Oxygen, Resuscitation & Clinical Outcomes in Critical Care

John Myburgh speaks passionately about the use of oxygen in resuscitation, and clinical outcomes in critical care. For the 30 years, clinical understanding of haemodynamic resuscitation has been based on physiological paradigms that focus on convective oxygen delivery. Most of these emphasise the role of cardiac output, haemoglobin and recommend interventions using synthetic agents such as dobutamine, synthetic colloids and blood transfusions. However, markedly influenced by industry, these interventions and strategies hijacked critical thinking creating a belief in the utility of attaining short-term physiological surrogates for resuscitation that have little relevance in improving patient-centred outcomes. This ‘physiological fallacy’ has been demonstrated in high-quality RCTs of fluids, goal-directed therapy and catecholamines, that paradoxically inform the interpretation of new insights in the physiological basis of health and disease. In this talk John presents two halves. In the first half, he discusses oxygen delivery. He begins with the oxygen cascade and applies this to the current thinking by some on oxygen delivery in critical care. He believes the two are incongruous. Measuring and altering oxygen is achieved using expensive toys and is likely not having a great impact on patient outcomes. John questions the whole concept of driving P02 to influence patient outcomes and mortality. In the second half John talks about the ‘physiological fallacy’ – the clinical practice of relying on variables we cannot accurately measure and do not understand. He presents a different approach. Physiology and haemodynamics encompass complex processes under intense neurohormonal vasoregulation. There is no one simple metric to rely on, such as V02 or D02. When considering a patient, the clinician must use their brain. John stresses the importance of focusing on understanding the disease process in its entirety rather than chasing instant gratification by altering a number. Work out where your patient exists on a spectrum. Consider acute versus chronic presentation, as well as compensated versus decompensated patients. This will dictate treatment. The situation usually complex and dynamic… Treat it as such.

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