Practical Technology for the Technology Enhanced Scenario - and a Physiology Refresher (Part 2)

07/18/2019

By SimGHOSTS Board Member Scott Crawford, MD CHSOS

 

This article will continue a discussions from a previous blog about the use of alternative evaluation techniques for patients presenting in non-traditional environments for medical care. In addition to the previous discussion about wearable technologies, a description of medical equipment and evaluation in public spaces, including airplanes, will highlight the benefit of training or reviewing how to provide evaluation and treatment in these environments using simulation.

 It should be no surprise to those who routinely use simulation for medical training that medical emergencies can happen anywhere there are people to experience them. This is one reason why simulation is used for training in austere or uncommon environments. One not so unlikely environment, as it turns out, is on commercial aircraft.

 A 1999 review of medical emergencies from British Airways suggests that a medical condition occurred on-board in about 1 in every 11,000 passengers (1). In addition to this report it was noted in 2013 that 2.75 billion passengers flew on commercial aircraft annually and that as many as 1 medical emergency in every 604 flights was reported (2). Increased ability to travel by air and an aging population may increase the occurrence of these events (3). Many physicians may have some apprehension about volunteering in these often publicly viewable settings to render aid with unknown and unfamiliar medical equipment/supplies; and the ever-present fear of scrutiny for care rendered. This final consideration of the medico-legal liability and the extent of “Good Samaritan” protection if poor outcomes occur during an attempt to render aid may keep health professionals from putting themselves forward in these situations. It was reported in an international paper describing medical care on aircraft that such Good Samaritan protection does not extend to those offering care aboard an aircraft (3). However, for U.S.-based flights, the 1998 Aviation Medical Assistance Act (4) provides some protection if:

  1. The individual is not an employee of the airline (ie. Does not accept monetary compensation). However, it is noted that vouchers or first-class upgrades may still be allowable (but it may simply be safer to avoid this perception).

2. The individual must give medical care that others with similar training would provide under similar circumstances.

3. This act does not protect against gross negligence or willful misconduct.

 

What can happen in the air?

The most commonly reported incidents from 2008-2010 were (2):

       Syncope/presyncope         (37.4%)

       Respiratory                          (12.1%)

       Nausea/vomiting                (9.5%)

       Cardiac                                 (7.7%)

       Seizure                                  (5.8%)

    

This is a slight change from prior reported events from 1991-1996 (4):

       Cardiac                                  (40%)

       Unconscious (syncope)     (17%)

       Seizure                                  (14%)

       Unknown                             (9%)

       Psychiatric                           (7%)

      

What type of equipment may be available to those providing medical care?

 The Federal Aviation Administration provided the following information about available medical kits in 2006. This kit is required to be carried by aircraft carrying more than 30 passengers, with at least one flight attendant (5).

 

Contents

QTY

Sphygmomanometer

1

Stethoscope

1

Airways, oropharyngeal (3 sizes): 1 pediatric, 1 small adult, 1 large adult or equivalent

3

Self-inflating manual resuscitation device with 3 masks (1 pediatric, 1 small adult, 1 large adult or equivalent)

1:

3 masks

CPR mask (3 sizes): 1 pediatric, 1 small adult, 1 large adult, or equivalent

3

IV Admin Set: Tubing w/ 2 Y connectors

1

Alcohol sponges

2

Adhesive tape, 1-inch standard roll adhesive

1

Tape scissors

1 pair

Tourniquet

1

Saline solution, 500 cc

1

Protective nonpermeable gloves or equivalent

1 pair

Needles (2-18 ga., 2-20 ga., 2-22 ga., or sizes necessary to administer required medications)

6

Syringes (1-5 cc, 2-10 cc, or sizes necessary to administer required medications)

4

Analgesic, non-narcotic, tablets, 325 mg

4

Antihistamine tablets, 25 mg

4

Antihistamine injectable, 50 mg, (single dose ampule or equivalent)

2

Atropine, 0.5 mg, 5 cc (single dose ampule or equivalent)

2

Aspirin tablets, 325 mg

4

Bronchodilator, inhaled (metered dose inhaler or equivalent)

1

Dextrose, 50%/50 cc injectable (single dose ampule or equivalent)

1

Epinephrine 1:1000, 1 cc, injectable (single dose ampule or equivalent)

2

Epinephrine 1:10,000, 2 cc, injectable (single dose ampule or equivalent)

2

Lidocaine, 5 cc, 20 mg/ml, injectable (single dose ampule or equivalent)

2

Nitroglycerine tablets, 0.4 mg

10

Basic instructions for use of the drugs in the kit

1

 

Rendering care with unfamiliar equipment

Just as walking into a simulation room with unclear expectations or limited orientation can inhibit an individual’s ability to focus on patient centered care, this can be similarly disorienting in unfamiliar medical environments. Providing or reviewing training using potential supplies may help medical professionals feel more at ease with these potential circumstances.

