NEET MDS Lessons
General Surgery
Cardiovascular Effects of Sevoflurane, Halothane, and Isoflurane
- Sevoflurane:
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Maintains cardiac index and heart rate effectively.
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Exhibits less hypotensive and negative inotropic effects compared to halothane.
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Cardiac output is greater than that observed with halothane.
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Recovery from sevoflurane anesthesia is smooth and comparable to isoflurane, with a shorter time to standing than halothane.
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- Halothane:
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Causes significant decreases in mean arterial pressure, ejection fraction, and cardiac index.
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Heart rate remains at baseline levels, but overall cardiovascular function is depressed.
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Recovery from halothane is less favorable compared to sevoflurane and isoflurane.
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- Isoflurane:
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Preserves cardiac index and ejection fraction better than halothane.
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Increases heart rate while having less suppression of mean arterial pressure compared to halothane.
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Cardiac output during isoflurane anesthesia is similar to that of sevoflurane, indicating a favorable cardiovascular profile.
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Inflammation is the respone of the body to an irritant.
Stages of Inflammation
1. General: Temperature Raised. In severe cases bacteremia or septicemia ,rigors may occur.
2. Local: classical signs of inflammation are due to hyperemia and inflammation exudate
i) Heat: inflammed area feels warmer than the surrounding tissues.
ii) Redness
iii) Tenderness: Due to pressure of exudate on the surrounding nerves If the exudate is under tension, e.g. a furuncle (boil) of the ear, pain is severe.
iv) swelling
v) Loss of function.
The termination of Inflammation
This may be by:1. Resolution 2. Suppuration 3. Ulceration 4. Ganangren s. Fibrosis
Management
i. Increase the patients resistance., Rest, Relief of pain by analgesics, Diet: High protein and high calorie diet with vitamins, Antibiotics, Prevent further contamination of wound.
Surgical measures
1. Excision: If possible as in appendicectomy.
2. Incision and drainage: If an abscess forms.
Neuromuscular Blockers in Cardiac Anesthesia
In patient on β-blockers, the choice of neuromuscular blockers (NMBs) is critical due to their potential cardiovascular effects. Here’s a detailed analysis of the implications of using fentanyl and various NMBs, particularly focusing on vecuronium and its effects.
Key Points on Fentanyl and β-Blockers
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Fentanyl:
- Fentanyl is an opioid analgesic that can cause bradycardia due to its vagolytic activity. While it has minimal hemodynamic effects, the bradycardia it induces can be problematic, especially in patients already on β-blockers, which reduce heart rate and blood pressure.
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β-Blockers:
- These medications reduce heart rate and blood pressure, which can compound the bradycardic effects of fentanyl. Therefore, careful consideration must be given to the choice of additional medications that may further depress cardiac function.
Vecuronium
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Effects:
- Vecuronium is a non-depolarizing neuromuscular blocker that has minimal cardiovascular side effects when used alone. However, it can potentiate decreases in heart rate and cardiac index when administered after fentanyl.
- The absence of positive chronotropic effects (unlike pancuronium) means that vecuronium does not counteract the bradycardia induced by fentanyl, leading to a higher risk of significant bradycardia and hypotension.
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Vagal Tone:
- Vecuronium may enhance vagal tone, further predisposing patients to bradycardia. This is particularly concerning in patients on β-blockers, as the combination can lead to compounded cardiac depression.
Comparison with Other Neuromuscular Blockers
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Pancuronium:
- Vagolytic Action: Pancuronium has vagolytic properties that can help attenuate bradycardia and support blood pressure. It is often preferred in cardiac anesthesia for its more favorable hemodynamic profile compared to vecuronium.
- Tachycardia: While it can induce tachycardia, this effect may be mitigated in patients on β-blockers, which can blunt the tachycardic response.
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Atracurium:
- Histamine Release: Atracurium can release histamine, leading to hemodynamic changes such as increased heart rate and decreased blood pressure. These effects can be minimized by slow administration of small doses.
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Rocuronium:
- Minimal Hemodynamic Effects: Rocuronium is generally associated with a lack of significant cardiovascular side effects, although occasional increases in heart rate have been noted.
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Cis-Atracurium:
- Cardiovascular Stability: Cis-atracurium does not have cardiovascular effects and does not release histamine, making it a safer option in terms of hemodynamic stability.
