Hyperbaric Oxygen Therapy (HBOT) Nursing Guide

HBOT Fundamentals — Physics, Equipment & Treatment Parameters

Gas Laws Governing HBOT

Boyle's Law

At constant temperature, the volume of a gas is inversely proportional to its pressure: P₁V₁ = P₂V₂

Clinical Relevance

Gas-filled body spaces (sinuses, middle ear, intestinal gas, pneumothorax) compress on descent and expand on ascent. A 2 ATA dive halves gas volume; surfacing doubles it. This underpins barotrauma risk management.

Henry's Law

The amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid.

Clinical Relevance

At 3 ATA breathing 100% O₂, plasma O₂ rises dramatically. Nitrogen supersaturation on rapid ascent causes bubble formation → decompression sickness. Henry's Law also explains why HBOT floods plasma with dissolved O₂.

Oxygen Physiology at Pressure

0.3

mL/dL plasma O₂ at 1 ATA (air)

6.0

mL/dL plasma O₂ at 2 ATA (100% O₂)

10–15×

plasma O₂ increase at 2–3 ATA HBOT

6.0

mL/dL — enough to sustain tissue without Hb

2–3 ATA

typical therapeutic pressure range

100%

O₂ breathed via mask/hood

Chamber Types

Monoplace Chamber

Single patient; entire chamber pressurised with 100% O₂
Patient breathes ambient O₂ directly — no mask required
Limited nursing access during treatment
Lower cost; common in wound care outpatient settings
Fire risk: entire chamber is O₂-enriched — strict no-flammable policy
Monitoring via hull penetrators (ECG, SpO₂, BP)

Multiplace Chamber

Multiple patients (2–12+); chamber pressurised with air
Patients breathe 100% O₂ via tight-fitting mask or hood
Nurse/tender can enter and attend patients inside
Higher facility cost; used in military/dive medicine centres
Preferred for critically ill patients requiring monitoring
UAE/Saudi Navy facilities typically multiplace

Treatment Pressure Protocols

Indication	Pressure (ATA)	Duration	Sessions
Wound healing (diabetic foot, radiation)	2.0–2.5 ATA	90–120 min	20–40 sessions
Decompression illness (USN TT6)	2.8 ATA	~4.75 hours	1–several
CO poisoning	2.8–3.0 ATA	90 min	1–3 sessions
Arterial gas embolism (USN TT6A)	2.8–6.0 ATA	Variable	1–several
Necrotising fasciitis (adjunct)	2.4–2.5 ATA	90–120 min	10–30 sessions
Chronic refractory osteomyelitis	2.4–2.5 ATA	90–120 min	30–40 sessions

GCC Regional Context

HBOT Infrastructure in the GCC

Military & Naval Facilities

UAE/Saudi Arabia Navy dive medicine units operate multiplace chambers
Abu Dhabi Military Hospital — hyperbaric unit
Treats combat divers and recreational dive casualties

Expanding Wound Care Programmes

GCC has world's highest diabetes prevalence (20–25%)
Diabetic foot HBOT programmes growing in Dubai, Riyadh, Doha
King Faisal Specialist Hospital, Dubai Hospital, HMC Qatar lead programmes

UHMS-Approved Indications for HBOT

UHMS Standard

The Undersea and Hyperbaric Medical Society (UHMS) maintains the evidence-based list of approved indications. GCC regulatory bodies (DHA, DOH, SCFHS, QCHP) align with UHMS/international standards for hyperbaric nursing competencies.

Emergency / Acute Indications

EMERGENCY Decompression Sickness (DCS)

Type I (musculoskeletal, skin, lymphatic) and Type II (neurological, pulmonary, vestibular). Caused by nitrogen bubble formation on rapid ascent. Treat immediately with 100% O₂ and recompression.

▸USN Treatment Table 5 (Type I) or Table 6 (Type II)

▸Do not delay for diagnostic imaging

EMERGENCY Arterial Gas Embolism (AGE)

Air enters pulmonary veins on rapid ascent → coronary or cerebral arteries. Presents with immediate neurological deficit, stroke-like symptoms, or cardiac arrest post-dive.