 

Blood pressure review

Blood pressure has two numbers, systolic and diastolic. The systolic blood pressure is the highest pressure produced by the heart during cardiac contraction; the diastolic pressure is the pressure still present in the arterial system during cardiac relaxation. These pressures are measured using a pneumatic cuff (sphygmomanometer) that is inflated around an extremity until the flow of blood is stopped completely. The pressure is then slowly released while checking for blood flow distally (toward the farthest part of an extremity). The pressure at which flow begins, during cardiac contraction, is the systolic pressure. This pressure is identified by listening for turbulent flow past the inflated cuff (Korotkoff sound). The pressure in the cuff at which flow is no longer occluded at any point during the cardiac cycle is the diastolic pressure; ie. the pressure when the sound of turbulent flow is heard for the final time is the diastolic pressure. A ‘normal’ blood pressure (BP) that is not hypertensive is 100-139 mmHg (systolic)/60-89 mmHg (diastolic). Elevated blood pressure is one of the most common medical conditions experienced by patients. Long-term it can lead to problems with coronary artery disease, stroke and organ injury, especially the kidneys (6). More dangerous immediately, however, is hypotension, or low blood pressure. This condition usually indicates problems with the heart, loss of blood volume (dehydration or hemorrhage), or severe infection (sepsis).

 

Patient care examples:

 “Is there a doctor on board?”

Shortly after graduating from residency as an emergency medicine physician, I saw several flight attendants paying attention to a passenger a few rows in front of me on a domestic flight. Soon, an overhead announcement requested any medically trained passengers aboard to make themselves known by pressing the flight attendant call button. Without considering any of the information presented in the introduction of this article, I pressed my button. I was soon escorted to the middle of the aircraft where a pale woman in her 60s was seated on the aisle. After verbally identifying myself as a doctor the flight crew confidently thrust a sphygmomanometer and stethoscope into my hands and stood dutifully awaiting my report of the vital signs for the passenger. While asking a few quick questions about medical history and conditions I confidently inflated the blood pressure cuff and placed the stethoscope (that I am now confident was manufactured by Fisher-Price) onto the patient’s arm, only to be greeted by a low and persistent “WHIRRRR” from the plane’s engine. After inflating the cuff 3 times and straining to hear the sound, it became clear I would not in fact be able to identify the soft “whoosh” that would normally mark the beginning and end of flow occlusion by the blood pressure cuff. This is an experience quite normal for paramedics and pre-hospital care providers who work in loud or noisy environments such as the back of an ambulance. Instead, the only method for getting a blood pressure in these environments is by palpating the pulse of the patient distally and then identifying the pressure at which the pulse goes away (systolic pressure). This is recorded as a single BP reading followed by the letter “P” for palp (or palpation). This is actually just as useful for quick patient assessment as the two-number system. If this number is low (less than 100), low blood pressure may be contributing to the symptoms. Fortunately, in my case the patient started to feel well and had no concerning vital signs or symptoms and the flight continued uneventfully. Other more drastic experiences could be those of presentations consistent with stroke or heart attack where a volunteer medical professional may be asked to decide whether to land a craft early or divert after discussing with the airline medical support on the ground.

