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

• 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.

• 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

• 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.

• 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

1. 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.

2. 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.

3. 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.

4. 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.

1 Cellulitis: a non-suppurative inflammation of subcutaneous tissue, extending along connective tissue planes and across intercellular spaces.

Spreading inflammation in the tissue planes is called cellulitis. There is wide spread swelling, redness and pain without definite localization.

Caused by Streptococcus pyogenes.. If general condition of the patient is undermined, as in diabetes, cellulitis spreads rapidly and leads to Septicemia (infection in the blood).Redness, itching and stiffness is present in the site of inoculation (where the bacteria enter the skin), local Gangrene (death of the tissue) may occur. The appearance of skin creases or wrinkles, indicates resolution (healing).

Treatment

1. Rest , Appropriate antibiotics.

Cellulitis of the neck: Is a complication of wounds tonsillitis or mastoiditis Ludwig’s angina is the term applied to sub-maxillary cellulitis. The two dangers of cervical cellulitis are:

1. Oedema of glottis - with possible asphyxia (respiratory obstructon )

2. Mediastinitis - In ludwig’s angina the floor of the mouth become oedematous. The tongue can be seen displaced, turned upwards by swelling and oedema. The patient is unable to close the mouth owing to oedema of the tongue and the floor of the mouth. This can also CCC when the tongue is bitten by a wasp.

Ludwig’s angina: Ludwig - characterized by a brawny (non pitting) swelling of the sub-mandibular region, corn with inflammatory oedema of the mouth. It is the combined cervical and intrabuccal signs that constitute the characteristic feature of the lesion. The cause of the condition is virulent, usually streptococcal infection of the cellular tissue surrounding the sub-mandibular salivary gland.

Clinical features

 The swollen tongue is pushed towards the palate and forwards through the open mouth, while the cellulitis extends down the neck.

The most dangerous plane, is deep to the deep fascia.

Ludwig’s angina is an infection of closed fascial space and if .untreated, the inflammatory exudate often passes via, the tunnel occupied by stylohyhoid to the submucosa of glottis, in which event the patient is in immediate danger of death from oedema of the glottis.

Treatment

1. antibiotics on Early Diagnosis

2. In cases where the swelling, both cervical and intrabuccal, does not subside rapidly with such treatment, a curved incision, beneath the jaw is made and this decompresses the closed fascial space. The incision is deepened and after displacing the superficial lobe of the sub-mandibular salivary gland, the mylohyoid muscle are divided. This decompresses the closed fascjal space referred to. The wound is lightly sutured and drained. The operation can be conducted with greatest safety under local anaesthesia.

Bacteraemia and  Septicemia

Bacteraemia and septicaemia means the organisms are present in the blood. Clinical features are those of severe infection and shock: , Pyrexia is intermittent , Rigors ,  Jaundice is due to liver damage,  Acute renal failure may occur , Peripheral circulatory failure,  lntravascular coagulation indicates a fatal outcome

 causative focus found and treated surgically .g., Appendicetomy in perforated appendix

2. Blood culture taken

3. Broad spectrum antibiotic is given

4. Blood transfusion is given.

5. Injection hydrocortisone is given.

Pyaemia

Pyaemia is due to infected emboli circulating in blood stream. Pyaemia is characterized by: -

1. Rigors

2. Intermittent fever

3. Formation of abscess in vital organs like heart or brain.

Treatment

1. Is to prevent emboli reaching the blood stream

2. Broad spectrum antibiotic is given.

3. Abscess are incised and drained

If not treated portal pyaemia with multiple abscesses in liver occur, which is a dangerous condition.

Acute Abscess :  An abscess a collection of pus.

Bacteria which cause pus formation is called pyogenic organisms. Bacteria reach the infected area by:

1. Direct route: eg. Penetrating wound

Local extension: From adjacent focus of infection

2 Lymphatics

4. Blood stream

Pyogenic membrane surrounds the abscess and is infiltration with (leukocytes and bacteria.

Pus: Pus contains dead leukocytes and bacteria. It reaches the surface of the body or is discharged into a hollow viscous.

Symptoms: patient feels ill., Throbbing pain is characteristic of suppuration. Pain becomes more severe in the dependent position. E.g. infected finger,

Classical signs

Temperature is elevated , Rigors, inflammation

Fluctuation: Present in the later stages, and reveals the presence of pus. Prevention

1. An abscess can sometimes be aborted by antibiotics in the early stage.,. Rest,  Elevation of the affected part.

Treatment

Is incision and drainage of abscess

Hilton’s method of opening an abscess:

It is used where important anatomical structures like the blood vessels and nerves are preesnt, as in the neck, axilla and groin. The skin and superficial fascia is incised. A sinus forceps is thrust into the abscess  cavity. The blades are opened and the pus is drained. A gloved finger is introduced and loculi are broken. A ribbon gauze is lightly packed and antibiotics are given. This is done under surface anaesthesia i.e., ethyl chloride spray.

