Beyond the Basics: Putting the VITAL Back in Vital Signs

CEU Review Form Beyond the Basics: Beyond the Basics: Putting the Back in VITAL SIGNS (PDF) Valid until November 7, 2008

     Vital signs are important and obtained on every call, yet a sense of routine permeates their gathering. This month's article will help firm up basic skills, identify the role of vital signs in the thinking and decision-making process and cover some additional diagnostic procedures that can be performed.

CASE PRESENTATION
     Your ambulance is called to a syncopal episode at a local community hall. Your patient is an 82-year-old male who responders say acted a bit "spacy" for about a minute and then passed out. A friend who assisted him to the floor described him as being "dead weight." He came to quickly after being placed in a recumbent position.

     You arrive at the patient's side and find the man responsive, breathing adequately and a bit pale with some sweat visible around his face. Family members tell you the patient has had some sort of dementia and is a poor historian of medical complaints and conditions. You are unable to determine if he experienced any signs or symptoms before collapsing. The family wants to know if the patient really needs to go to the hospital because he seems alright now.

     Completing your initial assessment while your partner administers oxygen by nasal cannula, you detect a strong, regular radial pulse at about 88/minute. You note that it is warm in the room.

     His BG is 127; BP 110/72; respirations 20; pulse 88, strong and regular; skin a bit warmer and slightly moist. An EKG shows a normal sinus rhythm without ectopy at 88/minute.

     You decide to sit the patient up and attempt orthostatic vital signs. He denies dizziness when changing position. Blood pressure changes to 98/68; pulse is 92/minute and weak; respirations are 22/minute; and he becomes a bit more diaphoretic.

     This case highlights the most important part of vital signs: correct interpretation. While the change in systolic pressure is a borderline significant reading, many would look at the relatively stable pulse and respirations combined with the lack of lightheadedness and consider this a negative test.

     Experienced clinicians recognize that not every set of vital signs will exactly match the clinical picture of orthostasis, much like patients rarely exhibit all of the signs and symptoms of a disease or condition. In this case, the EMTs on scene recognized the patient's inability to accurately present signs and symptoms. A patient of this age may be on medications like beta blockers, which could depress the sympathetic nervous system's ability to respond during the tilt test.

Looking at vital signs in combination with the overall patient presentation allowed the EMTs to strongly recommend transport to a patient who had considered refusal. Subsequent emergency department evaluation revealed dehydration secondary to poor feeding caused by dementia. The patient was found to be on atenolol, which explained the lackluster orthostatic changes in the tilt test.

RESPIRATIONS
     While pulse and respirations may seem like "grounders" to the experienced provider, it is valuable to review even the most basic skills and look into problem areas.

     Of all the vital signs, respirations may seem the most awkward to obtain because the patient shouldn't be speaking or aware his respirations are being counted. Increased respirations are part of the initial response to compensation for shock and therefore diagnostically significant.

     A persistent problem for advanced and basic providers alike, both in the field and as identified by the National Registry of EMTs as an issue in exams, is identification and appropriate treatment of inadequate breathing.

     When evaluating a patient's breathing, it is critical to evaluate both rate and depth. Without both being adequate, breathing is inadequate. To evaluate depth of breathing, listen for the number of words a patient can speak before having to catch his breath. Watch chest excursion. In some cases (patients with an altered mental status and/or trauma), you will place your hands on the anterior chest bilaterally to feel this excursion. This allows the additional benefit of identifying trauma, including flail segments, that can interfere with adequate breathing.

     Even experienced providers are fooled by patients with rapid respirations. Before reaching for the non-rebreather mask, ensure the breathing is deep enough. Most patients breathing over 40 breaths/minute are either breathing inadequately or will tire and begin inadequate breathing soon.

     The concept behind why breathing must be of an adequate rate and depth is centered around the concept of dead space. Dead space is the area of the respiratory system that doesn't exchange oxygen and carbon dioxide. Dead space air is found in the mouth and trachea and never actually reaches the alveoli, where gas exchange occurs. The amount of air it takes to enter the mouth and travel through the bronchi and bronchioles before reaching the alveoli in the average adult is 150 ml. In short, if the patient is taking shallow breaths, inspired air doesn't reach the alveoli and no gas exchange takes place.

