Trauma

Question 1

What is the equation to calculate blood volume in adult male, adult female, child, infant?

Answer 1

The equations to calculate blood volume are based on weight, with slight variations for adults and children. For adult males, blood volume is approximately 66 mL/kg. For adult females, it’s around 60 mL/kg. In children, blood volume is approximately 70-80 mL/kg or 8-9% of body weight and in infants the blood volume is considered to be about 8-9% of body weight as well.

Summary

• Adult male blood volume: 66 mL/kg
• Adult female blood volume: 60 mL/kg
• Child blood volume: 70-80 mL/kg or 8-9% of body weight
• Infant blood volume: 70-80 mL/kg or 8-9% of body weight

Context / Supporting Information / Comprehensive Review

Blood volume is a critical parameter in assessing a patient’s hemodynamic status, especially in cases of hemorrhage or fluid imbalance. It’s essential to understand how to estimate this volume across different age groups for appropriate medical management. The sources provide specific formulas and guidelines for calculating blood volume in adults, children, and infants.

• Adults:
  
  • The estimated blood volume in adults is based on lean body weight.
  • For adult males, the blood volume is calculated as approximately 66 mL/kg of lean body weight. For example, a 75 kg male would have a blood volume of approximately 5 liters (66 mL/kg * 75 kg).
  • For adult females, the blood volume is approximately 60 mL/kg of lean body weight. For example, a 60 kg female has an estimated blood volume of 3.6 liters (60 mL/kg * 60 kg).
  • These calculations are essential for determining fluid resuscitation needs in cases of blood loss.
• Children:
  
  • Blood volume in children is higher relative to their weight compared to adults.
  • The estimated blood volume in children is approximately 70-80 mL/kg, or 8-9% of their body weight. This can be used to estimate blood volume and fluid resuscitation needs in children.
  • For example, a 10 kg child would have approximately 700-800 mL of blood volume, (70 mL/kg * 10 kg to 80 mL/kg * 10 kg).
  • The blood volume for a child is calculated as 8% to 9% of body weight, or 70-80 mL/kg.
• Infants
  
  • Like children, an infant’s blood volume is around 8-9% of their body weight or about 70-80 mL/kg.
  • For example, a 3.5 kg infant has an approximate blood volume of 245 to 280 mL (70 mL/kg * 3.5 kg to 80 mL/kg * 3.5 kg)
  • It is important to note that in the setting of pediatric trauma, fluid and medication dosages are weight-based.

It’s important to note that these are estimations, and individual variations exist. However, these formulas serve as practical guidelines for clinical assessment and management. When calculating blood volume, remember to use the patient’s lean body weight rather than total weight, especially in obese individuals, to avoid overestimation. These estimations are important for determining fluid resuscitation and medication dosages.

Question 2

How do you treat hyphema? (medications, other)

Answer 2

Concise Answer
The medical management of hyphema aims to prevent rebleeding, reduce intraocular pressure, and promote the clearance of blood from the anterior chamber. It includes measures such as hospitalization with bed rest, head elevation, topical medications like cycloplegics and corticosteroids, and potentially systemic antifibrinolytics, carbonic anhydrase inhibitors, or osmotic agents.

Summary
Medical treatment for hyphema focuses on preventing further bleeding and managing the symptoms. This typically involves hospitalization with bed rest, elevating the head, and administering topical medications to control inflammation, pain, and intraocular pressure.

Context / Supporting information / Comprehensive review
Medical management of hyphema is crucial for preventing complications and promoting healing. It is focused on several key areas:

• Hospitalization and Rest: Patients with hyphema may require hospitalization with bed rest.
  
  • Elevation of the head of the bed is important to promote the settling of blood and to prevent venous congestion.
• Topical Medications: Several types of topical medications may be used in the management of hyphema:
  
  • Cycloplegics, such as atropine, are administered to immobilize the iris and prevent further bleeding.
  • Corticosteroids are recommended to reduce intraocular inflammation.
• Management of Intraocular Pressure:
  
  • Beta blockers, such as timolol, can be used to control high intraocular pressure.
  • Carbonic anhydrase inhibitors may also be used to reduce intraocular pressure.
  • Systemic hyperosmotics, such as mannitol, may be needed to lower intraocular pressure when topical medications are not enough.
• Antifibrinolytics:
  
  • Aminocaproic acid (Amicar) may be recommended to reduce the risk of rebleeding.
• Other Medications: While not specifically for hyphema, it is important to note that medications that affect coagulation should be avoided.
  