▸Most serious dive emergency

▸USN Treatment Table 6A; position horizontal

URGENT Carbon Monoxide Poisoning

HBOT indications: COHb >25%, neurological symptoms, pregnancy (any COHb level), cardiac involvement, loss of consciousness.

▸HBOT reduces CO half-life: 5 hrs (air) → 90 min (100% O₂) → 23 min (3 ATA)

▸Prevents delayed neurological sequelae

URGENT Gas Gangrene / Clostridial Myonecrosis

Anaerobic infection (Clostridium perfringens). HBOT inhibits clostridial toxin production and has direct bacteriostatic effect on anaerobes. Adjunct to surgical debridement — does not replace surgery.

Wound & Tissue Healing Indications

Diabetic Foot Wounds

Wagner Grade 3–4 diabetic foot ulcers with failed conventional treatment. HBOT promotes angiogenesis, enhances leukocyte bactericidal activity, and improves wound oxygenation in ischaemic tissue.

▸TcPO₂ <40 mmHg at wound margin = candidate

▸Typical course: 30–40 sessions

▸High relevance in GCC (diabetes prevalence 20–25%)

Radiation Tissue Injury

Osteoradionecrosis (jaw), radiation cystitis, radiation proctitis, radiation-induced soft tissue radionecrosis. Radiation damages vasculature → hypoxic, hypovascular, hypocellular tissue. HBOT reverses this.

▸Pre-dental extraction in irradiated jaw: 20 pre-op sessions

▸Post-extraction: 10 post-op sessions (Marx protocol)

Chronic Refractory Osteomyelitis

Failed conventional antibiotic/surgical treatment. HBOT enhances oxygen-dependent neutrophil killing and improves antibiotic efficacy (aminoglycosides require O₂ gradient).

Compromised Skin Grafts & Flaps

Ischaemic/failing skin grafts and flaps. HBOT improves graft survival by reducing oedema, promoting angiogenesis, and maintaining peri-graft oxygenation.

Additional UHMS-Approved Indications

Necrotising Soft Tissue Infections

Adjunct to aggressive surgical debridement and antibiotics. Reduces mortality in necrotising fasciitis.

Crush Injury & Acute Traumatic Ischaemia

Reduces compartment pressure, prevents reperfusion injury, maintains tissue viability in acute crush.

Central Retinal Artery Occlusion

Emergency treatment within 24 hours. HBOT maintains retinal oxygenation via diffusion while clot resolves.

Air/Gas Embolism (Non-dive)

Iatrogenic (IV lines, surgery, procedures). Compress bubble volume, accelerate resorption.

Severe Anaemia (Exceptional)

When transfusion refused/unavailable. Plasma O₂ at 3 ATA sufficient to sustain life without haemoglobin.

Problem Wounds

Refractory pressure ulcers, venous stasis ulcers unresponsive to standard care with documented hypoxia.

Patient Assessment & Contraindications

Pre-HBOT Assessment Protocol

Pre-HBOT Safety Checklist — Fire Prevention & Contraindication Screen ▶

FIRE PREVENTION (O₂-enriched environment)

No petroleum-based products (petroleum jelly, oil-based creams, lip balm)
No alcohol-based products (hand sanitiser, perfume, hairspray, nail polish remover)
No flammable materials (newspapers, matches, lighters)
Cotton-only clothing (no synthetics, nylon, polyester — static electricity risk)
Remove all jewellery, hearing aids, wigs, prosthetics
No battery-powered devices without engineering approval
No contact lenses (monoplace — corneal damage risk from O₂ exposure)

Absolute Contraindications

Untreated pneumothorax — gas expands on ascent → tension pneumothorax
Concurrent bleomycin therapy (active)
Concurrent cisplatin therapy (active)
Concurrent doxorubicin (adriamycin) — active
Disulfiram (Antabuse) — blocks superoxide dismutase
Uncontrolled high fever (>38.5°C) — lowers seizure threshold

Relative Contraindications (assess individually)

