NEET MDS Lessons
Oral and Maxillofacial Surgery
| Instrument | Use |
|---|---|
| Moons probe | Elevate mucoperiosteum |
| Hemostatic forceps | Control small vessel bleeding |
| Mouth props | Keep mouth open (metal/rubber) |
| Mouth gags | Used under GA (Doyen’s, Fergusson’s) |
| Heister’s jaw stretcher | For trismus |
| Curettes (Lucas) | Remove debris, cysts, tumors |
| Lister’s sinus forceps | Open abscess (Hilton’s method) |
| Rongeur forceps | Remove bone |
| Chisels | Unibeveled; bone removal |
Le Fort I Fracture
- A horizontal fracture that separates the maxilla from the nasal and zygomatic bones. It is also known as a "floating maxilla."
Signs and Symptoms:
- Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
- Disturbed Occlusion: Malocclusion due to displacement of the maxilla.
- Mobility of the Maxilla: The maxilla may move independently of the rest of the facial skeleton.
- Nasal Bleeding: Possible epistaxis due to injury to the nasal mucosa.
- CSF Rhinorrhea: If there is a breach in the dura mater, cerebrospinal fluid may leak from the nose.
Le Fort II Fracture
- A pyramidal fracture that involves the maxilla, nasal bones, and the zygomatic bones. It is characterized by a fracture line that extends from the nasal bridge to the maxilla and zygomatic arch.
Signs and Symptoms:
- Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
- Diplopia: Double vision due to involvement of the orbital floor and potential muscle entrapment.
- Enophthalmos: Posterior displacement of the eyeball within the orbit.
- Restriction of Globe Movements: Limited eye movement due to muscle entrapment.
- Disturbed Occlusion: Malocclusion due to displacement of the maxilla.
- Nasal Bleeding: Possible epistaxis.
- CSF Rhinorrhea: If the dura is torn, cerebrospinal fluid may leak from the nose.
Le Fort III Fracture
- A craniofacial disjunction fracture that involves the maxilla, zygomatic bones, and the orbits. It is characterized by a fracture line that separates the entire midface from the skull base.
Signs and Symptoms:
- Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
- Orbital Dystopia: Abnormal positioning of the orbits, often with an antimongoloid slant.
- Diplopia: Double vision due to muscle entrapment or damage.
- Enophthalmos: Posterior displacement of the eyeball.
- Restriction of Globe Movements: Limited eye movement due to muscle entrapment.
- Disturbed Occlusion: Significant malocclusion due to extensive displacement of facial structures.
- CSF Rhinorrhea: If there is a breach in the dura mater, cerebrospinal fluid may leak from the nose or ears (CSF otorrhea).
- Bleeding Over Mastoid Process (Battle’s Sign): Bruising behind the ear may indicate a skull base fracture.
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.
- Minimum platelet count for surgery: 75,000/cu mm
- Absolute contraindication: Platelets < 50,000/cu mm
- Blood unit volume: 450 mL
- PRBC effect: ↑ Hb by 1 g/dL, ↑ Hct by 3%
- Warfarin patient: Check INR & PT before extraction
- Normal PT: 11–14 seconds
Isotonic, Hypotonic, and Hypertonic Solutions
. Different types of solutions have distinct properties and effects on the body. Below is a detailed explanation of isotonic, hypotonic, and hypertonic solutions, with a focus on 5% dextrose in water, normal saline, Ringer's lactate, and mannitol.
1. 5% Dextrose in Water (D5W)
- Classification: Although 5% dextrose in water is initially considered an isotonic solution, it behaves differently once administered.
- Metabolism: The dextrose (glucose) in D5W is rapidly metabolized by the body, primarily for energy. As the glucose is utilized, the solution effectively becomes free water.
- Net Effect:
- After metabolism, the remaining solution is essentially hypotonic because it lacks solutes (electrolytes) and provides free water.
- This results in the expansion of both extracellular fluid (ECF) and intracellular fluid (ICF), but the net effect is a greater increase in intracellular fluid volume due to the hypotonic nature of the remaining fluid.
- Clinical Use: D5W is often used for hydration, to provide calories, and in situations where free water is needed, such as in patients with hypernatremia.
