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Out-of-hospital circulatory arrest: factors determining the outcome Amsterdam resuscitationstudy (ARREST) 2 and 3

Waalewijn, R.A.

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Citation for published version (APA):Waalewijn, R. A. (2002). Out-of-hospital circulatory arrest: factors determining the outcome Amsterdamresuscitation study (ARREST) 2 and 3.

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Download date: 25 Jun 2020

Chapte rr 6 Advancedd cardiopulmonary resuscitation performance after

out-of-Hospitall cardiac arrest: Does it improve survival?

Reinierr A. Waalewijn MD", Jan C.P. Tijssen PhD3, Rien de Vos, PhDb, Rudolphh W. Koster MD, PhDa

Departmentt of Cardiology, b Clinical Epidemiology & Biostatistics, Academic Medical Center, Universityy of Amsterdam, The Netherlands.

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Abstrac t t

Thiss study analyzed the influence on survival of the last two links of the chain of survival: early defibrillationn and early Advanced Life Support (ALS). Included were all witnessed arrests where EMSS personnel attempted resuscitation from the ARREST database. Defibrillation, ALS interventions,, and time intervals were analyzed in relation to survival. From the 1087 included patients,, 144 (13%) survived to discharge. Eighty-three patients did not require ALS procedures too restore spontaneous circulation (ROSC), resulting in a high survival rate (84%). When delay to defibrillationn increased the chance to survive declined rapidly, especially when no bystander performedd basic life support. The chance to achieve ROSC occurred mainly after the first three defibrillatoryy shocks. When ALS was needed extended, delay resulted in a decreased survival for patientss with and without a shockable initial rhythm. We found that ALS procedures had beneficiall effect compared to patients where EMS personnel could not achieve ALS treatment. Afterr defibrillation, endotracheal intubation is the most important treatment of any circulatory arrest.. Although ROSC was still achieved after 90 minutes of ALS measures, survival diminished too nihil after 25 minutes. It is difficult to proof that ALS is a necessary treatment during resuscitationn since the results were confounded by indication bias. To measure the effect of ALS onee should consider the need for ALS and the time to the start of ALS performance. When ALS is needed,, its delay leads to a markedly reduced and not performing ALS was associated with the worstt survival. Prolonging ALS measures over 25 minutes seemed of limited value for out-of-hospitall adult cardiac arrests. Early ALS remains a valuable link in the chain of survival.

1.. Introductio n

Defibrillationn and Advanced Life Support (ALS) considered two separate links in the Chain of Survival.11 Defibrillation has proved to be the most important life-saving procedure for patients withh a shockable initial heart rhythm.2 ' But other ALS measures never proved to be a survival improvingg treatment.4 Nevertheless, it is considered an essential part of resuscitation. One study reportedd a survival of 2% of patients with ventricular fibrillation treated by ambulance personnel whoo were trained to perform basic life support (BLS) and to defibrillate only.5 This suggests that thee contribution of ALS procedures might improve survival.

Thee objective of this study was to separately analyze the effect of defibrillation and ALS proceduress on survival, for patients with and without a shockable initial rhythm.

2.. Patient s and Method s

2.7.. Study design Forr this analysis we used patients from the database of the Amsterdam Resuscitation Study.

Thee design of this study is published earlier in detail.6 In brief, the database provided information aboutt all consecutive out-of-hospital cardiac arrests between June 1, 1995 and August 1, 1997. Speciallyy trained research personnel at the scene ensured an accurate registry according to the Utsteinn recommendation.7 For this analysis we selected patients with a witnessed arrest and in whomm EMS personnel attempted resuscitation. All required ethics committees approved the study. .

Thee study was executed in Amsterdam and its surrounding areas, populated by 1.3 million peoplee and served by a single tiered emergency medical service (EMS) system. One central dispatchh center dispatch seven ambulance services. In case of a resuscitation attempt always two ambulancess are directed to the scene. All ambulances are staffed with a paramedic and a driver qualifyy to perform defibrillation and ALS activities, which include endotracheal intubation,

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intravenouss administration of medication, according to a national protocol based on the ERC guideline.8 8

2.2.2.2. Definitions AA cardiac arrest was when a victim was unconscious and pulseless confirmed by EMS

personnel.. An unnatural cause of the arrest was trauma, drowning, suicide or intoxication. Shockablee rhythms were initial rhythms (ventricular fibrillation or pulseless ventricular tachycardia)) treated with a defibrillatory shock by EMS personnel. Unless specially stated, all time intervalss are measured from the moment of collapse. The time to call was the interval to the momentt the call entered the dispatch center. The time to EMS arrival at the patient's side was thee interval to the power-on of the defibrillator. Time to shock was the interval to the first defibrillatoryy shock. ALS interventions were endotracheal intubation and intravenous drug administration.. Time to ALS was the interval to the first ALS intervention. 'ALS not needed' were casess where a spontaneous circulation returned before ALS efforts were initiated. 'ALS not performed'' were those cases where ALS interventions were attempted by EMS personnel, but couldd not be accomplished. Duration of ALS measures was defined as start of ALS to the time of definitivee ROSC. Definitive ROSC was not discontinued by re-arrest until hospital admission. Endpointss of this study were return of spontaneous circulation (ROSC) and survival, defined as dischargedd alive from the hospital.

