[2010] 1.2.3.3 Do not routinely administer oxygen, but monitor oxygen saturation using pulse oximetry as soon as possible, ideally before hospital admission. Only offer supplemental oxygen to: people with oxygen saturation (SpO2) of less than 94% who are not at risk of hypercapnic respiratory failure, aiming for SpO2 of 94% to 98% people with chronic obstructive pulmonary disease who are at risk of hypercapnic respiratory failure, to achieve a target SpO2 of 88% to 92% until blood gas analysis is available. [2010] Be aware that some pulse oximeters can underestimate or overestimate oxygen saturation levels, especially if the saturation level is borderline. Overestimation has been reported in people with dark skin. See also the NHS England Patient Safety Alert on the risk of harm from inappropriate placement of pulse oximeter probes. 1.2.3.4 Monitor people with acute chest pain, using clinical judgement to decide how often this should be done, until a firm diagnosis is made. This should include: exacerbations of pain and/or other symptoms pulse and blood pressure heart rhythm oxygen saturation by pulse oximetry repeated resting 12-lead ECGs and checking pain relief is effective. [2010] 1.2.3.5 Manage other therapeutic interventions using the NICE guideline on acute coronary syndromes. [2010] 1.2.4 Assessment in hospital for people with a suspected acute coronary syndrome 1.2.4.1 Take a resting 12-lead ECG and a blood sample for high-sensitivity troponin I or T measurement (see the section on use of biochemical markers for diagnosis of an acute coronary syndrome) on arrival in 1.2.4.2 Carry out a physical examination to determine: haemodynamic status signs of complications, for example, pulmonary oedema, cardiogenic shock and signs of non-coronary causes of acute chest pain, such as aortic dissection. 