NEET MDS Lessons
Oral and Maxillofacial Surgery
Airway Management in Medical Emergencies: Tracheostomy and Cricothyrotomy
1. Establishing a Patent Airway
- Immediate Goal: The primary objective in any emergency involving airway obstruction is to ensure that the patient has a clear and patent airway to facilitate breathing.
- Procedures Available: Various techniques exist to achieve this, ranging from nonsurgical methods to surgical interventions.
2. Surgical Interventions
A. Tracheostomy
- A tracheostomy is a surgical procedure that involves creating an opening in the trachea (windpipe) through the neck to establish an airway.
- Indications:
- Prolonged mechanical ventilation.
- Severe upper airway obstruction (e.g., due to tumors, trauma, or swelling).
- Need for airway protection in patients with impaired consciousness or neuromuscular disorders.
- Procedure:
- An incision is made in the skin over the trachea, A tracheostomy incision is made between the second and third tracheal rings, which is below the larynx. The incision is usually 2–3 cm long and can be vertical or horizontaland the trachea is then opened to insert a tracheostomy tube.
- This procedure requires considerable knowledge of anatomy and technical skill to perform safely and effectively.
B. Cricothyrotomy
- Definition: A cricothyrotomy is a surgical procedure that involves making an incision through the skin over the cricothyroid membrane (located between the thyroid and cricoid cartilages) to establish an airway.
- Indications:
- Emergency situations where rapid access to the airway is required, especially when intubation is not possible.
- Situations where facial or neck trauma makes traditional intubation difficult.
- Procedure:
- A vertical incision is made over the cricothyroid membrane, and a tube is inserted directly into the trachea.
- This procedure is typically quicker and easier to perform than a tracheostomy, making it suitable for emergency situations.
3. Nonsurgical Techniques for Airway Management
A. Abdominal Thrust (Heimlich Maneuver)
- The Heimlich maneuver is a lifesaving technique used to relieve choking caused by a foreign body obstructing the airway.
- Technique:
- The rescuer stands behind the patient and wraps their arms around the patient's waist.
- A fist is placed just above the navel, and quick, inward and upward thrusts are applied to create pressure in the abdomen, which can help expel the foreign object.
- Indications: This technique is the first-line approach for conscious patients experiencing airway obstruction.
B. Back Blows and Chest Thrusts
- Back Blows:
- The rescuer delivers firm blows to the back between the shoulder blades using the heel of the hand. This can help dislodge an object obstructing the airway.
- Chest Thrusts:
- For patients who are obese or pregnant, chest thrusts may be more effective. The rescuer stands behind the patient and performs thrusts to the chest, similar to the Heimlich maneuver.
Approaches to the Oral Cavity in Oral Cancer Treatment
In the management of oral cancer, surgical approaches are tailored to the location and extent of the lesions. The choice of surgical technique is crucial for achieving adequate tumor resection while preserving surrounding structures and function. Below are the primary surgical approaches used in the treatment of oral cancer:
1. Peroral Approach
- Indication: This approach is primarily used for small, anteriorly placed lesions within the oral cavity.
- Technique: The surgeon accesses the lesion directly through the mouth without external incisions. This method is less invasive and is suitable for superficial lesions that do not require extensive resection.
- Advantages:
- Minimal morbidity and scarring.
- Shorter recovery time.
- Limitations: Not suitable for larger or posterior lesions due to limited visibility and access.
2. Lip Split Approach
- Indication: This approach is utilized for posteriorly based lesions in the gingivobuccal complex and for performing marginal mandibulectomy.
- Technique: A vertical incision is made through the lip, allowing for the elevation of a cheek flap. This provides better access to the posterior aspects of the oral cavity and the mandible.
- Advantages:
- Improved access to the posterior oral cavity.
- Facilitates the removal of larger lesions and allows for better visualization of the surgical field.
- Limitations: Potential for cosmetic concerns and longer recovery time compared to peroral approaches.
3. Pull-Through Approach
- Indication: This technique is particularly useful for lesions of the tongue and floor of the mouth, especially when the posterior margin is a concern for peroral excision.
- Technique: The lesion is accessed by pulling the tongue or floor of the mouth forward, allowing for better exposure and resection of the tumor while ensuring adequate margins.
- Advantages:
- Enhanced visibility and access to the posterior margins of the lesion.
- Allows for more precise excision of tumors located in challenging areas.
