Sir, I write further to the excellent poster: Medical emergencies in the dental practice.1

With medical emergencies the risk of mortality multiplies with co-morbidities, especially so in managing sepsis, when organ dysfunction follows the deregulated response to infection.2 Undoubtedly in patients with both sepsis and COPD (chronic obstructive pulmonary disease) time management is critical.

Such patients demonstrate greater risks of acute exacerbation, pneumonia and mortality compared to those with one condition.3 While a single Red Flag Sign triggers blue light transfer, one sign: Needs oxygen to keep Sp O2 92% (88% in COPD) is noteworthy when managing the patient at risk of sepsis, but who has COPD. Discussion with the authors revealed the following:

  1. 1.

    The Sepsis Trust Screening Tool follows NICE Guideline NG51 (1.4.2): high sepsis risk follows the need to maintain oxygen saturations more than 92% or more than 88% where COPD is known.4 This guideline is followed for medical but not dental practices, where SpO2 is to be kept at specific saturation levels1

  2. 2.

    With sepsis and COPD, pragmatic rather than dogmatic approaches are vital, the oxygen dissociation curve shifts left, partial oxygen pressure decreases and haemoglobin's oxygen binding increases. With erythrocyte membrane deformation and disordered microvasculature leading to multi organ failure in sepsis, the consequences following inaccurate arteriolar oximetry are seldom less than catastrophic2

  3. 3.

    Maintaining SpO2 as a sign of sepsis is novel, but requires a pulse oximeter, which not every dental practice has. NICE helpfully recommend maintaining 40% FiO2 (inspired oxygen fraction) as a sepsis-sign.4 FiO2 is calculated by adding the volume of 100% O2 given, to the volume of air inspired: 21% O2 (each breath being: 0.7 X body weight in Kg) and dividing these by total volume of O2 and air

  4. 4.

    Being cool, calm, collected then calculating in an emergency is a rare skill. Thankfully, patients with COPD at risk of hypercapnic failure carry alert cards and colour-coded Venturi high flow oxygen filters, commonly: Blue (24%) and White (28%).5 Should a dental patient at risk of sepsis with COPD become hypoxic, ascending from Blue, to White then the Red (40%) Venturi visibly declares an emergency and an ambulance is called

  5. 5.

    With the Red Venturi, the patient's respiratory demand is safely exceeded with a titrated high-flow ventilation volume of 12 L/min O2 (50 L/min O2:air volume), matching higher ventilatory demands, reducing immediate risks from tissue hypoxaemia, delaying risks from atelectasis, pulmonary vasoconstriction and pulmonary perfusion:ventilation mismatch causing respiratory acidosis.5

Certainly, giving oxygen in a dental practice is neither free, nor free from risk, especially in patients who may have both conditions. The decision to use oxygen at 15 L/min reduces the risk from sepsis, but may present a risk to those with COPD. Decisions in any emergency are based on evidence, experience and not least respiratory medical practices being developed during the COVID crisis.