Tuesday, September 10, 2024

EMS Equipment - Murphy's Endotracheal Tube


For EMS providers, understanding the Murphy Endotracheal Tube and its key feature, the “Murphy Eye,” is essential for ensuring patient safety during airway management. 

The Murphy eye serves as a critical safety mechanism that prevents complete airway obstruction if the main distal opening of the tube becomes blocked. It is also an example of an eponymous medical term.

Recognizing this feature and the overall design of the endotracheal tube can help prevent complications during intubation and ensure the continued delivery of oxygen to patients in emergency situations.

The “Murphy Eye” Explained

The Murphy Eye is the eponymous term for a small hole on the side of most endotracheal tubes (ETTs). It functions as a vent, preventing complete obstruction of the patient’s airway if the primary distal opening of the ETT becomes occluded.

Dr. Francis J. Murphy (1900–1972) was a strong advocate for the continuous supply of oxygen during anesthesia. In 1941, he outlined the nine characteristics of the "ideal" endotracheal tube (ETT). In the same article, he introduced two tubes with innovative features. 

One tube was straight with two side holes, while the other was curved with one side hole. Both lacked cuffs and were made from high-quality red rubber that balanced flexibility with resistance to compression or kinking, even after multiple uses and heat sterilizations.

Although most ETTs today are made from disposable plastic, they still require a similar balance of flexibility and resistance to compression. Most continue to incorporate the crucial safety feature that bears Dr. Murphy's name: the "Murphy eye."

The featured image show the orginal tube, owned by Dr. Murphy himself, and bears his initials. It features an inflatable cuff located above the "eye," which is inflated via a small side tube attached to the ETT. 

Further Reading:

Bledsoe, B. E., Cherry, R. A. & Porter, R. S (2023) Paramedic Care: Principles and Practice (6th Ed) Boston, Massachusetts: Pearson

Brown, C. A. (2022) Walls Manual of Emergency Airway Management (5th Ed). Philadelphia, Pennsylvania: Lippincott, Williams & Wilkins.

Sunday, September 08, 2024

EMS Medical Terminology - Sellick's Maneuver


EMS providers should be familiar with the Sellick Maneuver, also known as cricoid pressure, as a technique designed to reduce the risk of regurgitation and aspiration during endotracheal intubation, particularly in patients who are not fasting or at high risk of vomiting. It is an example of an eponymous medical term.

It was first described by Dr. Brian Sellick in 1961 and has been used in emergency and anesthetic situations ever since. 

However, it’s essential for EMS providers to apply the right amount of pressure and know that this technique is sometimes debated due to concerns that it may obstruct the airway or complicate intubation in some cases.

Here's what they should know:

Key Concepts

Anatomy Involved:

The cricoid cartilage is a ring-shaped structure located just below the thyroid cartilage in the neck.

When performing the Sellick Maneuver, downward pressure is applied to the cricoid cartilage, which in turn compresses the esophagus against the vertebral column, theoretically reducing the chance of regurgitation by preventing stomach contents from moving into the pharynx.

When to Use It:

Primarily used during rapid sequence intubation (RSI) to protect the airway in emergency situations, especially when there's a high risk of vomiting (e.g., trauma patients, those who have recently eaten, or have decreased consciousness).

It may also be employed during bag-valve-mask (BVM) ventilation to prevent gastric insufflation, although this use is somewhat controversial.

How to Perform It:

The provider places firm, continuous pressure using the thumb and forefinger on the cricoid cartilage (located below the Adam’s apple).

The recommended pressure is about 10 Newtons (≈1 kg of force) initially, increasing to 30-40 Newtons (≈3-4 kg of force) once the patient loses consciousness, as the risk of vomiting increases at that point.

Controversies & Limitations:

Questionable Efficacy: Studies over the years have raised doubts about the effectiveness of the Sellick Maneuver in completely preventing regurgitation or aspiration. In some cases, it may even impair ventilation or visualization of the airway during intubation, particularly in difficult airway scenarios.

Potential Complications: Incorrect application of the maneuver (too much force or misplacement of pressure) can result in airway obstruction or displacement of the esophagus laterally rather than compressing it.

Many modern airway protocols have deemphasized its routine use and instead focus on optimal intubation techniques and preparation for managing airway complications.