Antibioma

 If antibiotic is given the pus in the abscess frequently becomes sterile and a large brawny edematous swelling remains which takes many weeks to resolve.

Treatment: explore the mass with a wide-bore aspirating needle

 Most antibiornas are due to late, inadequate, and ineffective antibiotics.

CANCRUM ORIS

Is an infective gangrene of cheek and lip.

may occur as a complication of kala azar, enteric fever and  children with poor oral hygiene.

The lesion starts as an acute inflammatory patch on oral mucosa which is seen ulcerated.

The affected part of the cheek or the lip gradually becomes gangrenous.

Focal vascular thrombosis and sepesis occur.

When slough separates, a part of the cheek or lip sloughs out to form a buccal fistula with ugly deformity. The adjacent jaw may be infected too.

Various organisms are found - specially Fusiform bacillus and_Borrellia vincenti.

The foetid odour, gangrenous patch of cheek or lip, purulent discharge from the mouth, fever and toxaemia are the characteristic features. The patient is unable to open the mouth properly.

Treatment

1. Antibiotics, multivitamins and repeated mouth washes

2 Neostibamine in kala-azar. Sequestrectomy in chronic osteomyelitis of the mandible.

4. Plastic reconstruction of the lip or cheek for unsightly deformity undertaken.

CARBUNCLE

Is an infective gangrene of the subcutaneous tissue. It is due to staphylococcal aureus infection. It is uncommon before the age of 40. Males are the usual sufferers. Diabetes may be present. It often occurs on the nape of the neck.

Clinical features

Subcutaneous tissue becomes painful and indurated. Ove skin is red. Unless treated promptly, extension will occur and late softening. The skin gives way and thick pus and slough are discharged.

Usually, there is one central large slough, surrounded by smaller areas of necrosis. Infection extends widely and fresh openings appear

Treatment

1. Many carbuncles are aborted, if penicillin is used adequately in the early stage.

2. Local treatment consists of hygroscopic dressings being given ie. magsulph-glycerin dressing Later the carbuncle is excised with a cruciate incision.

3. If the gap is large and when the granulation tissue comes to the surface, skin grafting is done.

Ludwig's Angina

Ludwig's angina is a serious, potentially life-threatening cellulitis or connective tissue infection of the submandibular space. It typically arises from infections of the teeth, particularly the second or third molars, and can lead to airway obstruction due to swelling. This condition is named after the German physician Wilhelm Friedrich von Ludwig, who first described it in the 19th century.

Etiology

• Common Causes:

  • Dental infections (especially from the lower molars)
  • Infections from the floor of the mouth
  • Trauma to the submandibular area
  • Occasionally, infections can arise from other sources, such as the oropharynx or skin.

• Microbial Agents:

  • Mixed flora, including both aerobic and anaerobic bacteria.
  • Common organisms include Streptococcus, Staphylococcus, and Bacteroides species.

Pathophysiology

• The infection typically begins in the submandibular space and can spread rapidly due to the loose connective tissue in this area.
• The swelling can lead to displacement of the tongue and can obstruct the airway, making it a medical emergency.

Clinical Presentation

• Symptoms:

  • Swelling of the submandibular area, which may be bilateral
  • "Brawny induration" (firm, non-fluctuant swelling)
  • Pain and tenderness in the submandibular region
  • Difficulty swallowing (dysphagia) and speaking (dysarthria)
  • Fever and malaise
  • Possible elevation of the floor of the mouth and displacement of the tongue

• Signs:

  • Swelling may extend to the neck and may cause "bull neck" appearance.
  • Trismus (limited mouth opening) may be present.
  • Respiratory distress due to airway compromise.

Diagnosis

• Clinical Evaluation: Diagnosis is primarily clinical based on history and physical examination.
• Imaging:
  • CT scan of the neck may be used to assess the extent of the infection and to rule out other conditions.
  • X-rays may show air in the soft tissues if there is a necrotizing infection.

Management

Initial Management

• Airway Management:
  • Ensure the airway is patent; this may require intubation or tracheostomy in severe cases.

Medical Treatment

• Antibiotics:
  • Broad-spectrum intravenous antibiotics are initiated to cover both aerobic and anaerobic bacteria. Common regimens may include:
    • Ampicillin-sulbactam
    • Clindamycin
    • Metronidazole combined with a penicillin derivative

Surgical Intervention

• Drainage:
  • Surgical drainage may be necessary if there is an abscess formation or significant swelling.
  • Incisions are typically made in the submandibular area to allow for drainage of pus and to relieve pressure.

