The Management of Drowning: Prognosis

It is difficult to prognosticate in individual cases because data from the literature, much of it in the paediatric age group, arise from widely different situations. These situations range from childhood bath and pool incidents in fresh water to boating, swimming and diving activities in the open sea. Nevertheless, several reasonably consistent observations emerge.

Factors that negatively affect outcome include submersion time, time to initiation of effective CPR, severe metabolic acidosis, Glasgow Coma Scale (GCS <5), cardiac arrest and the presence of fixed dilated pupils. However, complete recoveries have been reported despite the presence of one or more of these adverse predictors.

Poor prognostic factors

Prolonged submersion.Prolonged time to effective cardiopulmonary resuscitation.Cardiac arrest.Absence of spontaneous respiration.Prolonged coma.

Several pooled series indicate that 90 per cent of patients who arrive at least arousable with spontaneous respiration and purposeful response to pain will survive neurologically intact. In contrast, of the patients in this series who arrived comatose, 34 per cent died, and 20 per cent of the survivors had neurological damage18.

Unresponsive coma, decorticate and decerebrate rigidity, areflexia and fixed dilated pupils are not in themselves diagnostic signs of death, although they are, of course, signs of a poor prognosis. Patients who arrive in hospital in asystole usually have a poor prognosis, and one series reported a 93 per cent mortality rate after cardiac arrest. Current treatment regimens do not alter the outcome.

The rapid development of severe hypothermia, either before or during the final submersion, is probably protective and helps to explain some spectacular recoveries after prolonged periods of submersion. The role of the diving reflex remains controversial.

The Management of Drowning: Hospital (Emergency department/Intensive care)

Hospital management is subdivided into initial emergency department management and continuing therapy in the intensive care unit. All patients should receive oxygen (see Chapter 49) while undergoing evaluation.

Emergency department

On arrival, the emphasis is on evaluation and resuscitation of respiratory failure. Preliminary assessment includes airway, circulation and level of consciousness re-evaluation. Continuous monitoring of pulse, blood pressure, pulse oximetry and electrocardiography are commenced.

The severity of the case determines the appropriate care. If submersion victims show no signs of aspiration on arrival in the emergency department, there may be no need for hospital admission. Patients who are asymptomatic and have normal chest auscultation, chest x-ray findings and arterial blood gases will not subsequently deteriorate7–9. They may safely be discharged after 6 hours. In contrast, patients with mild hypoxaemia, auscultatory rales or rhonchi or chest x-ray changes should be admitted for observation because they may deteriorate.

In moderately hypoxaemic patients who have not lost consciousness and who are breathing spontaneously, the use of non-invasive ventilatory support with face mask or nasal continuous positive airway pressure (CPAP) may be an alternative to sedation and endotracheal intubation, provided adequate gas exchange is achieved.

Seriously affected patients should be admitted to an intensive care unit or a high-dependency unit. Patients with symptomatic hypoxaemia or disturbed consciousness may rapidly deteriorate further as a result of progressive hypoxaemia. Patients who have had a cardiac arrest or are unconscious and/or severely hypoxaemic require ventilatory support and should be intubated using a rapid sequence induction technique. A nasogastric tube should be inserted and the stomach emptied before induction, if possible.

Concurrent with resuscitation measures, a careful search for any other injuries, such as cranial or spinal trauma, internal injuries and long bone fractures, should be undertaken. Initial x-ray studies should include the chest and cervical spine. Cerebrovascular accident, myocardial infarction, seizure or drug abuse should be suspected if the cause of the incident is not readily apparent. One study revealed that 27 per cent of recreational diving deaths appeared to have a cardiac event as the disabling injury11, so a high index of suspicion for myocardial ischaemia should be maintained. A 12-lead electrocardiogram would be advisable early in the evaluation.

Similarly, in the scuba diver, other disorders such as pulmonary barotrauma and cerebral arterial gas embolism may have initiated or complicated the drowning. These conditions may require specific treatment such as recompression, hyperbaric oxygen or drainage of a pneumothorax. Nevertheless, it should never simply be assumed that a diver ‘must have’ suffered pulmonary barotrauma and arterial gas embolism just because the diver was brought to the surface rapidly or unconscious. There have been many unconscious ascents from significant depths in which it appears that pulmonary barotrauma did not occur. Moreover, such an assumption would indicate hyperbaric therapy. Although recompression should not be withheld from a patient who clearly warrants it, it is logistically difficult and more hazardous for an intensive care patient, and recompression should not be used speculatively.

