Guerilla Clinic Basics – Assessing Vitals, by Teddy Bear (D.O.)

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 state’s 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.

First things first: Vitals (BP, HR, RR, SpO2, temperature, mental status)

Vital signs are literally that, objective measurable indicators of human physiology as a whole. They are not subjective symptoms, as they are not information that the patient reports to us. There are three core topics that vital signs give us information about, blood (fluid), the heart/lung pair (pump), and blood vessels (pipes). We will look at each vital sign to see what they can offer us from these three perspectives.

Blood Pressure

Blood pressure (BP) is what many of us think of first when the terms “vitals” comes up. BP is simple a measurement in millimeters of mercury (mmHg) of pressure exerted by the heart on an artery (carrying blood away from the heart to the tissues) when the heart is at the strongest squeeze (systole) during its beat and when it is at its most relaxed between beats (diastole). By convention, systolic BP is recorded to the left or above a separating line, and diastolic BP is recorded to the right or below that same line. (e.g. 120/80, systolic of 120 mmHg, and diastolic of 80 mmHg). While values above 120/80 are considered abnormal, pressures associated with emergencies such as heart attacks and strokes are associated with values at or above 180/120. At the other extreme, excessively low BP can cause vital organs to not get enough blood (poor perfusion), which can result in organ and tissue damage, coma, and eventually death.

Critical care providers, who work in intensive care with the sickest patients, will often use mean arterial pressure (MAP) and a way approximate the perfusion pressures their patients have.  Calculation: MAP = [systolic BP + (2 x diastolic BP)]/3.   Example: the MAP of 120/80 BP would be [120 + (2×80)]/3 = [120 + 160]/3 = 280/3 = 90.33 mmHg. This MAP is well above the target of 65 mmHg that is essential for life functions. Another tool is called Shock Index, which is HR/SBP. So if our normal vitals are 60 and 120/80, the Shock Index is 60/120 = 0.5. What becomes concerning is when HR is equal or greater than SBP, and is 1.0 or more.

Heart Rate and Rhythm

Heart rate (HR) is the number of contraction/relaxation cycles or “beats” the heart performs per minute (beats per minute = BPM). While the most common HR is between 60-100 BPM, trained athletes can be as low as the 40s. For most people, a resting HR this low would be called bradycardia, and may be cause for concern. Also concerning would be a person with a resting HR >100, called tachycardia.

Heart rhythm refers to how regularly the heart beats rather than simply how fast, with an irregular beat being called an arrhythmia. Irregular heart rhythms can be regularly irregular, following a predictable pattern, and irregularly irregular, seemingly random. An irregular heart rhythm can be either stable (the patient lives perfectly well with it) or unstable (erratic or causing symptoms in the patient).  Unstable rhythms can devolve into more serious arrhythmias where there is not enough organized electrical activity in the heart to cause it to beat, termed cardiac arrest. This disruption in electrical activity is distinct from a myocardial infarction (MI, commonly known as a heart attack), when blood supply to heart muscle is interrupted. Keep in mind that an MI causes damage that can lead to an arrhythmia and cardiac arrest, but is not an arrhythmia/cardiac arrest by itself.

As a general rule, the body compensates for a drop in BP, whether due to illness (e.g. sepsis) or a simple change in posture (e.g. standing up quickly from a seated position), with an increase in HR. Thus, a low BP and elevated HR in an ill or injured patient is a sign that the body is compensating for some problem such as loss of blood, dehydration, infection of the bloodstream (sepsis), or even trauma to the brain.

Respiratory Rate and Rhythm (RR)

Respiratory rate is the measure of how many breaths per minute the patient takes. Normally, adults have 12 to 20 breaths per minute (up to 44 in young infants) in a quiet, regular pattern with no sign of struggling to breathe. Rhythm, again, refers to how evenly the breaths are spaced. Chest excursion refers to how much the ribs and sternum move in and out and symmetry refers to if each side of the chest moves the same way.

