Reliability of blood color and blood gases in discriminating arterial from venous puncture during cardiopulmonary resuscitation

Benefits, key protocol components, and considerations for successful implementation of extracorporeal cardiopulmonary resuscitation: a review of the recent literature

The application of venoarterial extracorporeal membrane oxygenation (ECMO) in patients unresponsive to conventional cardiopulmonary resuscitation (CPR) has significantly increased in recent years. To date, three published randomized trials have investigated the use of extracorporeal CPR (ECPR) in adults with refractory out-of-hospital cardiac arrest. Although these trials reported inconsistent results, they suggest that ECPR may have a significant survival benefit over conventional CPR in selected patients only when performed with strict protocol adherence in experienced emergency medical services-hospital systems. Several studies suggest that identifying suitable ECPR candidates and reducing the time from cardiac arrest to ECMO initiation are key to successful outcomes. Prehospital ECPR or the rendezvous approach may allow more patients to receive ECPR within acceptable timeframes than ECPR initiation on arrival at a capable hospital. ECPR is only one part of the system of care for resuscitation of cardiac arrest victims. Optimizing the chain of survival is critical to improving outcomes of patients receiving ECPR. Further studies are needed to find the optimal strategy for the use of ECPR.

Use of blood colour for assessment of arterial oxygen saturation in immobilized impala (Aepyceros melampus)

OBJECTIVE

To determine the relationship between arterial blood colour [as defined by the International Commission on Illumination (CIE) L∗a∗b∗ colour space] and haemoglobin oxygen saturation [functional saturation (SaO₂) and fractional saturation (FO₂Hb)], and if arterial blood colour can be used to predict arterial haemoglobin oxygen saturation.

STUDY DESIGN

Descriptive study as an adjunct to two prospective randomized crossover studies.

ANIMALS

A group of 10 wild caught adult female impala (Aepyceros melampus) weighing 34.1 ± 5.2 kg (mean ± standard deviation).

METHODS

Impala were immobilized with potent opioids (0.09 mg kg^-1 of etorphine or thiafentanil). A total of 163 arterial blood samples were collected anaerobically into heparinized syringes from arterial cannulae and analysed immediately using spectrocolourimetry and co-oximetry. Data were analysed by modelling the relationship between predicted arterial blood colour CIE L∗a∗b∗ components and SaO₂ and FO₂Hb. The models were then used to predict values for L∗, a∗ and b∗ to produce a colour palette for the range of SaO₂ and FO₂Hb used. The modified version of the Farnsworth-Munsell hue test was used to assess the subjective ordering of the resulting colour palette by 20 observers.

RESULTS

The second-order polynomial (quadratic) model produced the best fit for all three arterial blood colour CIE L∗a∗b∗ components for both SaO₂ and FO₂Hb. The regression models were used to generate predicted arterial blood colour CIE L∗a∗b∗ components for the midpoint of each decile over a range of SaO₂ and FO₂Hb percentages (15% to 95%). The resulting colour palettes were correctly ordered by all observers in the SaO₂ range of 45-95% saturation.

CONCLUSIONS AND CLINICAL RELEVANCE

An association between arterial blood colour (as defined by CIE L∗a∗b∗ components) and SaO₂ and FO₂Hb exists, and arterial blood colour can be used to give a clinically useful estimate of arterial haemoglobin oxygen saturation in impala.