Environmental Emergencies
Question 142 of 180
A 43 year old woman is brought to the Emergency Department after drowning at a nearby beach. She was seen to be struggling before she became submerged below the waterline. She was in cardiac arrest when removed from the water and advanced life support is ongoing. Which of the following factors has been associated with a poor prognosis after drowning?
Answer:
The follow factors at presentation have been associated with a poor prognosis:- Duration of submersion >5 minutes (most critical factor)
- Time to effective basic life support >10 minutes
- Resuscitation duration >25 minutes
- Age >14 years
- Glasgow coma scale <5 (i.e. comatose)
- Persistent apnea and requirement of cardiopulmonary resuscitation in the emergency department
- Arterial blood pH <7.1 upon presentation
Drowning
Environmental Emergencies
Last Updated: 4th August 2021
Definitions
- Drowning is defined as a process resulting in primary respiratory impairment from submersion or immersion in a liquid medium. Implicit in this definition is that a liquid/air interface is present at the entrance of the victim's airway preventing the victim from breathing air.
- Submersion occurs when the face is underwater or covered in water. Asphyxia and cardiac arrest occurs within a matter of minutes of submersion.
- Immersion, by contrast, is when the head remains above water, in most cases by means of a life jacket. In most situations of immersion, the victim remains immersed with an open airway and becomes hypothermic, although aspiration of water may occur if water splashes in the face or if the victim becomes unconscious with their face in the water.
Pathophysiology of drowning
- Following submersion, the victim initially breath holds by reflex, and frequently swallows water.
- As breath holding continues, hypoxia and hypercapnia develop.
- A reflex laryngospasm may temporarily prevent the entrance of water into the lungs.
- Eventually these reflexes abate and the victim aspirates water.
- Bradycardia, as a consequence of hypoxia, occurs before sustaining a cardiac arrest.
- Correction of hypoxaemia by ventilation-only resuscitation is critical and in itself may lead to ROSC in some cases.
Water rescue
- Whenever possible, bystanders should attempt to save the drowning victim without entry into the water; talking to the victim, reaching with a rescue aid, or throwing a rescue aid may be effective if the victim is close to dry land
- Rescue can present significant risk to the rescuer but a sensible risk assessment is necessary to ensure that potentially survivable victims are rescued promptly
- If entry into water is essential, take a buoyant rescue aid, floatation device or boat; it is safer to enter the water with two rescuers than alone
- Trained rescuers are often professionals with specialist equipment to assist with search and rescue and will base rescue attempts on the likelihood of survival; submersion durations of < 10 mins are associated with a very high chance of a good outcome and submersion durations of > 25 mins are associated with a low chance of a good outcome
- In the UK combined emergency services guidance recommends review of search and rescue efforts at 30 and 60 minutes for submersion (90 minutes may be appropriate for children or those submerged in icy cold water)
- Trained individuals should consider in-water ventilation (with the support of a buoyant rescue aid) only if there is likely to be delay in reaching land or a rescue craft
- Remove the victim from the water promptly; spinal precautions are unnecessary unless there is a history of diving in shallow water, or signs of severe injury after water-slide use, water-skiing, kite-surfing, or watercraft racing - remove them from the water as quickly as possible while attempting to limit neck flexion and extension
- Hypovolaemia after prolonged immersion can cause cardiovascular collapse/arrest on removal from water especially if the victim is upright; keep the victim in a horizontal position during and after retrieval from the water
Initial resuscitation once retrieved from water
- Check for response by opening the airway and check for signs of life; do not confuse agonal breathing with normal breathing
- Give 5 initial rescue breaths supplemented with oxygen if available
- If the victim has not responded to intial ventilations, place them on a firm surface before starting chest compressions; provide CPR in a ratio of 30 compressions to 2 ventilations
- Massive amounts of foam caused by mixing moving air with water and surfactant can sometimes come out of the mouth of victims; if this occurs, continue rescue breaths/ventilation until tracheal intubation can be attempted
- Regurgitation of stomach contents and swallowed water is common; if this prevents ventilation, turn the victim on their side and remove the regurgitated material using directed suction if possible
Modifications to ALS after drowning
- Airway and breathing
- Give high flow (10 - 15 L/min) oxygen, ideally through a oxygen mask with a reservoir bag to the spontaneously breathing patient
- Consider early tracheal intubation and controlled ventilation for victims who fail to respond to initial basic airway measures, who have a reduced level of consciousness or are in cardiac arrest (reduced pulmonary compliance requiring high inflation pressures may limit the use of a supraglottic airway device)
- In a patient who has not arrested or who has achieved ROSC, titrate the inspired oxygen concentration to achieve SpO2 of 94 – 98%; confirm adequate oxygenation and ventilation with arterial blood gases once available; set PEEP to at least 5 – 10 cm H2O (PEEP values of 15 - 20 cm H2O may be required if the patient is severely hypoxaemic; decompress the stomach with a gastric tube
- Circulation and defibrillation
- Palpation of a pulse as a sole indicator of cardiac arrest is not always reliable, particularly in the wet and cold drowning patient; as soon as possible check the ECG and end-tidal CO2 to confirm presence or not of a cardiac output
- If the victim is in cardiac arrest, follow standard ALS protocols; if the patient is hypothermic, modify the approach for treatment of hypothermia
- Assess the rhythm and attempt defibrillation if indicated according to standard protocols; dry the victim's chest before applying defibrillator pads
- After prolonged immersion, most victims will have become hypovolaemic due to the cessation of the hydrostatic pressure of water on the body; give rapid IV fluid to correct hypovolaemia commenced out of hospital if transfer time is prolonged
- Discontinuing resuscitation efforts
- Making a decision to discontinue resuscitation efforts on a victim of drowning is difficult; no single factor predicts good or poor survival
- Continue resuscitation unless there is clear evidence that such attempts are futile (e.g. massive traumatic injuries, rigor mortis), or timely evacuation to a medical facility is not possible
- Neurologically intact survival has been reported in several victims submerged for longer than 25 min, however these case reports almost invariably occur in children submerged in ice-cold water
- Post-resuscitation care
- Follow standard post-resuscitation guidelines
- Many victims of drowning are at risk of developing acute respiratory distress syndrome (ARDS) and standard protective ventilation strategies for ARDS should be followed
- Extracorporeal membrane oxygenation (ECMO) has been used for those in refractory cardiac arrest, those with refractory hypoxaemia and in selected cases of submersion in ice cold water
- Pneumonia is common after drowning; consider prophylactic antibiotics after submersion in grossly contaminated water such as sewage
- Neurological outcome is primarily determined by the duration of hypoxia
End organ effects of drowning
- Pulmonary
- Noncardiogenic pulmonary oedema
- Acute Respiratory Distress Syndrome (ARDS)
- Pneumonia
- Neurological
- Cerebral hypoxaemia and ischaemia
- Cerebral oedema and raised intracranial pressure
- Permanent neurological damage
- Cardiovascular
- Arrhythmias secondary to hypothermia and hypoxaemia
- Other
- Metabolic and/or respiratory acidosis
- Renal failure
- Haemolysis and coagulopathy
Prognostic factors
The follow factors at presentation have been associated with a poor prognosis:
- Duration of submersion >5 minutes (most critical factor)
- Time to effective basic life support >10 minutes
- Resuscitation duration >25 minutes
- Age >14 years
- Glasgow coma scale <5 (i.e. comatose)
- Persistent apnea and requirement of cardiopulmonary resuscitation in the emergency department
- Arterial blood pH <7.1 upon presentation
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
