The care for patients suffering from cardiopulmonary arrest in a context of a COVID-19 pandemic has particularities that should be highlighted. 
Any patient with suspected or confirmed COVID-19 who is at higher risk of acute deterioration or cardiopulmonary arrest should be appropriately flagged to Rapid Response Teams (RRT) or teams that, potentially, can carry out care. [2] [3] [4] [5] [6] Severity scores and attention code screening and triggering systems allow for the early detection of severe patients and can optimize any possible CPA care. [7] [8] [9] Potentially difficult laryngoscopy/tracheal intubation should be anticipated upon patient admission to hospital and/or Intensive Care Units (ICU) and be recorded on the patient chart. Scores such as MACOCHA (Table 1) or mnemonic ones, such as LEMON ("Look, Evaluate, Mallampati, Obesity/Obstruction and Neck") can help determine a difficult airway, and anticipate triggering support and request for difficult airway equipment. [3, 7, 8, [10] [11] [12] [13] [14] The MACOCHA score ranges from 0 (easy) to 12 (very difficult). A MACOCHA > 3 indicates difficult airway.
Considering therapies under assessment phase, such as, for example, chloroquine or hydroxychloroquine, and their potential risk of prolonging the QT interval in up to 17% of cases, it is essential to register the risk for severe polymorphic ventricular arrhythmias, especially torsades de pointes, and consequent CPA with shockable rhythms. [4, [12] [13] [14] [15] [16] [17] [18] [19] J o u r n a l P r e -p r o o f In this scenario, the patients at a higher risk associated with polymorphic tachycardia are the elderly, females, with COVID-19-associated myocarditis, or with cardiac failure, liver or kidney dysfunction, electrolyte disorders (particularly potassium and magnesium) or bradycardia. It is critical to identify patients that already have QT interval corrected (QTc), prolonged (superior to 500 ms) with daily ECG monitoring while taking drugs that can promote or accentuate such abnormality. [4, 12, 13, [18] [19] [20] When do we start cardiopulmonary resuscitation?
Decision making processes for starting CPR or not should continue to be on a case by case basis at pre-hospital care services, emergency departments and ICUs. Benefits to patient, safety and exposure of the team, and potential futility of maneuvers should be taken into account. CPR should always be performed, unless, previously defined guidelines indicate the contrary. [1, 2] "Do Not Resuscitate" (DNR) decisions/guidelines should be appropriately documented and conveyed to teams. Palliative and terminal care should follow local and institutional policies. [1] [2] [3] 
The precaution defined as STANDARD+AEROSOL is indicated for all resuscitation team members in order to assure adequate individual protection (according to patient with COVID-19 care guidelines) during CPR. The timely availability of Personal Protection Equipment (PPEs) packs, such as gowning items in the crash cart, will allow for less delay to start chest compressions and care continuity. [2, 4, [6] [7] [8] [9] The PPE pack should include: cap, N95 mask, protection goggles, face shield, impermeable gown, disposable elbow-length gloves and shoe covers. Even if there is a delay in starting chest compressions, team safety is a priority and appropriate use of PPEs is indispensable for those involved in CPA care. [2, 4, [6] [7] [8] [9] The number of professionals at point of care should also be reduced or restricted in this scenario, preferably not more than five individuals.
Hand hygiene has an important role in reducing transmission of COVID-19; it should be performed adequately, with soap and water (if soiled) or alcohol gel, for at least 20−30 seconds. [2, 16] Initial care J o u r n a l P r e -p r o o f CPA detection should follow the ILCOR/AHA and SBC standard recommendations, and starts by assessing responsiveness, breathing (only checking respiratory movements) and presence of central pulse. [1, 3] For adults, CPR should start by continuous chest compressions. If the patient still does not have an invasive/advanced installed airway (orotracheal tube, extra glottic device), a low flow oxygen mask or surgical mask, or sheet/towel over patient's mouth and nose should be maintained, until an invasive airway is installed; [12] chest compressions can trigger elimination of aerosols and should be started following the above recommendations.