COPD with CO₂ retention (hypoxic drive dependency)
Claustrophobia — assess; consider anxiolytic
Uncontrolled hypertension
Active seizure disorder
Upper respiratory tract infection (unable to equalise)
Patent foramen ovale — arterialisation of venous bubbles in DCS
Pacemakers — must be hyperbaric-rated; check manufacturer

Mandatory Pre-Treatment Investigations

Investigation	Purpose / What to Look For	Action if Abnormal
Chest X-ray	Rule out pneumothorax (absolute contraindication), bullae, air trapping	Insert chest drain before HBOT; defer until resolved
ENT / Audiological Assessment	Eustachian tube function — ability to perform Valsalva manoeuvre; tympanic membrane integrity	Myringotomy tubes if unable to equalise; defer active ear infection
ECG	Congenital heart defects, patent foramen ovale risk, arrhythmias	Cardiology referral; echocardiogram for PFO
Blood Glucose (BGL)	HBOT causes insulin sensitisation → hypoglycaemia risk, especially diabetics	Target BGL 7–15 mmol/L pre-treatment; avoid HBOT if <5 mmol/L
Medication Review	Bleomycin, cisplatin, doxorubicin, disulfiram	Absolute hold if active; discuss with prescribing physician
Claustrophobia Screen	Patient history, anxiety assessment (HADS score)	Anxiolytic medication pre-treatment; gradual exposure; consider multiplace chamber
Pacemaker Check	Verify device is hyperbaric-rated to treatment pressure	Contact manufacturer; obtain written clearance

Special Populations

Diabetic Patients

Check BGL before every session
HBOT increases insulin sensitivity — hypoglycaemia risk
Target range: 7–15 mmol/L (126–270 mg/dL) before entering chamber
Delay treatment if BGL <5 mmol/L — give glucose, recheck
Insulin pump: verify hyperbaric rating; often removed
Monitor BGL post-treatment; educate patient

Pregnant Patients

Pregnancy is a relative contraindication (not absolute)
Exception: CO poisoning in pregnancy — HBOT indicated even at low COHb due to foetal Hb affinity
Animal data: high O₂ tension may affect foetal development
Weigh risk of condition vs theoretical foetal risk
Obtain obstetric consultation before elective HBOT

Diving Medicine

Decompression Sickness (DCS)

Type I DCS — Mild

Musculoskeletal / Skin / Lymphatic

The Bends: joint pain (knees, shoulders, elbows) — dull aching, deep
Skin bends: marbling/mottling (cutis marmorata), pruritis
Lymphoedema: swelling, fatigue
Onset: 1–6 hours post-dive (most within 1 hour)
Treatment: USN Treatment Table 5 (2.8 ATA O₂, 135 min)

Type II DCS — Serious

Neurological / Pulmonary / Vestibular

Neurological: weakness, paralysis, sensory loss, bladder dysfunction
Pulmonary (Chokes): dyspnoea, chest pain, cough, cyanosis
Vestibular (Staggers): vertigo, nausea, hearing loss, tinnitus
Cerebral DCS: confusion, visual disturbance, unconsciousness
Treatment: USN Treatment Table 6 (2.8 ATA, 4.75 hours)

Arterial Gas Embolism (AGE)

Mechanism

Rapid ascent → lung over-pressure → alveolar rupture
Air enters pulmonary veins → left heart → systemic circulation
Bubbles lodge in coronary or cerebral arteries
Most serious diving emergency

Presentation & Treatment

Immediate onset (within 10 min of surfacing)
Stroke-like neurological deficit, cardiac arrest
Position: horizontal / supine (NOT head-down Trendelenburg)
Treatment: USN Treatment Table 6A (initial 6 ATA for severe cases)

USN Treatment Table 5 vs 6 vs 6A — Indication Guide ▶

Table	Indication	Pressure Profile	Duration	O₂ Periods
Table 5	Type I DCS (pain only, no neuro symptoms, resolved within 10 min at 2.8 ATA)	2.8 ATA descent → O₂ × 3 → 1.9 ATA → O₂ × 2 → surface	~2.25 hours	5 × 20 min O₂ with air breaks
Table 6	Type II DCS, Type I not resolved on Table 5, AGE (after initial stabilisation)	2.8 ATA descent → O₂ × 3 → 1.9 ATA → O₂ × 3 → surface	~4.75 hours	6 × 20 min O₂ with air breaks
Table 6A	Severe AGE, life-threatening DCS, unresponsive to Table 6	Initial descent to 6 ATA (air) → gradual reduction → 2.8 ATA (O₂) → surface as Table 6	Variable (~6+ hours)	O₂ at 2.8 ATA as Table 6

