**4. Case study**

To illustrate and validate the foregoing theoretical discussion, a practical product development and management case study is presented here. This is from an earlier published research conducted by the author of this chapter.


*Review*

#### **In Situ Monitoring Systems of The SLM Process: On the Need to Develop Machine Learning Models for Data Processing**

#### **Pinku Yadav 1,2, Olivier Rigo 1, Corinne Arvieu 2, Emilie Le Guen 2 and Eric Lacoste 2,\***

Received: 27 May 2020; Accepted: 13 June 2020; Published: 18 June 2020

**Abstract:** In recent years, technological advancements have led to the industrialization of the laser powder bed fusion process. Despite all of the advancements, quality assurance, reliability, and lack of repeatability of the laser powder bed fusion process still hinder risk-averse industries from adopting it wholeheartedly. The process-induced defects or drifts can have a detrimental effect on the quality of the final part, which could lead to catastrophic failure of the finished part. It led to the development of in situ monitoring systems to effectively monitor the process signatures during printing. Nevertheless, post-processing of the in situ data and defect detection in an automated fashion are major challenges. Nowadays, many studies have been focused on incorporating machine learning approaches to solve this problem and develop a feedback control loop system to monitor the process in real-time. In our study, we review the types of process defects that can be monitored via process signatures captured by in situ sensing devices and recent advancements in the field of data analytics for easy and automated defect detection. We also discuss the working principles of the most common in situ sensing sensors to have a better understanding of the process. Commercially available in situ monitoring devices on laser powder bed fusion systems are also reviewed. This review is inspired by the work of Grasso and Colosimo, which presented an overall review of powder bed fusion technology.

**Keywords:** L-PBF; in situ sensing; quality assurance; machine learning


**2. Materials and Methods**

#### *2.1. Reagents and Materials*

Fluopyram (purity: 98%) was purchased from Sigma-Aldrich (St. Louis, MO, USA). The structure and physico-chemical properties of fluopyram are shown in Table 1 [10].

**Table 1.** Physico-chemical properties of fluopyram.

As a crop protection product, 40% suspension concentrate (SC) of fluopyram (Mercury, Bayer Crop Science Co., Ltd., Daejeon, Republic of Korea) was selected and purchased from a commercial agrochemical vendor. The analytical solvents, including acetonitrile and methanol, were purchased from J.T. Baker (Center Valley, PA, USA). High-performance liquid chromatography (HPLC) grade formic acid (purity: 99%) was purchased from Wako (Osaka, Japan) and ammonium formate (purity: ≥97%) was obtained from DAEJUNG (Siheung, Republic of Korea). Reagents used in the quick, easy, cheap, effective, rugged, and safe (QuEChERS) pretreatment method were purchased from Agilent Technology (Santa Clara, CA, USA). QuEChERS extract pouches (EN 15,662 method extraction kit; 4 g MgSO4, 1 g NaCl, 1 g sodium citrate dehydrate, and 0.5 g sodium hydrogencitrate

sesquihydrate) were used for partitioning, and dispersive solid phase extraction (d-SPE, 2 mL, 150 mg MgSO4 and 25 mg primary secondary amine (PSA)) was used for purification. A 100 mg/L stock solution was prepared by dissolving 10.20 mg of standard fluopyram (purity: 98%) in 100 mL of acetonitrile, and serially diluted using blank sample extracts to construct the matrix-matched working solutions at 1, 2, 5, 10, 20, 50, and 100 μg/L, which were used to correct for any matrix effects during the instrumental analysis. The stock and working solutions were stored at −20 ◦C in a freezer.


**5.1 Temporal change in CCl4 concentration in the aquifer**

The changes in CCl4 concentration in typical wells are presented in Table 4 and Fig.15. However, there is a general downward trend in concentration, CCl4 concentration in most of the wells increased in 2010. This may be due to the decrease in groundwater exploitation.