An ulcer is a break in the continuity of the skin or the mucous membrane.
Mode of onset: Traumatic ulcers heal when the traumatic agent is removed., If it persists it becomes chronic as in the case of dental ulcer of the tongue. Ulcers may develop spontaneously as in the case of gumma (syphilitic ulcer). It may develop with varicose veins called varicose ulcer, which develops in the lower third of the leg.
Sometimes a malignant ulcer develops in a scar called Marjolin’s ulcer. Special features are:
No pain - as there are no nerves. It does not spread - as there is scar tissue. No metastases - as there are no lymphatics Treatment:- Wide excision.
Classification of Ulcer
A) Pathologically
I. Non-specific ulcers:
a. Due to infected wound after trauma, that is physical or chemical agents.
b. Due to local infection example dental ulcer, pressure sore
Specific ulcers: Caused by specific infection
a. Syphilitic ulcers (Hunterian chancre)
b. Tubercular ulcers, actinomycosis
Trophic ulcer:- Caused by two factors:
Diminished nutrition due to inadequate blood supply to the tissues
Eg. Ulcers in Buerger’s Disease, Artherosclerosis
b. Diminished or absence of sensation of the skin leading to perforating ulcer of the foot
iv. Malignant ulcer: Due to squamous cell carcinoma, rodent ulcers and melanoma.
B) Clinical classification of ulcers
1. Acute Ulcer: The edge is inflamed oedematous and painful with slough in the floor and n o granulation tissue. Profuse purulent Discgarge seen
2. Healing ulcers: edge sloping with bluish margin The floor is covered with a red, healthy granulation tissue.
3. Chronic or callous ulcer (non- healing) There is no tendency to heal by itself, the base is jndurated unhealthy granulation tissue is present in the floor The edge is rounded and thickened.
Chronic ulcer occur due to:
Chronic infection , Defective circulation , Foreign body, Persistent local oedema , Malignancy , Diabetes , Malnutrition (loss of proteins), Gout
Specific Ulcers
Tubeculous Ulcer
Edge Undermined, floor contains granulation tissue a watery discharge is present. Caseous material is found in the floor of the ulcer. It usually occurs in tubercular lymphadenitis in the neck, axilla or groin.
Syphilitic Ulcer
a) Huntarian Chancre or primary sore or hard chancre: usuaIly occurs over the genitalia especially on penis. Occurs in the primary stage of syphilis Ulcer is round or oval, it is hard,indurated, elevated and painless It feels like a button, discharges serum containing spirochetes (cork screw) which is highly infective.
b) In the Secondary stage mucous patches and condylomata occurs The ulcers are shallow white patches, of sodden thickness which occur in the mouth and tongue. Condyloma are hypertrophied epithelium with serous discharge occurring in mucocutaneous junction around the anus. The regional lymphnod (inguinal transverse chain) are enlarged.
c) In tertiary stage of syphilis gummatous ulcers occur They have a punched out edge and wash Ieather floor. They occur on the subcutaneous bones like sternum and tibia. They are painless and refuse to heal.
Soft Sore (chanchroid)
They are painful muitiple ulcers, with copious discharge. They are caused by Bacillus Ducrey lncubation time is 3 to 4 days. located on glans penis and prepuce is due to venereal infection. They are associated with enlarged called bilateral inguinal lymphnodes
Tropical ulcer:
a) Oriental Sore - due to L. Tropica (lieshmaniasis)
b) Ulcers and sinuses are due to guinea worm abscess
c) Histoplasmosis with multiple ulcers on the tibia.
d) Chronic ulcers due to yaws
e) Amoebic ulcers occur in colon_and rectum , flask shaped ulcers , undermined edge , caused by Entamoeba Histolytica
Varicose Ulcer:
Associated with varicose veins. Occurs on the inner aspect of the lower third of leg , chronic ulcer The surrounding area is pigmented and eczema is present. The sore is longitudinally oval It does not penetrate the deep fascia and is painless The base is adherent to the periosteum of the tibia
Rodent ulcer
Usually Occurs on the face above a line joining the lobule of the ear to the angle of the mouth. Usually occurs at the inner canthous of the eye . Edge is raised and rolled, Erodes the deeper structures and the bone, the lyrnph nodes are not involved.
Treatment: If small wide excision is done with skin grafting, If large, radiotherapy is given.