Key Nursing Point

Air breaks during O₂ breathing (5 min air every 20 min O₂) are mandatory to prevent CNS O₂ toxicity. The nurse/tender monitors the patient's breathing pattern and time on O₂ meticulously.

Field Management of Dive Casualties

Surface Oxygen Therapy

Administer 100% O₂ via non-rebreather mask at scene immediately
Reduces nitrogen bubble size by ~50% (reverses Henry's Law)
Reduces N₂ partial pressure in blood → drives N₂ out of bubbles
Continue until definitive recompression treatment
Do NOT re-dive the patient — worsens outcome
Horizontal positioning — prevents cerebral air migration

DAN Emergency Resources

DAN (Divers Alert Network): 24/7 emergency medical hotline
International: +1-919-684-9111
Assists with nearest recompression chamber location
Medical director consultation for complex cases
GCC: coordinates with UAE/Saudi/Qatar dive medicine units
Evacuation logistics support

Dive Profile & Risk Factors

High-Risk Dive Profiles

Exceeding no-decompression limits (NDL)
Rapid ascent (>9–18 m/min)
Repetitive dives without adequate surface interval
Deep dives (>40 metres — decompression required)
Diving at altitude (lakes — lower ambient pressure)
Flying after diving (<18–24 hours post-dive)
Dehydration — increases DCS risk
Patent foramen ovale — paradoxical embolism risk

GCC Diving Environment

Red Sea: popular liveaboard diving; strong currents; marine envenomation
Arabian Gulf: shallow (<100m), warm; jellyfish, stonefish, sea urchins
Large expatriate recreational diving community in UAE/Qatar
Tourist dive accidents common in Musandam (Oman), Sharm El-Sheikh (Egypt)
Nearest recompression chambers critical for rapid response
Nitrox diving (enriched air) — lower DCS risk but higher O₂ toxicity risk

Chamber Nursing Care

Pre-Treatment Preparation

Fire Safety & Prohibited Items

No petroleum jelly, oil-based creams, lip balm
No perfume, cologne, hairspray, deodorant (aerosol)
No nail polish or nail polish remover
No synthetic fabrics (nylon, polyester, acrylic)
No matches, lighters, cigarettes
No battery-powered devices without engineering sign-off
No contact lenses (monoplace) — oxygen absorption damage
Provide cotton gown/clothing for all patients

Patient Preparation Checklist

Remove all jewellery, watches, hair clips
Remove hearing aids, removable dental prosthetics
Ensure patient has voided (2 hour sessions)
Blood glucose check (diabetic patients — every session)
Assess ear equalisation ability (Valsalva demonstration)
Explain compression/decompression sensations (ear fullness, warmth)
Establish communication signal (e.g., hand signal for ear pain)
Connect monitoring leads (ECG/SpO₂/BP via hull penetrators)

O₂ Toxicity Recognition & In-Chamber Emergency Management ▶

CNS Oxygen Toxicity (Paul Bert Effect)

Occurs at pressures >1.6 ATA pO₂ — most concern during HBOT (>2 ATA on 100% O₂)

VENTID-C Mnemonic — Warning Signs

Visual disturbances (tunnel vision, flickering)
Ear symptoms (tinnitus, buzzing)
Nausea / vomiting
Twitching (lip twitching — earliest sign)
Irritability / anxiety / restlessness
Dizziness / vertigo
Convulsion (seizure — end stage)

In-Chamber Emergency Protocol (CNS O₂ Toxicity)

Remove O₂ mask immediately — patient breathes chamber air
Sit patient upright (monoplace: position supine with head elevated)
Inform attending physician immediately
If seizure: protect airway, do NOT deflate chamber rapidly
During seizure in chamber: seizure self-terminates when mask removed (air breathing)
Abort treatment — initiate controlled decompression
Document time, symptoms, interventions
Air breaks prevent recurrence — standard 5 min air per 20 min O₂

Pulmonary O₂ Toxicity (Lorrain Smith Effect)

Occurs with prolonged exposure at >0.5 ATA pO₂. In HBOT: substernal burning/cough/dyspnoea after multiple prolonged sessions. Reversible if O₂ exposure reduced. Air breaks are protective. Distinguished from CNS toxicity by gradual onset and absence of seizure.

