NEET MDS Synopsis
TRACHEOSTOMY TUBES
Surgery
TYPES OF TRACHEOSTOMY TUBE
A tracheostomy tube may be metallic or nonmetallic
Metallic Tracheostomy Tube
Metallic tubes are formed from the alloy of silver, copper and phosphorus
Example Jackson’s Tracheostomy tube.
Has an inner and an outer tube.The inner tube is longer than the outer one so that secretions and crusts formed in it can be removed and the tube reinserted after cleaning without difficulty. However, they do not have a cuff and cannot produce an airtight seal.
Advantages of a double lumen tracheostomy tube are easy to remove,clean and replace inner cannula.
Inner cannula should be removed and cleaned as and when indicated for the first 3 days. Outer tube, unless blocked or displaced, should not be removed for 3-4 days to allow a track to be formed when tube placement will be easy.
Nonmetallic Tracheostomy Tube
Can be of cuffed or noncuffed variety, e.g. rubber and PVC tubes.
Cuffed Tracheostomy Tubes
Pediatric tubes do not have a cuff.
Cuffed tubes are used in situation where positive pressure ventilation is required, or when the airway is at risk from aspiration. (In unconscious patient or when patient is on respiration).
The cuff should be deflated every 2 hours for 5 mins to present pressure damage to the trachea.
Uncuffed Tracheostomy Tubes
It is suitable for a patient who has returned to the ward from a prolonged stay in intensive care and requires physiotherapy and suction via trachea.
This type of tube is not suitable for patients who are unable to swallow due to incompetent laryngeal reflexes, and aspiration of oral or gastric contents is likely to occur.
An uncuffed tube is advantageous in that it allows the patient to breathe around it in the event of the tube becoming blocked. Patients can also speak with an uncuffed tube.
Important
Nonmetallic Tracheostomy Tube - Cuffed tubes are used in situation where positive pressure ventilation is required, or when the airway is at risk from aspiration. (In unconscious patient or when patient is on respiration).
Metallic Tracheostomy Tube -Metallic tubes are formed from the alloy of silver, copper and phosphorus .
Example Jackson’s Tracheostomy tube.
Advantages of a double lumen tracheostomy tube are easy to remove,clean and replace inner cannula.
Parathyroid Hormone
Biochemistry
Parathyroid Hormone
Parathyroid hormone (PTH), parathormone or parathyrin, is secreted by the chief cells of the parathyroid glands.
It acts to increase the concentration of calcium (Ca2+) in the blood, whereas calcitonin (a hormone produced by the parafollicular cells of the thyroid gland) acts to decrease calcium concentration.
PTH acts to increase the concentration of calcium in the blood by acting upon the parathyroid hormone 1 receptor (high levels in bone and kidney) and the parathyroid hormone 2 receptor (high levels in the central nervous system, pancreas, testis, and placenta).
Effect of parathyroid hormone in regulation of serum calcium.
Bone -> PTH enhances the release of calcium from the large reservoir contained in the bones. Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly stimulated by PTH forming new osteoclasts, which ultimately enhances bone resorption.
Kidney -> PTH enhances active reabsorption of calcium and magnesium from distal tubules of kidney. As bone is degraded, both calcium and phosphate are released. It also decreases the reabsorption of phosphate, with a net loss in plasma phosphate concentration. When the calcium:phosphate ratio increases, more calcium is free in the circulation.
Intestine -> PTH enhances the absorption of calcium in the intestine by increasing the production of activated vitamin D. Vitamin D activation occurs in the kidney. PTH converts vitamin D to its active form (1,25-dihydroxy vitamin D). This activated form of vitamin D increases the absorption of calcium (as Ca2+ ions) by the intestine via calbindin.
Emergency conditions in Dental Clinics p2
Oral Medicine
Emergency conditions in Dental Clinics
Hypoadrenalism - Usually the patient is known to have Addison's disease or to be taking steroids long term and has forgotten to take the tablets.
Signs and symptoms
• Pallor
• Confusion
• Rapid weak pulse.
