Partisan Field Care – Casualty Monitoring, by Teddy Bear (D.O.)

Previous Installments from the Guerilla Clinic series:

TAKING VITALS

TAKING A PATIENT HISTORY IN A CLINIC OR SICK VISIT SETTING

PHYSICAL EXAM, PART ONE

PHYSICAL EXAM: PART TWO

David Caldwell Log Cabin School – Virtual

Teddy Bear holds a Doctor of Osteopathy (D.O.) degree, and practices medicine as a general practitioner. As a hobby, Teddy collects various states’ medical licenses. Having entered medical school specifically with a coming collapse in mind, Teddy appreciates the opportunity to educate, viewing it as a form of caching. Teddy Bear trains to protect the innocent from monsters when the lights go out, and hopes you do, too.

Disclaimers: All provided links are for educational purposes or representational examples only.  At the time of this writing, there are no financial associations with any product mentioned or linked.  All products are examples only without personal knowledge of how they perform, except where noted. The following information is for educational and entertainment purposes only, and does not constitute medical advice. If at all possible, always seek out the highest level of appropriate care available to you.

Partisan Field Care:

Casualty monitoring in the patrol base

TCCC is the foundation of addressing life threats such as bleeding and respirations. Assuming that has been done correctly, as a caregiver in austere, non-permissive, environments you will have to sit on a patient far longer than you normally would given their injuries. Therefore it is critical that you regularly and consistently monitor your casualty’s physiological status. If TCCC is a sprint, then we are now into a marathon. You will need to document this data, and MechMedic has the appropriate form (PFC Casualty Card) available for free download here. I recommend you download this form to reference as you follow along. We will be concerning ourselves with the section circled in red.

We covered many of the various tools we have available for this task in the earlier vitals article, or this excellent review by MechMedic. Rather than focusing on tools or techniques, we will build on that knowledge to explore what trending vitals can do for our clinical decision making. In addition to vitals, we will look at additional data we can gather on our patient non-invasively. We don’t want to put holes in the patient’s anti-infection suit, known as skin, unless we have to. As a  preview, we are trending oxygen level, blood pressure, temperature, heart rate, respiratory rate, as well as fluid intake, urine output, and carbon dioxide output. We are assuming a severely injured patient that is either unconscious or sedated, so we are limited to objective measurements.

This index from the casualty card is worth noting. Each value has its own symbol. Respiration rate is an empty circle, pulse is a solid circle, temperature is an X, etc. Notice that this index is constructed in such a way that each measured criteria is close to its normal value on vertical number line. For example, respirations have a gray shaded section that includes the values from 10 to 20. This is approximately the normal range for respirations and is useful way to remind yourself when you’re wet,  cold, tired, hungry, thirsty, and scared, if a casualty’s values are becoming abnormal. As we’ll explore later, the shading system is not 100% accurate, but it serves as a guideline if you don’t have the normal values memorized.

Systolic (v) and Diastolic (^) BP

We will not discuss how to take a BP here. As mentioned, that has been covered elsewhere. For your role as a covert critical care provider, the higher the blood pressure the better, unless your higher medical authority has told you otherwise due to concern for rupturing existing clots or other potential damage from high vascular pressures. Blood pressure trending upward is most likely due to casualty’s pain increasing, which should be addressed appropriately depending on your resources and standing orders from your higher medical authority. If the systolic BP is rising, and pulse pressure is increasing, increased intracranial pressure (IICP) should be considered. Look for pupillary dilatation, decreased heart rate (bradycardia), and abnormal breathing patterns (papilledema is another finding consistent with IICP, and we will discuss how to perform this exam in an upcoming article, but it is unlikely to be feasible for the medic operating out of his ruck). BP trending down is more concerning, since this could be due to a renewed bleeding or a newly presenting bleed, among other things. Start looking for signs of bleeding if the casualty’s BP moves toward being dangerously low. We will cover how to determine when this is during our mean arterial pressure (MAP) discussion. Also, keep in mind that sepsis and neurologic trauma can cause BP to decrease. However, even if one or both of these is a likely cause, you should always evaluate for bleeding in the context of battlefield trauma.

Temperature (X)

On the topic of sepsis, an infection in the bloodstream, trending temperature will give a heads-up that the patient is developing a fever from an infection. Keep in mind, however, that like other causes of shock, septic shock causes a decrease of blood flow to the skin and results in drop in surface temperature in its later stages. So if you have a casualty with an infected wound who was running a fever which suddenly goes away for no reason, you should expect septic shock, especially if there is an accompanying drop in BP.

Percent Saturation of Oxygen [SPO2] (◊)

Oxygen saturation is a good measure of lung function. Lungs and heart are two pump systems that work in tandem. If the heart is not working well, you probably won’t get a measurement of oxygen saturation. However, if you can get a good measurement, it is a reliable value.

Pulse (●)

Also known as heart rate, this value will rise as BP drops when your casualty is going into shock. Under emotional stress or pain, heart rate and BP will both rise. Heart rate trending down could be a sign of increased intracranial pressure (IICP), or hypothermia.