Malignant Ulcer
Occurs due to chronic irritation as in the case of malignant ulcer of the tongue. The edge is everted. The floor is covered with slough and tumor tissue The regional lymph nodes are hard.
Initially mobile later becomes hard
Treatment: Wide excision is done.
Marjolin ulcer: Malignant Ulcer occurring on scar of Burns
Walsham’s Forceps
Walsham’s forceps are specialized surgical instruments used primarily in the manipulation and reduction of fractured nasal fragments. They are particularly useful in the management of nasal fractures, allowing for precise adjustment and stabilization of the bone fragments during the reduction process.
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Design:
- Curved Blades: Walsham’s forceps feature two curved blades—one padded and one unpadded. The curvature of the blades allows for better access and manipulation of the nasal structures.
- Padded Blade: The padded blade is designed to provide a gentle grip on the external surface of the nasal bone and surrounding tissues, minimizing trauma during manipulation.
- Unpadded Blade: The unpadded blade is inserted into the nostril and is used to secure the internal aspect of the nasal bone and associated fragments.
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Usage:
- Insertion: The unpadded blade is carefully passed up the nostril to reach the fractured nasal bone and the associated fragment of the frontal process of the maxilla.
- Securing Fragments: Once in position, the nasal bone and the associated fragment are secured between the padded blade externally and the unpadded blade internally.
- Manipulation: The surgeon can then manipulate the fragments into their correct anatomical position, ensuring proper alignment and stabilization.
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Indications:
- Walsham’s forceps are indicated for use in cases of nasal fractures, particularly when there is displacement of the nasal bones or associated structures. They are commonly used in both emergency and elective settings for nasal fracture management.
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Advantages:
- Precision: The design of the forceps allows for precise manipulation of the nasal fragments, which is crucial for achieving optimal alignment and aesthetic outcomes.
- Minimized Trauma: The padded blade helps to reduce trauma to the surrounding soft tissues, which can be a concern during the reduction of nasal fractures.
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Postoperative Considerations:
- After manipulation and reduction of the nasal fragments, appropriate postoperative care is essential to monitor for complications such as swelling, infection, or malunion. Follow-up appointments may be necessary to assess healing and ensure that the nasal structure remains stable.
Tracheostomy
Tracheostomy is a surgical procedure that involves creating an opening in the trachea (windpipe) to facilitate breathing. This procedure is typically performed when there is a need for prolonged airway access, especially in cases where the upper airway is obstructed or compromised. The incision is usually made between the 2nd and 4th tracheal rings, as entry through the 1st ring can lead to complications such as tracheal stenosis.
Indications
Tracheostomy may be indicated in various clinical scenarios, including:
- Acute Upper Airway Obstruction: Conditions such as severe allergic reactions, infections (e.g., epiglottitis), or trauma that obstruct the airway.
- Major Surgery: Procedures involving the mouth, pharynx, or larynx that may compromise the airway.
- Prolonged Mechanical Ventilation: Patients requiring artificial ventilation for an extended period, such as those with respiratory failure.
- Unconscious Patients: Situations involving head injuries, tetanus, or bulbar poliomyelitis where airway protection is necessary.
Procedure
Technique
- Incision: A horizontal incision is made in the skin over the trachea, typically between the 2nd and 4th tracheal rings.
- Dissection: The subcutaneous tissue and muscles are dissected to expose the trachea.
- Tracheal Entry: An incision is made in the trachea, and a tracheostomy tube is inserted to maintain the airway.
Complications of Tracheostomy
Tracheostomy can be associated with several complications, which can be categorized into intraoperative, early postoperative, and late postoperative complications.
1. Intraoperative Complications
- Hemorrhage: Bleeding can occur during the procedure, particularly if major blood vessels are inadvertently injured.
- Injury to Paratracheal Structures:
- Carotid Artery: Injury can lead to significant hemorrhage and potential airway compromise.
- Recurrent Laryngeal Nerve: Damage can result in vocal cord paralysis and hoarseness.
- Esophagus: Injury can lead to tracheoesophageal fistula formation.
- Trachea: Improper technique can cause tracheal injury.
2. Early Postoperative Complications
- Apnea: Temporary cessation of breathing may occur, especially in patients with pre-existing respiratory issues.
- Hemorrhage: Postoperative bleeding can occur, requiring surgical intervention.