"n" is the number of the samples

Table 4. Summarizes of changes in the average CCl4 concentrations with time (μg/L)

The Fig. 15 shows that: (1) the CCl4 concentration in karst auifer has obvious seasonal variation. In general, CCl4 concentration of groundwater during the drought period from February to June is relative lower and during the rainy period from August to October is much higher. (2) CCl4 changes rapidly with time, which is notably different from the

Transport of Carbon Tetrachloride in a Karst Aquifer in a Northern City, China 447

common porous media aquifer. This may be due to the facts that: (1) The groundwater velocity in the aquifer is much higher than that in the porous media, which can reach 131.9m/h-3027.0 m/h. As a result, the advective flow dominates the movement of pollutant; (2) Local groundwater flow regime changed frequently. It was one of the important water supply source with over 80 wells owned by different departments for different purposes. Pump stopping and starting at different wells caused change in local flow field and subsequently cause change in CCl4 concentration; and (3) CCl4 transport channel is complex.

The non-parametric Mann-Kendall test was used to detect monotonic (increasing or decreasing) trends in time-series of CCl4 concentrations for the eight typical wells during the period 2004-2010. The Mann-Kendall test is widely used in environmental science for the detection of trends in time-series data. A 5% significance level was used to indicate statistically significant trends in the current study. The Mann-Kendall trend statistics (Z) indicates significant decreasing (Z <–1.96, p <0.05) and increasing (Z >1.96, p <0.05) trends. Table 5 presents that there are a highly significant decreasing trend in CCl4 in the karst aquifer and the decreasing trend in pollution source sub-area and the north sub-area area are more significant.

Well Time Z Trend

**5.3 Temporal change in CCl4 plume distribution**

was higher than that in the wells outside of the center.

than in length.

X-49 2004.02-2010.09 -4.35532 Decreasing, Significant X-62 2004.02-2010.09 -5.72119 Decreasing, Significant X-47 2004.02-2010.09 -4.74661 Decreasing, Significant X-83 2005.02-2010.09 -2.35838 Decreasing, Significant X-43 2004.02-2008.12 -3.38838 Decreasing, Significant X-59 2004.02-2010.09 -2.80019 Decreasing, Significant X-74 2004.02-2010.08 -4.67132 Decreasing, Significant X-56 2004.02-2010.09 -5.11015 Decreasing, Significant Table 5. The Mann-Kendall trend statistic (Z, p<0.05) in CCl4 concentration in typical wells

The Fig. 16 gives the change in CCl4 plume over time. In almost ten years, there was very little change in the distribution of CCl4 in the range of 3-10μg/L or 10-50 μg/L. There was a major reduction in the volume of groundwater containing concentrations between 50 and 300μg/L. The plume extended westward and eastward in northern sub-area to in the flood

Based on observed trends in the development of a plume, plumes can be grouped as four categories: expanding, stable, shrinking and exhausted (Rice at al., 1995). In this study, the length of pollution plume of CCl4 in the water-bearing aquifer was found to be stable while concentration is shrinking, which indicates that the plume decreased faster in concentration

Dynamic groundwater flow field is one of the most important factors controlling the CCl4 plume (Han et al., 2006). CCl4 plume in the aquifer is similar with the groundwater flow field, which is shown in Fig. 17. CCl4 diffusion was confined by higher water level around the plume (Zhu et al., 2008). The scope of seriously polluted wells was similar with the center of cone of depression. CCl4 concentration in the center of the local cone of depression

period every year. It should be noticed that the plume expanded eastward.

**5.2 Mann-Kendall trend tests**

Data sample collected

Fig. 15. The variation of CCl4 over time in typical supply wells

common porous media aquifer. This may be due to the facts that: (1) The groundwater velocity in the aquifer is much higher than that in the porous media, which can reach 131.9m/h-3027.0 m/h. As a result, the advective flow dominates the movement of pollutant; (2) Local groundwater flow regime changed frequently. It was one of the important water supply source with over 80 wells owned by different departments for different purposes. Pump stopping and starting at different wells caused change in local flow field and subsequently cause change in CCl4 concentration; and (3) CCl4 transport channel is complex.

