Ventilation during adult cardiopulmonary resuscitation (CPR) is poorly understood. Therefore, guideline recommendations are limited. The use of waveform capnography is in part recommended to monitor frequency. Other ventilation measurements such as tidal volume or inspiratory pressure are not regularly obtained, especially when a bag-valve system is used. The use of new monitoring devices can improve guideline adherence and could lead to better understanding of ventilation during CPR. Different EMS systems have varying levels of training, equipment and resources during CPR of out-of-hospital cardiac arrest (OHCA) patients. To better understand the current state of ventilation monitoring during OHCA CPR researcher/practitioner feedback and international perspectives on this question are needed and very much appreciated.
The evidence in this domain is poor. I monitor respiratory rate, end tidal carbon dioxide, blood gases and lactate. I also perform echocardiography during pulse checks.
Our EMS system currently only monitors ventilator rate, waveform capnography, and pulse oximetry. In the next 6 months we are budgeting to get upgrades in our monitors to actively measure and give real time feedback on tidal volumes and ventilator rates. We believe in the saying of “death by hyperventilation“.
There is also good research showing that hyperventilating traumatic brain injured patients decreases survival. Article Association of Statewide Implementation of the Prehospital T...
To be frank and very pragmatic. OHCA or for those whom misunderstand the acronym "Out of hospital Cardiac Arrest" Is a vexed area of research.
Specifically nailing down "cause and effect" and validating any process or procedure falls fowl of ethics, standardised practices including equipment, measures, procedures and finally training and levels of experience of individual practitioners.
So in my current roles as both a Critical care paramedic and in aeromedical retrieval our metrics vary.
Our basic measures include only Vt as a graphic based on EtCo2 wave form and rate which is variable depending on age and procedures being conducted at the time.
I work in a large statutory service in a large state in Australia, so we follow the ILCOR/ARC guidelines for management but we have no guidelines for "measurement" other than the metrics such as depth and rate of compression.
If we are successful in achieving sustained ROSC ( return of spontaneous circulation) then ventilation in the out-of-hospital setting is roughly 12 / min rate, with a volume based on that of the adult BVM ( usually 350-550 ML) and hand pressures or "feel" along with visual ques such as chest rise and fall, breath sounds and metrics such as pulse oximetry and capnography.
E.G oximetry low = increase FiO2 but it's usually always set to high flow and > 0.9. specially after prolonged down times > 10 min)
As for capnography well that depends ? depends on the comorbidities, nature of the cardiac arrest ( traumatic vs Cardiogenic) and whether the patient is intubated/advanced airways or not.
Even then it may be a case of permissive hypercapnia or a judgment call in the case of head injuries or severe hypoxia where higher rates and positive end expiratory pressure (PEEP) and acidosis may indicate driving Co2 down to compensate if the patient is not already doing so as a function of physiological changes and an intact CNS/ANS.
We have not progressed to POC (point of care) testing blood gases in the field yet and we do FAST (Focused Assessment with Sonography in Trauma)scans to measure cardiac function or check for free fluid or pneumothorax but its vary rarely utilised in OHCA unless as an adjunct to trauma where tamponade is suspected.
We do manage empirical values after RSI ( rapid sequence intubation) for paralysed patients who are transitioned to Hamilton T2 ventilator and those metrics again are determined by the patient body habitus, comorbidity, age, height, and physiological values. But essentially, we watch and monitor for variations outside of acceptable parameters for each individual.
Sorry this has turned into a waffle but the simple answer is " It depends"
and it depends on a lot of things but is mainly limited to the equipment we carry or that is practicably able to be carried and the procedures which govern our management.
OUT OF HOSPITAL CARDIAC ARREST is messy. No matter how much we train, how many times we see it, and how many years we've been doing it, there is always someone in your team who's seeing it for the first time, or has a morbid fear, or has a different approach and equally there a no two situations the same. The environment and environmental factors such as time of day, location, and scene safety also modify what and how we do business.
Hope this helps
Jon
The usual thing is to use the following parameters in mechanical ventilation: Tidal volume: 7-10 ml/kg, Pressure peak 20-25, Respiratory rate 15 resp/min, I/E: ½, PEEP: 2-5 cmH2O, Pressure alarm: 35-40 cmH2O, FiO2: 1. All this, of course, due to the pathology and age of the patient. We have also the possibility to use capnography, pulse oximetry and the parameters and waveform of the ventilator. In this moment we are working in order to use a mobile laboratory for blood gases and lactate.
Waveform capnography is recommended whenever an advanced airway (SGA or tracheal tube) is used both during CPR and after ROSC
Current guidelines recommend giving the maximum feasible inspired oxygen during CPR based on the premise that restoring depleted oxygen levels and correcting tissue hypoxia improves survival.
During CPR, we monitor the end-tidal CO2 level to evaluate the ventilation quality. IF the CO2 is elevated, the patient is being hypoventilated. If the CO2 level is low, the patient is being hyperventilated.