CPR for children should be performed with chest compressions and lung ventilation with a Bag-Valve-Mask (BVM) device connected to a HEPA-High Efficiency Particulate Air filter until a definitive airway is obtained, given that CPA in pediatrics occurs, most of the time, due to a secondary respiratory cause and CPR only with chest compressions is less efficacious in this population. [1, 21, 22] If equipment is not available, a reasonable alternative is CPR only with chest compressions, keeping the patient with a surgical mask or sheet/towel over the mouth. [23] For pre-hospital CPA care, in the absence of a medical professional, hands-only CPR is recommended; the care described above on protection of patient's mouth to avoid aerosolization also remains recommended. [ 4, 9, 12, 13] Monitoring to determine rhythm/modality of arrest (shockable or non-shockable)
should be done as soon as possible as to not delay defibrillation of a shockable rhythm and the establishment of the appropriate algorithm. [1, 3] Airway access or other procedures should not postpone defibrillation of shockable-rhythms. [1, 3, 14] If a patient is wearing an oxygen face mask before CPA, keep it on until intubation, but without high flow oxygen (6−10 L.min -1 maximum) so as to not increase the risk of generating aerosol; if the patient is not with the airway device, the professional should put a surgical mask or sheet/towel over the victim's mouth and nose and perform continuous chest compressions.
Any reversible causes of CPA should be identified and treated before considering to interrupt CPR, particularly hypoxia, acidosis and coronary thrombosis, As hypoxia is considered one of the main causes of CPA in patients with COVID-19, invasive airway access should be the priority to isolate airways and decrease likelihood of aerosol generation, consequently, with less contamination of team and best ventilation/oxygenation standard. [15] [16] [17] [18] [19] During airway management, chest compressions should be interrupted to protect the team and we suggest managing airways during pulse presence checking to reduce interval without chest compressions.
Video laryngoscopy with a more acute angle shape blade should be the first choice for fast, safe and definitive airway access. In case of failure, help/support of a second physician should be requested immediately; upon a second attempt, video laryngoscopy again should be prioritized. [17] [18] [19] For children, it is recommended to perform the video laryngoscopy with a blade adequate to the child's age, with no requirement of more acute angulation. [23] In the impracticality or intubation failure, we recommend using extra glottic devices (laryngeal tube or laryngeal mask that enable orotracheal intubation using the device itself), that allow both mechanical ventilation using closed-circuit and capnography, until possibility of appropriate definitive airway access (tracheal intubation or cricostomy). [17] [18] [19] For children, the laryngeal mask adequate to the patient´s weight should be the extra glottic device preferably used. [23] In Brazil, insertion of extra glottic devices is within the scope of physicians and nurses, can be an option for securing airway, and can be performed by nurses at prehospital intermediate support units, provided they are properly trained for the procedure. [1, 3] 
Among extra glottic devices available, whenever possible, priority should be given to a device that offers higher airway sealing pressure and that can be used as a conduit that facilitates orotracheal intubation through it (LMA fast track or Air-Q). It is opportune to remember that with an extra glottic device, it is important to close and seal the patient´s mouth using towels, sponge gauzes or surgical masks to reduce aerosolization.
When CPA occurs in patients on mechanical ventilation, patient must be connected to ventilator, and a closed ventilation circuit used. Ventilator parameters should be set as follows:
-Volume, assisted-controlled mode, adjusted to 6 mL.kg -1 of predicted patient weight; J o u r n a l P r e -p r o o f -When using defibrillation, for team and patient safety, preferably always use adhesive paddles that do not require disconnection to ventilator to release shock. For manual defibrillation paddles, shock should be released after putting the ventilator on stand-by mode and disconnecting the breathing circuit from the ventilator at HEPA filter, keeping the filter connected to the orotracheal tube.
High quality chest compressions should be performed to guarantee: -If professionals understand the specificities of wearing PPE for aerosolization, the high physical demand of maneuvers, exhaustion potential, and need to minimize team present during resuscitation, we suggest using mechanical CPR devices for adults, if available.
If the patient is in prone position without an invasive airway installed, we recommend positioning the patient quickly into the supine position, establish CPR maneuvers, and install an invasive airway as soon as possible, preferably by orotracheal intubation.