The main goal of therapy is to overcome major derangement of hypoxaemia with its subsequent acidosis. The benchmark should be an arterial oxygen tension (PaO2) of at least 60 mm Hg. This may be achieved by administration of oxygen by mask in milder cases, possibly with CPAP, but some patients will require more aggressive therapy, employing intermittent positive pressure ventilation (IPPV) with a high fractional inspired oxygen concentration (FIO2).

High ventilatory pressures may be required to obtain adequate tidal volumes. Progress should be monitored by serial arterial blood gas determinations and continuous pulse oximetry.

The institution of continuous positive end-expiratory pressure (PEEP) with either IPPV or spontaneous ventilation, (i.e. CPAP) will decrease the pulmonary shunting and ventilation-perfusion inequality and increase the functional residual capacity, thus resulting in a higher PaO2. Nebulized bronchodilator aerosols may be used to control bronchospasm. In sedated patients, fiberoptic bronchoscopy can be used to remove suspected particulate matter, and repeated gentle endotracheal suction will assist in the removal of fluid from the airway.

Early on in the resuscitation sequence, large-bore intravenous access should be established and warmed crystalloid fluids commenced. Moderate volumes may be required initially because of tissue losses, immersion diuresis and dehydration, but care should be taken not to overhydrate. Simultaneously, blood for haematology and biochemistry laboratory work can be drawn for baseline assessment. Testing should include cardiac enzymes. Intra-arterial pressure monitoring is useful and allows frequent arterial blood gas determinations to guide ventilation and acid-base management.

If cardiac arrest is diagnosed, the rhythm should be rapidly determined, and defibrillation and/or intravenous adrenaline (epinephrine) should be administered according to advanced life support protocols (see Figure 23.3). Other arrhythmias should also be appropriately treated if they have not responded to correction of hypoxaemia and restoration of adequate tissue perfusion.

In the past, it was common to attempt to correct metabolic acidosis by giving bicarbonate. The use of bicarbonate in this setting is controversial, and some clinicians may prefer to hyperventilate a patient to create a respiratory compensation for the metabolic acidosis. A more modern alternative intravenous alkalinizing agent is tromethamine acetate (tris-hydroxymethyl aminomethane [THAM]). THAM has the apparent advantage that its action does not result in the generation of carbon dioxide (as occurs with sodium bicarbonate), and as such it may be a better choice in hypercapnic patients who have mixed acidaemia or in patients who are difficult to ventilate. These descriptors may apply to drowning victims.

Some drowning victims have been noted to be markedly hypoglycaemic, and an association with alcohol intoxication, physical exhaustion and hypothermia is relevant. Blood glucose concentrations should be rapidly determined along with blood gases on arrival at hospital, and intravenous glucose therapy should be instituted if appropriate. Untreated hypoglycaemia may aggravate hypoxic brain lesions. However, intravenous glucose must be used with care because hyperglycaemia is also potentially harmful to injured neurons. Hyperglycaemia resulting from massive catecholamine release or other causes may require insulin infusion.

Hypothermia may complicate drowning and pose difficulties with resuscitation end points in the event of cardiac arrest (see Chapter 28). The emergency department management of hypothermia depends on severity, and low-reading thermometers are required because severe hypothermia may otherwise be overlooked. Warmed intravenous fluids and inspired gases, insulation, forced-air warming blankets and radiant heat may be sufficient, but in severe cases, gastric lavage, peritoneal lavage or even cardiopulmonary bypass has been employed. Resuscitation should continue at least until core temperature approaches normal. Care should be taken to avoid hyperthermia because even mild degrees of cerebral hyperthermia can be profoundly disadvantageous to the injured brain.

Hypovolaemia may result from the combined effects of immersion diuresis and pulmonary and tissue oedema. Circulatory support maybe required to provide adequate perfusion of vital tissues. The maintenance of effective cardiac output may require the correction of hypovolaemia, which may be unmasked by the instigation of body rewarming. PPV also decreases venous return to the heart and thus lowers cardiac output. This can usually be overcome by volume restoration or even augmentation. If after volume replacement the patient does not rapidly regain adequate cardiac output, then inotropic support will be required.

