In brief: Decide whether the patient can safely reach definitive care with the treatment, oxygen, monitoring, staffing, and time available onboard. Start escalation while options still exist.
Why the medevac call is uniquely hard
At sea, escalation can mean diverting a vessel, requesting a helicopter near the edge of its range, arranging a boat transfer, or accepting a multi-day sail to a capable port. Each option carries clinical, aviation, maritime, and operational risk.
The failure modes run both ways. An unnecessary evacuation can expose crews and patients to a hazardous transfer. A delayed request can leave a deteriorating patient onboard after weather, darkness, range, or vessel position removes the safest option.
The four forces to weigh
Patient trajectory: assess not only current observations but the expected condition in 6, 12, and 24 hours with realistic onboard treatment.
Onboard capability: define what the team can start and sustain. Oxygen, blood, drugs, monitoring, procedures, staffing, fatigue, and infection-control capacity all have limits.
Time to the right facility: the nearest port is not always the nearest capable hospital. Confirm transfer time, specialty capability, and acceptance.
The evacuation environment: weather, sea state, daylight, helicopter range, landing or winching constraints, and coastguard availability can rapidly change the choices.
The evacuation window
The evacuation window is the period in which transfer remains both clinically useful and operationally possible. It can close because the patient becomes too unstable to move, the ship sails beyond range, weather deteriorates, or a receiving facility becomes unavailable.
Using TMAS well
Contact TMAS early with the working diagnosis, current condition, trend, treatment and response, key uncertainties, capability gap, oxygen and staffing endurance, vessel position, route, weather, and the specific decision you need support with. Record the time, advice, and reassessment triggers.
A structured framework
- Define the syndrome and trajectory. What is happening and which findings suggest deterioration?
- Map the capability gap. What investigation, treatment, monitoring, staffing, or specialist input is unavailable?
- Calculate time and endurance. Compare time to a capable facility with oxygen, medication, battery, blood, and personnel endurance.
- Identify every transfer option. Helicopter, diversion, rendezvous, boat transfer, or continued passage carry different risks.
- Set triggers and a deadline. Define what change mandates action and when the preferred option stops being viable.
- Communicate a recommendation. Translate the clinical concern into a clear operational request.
Documenting a defensible decision
Record condition and trend, treatments and response, consultations, vessel position, time estimates, weather and sea state, resource limits, options considered, risks of transfer versus delay, the recommendation, who was informed, and the reassessment plan.
Practical checklist
- Assess trajectory, not only current stability.
- Name the exact capability gap.
- Confirm the nearest facility that can provide the required care.
- Calculate oxygen and staffing endurance against transfer time.
- Ask when weather, range, or daylight closes the preferred option.
- Use TMAS early and give the bridge a specific recommendation.
Related resources
Use the maritime medevac SBAR template, oxygen burn-rate calculator, and ECG interpretation guide.
Medical disclaimer: Educational and operational guidance only; not a replacement for clinical judgement, TMAS advice, employer procedures, rescue-service direction, or regulation.