- Limitations: May require additional incisions or manipulation of surrounding tissues, which can increase recovery time.
4. Mandibulotomy (Median or Paramedian)
- Indication: This approach is indicated for tongue and floor of mouth lesions that are close to the mandible, particularly when achieving a lateral margin of clearance is critical.
- Technique: A mandibulotomy involves making an incision through the mandible, either in the midline (median) or slightly off-center (paramedian), to gain access to the oral cavity and the lesion.
- Advantages:
- Provides excellent access to deep-seated lesions and allows for adequate resection with clear margins.
- Facilitates reconstruction if needed.
- Limitations: Higher morbidity associated with mandibular manipulation, including potential complications such as nonunion or malocclusion.
Types of Hemorrhage
Hemorrhage, or excessive bleeding, can occur during and after surgical procedures. Understanding the different types of hemorrhage is crucial for effective management and prevention of complications. The three main types of hemorrhage are primary, reactionary, and secondary hemorrhage.
1. Primary Hemorrhage
- Definition: Primary hemorrhage refers to bleeding that occurs at the time of surgery.
- Causes:
- Injury to blood vessels during the surgical procedure.
- Inadequate hemostasis (control of bleeding) during the operation.
- Management:
- Immediate control of bleeding through direct pressure, cauterization, or ligation of blood vessels.
- Use of hemostatic agents or sutures to secure bleeding vessels.
- Clinical Significance: Prompt recognition and management of primary hemorrhage are essential to prevent significant blood loss and ensure patient safety during surgery.
2. Reactionary Hemorrhage
- Definition: Reactionary hemorrhage occurs within a few hours after surgery, typically when the initial vasoconstriction of damaged blood vessels subsides.
- Causes:
- The natural response of blood vessels to constrict after injury may initially control bleeding. However, as the vasoconstriction diminishes, previously damaged vessels may begin to bleed again.
- Movement or changes in position of the patient can also contribute to the reopening of previously clamped vessels.
- Management:
- Monitoring the patient closely in the immediate postoperative period for signs of bleeding.
- If reactionary hemorrhage occurs, surgical intervention may be necessary to identify and control the source of bleeding.
- Clinical Significance: Awareness of the potential for reactionary hemorrhage is important for postoperative care, as it can lead to complications if not addressed promptly.
3. Secondary Hemorrhage
- Definition: Secondary hemorrhage refers to bleeding that occurs up to 14 days postoperatively, often as a result of infection or necrosis of tissue.
- Causes:
- Infection at the surgical site can lead to tissue breakdown and erosion of blood vessels, resulting in bleeding.
- Sloughing of necrotic tissue may also expose blood vessels that were previously protected.
- Management:
- Careful monitoring for signs of infection, such as increased pain, swelling, or discharge from the surgical site.
- Surgical intervention may be required to control bleeding and address the underlying infection.
- Antibiotic therapy may be necessary to treat the infection and prevent further complications.
- Clinical Significance: Secondary hemorrhage can be a serious complication, as it may indicate underlying issues such as infection or inadequate healing. Early recognition and management are crucial to prevent significant blood loss and promote recovery.
Frenectomy- Overview and Techniques
A frenectomy is a surgical procedure that involves the removal of a frenum, which is a thin band of fibrous tissue that connects the lip or tongue to the underlying alveolar mucosa. This procedure is often performed to address issues related to abnormal frenal attachments that can cause functional or aesthetic problems.
Key Features of Frenal Attachment
- A frenum consists of a thin band of fibrous tissue and a few muscle fibers, covered by mucous membrane. It serves to anchor the lip or tongue to the underlying structures.
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Common Locations:
- Maxillary Midline Frenum: The most commonly encountered frenum, located between the central incisors in the upper jaw.
- Lingual Frenum: Found under the tongue; its attachment can vary in length and thickness among individuals.
- Maxillary and Mandibular Frena: These can also be present in the premolar and molar areas, potentially affecting oral function and hygiene.
Indications for Frenectomy
- Functional Issues: An overly tight or thick frenum can restrict movement of the lip or tongue, leading to difficulties in speech, eating, or oral hygiene.
- Aesthetic Concerns: Prominent frena can cause spacing issues between teeth or affect the appearance of the smile.
- Orthodontic Considerations: In some cases, frenectomy may be performed prior to orthodontic treatment to facilitate tooth movement and prevent relapse.
