Clinical Tool
Oxygen Planning
at Sea
Calculate oxygen endurance against evacuation time. Know when your supply runs out before the helicopter arrives. A core skill for maritime clinicians.
Why It Matters
Oxygen Is a Clock at Sea
Unlike a hospital, a ship carries finite oxygen. When a patient deteriorates, oxygen consumption rises. When evacuation is delayed by weather, sea state, or helicopter range, the gap between oxygen endurance and evacuation time becomes a critical clinical variable.
Maritime clinicians must think in terms of resource endurance versus clinical trajectory. If the oxygen runs out before the patient reaches definitive care, the clinical plan must change.
D-Type Cylinder
Common shipboard size
Typical Flow Rate
Non-rebreather mask
Endurance
At this rate, one cylinder
Typical Evacuation
Helicopter + transfer time
Framework
The Oxygen Planning Framework
Effective oxygen planning at sea involves five questions:
- How much oxygen remains? Count cylinders, check fill levels, calculate total litres available.
- What is the current burn rate? Flow rate in L/min multiplied by the number of patients on oxygen.
- How long until evacuation? Time to helicopter arrival, transfer time, and weather contingencies.
- Will the supply outlast the trajectory? Compare oxygen endurance against evacuation timeline.
- What if it will not? Flow rate adjustment, supplemental strategies, or escalation of evacuation urgency.
D-Type Cylinder, 10 L/min, Helicopter 4 Hours Away
Oxygen endurance: 340L ÷ 10 L/min = 34 minutes per cylinder.
Time to evacuation: 4 hours (240 minutes).
Cylinders needed: 240 ÷ 34 = 7.1 cylinders at this flow rate.
Decision: If fewer than 8 cylinders are available, reduce flow rate, consider supplemental strategies, or escalate evacuation urgency via SBAR-M bridge communication.
Medevac Context
Medevac Oxygen Planning
When recommending medical evacuation, the oxygen question is critical. The bridge and helicopter crew need to know:
- Current oxygen supply status and estimated endurance
- Whether the patient can maintain SpO2 at reduced flow rates
- The clinical trajectory if oxygen runs out before transfer
- Whether portable oxygen is available for helicopter transfer
- The impact of altitude on oxygen requirements during aeromedical evacuation
This information should be communicated using the SBAR-M framework, where the M (Maritime context) specifically includes resource endurance data and its operational implications.
FAQ
Oxygen Planning Questions
How do I calculate oxygen endurance?
Divide the remaining cylinder volume (litres) by the flow rate (litres per minute). Example: 340L cylinder at 10 L/min = 34 minutes. Multiply by the number of available cylinders for total endurance.
What cylinder sizes are typically found on ships?
Common shipboard sizes include D-type (340L), E-type (680L), and larger F/G cylinders. The exact inventory varies by vessel class, flag state requirements, and company medical policy. Always audit your supply during embarkation.
How does altitude affect oxygen during helicopter transfer?
Helicopter cabin altitude (even in pressurised aircraft) may increase oxygen requirements. Flow rates that maintain SpO2 at sea level may be insufficient during aeromedical transfer. Communicate this to the helicopter medical crew during handover.
Is there a free oxygen calculator?
Yes. The Oxygen Burn-Rate Calculator is a free tool that calculates endurance against flow rate, cylinder size, and evacuation time.
Educational and operational support only. Does not replace employer protocols, telemedical advice, company medical policy, flag-state requirements, local regulations, or clinical judgment. Do not enter patient-identifiable information into clinical tools.
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The Red-Zone Card includes oxygen clock prompts, SBAR-M bridge updates, and medevac trigger criteria in a quick-reference format.
Digital resources. Instant access. 30-day refund policy. Educational support only.