A trauma surgeon was recently involved in a case where stress affected his ability to perform a tracheotomy. The case involved a tactical team officer, who was brought to the ED with a gunshot wound that required an emergency tracheotomy. The surgeon knew the officer well, knew the members of his tactical team and had actually trained with the team on many occasions as their emergency team doctor. Therefore, a special bond existed between them.

The officer’s wounds were serious, and his fellow officers refused to leave his side. As the surgeon began what should have been a simple procedure, his vision became distorted and his hands became sweaty and shook, resulting in his inability to firmly grasp the surgical tool. A simple straight-line incision took several attempts, leading to what he described as a “road map” of scars.

In the end, the surgeon saved the officer’s life. The officer recovered and is again active on the tactical team. But the surgeon confessed to me that the stress associated with the seriousness of the injury, his personal association with the officer, and the peer pressure from the patient’s team members impacted his visual clarity, his ability to concentrate and his precision motor skills.

Prior to this event, the surgeon had performed dozens of the same procedures in a variety of conditions with absolute precision. So what went wrong?

Operational Characteristics
There’s a saying, “To err is human.” I propose that “error is subsequent to the human factor.” In EMS, human factors collide with the need to decide quickly and act precisely, under conditions that are dynamic, stress-inducing and occasionally hostile. The key to ensuring effective performance under those conditions lies in understanding the body’s response to stress and danger.

Consider for a moment the basic operational parameters of the emergency medical professional:

  • The mission of EMS professionals is to provide care and save lives.
  • They operate in environments that are dynamic, unstable, time-sensitive and at times hostile to their safety.
  • They work under the stress that is multi-dimensional—ranging from self-induced stress, peer-based stress, patient stress and bystander stress—and magnified by the need to treat/save the patient.
  • They are required to exhibit absolute precision—in perception, diagnosis, treatment (precise motor skills), communications (to fellow operators and the patient) and patient protection.
  • They are constantly exposed to spontaneous and unexpected threats that can trigger their startle response.

Very few professions operate in extreme environments that also require precise skills; even fewer have the added stress of saving lives as their core mission. In fact, from the perspective of basic human physiology, the EMS professional’s mission is a scientific paradox: the operational environment is extremely dynamic and often life-threatening to the operator; but the operational requirement is extreme precision—the precision required when threading a needle, only there’s a life on the line.

The focus of this article is the role of the sympathetic nervous system (SNS) as it relates to the mission, operational environment and operational requirements of the emergency medical professional. My goal is to educate emergency personnel on the hard-wired mechanics of the body’s stress physiology circuitry and how it impacts precision skills, from complex medical procedures to such basic acts as opening medical kits and supplies.

Identification of Stress Symptoms
Emergency medical professionals can experience various predictable EMS stressors, such as:

  • Self-induced stress to save a life
  • Time constraints
  • Colleagues’ presence
  • Dynamic and unstable environment (terrain, weather, crowds, etc.)
  • Patient’s psychological state (scared, irritated, angry or combative)
  • Third parties (family, friends or bystanders)
  • Poorly designed equipment
  • Failure to perform a skill correctly the first time
  • Threat to the operator from a third party or environmental conditions

Each form of stress can be equally debilitating to precision-based skills. A combination of any two stressors can magnify the deterioration of precision skills. Combinations of three or more stressors can trigger an immediate cascade of all precision skills. Further, survival stress trumps all combinations of stressors.

To combat these stressors during emergency situations, many medics employ “tactical breathing,” which, when done properly, turns off the SNS for short periods of time.

Multiple Precision Needs
The EMS professional’s operational requirement is precision, but not in one single area of performance. Rather, they require:

“Precision in Perception”— not a single sensory experience, but all of the processes simultaneously.

“Precision (Analytical) Processing” — the outcome of interpreting all of the perceptual sensory information into a single working hypothesis of patient symptoms and treatment.