Surgical Techniques
-
Z-Plasty Procedure:
- Indication: Used when the frenum is broad and the vestibule (the space between the lip and the gums) is short.
- Technique: This method involves creating a Z-shaped incision that allows for the repositioning of the tissue, effectively lengthening the vestibule and improving the functional outcome.
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V-Y Incision:
- Indication: Employed for lengthening a localized area, particularly when the frenum is causing tension or restriction.
- Technique: A V-shaped incision is made, and the tissue is then sutured in a Y configuration, which helps to lengthen the frenum and improve mobility.
Postoperative Care
- Pain Management: Patients may experience discomfort following the procedure, which can be managed with analgesics.
- Oral Hygiene: Maintaining good oral hygiene is crucial to prevent infection at the surgical site.
Seddon’s Classification of Nerve Injuries
-
Neuropraxia:
- Definition: This is the mildest form of nerve injury, often caused by compression or mild trauma.
- Sunderland Classification: Type I (10).
- Nerve Sheath: Intact; the surrounding connective tissue remains undamaged.
- Axons: Intact; the nerve fibers are not severed.
- Wallerian Degeneration: None; there is no degeneration of the distal nerve segment.
- Conduction Failure: Transitory; there may be temporary loss of function, but it is reversible.
- Spontaneous Recovery: Complete recovery is expected.
- Time of Recovery: Typically within 4 weeks.
-
Axonotmesis:
- Definition: This injury involves damage to the axons while the nerve sheath remains intact. It is often caused by more severe trauma, such as crush injuries.
- Sunderland Classification: Type II (20), Type III (30), Type IV (40).
- Nerve Sheath: Intact; the connective tissue framework is preserved.
- Axons: Interrupted; the nerve fibers are damaged but the sheath allows for potential regeneration.
- Wallerian Degeneration: Yes, partial; degeneration occurs in the distal segment of the nerve.
- Conduction Failure: Prolonged; there is a longer-lasting loss of function.
- Spontaneous Recovery: Partial recovery is possible, depending on the extent of the injury.
- Time of Recovery: Recovery may take months.
-
Neurotmesis:
- Definition: This is the most severe type of nerve injury, where both the axons and the nerve sheath are disrupted. It often results from lacerations or severe trauma.
- Sunderland Classification: Type V (50).
- Nerve Sheath: Interrupted; the connective tissue is damaged, complicating regeneration.
- Axons: Interrupted; the nerve fibers are completely severed.
- Wallerian Degeneration: Yes, complete; degeneration occurs in both the proximal and distal segments of the nerve.
- Conduction Failure: Permanent; there is a lasting loss of function.
- Spontaneous Recovery: Poor to none; recovery is unlikely without surgical intervention.
- Time of Recovery: Recovery may begin by 3 months, if at all.
Maxillectomy
Maxillectomy is a surgical procedure involving the resection of the maxilla (upper jaw) and is typically performed to remove tumors, treat severe infections, or address other pathological conditions affecting the maxillary region. The procedure requires careful planning and execution to ensure adequate access, removal of the affected tissue, and preservation of surrounding structures for optimal functional and aesthetic outcomes.
Surgical Access and Incision
-
Weber-Fergusson Incision:
- The classic approach to access the maxilla is through the Weber-Fergusson incision. This incision provides good visibility and access to the maxillary region.
- Temporary Tarsorrhaphy: The eyelids are temporarily closed using tarsorrhaphy sutures to protect the eye during the procedure.
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Tattooing for Aesthetic Alignment:
- To achieve better cosmetic results, it is recommended to tattoo the vermilion border and other key points on both sides of the incision with methylene blue. These points serve as guides for alignment during closure.
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Incision Design:
- The incision typically splits the midline of the upper lip but can be modified for better cosmetic outcomes by incising along the philtral ridges and offsetting the incision at the vermilion border.
- The incision is turned 2 mm from the medial canthus of the eye. Intraorally, the incision continues through the gingival margin and connects with a horizontal incision at the depth of the labiobuccal vestibule, extending back to the maxillary tuberosity.
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Continuation of the Incision:
- From the maxillary tuberosity, the incision turns medially across the posterior edge of the hard palate and then turns 90 degrees anteriorly, several millimeters to the proximal side of the midline, crossing the gingival margin again if possible.