Although not studied specifically in the context of drowning, there is compelling evidence from large randomized studies suggesting that resuscitation of intensive care patients with crystalloid fluids results in better outcome (and less requirement for renal replacement therapy) than does resuscitation using colloids. If colloids are used, small volumes of concentrated albumin may be optimal. Care must be taken not to overhydrate drowning patients.

Once intravascular volume is normalized and adequate cardiac output is established, fluid administration should be parsimonious. Diuretics (e.g. frusemide) have also been employed where overhydration is suspected. A urinary catheter with hourly output measurements is essential to determine renal perfusion and function and is a good indication of adequate volume. Electrolyte disturbances are usually not a significant problem in the initial phases, but any abnormality should be corrected.

Antibiotics given prophylactically are of dubious benefit. Antibiotics should be employed only where clearly clinically indicated, guided by sputum and blood cultures. Routine use may encourage colonization by resistant organisms.

Intensive care

The general principles of intensive therapy are followed, but with special emphasis on respiratory function because near drowning is a common cause of the acute respiratory distress syndrome (ARDS).

The following clinical parameters, established on arrival in the emergency department, should be regularly monitored:

  1. Routine clinical observations such as pulse, blood pressure, temperature, respiratory rate, minute volume, inspiratory and PEEP pressures, electrocardiography, pulse oximetry and urine output.
  2. Where indicated, invasive monitoring such as central venous pressure, pulmonary artery wedge pressure and cardiac output by a pulmonary artery catheter.
  3. Blood tests such as arterial blood gas and acid-base status, haemoglobin, packed cell volume, white cell count, serum and urinary electrolytes, serum and urinary haemoglobin and myoglobin levels, serum creatinine, urea, glucose, protein and coagulation status.
  4. Regular chest x-ray examination to detect atelectasis, infection, pneumothorax, pulmonary oedema, pleural effusions and other disorders.
  5. Serial measurement of pulmonary mechanics, by measurement of airway pressures and compliance, which are also useful in monitoring progress. In the less severely ill patient, simple spirometry is a useful guide to recovery.

The optimal method of ventilation aims to produce an adequate oxygen tension at the lowest FIO2 (preferably FIO2 of 0.6 or less to avoid pulmonary oxygen toxicity; see Chapter 17) with the least haemodynamic disturbance and the least harm to the lung. CPAP can be dramatic in improving oxygenation by reducing intrapulmonary shunting. Pressures of 5 to 10 centimetres of water are usual, but greater pressures may be required. Patients receiving PPV tend to retain salt and water, so fluid intake should be reduced to about 1500 ml/day with low sodium content. Fluid overload may have a deleterious effect on pulmonary function.

Various modes of ventilation have been employed. These include spontaneous respiration with CPAP, IPPV with and without PEEP, synchronous intermittent mandatory ventilation, pressure support and high-frequency ventilation. Increasing experience in the management of ARDS has led to the development of so-called ‘lung protective ventilator strategies’ characterized by relatively long inspiratory times, high end-expiratory pressures and relatively small tidal volumes. This may require acceptance of both a degree of ‘permissive hypercapnia’ and mild respiratory acidosis that in the short term may be treated with bicarbonate or THAM, before medium-term compensation through renal retention of bicarbonate. Postural changes (e.g. prone ventilation) are sometimes experimented with in individual patients. There is no universally applicable formula for ventilating these patients, and much individualization of regimens occurs in high-level intensive care units. These types of strategy may be necessary in severely affected drowning victims.

Femoro-femoral or full cardiopulmonary bypass has been employed both for rewarming hypothermic patients and for establishing adequate oxygenation in severe cases12. Severe ARDS has been successfully managed with variable periods (up to weeks) of extracorporeal membrane oxygenation (ECMO).

Because of improvements in cardiorespiratory support, preservation of the central nervous system is now the major therapeutic challenge13. The application of various brain protection techniques including deliberate hypothermia, hyperventilation, barbiturate coma and corticosteroids has not altered cerebral salvage rates in the specific context of drowning14,15. Studies in community cardiac arrest do provide circumstantial support for the use of hypothermia after prolonged resuscitation. Although some intensive care units may try this in drowning victims, it is certainly not considered a standard of care. It is notable that corticosteroids have not been shown to reduce cerebral oedema or intracranial pressure (ICP) and are not recommended.