2. Normal Saline (0.9% Sodium Chloride)
- Classification: Normal saline is an isotonic solution.
- Composition: It contains 0.9% sodium chloride, which closely matches the osmolarity of blood plasma.
- Effect on Fluid Balance:
- When administered, normal saline expands the extracellular fluid volume without causing significant shifts in intracellular fluid.
- It is commonly used for fluid resuscitation, maintenance of hydration, and as a diluent for medications.
- Clinical Use: Normal saline is often used in various clinical scenarios, including surgery, trauma, and dehydration.
3. Ringer's Lactate (Lactated Ringer's Solution)
- Classification: Ringer's lactate is also an isotonic solution.
- Composition: It contains sodium, potassium, calcium, chloride, and lactate, which helps buffer the solution and provides electrolytes.
- Effect on Fluid Balance:
- Like normal saline, Ringer's lactate expands the extracellular fluid volume without causing significant shifts in intracellular fluid.
- The lactate component is metabolized to bicarbonate, which can help correct metabolic acidosis.
- Clinical Use: Ringer's lactate is commonly used in surgical patients, those with burns, and in cases of fluid resuscitation.
4. Mannitol
- Classification: Mannitol is classified as a hypertonic solution.
- Composition: It is a sugar alcohol that is not readily metabolized by the body.
- Effect on Fluid Balance:
- Mannitol draws water out of cells and into the extracellular space due to its hypertonic nature, leading to an increase in extracellular fluid volume.
- This osmotic effect can be beneficial in reducing cerebral edema and intraocular pressure.
- Clinical Use: Mannitol is often used in neurosurgery, for patients with traumatic brain injury, and in cases of acute kidney injury to promote diuresis.
USP Classification
- Ranges: 11-0 (finest) to #5 (heaviest)
- Common oral surgery sizes:
- 6-0, 5-0: Delicate procedures, facial surgery
- 4-0, 3-0: General oral surgery, soft tissue closure
- 2-0: Heavy tissue, areas requiring strong closure
Selection Criteria
- Tissue type: Delicate tissues require finer sutures
- Healing time: Longer healing requires stronger/slower-absorbing sutures
- Location: Visible areas need finer sutures for better cosmesis
- Patient factors: Age, healing capacity, immune status
Characteristics of Middle-Third Facial Fractures
Middle-third facial fractures, often referred to as "midfacial fractures," involve the central portion of the face, including the nasal bones, maxilla, and zygomatic arch. These fractures can result from various types of trauma, such as motor vehicle accidents, falls, or physical assaults. The following points highlight the key features and clinical implications of middle-third facial fractures:
1. Oedema of the Middle Third of the Face
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Rapid Development: Oedema (swelling) in the middle third of the face develops quickly after the injury, leading to a characteristic "balloon" appearance. This swelling is due to the accumulation of fluid in the soft tissues of the face.
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Absence of Deep Cervical Fascia: The unique anatomical structure of the middle third of the face contributes to this swelling. The absence of deep cervical fascia in this region allows for the rapid spread of fluid, resulting in pronounced oedema.
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Clinical Presentation: In the early stages following injury, patients with middle-third fractures often present with similar facial appearances due to the characteristic swelling. This can make diagnosis based solely on visual inspection challenging.
2. Lengthening of the Face
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Displacement of the Middle Third: The downward and backward displacement of the middle third of the facial skeleton can lead to an increase in the overall length of the face. This displacement forces the mandible to open, which can result in a change in occlusion, particularly in the molar region.
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Gagging of Occlusion: The altered position of the mandible can lead to a malocclusion, where the upper and lower teeth do not align properly. This can cause discomfort and difficulty in chewing or speaking.
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Delayed Recognition of Lengthening: The true increase in facial length may not be fully appreciated until the initial oedema subsides. As the swelling decreases, the changes in facial structure become more apparent.
3. Nasal Obstruction
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Blood Clots in the Nares: Following a middle-third fracture, the nares (nostrils) may become obstructed by blood clots, leading to nasal congestion. This can significantly impact the patient's ability to breathe through the nose.
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Mouth Breathing: Due to the obstruction, patients are often forced to breathe through their mouths, which can lead to additional complications, such as dry mouth and increased risk of respiratory infections.