What is the Ambler classification - Class C?

From the Guidelines

Ambler Class C, in the context of cardiogenic shock classification, refers to a patient who manifests with hypoperfusion that requires intervention beyond volume resuscitation to restore perfusion, typically presenting with relative hypotension 1. This classification is crucial for determining the appropriate level of care and intervention for patients experiencing cardiogenic shock. The classification system includes:

• A: at risk for cardiogenic shock
• B: beginning cardiogenic shock with clinical evidence of relative hypotension or tachycardia without hypoperfusion
• C: class cardiogenic shock with hypoperfusion requiring intervention
• D: deteriorating/doom with no response to initial interventions
• E: extremis with cardiac arrest and ongoing CPR and/or ECMO support Key characteristics of Class C cardiogenic shock include the need for inotrope, pressor, or mechanical support, such as ECMO, to restore perfusion, and the presence of relative hypotension 1. In clinical practice, identifying the correct classification of cardiogenic shock is essential for guiding treatment decisions and improving patient outcomes. For example, a patient classified as Class C would require immediate intervention to restore perfusion, whereas a patient classified as Class A might be monitored closely for signs of worsening shock. The Ambler classification system provides a framework for clinicians to assess the severity of cardiogenic shock and provide appropriate care. It is essential to note that the classification system is based on physical examination, biochemical markers, and hemodynamics, and accurate assessment is critical for effective management 1.

From the Research

Ambler Classification - Class C

The Ambler classification is used to categorize the severity of peripheral arterial disease (PAD) based on the ankle-brachial index (ABI) and toe-brachial index (TBI) values.

• Class C in the Ambler classification is not explicitly defined in the provided studies, however, we can look at the general understanding of ABI and TBI values to understand the different classes.
• The studies 2, 3, 4, 5, 6 provide information on the ABI and TBI values in different populations, including those with PAD, diabetes, and chronic kidney disease.

ABI and TBI Values

• The ABI values are generally categorized as follows:
  • Normal: 0.9-1.4
  • Borderline: 0.8-0.9
  • Abnormal: <0.9
  • Non-compressible: >1.4
• The TBI values are generally categorized as follows:
  • Normal: 0.7-1.2
  • Borderline: 0.6-0.7
  • Abnormal: <0.6
  • Non-compressible: >1.2
• However, the provided studies do not explicitly mention the Ambler classification or Class C, but they do discuss the importance of ABI and TBI in diagnosing PAD and their limitations in certain populations, such as those with diabetes or chronic kidney disease.

Limitations of ABI and TBI

• The studies 2, 4 highlight the limitations of ABI in diagnosing PAD in patients with diabetes, as medial arterial calcification can lead to falsely elevated ABI values.
• The study 3 discusses the use of Doppler ultrasonography-derived maximal systolic acceleration (ACCmax) as a potential alternative to ABI and TBI in diagnosing PAD.
• The study 5 evaluates the accuracy of ABI, TBI, and risk classification score in discriminating PAD in patients with chronic kidney disease, and finds that combining risk score with ABI, alternative ABI, and TBI increases the accuracy of PAD classification.
• The study 6 provides reference values for ABI, TBI, and pulse volume recording in healthy young adults, and highlights the importance of considering age and sex when evaluating circulatory indexes.