If the patient is already intubated and on mechanical ventilation, it is recommended to begin cardiopulmonary resuscitation maneuvers with the patient still in prone; the reference point for placing hands follows the projection of the same place of chest compressions (T7-10 interscapular region) (Fig 4) . We recommend that attempts to resuscitate the patient be performed at maximum security when turning the patient, J o u r n a l P r e -p r o o f avoiding disconnection of the ventilator and risk of aerosolization. If adhesive defibrillator paddles are available, they should be adhered in the anteroposterior position ( Fig. 5) . [20, 21, 23, 24] If not available, defibrillation should be attempted putting the external paddle on the dorsal region and the apical paddle on patient's side. We recommend that efficacy of CPR be assessed using expired CO2 (PCO2 > 10 mmHg) and invasive blood pressure (considering diastolic pressure values over 20 mmHg). It is worth mentioning that evidence for this maneuver is still uncertain and, whenever possible turning from prone to supine position, more appropriate for high quality CPR and adequate ventilation, it should be carried out.
-Anticipate intensive care unit request for bed with respiratory isolation or cohort area before patient returns to spontaneous breathing. [1] [2] [3] 16, 18] -Dispose or clean all the equipment used during CPR, following manufacturer recommendations and local organization guidelines. [2] -Any surfaces used to place airway/resuscitation equipment will also have to be cleaned according to local guidelines. Check if equipment used to handle airways (laryngoscope, facial masks, for example) was not left on patient's bed. Try to leave equipment on a tray. [2, 14] -After care, doff PPE safely, avoiding self-contamination. [2, 16] Total attention should be given during this step, because most contamination of health professionals occurs at this point by contact with secretions and aerosols.
-CPR should not be initiated in the pre-hospital environment on patients with suspected or confirmed COVID-19 and obvious signs of death. [1, 3] -Professionals should follow standard+aerosol precaution for care of victims with suspected or confirmed COVID-19.
-Orient the population when calling 192, that they should inform if the victim is a suspected COVID-19 case; this will facilitate previous gowning of the care team. We suggest that telephone operators and regulators of emergency medical services carry out active search for these patients, asking about flu-like symptoms, fever, and dyspnea.
-Perform ongoing compressions. Mouth-to-mouth breathing and using a pocket mask should not be performed on patients with suspected or confirmed COVID-19. [2] J o u r n a l P r e -p r o o f -Taking into account that most out of hospital cardiorespiratory arrests occur at home, in the case of pediatric out of hospital CRA, lay emergency caregiver most probably is a member of the family or child caretaker, already in close contact with and exposed to secretions. In this case, the lay emergency caregiver should perform compressions and consider mouth-to-mouth breathing, if able and willing to do so, given most pediatric arrests are due to a respiratory cause. [23] CPR only with compressions is a reasonable alternative if emergency caregiver is not able to ventilate or has not been in previous close contact with the child. -CPR for children should preferably be performed with compressions and ventilations with a BVM attached to the HEPA filter.
-Pre-hospital airway management should follow the recommendations given above, as to assure that bag-valve-masks and other ventilation equipment are equipped with HEPA filters, and an advanced airway (orotracheal intubation or extra glottic device) is installed early.
-Open back doors of transportation vehicle and activate HVAC (heating, ventilation and air-conditioning) system during aerosol-generating procedures (perform procedure away from pedestrian traffic).
-Do not allow that accompanying individuals be taken in the same ambulance compartment of the patient. Patients with suspected or confirmed COVID-19 cannot risk company of contamination, according to Ministry of Health guidelines. We suggest that accompanying individuals be oriented to go to the reference health unit on their own for further information.
-If the vehicle does not have an isolated driver compartment, open external air exits in J o u r n a l P r e -p r o o f the driver area and turn on back exhaustion ventilators to a higher setting.
Debrief at the end of each procedure in order to provide improvements and team development. [1, 3] Training skills for correct gowning and, mainly, PPE doffing and CRA care drills should be performed as early as possible with all teams involved in care of patients with suspected or confirmed COVID-19. [16] [17] [18] [19] Training and continuous education are imperative (Figs. 6 and 7) , aimed at protecting teams and safer patient care. We strongly recommend using realistic drilling environment scenarios and at distance educational resources.
Institutional.
The authors declare no conflicts of interest.
Mallampati II or IV 5
Obstructive sleep apnea 2
Reduced cervical mobility 1
Mouth opening < 3 cm 1 Coma 1
Oximetry < 80% 1
Non-anesthetist physician 1