Tachypnea is abnormally rapid breathing with >20 breaths per minute in adolescents or adults. It can be caused by asthma, salicylate poisoning, pain, and more. Rapid, deep breathing (hyperventilation) can be a result of anxiety, metabolic acidosis, or brain stem injury.

Bradypnea is slow breathing rate <14 per minute can be caused by diabetic acidosis as well as drugs such as opioids. Note: Ketamine does not do this, which is why it a favorite of SOF medics. At the time of this writing, late 2022/early 2023, it has limited availability online due to supply chain disruption. No doubt the war in eastern Europe contributes to this shortage. When it is available, readers with a medical license and a DEA number can order it, as it is a Schedule III drug.

When a patient is having difficulty breathing, several things can be observed. For infants and young children, the sides of the nose flaring in and out, the throat pulling in, and muscles between ribs pulling in (retractions) are strong indicators, regardless of their respiratory rate or rhythm.  In adolescents and adults, retractions still occur, along with the sensation of inability to get enough air, difficulty breathing while lying flat, or sitting leaning forward (tripoding).

Saturation percent oxygen (SpO2)

SpO2 measures the amount of oxygen being carried by the red blood cells available. While in hospital and intensive care settings, blood oxygen levels may be measured directly via drawing blood as part of an arterial blood gas (ABG), oxygen level is usually indirectly measured in a noninvasive fashion using a pulse oximeter. As the name implies, it measures HR and percent of saturation of oxygen. Hemoglobin is the protein that actually carries the oxygen you breath in to your tissues, and subsequently carries the carbon dioxide (CO2) that you produce to your lungs to be expelled from your body. Hemoglobin requires a small amount of iron to work correctly, which is one reason some people need to supplement iron if they don’t get in their diets.

Please note, the pulse oximeter is limited in that it is not measuring oxygen levels directly, but rather is a close approximation of how much of the binding sites of hemoglobin molecules are occupied. This is problematic in patients who are exposed to carbon monoxide (CO) such as in house fires or from running internal combustion engines in enclosed spaces. While these patients will likely have normal pulse oximeter readings (>94%), their hemoglobin is actually saturated with CO, and the patient’s tissues are suffocating. Since the CO is outcompeting the O2 for seats in this molecular game of musical chairs, we have to cheat by providing the patient with lots of supplemental oxygen.

Incidentally, cyanide poisoning works on the same principle as CO poisoning by outcompeting oxygen for a seat on the hemoglobin. Cyanide binds much more tightly to hemoglobin than O2, CO2 or CO, so it is not as easy treat. There has been some teaching in the military medicine world of treating victims of cyanide with hydroxycobalamin (Vitamin B12a), allowing the cyano group to bind to it and form cyanocobalamin, otherwise known as Vitamin B12. Unfortunately, hydroxycobalamin is only available in the United States as a prescription drug at the time of this writing (A.D. 2023). For readers with a medical license (DO, MD, NP, PA), it is available at ~75USD for a 30ml vial from HenrySchein.com.

Temperature

Our bodies break down foodstuffs for energy and nutrients, and a by-product of this is heat. From chemical perspective, this would be considered “waste heat” as energy is not transferred 100% from one set of molecular bonds to another. However, since our normal physiology occurs withing a fairly narrow temperature range, this heat serves the purpose of keeping bodies at this optimal temperature.

As most of us probably already know, the textbook answer for normal body temperature is 98.6 Fahrenheit (37 Celcius/Centigrade), as measured with an oral thermometer. Temperatures vary from the standard under the tongue depending where else it is measured. Rectal is higher by 0.9 F (0.5 C); armpit (axillary) is lower by 1 C; ear (tympanic) is higher by about 0.8 C.  Temporal (forehead) are more variable.  Both oral and rectal are considered core temperatures.

A true fever is considered to be a core body temperature >100.4 F; extreme, dangerously high temperatures (hyperpyrexia) that need immediate attention for cooling are >106 F (41.1 C). Causes of fever are most commonly thought of as infection, but are also caused by trauma (surgery, crush injuries), cancer, hemolytic anemia, certain drug reactions, and immune disorders such as collagen vascular disease (lupus, temporal arteritis, et cetera . . . ).