     Consider the respiratory status of the following patients:

PATIENT #1      He is breathing normally at 12 breaths per minute. Each breath is about 500 ml. This means that the patient is breathing in 6,000 ml/minute (his minute volume). Remember that 150 ml of each breath is unusable; 1,800 ml of that air is not used in gas exchange; 4,200 ml is adequate for gas exchange in the alveoli.

PATIENT #2      This patient is breathing 8 times per minute with a decreased tidal volume of 350 ml. She is hypoventilating, and the equation changes dramatically. This patient's minute volume is only 2,800 ml. Once you subtract the dead space (1,200 ml), the patient is only moving 1,600 ml/minute into the alveoli. This patient is breathing inadequately and requires ventilation.

PATIENT #3      The patient who is most commonly misunderstood is the one who is breathing rapidly. This patient, breathing shallowly at 40 times per minute, is also breathing inadequately. The rapid, shallow rate barely makes up for the dead space. At 40 breaths per minute at 200 ml of air/breath, the resulting 8,000 ml/minute volume is deceiving. Subtracting the dead space (40 x 150 ml=6,000), we see that 75% of the inspired air never reaches the alveoli for gas exchange. This patient requires ventilation for inadequate breathing.

     One of the most significant and meaningful interventions by a prehospital provider is to identify inadequate breathing and intervene by ventilating the patient before respiratory arrest develops.

PULSE
     Like respirations, we consider the pulse a simple vital sign. It is generally easy to obtain and we understand its importance. We generally obtain the pulse from a responsive patient at the radial artery and check for a pulse in unresponsive patients at the carotid artery.

     Many providers silently struggle with the math in both pulse and respirations. The answer to 33x4 when kneeling before a patient who is shocky with an altered mental status is certainly challenging, even to those who are mathematically inclined. Accuracy is vital in locating and counting the pulse, as well as the resulting computation.

     The pulse should also be evaluated for regularity and strength. A key reason for this was noted in the case study that began this article. While the patient's pulse did not significantly change in rate, it did become notably weaker when he was moved to an upright position.

     There are other ways the pulse can aid in more advanced diagnosis.

     In a patient with chest pain, discomfort or heaviness, especially if the chest pain appears atypical for myocardial infarction, it is beneficial to check the pulse at both wrists simultaneously. In patients who have an aortic coarctation or aneurysm that is proximal to or affecting the left subclavian artery, radial pulses will be unequal. The pulse is normally felt at the same time when palpating bilaterally. In aneurysm, the left pulse may be delayed, be weaker and have a different feel or character.

     In abdominal aneurysm there may be differences between the radial and lower extremity pulse points, such as the femoral or pedal pulse points. These distal pulses may be notably weaker.

     These signs are valuable in patients who present with pain or hypotension of unknown or suspected intra-abdominal origin. Remember that the symptoms of aneurysm, most notably tearing pain, are not as common and diagnostically reliable as we were once led to believe. Simple and relatively quick examinations like comparing pulses bilaterally and between proximal (carotid) and distal (femoral) points, when correlated to the overall patient picture, can have a high yield.

SKIN
     Skin should be observed in all patients for color, temperature and condition. This will assist in evaluating a variety of conditions, from shock to environmental emergencies to fever. It should be noted that skin temperature is not always an accurate representation of the underlying core body temperature.

     When blood is shunted from the periphery in cases of shock, the result is cool, moist skin. This is an important finding that occurs early in the shock sequence. A patient having cool, moist skin in the absence of environmental conditions that may cause it is generally considered to have a significant underlying condition.

     Even if the skin isn't cool and moist upon examination, a history of having it during an acute onset of other symptoms (e.g., syncope) should lead a clinician to suspect serious underlying pathologies.

     Skin can also be examined for signs of dehydration. Skin turgor, or elasticity, is reduced when patients are dehydrated. This produces a sign called skin tenting, which might not be a reliable sign in geriatric patients because of a normal loss of skin elasticity with aging.

BLOOD PRESSURE
     While this article can't offer remedies for road and diesel noise, there are a few things that even experienced providers can learn and apply for obtaining more accurate blood pressure readings.