## **5.2 Mann-Kendall trend tests**

446 Pesticides in the Modern World - Risks and Benefits

CCl4 (μg/L)

2004-2-19

CCl4 (μg//L)

04-2-19

2004-6-30

2004-10-19

05-2-21

2005-4-14

2005-5-31

2005-7-18

Fig. 15. The variation of CCl4 over time in typical supply wells

2005-8-22

2005-10-13

2005-12-6

2006-2-8

2006-4-7

2006-6-26

2006-10-10

2007-3-28

Data sample collected

2007-7-11

2007-9-24

2008-1-23

2008-6-13

2008-9-17

2009-1-19

2009-9-28

2010-5-7

2010-5-26

2010-7-2

2010-8-10

2010-9-17

2010-12-7

CCl4 (ug/L)

2004-3-11

2004-6-30

2009-9-25

2004-11-29

2005-2-16

2005-3-22

2005-4-28

2005-6-11

2005-7-15

2005-8-11

2005-9-6

2005-10-18

2005-11-30

2006-1-11

2006-3-2

2006-4-11

2006-7-18

2006-9-27

2007-2-13

2007-5-12

Data sample collected

2007-8-5

2007-9-17

2007-11-28

2008-3-24

2008-7-1

2008-9-5

2008-11-27

2009-4-21

2009-10-27

2010-5-4

2010-5-19

2010-6-8

2010-7-6

2010-8-6

2010-9-3

2010-9-30

2010-11-12

X--56

2010-12-17

CCl4(μg/L)

04-2-19

2004-7-16

2004-11-1

05-2-21

2005-4-14

2005-5-31

2005-7-21

2005-9-1

2005-10-27

2005-12-21

2006-2-22

2006-4-18

2006-8-1

2006-11-14

2007-4-27

Data sample collected

2007-8-13

2007-10-17

2008-3-14

2008-7-11

2008-10-17

2009-3-20

2009-11-22

2010-5-12

2010-6-8

2010-7-13

2010-8-20

2010-9-27

Well X-59

2010-11-17

2004-6-10

2004-9-13

2004-12-15

2005-2-28

2005-3-28

2005-5-17

2005-7-5

2005-7-29

2005-8-25

2005-10-8

2005-11-22

2006-1-6

2006-2-22

2006-4-11

2006-6-1

2006-9-27

2007-2-13

Data sample collected

2007-5-12

2007-8-13

2007-9-24

2007-12-11

2008-5-13

2008-8-1

2008-10-17

2009-2-20

2009-8-28

2010-4-28

2010-5-14

2010-6-4

2010-7-2

2010-7-30

2010-9-3

2010-9-30

Well X-61

2010-11-12

CCl4 (μg/L)

2004-2-19

2004-4-29

2004-7-8

2004-9-16

2004-11-25

2005-2-3

2005-4-14

2005-6-23

2005-9-1

2005-11-10

2006-1-19

2006-3-30

2006-6-8

2006-8-17

2006-10-26

2007-1-4

2007-3-15

2007-5-24

2007-8-2

Data sample collected

2007-10-11

2007-12-20

2008-2-28

2008-5-8

2008-7-17

2008-9-25

2008-12-4

2009-2-12

2009-4-23

2009-7-2

2009-9-10

2009-11-19

2010-1-28

2010-4-8

2010-6-17

2010-8-26

Well X-47

Well X-49

2010-11-4

The non-parametric Mann-Kendall test was used to detect monotonic (increasing or decreasing) trends in time-series of CCl4 concentrations for the eight typical wells during the period 2004-2010. The Mann-Kendall test is widely used in environmental science for the detection of trends in time-series data. A 5% significance level was used to indicate statistically significant trends in the current study. The Mann-Kendall trend statistics (Z) indicates significant decreasing (Z <–1.96, p <0.05) and increasing (Z >1.96, p <0.05) trends. Table 5 presents that there are a highly significant decreasing trend in CCl4 in the karst aquifer and the decreasing trend in pollution source sub-area and the north sub-area area are more significant.