  • Aspirin is absolutely contraindicated due to the increased risk of rebleeding.
• Monitoring: Daily monitoring of intraocular pressures is crucial. Patients should also be monitored for rebleeding, which usually occurs 3-5 days after the initial injury.
• Considerations: It is important to note that some patients with specific conditions may require modifications to this treatment approach. For example, patients with a history of bleeding disorders, those who are on anticoagulants, or those with certain cardiac conditions, should have their treatment carefully tailored to their needs.
• When Medical Management is Insufficient: When medical management is unable to control intraocular pressure, clear the blood, or prevent rebleeding, surgical intervention may be needed.

Question 3

How is hyphema graded?

Answer 3

Grades 1-IV and microhyphema

Question 4

Identify the topical hemostatic agents that can be used intraoperatively to control hemorrhage?

Answer 4

Surgiflo
Surgiflo is not explicitly mentioned in the provided sources.

Gelfoam
* Composition: Gelfoam is an absorbable gelatin sponge made from dried and sterilized porcine skin gelatin.
* Mechanism of Action: It serves as a matrix or scaffold that facilitates clot formation. Gelfoam is a porous and pliable sponge that conforms to irregular wound geometries and can absorb many times its weight in water. When applied, Gelfoam swells and provides a tamponade effect in confined spaces, restricting blood flow and providing a matrix for clot formation. It promotes platelet disruption and the formation of a fibrin framework, leading to blood clot formation.
* Advantages: Gelfoam is relatively inexpensive and has a neutral pH. It is also completely resorbable, liquefying in approximately 7 days and being fully resorbed within 4 to 6 weeks.
* Disadvantages: Gelfoam’s swelling after application may cause tissue or neural damage due to compression. There is also a risk of dislodgement from the bleeding site. Gelfoam may cause excessive granuloma or fibrosis.
* Use: Gelfoam is particularly useful for capillary-type bleeding. It can be used alone or moistened with thrombin.

Avitene
* Composition: Avitene is microfibrillar collagen hemostat made from purified bovine collagen that is processed into microcrystals.
* Mechanism of Action: Avitene works by contact activation and promotion of platelet aggregation, which occurs as a result of contact between blood and collagen. It provides an actual collagen matrix that facilitates clot formation.
* Advantages: It is particularly effective for large surface areas and provides superior hemostasis compared to gelatin and cellulose.
* Disadvantages: Avitene can be difficult to handle and is relatively expensive. Between 2% to 4% of the total population are allergic to bovine collagen.
* Use: Avitene is used for surface bleeding and areas where hemostasis is difficult to achieve with conventional methods.

Surgicel
* Composition: Surgicel is made of oxidized regenerated cellulose.
* Mechanism of Action: It provides a platform for platelet aggregation and activation due to its low pH. Surgicel absorbs blood into a scaffold of knitted cellulose, providing a matrix for thrombus formation. It expands three to four times its original size and converts to a gel.
* Advantages: Surgicel is easy to handle and offers antimicrobial coverage due to its low pH. It is also bactericidal, making it a preferred hemostatic agent.
* Disadvantages: Its low pH may lead to postoperative irritation, and it may cause a foreign body reaction. It needs to be removed after hemostasis is achieved. Oxidized cellulose can cause nerve paresthesia when applied directly on or in immediate vicinity to nerves.
* Use: Surgicel is applied by placing it directly on the bleeding site.

Collaplug
* Composition: Collaplug is a collagen-based hemostatic agent.
* Mechanism of Action: It stimulates platelet adherence and promotion of platelet aggregation. It can absorb many times its own weight in fluids.
* Advantages: Collaplug is relatively inexpensive and resorbs in 10–14 days.
* Disadvantages: Collagen-based products have the potential to cause allergic reactions in individuals sensitive to bovine-derived materials.
* Use: It is often used in extraction sockets to control bleeding and promote clot formation.

These topical hemostatic agents play a crucial role in managing bleeding during surgical procedures. Each agent has unique properties that make it suitable for specific situations, and understanding these differences can help clinicians choose the most appropriate agent for optimal hemostasis.

Question 5

Retromandibular vein review?