“Precision-Based Pre­treatment”— an outcome of preparing your medical kit with products that are stress-compatible. A well-laid out and stocked kit reduces the time needed to treat a trauma patient. The kit should be also designed and stocked according to levels of trauma/care, in a way that compensates for stress-induced visual distortions. In addition, products within the kit must be designed to be gripped easily and firmly.

“Precision in Treatment”— the hallmark of an emergency medical professional. Virtually every skill an emergency medical professional provides requires hand-eye coordination within finite spaces.

“Precision in Demeanor”— the emergency medical professional must exude an aura of confidence, competence and calmness. All of these attributes are absorbed by the patient and directly affect the patient’s respiratory rates, blood pressure and the level of hemorrhaging.

Our Body’s Response
Extreme stress and absolute precision create a conflict within our body’s performance network, the autonomic nervous system (ANS). The ANS controls all of the voluntary and involuntary functions of the body, and is divided into the parasympathetic nervous system (PNS) and the sympathetic nervous system (SNS).

During waking hours and times of non-stress, the two branches work together to create a state of balance, or homeostasis, in which our high-level cerebral functions (perception, analysis, the execution of precision motor skills) are performed optimally. The SNS performs the opposite function of the PNS and is referred to as the “fight or flight response,” the “fear system,” the “predator defense system” and the “survival system.”

SNS activation stimulates the immediate release of stress hormones in proportion to the threat. It also increases arterial pressure and blood flow to large muscle mass (resulting in enhanced gross motor skill and strength), stimulates vasoconstriction of minor blood vessels at the end of the appendages, increases pupil dilation and causes cessation of the digestive process.

The SNS is always on a hair-trigger and is activated by perceiving conscious and unconscious threats. The result is a survival system that makes us explosively strong through increased adrenaline levels, whereby reactions to threats are automatic and without hesitation.

But our system gains speed by bypassing the high analytical capabilities of the prefrontal cortex. Thus, we become fast, quick and strong—but dumb—because we don’t need precision of perception, analysis and execution when running for the nearest tree.

Here lies the paradox: Our hard-wired survival system (SNS) is not conducive to the environmental stress of EMS.

Role & Outcome of SNS Activation
Our survival throughout history has been a byproduct of both our intellect and the hair-trigger wiring of the SNS. Our intellect works best when we have time, distance and cover, and are calm and in a quiet place where we can concentrate.

The SNS, on the other hand, is wired for spontaneous attacks, giving us an automatic and explosively quick system to survive charging predators or poisonous critters (stepping on a snake or touching a spider). SNS wiring is so sensitive it shaves one-half to two seconds from a consciously directed motor skill. Put into perspective: A grizzly bear can out-sprint a racehorse in a ¼-mile race. Thus, even a ½-second delay could be fatal when racing for a tree with a grizzly on your heels.

But reacting without accessing our intellect is just one of dozens of survival responses the SNS induces. Let’s take a closer look at how SNS activation affects other areas.

Perception: From the moment of arrival at an incident to the hand-off of a patient at the hospital, the emergency medical professional should be scanning the environment. Scanning perception must be continuous, adapting from wide to narrow and distant to near, and closer yet when applying medical care. When scanning, your head rotates, your pupils dilate and constrict, you orient your head to noise, and you recoil from putrid smells.

SNS activation, however, doesn’t allow for scanning, because it’s counter-productive to capturing as much information possible about a charging predator. During SNS activation, you’ll involuntarily lock all of your perceptual systems onto the pending threat through a process called perceptual narrowing, which provides the most information to the brain as possible. Perceptual narrowing will manifest itself as tunnel vision, auditory exclusion and the loss of touch sensations (as in not feeling pain).

Once the SNS is triggered, humans become binocular and lose the ability to focus on near objects. Depth perception is impacted, and detailed color vision is often lost, but in an interesting twist, our primal visual system locks onto certain colors—those that are associated with poisonous critters. Auditory perception is also likely to be impacted by the SNS.

Analytical Processing: Although the neural networks of analytical processing aren’t completely understood, the basic processes occur in the prefrontal cortex, which acts as the initiator, the time estimator and the self-monitor. It’s responsible for directing attention, focusing attention, ending focused attention, identifying the details of stimuli, etc.

