Vital Signs at Sea: The Body’s First Language
Vital Signs at Sea: The Body’s First Language
When a guest collapses at dinner, a crew member staggers on deck, or a sailor clutches his chest mid-race, you don’t have a CT scanner or blood labs. What you do have is far more immediate: vital signs.
For adults, vital signs are the foundation of medical assessment. They reveal whether someone is stable, compensating, or crashing — often hours before advanced diagnostics are possible【Royal College of Physicians, 2017】【Jarvis, 2023】.
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The Six Core Vital Signs (Adults)
1. Heart Rate (Pulse)
• Normal: 60–100 bpm at rest【Jarvis, 2023】.
• Tachycardia (>100): Shock, bleeding, dehydration, fever, pain, or sepsis【Marino, 2014】.
• Bradycardia (<60): Hypothermia, raised intracranial pressure, heart block, medications — or normal in athletes【Marino, 2014】.
• Pulse quality matters:
• Weak/thready = poor circulation.
• Bounding = fever, hyperthyroidism, anxiety, or aortic regurgitation (not just hypertension).
• Irregular = arrhythmia (e.g., atrial fibrillation).
2. Blood Pressure
• Normal: ~120/80 mmHg in most adults, but healthy young adults may sit around 100 systolic【Jarvis, 2023】.
• Low (<90 systolic): May indicate bleeding, dehydration, or sepsis【Auerbach, 2017】.
• High (>140/90 repeatedly): Hypertension; acutely, >180/120 with symptoms suggests emergency【Marino, 2014】.
• Trend is key: Falling pressure in a sick patient is a late, dangerous sign【Royal College of Physicians, 2017】.
3. Respiratory Rate
• Normal: 12–20 breaths/min【Jarvis, 2023】.
• High (>20): Often the earliest warning of deterioration — sepsis, shock, acidosis, lung disease【Cuthbertson, 2007】.
• Low (<12): Opioid overdose, brain injury, end-stage illness【Marino, 2014】.
4. Temperature
• Normal: 36.0–37.5°C【Jarvis, 2023】.
• High (>38°C): Infection, inflammation, heat illness.
• Very high (>40°C): Heatstroke with CNS dysfunction【WHO, 2018】.
• Low (<35°C): Hypothermia, shock, endocrine failure【Auerbach, 2017】.
5. Level of Consciousness (AVPU or GCS)
• Alert, Voice, Pain, Unresponsive.
• Any deterioration suggests hypoxia, hypoglycaemia, stroke, seizure, or head injury【Auerbach, 2017】.
6. Oxygen Saturation (SpO₂)
• Normal: 95–100% on room air【WHO, 2018】. Some healthy older adults may sit at 93–94%.
• <92%: Hypoxia from pneumonia, asthma, drowning, or heart failure【WHO, 2018】.
• BE AWARE- False reassurance: Carbon monoxide poisoning can show a “normal” SpO₂【Auerbach, 2017】.
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Reading the Combinations
The power of vital signs is in patterns【Churpek, 2017】.
• Sepsis: Fever + tachycardia + low BP + tachypnoea + altered consciousness.
• Hypovolaemic shock: Tachycardia + low BP + rapid shallow breathing + clammy skin.
• Hypothermia: Low temperature + bradycardia + slow breathing + confusion.
• Heatstroke: Very high temperature + tachycardia + rapid breathing + falling BP + confusion.
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Case Studies at Sea
Case 1 — Heart Attack (Myocardial Infarction)
A 55-year-old guest complains of crushing chest pain.
• Pulse: Often tachycardic (110–130), may be irregular; occasionally bradycardic in inferior MI【Marino, 2014】.
• BP: Can be high from pain/anxiety, or fall with cardiogenic shock【Marino, 2014】.
• Resp rate: Elevated (20–28) due to pain and anxiety【Tobin, 1998】.
• SpO₂: Often normal initially, but may drop if pulmonary oedema develops【WHO, 2018】.
• Consciousness: Usually alert unless cardiac arrest occurs.
Clue: Chest pain + abnormal pulse/BP, especially with falling SpO₂, is heart attack until proven otherwise.
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Case 2 — Panic Attack
A 28-year-old crew member feels chest tightness, palpitations, tingling in hands.
• Pulse: Rapid (110–140), but strong【Jarvis, 2023】.
• BP: Usually normal or slightly raised【Marino, 2014】.
• Resp rate: Very fast (30–40) with hyperventilation【Tobin, 1998】.
• SpO₂: Normal (98–100%)【WHO, 2018】.
• Consciousness: Fully alert but anxious; may develop carpopedal spasm from low CO₂.
Clue: Tachycardia + hyperventilation + normal SpO₂ and BP = panic, not hypoxia.
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Case 3 — Pulmonary Embolism
A 40-year-old stewardess becomes acutely short of breath after a long flight.
• Pulse: Tachycardic (110–140)【Marino, 2014】.
• BP: Often normal early, but can collapse in massive PE【Marino, 2014】.
• Resp rate: High (24–30)【Tobin, 1998】.
• SpO₂: Frequently low (<90%) despite rapid breathing【WHO, 2018】.
• Consciousness: May be anxious/confused; sudden collapse possible in massive PE.
• Other possible signs: Low-grade fever, hemoptysis.
Clue: Tachycardia + tachypnoea + low SpO₂ with clear lungs = suspect PE.
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The Power of Trends
One number is a snapshot. A sequence is a story.
• BP 100/60 may be normal — unless it fell from 130/80 an hour ago.
• HR 110 could be stress — but if it rises steadily while SpO₂ falls, it’s shock.
• Fever of 38°C may be mild — but with rising respiratory rate and dropping BP, think sepsis【Churpek, 2017】.
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Why Vital Signs Come First
Emergency physicians, medics, and expedition leaders all begin here because vital signs are:
• Universal — the same in London, Palma, or the South Pacific【WHO, 2018】.
• Immediate — no labs needed.
• Predictive — deterioration often shows in vitals hours before collapse【Royal College of Physicians, 2017】.
• Life-saving — guiding oxygen, fluids, CPR, or evacuation【Auerbach, 2017】.
At sea, they are your diagnostic compass. By getting these trends and reporting them back to your telemedicine service (such as MSOS) you become the hands, eyes and ears of the doctor. Without them, you are sailing blind.
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Vital signs are not just numbers. They are the body’s language.
Master them. Read combinations, not just snapshots. Know how to take them like a pro and deliver them to your on call Doc’s. Because they will be able to know the difference between panic and pulmonary embolism, heatstroke and sepsis.
Because at sea — where time is short and help is far away — your ability to measure, interpret, and act on vital signs may be the difference between life and death.
Remember there are no ambulances where we go!