     During auscultation or palpation of a blood pressure, it is easy to understand that the pulsatile nature of arterial blood flow is appreciable during systole. As arterial blood flows from the aorta into the distal arterioles, momentum and, ultimately, pressure is low, and the flow through those vessels is less pulsatile and more fluid. This fluid flow of blood beyond the capillary interface explains why a pulse cannot be appreciated in a vein but can in an artery. Two factors that affect blood flow are pressure and resistance. These factors can be represented by the equation below:

     BP (blood pressure) = CO (cardiac output) x SVR (systemic vascular resistance)

     It is important to note that systolic and diastolic pressures do not indicate the work cycle of the heart. Many people have been taught that systolic pressure indicates the work phase of the left ventricle and the diastolic phase indicates the relaxation phase of the left ventricle. Although this is true, there is a more physiologically relevant explanation of systole and diastole.

     Systolic blood pressure should be considered a measure of left ventricular function. During systole, the left ventricle contracts and ejects blood against pressure into the aorta. This pressure is referred to as afterload. Simply put, systole is a measure of blood ejected by the left ventricle.

     Diastolic pressures can be identified as the absence of sound immediately following the last sound heard while auscultating a blood pressure and during the relaxation phase of the heart. It is important to note that a diastolic pressure represents more than just the relaxed phase of the cardiac cycle. Diastole is a direct measure of the degree of vessel constriction. This means that if a patient is compensating for either an abnormally high or abnormally low blood pressure, they may vasoconstrict or vasodilate and the diastolic pressure will be affected. This principle will allow for effectively determining how well a patient may be compensating or not compensating for changes in cardiac output. The difference between systolic and diastolic pressures is referred to as pulse pressure.

     Three of the most significant things a provider can do to ensure accurate blood pressure readings are to remove clothing, choose the proper size cuff and place the cuff properly on the arm.

     While the realities of the street (climate, spinal precautions, etc.) may make clothing removal difficult, taking blood pressure readings over clothing or with bulky or constricting clothing bunched above the cuff can affect the accuracy of your readings.

     The cuff size is important. Even more important, the bladder size within the cuff—and the position of the bladder—are perhaps the most significant factors for accurate blood pressure determination. The cuff should cover approximately 75%–80% of the arm's circumference and should not overlap itself. The bladder should have a width of 40% of the upper arm circumference.

     Blood pressure bladders that are too wide will cause a lower than actual reading, while a bladder too narrow will cause an artificially high reading.

PUPILS
     Pupillary reactions are frequently checked in trauma patients. Pupils will constrict when you shine a light into them. When a light is introduced to one eye, both eyes will respond. In bright environments where the pupils are already constricted, shade the eye to watch for dilation of the pupils to measure reactivity.

     Reactive pupils are generally noted as PEARL (pupils equal and react to light) or PERRL (pupils equal, round and react to light). PERRLA (pupils equal, round, react to light and accommodation) is not routinely checked in the field. Accommodation is checked by asking a patient to shift his focus from a distant point to a near point. This causes a change in shape of the lens (which is difficult to observe in the field). It should also result in constriction of the pupils.

     Anisocoria is a term meaning unequal pupils. As much as 20% of the population has slightly unequal pupils (+/-1mm), while fewer than 10% have noticeably unequal pupils.

Most critical traumatic and central nervous system conditions that cause unequal pupils are associated with an acute complaint, altered mental status and other significant symptoms. Unequal pupils are rarely a presenting problem. If you observe unequal pupils in the absence of other symptoms, ask the patient if he is aware of this condition from prior examinations.

PULSE OXIMETRY
     Many have called pulse oximetry a "sixth vital sign." Until recently, it was unusual for patient care to be changed solely due to pulse oximetry readings. Newer protocols for stroke and myocardial infarction suggest that oxygen be delivered in lower amounts (e.g., by nasal cannula) when the pulse oximetry reading and patient presentation suggest mild hypoxia.

     Pulse oximetry must be used with caution and as one piece of the clinical puzzle. Always consider the patient's outward appearance, including work breathing, perceived respiratory distress, skin color, accessory muscle use and other signs and symptoms when making decisions regarding oxygenation and ventilation.

     The use of pulse oximetry to measure changes in patient condition in response to treatments (oxygen administration, nebulized medications or inhalers) may be valuable.

     Pulse oximetry provides a noninvasive and continuous means of determining arterial oxygen saturation. Pulse oximeters use infrared light to determine hemoglobin saturation. A light is emitted through the pulse oximeter probe and a sensor is placed at the backside of the probe to determine the amount of light that is able to pass through the capillary bed. Hemoglobin without oxygen bound to it or with low concentrations of oxygen will allow more light through the capillaries than will oxygen-saturated hemoglobin.