Treatment:
Give oxygen
Give 200 mg hydrocortisone sodium succinate by slow i.v. injection.
Give steroid replacement
Determining and managing underlying cause once the crisis over.
If required:
• Transfer to Emergeny hostpital
• Fluids and further hydrocortisone, both i.v.
Acute asthma - Exposure to antigen but precipitated by many factors including anxiety.
Signs and symptoms
• Persistent shortness of breath poorly relieved by bronchodilators
• Restlessness and exhaustion
• Tachycardia greater than 110 beats/min and low peak expiratory flow
• Respirations may be so shallow in severe cases that wheezing is absent.
Treatment
Excluded respiratory obstruction
Sit the patient up
Give oxygen
Salbutamol (Ventolin) via a nebuliser (2.5-5 mg of 1 mg/ml nebuliser solution) or via a large-volume spacer (two puffs of a metered dose inhaler 10-20 times: one puff every 30 seconds up to 10 puffs for a child)
Reassure and allow home if recovered.
• Bronchodilatation.
If Major Problem recommend to hospital Emergeny
• Hydrocortisone sodium succinate i.v.: adults 200 mg; child 100 mg
• Add ipratropium 0.5 mg to nebulised salbutamol
• Aminophylline slow i.v. injection of 250 mg in 10 ml over at least 20 minutes: monitor or keep finger on pulse during injection.
Caution in epilepsy: rapid injection of aminophylline may cause arrhythmias and convulsions.
Caution in patients already receiving theophylline: arrhythmias or convulsions may occur.
Anaphylactic shock
Signs and symptoms
• Paraesthesia, flushing and swelling of face, especially eyelids and lips (Fig. 13)
• generalised urticaria, especially hands and feet
• wheezing and difficulty in breathing
• rapid weak pulse.
These may develop over 15 to 30 minutes following the oral administration of a drug or rapidly over a few minutes following i.v. drug administration.
Treatment
Lay patient flat and raise feet
Give oxygen
Give 0.5 ml epinephrine (adrenaline) 1 mg/ml (1 in
1000) intramuscular
— 0.25 ml for 6-12 years
— 0.12 ml for 6 months to 6 years
repeated every 10 min until improvement.
Requires prompt energetic treatment of
• laryngeal oedema
• bronchospasm
• hypotension.
• Chlorphenamine (chlorpheniramine) 10 mg in 1 ml intramuscular or slow i.v. injection
• Hydrocortisone sodium succinate 200 mg by slow i.v. injection: valuable as action persists after that of adrenaline has worn off
• Fluids i.v. (colloids) infused rapidly if shock not responding quickly to adrenaline.
Stroke - Stroke results from either cerebral haemorrhage or cerebral ischaemia.
Signs and symptoms
• Confusion followed by signs and symptoms of focal brain damage
• Hemiplegia or quadriplegia
• Sensory loss
• Dysphasia
• Locked-in syndrome (aware, but unable to respond).
Treatment
Maintain and transfer for further investigation.
Benzodiazepine overdose - Overdose can result from a large or a fast dose of benzodiazepine or can occur in a sensitive patient.
Signs and symptoms
• Deeply sedated
• Severe respiratory depression.
Treatment
Flumazenil (Annexate) 200 mg over 15 seconds as 100 mg/ml i.v. followed by 100 mg every 1 minute up to maximum of 1 mg Maintain airway with head tilt/chin lift
Give oxygen.
Treatment
The action of the benzodiazepine is reversed with the specific antagonist.
Angina and myocardial infarction
Signs and symptoms
• Sudden onset of severe crushing pain across front of chest, which may radiate towards the shoulder and down the left arm or into the neck and jaw; pain from angina usually radiates down left arm
Skin pale and clammy
Shallow respirations
Nausea
Weak pulse and hypotension
If the pain not relieved by glyceryl trinitrate (GTN) then cause is myocardial infarction rather than angina.
First-line treatment of angina and myocardial infarction
Allow patient to rest in position that feels most comfortable:
• in presence of breathlessness this is likely to be the sitting position, whereas syncopal patients will want to lie flat
• often an intermediate position will be most appropriate.