Complications

• Airway Obstruction: The most critical complication, requiring immediate intervention.
• Sepsis: Can occur if the infection spreads systemically.
• Necrotizing fasciitis: Rare but serious complication that may require extensive surgical intervention.
• Thrombosis of the internal jugular vein: Can occur due to the spread of infection.

Prognosis

• With prompt diagnosis and treatment, the prognosis is generally good. However, delays in management can lead to significant morbidity and mortality due to airway compromise and systemic infection.

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:

1. Acute Upper Airway Obstruction: Conditions such as severe allergic reactions, infections (e.g., epiglottitis), or trauma that obstruct the airway.
2. Major Surgery: Procedures involving the mouth, pharynx, or larynx that may compromise the airway.
3. Prolonged Mechanical Ventilation: Patients requiring artificial ventilation for an extended period, such as those with respiratory failure.
4. 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.

Cardiovascular Effects of Sevoflurane, Halothane, and Isoflurane

• Sevoflurane:

  • Maintains cardiac index and heart rate effectively.

  • Exhibits less hypotensive and negative inotropic effects compared to halothane.

  • Cardiac output is greater than that observed with halothane.

  • Recovery from sevoflurane anesthesia is smooth and comparable to isoflurane, with a shorter time to standing than halothane.

• Halothane:

  • Causes significant decreases in mean arterial pressure, ejection fraction, and cardiac index.

  • Heart rate remains at baseline levels, but overall cardiovascular function is depressed.

  • Recovery from halothane is less favorable compared to sevoflurane and isoflurane.

• Isoflurane:

  • Preserves cardiac index and ejection fraction better than halothane.

  • Increases heart rate while having less suppression of mean arterial pressure compared to halothane.

  • Cardiac output during isoflurane anesthesia is similar to that of sevoflurane, indicating a favorable cardiovascular profile.

TMJ Ankylosis

Temporomandibular Joint (TMJ) ankylosis is a condition characterized by the abnormal fusion of the mandibular condyle to the temporal bone, leading to restricted jaw movement. This condition can significantly impact a patient's ability to open their mouth and perform normal functions such as eating and speaking.

Causes and Mechanisms of TMJ Ankylosis

1. Condylar Injuries:

   • Most cases of TMJ ankylosis result from condylar injuries sustained before the age of 10. The unique anatomy and physiology of the condyle in children contribute to the development of ankylosis.

2. Unique Pattern of Condylar Fractures in Children:

   • In children, the condylar cortical bone is thinner, and the condylar neck is broader. This anatomical configuration, combined with a rich subarticular vascular plexus, predisposes children to specific types of fractures.
   • Intracapsular Fractures: These fractures can lead to comminution (fragmentation) and hemarthrosis (bleeding into the joint) of the condylar head. A specific type of intracapsular fracture known as a "mushroom fracture" occurs, characterized by the comminution of the condylar head.

3. Formation of Fibrous Mass:

   • The presence of a highly osteogenic environment (one that promotes bone formation) following a fracture can lead to the organization of a fibrous mass. This mass can undergo ossification (the process of bone formation) and consolidation, ultimately resulting in ankylosis.

4. Trauma from Forceps Delivery:

   • TMJ ankylosis can also occur due to trauma sustained during forceps delivery, which may cause injury to the condylar region.

Etiology and Risk Factors

Laskin (1978) outlined several factors that may contribute to the etiology of TMJ ankylosis following trauma:

1. Age of Patient:

   • Younger patients have a significantly higher osteogenic potential and a more rapid healing response. The articular capsule in younger individuals is not as well developed, allowing for easier displacement of the condyle out of the fossa, which can damage the articular disk. Additionally, children may exhibit a greater tendency for prolonged self-imposed immobilization of the mandible after trauma.

2. Type of Fracture:

   • The condyle in children has a thinner cortex and a thicker neck, which predisposes them to a higher proportion of intracapsular comminuted fractures. In contrast, adults typically have a thinner condylar neck, which usually fractures at the neck, sparing the head of the condyle within the capsule.

3. Damage to the Articular Disk:

   • Direct contact between a comminuted condyle and the glenoid fossa, either due to a displaced or torn meniscus (articular disk), is a key factor in the development of ankylosis. This contact can lead to inflammation and subsequent bony fusion.

4. Period of Immobilization:

   • Prolonged mechanical immobilization or muscle splinting can promote orthogenesis (the formation of bone) and consolidation in an injured condyle. Total immobility between articular surfaces after a condylar injury can lead to a bony type of fusion, while some movement may result in a fibrous type of union.