- Subcutaneous Emphysema: Air can escape into the subcutaneous tissue, leading to swelling and discomfort.
- Pneumomediastinum and Pneumothorax: Air can enter the mediastinum or pleural space, leading to respiratory distress.
- Infection: Risk of infection at the incision site or within the tracheostomy tube.
3. Late Postoperative Complications
- Difficult Decannulation: Challenges in removing the tracheostomy tube due to airway swelling or other factors.
- Tracheocutaneous Fistula: An abnormal connection between the trachea and the skin, which may require surgical repair.
- Tracheoesophageal Fistula: An abnormal connection between the trachea and esophagus, leading to aspiration and feeding difficulties.
- Tracheoinnominate Arterial Fistula: A rare but life-threatening complication where the trachea erodes into the innominate artery, resulting in severe hemorrhage.
- Tracheal Stenosis: Narrowing of the trachea due to scar tissue formation, which can lead to breathing difficulties.
Types of Head Injury
1. Extradural Hematoma (EDH)
Overview
- Demographics: Most common in young male patients.
- Association: Always associated with skull fractures.
- Injured Vessel: Middle meningeal artery.
- Common Site of Injury: Temporal bone at the pterion (the thinnest part of the skull), which overlies the middle meningeal artery.
- Location of Hematoma: Between the bone and the dura mater.
Other Common Sites
- Frontal fossa
- Posterior fossa
- May occur following disruption of major dural venous sinus.
Classical Presentation
- Initial Injury: Followed by a lucid interval where the patient may only complain of a headache.
- Deterioration: After minutes to hours, rapid
deterioration occurs, leading to:
- Contralateral hemiparesis
- Reduced consciousness level
- Ipsilateral pupillary dilatation (due to herniation)
Imaging
- CT Scan: Shows a lentiform (lens-shaped or biconvex) hyperdense lesion between the brain and skull.
Treatment
- Surgical Intervention: Immediate surgical evacuation via craniotomy.
- Mortality Rate: Overall mortality is 18% for all cases of EDH, but only 2% for isolated EDH.
2. Acute Subdural Hematoma (ASDH)
Overview
- Location: Accumulates in the space between the dura and arachnoid.
- Injury Mechanism: Associated with cortical vessel disruption and brain laceration.
- Primary Brain Injury: Often associated with primary brain injury.
Presentation
- Consciousness: Impaired consciousness from the time of impact.
Imaging
- CT Scan: Appears hyperdense, with hematoma spreading diffusely and having a concavo-convex appearance.
Treatment
- Surgical Intervention: Evacuation via craniotomy.
- Mortality Rate: Approximately 40%.
3. Chronic Subdural Hematoma (CSDH)
Overview
- Demographics: Most common in patients on anticoagulants and antiplatelet agents.
- History: Often follows a minor head injury weeks to months prior.
- Pathology: Due to the tear of bridging veins leading to ASDH, which is clinically silent. As the hematoma breaks down, it increases in volume, causing mass effect on the underlying brain.
Clinical Features
- Symptoms may include:
- Headache
- Cognitive decline
- Focal neurological deficits (FND)
- Seizures
- Important to exclude endocrine, hypoxic, and metabolic causes in this group.
Imaging
- CT Scan Appearance:
- Acute blood (0–10 days): Hyperdense
- Subacute blood (10 days to 2 weeks): Isodense
- Chronic (> 2 weeks): Hypodense
Treatment
- Surgical Intervention: Bur hole evacuation rather than craniotomy.
- Anesthesia: Elderly patients can often undergo surgery under local anesthesia, despite comorbidities.
4. Subarachnoid Hemorrhage (SAH)
Overview
- Causes: Most commonly due to aneurysms for spontaneous SAH, but trauma is the most common cause overall.
- Management: Conservative treatment is often employed for trauma cases.
5. Cerebral Contusions
Overview
- Definition: Bruising of the brain tissue due to trauma.
- Mechanism: Often occurs at the site of impact (coup) and the opposite side (contrecoup).
- Symptoms: Can range from mild confusion to severe neurological deficits depending on the extent of the injury.
Imaging
- CT Scan: May show areas of low attenuation (hypodense) or high attenuation (hyperdense) depending on the age of the contusion.
Treatment
- Management: Depends on the severity and associated injuries; may require surgical intervention if there is significant mass effect.