Feasibility of waveform capnography as a non-invasive monitoring tool during cardiopulmonary resuscitation

178 p.Sudden cardiac arrest (SCA) is one of the leading causes of death in the industrialized world and it includes the sudden cessation of circulation and consciousness, confirmed by the absence of pulse and breathing. Cardiopulmonary resuscitation (CPR) is one of the key interventions for patient survival after SCA, a life-saving procedure that combines chest compressions and ventilations to maintain a minimal oxygenated blood flow.To deliver oxygen, an adequate blood flow must be generated, by effective CPR, during the majority of the cardiac arrest time. Although monitoring the quality of CPR performed by rescuers during cardiac arrest has been a huge step forward in resuscitation science, in 2013, a consensus statement from the American Heart Association prioritized a new type of CPR quality monitoring focused on the physiological response of the patient instead of how the rescuer is doing.To that end, current resuscitation guidelines emphasize the use of waveform capnography during CPR for patient monitoring. Among several advantages such as ensure correct tube placement, one of its most important roles is to monitor ventilation rate, helping to avoid potentially harmful over-ventilation. In addition, waveform capnography would enable monitoring CPR quality, early detection of ROSC and determining patient prognosis. However, several studies have reported the appearance of fast oscillations superimposed on the capnogram, hereinafter CC-artifact, which may hinder a feasible use of waveform capnography during CPR. In addition to the possible lack of reliability, several factors need to be taken into account when interpreting ETCO2 measurements. Chest compressions and ventilation have opposing effects on ETCO2 levels. Chest compressions increase CO2 concentration, delivering CO2 from the tissues to the lungs, whilst ventilations remove CO2 from the lungs, decreasing ETCO2. Thus, ventilation rate acts as a significant confounding factor.This thesis analyzes the feasibility of waveform capnography as non-invasive monitoring tool of the physiological response of the patient to resuscitation efforts. A set of four intermediate goals was defined.First, we analyzed the incidence and morphology of the CC-artifact and assessed its negative influence in the detection of ventilations and in ventilation rate and ETCO2 measurement. Second, several artifact suppression techniques were used to improve ventilation detection and to enhance capnography waveform. Third, we applied a novel strategy to model the impact of ventilations and ventilation rate on the exhaled CO2 measured in out-of-hospital cardiac arrest capnograms, which could allow to measure the change in ETCO2 attributable to chest compressions by removing the influence of concurrent ventilations. Finally, we studied if the assessment of the ETCO2 trends during chest compressions pauses could allow to detect return of spontaneous circulation, a metric that could be useful as an adjunct to other decision tool

Feasibility of waveform capnography as a non-invasive monitoring tool during cardiopulmonary resuscitation

178 p.Sudden cardiac arrest (SCA) is one of the leading causes of death in the industrialized world and it includes the sudden cessation of circulation and consciousness, confirmed by the absence of pulse and breathing. Cardiopulmonary resuscitation (CPR) is one of the key interventions for patient survival after SCA, a life-saving procedure that combines chest compressions and ventilations to maintain a minimal oxygenated blood flow.To deliver oxygen, an adequate blood flow must be generated, by effective CPR, during the majority of the cardiac arrest time. Although monitoring the quality of CPR performed by rescuers during cardiac arrest has been a huge step forward in resuscitation science, in 2013, a consensus statement from the American Heart Association prioritized a new type of CPR quality monitoring focused on the physiological response of the patient instead of how the rescuer is doing.To that end, current resuscitation guidelines emphasize the use of waveform capnography during CPR for patient monitoring. Among several advantages such as ensure correct tube placement, one of its most important roles is to monitor ventilation rate, helping to avoid potentially harmful over-ventilation. In addition, waveform capnography would enable monitoring CPR quality, early detection of ROSC and determining patient prognosis. However, several studies have reported the appearance of fast oscillations superimposed on the capnogram, hereinafter CC-artifact, which may hinder a feasible use of waveform capnography during CPR. In addition to the possible lack of reliability, several factors need to be taken into account when interpreting ETCO2 measurements. Chest compressions and ventilation have opposing effects on ETCO2 levels. Chest compressions increase CO2 concentration, delivering CO2 from the tissues to the lungs, whilst ventilations remove CO2 from the lungs, decreasing ETCO2. Thus, ventilation rate acts as a significant confounding factor.This thesis analyzes the feasibility of waveform capnography as non-invasive monitoring tool of the physiological response of the patient to resuscitation efforts. A set of four intermediate goals was defined.First, we analyzed the incidence and morphology of the CC-artifact and assessed its negative influence in the detection of ventilations and in ventilation rate and ETCO2 measurement. Second, several artifact suppression techniques were used to improve ventilation detection and to enhance capnography waveform. Third, we applied a novel strategy to model the impact of ventilations and ventilation rate on the exhaled CO2 measured in out-of-hospital cardiac arrest capnograms, which could allow to measure the change in ETCO2 attributable to chest compressions by removing the influence of concurrent ventilations. Finally, we studied if the assessment of the ETCO2 trends during chest compressions pauses could allow to detect return of spontaneous circulation, a metric that could be useful as an adjunct to other decision tool