Temperatures between 95 F-100.4 F are considered within normal ranges and need not generally be  acted upon.

Hypothermia is defined as <95 F (35 C) rectally. Of course, the leading cause is cold exposure, but other causes include sepsis, excess alcohol, starvation, low thyroid function, hypoglycemia (low blood sugar), and reduced movement from paralysis.

Note that the elderly, immune compromised, and chronically ill are less likely to mount a fever response to infection.

Mental Status

Mental status is not thought of as a vital sign, but it represents the totality of fluid, pump, and pipes working as a whole. The brain thinks it is most important, and will prioritize its own well-being. A healthy mental status is “alert and oriented times three” (A/Ox3). “Alert” is exactly how it sounds; aware of one’s surroundings and able to communicate that alertness through some appreciable means, e.g. speaking, eye movement, following commands. “Oriented times three” refers to whether they can demonstrate correct knowledge of who they themselves are (name), where they are (place), and when they are (time). Some allowances can be made for less specific answers on place and time if they have previously been unconscious, but they should be able to give some kind of accurate, if imprecise, response.

In addition to alert, there are 4 other formalized levels of consciousness.

• Lethargy: Drowsy but opens eyes to loud voice, responds to questions, then falls asleep (adolescents and adults). Minimally responsive to commands (children).  Difficult to awaken (toddlers and infants).
• Obtundation: opens eyes to tactile (touch) stimulation and looks at you but responds slowly and appears confused.
• Stupor: rousable only to pain. Verbal responses slow or absent. Lapses back when painful stimulation is removed.
• Coma: Unarousable to any stimulation

AVPU is a very common, more streamlined scale:

• Alert
• Responds to Verbal stimulation (will follow commands such as “squeeze my fingers”); equivalent to obtundation
• Responds to Painful stimulation (blinks or moans when eyelashes are flicked or sternum is rubbed); equivalent to stupor
• Unresponsive (has no change with painful stimulation); equivalent to coma

Tool Resources:

Financial disclaimer: 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.

BP cuff

Cuffs (order one of each except for 11 (adult) since it comes with one): https://www.integrisequipment.com/products/welch-allyn-flexiport-reusable-blood-pressure-cuff?variant=32538902659203

A less expensive option:

https://www.allheart.com/3m-littmann/classic-stethoscopes-by-3m-littmann/unisex/classic-iii-stethoscope-prestige-sphygmomanometer-kit/littkit34.html

Least expensive option:

https://store.doomandbloom.net/blood-pressure-cuff-and-stethoscope-set/

Stethoscope

(See above for less and least expensive options)

https://www.allheart.com/3m-littmann/cardiology-stethoscopes-by-3m-littmann/unisex/cardiology-iv-27-diagnostic-stethoscope/littciv6.html

SpO2 monitor

https://www.allheart.com/american-diagnostic-corporation/american-diagnostic-corporation/unisex/diagnostix-2100-fingertip-pulse-oximeter/adc-2100.html

When purchasing a pulse oximeter, look for one that graphs the waveform of the pulse. The width of this waveform can give you an indicator of the patient’s hemodynamic status. For example, the wider and shorter the waveform the weaker the pulse and more likely the patient hypovolemic due to either blood or some other fluid loss. For more on this topic, consider this video lecture from the College of Remote and Offshore Medicine (COROM).

<https://www.youtube.com/watch?v=SnxCuPl6ktQ&t=838s>

Thermometer

Oral: https://store.doomandbloom.net/oral-thermometer/

Rectal: the above oral thermometer type can be used rectally. It is strongly recommended you label them clearly and do not use them interchangeably. For both and oral and rectal, sterilize between uses.

If you would like to learn how to use these tools in person, consider coming out to a class with Stuck Pig Medical. I have been more than pleased with my experience as a student in virtual classes with MechMedic, and am looking forward to assisting with the upcoming field sanitation and clinical skills class in June. Hope to see you there. (I have no financial relationship to disclose.)

Registration is available at this link: