I.  INTRODUCTION (content may vary)

    A.  Preview of skill and knowledge objectives, major topics in course
    B.  Preview of demonstrations and sham treatments
    C.  Attendance, grading, evaluation and examination policies
    D.  Review of gas laws, diving physics and physiology (optional)

II.  ROLE OF THE MEDIC

A.  RESPONSIBILITIES

1. Responsibilities as a diver

1. follow safe practice
2. set example
3. teach and instruct others

2. Responsibilities as a medic

1. emergency care, basic life support, stabilize
2. report accidents and treatment to medical authority
3. perform tasks and give aid as directed by proper authority
4. in absence of orders, carry out treatment and triage according to training and ability
5. encourage fitness in diving community
6. maintain proficiency in diving and emergency medicine
7. keep accurate, informative records – send with patient

B. LIAISON WITH OTHERS

1. knowledgeable physicians in medic’s own area- protocols, standing orders
2. local hospitals and chamber facilities
3. local EMS system
4. law enforcement, fire departments, Coast Guard, etc
5. communications system
6. Divers Alert Network (DAN)

III. RECORDS AND FITNESS (variable according to medic’s status, industry, and employer)

A. Baseline records

1. Knowledge of disqualifying conditions (permanent and temporary)
2. Review of diver’s medical history or previous physicals
3. Record family and emergency data
4. Routine exam (basic)

1. vital signs
2. ENT
3. heart and lungs

B.  Pre-dive evaluation

1. current or recent medical conditions
2. current drugs or medications
3. recent lifestyle or personal habits
4. recent dive history
5. brief physical exam (vital signs, ENT, heart and lungs)

C. Post-dive evaluation

1. dive and decompression history
2. brief physical
3. neuro and mental status evaluation

IV. DECOMPRESSION SICKNESS

A. Pathophysiology

1. Separation of inert gas bubbles from soluble phase to gas phase

1. intravascular bubbles
2. tissue/extravascular bubbles

2. Bubble effects

1. direct – possible obstructed blood flow, ischemia; possible effects on tissue, neural tissue, local chemical mediators
2. indirect – hematological reactions to bubble surface, platelet and enzyme effects, capillary permeability, hemoconcentration and edema, hypovolemia

3. Complications

1. cardiopulmonary – bubbles clogging pulmonary artery, right-to-left shunting of  bubbles, tachypnea, possible congestion of epidural veins, reduced cardiac output
2. neurological – possible cerebral and spinal emboli

B. Predisposing factors – concept of lowered resistance to bends

1. dehydration
2. poor fitness
3. illness and hangover
4. possible role of exercise during dive and decompression
5. age
6. cold
7. rapid gas switch

C. Signs and Symptoms

1. “Type I” – minor

1. pain only – joint pain (not spinal pain), normal neuro exam
2. skin – itching, mild rash

2. “Type II” – serious

1. sensory abnormalities, radicular pain
2. weakness, paralysis
3. vestibular symptoms – hearing, balance
4. mood, intellect, personality changes
5. visual symptoms
6. pronounced rash, “marble skin”

3. Vague, generalized symptoms

1. flu-like symptoms
2. marked fatigue
3. headache, disorganized, difficulty concentrating
4. DCS as “great imitator” – may mimic everyday illness
5. role of test of pressure – done where symptoms don’t seem to require treatment, neuro is normal, decision is not to treat
6. need for suspicion, treating doubtful case

D. Treatment

1. Treatment tables

1. USN tables – 5, 6, 6-A, 7, modified 4
2. others – Royal Navy 71 and 72, Comex 30 and 30-A, Lambertsen 7-A, USN and  other saturation tables
3. concept that treatment tables are specialized decompression, treatment table is dose of medicine (oxygen) different tables represent treatments for variable severity of DCS

2. Treatment flow chart

1. strongly suggested is chart in Field Guide for Diver – Medic with captions, notes and comments
2. other suitable, integrated flow chart

3. Fluids and drugs

1. importance of hydration – oral or IV fluids, good urine output
2. possible role of drugs, usual doses (Valium, Decadron, Dextran, etc)
3. emphasize basic treatment for bends is pressure, oxygen, fluids, and time; proper role of medications is debated; given by medic on direct or standing order

4. In-water oxygen treatment (optional) – as described in Diving and Subaquatic Medicine by Edmonds, Lowry, and Pennefather
5. Role of the monoplace hyperbaric chamber, limitations, etc (optional)