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Incision to Bone:
- The incision is carried down to the bone, except beneath the lower eyelid, where the orbicularis oculi muscle is preserved. The cheek flap is then reflected back to the tuberosity.
Surgical Procedure
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Extraction and Elevation:
- The central incisor on the involved side is extracted, and the gingival and palatal mucosa are elevated back to the midline.
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Deepening the Incision:
- The incision extending around the nose is deepened into the nasal cavity. The palatal bone is divided near the midline using a saw blade or bur.
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Separation of Bone:
- The basal bone is separated from the frontal process of the maxilla using an osteotome. The orbicularis oculi muscle is retracted superiorly, and the bone cut is extended across the maxilla, just below the infraorbital rim, into the zygoma.
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Maxillary Sinus:
- If the posterior wall of the maxillary sinus has not been invaded by the tumor, it is separated from the pterygoid plates using a pterygoid chisel.
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Specimen Removal:
- The entire specimen is removed by severing the remaining attachments with large curved scissors placed behind the maxilla.
Postoperative Considerations
- Wound Care: Proper care of the surgical site is essential to prevent infection and promote healing.
- Rehabilitation: Patients may require rehabilitation to address functional issues related to speech, swallowing, and facial aesthetics.
- Follow-Up: Regular follow-up appointments are necessary to monitor healing and assess for any complications or recurrence of disease.
Management of Septic Shock
Septic shock is a life-threatening condition characterized by severe infection leading to systemic inflammation, vasodilation, and impaired tissue perfusion. Effective management is crucial to improve outcomes and reduce mortality. The management of septic shock should be based on several key principles:
Key Principles of Management
-
Early and Effective Volume Replacement:
- Fluid Resuscitation: Initiate aggressive fluid resuscitation with crystalloids (e.g., normal saline or lactated Ringer's solution) to restore intravascular volume and improve circulation.
- Goal: Aim for a rapid infusion of 30 mL/kg of crystalloid fluids within the first 3 hours of recognition of septic shock.
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Restoration of Tissue Perfusion:
- Monitoring: Continuous monitoring of vital signs, urine output, and laboratory parameters to assess the effectiveness of resuscitation.
- Target Blood Pressure: In most patients, a systolic blood pressure of 90 to 100 mm Hg or a mean arterial pressure (MAP) of 70 to 75 mm Hg is considered acceptable.
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Adequate Oxygen Supply to Cells:
- Oxygen Delivery: Ensure adequate oxygen delivery to tissues by maintaining hemoglobin saturation (SaO2) above 95% and arterial oxygen tension (PaO2) above 60 mm Hg.
- Hematocrit: Maintain hematocrit levels above 30% to ensure sufficient oxygen-carrying capacity.
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Control of Infection:
- Antibiotic Therapy: Administer broad-spectrum antibiotics as soon as possible, ideally within the first hour of recognizing septic shock. Adjust based on culture results and sensitivity.
- Source Control: Identify and control the source of infection (e.g., drainage of abscesses, removal of infected devices).
Pharmacological Management
-
Vasopressor Therapy:
- Indication: If hypotension persists despite adequate fluid resuscitation, vasopressors are required to increase arterial pressure.
- First-Line Agents:
- Dopamine: Often the first choice due to its ability to maintain organ blood flow, particularly to the kidneys and mesenteric circulation. Typical dosing is 20 to 25 micrograms/kg/min.
- Noradrenaline (Norepinephrine): Should be added if hypotension persists despite dopamine administration. It is the preferred vasopressor for septic shock due to its potent vasoconstrictive properties.
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Cardiac Output and Myocardial Function:
- Dobutamine: If myocardial depression is suspected (e.g., low cardiac output despite adequate blood pressure), dobutamine can be added to improve cardiac output without significantly increasing arterial pressure. This helps restore oxygen delivery to tissues.
- Monitoring: Continuous monitoring of cardiac output and systemic vascular resistance is essential to assess the effectiveness of treatment.
Additional Considerations
- Supportive Care: Provide supportive care, including mechanical ventilation if necessary, and monitor for complications such as acute respiratory distress syndrome (ARDS) or acute kidney injury (AKI).
- Nutritional Support: Early enteral nutrition should be initiated as soon as feasible to support metabolic needs and improve outcomes.
- Reassessment: Regularly reassess the patient's hemodynamic status and adjust fluid and medication therapy accordingly.