Training & Clinical Judgment:

EMS providers should be well-trained in applying the maneuver correctly, but also be aware that if it interferes with ventilation or intubation, it should be discontinued.

It’s essential to assess the specific patient scenario (e.g., suspected difficult airway) and weigh the benefits and risks of applying cricoid pressure.

Summary

The Sellick Maneuver was historically considered a key technique for preventing aspiration during emergency intubation, but its effectiveness is now debated. 

EMS providers should understand the anatomy, application method, and potential complications, and apply it judiciously based on the clinical situation.

Further Reading:

Alexander, M. & Belle, R. (2017) Advanced EMT: A Clinical Reasoning Approach (2nd Ed). Hoboken, New Jersey: Pearson Education

Bledsoe, B. E., Cherry, R. A. & Porter, R. S (2023) Paramedic Care: Principles and Practice (6th Ed) Boston, Massachusetts: Pearson

Brown, C. A. (2022) Walls Manual of Emergency Airway Management (5th Ed). Philadelphia, Pennsylvania: Lippincott, Williams & Wilkins.

Ebright, C. (2024) Unique Patient Signs: A Case Study. EMS1. Accessed May 1, 2024

Mistovich, J. J. & Karren, K. J. (2014) Prehospital Emergency Care (11th Ed). Hoboken, New Jersey: Pearson Education

Peate, I. & Sawyer, S (2024) Fundamentals of Applied Pathophysiology for Paramedics. Hoboken, New Jersey:  Wiley Blackwell

Friday, September 06, 2024

EMS Airway Emergencies - Esophageal Varices


Esophageal Varices
are abnormally dilated veins in the lower part of the esophagus that develop as a result of portal hypertension, commonly due to liver cirrhosis. 

These varices pose a high risk of massive upper gastrointestinal (GI) bleeding, which can be life-threatening. 

When esophageal varices rupture, they can cause severe hematemesis (vomiting of blood), shock, and potentially death if not managed promptly.

Causes and Pathophysiology

- Portal Hypertension: The most common cause of esophageal varices is liver cirrhosis (often due to chronic alcohol use, hepatitis B or C, or fatty liver disease).

Portal hypertension occurs when the liver becomes scarred and obstructs blood flow, leading to increased pressure in the portal venous system.

- Collateral Circulation Formation: To relieve this increased pressure, the body forms collateral blood vessels (varices) in the esophagus and stomach. These varices are thin-walled and prone to rupture.

- Rupture and Hemorrhage: When pressure becomes too high or if the varices are mechanically disrupted (e.g., vomiting, coughing), they can rupture, leading to severe bleeding.

Signs and Symptoms of Esophageal Variceal Bleeding

EMS providers should be alert for the following symptoms in patients with a known history of liver disease or portal hypertension:

- Profuse Hematemesis: Patients often present with large volumes of bright red blood in vomit, which is the hallmark sign of a ruptured varix.

- Melena or Hematochezia: Blood may pass through the GI tract and present as black, tarry stools (melena) or bright red rectal bleeding (hematochezia), depending on the speed and severity of the bleed.

- Hypovolemic Shock: Tachycardia and hypotension are common signs. Cool, clammy skin, altered mental status, and pallor indicate worsening shock.

- Signs of Liver Disease: 

  • Jaundice (e.g., yellowing of the skin and eyes)
  • Ascites (e.g., swollen abdomen due to fluid accumulation)
  • Spider Angiomata (e.g., visible, web-like blood vessels on the skin)
  • Hepatic Encephalopathy (e.g., confusion, altered consciousness)

Prehospital Assessment

- Scene Size-Up and Initial Impression: Evaluate the scene for large amounts of blood, which can indicate massive hemorrhage.

Assess for a patient history of liver disease, alcoholism, or known cirrhosis.

- Airway & Breathing: Monitor for airway obstruction due to blood in the mouth or pharynx.

Be prepared to suction the airway frequently to prevent aspiration.

Assess respiratory status and provide high-flow oxygen if needed.

- Circulatory Assessment: Check for signs of shock (e.g., tachycardia, hypotension).

Establish large-bore IV access (18 gauge or larger) for potential fluid and medication administration.