Waveform Capnography for Monitoring Ventilation during Cardiopulmonary Resuscitation: The Problem of Chest Compression Artifact

Sudden cardiac arrest (SCA) is the sudden cessation of the heart’s effective pumping function, confirmed by the absence of pulse and breathing. Without appropriate treatment, it leads to sudden cardiac death, considered responsible for half of the global cardiac disease deaths. Cardiopulmonary resuscitation (CPR) is a key intervention during SCA. Current resuscitation guidelines emphasize the use of waveform capnography during CPR in order to enhance CPR quality and improve patient outcomes. Capnography represents the concentration of the partial pressure of carbon dioxide (CO2) in respiratory gases and reflects ventilation and perfusion of the patient. Waveform capnography should be used for confirming the correct placement of the tracheal tube and monitoring ventilation. Other potential uses of capnography in resuscitation involve monitoring CPR quality, early identification of restoration of spontaneous circulation (ROSC), and determination of patient prognosis. An important role of waveform capnography is ventilation rate monitoring to prevent overventilation. However, some studies have reported the appearance of high-frequency oscillations synchronized with chest compressions superimposed on the capnogram. This chapter explores the incidence of chest compression artifact in out-of-hospital capnograms, assesses its negative influence in the automated detection of ventilations, and proposes several methods to enhance ventilation detection and capnography waveform

Liikkuva potilas: moniparametrisen hengitystaajuusmittauksen käyttökelpoisuus

Respiratory rate is one of the vital signs used to measure the body’s general physical health. Abnormal respiratory rate or a change in breathing frequency may indicate deterioration in the condition of a patient. Thus, respiratory rate measurement would benefit the mobile patients on general hospital wards where no continuous monitoring exists. This environment requests wireless and reliable respiratory monitoring that would be robust against motion artefacts that impede the reliability of common respiratory rate measurements currently available. Electrocardiography (ECG) and photoplethysmography (PPG) are common measurements in intensive care but also in sub-acute care setting. Respiration modulates the ECG and PPG waveforms in several ways that can be exploited to derive respiratory rate from these physiological signals. In ECG, the effect of breathing is seen as both amplitude and frequency modulation, whereas in PPG also baseline modulation is present. This thesis investigated the feasibility of ECG and pulse oximetry derived respiratory rate measurements during different activities and motion states. The performances of these derived methods were evaluated together with impedance pneumography and respiratory inductive plethysmography against capnography reference using statistical analysis. A major part of this thesis consisted of the data collection, signal processing and algorithm development required to create these derived methods. According to the results acquired, the use of ECG-derived respiration (EDR) methods based on QRS-amplitude as part of a multi-parameter respiratory rate algorithm would be feasible. However, all evaluated pulse oximetry derived respiration (PDR) methods were found to be unfit for use due to high susceptibility to motion artefacts. The development of a multi-parameter respiratory rate algorithm continues.Hengitystaajuus luetaan yhdeksi kehon yleisestä terveydestä kertovaksi vitaaliparametriksi. Epänormaali hengitystaajuus tai hengitystaajuuden muutos voi olla merkki potilaan kunnon huononemisesta ja siksi hengitystaajuuden seurannasta olisi hyötyä myös sairaaloiden vuodeosastoilla, missä potilaat liikkuvat ilman jatkuvaa valvontaa. Tällaisessa ympäristössä hengityksen seurannan tulisi toimia langattomasti ja luotettavasti. Monet yleisesti käytetyt hengitystaajuusmittaukset kärsivät kuitenkin liikkeen aiheuttamista häiriöistä, jotka heikentävät menetelmien luotettavuutta. Elektrokardiografia (EKG) ja fotopletysmografia (PPG) ovat yleisiä mittauksia myös tehohoidon ulkopuolella. Hengitys vaikuttaa näiden fysiologisten signaalien muotoon usealla tavalla, joita voidaan hyödyntää hengitystiedon johtamiseen näistä parametreistä. Sydänsähkökäyrän QRS-kompeksien amplitudi ja sykevälivaihtelu ovat yhteydessä hengitykseen samoin kuin fotopletysmografisen pulssiaallon perusviiva, amplitudi sekä pulssivälivaihtelu. Tässä diplomityössä tutkittiin EKG:stä ja PPG:stä johdettujen hengitystaajuusmittausten käyttökelpoisuutta erilaisissa liiketilanteissa. Näiden johdettujen menetelmien suorituskykyä verrattiin tilastollisen analyysin keinoin impedanssipneumografian ja hengitysinduktiivisen pletysmografian kanssa kapnografialla mitattuja vertailuarvoja vastaan. Työ koostui suurelta osin myös näiden menetelmien luomiseen vaaditusta aineiston keräämisestä, signaalinkäsittelystä sekä algoritmikehityksestä. Saatujen tulosten perusteella EKG:stä johdetut amplitudipohjaiset menetelmät olisivat hyödyllisiä moniparametrisessa hengitystaajuusmittauksessa käytettynä. Sen sijaan kaikki kehitetyt PPG:stä johdetut hengitystaajuusmenetelmät todettiin käyttökelvottomiksi liikkeen aiheuttamien häiriöiden vuoksi. Moniparametrisen hengitystaajuusmittauksen kehitystyö jatkuu