Table 5. The Mann-Kendall trend statistic (Z, p<0.05) in CCl4 concentration in typical wells


**4.4 Inclusion criteria**

The inclusion criteria were all National Pharmaceutical Product Interface (NAPPI) codes. These are unique product identifier for a given surgical product, medical appliance, consumable product, pharmaceutical product or other medicinal product. The inclusion criteria were all NAPPI codes associated with a telephonic consultation consulting general medical practitioners. The ICD-10 code primary diagnosis was used to describe the diagnosis. The study mainly focused on outpatient patients with service dates between March and December 2020. A laboratory-confirmed (RT – PCR assay) COVID-19 was used to identify the COVID-19 case as per the World Health Organisation [17, 18] guidelines and definition. Inclusion criteria for COVID-19 admissions were patients that had a laboratory-confirmed (RT – PCR assay) COVID-19. An emergency ICD-10 code of U07.1 COVID-19, virus identified, is assigned to a diagnosis of COVID-19, confirmed by laboratory testing. An emergency ICD-10 code of 'U07.2' COVID-19, virus not identified, is assigned to a clinical or epidemiological diagnosis of COVID-19, where laboratory confirmation is inconclusive or not available. Both U07.1 and U07.2 may be used for mortality coding (cause of death).


*Metal Forming of Magnesium Alloys for Various Applications DOI: http://dx.doi.org/10.5772/intechopen.101034*

**Table 2.**

*Parameters of the direct and hydrostatic extrusion.*

**Figure 23.** *Microstructures of magnesium alloys after extrusion with the degree of = 25: a – AZ31, b – AZ61, c – AZ80, d – WE43 λ plastic forming.*


**1.1 Introduction**

There are distinct anatomic and physiologic differences between children and adults that influence not only the etiologies of cardiac arrest but also how we manage these two populations. Children are more at risk for the development of respiratory failure than adults. The discussion of the anatomic reasons behind this is outside the scope of this chapter. Given these anatomic differences between the respiratory systems of adults and children, it is not surprising that the etiology of cardiac arrest in children is usually hypoxia from respiratory failure. In contrast, in adults, the etiology of cardiac arrest is usually secondary to cardiac decompensation [1, 2].

The differences in chest wall compliance between children and adults can also affect their responses to closed chest compressions during CPR. Proposed mechanisms of blood flow during closed chest CPR include compression of the heart between the sternum and spine as well as chest compression (CC)-induced increases in intrathoracic pressure, resulting in pressure gradients from the right heart to the pulmonary vasculature to the left heart and into the systemic vasculature. Based on

these mechanisms, it is thought that better chest wall compliance leads to better cardiac output during CPR. This may explain why infants have better outcomes from cardiac arrest after in-hospital cardiac arrest (IHCA) than older children [1]. There are also differences in their myocardial function. Younger children have a limited ability to increase their stroke volume in the face of demand compared to older children and adults and thus are more dependent on heart rate to maintain cardiac output. For these reasons, in the setting of bradycardia with poor perfusion in children, it is imperative to start CPR. In fact, Nadkarni et al. published a multicenter analysis of IHCA from the National Registry of Cardiopulmonary Resuscitation in 2006 and showed that the incidence of initial rhythm of bradycardia with poor perfusion was significantly higher in children than adults. Children receiving CPR for bradycardia who maintain pulses have much higher rates of survival to hospital discharge (SHD) than those who had pulseless cardiac arrest [2].

The AHA guidelines for CPR in children were last updated in 2015. This book chapter section will cover the most recent recommendations, the basis behind these recommendations, and the research that has accrued since the 2015 guidelines (as summarized in **Table 1**). Approximately 15,000 hospitalized children each year undergo CPR with outcomes improving over time [3]. An analysis of over 7000 pediatric pulseless IHCA events between 2000 and 2018 in the Get With the Guidelines-Resuscitation (GWTG-R) registry showed a 19% absolute increase in SHD over time [3]. Unfortunately, the etiology of these improved outcomes has yet to be elucidated. There are many factors that may have led to the increase in SHD in pediatric IHCA over time. One of the factors that may contribute to improved outcomes is improved CPR quality. The AHA guidelines focus on delivering five components of high- quality CPR, which are delivery of chest compressions of adequate rate and depth, ensuring full recoil between compressions, minimizing interruptions in chest compressions, and avoiding excessive ventilation [4]. Despite these guidelines, there have been multiple studies showing difficulty in achieving these targets during CPR. A single center prospective observational study sought to compare CPR quality before and after the institution of the 2010 AHA guidelines. The authors found that while there was an increase in CC depth, rate, and chest compression fraction (CCF) after the 2010 guidelines, it was difficult to achieve the target goals for rate and depth [5]. In 2018, the Pediatric Resuscitation Quality (pediRES-Q) Collaborative, a large multicenter international pediatric resuscitation quality improvement network, published a landscape study characterizing CPR metrics for children with IHCA. They analyzed 112 events and found that guideline compliance for rate and depth in children is poor, with the most difficulty achieving compliance in younger children [6].

