Airway

The airway should be checked for foreign material and suction performed under direct vision. A look, listen and feel process will allow assessment of airway patency and respiratory effort. Basic airway manoeuvres such as a jaw thrust will be useful, whereas chin-lift and head-tilt should be reserved for patients with a clear history of non-trauma.

Clearance and maintenance of a patent airway, preferably by the most definitive means available, are of primary importance. Ideally this would be by either immediate intubation with a cuffed endotracheal tube or a rapid sequence induction (RSI). If this skill is not immediately available, time should not be wasted making several attempts at this while the patient becomes more hypoxic. A suitable alternative may be a laryngeal mask airway (LMA), although there is an increased risk of aspiration of gastric contents, particularly in drowning patients who may have swallowed copious amounts of water. Newer versions of the LMA with an embedded channel for a gastric tube may facilitate safer airway management utilising suction aspiration of stomach contents.

Manual in-line immobilisation should be employed during airway management if there is a history or a suspicion of trauma, particularly in diving accidents. Adjuncts such as rigid cervical collars, sandbags and tape assist in immobilising an at-risk cervical spine, although their limitations should be known, particularly in children where an immobilised and

Figure 29.1 Drowning algorithm

restrained head and neck may lead to a mobile body. Care must be taken not to manage a potential cervical spine injury to the detriment of efficient airway management.

Breathing

Adequate oxygenation and ventilation are required to reverse hypoxia and acidosis, which may have a mixed respiratory and metabolic aetiology. If the patient is conscious and the airway is protected, apply high flow oxygen at 15 L min^–1 via a non-rebreather mask. Unconscious patients with definitive airway management in situ should have an initial FiO₂ of 1.0 maintained. If patients are obtunded, management of the airway is essential as described above. The potential for aspiration is high in drowning patients due to swallowed water, and a low threshold must be maintained for RSI and intubation.

Awake patients with adventitious signs in their chest suggesting aspiration or acute pulmonary oedema may benefit from non-invasive ventilation (NIV), delivered as either continuous positive airway pressure (CPAP) or bi-level positive airway pressure (BiPAP), which has been shown to be effective at reducing mortality and preventing intubation in selected other patient groups. Although ‘fluid overload’ may be possible in drowning victims, which would mandate loop diuretics such as frusemide for treatment of symptoms and signs of pulmonary oedema, the probable cause is more likely to be hypoxia- and acidosis-induced acute myocardial dysfunction with fluid maldistribution, and therefore NIV and potentially high-dose nitrate infusion may be the most appropriate treatment.

Conscious patients should be monitored by means of continuous pulse oximetry, and ideally side-stream end-tidal CO₂ (EtCO₂) monitoring may give evidence of hypoventilation. This equipment is not common; however, it has been shown to be efficacious in monitoring patients at risk for compromised ventilation. Ventilated patients should routinely have EtCO₂ monitored and ventilation titrated to allow maximum cerebral perfusion; in the presence of head injury, maintenance of EtCO₂ at 35 mmHg is appropriate.

Indications for RSI and intubation may be:

Intubated patients should have an orogastric tube inserted to treat intragastric swallowed fluid and air. Have a high index of suspicion for tension pneumothorax if there is hypotension resistant to fluid resuscitation, particularly in the setting of potentially serious trauma associated with drowning. Small pneumothoraces may be managed by observation; however, if patients are intubated and ventilated, positive pressures may turn a simple pneumothorax into a tension pneumothorax, and placement of intercostal catheters may be an early necessity.

Circulation

Patients in cardiac arrest following drowning who require basic or advanced life support and are not hypothermic have a poor prognosis. Routine BLS/ALS should be implemented.

Cardiac arrhythmias are secondary to hypoxia, acid–base disturbance and hypothermia, rather than electrolyte disturbances secondary to massive fluid aspiration, and any type of cardiac arrhythmia may be observed, particularly bradycardia and atrial fibrillation which are statistically the most common abnormalities.

Venous access should be urgently obtained with a large-bore cannula. Cardiac arrhythmias should be treated according to ALS algorithms. Boluses of crystalloid or colloid fluid are useful in maintaining perfusion of vital organs, although importantly attempts should not be made to attain ‘normal’ blood pressures, particularly in the presence of potential serious trauma or covert blood loss. A mean blood pressure of 65 mmHg will be sufficient to maintain cerebral and renal perfusion.

Rewarming is essential (see the ‘Hypothermia’ section in Chapter 32): wet clothing should be removed, the skin should be dried and the patient should be wrapped in warm blankets with aluminium foil outside this. Intravenous fluids should be warmed to 40°C; ventilator circuits should contain a humidifier/warmer to ensure ventilatory gases are also close to body temperature. Children lose heat quickly due to the large surface area:body mass ratio and therefore careful management of temperature is mandatory.

A low threshold for intraosseous cannulation should be maintained, especially in cardiac arrest or critical condition post drowning; this may be achieved in adults as well as children. Care should be taken with central venous cannulation as the hypothermic myocardium may be sensitive and prone to dysrhythmias. Rescuscitation should not be ceased until the core temperature is above 30°C, and there are still no signs of life or organised cardiac function.

Dysfunction

Cerebral function is best preserved by prompt and effective management of airway, breathing and circulation. Neurological observations and sequential recording of GCS monitors trends.

Exposure and everything else

Drowning patients need to be fully exposed to assess for injuries and potential related or causative factors. Remove all wet clothing and dry the patient, then promptly cover with blankets/space blankets as previously described to retain heat and to start or continue the process of rewarming. Core temperature should be recorded, and an indwelling temperature probe and urinary catheter should be inserted during this part of the examination. A log-roll should be performed to ensure that there are no missed injuries bearing in mind that in unconscious patients, particularly those retrieved from inland waterways, beaches etc, there is a high risk of concomitant spinal injury, and taking particular care of airway adjuncts that have already been inserted. This means that manual in-line immobilisation (MILS) should be maintained until subsequent imaging, ideally using a CT scan of the entire spine, is performed and interpreted by an appropriately trained clinician. Log-rolling should be performed using a controlled spinal technique, ideally a ‘three under, three over’ method that prevents pelvic tilting and lateral flexion of the spine. Appropriate imaging should be performed at this stage, including a chest X-ray, and a pelvic X-ray if serious trauma is suspected as part of a mechanism of injury prior to drowning.