Remember that the evaluate, identify, intervene sequence of the systematic approach algorithm is essential for the management of each system during the post cardiac arrest phase. The following goals and interventions are carried out using this sequence from the systematic approach algorithm.
There are two goals that are included in respiratory management for immediate post-cardiac arrest care.
1. Maintain adequate oxygenation
2. Maintain adequate ventilation.
Critical to both of these goals is the maintenance of an open airway. One primary intervention to maintain an open airway during this phase is endotracheal intubation or the placement of some type of advanced airway.
- O2 saturation by pulse oximetry
- If intubated, ETCO2 by capnography
- Heart rate and respiratory rate
- Chest rise and fall
- Bilateral breath sounds
- ET tube position
- Signs of respiratory compromise: increased work of breathing, agitation, decreased responsiveness, cyanosis, etc.
- Arterial blood gas analysis
- Chest x-ray
When addressing the respiratory system, the questions that need to be asked continuously during the evaluate sequence of the systematic approach algorithm are:
1. Is there adequate oxygenation?
2. Is there adequate ventilation?
These two questions are answered by assessments that are carried out. These assessments include continuous monitoring, physical examination, and medical tests.
If the continuous evaluation indicates that the current interventions are adequate to maintain oxygenation and/or ventilation then the interventions will continue to be carried out.
If the continuous evaluation, at any time, indicates that the current interventions are inadequate to maintain oxygenation and/or ventilation then appropriate interventions will need to take place to correct the problem that is identified.
- After the return of spontaneous circulation, adequate oxygenation is maintained through the administration of high flow oxygen.
- If the patient is not intubated or receiving another form of non-invasive or invasive ventilatory support, high-flow oxygen would be supplied with a nonrebreathing mask.
- High flow oxygen is delivered to maintain an oxygen saturation ≥ 94% but < 100%. Effort should be taken to avoid hypoxemia and hyperoxia which can both have detrimental effects during the post cardiac arrest phase.
- If the child has an oxygen saturation < 90% and non-invasive (BiPAP) or invasive measures (ET tube placement) have not taken place they should be considered.
- Ventilation allows for both the delivery of oxygen into the lungs and also the removal of carbon dioxide out of the lungs. Both hypercapnia and hypocapnia should be avoided.
- Ventilations should be assisted as needed. Generally speaking, the PACO2 can be used to guide ventilations. Ventilations should be administered to target a normal PACO2 of 35 to 45 mmHg.
- Monitoring the removal of carbon dioxide (ETCO2) from the lungs is a highly effective way to determine the respiratory/ventilatory status during the post arrest phase.
- Once a patient has been intubated, sedation and analgesia become important factors to consider.
- Medications for pain control and sedation should be used to ensure the comfort and stability of the patient. Caution should also be used in the hemodynamically unstable patient.
- Another factor that should be considered is the use of paralyzing/neuromuscular blocking agents.
- Neuromuscular blocking agents can improve chest wall compliance, eliminate ventilator dyssynchrony, reduce intra-abdominal pressures, prevent and treat shivering, and prevent elevations in intracranial pressure (ICP) from airway stimulation.
- Neuromuscular blocking agents should always be used in conjunction with sedation and there should be an ongoing evaluation of sedation effects to ensure that children are neither over sedated nor under sedated.
- Some signs of inadequate sedation can be evaluated by looking for signs of stress such as tachycardia, hypertension, pupil dilation, and tearing.
Maintaining adequate oxygenation:
A special situation with oxygenation:
For children that are anemic (low hemoglobin), the oxygen carrying capacity will be decreased and therefore, a higher oxygen delivery dose (100% high flow) will be necessary to achieve an adequate level of oxygenation. If anemia is severe, it may be necessary to increase the hemoglobin level (blood transfusion) to improve oxygen delivery to the tissues. In cases where the hemoglobin is severely low, a pulse oximeter may reflect 100% oxygen saturation yet the oxygen delivery to the tissues will be insufficient because of the inadequate number of red blood cells carrying oxygen.
Maintaining adequate ventilation:
Special situations with ventilation:
Make sure to avoid hyperventilation of children with neurological problems unless the hyperventilation is being used to prevent impending cerebral herniation.
In emergencies involving respiratory failure and asthma, rapid correction of hypercapnia (high CO2) should be avoided and can possibly result in complications. When hypercapnia is rapidly corrected in certain types of respiratory failure this can lead to seizures and alkalemia. Also, efforts to achieve normocapnia with mechanical ventilation can result in pneumothorax.
Caution with ventilations should be taken in children with chronic respiratory conditions that are cared for emergently.
Both the physical assessment, continuous use of monitoring devices, appropriate medical test are essential for accurate and ongoing management of the respiratory system in the post cardiac arrest phase.