There has been a shift from the "provider"-centric to a "patient"-centric approach to CPR. Instead of targeting a standard depth, rate, and ventilation rate (provider centric), the "patient"-centric approach involves incorporating physiologic monitoring and adjusting CPR to the patient's hemodynamic responses as assessed by more invasive monitors like arterial blood pressure and end tidal carbon dioxide (ETCO2) level. This hemodynamic-directed CPR approach could explain the poor compliance with AHA guidelines (which are "provider" centric) that has been described in the literature.

insufficient data in children for a systematic review for CC rate, and therefore the recommendations are based on evidence for adults. Given simplicity in CPR training and insufficient pediatric evidence, the recommendation was that it is reasonable to use the adult basic life support (BLS) CC rate of 100–120 for children [4]. Since the 2015 update was published, there has been one pediatric study published on this subject. The Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network (CPCCRN) is a network of seven pediatric ICUs that conducts investigations related to pediatric critical care practice. Between 2013 and 2016, the CPCCRN conducted the Pediatric Intensive Care Unit Quality of CPR (PICqCPR) study, a multicenter prospective observational study to evaluate the association between invasive arterial blood pressures during CPR and outcomes. Using the dataset, the primary aim of the study was to evaluate the association between CC rates and blood pressure and survival outcomes. The results of the study showed that when compared to

*AHA recommendations for various CPR quality markers in children vs. adults as well as the recent literature*

**AHA adult recommendations**

Rate 100–120 beats/min 100–120 beats/min 80–100 beats/min

Pauses No more than 10 s No more than 10 s No literature associated with

CCF At least 60% At least 60% No literature associated with

30:2

Duty cycle 50% 50% No association between duty

No advanced airway: chest compression to ventilation ratio

Advanced airway: 10 breaths/min

**Most recent literature since AHA recommendations are**

Higher rates (≥30 breaths/min in children <1 year old and ≥25 breaths/min in older children) associated with improved outcomes compared to lower

**released**

>5 cm but <6 cm No association between depth and outcomes

outcomes

outcomes

rates

≥20 mm Hg No association between ETCO2 and outcomes

≥25 mm Hg DBP ≥ 25 mm Hg in infants

≥20 mm Hg No new evidence

cycle and outcomes

and DBP ≥ 30 mm Hg in children was associated with improved outcomes

**CPR quality marker**

*Pediatric Cardiac Arrest*

Metric

Chest recoil

Arterial blood pressure

Coronary perfusion pressure

*since guidelines are released.*

**Table 1.**

**27**

Physiologic markers

**AHA pediatric recommendations**

*DOI: http://dx.doi.org/10.5772/intechopen.92381*

Depth 1/3 AP diameter of the chest or

<6 cm in adolescents

Ventilation No advanced airway: chest

ETCO2 Reasonable to monitor, but no goals established

goals established

recommendation

Reasonable to monitor, but no

Insufficient evidence to make a

15:2

about 4 cm in infants, >5 cm in children >1 year, and >5 cm but

compression to ventilation ratio

Advanced airway: 10 breaths/min

Full Full

#### *1.1.1 Chest compression metrics*

#### *<IP_ADDRESS> Chest compression rate*

The 2015 update to the AHA guidelines continues to recommend a chest compression rate of 100–120/min. As stated in the 2015 evidence summary, there is

