According to a PubMed article dated Apr 24 2015, odds of ROSC decrease by 4% for every 1 hour delay between call receipt and vasopressor administration. Data was obtained from recent retrospective studies involving 1,122 patients who experienced out-of-hospital cardiac arrest. 544 patients, or 48.3%, experienced ROSC when vasopressors were administered within 10 minutes of arrest. ROSC was more associated with shockable rhythms than PEA and/or asystole. Large prospective studies are in need.

Oxyhemoglobin Dissociation Curve

Albany Medical Center: Emergency Department Orientation Day #1, 2001, Respiratory & Pulmonary Pathophysiological Concepts & Etiological Management. Or, as I like to call it, "The day my clinical practice evolved!"

In addition to the typical topics & concepts presented to the nursing staff by Respiratory Therapists, our class was presented with a topic completely foreign to me, and I'll bet approximately 99% of my peers had never been 'exposed' to this concept as well. What could be so life-altering for an experienced Intensive Care Unit Registered Nurse going from one tertiary care center/level 1 trauma center to another high-volume/high-acuity facility? Which concept, when presented by one of the most intelligently educated and under-utilized health care professionals has the potential to make  so many 'other' seemingly basic concepts suddenly 'make sense' and 'Mind = Blow' at the same time?

How many providers, typically nurses, have been received and transcribed the following order: "Titrate O2 to maintain SpO2 > 93%."  I've always thought, "What an odd order? Kind of random percentage? What's so special about 93%" Nursing staff would always joke about which resident or attending was 'reading articles' because they'd write some unusual or non-typical orders, maybe medication orders, or diagnostic orders, etc.

So why should a patient's SpO2 be 93% or greater? It has to do something known at the Oxyhemoglobin Dissociation Curve, or ODC. Anyone that knows me, or has sat through any of my lectures or training, knows that I include the ODC in every topic, to me, it is that prolific! That important. That integral to effectively managing critically ill patients. To sum it up, the ODC represents hemoglobin's affinity for oxygen. Sounds simple, right? It is, but it's implications are far-reaching and clinical significant and applicable on a large-scale. Below is one picture representation of the ODC.

The ODC basically describes how the hemoglobin molecule binds or releases O2 to the lungs and then tissues. Several factors affect how oxygen interacts with hemoglobin, specifically: Temperature, 2,3 DPG, & H+ ions, or CO2. Changes in these factors affect 1) if there is a net change in direction, & 2) which direction the curve moves; either to the Right or Left. Additionally, two effects, the Haldane Effect & Bohr Effect also influence the curve. Both effects can be confusing and are related intrinsically.

The simplest way to differentiate the two effects is to identify which molecule is the cause of the change. The Haldane effect describes how oxygen concentrations determine hemoglobin's affinity for carbon dioxide. For example, high oxygen concentrations enhance the unloading of carbon dioxide. The converse is also true: low oxygen concentrations promote loading of carbon dioxide onto hemoglobin. In both situations, it is oxygen that causes the change in carbon dioxide levels. The Bohr effect, on the other hand, describes how carbon dioxide and H+ affect the affinity of hemoglobin for oxygen. High CO2 and H+ concentrations cause decreases in affinity for oxygen, while low concentrations cause high affinity for oxygen. To further illustrate the difference, it might help to look at specific examples. In the lungs, when hemoglobin loaded with carbon dioxide is exposed to high oxygen levels, hemoglobin's affinity for carbon dioxide decreases. This is an example of the Haldane effect. In active muscles, carbon dioxide and H+ levels are high. Oxygenated blood that flows past is affected by these conditions, and the affinity of hemoglobin for oxygen is decreased, allowing oxygen to be transferred to the tissues. Because we are looking at the situation from the perspective of carbon dioxide changing oxygen affinity, this is an example of the Bohr effect.

End of Part 1

Trauma Discussion:

A patient with blunt cardiac injury after a MVC is dyspneic, confused, and cyanotic. 2 hours after ICU admission, the patient's blood pressure has 'dropped' and the patient is exhibiting jugular venous distention, or JVD. What is the most likely cause of these findings?

A. Cardiogenic Shock
B. Pulmonary Edema
C. Hypovolemia
D. Cardiac Tamponade

Congratulations to all the EMT's & Paramedics who passed their practical stations last week. And Good Luck to them sitting for their written exam on Thursday!

Recent clinical case: pH < 6.5! EtCO2 9!

A patient was transported to the local community hospital ED in overt respiratory distress. The most significant clinical finding was hyperventilation with LARGE tidal volumes and an EtCO2 of 9 with appropriate waveform. Patient reports a COPD pmhx. The ALS provider does not believe this is COPD-related. The provider was also baffled by the EtCO2, never seeing a value that out of normal range, despite a normal waveform.

Having transported a similar patient interfacility myself, I suspected a certain 'culprit.' Question: What etiology could lower a patient's pH that significantly, that quickly? Discuss the patients 'large' tidal volumes, minute ventilation, her pH, and resulting EtCO2. For an adult, a pH of 6.5 is incompatible with life. She was subsequently intubated by the ED physician and transferred to tertiary care.

Thoughts?

NYS EMT Practical

Good luck to all the New York State EMT & Paramedic students 'sitting' for their practical skills stations today!

New CPR Guidelines in Providence

30 Minute CPR?

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