Central nervous system function is assessed clinically and potentially by electroencephalography. ICP monitoring has been advocated where intracranial hypertension is suspected, with prompt therapy for any sudden elevation.

Serial creatinine estimations often reveal mild renal impairment in patients requiring intensive care. Severe acute renal failure16 requiring dialysis is less common, but it may develop in patients who presented with severe metabolic acidosis and elevated initial serum creatinine levels. Occasional cases of rhabdomyolysis have also been reported.

Hyperpyrexia commonly follows drowning, and its effect may be deleterious, especially to the injured brain. External cooling and antipyretic drugs to prevent shivering and to keep the temperature lower than 37°C may be indicated.

Continuing hyperexcitability and rigidity may require the use of sedative and relaxant drugs.

The Management of Drowning: Advanced Life Support and Transport

A regional organized emergency medical service (e.g. paramedics) that carries specialized apparatus such as oxygen, endotracheal tubes, suction and intravenous equipment should be activated, if available. In any case, the patient should be transferred to hospital as soon as possible. The early administration of oxygen by suitable positive pressure apparatus, by personnel trained in its use, may be the critical factor in saving lives. For this reason, oxygen administration equipment should be carried on all dive boats. Patients who regain consciousness or who remain conscious after drowning events may have significant pulmonary venous admixture with resultant hypoxaemia. All such patients should receive supplementary oxygen and be further assessed in hospital. Respiratory and cardiac arrests have occurred after apparently successful rescue.

Although endotracheal intubation remains the best method for securing an airway and achieving adequate ventilation, the necessary expertise may not be available until the victim is transferred to hospital. In such cases, the use of airway devices such as the laryngeal mask airway may improve ventilation while the patient is being transported to hospital. Other airways such as the pharyngo-tracheal lumen airway and the Combitube tube are alternatives, but they require more training and have their own problems. One potential problem with all supraglottic devices, and with mouth-to-mouth and bag-mask ventilation techniques for that matter, is that the airway pressures required to inflate a ‘wet’, non-compliant lung may be very high and not easily achieved with these devices or methods. Endotracheal intubation may the only way to achieve adequate tidal volumes in such patients.

Properly trained and equipped personnel attending a case in the field may be able to invoke advanced resuscitation techniques such as the airway interventions mentioned earlier and the monitoring methods, drug administration strategies and arrhythmia treatments specified in Figure 23.3.

Advanced life support algorithm. CPR, cardiopulmonary resuscitation; ECG, electrocardiogram; ETT, endotracheal tube; IV, intravenous; IO, intra-osseous; LMA, laryngeal mask airway. (From the Australian Resuscitation Council.)
Advanced life support algorithm. CPR, cardiopulmonary resuscitation; ECG, electrocardiogram; ETT, endotracheal tube; IV, intravenous; IO, intra-osseous; LMA, laryngeal mask airway. (From the Australian Resuscitation Council.)

Advanced life support algorithm. CPR, cardiopulmonary resuscitation; ECG, electrocardiogram; ETT, endotracheal tube; IV, intravenous; IO, intra-osseous; LMA, laryngeal mask airway. (From the Australian Resuscitation Council.)

The Management of Drowning: Rescue and initial resuscitation

In the diving setting, the management of a drowning situation often begins with witnessing a diver become unconscious underwater. Before resuscitation efforts can begin, the victim must be retrieved to the surface. Related considerations were reviewed by the Undersea and Hyperbaric Medical Society (UHMS) Diving Committee1, and their findings are outlined here.

The overarching goal of this initial phase of the rescue is to retrieve the diver to the surface as quickly as possible, even if the victim has a mouthpiece in place and appears to be breathing (which would be a most unusual circumstance). More typically, the victim is found unconscious with the mouthpiece out. No attempt should be made to replace it; however, if the mouthpiece is retained in the mouth, then the rescuer should make an attempt to hold it in place during the ascent. An ascent should be initiated immediately. If there is significant risk to the rescuer in ascending (if the rescuer has a significant decompression obligation), then making the victim buoyant and sending him or her to the surface may be the only option, depending on the degree to which the rescuer wishes to avoid endangering himself or herself.

