Drowning is defined as ‘death by immersion in a liquid. A person who is resuscitated even if only for more than 24 hours has classically been defined by some as a near-drowning but the AHI is pulling away from this difference.

A person who has been successfully resuscitated may still die from complications associated with the drowning event. These complications will be discussed in detail.

While the drowning person will try to hold his breath for as long as possible, for most people, a PaC0₂ of 55 torr or more will demand a ventilatory effort even if it only brings in water. Some swimmers have been trained past this point.

Persons at highest risk for drowning are small children under 4 years of age who drown in bath tubs and swimming pools and then there is another peak in drowning deaths in teenagers in lakes & rivers. Males are more likely to die of drowning than females at any age. 

Drowning deaths in very small children and infants suggest that neglect or abuse must be investigated. 

While substance abuse is a commonly reported risk factor, seizures, strokes (CVA)  MI, hypothermia, inability to swim, fatigue, homicide, and suicide are all linked to drowning and near-drowning episodes. 

Hyperventilation prior to diving can cause ‘shallow water blackout.’ The person hyperventilates to blow off the C0₂.  When he dives, the partial pressures of the gases rise under the hyperbaric conditions underwater, so his ventilatory drive is not triggered by hypoxemia. As he surfaces, once the Pa0₂ drops below 25-30 mmHg, the patient losses consciousness.   

Discuss the effect of water temperature on survival 

Persons who drown in icy water (less than 5⁰ C) and whose core temperature dropped to around 30⁰ C  may have such suppression of VS that they might be pronounced dead, but it is important to do CPR and get the temperature up before deciding they are really dead.  

Because of the decreased metabolism associated with hypothermia, patients have been successfully resuscitated after a long period under water.  

It is important to remember that survival from drowning depends not only on the temperature of the water, but the size of the patient. A child in icy water cools off more quickly than an adult will, so the protection afforded by hypothermia is size dependent as well as temperature-dependent.

Pathophysiology:  

“35% of childhood drownings end in death, 33% result in some degree of neurological impairment and 11% in severe brain damage.” Kids fare better than adults! 

1.    anoxia and mixed acidosis cause cardiac arrest and significant central nervous system damage

2.    massive influx of water into the airways triggers laryngospasm in about 15% of the population, while the rest will aspirate a significant amount of water into the lungs [4 ml/kg.]

3.    masses of fresh and saltwater into the alveoli washouts  the pulmonary surfactant causing decreased lung compliance

4.    it is possible that pulmonary edema may be triggered by extremely high negative pressures created by the person trying to breathe through a closed glottis

5.    others feel that the pulmonary edema can be due to the increased permeability of the pulmonary capillaries due to the hypoxic insult.

6.    in some, particularly small children, immersion in water can trigger the diving reflex in which  there is apnea, bradycardia and vasoconstriction of nonessential capillary beds

7.    bronchospasm can be triggered by the water hitting the central airways

8.    in saltwater drowning, protein-rich fluid fills the alveoli & interstitial spaces so that diffusion of 0₂ is decreased.

9.    It was long felt that salt water drowning can cause problems with osmotic & hydrostatic pressure inside the lung and even effect blood volume, but the AHI is suggesting now that this has not been seen clinically as much as was expected.

10.  if the water aspirated was contaminated, serious pulmonary infections can cause bronchopneumonia and even abscess formation.

11.   anoxic encephopathy can result from diffuse cerebral edema associated with lactic acid.   

 

Treatment of the drowning patient

1.    Prompt, effective CPR is the most important treatments of drowning. Start mouth-to-mouth while the patient is still in the water.

2.    If you don’t feel a pulse in a hypothermic patient, continue to do CPR because the pulses are difficult to palpate in the hypothermic patient  

REMEMBER! 90% of patients who arrive at the ER with a pulse will survive with intact brain function.

3.    According to the AHI, unless there was a history of diving or falling into the water, we no longer need to assume there is a spinal cord injury.

4.    Do not attempt to remove water from the lungs by Heimlich or CPT, the fluid will be absorbed by the lymphatics & is just a waste of time.

5.    If the patient is breathing and able to protect his airway, start with 100% NRB and get an ABG to wean them. We must observe this patient for 4-6 hours because pulmonary edema can develop later.

6.     if 100% is not enough, as long as he can protect his airway & is not at risk for vomiting and he can keep his PaC02 WNL, we can place him on nasal CPAP with heated, humidified 0₂.

7.    if the patient cannot protect his airway, he needs intubation

8.    Patients who vomit need their airway cleared out immediately before continuing to bag. We may need to give antibiotics if vomitus was aspirated.

9.    if the patient cannot breath effectively, he needs mechanical ventilation

10. if a history of falling or diving, the spinal column  must be protected until spinal injury has been r/o by cross-table lateral x-ray of the spine

a.     establish airway with jaw-thrust

b.     place cervical collar

c.     put patient on backboard 

d.     midline the head with sand bags

11.  The patient must be warmed if he is hypothermic—but don’t delay CPR for warming.

a.     Persons with severe hypothermia (less than 30⁰ C) may require active internal procedures such as warmed IV, heated blankets even ECMO 

12. remember that divers who have suffered drowning may be suffering the ‘bends’ and need a Hyperbaric chamber to reduce the N2 bubbles in their blood vessels

13. decompress the stomach with a nasogastric tube to reduced the chances of aspiration and to increase the lung compliance

14.  if there is bronchospasm, treat with inhaled short-term Beta II agonists.

15.  According to the AHI, deliberately placing a patient into hypothermia to decrease damage from tissue hypoxia has not been shown to be helpful in drowning. More research is needed. 

 

Suffocation/ asphyxiation

Patients who suffer asphyxia from upper airway obstruction due to immersion in solids such as grains actually suffer from suffocation, as do persons who have been subjected to strangulation or upper airway occlusion.

Naturally, the most serious immediate problem associated with suffocation by immersion in a solid is the profound hypoxemia & mixed acidosis, but the actual substances may cause other problems particularly if the substance was inhaled into the lungs and it is toxic.

An adult who has aspirated a foreign body that causes complete airway obstruction needs abdominal thrusts, followed by mouth sweeps and then attempts to ventilate alternating until the airway is clear.

In the infant, we give back blows followed by a mouth sweep only if the object is visible. We reestablish the airway, attempt to ventilate and continue back blows, and ventilation efforts until the object is removed.

Objects that result in partial airway occlusion could be dislodged from the main stem into the glottis by back blows, so these objects need to be removed by bronchoscope under controlled conditions. Let the patient attempt to cough these up without interference.