**CPR quality marker AHA pediatric recommendations AHA adult recommendations Most recent literature since AHA recommendations are released** Metric Rate 100–120 beats/min 100–120 beats/min 80–100 beats/min Depth 1/3 AP diameter of the chest or about 4 cm in infants, >5 cm in children >1 year, and >5 cm but <6 cm in adolescents >5 cm but <6 cm No association between depth and outcomes Pauses No more than 10 s No more than 10 s No literature associated with outcomes CCF At least 60% At least 60% No literature associated with outcomes Ventilation No advanced airway: chest compression to ventilation ratio 15:2 Advanced airway: 10 breaths/min No advanced airway: chest compression to ventilation ratio 30:2 Advanced airway: 10 breaths/min Higher rates (≥30 breaths/min in children <1 year old and ≥25 breaths/min in older children) associated with improved outcomes compared to lower rates Duty cycle 50% 50% No association between duty cycle and outcomes Chest recoil Full Full Physiologic markers ETCO2 Reasonable to monitor, but no goals established ≥20 mm Hg No association between ETCO2 and outcomes Arterial blood pressure Reasonable to monitor, but no goals established ≥25 mm Hg DBP ≥ 25 mm Hg in infants and DBP ≥ 30 mm Hg in children was associated with improved outcomes Coronary perfusion pressure Insufficient evidence to make a recommendation ≥20 mm Hg No new evidence

#### *Pediatric Cardiac Arrest DOI: http://dx.doi.org/10.5772/intechopen.92381*

these mechanisms, it is thought that better chest wall compliance leads to better cardiac output during CPR. This may explain why infants have better outcomes from cardiac arrest after in-hospital cardiac arrest (IHCA) than older children [1]. There are also differences in their myocardial function. Younger children have a limited ability to increase their stroke volume in the face of demand compared to older children and adults and thus are more dependent on heart rate to maintain cardiac output. For these reasons, in the setting of bradycardia with poor perfusion in children, it is imperative to start CPR. In fact, Nadkarni et al. published a multicenter analysis of IHCA from the National Registry of Cardiopulmonary Resuscitation in 2006 and showed that the incidence of initial rhythm of bradycardia with poor perfusion was significantly higher in children than adults. Children receiving CPR for bradycardia who maintain pulses have much higher rates of survival to hospital

The AHA guidelines for CPR in children were last updated in 2015. This book chapter section will cover the most recent recommendations, the basis behind these recommendations, and the research that has accrued since the 2015 guidelines (as summarized in **Table 1**). Approximately 15,000 hospitalized children each year undergo CPR with outcomes improving over time [3]. An analysis of over 7000 pediatric pulseless IHCA events between 2000 and 2018 in the Get With the Guidelines-Resuscitation (GWTG-R) registry showed a 19% absolute increase in SHD over time [3]. Unfortunately, the etiology of these improved outcomes has yet to be elucidated. There are many factors that may have led to the increase in SHD in pediatric IHCA over time. One of the factors that may contribute to improved outcomes is improved CPR quality. The AHA guidelines focus on delivering five components of high- quality CPR, which are delivery of chest compressions of adequate rate and depth, ensuring full recoil between compressions, minimizing interruptions in chest compressions, and avoiding excessive ventilation [4]. Despite these guidelines, there have been multiple studies showing difficulty in achieving these targets during CPR. A single center prospective observational study sought to compare CPR quality before and after the institution of the 2010 AHA guidelines. The authors found that while there was an increase in CC depth, rate, and chest compression fraction (CCF) after the 2010 guidelines, it was difficult to achieve the target goals for rate and depth [5]. In 2018, the Pediatric Resuscitation Quality (pediRES-Q) Collaborative, a large multicenter international pediatric resuscitation quality improvement network, published a landscape study characterizing CPR metrics for children with IHCA. They analyzed 112 events and found that guideline compliance for rate and depth in children is poor, with the most difficulty achieving

There has been a shift from the "provider"-centric to a "patient"-centric approach to CPR. Instead of targeting a standard depth, rate, and ventilation rate (provider centric), the "patient"-centric approach involves incorporating physiologic monitoring and adjusting CPR to the patient's hemodynamic responses as assessed by more invasive monitors like arterial blood pressure and end tidal carbon dioxide (ETCO2) level. This hemodynamic-directed CPR approach could explain the poor compliance with AHA guidelines (which are "provider" centric) that has

The 2015 update to the AHA guidelines continues to recommend a chest compression rate of 100–120/min. As stated in the 2015 evidence summary, there is

discharge (SHD) than those who had pulseless cardiac arrest [2].