Answer 5

Here is a comprehensive review of the retromandibular vein, including its anatomy, relationships with surrounding structures, and surgical considerations, based on the provided sources:

Concise Answer
The retromandibular vein, formed by the joining of the superficial temporal and maxillary veins, is located within the parotid gland and descends posterior to the mandibular ramus. It plays a crucial role in venous drainage from the face and has significant surgical implications due to its proximity to the facial nerve and other vital structures.

Summary
The retromandibular vein is a key anatomical structure in the face, essential for understanding venous drainage and surgical approaches in the parotid and mandibular regions. Its formation, course, and relationship to surrounding structures like the facial nerve, parotid gland, and external carotid artery make it a critical consideration in surgical procedures. Awareness of the retromandibular vein helps surgeons minimize complications and ensure effective venous drainage.

Context / Supporting Information / Comprehensive Review

Anatomy of the Retromandibular Vein
* Formation: The retromandibular vein is created by the confluence of the superficial temporal and maxillary veins. This occurs within the parotid gland, medial to the mandibular condylar neck.
* Course: The vein descends through the parotid gland, positioned superficial to the external carotid artery and deep to the facial nerve. It runs just posterior to the ramus of the mandible.
* Divisions: As the retromandibular vein descends, it divides into an anterior and a posterior portion.
* The anterior portion joins the facial vein and then empties into the internal jugular vein.
* The posterior portion unites with the posterior auricular vein and then empties into the external jugular vein.

Relationships with Surrounding Structures
* Facial Nerve: The retromandibular vein is closely related to the facial nerve. It lies deep to the facial nerve within the parotid gland.
* Parotid Gland: The vein is located within the substance of the parotid gland. Its position requires careful dissection during parotid surgery.
* External Carotid Artery: The retromandibular vein runs superficial to the external carotid artery as it descends through the parotid gland.
* Mandible: The vein is situated just posterior to the ramus of the mandible. This proximity is important in surgical approaches to the mandible.
* Superficial Temporal Vein: The superficial temporal vein enters the superior surface of the parotid gland and receives the internal maxillary vein to become the retromandibular vein. This lies immediately deep to the marginal mandibular branch of the facial nerve.

Venous Drainage
* The retromandibular vein serves as a primary venous outlet for the face.
* It drains the area corresponding to the distribution of the facial, maxillary, and superficial temporal arteries.
* The vein’s anterior branch connects with the facial vein, which then empties into the internal jugular vein.
* The posterior branch joins the posterior auricular vein to form the external jugular vein.

Surgical Considerations
* Retromandibular Approach: The retromandibular approach is used to expose the ramus and condylar neck/head of the mandible. The incision typically begins below the earlobe and extends inferiorly. Dissection is carried out bluntly through the parotid gland in an anteromedial direction.
* Risk of Injury: During surgical procedures, the retromandibular vein is at risk of injury. Excessive dissection or accidental damage to the vessel can lead to complications.
* Marginal Mandibular Nerve: The marginal mandibular branch of the facial nerve is at risk during retromandibular approaches. Dissection should be meticulous to avoid injury to this nerve.
* Ligation: The retromandibular vein rarely requires ligation unless it is inadvertently transected during surgery.
* Recipient Vein: The retromandibular vein can serve as a recipient vein for free flap reconstruction.

Clinical Significance
* Infection: Deep anastomoses with the pterygoid plexus of veins may lead to retrograde infection.
* Trauma: The common facial vein, which receives drainage from the retromandibular vein, is often violated in cases of traumatic hemorrhage.
* Cavernous Sinus Thrombosis: Infection from the maxilla may follow the maxillary vein to the pterygoid plexus veins and then to the cavernous sinuses via emissary veins, potentially causing infected cavernous sinus thrombosis.
* Plunging Ranula: Unusual clinical variants like the plunging ranula can extend near the submandibular gland region, which is relevant to the path of the retromandibular vein.

Surgical Techniques and Approaches
* Modified Retromandibular Approach: This approach encourages dissection between the marginal mandibular and buccal branches of the facial nerve, continuing through the masseter muscle to bone.
* Skin Incision: The skin incision for the retromandibular approach is typically a vertical line placed just posterior to the posterior border of the ascending ramus, originating slightly inferior to the ear lobe.

By understanding the detailed anatomy, relationships, and surgical implications of the retromandibular vein, surgeons can better navigate complex procedures, minimize complications, and optimize patient outcomes.