Environmental ⛰️

Question 1

You have agreed to be the expedition doctor for a trek to the Everest base camp. (altitude 5300m)

i. Outline the proposed pathophysiology of:

Acute Mountain Sickness (AMS)/High Altitude Cerebral Oedema (2 marks)

High Altitude Pulmonary Oedema (2 marks)

ii. List 2 risk factors for the development of High Altitude Pulmonary Oedema at any given altitude (2 marks)

iii. List 5 clinical features of AMS (5 marks

iv. For severe High Altitude Pulmonary Oedema, list 4 treatment options (4 marks)

Answer 1

FEx Net - NSW Fellowship Course – NSLHD SAQ December 2017

**i. Outline the proposed pathophysiology of: Acute Mountain Sickness (AMS)/High Altitude Cerebral Oedema (2 marks) **

 Vasogenic cerebral oedema. Hypoxia appears to cause cerebral vasodilatation, leading to increased cerebral blood volume and blood flow.  Leaky BBB – due to loss of autoregulation and increased permeability.

**High Altitude Pulmonary Oedema (2 marks) **

 Non cardiogenic, hydrostatic oedema.  Widespread but uneven pulmonary vasoconstriction. Heterogeneity of the response causes diversion of flow to the less constricted areas with subsequent capillary leakage.

**ii. List 2 risk factors for the development of High Altitude Pulmonary Oedema at any given altitude (2 marks) **

 Rapid ascent
 Genetic predisposition
 Any pre-existing pulmonary hypertension (e.g. previous VTE/PE, cardiac shunts – e.g. ASD)
 Exertion
 Cold
 Use of sleeping medication
 Excessive salt ingestion

iii. List 5 clinical features of AMS (5 marks)

 Headache – worse with bending over or valsalva
 Anorexia, nausea, sometimes vomiting
 Lassitude, weakness, irritability
 Retinal haemorrhages
 Fluid retention - peripheral/facial oedema

iv. For severe High Altitude Pulmonary Oedema, list 4 treatment options (4 marks)

 Immediate descent
 Oxygen
 Minimise exertion
 Nifedipine
 Portable hyperbaric compression chamber
 CPAP/EPAP mask

Question 2

A 27 year old man climbed over an electricity sub-station fence and sustained an electrical injury while grabbing a metal pole with his right hand. He arrives 30 minutes later complaining of tingling in his right arm and a numb left foot.

A CLINICAL PHOTOGRAPH IS SHOWN

i. Describe the wound seen on the foot (1 mark)

ii. Complete the table outlining factors that determine the severity of an electrical injury (8 marks)

Category, Explanation
- Voltage
- Current
- Resistance
- Type of current

iii. For each of the three categories below, what specific injuries or problems may occur in the patient described in the stem? For each, describe the patho-physiological process (6 marks)

Cardiac
Nervous system
Limb soft tissue

Answer 2

FEx Net - Northern Sydney Hospitals Network 2 – SAQ paper 2016.1

i. Describe the wound seen on the foot (1 mark)

 Deep, full thickness burn to plantar aspect forefoot
 Depressed central area with surrounding eschar
 Sensible answer

ii. Complete the table outlining factors that determine the severity of an electrical injury (8 marks)

ATTACHED

iii. For each of the three categories below, what specific injuries or problems may occur in the patient described in the stem? For each, describe the patho-physiological process (6 marks)

Cardiac
- Variety of dysrhythmias
- High voltage injury likely (substation) Evidence of trans thoracic current

Nervous system
- Peripheral nerve injury/parasthesia/paralysis
- Current down arm and leg

Limb soft tissue
- Cutaneous burns
Vascular injury
- Current from hand-foot
Vasospasm/thrombosis/ischaemia
Heating of tissue

Question 3

A 30 year old male is brought by ambulance to your urban district ED from a local beach following a SCUBA dive. His dive buddy reports that the patient appeared to be behaving abnormally and possibly had brief seizure-‐type movements during their dive at a depth of 35 metres.

i. List3diving-‐relatedcausesofconfusionorbehaviourchangeatdepth(3marks)

Because of the problem at 35 metres, the buddy forced a rapid ascent and omitted a decompression stop at 10 metres. On the dive boat, the patient began to vomit and was very unsteady on his feet.

ii. List3differentialdiagnosesforthispresentationandoutlinehistoricalor examination features that would support each differential (9 marks)

iii. Completethefollowingtableofchangesinbubblesizewithchange(altitudeor depth) from sea level (4 marks)

iv. List3relativecontraindicationstohelicopterretrievalinthispatient(3marks)

Answer 3

FEx Net

i. List3diving-‐relatedcausesofconfusionorbehaviourchangeatdepth(3marks)

• Hypoxia – example from aspiration, breath-holding, gas supply failure
• Nitrogen narcosis
• Contaminated gas mix – example tanks filled near petrol-powered compressor with entrainment of CO
• Oxygen toxicity – if diving on high concentration O2

ii. List3differentialdiagnosesforthispresentationandoutlinehistoricalor examination features that would support each differential (9 marks)

ATTACHED

iii. Completethefollowingtableofchangesinbubblesizewithchange(altitudeor depth) from sea level (4 marks)

ATTACHED

iv. List3relativecontraindicationstohelicopterretrievalinthispatient(3marks)

• DCI/AGE – diving-related “bubble problems” because of Boyle’s Law
• Intra-cranial/intra-spinal air
• Other air if not decompressed (e.g. pneumothorax, bowel obstruction)
• Cardiac arrest requiring compressions (LUCAS et al may change this??)
• Aggressive, combative patient (risk to aircraft & crew unless adequately sedated/restrained)