 

“I’m feeling weak”

 This past spring while watching an outdoor school play in El Paso, TX, a teacher came to ask my assistance in evaluating a woman who was weak and could not stand. Again, a woman in her fifties, wearing all black, and appearing pale in complexion was seen seated to the side of the stage. She had been outside shooting photos of the event for the past 3 hours and became light headed and nearly collapsed. After getting a brief medical history and review of preceding events, I thought it important to check the pulse of the patient as a marker for hydration and cardiac status. I again confidently placed my fingers on the woman’s wrist and pressed down lightly. After feeling nothing, I repositioned; still nothing. I tried the other arm; nothing there either. Again, with a small audience forming and wearing a T-shirt that had a graphical image of a stethoscope, I was unable to feel the pulse of the woman. Slight panic as the differential of possibilities went through my head – No pulse. She’s dead! Start compressions! – was my first thought; but then realized the woman who was sitting up and talking to me, although pale, may not appreciate this drastic next step. Severe cardiac arrythmia? Possibly. Hypoglycemia? Not diabetic, but possible. Dehydration and low blood pressure; also a possibility, but how can I check? The iron-on stethoscope decal from my shirt was of no use for cardiac evaluation.

 I tried to use the light-based pulse monitor from a fitness watch on the patient’s wrist but using it found no identifiable heart rate. I next tried the light-based pulse sensor, using the LED light and camera on my smartphone on her finger. The patient’s pulse was similarly not detected. In patients with very low blood pressure it is possible for the pulse not to be detected at sites far away from the heart. Pre-hospital care providers have an advantage in training here. It is commonly taught that if a pulse is found at the feet, the BP is at least 100 systolic; at the wrist – >80. The femoral pulse can be felt with a systolic pressure as low as 70, and carotid at 60. While this has come into question for specific accuracy, the concept that feeling a pulse at sites further from the heart is real (7). 

It is no surprise, in retrospect, that all of these electronic devices could not find a pulse waveform because in fact the blood pressure was not high enough for a pulse to be present at the wrist or finger of the patient. A similar limitation is encountered with pulse oximeters in patients presenting to the hospital with low blood pressure. While preparing to call EMS for evaluation of the awake, but apparently pulseless patient, I borrowed an Apple Watch from a passerby. Using this device, I was able to find a remarkably normal cardiac rhythm with a rate in the upper 90s. This device does not use light or illumination to “see” blood pulsating in the capillaries of the wearer, but actually measures the small electrical current generated by the heart. This electrical signal is transmitted from the wrist of the wearer to the finger of the opposing hand when it is touching the side of the watch. A true 1-lead electrocardiogram! 20 minutes after consuming 3 cups of water and moving out of the heat, the patient’s pulse magically returned to her wrist – a marker that her dehydration and hypovolemic (low blood volume) induced hypotension had been reversed and blood pressure was at least 90 mmHg.

Images: Top - A Fitbit wearable heart rate monitor showing the lit green LED light used to allow pulse detection and heart rate measurement by its wearer. Bottom - An Apple Watch heart rate monitor activated by contact of finger of opposing hand. 

Application to simulation

The ability to stage specific aspects of patient evaluation makes simulation invaluable in training critical thinking by care providers. All too often learners spend their time staring at the vital signs monitor above the manikin’s head. Using some of the above case examples, you could design a scenario that would reinforce concepts of cardiac output, patient assessment and evaluation in uncommon or austere conditions, helping learners answer the questions: How would you evaluate or assess the severity of this patient’s condition? What tools could you think of to provide assistance with the equipment available on board an aircraft, or at a park? Understanding the underlying physiology and specific function/limitations of both standard medical examination equipment and newer electronic and wearable devices will improve the use and utility of these tools as an alternative evaluation option for those who become patients in unconventional locations.

 

References:

[1] Dowdall N. “Is there a doctor on the aircraft?” Top 10 in-flight medical emergencies. BMJ: British Medical Journal. 2000;321:1336.

[2] Peterson DC, Martin-Gill C, Guyette FX, et al. Outcomes of medical emergencies on commercial airline flights. New England Journal of Medicine. 2013;368:2075-83.

[3] Lateef F, Tay C, Nimbkar N. Is there a doctor on-board?: medical liability during in-flight emergencies. Hong Kong Journal of Emergency Medicine. 2003;10:191-6.

[4] Committee on Transportation and Infrastructure. Aviation Medical Assistance Act. 1998.

[5] Federal Aviation Administration. Emergency Medical Equipment.  Advisory Circular2006.

[6] Chobanian AV, Bakris GL, Black HR, et al. The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure: the JNC 7 report. Jama. 2003;289:2560-71.

[7] Deakin CD, Low JL. Accuracy of the advanced trauma life support guidelines for predicting systolic blood pressure using carotid, femoral, and radial pulses: observational study. Bmj. 2000;321:673-4.