V. BAROTRAUMA

A. Squeeze

        1. Sinus – signs and symptoms, need approximately 3-10 days to heal; possible
            secondary sinus infection
        2. Middle ear – signs and symptoms; perforation of eardrum; possible secondary otitis media
        3. other squeeze – suit, “reverse” squeeze, etc

B. Lung overpressure

        1. review usual causes- rapid ascent, pressure reduction and wave surge, panic and breath
            holding; lung disease or abnormality

        2. pathology – rupture alveolus, expanding air ruptures through pleural surface, or tracks
            along tissue planes, or enters pulmonary circulation and left ventricle
           
        3. Mediastinal emphysema

1. air tracks along lung tissue planes and ruptures into Mediastinal space or pericardial sac
2. signs and symptoms – midchest pain or pressure, resonant or crunching heart sounds, cardiac tamponade (distended veins, narrow pulse pressure, low blood pressure and cardiac output), possible mild cyanosis, irregular pulse
3. treatment – varies from none (observation), to breathing oxygen, to recompression (seldom),  according to patient’s status and symptoms

         4. Subcutaneous emphysema

             a. burst upper lung leads to air tracking along upper bronchi, into tissue around neck and
                 clavicle
             b. signs and symptoms – pain or ache in neck or upper chest “sore throat”, pain with
                 swallowing, change in voice, palpable air under skin (“rice crispies”)
             c. treatment – same as 3.c (recompression seldom needed, minimal depth only)

         5. Pneumothorax

             a. expanding air ruptures through lung surface; free air present in chest cavity, outside
                lung
             b. small leak and/or occurring near surface will be simple pneumothorax
             c. if not near surface, any simple pneumothorax during decompression may become a
                 tension pneumothorax
             d. signs and symptoms of simple and tension pneumothorax same as from non-diving
                  causes (chest pain, splinting, dyspnea, shortness-of-breath, cyanosis, tracheal  
                  deviation, hypotension diminished breath sounds); improves with compression
             e. treatment of simple pneumothorax – varies from observation only to giving oxygen
                 (recompression seldom needed)
             f. treatment of tension pneumothorax:

                - compression deeper, or recompress to depth of significant relief
                - possible needle puncture to relieve pressure
                - after compression, use of saturated schedule and oxygen breathing to resorb trapped                       air (avoids chest wall puncture)
                - insertion of indwelling cannula or chest tube with seal or one-way valve
                - regardless of treatment, hold at depth of relief until stabilized before decompressing

            6. Cerebral air embolism

1. expanding alveolar air enters tributaries of pulmonary vein, transported to left heart, into aorta and cerebral arteries, causing stroke-like injury
2. signs and symptoms – usually rapid and dramatic; unconsciousness; convulsion; apnea;  paralysis and hemiparesis; hemiplegia; hemoptysis
3. possible occurrence of both air embolism and pneumothorax
4. treatment- standard USN 6-A (or similar) but deeper/longer tables may be necessary; use oxygen prior to reaching chamber, highest available concentration

VI. OXYGEN TOXICITY

A. Current, generally accepted concepts of oxygen toxicity (biochemical, neurotransmitters,
          physiologic)

B. Concepts of oxygen limits

          1. Lung vs. CNS
          2. Dry vs. in-water, working vs. at-rest

C. Lung toxicity

          1. Disruption of alveolar surfactant, small airway and alveolar closure, lung edema, disrupts
              gas transfer by lung
          2. Results are similar to pneumonia or respiratory distress syndrome
          3. Signs and symptoms
              a. varies from mild tracheal irritation, cough, painful breathing, dyspnea, cyanosis, death
              b. lungs sound relatively normal until advanced
          4. Treatment – lower pO2 unless end of treatment or decompression is near
          5. UPTD

1. concept – amount of damage from 100% oxygen at 1 ATA for one minute
2. typical UPTD dose causing 10%, 20%, loss of vital capacity, relationship to usual treatment tables
3. UPTD is only additive; role of air breaks in permitting high-done oxygen treatment

D. CNS toxicity

1. state of cerebral irritability
2. sign and symptoms – restlessness, irritability, twitching, tingling, visual symptoms, nausea, hiccups, convulsion; “VENTED”
3. treatment – remove mask/lower pO2, protect from harm during seizure, resume treatment after fifteen minutes