Monitor mental status and skin condition (pallor, coolness).

- Focused History & Physical Exam: Ask about the patient’s history of liver disease, alcohol use, hepatitis, or prior variceal bleeding.

Inquire about recent triggers (e.g., vomiting, straining, recent alcohol binge) that may have precipitated bleeding.

Prehospital Treatment and Management

Managing esophageal varices in the prehospital setting is challenging and requires prompt, aggressive intervention to control bleeding and prevent shock.

1. Airway Management

- Suctioning: Keep a suction device readily available for continuous use to clear the airway of blood.

- Airway Positioning: Consider placing the patient in the left lateral recumbent position if unconscious to reduce the risk of aspiration.

- Definitive Airway: If the patient is at risk of losing their airway (e.g., massive hematemesis or altered mental status), consider early endotracheal intubation, if within your scope and if protocols allow.

2. Hemodynamic Support

- IV Fluid Resuscitation: Establish two large-bore IVs and begin fluid resuscitation with isotonic crystalloids (e.g., normal saline) if the patient shows signs of hypovolemic shock.

Avoid aggressive fluid overload, as it can increase portal hypertension and worsen bleeding.

- Blood Products: If available (e.g., in critical care transport), consider initiating blood transfusion early in patients with significant bleeding or hemorrhagic shock.

3. Medications

- Vasoactive Agents (for ALS Providers): If within your scope and protocol, consider octreotide or vasopressin, which can reduce portal pressure and control variceal bleeding (requires medical control consultation).

- Anti-Emetics: Administer antiemetics (e.g., ondansetron) to prevent retching and reduce the risk of worsening the variceal tear.

4. Rapid Transport and Early Notification

- Transport Priority: All patients with suspected variceal bleeding should be considered critical and require rapid transport to the nearest facility with endoscopic capabilities and surgical backup.

- Early Notification: Notify the receiving hospital as early as possible about the suspected diagnosis, so the facility can mobilize appropriate resources.

Differentiating from Other GI Bleeds

- Peptic Ulcer Disease: Often presents with coffee-ground emesis and less profuse bleeding.

- Mallory-Weiss Syndrome: Similar to varices but generally involves small, non-life-threatening mucosal tears with moderate bleeding.

- Gastric Cancer or Erosive Gastritis: May have chronic, low-volume bleeding rather than acute hemorrhage.

Who Discovered Esophageal Varices?

Esophageal Varices themselves are not attributed to a specific individual. They were gradually recognized as a consequence of portal hypertension in patients with liver disease, a concept that evolved over centuries of clinical observation. 

The condition was first described in detail in the early 20th century, as the understanding of cirrhosis and portal hypertension advanced. 

The development of endoscopy in the mid-20th century allowed for more precise diagnosis and management of this life-threatening condition.

Key Considerations for EMS Providers

- Early Recognition: Suspect esophageal varices in any patient with massive hematemesis and a history of liver disease or alcohol abuse.

- Airway Safety: Suctioning and airway management are critical to prevent aspiration.

- Shock Management: Focus on maintaining perfusion with controlled fluid resuscitation.

- Definitive Treatment is Hospital-Based: EMS management is primarily supportive, with rapid transport to a facility that can perform endoscopy and possible surgical interventions.

Further Reading:

Alexander, M. & Belle, R. (2017) Advanced EMT: A Clinical Reasoning Approach (2nd Ed). Hoboken, New Jersey: Pearson Education

Brown, C. A. (2022) Walls Manual of Emergency Airway Management (5th Ed). Philadelphia, Pennsylvania: Lippincott, Williams & Wilkins

Bledsoe, B. E., Cherry, R. A. & Porter, R. S (2023) Paramedic Care: Principles and Practice (6th Ed) Boston, Massachusetts: Pearson

Meseeha, M., & Attia, M. (2023) Esophageal Varices. StatPearls. Treasure Island, Florida: StatPearls. Accessed September 28, 2024

Mistovich, J. J. & Karren, K. J. (2014) Prehospital Emergency Care (11th Ed). Hoboken, New Jersey: Pearson Education

Peate, I. & Sawyer, S (2024) Fundamentals of Applied Pathophysiology for Paramedics. Hoboken, New Jersey:  Wiley Blackwell