*Sudden Cardiac Death*

compliance in younger children [6].

been described in the literature.

*1.1.1 Chest compression metrics*

*<IP_ADDRESS> Chest compression rate*

**26**

#### **Table 1.**

*AHA recommendations for various CPR quality markers in children vs. adults as well as the recent literature since guidelines are released.*

insufficient data in children for a systematic review for CC rate, and therefore the recommendations are based on evidence for adults. Given simplicity in CPR training and insufficient pediatric evidence, the recommendation was that it is reasonable to use the adult basic life support (BLS) CC rate of 100–120 for children [4]. Since the 2015 update was published, there has been one pediatric study published on this subject. The Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network (CPCCRN) is a network of seven pediatric ICUs that conducts investigations related to pediatric critical care practice. Between 2013 and 2016, the CPCCRN conducted the Pediatric Intensive Care Unit Quality of CPR (PICqCPR) study, a multicenter prospective observational study to evaluate the association between invasive arterial blood pressures during CPR and outcomes. Using the dataset, the primary aim of the study was to evaluate the association between CC rates and blood pressure and survival outcomes. The results of the study showed that when compared to

AHA guidelines of 100 to <120, higher rate categories were associated with lower systolic (SBP); however, there was no correlation to survival. Also when compared to the AHA guidelines of 100 to <120, a CC rate of 80 to <100 was associated with a higher rate of SHD and survival with favorable neurological outcome (FNO) compared to CC rates within guidelines [7].

date evaluating the association between CC interruptions and outcomes. In 2019, a single-center observational study was published that sought to evaluate the hemodynamic consequences of interruptions in CC. Thirty-two IHCA events were analyzed. The median duration of pauses was brief at 2.4 s; however, BPs before and

For patients without an invasive airway at the time of cardiac arrest, BLS guidelines recommend a compression to ventilation ratio of 15:2 in children if there are two providers (in contrast to 30:2 for adults). Although there is no data to support the optimal compression to ventilation ratio in children, the recommended ventilation rate takes into account a higher baseline respiratory rate in children. For children without advanced airways in place at the time of arrest, there is often an emphasis on tracheal intubation during an IHCA given the most common etiology of IHCA is respiratory failure. The 2019 focused update on PALS reaffirms the 2010 recommendation that during a pediatric OHCA, the use of bag mask ventilation (BMV) is reasonable compared to an advanced airway. The update also specifies that no recommendation for or against an advanced airway could be made. These recommendations were made based on the review of 14 studies of airway interven-

In contrast to the recommendation for a higher ventilation rate without an advanced airway, when an advanced airway is in place, AHA guidelines recommend that ventilation rates of 10 breaths/min be applied to all age groups during CPR in order to simplify training. During CPR, cardiac output is usually about 25% of normal, and thus lower ventilation rates are recommended to match the lower output state, given the detrimental effects of positive pressure ventilation on venous return and right heart afterload. However, the etiology of cardiac arrest in children is usually asphyxia in nature compared to the primary cardiac origin of most adult cardiac arrests, and thus the recommendations of equal ventilation rates in children as to adults have been questioned. In 2019, the CCPCRN published the only study to date that has analyzed the association of ventilation rates in pediatric cardiac arrests and survival outcomes. As part of the PICqCPR study, the authors analyzed 52 events in patients with an invasive airway in place at the time of the cardiac arrest. No events were within the guideline ventilation rate (defined as 10 2 breaths/min), and more than half of the events were considered high ventilation rates (defined as > or equal to 30 breath/min in infants <1 year and > or equal to 25 in children >1 year). In fact, higher ventilation rates were associated

The term "duty cycle" refers to the amount of time spent in the compression phase of CPR. AHA guidelines for adult cardiac arrest recommend a duty cycle of 50% [20]. There have been no pediatric recommendations since 2005 on duty cycle. The only pediatric study to date on duty cycle was published in 2016. It was a single-center observational study that analyzed 97 pediatric events and found no

AHA guidelines recommend full chest recoil in between compressions, to avoid leaning. In 2009, a single-center prospective observational study sought to evaluate

after the pauses did not differ significantly [17].