The committee flagged one exception to the advice to surface immediately. In the situation where a diver is in the clonic phase of a seizure with the mouthpiece retained, then the mouthpiece should be held in place and ascent delayed until the seizure abates. To be clear, however, this does not apply to the more common situation of the seizing diver whose mouthpiece is out. In the latter situation, the ascent should be initiated while the diver is still seizing. This dichotomy arises because of the committee’s perception of the shifting balance of risk between pulmonary barotrauma and drowning in situations where the airway is at least partially protected or not. Thus, where the airway is completely unprotected (mouthpiece not retained), the risk of drowning outweighs the risk of barotrauma imposed by seizure-induced apposition of the glottis tissues. Where the airway is partly protected (mouthpiece retained and held in place), the opposite holds true. This matter is discussed in more detail in the committee report.

At the surface, the victim should be made positively buoyant face-up, and a trained rescuer should attempt to give two mouth-to-mouth rescue breaths. Experience has shown that this is often all that is required to stimulate the victim to breathe. Pausing to give rescue breaths will slightly delay removal from the water for definitive cardiopulmonary resuscitation (CPR) and is therefore a gamble that the victim has not yet having suffered cardiac arrest. However, given the extremely poor outcome expected if a drowning victim suffers a hypoxic cardiac arrest and the time it usually takes to remove a diver from the water, the committee determined that this was a gamble worth taking. The best chance of survival lies in preventing hypoxic cardiac arrest, and establishing oxygenation is the means of such prevention. If the diver has already had a cardiac arrest, then a small extra delay in initiating CPR imposed by performing in-water rescue breaths is not likely to alter the outcome. There is some human evidence suggesting a survival advantage for in-water rescue breathing in non-diving drowning situations2.

Once at the surface and in a situation where the surface support is not immediately to hand, a choice must be made whether to wait for rescue or initiate a tow to shore or nearest surface support. The committee determined that if surface support is less than a 5-minute tow away, then a tow should be commenced with intermittent rescue breaths administered if possible. If surface support or the shore is more than a 5-minute tow away, then the rescuer should remain in place, continuing to administer rescue breaths for 1 minute. If there is no response in this time, then a tow toward the nearest surface support should be initiated without ongoing rescue breaths. These guidelines are summarized in Figure 23.1.

Undersea and Hyperbaric Medical Society Diving Committee guidelines for rescue of an unresponsive diver from depth.
Figure 23.1 Undersea and Hyperbaric Medical Society Diving Committee guidelines for rescue of an unresponsive diver from depth. It is recommended that the interested diver read the original paper which contextualizes these recommendations more thoroughly. CPR, cardiopulmonary resuscitation. (From Mitchell SJ, Bennett MH, Bird N, Doolette DJ, et al. Recommendations for rescue of a submerged unconscious compressed gas diver. Undersea and Hyperbaric Medicine 2012;39:1099–1108.)

It is notable that these guidelines contain no reference to in-water chest compressions. Although techniques for in-water chest compressions have been described3,4, the committee did not consider there was adequate evidence of efficacy to justify the extra difficulty and stress to the rescuer for their inclusion in the rescue protocol.

The victim should be kept horizontal as much as possible during and after removal from the water. The patient should be moved with the head in the neutral position if cervical spine injury is suspected. Scuba divers are most unlikely to have suffered cervical spine trauma. A basic life support algorithm should be initiated immediately, beginning with assessment of the airway (Figure 23.2).

Basic life support algorithm. AED, automatic external defibrillator; CPR, cardiopulmonary resuscitation. (From the Australian Resuscitation Council.)
Figure 23.2 Basic life support algorithm. AED, automatic external defibrillator; CPR, cardiopulmonary resuscitation. (From the Australian Resuscitation Council.)

AIRWAY

Vomiting and regurgitation frequently follow a submersion incident. Foreign particulate matter causing upper airway obstruction should be removed manually or later by suction. Obstruction of the upper airway by the tongue is common in the unconscious patient.

Two methods are used to overcome the obstruction:

Head-tilt/chin-lift is accomplished by pushing firmly back on the patient’s forehead and lifting the chin forward by using two fingers under the jaw at the chin. The soft tissues under the chin should not be compressed, and unless mouth-to-nose breathing is to be employed, the mouth should not be completely closed. This technique should be avoided if cervical spine injury is suspected.

Jaw-thrust describes the technique of forward displacement of the lower jaw by lifting it with one hand on either side of the angle of the mandible. Unless cervical spine injury is suspected, this technique is often combined with head-tilt.