Angina -
Angina results from reduced coronary artery lumen diameter because of atheromatous plaques
Myocardial infarction is usually the result of thrombosis in a coronary artery.
Angina is relieved by rest and nitrates:
• Glyceryl trinitrate spray 400 mg metered dose (sprayed on oral mucosa or under tongue and mouth then closed)
• Give oxygen
• Allow home if attack is mild and the patient recovers rapidly.
Myocardial infarction
If a myocardial infarction is suspected:
• give oxygen
• aspirin tablet 300 mg chewed.
• Pain control
• Vasodilatation of blood vessels to reduce load on heart.
Further management for severe angina or myocardial infarction
• Transfer to Emergency
• Diamorphine 5 mg (2.5 mg in older people) by slow i.v. injection (1 mg/min)
• Early thrombolytic therapy reduces mortality.
Cardiac arrest
• Most cardiac arrests result from arrhythmias associated with acute myocardial infarction or chronic ischaemic heart disease
• The heart arrests in one of three rhythms
— VF (ventricular fibrillation) or pulseless VT (ventricular tachycardia)
— asystole
— PEA (pulseless electrical activity) or EMD (electromechanical dissociation).
Signs and symptoms
• Unconscious
• No breathing
• Absent carotid pulse.
Treatment
• Circulation failure for 4 minutes, or less if the patient is already hypoxaemic, will lead to irreversible brain damage
• Institute early basic life support as holding procedure until early advanced life support is available.
• Transfer to Emergency
• Advanced life support.
Advanced life support for cardiac arrest
Advanced airway management techniques and specific treatment of the underlying cause of cardiac arrest constitute advanced life support (ALS).
INFARCTION
General Pathology
INFARCTION
Definition : a localized area of ischaemic necrosis in an organ infarcts may be:
Pale :as in
→ Arterial obstruction.
→ solid organs.
Red as in
→ Venous occlusion
→ Loose tissue.
Morphology
Gross: infarcts are usually wedge shaped the apex towards the occluded vessel They are
separated from the surrounding tissue by an hyperemic inflammatory zone
Microscopic:
- An area of coagulative necrosis with a rim of congested vessels and acute inflammatory infiltration of the tissue .
- The polymorphs ale later replaced by mononuclear cells and granulation tissue.
- With time, scar tissue replaces necrosed tissue.
Keratoses (Horny Growth)
General Pathology
Keratoses (Horny Growth)
1. Seborrheic keratosis is a common benign epidermal tumor composed of basaloid (basal cell-like) cells with increased pigmentation that produce a raised, pigmented, "stuck-on" appearance on the skin of middle-aged individuals.
- they can easily be scraped from the skin's surface.
- frequently enlarge of multiply following hormonal therapy.
- sudden appearance of large numbers of Seborrheic keratosis is a possible indication of a malignancy of the gastrointestinal tract (Leser-Trelat sign).
2. An actinic keratosis is a pre-malignant skin lesion induced by ultraviolet light damage.
- sun exposed areas.
- parakeratosis and atypia (dysplasia) of the keratinocytes.
- solar damage to underlying elastic and collagen tissue (solar elastosis).
- may progress to squamous carcinoma in situ (Bowen's disease) or invasive cancer.
3. A keratoacanthoma is characterized by the rapid growth of a crateriform lesion in 3 to 6
weeks usually on the face or upper extremity.
- it eventually regresses and involutes with scarring.
- commonly confused with a well-differentiated squamous cell carcinoma.
Osteomyelitis of the Jaw (OML)
Oral and Maxillofacial SurgeryOsteomyelitis of the Jaw (OML)
Osteomyelitis of the jaw (OML) is a serious infection of the bone that can
lead to significant morbidity if not properly diagnosed and treated.
Understanding the etiology and microbiological profile of OML is crucial for
effective management. Here’s a detailed overview based on the information
provided.
