10.3 Crew Resource Management (CRM) and Human Factors

Crew Resource Management (CRM) and Human Factors

The critical care transport environment is dynamic, high-stakes, and inherently hazardous. Crew Resource Management (CRM) is a system of principles, tools, and behaviors designed to optimize team performance, improve communication, and mitigate the impact of human error. Initially developed by NASA and commercial aviation in the late 1970s, CRM has been widely adopted in medicine, particularly in critical care transport, where crew member coordination directly impacts survival.

Core CRM Principles

CRM focuses on maximizing situational awareness, flattening steep hierarchies, standardizing communication, and structuring decision-making.

The Sterile Cockpit Rule

Derived from Federal Aviation Regulation (FAR) Part 121.542, the Sterile Cockpit Rule prohibits crew members from performing non-essential duties or engaging in non-operational conversation during critical phases of flight.

• In aviation, critical phases include taxi, takeoff, landing, and all flight operations below 10,000 feet (except cruise flight).
• In HEMS operations, a sterile cockpit is maintained during takeoff, landing, low-altitude transit, operations in high-traffic areas, or whenever the pilot requests it.
• During these times, the medical crew must restrict communication to flight-related safety issues, such as traffic spotting, obstacle avoidance (e.g., "wires front-left"), and cockpit warnings. Clinical discussions or casual conversations are strictly prohibited to ensure the pilot's undivided attention is focused on flying.

Situational Awareness (SA)

Situational awareness is the continuous perception of the elements in the environment, the comprehension of their meaning, and the projection of their status in the near future. In transport, this includes monitoring aircraft systems, weather conditions, fuel status, patient physiological trends, and crew fatigue.

Losing situational awareness is a primary contributor to Controlled Flight into Terrain (CFIT) and clinical errors. Warning signs of lost situational awareness include:

• Fixation: Focusing on a single task (e.g., struggling with an IV line) to the exclusion of the overall environment.
• Ambiguity: Having conflicting information without seeking clarification.
• Confusion: Not understanding a system state or clinical trend.
• Deviation: Straying from standard operating procedures (SOPs) or flight plans.

Structured Decision-Making: The DECIDE Model

Aeronautical Decision Making (ADM) relies on structured cognitive models to process information under stress. The DECIDE model is a six-step loop:

1. Detect: Identify that a change has occurred (e.g., patient's EtCO2 drops to 15 mmHg).
2. Estimate: Determine the significance of the change and the need to react (e.g., hyperventilation, circuit disconnect, or accidental extubation).
3. Choose: Select a desirable outcome for the flight or patient (e.g., restore normal ventilation).
4. Identify: Formulate actions to achieve the outcome (e.g., check tube placement, check connections, auscultate breath sounds).
5. Do: Implement the necessary actions (e.g., reconnect circuit or re-intubate).
6. Evaluate: Assess the effectiveness of the actions (e.g., EtCO2 returns to 40 mmHg, chest rises).

Communication and Assertion Tools

To overcome the "authority gradient"—the natural reluctance of junior crew members to speak up or challenge a pilot or senior clinician—CRM provides structured assertion tools:

• Closed-Loop Communication: A three-way communication technique where the sender states a message, the receiver repeats it back to confirm accuracy, and the sender confirms the feedback. For example:
  • Sender (Paramedic): "Set the ventilator to a tidal volume of 450 milliliters."
  • Receiver (Nurse): "Setting tidal volume to 450 milliliters."
  • Sender (Paramedic): "That is correct."
• The CUS Tool: A graded escalation tool used to express concern without causing defensiveness:
  • Concerned: "I am concerned about our fuel reserve."
  • Uncomfortable: "I am uncomfortable with this weather ceiling."
  • Safety Issue: "This is a safety issue. We need to turn back."
• The Five-Step Advocacy/Assertion Loop:
  1. Get Attention: Use the person's name ("John...").
  2. State Concern: Express the observation ("I see power lines ahead of us").
  3. State Problem: Explain the hazard ("We are flying too low to clear them").
  4. Offer Solution: Suggest an action ("We should climb immediately").
  5. Obtain Agreement: Ask for confirmation ("Do you agree?").
• Two-Challenge Rule: If a crew member observes an unsafe condition, they must challenge the decision-maker at least twice. If the second challenge is ignored, the member is empowered to take direct action to ensure safety (e.g., taking control of the radios or initiating emergency procedures).

Human Factors and Fatigue Management

Human factors refer to the physiological, psychological, and social characteristics that affect human performance. Fatigue is one of the most critical threats in HEMS operations.

Physiology of Fatigue

Fatigue impairs cognitive function, slows reflexes, narrows visual field, and degrades decision-making. Working a 24-hour shift without rest is cognitively equivalent to having a blood alcohol concentration (BAC) of 0.10%, which exceeds the legal limit for driving.

• Circadian Rhythm: The body's internal 24-hour clock. The lowest point of alertness (circadian trough) occurs between 02:00 and 06:00, a period associated with a higher rate of transport accidents.
• Sleep Inertia: A temporary state of cognitive impairment, grogginess, and disorientation experienced immediately after waking. It typically lasts 10 to 30 minutes. Crews waking up for a sudden flight request must be allowed time to clear sleep inertia before executing critical tasks.

CAMTS Fatigue Mitigation Standards

CAMTS outlines specific policies to manage crew fatigue:

• Shift Length: Crew duty time is typically limited to a maximum of 24 hours.
• Mandatory Rest: During a 24-hour shift, crew members must have a minimum of 8 hours of uninterrupted rest capability. If the base experiences high call volume and the crew does not get adequate rest, the crew must declare themselves fatigued and "opt out" of service.
• Duty and Rest Cycles: A crew member must not exceed a maximum number of consecutive hours of flight time or duty time without a mandatory day off.
• Environmental Factors: Programs must provide appropriate crew quarters that are quiet, dark, and temperature-controlled to facilitate restorative sleep.

Safety Culture

A healthy safety culture is built on a Just Culture. A Just Culture distinguishes between:

• Human Error: Inadvertent slips or lapses (e.g., misreading a label). Managed by console and process redesign.
• At-Risk Behavior: Intentional shortcuts where the risk is believed to be insignificant or justified (e.g., failing to use a checklist). Managed by coaching and reinforcing safety norms.
• Reckless Behavior: Conscious disregard of a substantial and unjustifiable risk (e.g., flying in known sub-minimum weather). Managed by disciplinary action.

A Just Culture encourages the reporting of errors and near-misses (non-punitive reporting) so the system can learn and improve, rather than punishing individuals for system failures.