EMS Anatomy & Physiology - Mammalian Diving Response Syndrome

EMS Providers should be familiar with the Mammalian Diving Response Syndrome as it is a physiological reflex that can have critical implications during emergency scenarios, especially those involving drowning, cold-water immersion, or apnea. 

Here are some key points to know:

Definition:

The Mammalian Diving Response Syncdrome is a reflex primarily triggered by submersion in cold water or holding one’s breath. 

It is characterized by specific physiological changes that help conserve oxygen and protect vital organs during hypoxia. 

This response is more pronounced in children and is part of an evolutionary adaptation found in many mammals.

Physiological Mechanisms:

The diving response involves three primary components:

- Bradycardia: The heart rate slows down significantly to reduce oxygen consumption by non-essential tissues.

- Peripheral Vasoconstriction: Blood vessels in the extremities constrict, redirecting blood flow to vital organs like the brain and heart.

- Blood Shift (during deep dives): In humans, blood is directed away from the lungs and limbs to maintain pressure and prevent lung collapse during deep dives.

Triggers:

Submersion of the face in water, especially cold water.

Holding breath (apnea).

Psychological stress, such as fear or panic.

Clinical Implications for EMS: 

Understanding the diving response is crucial because it affects how a patient may present and how to manage their condition:

- Bradycardia Management: EMS providers might encounter significantly reduced heart rates in drowning or near-drowning victims.

Bradycardia could be misinterpreted as a sign of severe hypoxia, but it’s a protective mechanism rather than a sign of complete cardiac failure.

Avoid aggressive measures to increase heart rate unless the patient shows other signs of instability.

- Respiratory Considerations: The diving response may cause prolonged breath-holding, so patients might appear apneic or have delayed hypoxic symptoms.

Observe for hypoxia carefully and administer oxygen as indicated.

- Pediatric Considerations: The diving response is more prominent in children, which is why some drowning victims can survive prolonged submersion with relatively less neurological damage.

Cold water can extend the safe resuscitation window in pediatric patients.

- Cardiac Arrest in Cold Water: During cold water submersion, the body’s metabolic rate decreases significantly, which can potentially improve resuscitation outcomes even after prolonged submersion.

Follow hypothermia protocols and prolonged resuscitation efforts in cases of drowning in cold water.

Treatment and Management:

- ABC Approach: Focus on Airway, Breathing, and Circulation.

Hypothermia Management: Consider hypothermia treatment protocols as the mammalian diving response is often accompanied by cold water immersion.

Consider ECLS/ECMO in severe cases: In cases of cardiac arrest with diving reflex activation, specialized centers might use Extracorporeal Life Support (ECLS) or Extracorporeal Membrane Oxygenation (ECMO).

Key Takeaways:

Do not confuse bradycardia with imminent cardiac arrest. It can be a protective adaptation.

Cold-water submersion can improve survival outcomes—keep in mind for prolonged resuscitation in cold environments.

Children are more likely to benefit from the diving response due to their physiology.

Understanding this reflex allows EMS providers to better assess, treat, and manage patients exposed to cold water or other scenarios that can induce the diving response.

Who Discovered The Mammalian Diving Response Syndrome?

The mammalian diving response was first described by Edmund Goodwyn in 1786. However, it was extensively studied and popularized by Paul Bert and later Johan E. Severin Nilsson in the late 19th and early 20th centuries.

Goodwyn, a British physician, observed physiological changes in animals and humans during submersion. His initial work laid the foundation for understanding the reflex, but it was Paul Bert who made significant contributions by studying the effects of breath-holding and diving on the heart rate and blood flow.

Johan E. Severin Nilsson, a Swedish physiologist, further refined the concept, investigating how immersion and apnea affected circulation and oxygen usage in various mammals. His research solidified the understanding of the mammalian diving reflex as a protective adaptation seen across multiple species, including humans.

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

Godek, D., & Freeman, A. M. (2022) Physiology, Diving Reflex. Treasure Island, Florida: StatPearls Publishing

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

Panneton, W. M. (2013) The Mammalian Diving Response: An Enigmatic Reflex To Preserve Life? Physiology 28(5): 284-97. Accessed October 6, 2024

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

EMS Anatomy & Physiology - Curvature of the Spine

 

EMS Providers should have a basic understanding of skeletal issues like kyphosis, lordosis, and scoliosis, as well as related problems, to provide appropriate care for patients.

Here are a few key points:

Identification: EMS providers should be able to identify these skeletal issues through visual observation and patient history.

1. Kyphosis: Kyphosis refers to an excessive forward curvature of the upper spine, leading to a rounded or hunched posture. It can be caused by several factors, including poor posture, osteoporosis, spinal fractures, or certain medical conditions. EMS providers should be aware of the potential for compromised breathing and mobility in patients with severe kyphosis.

2. Lordosis: Lordosis is an excessive inward curvature of the lower spine, commonly known as swayback. It can be caused by various factors such as obesity, pregnancy, muscle imbalances, or certain medical conditions. EMS providers should be cautious of potential back pain and difficulty maintaining a supine position in patients with pronounced lordosis.

3. Scoliosis: Scoliosis is a medical condition characterized by an abnormal sideways curvature of the spine. This condition can manifest in various degrees of severity and is often idiopathic, meaning the cause is unknown. However, it can also result from congenital factors, neuromuscular conditions, or trauma.

Symptoms: Be aware of common symptoms associated with these conditions, such as pain, limited range of motion, and respiratory difficulties, which can occur due to the abnormal spinal curvature.

Assessment: Conduct a thorough physical assessment to evaluate the severity of the condition, including the degree of curvature, associated deformities, and neurological symptoms.

Stabilization: When immobilizing the patient, EMS providers should consider the unique spinal curvature and use appropriate spinal immobilization techniques to ensure patient comfort and safety. This may involve padding and positioning devices to accommodate the curvature.

Transport: Ensure safe and appropriate transport of patients with these conditions. They may require specialized equipment, such as scoop stretchers or vacuum mattresses, to maintain proper spinal alignment.

Communication: Effective communication with the patient is crucial. Ensure the patient is comfortable and aware of the care being provided. Also, obtain a medical history to determine if there are underlying causes or exacerbating factors related to the skeletal issue.

Related Problems: Understand that these skeletal issues can lead to other medical problems. For example, kyphosis and lordosis can cause respiratory issues by reducing lung capacity, so monitor the patient's respiratory status carefully. They might also be at a higher risk of spinal fractures or other spinal cord injuries. Additionally, scoliosis can sometimes be associated with cardiac and pulmonary complications, which should be considered during patient assessment.

Medication and Pain Management: Be aware of any medications the patient is taking, as well as their potential side effects and interactions. Patients with these conditions may require pain management during transport, so be prepared to administer appropriate pain relief under medical direction.

Special Considerations: Individuals with skeletal issues may require special handling, including assistance with transfers, lifting, or moving the patient. Consider the patient's comfort and any potential complications that may arise from moving them.

Collaboration: Work closely with other healthcare providers, including receiving facilities and specialists, to ensure a seamless transition of care and to address any specific needs related to the patient's condition.

Conclusion

Remember that each patient's needs may vary, so adapt your care accordingly. Additionally, staying updated on current guidelines and protocols for spinal immobilization and care of patients with skeletal issues is essential to providing appropriate care in the field.

It is always important to work collaboratively with other healthcare professionals to ensure optimal care for patients with these conditions.

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 Volume 1 (6th Ed) Pearson.  

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