13-144 15-16 17-18 19-20 >20

Timee to first defibrillatory shock (min)

FigureFigure 1. The histogram demonstrates survival in relation to the time interval from collapse to the first defibrillatorydefibrillatory shock for patients with and without BLS before arrival of EMS personnel. Survival declineddeclined rapidly when the delay to the first defibrillatory shock increased, especially when no bystanderbystander started BLS before defibrillation. There were no patients with BLS when the first defibrillatorydefibrillatory shock was delivered within 2 minutes.

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2.3.2.3. Statistical methods Thee relation to the number of defibrillatory shocks and ROSC was calculated in cumulative

proportions.. All ALS interventions and ALS delays categorized in time intervals of four minutes weree related to survival and expressed as odds ratios (OR) with 95% confidence interval (CI). The relationn of duration of ALS measures on ROSC and on survival was calculated in cumulative proportions. .

3.. Result s

3.7.. Study population Forr this analysis we included 1087 witnessed circulatory arrests. In 47 cases there was an

unnaturall cause. Ten patients with a natural cause were younger than 18 years. The mean age of thee patients was 63 years (range: 0-96), 813 (75%) were men. In 167 (15%) cases EMS personnel weree present the moment the patient collapsed, from the remaining 920 patients 490 (53%) receivedd BLS prior to the arrival of the EMS. Of the included patients, 578 (53%) had a shockablee initial rhythm and 509 (47%) had a nonshockable initial rhythm.

3.2.3.2. Defibrillation, delay and outcome Forr 578 patients with a shockable initial rhythm survival declined rapidly, when the time to

thee first defibrillatory shock increased (Figure 1). This effect was even more pronounced when no bystanderr performed BLS before defibrillation.

Inn 284 patients (49%) with a shockable initial rhythm, return of spontaneous circulation (ROSC)) was achieved after defibrillation. It took at least three shocks, including shocks for refibrillationn to achieve ROSC in 189 patients, 67% of all patients that eventually had ROSC (Figuree 2). The chance of ROSC diminished rapidly when the number of defibrillatory shocks increased.. Only nine patients (3%) needed more than 9 shocks to achieve ROSC.

Cumulativee proportion ROSC

100--

9 0 --

800 -

70 0

60 0

50 0

40 0

11 2 3 4 5 6 7 99 1011 12 13 14 15 16 1718 1920 2122 23 24 25

Numberr of defibrillatory shocks

FigureFigure 2. The histogram presents the cumulative proportion of patients where spontaneous circulation waswas restored (ROSC) in relation to the increased number of defibrillatory shocks. There is a rapid decreasedecrease in the chance to achieve ROSC when the number of defibrillatory shocks raised and became almostalmost nihil after 9 shocks. Re-arrest could occur, so ROSC was no guarantee for survival.

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3.3.3.3. Shockable initial rhythm: ALS procedure and outcome Fromm the 578 patients with a shockable initial rhythm, 76 (13%) patients did not require ALS

measuress in order to achieve ROSC (Table 1). Twenty-one percent (121/578) of patients with a shockablee initial rhythm survived to hospital discharge. More than half (65/121) of the survivors didd not need ALS interventions. From those who needed ALS, the longer the delay to the start of ALSS the lower the survival. Delays over 20 minutes resulted in a minimal survival (2%), comparablee to the situation when ALS was not performed. Patients in where no ALS activities weree performed had the lowest survival chance and those who were only intubated besides defibrillationn had the best change to survive. Furthermore when ALS was needed, any kind of drugg regimes was related to a worse survival compared to no i.v. drugs administrated.

3.4.3.4. Nonshockable initial rhythm: ALS procedures and outcome Fromm the 509 patients with nonshockable rhythm, 7 did not need ALS efforts to achieve

ROSC.. When ALS was needed, delays of longer than 8 minutes resulted in a minimal survival rate.. Concerning the ALS activities, those who were only intubated had the best change to survive.. No i.v. drug was related to a better survival than any other drug regimes, although not all differencess reached the level of statistical significance.

3.5.3.5. All initial rhythm: outcome and duration of ALS Fromm all 966 patients where ALS was performed, in 352 (36%) patients ALS efforts resulted in

ROSCC and 74 (8%) of these patients survived to hospital discharge. There was still a chance to achievee ROSC after 90 minutes of ALS (Figure 3). Survival was minimal after 25 minutes of ALS measures.. One patient survived after 55 minutes of ALS procedures.