Historical Perspective on Etiology
Traditional View: In the past, the etiology of OML was
primarily associated with skin surface bacteria, particularly Staphylococcus
aureus. Other bacteria, such as Staphylococcus epidermidis and
hemolytic streptococci, were also implicated.
Reevaluation: Recent findings indicate that S.
aureus is not the primary pathogen in cases of OML affecting
tooth-bearing bone. This shift in understanding highlights the complexity of
the microbial landscape in jaw infections.
Microbiological Profile
Common Pathogens:
Aerobic Streptococci:
α-Hemolytic Streptococci: Particularly Streptococcus
viridans, which are part of the normal oral flora and can
become pathogenic under certain conditions.
Anaerobic Streptococci: These bacteria thrive in
low-oxygen environments and are significant contributors to OML.
Other Anaerobes:
Peptostreptococcus: A genus of anaerobic
bacteria commonly found in the oral cavity.
Fusobacterium: Another group of anaerobic
bacteria that can be involved in polymicrobial infections.
Bacteroides: These bacteria are also part of
the normal flora but can cause infections when the balance is
disrupted.
Additional Organisms:
Gram-Negative Organisms:
Klebsiella, Pseudomonas, and Proteus species
may also be isolated in some cases, particularly in chronic or
complicated infections.
Specific Pathogens:
Mycobacterium tuberculosis: Can cause
osteomyelitis in the jaw, particularly in immunocompromised
individuals.
Treponema pallidum: The causative agent of
syphilis, which can lead to specific forms of osteomyelitis.
Actinomyces species: Known for causing
actinomycosis, these bacteria can also be involved in jaw
infections.
Polymicrobial Nature of OML
Polymicrobial Disease: Established acute OML is
typically a polymicrobial infection, meaning it involves multiple types of
bacteria. The common bacterial constituents include:
Streptococci (both aerobic and anaerobic)
Bacteroides
Peptostreptococci
Fusobacteria
Other opportunistic bacteria that may contribute to the infection.
Clinical Implications
Sinus Tract Cultures: Cultures obtained from sinus
tracts in the jaw may often be misleading. They can be contaminated with
skin flora, such as Staphylococcus species, which do not accurately
represent the pathogens responsible for the underlying osteomyelitis.
Diagnosis and Treatment: Understanding the
polymicrobial nature of OML is essential for effective diagnosis and
treatment. Empirical antibiotic therapy should consider the range of
potential pathogens, and cultures should be interpreted with caution.
Meperidine
Pharmacology
Meperidine (Demerol)
Meperidine is a phenylpiperidine and has a number of congeners. It is mostly effective in the CNS and bowel
Produces analgesia, sedation, euphoria and respiratory depression.
Less potent than morphine, 80-100 mg meperidine equals 10 mg morphine.
Shorter duration of action than morphine (2-4 hrs).
Meperidine has greater excitatory activity than does morphine and toxicity may lead to convulsions.
Meperidine appears to have some atropine-like activity.
Does not constrict the pupils to the same extent as morphine.
Does not cause as much constipation as morphine.
Spasmogenic effect on GI and biliary tract smooth muscle is less pronounced than that produced by morphine.
Not an effective antitussive agent.
In contrast to morphine, meperidine increases the force of oxytocin-induced contractions of the uterus.
Often the drug of choice during delivery due to its lack of inhibitory effect on uterine contractions and its relatively short duration of action.
It has serotonergic activity when combined with monoamine oxidase inhibitors, which can produce serotonin toxicity (clonus, hyperreflexia, hyperthermia, and agitation)
Nasogastric Tube (Ryles Tube)
Oral and Maxillofacial SurgeryNasogastric 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
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.
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.
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.
Securing the Tube: The tube is fixed to the nose using
sticking plaster or adhesive tape to prevent displacement.
Uses of Nasogastric Tube
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)
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.
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.
Medication Administration:
The tube can be used to administer medications directly into the
stomach for patients who cannot take oral medications.
Considerations and Complications
Patient Comfort: Insertion of the NG tube can be
uncomfortable for patients, and proper technique should be used to minimize
discomfort.
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