Mean Arterial Pressure [MAP] (Δ)

Since BP has a top number and bottom number that can both vary greatly, a mean (average) BP can give us a more usable metric. Perfusion is the term for getting blood to the tissues where it needs to be, whether that’s the lungs to pick up O2 and dump CO2 or the rest of the body to deliver O2 and pick up CO2. The critical number that we are looking keep our casualty above is 65 (mmHg). To see how this is calculated, let’s think about the heartbeat cycle. With every cycle, the heart relaxes to fill with blood (diastole) and then squeezes to push that blood out (systole) to either the lungs or the periphery (what heart and lung doctors call the rest of the body). During this cycle, the heart spends about 2/3 of the cycle filling, and 1/3 emptying. Therefore we weight our average arterial pressure to reflect this time

End Tidal Carbon Dioxide [ETCO2] (■)

Suppose for a moment that while your casualty’s lungs were functioning fine, their heart was not doing well in pumping blood to the lungs. How would you know? Your pulse oximeter would still read normal for the moment, because it is measuring how much oxygen is bound to the red blood cells, which is a more immediate measurement of lung function, although it would eventually be affected by reduced cardiac output as a backlog of deoxygenated blood circulated back to the periphery. ETCO2 is what gives us that early warning sign that the heart is not working well (tension pneumothorax, anyone?) before our casualty deteriorates further and we have to take drastic actions.

This metric is the amount of carbon dioxide (CO2) breathed out at the end of a normal breath or tidal volume. Typically, CO2 is measured qualitatively (is there or not) rather than quantitatively (how much is there). The qualitative measure is usually done with special kinds of litmus paper that change color when in contact with CO2. Typically, this is done to confirm successful placement of an airway (after we’ve placed a plastic tube into the windpipe). It will start as purple and remain so for CO2 levels <3mmHg, turning tan for values of 3 to 15 mmHg, and yellow for >15mmHg.

These are available for purchase at this link for around $45.

Keep in mind that the normal ranges for EtCO2 are 35 to 45 mmHg, and studies have found that values ≤ 29.5 mmHg “was independently predictive of the need for massive transfusion.” There’s obviously a 15 point gap between the top end of what the litmus paper indicates and that critical value. Thankfully, you have other measurements to help you assess the patient. It does help in determining you calculate whether you think you need to drop the coin on an EMMA versus the litmus paper, though.

The quantitative option, which is superior for our purposes, but also more expensive is called an EMMA by Masimo. This is the least expensive I’ve found them from a retailer, and that was $1300. Keep in mind that the Prolonged Field Care system is military, and they do not have to pay for their own equipment.

Respirations (○)

Blood needs to stay  inside, and air needs to go round and round. How air does this can tell us about the patient’s status. Irregular breathing patterns can be a sign of neurologic trauma, as can very slow breathing. Rapid shallow breathing can be the body trying to correct an acid-base imbalance, which would point to larger underlying issues. If your casualty’s breathing patterns are irregular, take the full minute to count breaths. Also, keep in mind that your casualty may have a preexisting condition called sleep apnea, where their airway becomes blocked by their tongue during sleep. Normally, this individual’s first complaint will be fatigue and daytime drowsiness because their normal sleep cycle is being interrupted. Know as much as you can as the medic about your team’s health histories. Note that while sleep apnea is associated with a thick neck and therefore obesity, individuals with a lot of muscle mass in their neck can have the same problem.

Fluid outputs (Urine)

Assuming an unconscious casualty, you will need to collect urine, both for sanitation as well as monitoring the patient’s vascular status. The kidneys have a large role in blood pressure management, and if they are getting blood, likely all the other internal organs are, as well. If the kidneys are adequately perfused, they should be making at least 0.3 mL/kg or 0.14 mL/lb (1kg = 2.2 lb) per hour, or at least 500 mL/day of urine output. Consider this an average over several hours, so as not to inappropriately intervene for one isolated low number. So, if your casualty is a 200 pound male making an average of 28 mL/hr (just under two tablespoons), you can be reassured that his perfusion is adequate, given adequate hydration. Note: the target rate for crush injuries is as much as ten times this, with hydration rates to match.

Something to consider adding to your supplies for this purpose is the condom catheter. Note that for obvious reasons these will not work for catheterizing females.

Fluid inputs (Oral, IV, etc.)

It is outside the scope of this article to all the various methods of hydration, or the special cases such as burns or crush injury, so we will limit ourselves to the normal parameters for now. Keep in mind that a gallon is 3.8 L, or 3800 mL.

From Sterns, R.  Maintenance and replacement fluid therapy in adults.  In UpToDate, accessed 20 March 2023.

“Normal adults are considered to have a minimal obligatory water intake or generation of approximately 1600 mL per day, composed of the following:

• Ingested water – 500 mL
• Water in food – 800 mL
• Water from oxidation – 300 mL

The sources of obligatory water output in normal adults are composed of the following:

• Urine – 500 mL
• Skin – 500 mL
• Respiratory tract – 400 mL
• Stool – 200 mL

Water requirements increase by 100 to 150 mL/day for each degree of body temperature elevation over 37°C.”

The usual maintenance hydration rates assume no solid food intake.  This would be 100-150mL/hr across 24 hours for adults >50kg (depending on the size and conditions they’ve been exposed to); for <50kg, use the 4-2-1 rule (4mL/hr for the first 10kg, 2mL/hr for the next 10kg, 1mL/hr for everything >20kg, eg, for a 48kg patient, 40+20+28=88mL/hr).  This works for PO hydration, not just IV.  It’s a good target for a conscious patient who can drink, not just for calculating drip rates. Keep in mind that an unconscious patient is not going to be eating or drinking, so you will need to be thinking about how you will keep the casualty hydrated if you are going to be responsible for them for a protracted period.

For a good discussion on non-invasive hemodynamic monitoring, I recommend you look at this video from the College of Remote and Offshore Medicine.

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That wraps up this brief review of the vitals to trend from the Prolonged Field Care Casualty Card. Further articles will be forthcoming on the topic of partisan field care, but for now keep in mind that none of this means a thing if your casualty did not survive the point of injury, so make sure your TCCC skills are well practiced and current. I will be attending the upcoming April 2023 class on TCCC offered by Stuck Pig Medical, and I recommend you consider initiating or refreshing your own training. As always, I have no financial relationship, just my sincere recommendation.

Until next time, this is Teddy Bear, out.