Ryles tube) or Nasojejunal tubes are used for short-term needs ($< 3\,weeks$). For needs exceeding $3\,weeks$, feeding gastrostomy (Stamm, Witzel, or PEG) or feeding jejunostomy (Stamm, Witzel) is performed. Percutaneous Endoscopic Gastrostomy (PEG) involves endoscope advancement, transillumination of the abdominal wall, and suture fixation. Feeding rates for enteral nutrition start gradually at $10-20\,ml/hr$ and increase to $75\,ml/hr$. If the gastric aspirate exceeds $75-100\,cc$, the next feed is withheld to avoid aspiration. Complications include osmotic diarrhea due to hyperosmolar feeds and tube blockage.

Total Parenteral Nutrition (TPN) and Central Access

Total Parenteral Nutrition (TPN) is indicated for prolonged paralytic ileus ($> 72\,hours$), short bowel syndrome, high-output fecal fistula ($> 500\,cc/24\,hrs$), and acute severe pancreatitis. Routes include central lines in the internal jugular or subclavian veins, or Peripherally Inserted Central Catheters (PICC) that last $2-3\,months$. The TPN solution composition is typically $20\%:30\%:50\%$ for protein:fat:carbohydrate. Daily monitoring includes body weight; a weight gain of more than $1\,kg/day$ is the earliest sign of overfeeding. Complications of TPN include catheter-related sepsis (most common), air embolism, pneumothorax, hyperglycemia, and cholestasis (seen in $25\%$ of long-term users). Hyperglycemia is the most common metabolic complication.

Refeeding Syndrome and Post-Operative Fluid Management

Refeeding syndrome occurs when large quantities of nutrition are given to a chronically malnourished patient. The influx of $PO_4^{3-}$, $Mg^{2+}$, $K^+$, and $Ca^{2+}$ into cells due to insulin release leads to severe electrolyte imbalances and fluid overload. Hypophosphatemia is the main driver of the resulting metabolic derangement, which can cause death via heart failure or arrhythmia. Prevention involves a gradual increase in feed ($10\,kcal/kg/day$) and thiamine supplementation. Post-operative fluid maintenance replaces insensible losses (breathing/sweating) at $30-40\,ml/kg/day$. Potassium replacement is not performed on POD $1$ as cell injury causes an initial efflux of $K^+$, but it is started on POD $2$. Hartmann’s solution (RL) provides $131\,mmol/L$ of $Na^+$ and $5\,mmol/L$ of $K^+$, while Normal Saline (NS) provides $154\,mmol/L$ of both $Na^+$ and $Cl^-$. Daily requirements include $50-90\,mmol$ of sodium and $50\,mmol$ of potassium.

Pathophysiology and Classification of Shock

Shock is divided into several types, with hypovolemic/hemorrhagic being the most common surgical type. Clinical hemorrhage can be overt/visible or concealed (neck, thorax, abdomen, pelvis, long bones). Isolated head injury does not typically cause hypotension; if it occurs, one should suspect neurogenic shock or associated trauma. Bleeding is categorized by timing: primary (during surgery), reactionary (within $24\,hours$ due to clot dislodgement), or secondary ($7-14$ days later, usually due to infection). Hypovolemic shock is classified by severity. Class I: Under $15\%$ blood loss ($0.5\,L$). Class II (Mild): $15-30\%$ loss ($1\,L$), characterized by tachycardia and narrow pulse pressure. Class III (Moderate): $30-40\%$ loss ($1.5\,L$), where systolic blood pressure (SBP) falls and the patient is confused. Class IV (Severe): Over $40\%$ loss ($> 2\,L$), with non-recordable SBP and heart rate, leading to coma.

Physiological Responses to Hypovolemic Shock

The physiological response to Class II shock (compensated shock) is driven by the activation of the sympathetic nervous system, releasing adrenaline and noradrenaline to cause tachycardia and peripheral vasoconstriction, shunting blood to vital organs. Dynamic fluid response classifies patients into: Responders (heart rate and SBP stabilize), Transient Responders (improve then worsen), and Non-responders (ongoing losses). Damage control resuscitation prioritizes coagulation and permissive hypotension, maintaining blood pressure at the lower limit of normal with a balanced transfusion ratio of $1:1$ for RBC and FFP. Perfusion-targeted resuscitation in responders focused on achieving adequate preload, afterload, and end-organ perfusion.

Hemodynamic Monitoring and Indicators of Resuscitation

The indicator for fluid resuscitation in adults is a urine output of $> 0.5\,ml/kg/hr$; in children, it should be $> 1\,ml/kg/hr$. The initial fluid requirement is best indicated by Pulmonary Capillary Wedge Pressure (PCWP) rather than Central Venous Pressure (CVP), though CVP is more frequently used. The Shock Index is the ratio of heart rate to SBP; a value $> 0.9$ correlates with higher mortality. The most sensitive indicator for gut mucosa hypoperfusion (often the first area affected by hypovolemic insult) is gut mucosal pH. Mixed venous oxygen saturation ($S_vO_2$) is considered the best end-point of resuscitation, with normal values between $50-70\%$.

Massive Blood Transfusion and Transfusion Complications

Massive blood transfusion is defined as replacing the entire circulating blood volume in $24\,hours$, or giving $> 10\,units$ in $24\,hours$ or $> 4\,units$ in one hour. Complications include hypothermia, hypocalcemia (due to citrate chelating calcium), metabolic alkalosis (citrate toxicity), hyperkalemia (leaked from lysed RBCs), and coagulopathy (the most common cause of death). Transfusion-Related Acute Lung Injury (TRALI) is caused by antibodies against HLA antigens, leading to non-cardiogenic pulmonary edema within $6\,hours$, characterized by patchy infiltrates on X-ray. Transfusion-Associated Cardiac Overload (TACO) involves facial puffiness and pedal edema due to fluid overload, managed with diuretics. Red blood cell transfusion is generally indicated when hemoglobin is $< 6\,g/dL$; for values $6-8\,g/dL$, it is indicated only if ongoing losses are present.

Sepsis terminologies and Surviving Sepsis Guidelines

Systemic Inflammatory Response Syndrome (SIRS) is defined by presence of two or more of: Temperature $> 38^{\circ}C$ or $< 36^{\circ}C$, Heart Rate $> 90\,bpm$, Respiratory Rate $> 20/min$ or $PaCO_2 < 32\,torr$, and WBC $> 12000/mm^3$ or $< 4000/mm^3$. Sepsis is now defined as a Sequential Organ Failure Assessment (SOFA) score $\ge 2$ with documented infection. The Quick SOFA (qSOFA) score includes SBP $< 100\,mmHg$, RR $> 22/min$, and altered mental status. Septic shock is sepsis with fluid-unresponsive hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) $\ge 65\,mmHg$ and a lactate $> 2\,mmol/L$. The 'Sepsis Six' bundles interventions like IV fluids, antibiotics, blood cultures, urine output monitoring, lactate measurement, and oxygen within $60\,minutes$. Intra-abdominal pressure (IAP) monitoring is also relevant in the management of severe abdominal trauma and sepsis.