     Pulse oximeters will overestimate true arterial hemoglobin oxygen saturation in the setting of carbon monoxide toxicity. By understanding how pulse oximetry works, it is easy to understand how carbon monoxide can give a false positive reading. Carbon monoxide has a greater affinity to hemoglobin than oxygen.

     It should be understood that pulse oximetery is not the definitive answer to respiratory assessment. Pulse oximetry should be used as a differential diagnostic tool in conjunction with the patient's clinical presentation. A normal saturation of 97.5% occurs at a PO₂ of 100 mmHg. A decrease in PO₂ to 60 mmHg still allows the hemoglobin to be 90% saturated. The curve is fairly steep in the normal range of systemic venous PO₂ or PvO₂, which allows further unloading of oxygen to tissues, with only small drops in the partial pressures of oxygen. The oxygen unloaded under normal resting conditions leaves a PvO₂ of 40 mmHg and a saturation of 75%.

MENTAL STATUS
     A patient's mental status is not generally considered a vital sign, but its diagnostic potential is so significant that it warrants mention here.

     Altered mental status is an early and reliable indicator of instability and the presence of clinically significant underlying conditions. The brain has a low tolerance for disruptions in oxygen and glucose levels; therefore, decreased levels of these substances—or the blood flow that supplies them—often provides the first warning of serious medical or traumatic conditions.

     Get a sense for the patient's mental status initially using the AVPU scale. Be alert for small changes that could easily be overlooked. A patient who appears uncomfortable, edgy or even cranky may be that way because of hypoxia.

TRENDS IN VITAL SIGNS
     More important than an individual vital sign is a series of vital signs over time. Vitals should be reassessed frequently for patients who are unstable or potentially unstable. Vital signs over time help identify specific medical or traumatic conditions and are a major factor in making appropriate transport decisions.

     The following are commonly identified trends which, when identified, are beneficial to practice:

     Developing shock: increased pulse and respirations; cool, moist skin; anxiety; and eventually a decreased blood pressure with narrowing pulse pressure (the difference between systolic and diastolic readings).

     Anxious patient calming down: At major scenes (e.g., motor vehicle collisions), patients are frequently excited and anxious, causing vital signs that resemble shock (elevated pulse and respirations, anxiety, but an elevated systolic blood pressure in response to stress). The difference in this case is that with oxygen and calming, the patient's pulse and respirations generally decrease. Complicating decision-making for many providers is that the blood pressure will decrease. It is important to look at all vital signs to observe trends. In most cases, what will differentiate this from shock is the decreasing anxiety and leveling of the pulse and respirations. In most cases, skin color, temperature and condition will also be normal.

     Increasing intracranial pressure: The classic triad of increasing intracranial pressure is decreasing pulse, elevated/increasing blood pressure and abnormal breathing patterns. We have chosen not to specify a particular breathing pattern, since it is challenging to actually identify a particular pattern. A change in respiratory pattern is a late sign. As intracranial pressure increases, an altered mental status is an early and reliable sign. Pupil irregularities are also to be expected at later stages of pressure.

     Unconscious patient with hypertension and tachycardia: In an unconscious patient with increasing heart rate and blood pressure, pain should be considered. Because of the normal physiologic response of the baroreceptors, an elevated BP should cause the heart rate to drop; in this scenario, the patient is hypertensive and tachycardic because of a sympathetic pain response.

CONCLUSION
     The intent of this article is to refresh some vital sign basics, as well as highlight the importance of vital signs—and serial vital signs—as the centerpiece of a solid clinical thinking process. While vital signs often become a rote process, it takes work to ensure proper equipment is used to obtain the needed vital signs at the right intervals. By accurately obtaining and recording vital signs, your clinical practice and decision- making will benefit greatly.

CEU Review Form Beyond the Basics: Beyond the Basics: Putting the Back in VITAL SIGNS (PDF) Valid until November 7, 2008

Daniel D. Limmer, AS, EMT-P, is a paramedic with Kennebunk Fire-Rescue in Kennebunk, ME.

Joseph J. Mistovich, Med, NREMT-P, is a professor and chair of the Department of Health Professions at Youngstown (OH) State University.

William S. Krost, MBA, NREMT-P, is director of Emergency Services & Health System Access for Blanchard Valley Health System in Findlay, OH.