*DOI: http://dx.doi.org/10.5772/intechopen.92381*

tions in children who had cardiac arrests [18].

with higher odds of SHD [19].

association with duty cycle and survival [21].

*<IP_ADDRESS> Duty cycle*

*<IP_ADDRESS> Chest recoil*

**29**

*<IP_ADDRESS> Ventilation*

*Pediatric Cardiac Arrest*

### *<IP_ADDRESS> Chest compression depth*

The 2015 update to AHA guidelines recommend to compress at least 1/3 of the anterior–posterior (AP) diameter of the chest, which is about 4 cm in infants, 5 cm in children, and greater than 5 cm but no more than 6 cm in adolescents [4]. Two single-center pediatric studies were reviewed for the 2015 update to the AHA guidelines. The first study was a case series of six infants after cardiac surgery who had CPR. In those infants, aged 0–7 months, attempting to compress the chest to ½ the AP diameter increased the SBP significantly compared to attempts to compress the chest to 1/3 the AP diameter [8]. The second study looked at 87 chest compression events in children >1 year and showed that AHA compliant guideline CC depths >51 mm were associated with improved 24-h survival compared to more shallow CC depths [9]. Since the 2015 update, there has been only one study published. This was a multicenter prospective observational study that looked at out-of-hospital cardiac arrests (OHCA). They looked at 153 pediatric events (children 1–19 years of age) with CPR metric data and found that there was no association with CC depth and return of spontaneous circulation (ROSC) [10].

#### *<IP_ADDRESS> Minimizing interruptions in chest compressions*

The 2015 AHA guidelines continue to emphasize minimizing interruptions in chest compressions, in particular to less than 10 s. Ideally, these pauses should be coordinated so that a pulse check, rhythm check, and compressor switch occur at the same time and should only occur every 2 min. There should be a person assigned to the role of the pulse check, positioned with his/her finger on the pulse before the pause to minimize the pause duration. Chest compression fraction is defined as the time spent doing chest compressions during CPR. The 2013 AHA consensus statement on CPR quality recommended a CCF of at least 80% [11]; however, the 2015 AHA BLS guidelines recommend a CCF of at least 60% [12]. Observational studies of cardiac arrests often show that pauses can be more prolonged and more frequent than expected. In a single-center observational study in a pediatric emergency room, 33 cardiac arrests were analyzed. While the majority of pauses were <10 s in duration, 33% of pauses were >10 s. The number of coordinated pauses were rare, only 7% of the time [13]. A more recent observational study of CPR quality in two pediatric emergency departments analyzed 81 cardiac arrests. While median CCF was 91% with a median pause duration of 4 s, 22% of pauses were prolonged (>10 s). Again, the number of coordinated pauses were rare (6%) and prolonged with a median of 19 s [14]. Although the AHA guidelines recommend to switch providers performing CC every 2 min to prevent rescuer fatigue and therefore inadequate CPR quality, they also acknowledge that when a CPR feedback device is used, some individuals can go longer than 2 min [15]. A single-center observational study that sought to characterize causes for interruptions found that provider switch accounted for the majority of pauses. Individuals performing CC for at least 120 s compared to those switching earlier had less leaning, increased CC depth, and better compliance for depth with AHA guidelines [16]. While there is limited evidence in adults to support these guidelines on duration of pauses and CCF, these recommendations have been applied to children. There are no pediatric studies to

#### *Pediatric Cardiac Arrest DOI: http://dx.doi.org/10.5772/intechopen.92381*

date evaluating the association between CC interruptions and outcomes. In 2019, a single-center observational study was published that sought to evaluate the hemodynamic consequences of interruptions in CC. Thirty-two IHCA events were analyzed. The median duration of pauses was brief at 2.4 s; however, BPs before and after the pauses did not differ significantly [17].