NEET MDS Lessons
Oral and Maxillofacial Surgery
Upper Airway Components
- Nasal cavity: First line filtration, warming, humidification
- Oral cavity: Alternative route, larger diameter
- Pharynx: Nasopharynx, oropharynx, hypopharynx
- Larynx: Voice production, airway protection
- Trachea: Conduit to lower respiratory tract
Critical Anatomical Considerations
- Tongue: Largest soft tissue mass in oral cavity
- Epiglottis: Primary airway protection mechanism
- Vocal cords: Narrowest part of adult airway
- Cricothyroid membrane: Emergency surgical access point
- Pediatric differences: Proportionally larger tongue, higher larynx
- Osteomyelitis in mandible: Poor blood supply from single endosteal vessel.
- Sentinel lymph node: First node receiving lymphatic drainage from tumor.
- Carcinoma – in – situ: Dysplasia involving all epithelial layers, not beyond basal layer.
- Ulcers >2 weeks: Biopsy recommended, esp. with rolled borders.
- Selective neck dissection: Preferred for N0 neck in oral SCC.
- Radical neck dissection: Removes SAN, SCM, IJV, and lymphatics (regions I – V).
- Airway opening maneuver: Chin lift jaw thrust
- Initial fluid for trauma/burn resuscitation: Ringer’s lactate
- Loss of consciousness after facial trauma: Suspect acute epidural hematoma
- Retrobulbar hematoma relief: Lateral cantholysis
- Danger space: Between alar & prevertebral fascia
- Battle’s sign: Mastoid ecchymosis → middle cranial fossa fracture
- Tension pneumothorax: One – way valve mechanism
- Cushing’s phenomenon: Hypertension + bradycardia → ↑ ICP
- Urine output: Best indicator of cardiac output
- Normal urine output: 50 mL/hr
- Loss of consciousness: Occurs after >50% blood volume loss
Nasogastric Tube (Ryles Tube)
A nasogastric tube (NG tube), commonly referred to as a Ryles tube, is a medical device used for various purposes, primarily involving the stomach. It is a long, hollow tube made of polyvinyl chloride (PVC) with one blunt end and multiple openings along its length. The tube is designed to be inserted through the nostril, down the esophagus, and into the stomach.
Description and Insertion
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Structure: The NG tube has a blunt end that is inserted into the nostril, and it features multiple openings to allow for the passage of fluids and air. The open end of the tube is used for feeding or drainage.
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Insertion Technique:
- The tube is gently passed through one of the nostrils and advanced through the nasopharynx and into the esophagus.
- Care is taken to ensure that the tube follows the natural curvature of the nasal passages and esophagus.
- Once the tube is in place, its position must be confirmed before any feeds or medications are administered.
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Position Confirmation:
- To check the position of the tube, air is pushed into the tube using a syringe.
- The presence of air in the stomach is confirmed by auscultation with a stethoscope, listening for the characteristic "whoosh" sound of air entering the stomach.
- Only after confirming that the tube is correctly positioned in the stomach should feeding or medication administration begin.
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Securing the Tube: The tube is fixed to the nose using sticking plaster or adhesive tape to prevent displacement.
Uses of Nasogastric Tube
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Nutritional Support:
- Enteral Feeding: The primary use of a nasogastric
tube is to provide nutritional support to patients who are unable to
take oral feeds due to various reasons, such as:
- Neurological conditions (e.g., stroke, coma)
- Surgical procedures affecting the gastrointestinal tract
- Severe dysphagia (difficulty swallowing)
- Enteral Feeding: The primary use of a nasogastric
tube is to provide nutritional support to patients who are unable to
take oral feeds due to various reasons, such as:
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Gastric Lavage:
- Postoperative Care: NG tubes can be used for gastric lavage to flush out blood, fluids, or other contents from the stomach after surgery. This is particularly important in cases where there is a risk of aspiration or when the stomach needs to be emptied.
- Poisoning: In cases of poisoning or overdose, gastric lavage may be performed using an NG tube to remove toxic substances from the stomach. This procedure should be done promptly and under medical supervision.
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Decompression:
- Relieving Distension: The NG tube can also be used to decompress the stomach in cases of bowel obstruction or ileus, allowing for the removal of excess gas and fluid.
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Medication Administration:
- The tube can be used to administer medications directly into the stomach for patients who cannot take oral medications.
Considerations and Complications
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Patient Comfort: Insertion of the NG tube can be uncomfortable for patients, and proper technique should be used to minimize discomfort.
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Complications: Potential complications include:
- Nasal and esophageal irritation or injury
- Misplacement of the tube into the lungs, leading to aspiration
- Sinusitis or nasal ulceration with prolonged use
- Gastrointestinal complications, such as gastric erosion or ulceration
- Poorly differentiated tumors: Highest malignancy
- Argon – beam coagulation: Controls bleeding <3 mm vessels
- Cryosurgery: Liquid nitrogen ( – 196°C), CO₂/N₂O ( – 200 to – 900°C)
- PET imaging: Uses Fluorodeoxyglucose (FDG) → detects ↑ glucose uptake in malignancy
- Organ of Chievitz: Juxtaoral organ near internal pterygoid; may mimic perineural invasion
- NEO trauma: ↑ intercanthal distance
- Frontal bar fracture: ↑ interpupillary distance
- EDCP plate: For cases without tension band; provides compression
- Outer oblique hole: Rotational movement → superior border compression
- More difficult to apply than standard plates
Crocodile Tear Syndrome, also known as Bogorad syndrome, is characterized by involuntary tearing while eating, often resulting from facial nerve damage, such as that caused by Bell's palsy or trauma. Treatment typically involves botulinum toxin injections into the lacrimal glands to alleviate symptoms. ### Overview of Crocodile Tear Syndrome
Crocodile Tear Syndrome is a condition where individuals experience excessive tearing while eating or drinking. This phenomenon occurs due to misdirection of nerve fibers from the facial nerve, particularly affecting the lacrimal gland.
Causes
- Facial Nerve Injury: Damage to the facial nerve, especially proximal to the geniculate ganglion, can lead to abnormal nerve regeneration.
- Misdirection of Nerve Fibers: Instead of innervating the submandibular gland, the nerve fibers may mistakenly connect to the lacrimal gland via the greater petrosal nerve.
Symptoms
- Paroxysmal Lacrimation: Patients experience tearing during meals, which can be distressing and socially embarrassing.
- Associated Conditions: Often seen in individuals recovering from Bell's palsy or other facial nerve injuries.
Treatment Options
- Surgical Intervention: Division of the greater petrosal nerve can be performed to alleviate symptoms by preventing the misdirected signals to the lacrimal gland.
- Botulinum Toxin Injections: Administering botulinum toxin into the lacrimal glands can help reduce excessive tearing by temporarily paralyzing the gland.