Intra-Treatment Nursing Monitoring

Parameter	Method	Normal / Alert Values
SpO₂	Pulse oximeter via hull penetrator	Target >98%; if dropping — check mask seal, airway
ECG	Leads via hull penetrator (pressure-rated)	Monitor rhythm; bradycardia common at depth (vagal)
Blood Pressure	NIBP cuff via hull penetrator or manual	Mild hypertension expected; alert if >180/110 mmHg
Communication	Intercom / viewing port (multiplace: direct verbal)	Confirm ear comfort every 2–3 min on descent
Respiratory	Visual observation	Watch for CNS O₂ toxicity (lip twitch, facial grimace)
O₂ Time	Nurse timekeeper	Air break every 20 min; strict adherence mandatory

Complications Management

Middle Ear Barotrauma

Most common HBOT complication. Eustachian tube dysfunction prevents pressure equalisation on descent.

Teed Classification & Management

Grade 0–1: mild discomfort — slow descent; Valsalva; swallow
Grade 2–3: haemotympanum/rupture — stop descent; consult ENT
Preventive: decongestants, nasal spray pre-treatment
Refractory: myringotomy tubes (grommets) — referral to ENT

Sinus Barotrauma

Frontal/maxillary sinus most common
Facial pain, headache on descent or ascent
Exclude with imaging if recurrent
Management: decongestants, saline rinse, delayed treatment if URTI

Ocular Changes

Myopic shift: temporary near-sightedness (reversible within weeks)
Progressive with prolonged course (>20 sessions)
Advise patients against purchasing new glasses during treatment

GCC Context, Facilities & Exam Preparation

HBOT Facilities in the GCC

Facility	Country	Programme Focus	Chamber Type
King Faisal Specialist Hospital & Research Centre	Saudi Arabia (Riyadh)	Wound care, radiation injury, dive medicine	Multiplace + monoplace
Dubai Hospital (DHA)	UAE (Dubai)	Diabetic foot, wound healing, CO poisoning	Monoplace units
Hamad Medical Corporation (HMC)	Qatar (Doha)	Comprehensive HBOT; dive emergencies	Multiplace
Abu Dhabi Military Hospital	UAE (Abu Dhabi)	Military dive medicine; trauma; wound care	Multiplace
King Fahad Naval Base Hospital	Saudi Arabia	Naval dive medicine; DCS treatment	Multiplace

Regulatory Competency Frameworks

DHA / DOH (UAE)

Hyperbaric nursing competencies within critical care / wound care specialties
DHA exam: pharmacology, O₂ therapy, wound management — includes HBOT principles
DOH (Abu Dhabi): scope of practice includes hyperbaric nurse specialist
Focus on patient safety, O₂ toxicity management, emergency protocols

SCFHS (Saudi Arabia)

Hyperbaric medicine nursing content in specialty nursing examinations
Prometric-style MCQs covering DCS, CO poisoning, HBOT contraindications
Saudi dive medicine fellowships include HBOT nursing orientation
Emphasis on Boyle's/Henry's laws, treatment tables, patient monitoring

QCHP (Qatar)

Qatar Council for Healthcare Practitioners nursing exam
Emergency nursing content includes dive medicine and HBOT
HMC Qatar provides hands-on hyperbaric nursing training

MOH (Various GCC)

Prometric nursing exams include critical care/emergency topics
HBOT topics: indications, contraindications, complications
Know: absolute contraindications, O₂ toxicity signs, first aid for DCS

GCC Exam MCQs — DHA / MOH / SCFHS / QCHP Style

Q1. A nurse is preparing a patient for hyperbaric oxygen therapy. Which of the following is an ABSOLUTE contraindication to HBOT?