More importantly, the prefrontal cortex is the center for precision perceptual processing, precision analytical skills and the formation (and execution) of precision motor skills (gross motor skills are formatted and launched from the older brain structures).

However, high-level prefrontal cortex processing can only occur during states of homeostasis. Functional magnetic resonance imaging (fMRI) scans have demonstrated that as stress increases, the efficiency of the prefrontal cortex breaks down and we become more instinctive or primal in action.

A breakdown of analytical processes results in a cascade of deteriorating performance. Perception, analysis, evaluation, precision motor skills, the processing of time that’s so critical in emergency care, memory of past experiences (successful and unsuccessful) are all lost.

Indecision, hesitation, failure to sense (hear, see, feel), failure to act, over-reaction or under-reaction should be expected when the SNS is triggered. Even the simple act of opening a bandage can be overwhelming. The prefrontal cortex is the center for precision, and without it the emergency medical professional functions at the same precision level as an ape.

SNS-InducedMotor Skills: Gross motor skills—those used when the SNS is activated, such as gripping, squeezing, pushing, pulling, sprinting or lunging—are enhanced by adrenaline. But when adrenaline isn’t used up in explosive movements, it continues to fire away within the muscles. The after-effect is not a fun experience; muscle tremors, uncontrolled shaking and the loss of most fine/complex motor skills occur.

SNS-induced motor skills are also affected by the brain’s survival circuit (thalamus-amygdala circuit). As explained previously, the prefrontal cortex is critical to higher functions, but is also the location for the formation and activation of fine and complex motor skills. The combination of the survival circuit and the effects of adrenaline lead to the loss of precision motor skills (either fine or complex skills).

For the emergency medical professional, there are several implications of SNS research. The most obvious: The EMS operational environment isn’t compatible with the operational requirement of pre­cision motor skills. Precision—from perception, to analytical processing, to motor skills—will be inhibited if not totally lost when the SNS is triggered, and this fact must be incorporated into training. EMS crews must be trained to control the SNS, and team members must be taught to scan for signs of SNS activation among crewmembers, so they can step in when necessary.

The next implication centers on the design and development of a medical kit. The SNS narrows visual perception, so personnel will overlook products if the kit isn’t laid out in a system conducive to trauma priorities. The loss of fine and complex motor skills must also be made a priority, as the SNS inhibits the ability to manipulate small, smooth objects that become slippery.

Finally, SNS research reveals the liability related to human error. This research has been used dozens of times to defend police officers, pilots and soldiers who were victim to their SNS. The bottom line: There will be times when a good operator makes a mistake, but the mistake is due to uncontrollable factors that triggered the SNS. The ramifications of this research not only impact the agency’s finances, but also the guilt an emergency medical professional may carry for life. On more than one occasion, I’ve given a lecture on extreme performance human factors and have been posed the following question from an audience member: “Then there’s nothing wrong with me?”

In each case the question came from someone who had been carrying unnecessary guilt that was as heavy as any cross you could carry. This research should be considered preventative medicine.

Bruce Siddle is a 20-year (plus) law enforcement veteran specializing in training and survival human factors. He is the founder of PPCT Management Systems and the managing partner of Warrior Science Group. Siddle has been a consultant for hundreds of criminal justice and public safety agencies, including the U. S. Department of State’s Diplomatic

Security Service, FBI’s Hostage Rescue Unit, U. S. Secret Service Counter Assault Team, the Transportation Security Agency, U.S. Armed Forces and the Queen of England’s personal protection unit. He is the author of Sharpening the Warrior’s Edge and is working on a second text, Warrior Science, The Study of Combat Human Factors. Siddle has reported receiving honoraria and/or research support, either directly or indirectly, from the sponsor of this supplement, North American Rescue.

The author would like to thank Sean McKay, Dave Grossman and Dr. Steve Stahle for their assistance in preparing this article.