Time should not be wasted in trying to clear water from the lower airways. If airway obstruction is encountered and has not responded to normal airway management, the Heimlich manoeuvre (sub-diaphragmatic thrust) has been suggested5. This manoeuvre, which was proposed as a routine step to clear water from the airway, has not received the widespread endorsement of resuscitation councils around the world. It should be used with caution and only as a last resort because of the risks of regurgitation of gastric contents, rupture of the stomach and causing delay in initiating effective ventilation. Persistent airway obstruction may result from a foreign body, but other causes include laryngeal oedema or trauma, bronchospasm and pulmonary oedema.

BREATHING

Respiration can be assessed by placing one’s ear over the victim’s mouth while looking for chest movement, listening for air sounds and feeling for the flow of expired air. If breathing is detected, oxygen should be administered and the victim maintained in the ‘recovery’ position to avoid aspiration of fluid or vomitus.

If breathing is absent, mouth-to-mouth or mouth-to-nose breathing is instituted. Initially, two full breaths of air, with an inspiratory time (for the victim) of 1 to 1.5 seconds, are recommended. For adults, an adequate volume to observe chest movement is about 800 ml. If no chest movement is seen and no air is detected in the exhalation phase, then head-tilt or jaw-thrust manoeuvres should be revised. Failing that, further attempts at clearing the airway with the fingers (only if the victim is unconscious!) should be undertaken. With mouth-to-mouth respiration, the rescuer pinches the victim’s nose and closes it gently between finger and thumb. Mouth-to-nose rescue breathing may be more suitable in certain situations, such as when marked trismus is present or when it is difficult to obtain an effective seal (e.g. injury to mouth, dentures).

Paramedics or other practitioners with advanced skills are likely to use a bag-mask-reservoir device connected to an oxygen source for manual positive pressure ventilation in the field. Useful adjuncts in resolving upper airway obstruction may include a nasopharyngeal airway, oropharyngeal airway or supraglottic airway device such as a laryngeal mask. Endotracheal intubation in the field should be undertaken only by highly trained and experienced practitioners.

The rate of chest inflation should be about 12 per minute (one every 5 seconds) with increased rate and decreased volume in young children.

It must be made clear that the recent advocacy for ‘compression-only CPR’ in which rescue breathing is omitted and first responders provide only chest compressions to victims of community cardiac arrest is not relevant to CPR in the context of drowning.The cause of cardiac arrest in the community is usually some sort of cardiac disease, whereas it is hypoxia in drowning. Compression-only CPR works in community cardiac arrest because the victim is not hypoxic at the onset of cardiac standstill, and the lungs are filled with air to functional residual capacity. In contrast, hypoxia is usually the cause of cardiac arrest in drowning, and the lungs are frequently compromised by aspirated fluid and alveolar collapse. Failing to ventilate the lungs during resuscitation of a drowning victim is likely to bias against a good outcome.

CIRCULATION

The presence of a carotid or femoral pulse should be sought in the unconscious non-breathing victim. This is often difficult because the patient is usually cold and peripherally vasoconstricted. Although it is possible that external cardiac compression (ECC) could precipitate ventricular fibrillation in a hypothermic patient, if in doubt it is safer to commence ECC than not.

If no carotid pulse is detected, ECC should be commenced after two initial breaths. Higher rates of compression are now recommended, with greater outputs achieved at 100/minute compared with the traditional 60/minute standard. Controversy still exists over the mechanism of flow in external compression, with the evidence for the older ‘direct compression’ model being challenged by the ‘thoracic pump’ theory.

Cardiac compression should be performed with the patient supine on a firm surface. The legs may be elevated to improved venous return. The rescuer kneels to the side of the patient. The heel of the rescuer’s hand should be placed in line with the patient’s sternum. The lower edge of the hand should be about two fingers above the xiphisternum (i.e. compression is of the lower half of the sternum). The second hand should be placed over the first, and the compression of the sternum should be about 4 to 5 centimetres in adults in the vertical plane. To achieve this, the rescuer’s elbow should be straight, with the shoulders directly over the sternum. A single rescuer may be able to achieve rates of only 80/minute because of fatigue, but if several rescuers are present, it may be possible to maintain high rates.

Further help should be sought immediately, by a third person, if possible, without compromising resuscitation efforts.