A. Claustrophobia

B. COPD with CO₂ retention

C. Untreated pneumothorax

D. Pregnancy (first trimester)

Rationale: Untreated pneumothorax is the only true absolute contraindication. During HBOT pressurisation and especially decompression (ascent), a trapped pneumothorax will expand (Boyle's Law) → tension pneumothorax → life-threatening. Claustrophobia and COPD are relative contraindications managed with anxiolytics/monitoring. Pregnancy is relative; HBOT is indicated in CO poisoning during pregnancy.

Q2. A recreational scuba diver surfaces from a 40-metre dive and within 30 minutes develops right knee joint pain, skin mottling on the abdomen, and fatigue. What is the most likely diagnosis and appropriate immediate treatment?

A. Type I decompression sickness — 100% O₂ via NRB mask, horizontal position, DAN hotline, recompression

B. Type II decompression sickness — emergency intubation and mechanical ventilation

C. Arterial gas embolism — aspirate gas from intravenous line

D. Pulmonary barotrauma — needle decompression of the chest

Rationale: Joint pain (bends), skin mottling (cutis marmorata), and fatigue represent musculoskeletal and skin manifestations = Type I DCS. Immediate management: 100% O₂ via non-rebreather mask (reduces bubble size), supine/horizontal position, IV fluids, DAN hotline, transport to nearest recompression chamber. USN Table 5 or 6 depending on response. Do NOT re-dive.

Q3. During a hyperbaric oxygen therapy session at 2.8 ATA, a patient reports lip twitching, nausea, and visual flickering. The nurse's PRIORITY action is:

A. Immediately decompress the chamber to 1 ATA

B. Administer IV diazepam stat

C. Remove the oxygen mask and have the patient breathe chamber air

D. Increase flow rate of oxygen through the mask

Rationale: These are classic VENTID-C warning signs of CNS oxygen toxicity. The FIRST action is to remove the O₂ mask — breathing air immediately reduces pO₂ and aborts progression to seizure. Rapid decompression is dangerous (gas expansion, DCS risk). IV diazepam is only if seizure persists. Increasing O₂ flow would worsen toxicity.

Q4. A 45-year-old patient with a COHb level of 18% is brought to the emergency department following a house fire. She is 28 weeks pregnant and conscious but confused. Regarding HBOT:

A. HBOT is contraindicated because COHb is below 25%

B. HBOT is contraindicated in the second trimester of pregnancy

C. HBOT is indicated — pregnancy with CO poisoning at any COHb level warrants HBOT

D. Wait until COHb falls below 10% before considering HBOT

Rationale: Pregnancy is a special indication for HBOT in CO poisoning at ANY COHb level. Foetal haemoglobin (HbF) has higher affinity for CO than adult Hb, and foetal carboxyhaemoglobin can be significantly higher than maternal levels. The risk of delayed neurological sequelae to the foetus is high. HBOT reduces CO half-life from ~90 min (normobaric O₂) to ~23 min at 3 ATA. Neurological confusion also independently indicates HBOT.

Q5. A nurse is teaching a patient about preparation for their first hyperbaric oxygen therapy session for a diabetic foot ulcer. Which instruction is MOST important regarding blood glucose management?

A. Increase morning insulin dose by 20% before each session

B. Avoid eating for 4 hours before each treatment

C. Check blood glucose before each session; target 7–15 mmol/L; delay if <5 mmol/L

D. Blood glucose monitoring is not necessary unless the patient is on insulin

Rationale: HBOT increases insulin sensitivity, making hypoglycaemia the primary diabetic concern during treatment. All diabetic patients (regardless of medication type) must have pre-treatment BGL checked. Target: 7–15 mmol/L. If BGL <5 mmol/L, treat hypoglycaemia first, then recheck before proceeding. Fasting is not recommended (increases hypoglycaemia risk). Insulin dose adjustment should be discussed with the endocrinologist, not pre-emptively increased.

Interactive Tool — Decompression Illness Risk Assessment & Emergency Guide