Cumulativee proportion

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Patientss survived to discharge

i i ii i i i i i i i

00 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Durationn of ALS in minutes

FigureFigure 3. The graphic presents the cumulative proportion of patients where spontaneous circulationcirculation was restored (ROSC) and of patients who survived to hospital discharge in relation toto the duration of Advanced Life Support (ALS) in minutes. The chance to achieve ROSC is possiblepossible after even 90 minutes of ALS. When ALS measures took over 25 minutes, survival to hospitalhospital discharge diminished.

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4.. Discussio n

Thiss observational study focussed on the last two links of the chain of survival: defibrillation andd ALS. Survival decreased rapidly when time to defibrillation increased, especially when no BLSS was performed. The vast majority of ROSC occurred after the first three defibrillatory shocks. Eighty-threee patients did not need ALS procedures to restore spontaneous circulation, and these patientss had the best chance to survive. When ALS was needed delay in the ALS procedures resultedd in a decreased survival. Patients where no ALS was needed, but not was performed by EMSS personnel had the worse chance of survival.

Shorteningg the delay to the first defibrillatory shock remains the most effective improvement off the emergency medical system for patients with a shockable initial rhythm as was described earlier.99 Also, performing BLS before arrival of EMS personnel positively affected survival for patientss with a shockable initial rhythm. This study support the conclusions that BLS not only keepss the patient in VF,10 but also improves survival of patients found in VF when treated with a defibrillatoryy shock.1112

Althoughh ALS is described as an essential link in the chain of survival, the additional benefit off ALS is questioned.413 The lack of any proven benefit of ALS activities is probably due to indicationn bias. The longer the duration of the resuscitation efforts, the more ALS interventions willl be indicated and f.i. the more drugs will be administered. Our study demonstrated that in 833 cases ALS procedures not were even needed to restore circulation, as was also described earlier.144 For the other patients we found a beneficial effect of early performed ALS, regardless of thee initially recorded rhythm. However, the amount of survivors with nonshockable rhythm was veryy small and no clear trend in time could be proven. We also found that ALS measures were indeedd beneficial compared to patients where EMS personnel should, but could not perform ALS.. It seems that after defibrillation, endotracheal intubation is the most important treatment of anyy circulatory arrest.

Wee found a high survival rate in the group of patients with a nonshockable initial rhythm that didd not need ALS. The possible explanation for this finding is that there was probably no circulatoryy arrest, although EMS personnel did not detected a pulse. It is known from studies that evenn for professionals, conformation of a cardiac arrest by checking the carotid pulse could be difficult.15 5

Bonninn et al. suggested in a previous study to terminated out-of-hospita! resuscitation efforts afterr 25 minutes of ALS without recovery of ROSC, excluding hypothermic patients or persistent VF.166 In, our study we found that survival was very little after 25 minutes, but still three patients leftt the hospital alive after AL5 of longer duration.

LimitationLimitation of the study

Becausee we performed an observational study we could not control for the indication bias. Althoughh we considered the different initial heart rhythms as the most important predictors for survival,, many other differences could have biased our findings. For example, we did not take intoo account the experience of the ambulance crew, as was suggested by Soo et al.17

Conclusion Conclusion

Wee conclude that ALS is not always needed, resulting in the best chance to survive. When ALSS is needed, benefit from ALS performance was most when administrated early. When analyzingg the effect of ALS two findings must be taken into account: the need for ALS and the delayy to ALS procedures. Prolonging ALS measures over 25 minutes seemed of limited value for out-of-hospitall adult cardiac arrests. Early ALS remains a valuable link in the chain of survival.

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Acknowledgement s s Wee want to thank the research personnel: I. Tulevski, P.S. Visser, D. Dalhuisen, B.P.W. de

Gouw,, E.J.P. Vlieger, M. Akarriou, F.R. Banga, L.A.M. Verkouteren, J.M. Immink, and S. Ritmeesterr who took part in the data collection and offered their day and night rest for this project.. We also thank the personnel of the dispatch center: CPA Amsterdam, the ambulance services:: GG&CD Amsterdam, VZA Amsterdam, GGD Amstelveen, GGD Zaanstad, GGD Hoofddorp,, Ruis Purmerend, Boon Wormerveer, the police districts: Amsterdam/Amsteliand, Zaanstreek/Waterland,, Haarlemmermeer, the hospitals: Boven-Y ziekenhuis, de Heel ziekenhuis,, St. Lucas/Andreas ziekenhuis, Slotervaartziekenhuis, Onze Lieve Vrouwe Gasthuis, Academischh Ziekenhuis Vrije Universiteit, Waterlandziekenhuis, Ziekenhuis Amstelveen, Kennemerr Gasthuis, Spaarne ziekenhuis, Academisch Medisch Centrum and all general practitionerss who were willing to give medical information about the patients included in this study. .

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