Cardiac arrest during anesthesia at a tertiary teaching hospital: prospective survey from 1996 to 2002

Abstracts

JUSTIFICATIVA E OBJETIVOS: A incidência e causas de parada cardíaca (PC) durante a anestesia variam e são difíceis de comparar diante dos diversos métodos usados nos estudos. A pesquisa teve como objetivo estudar todas as PC ocorridas no intra e pós-operatório, durante um período de sete anos, de 1996 a 2002, em hospital de ensino de atendimento terciário para determinar incidência e causas da PC. MÉTODO: A incidência prospectiva de PC ocorrida durante a anestesia em 40.941 pacientes consecutivos foi identificada, utilizando-se um Banco de Dados. Todos os casos de PC e óbito foram revisados por uma Comissão, para determinar o fator desencadeante da PC ou óbito. A incidência de PC foi calculada em relação à idade, sexo, estado físico, segundo a classificação da ASA, tipo de atendimento, fatores desencadeantes, como alteração do estado físico do paciente e complicações cirúrgicas e anestésicas, tipo de anestesia e evolução para óbito. RESULTADOS: Ocorreram 138 PC (33,7:10.000), sendo a maioria em recém-nascidos, crianças até um ano e idosos, no sexo masculino (65,2%), em pacientes com estado físico ASA III ou superior, em atendimento de emergência e durante anestesia geral. Alterações do estado físico foram o principal fator de PC (23,9:10.000), seguidas de complicações cirúrgicas isoladamente (4,64:10.000) ou associadas a alterações do estado físico (2,44:10.000) e da anestesia isoladamente (1,71:10.000) ou associadas a alterações do estado físico (0,98:10.000). O risco de óbito relacionado à anestesia como fator principal ou contributivo foi igual para ambos (0,49:10.000). As principais causas da mortalidade associada à anestesia foram os problemas ventilatórios (45,4%), eventos relacionados à medicação empregada (27,3%), aspiração pulmonar (18,2%) e hidratação excessiva (9,1%). CONCLUSÕES: A incidência de PC durante a anestesia ainda continua elevada. A maioria das PC e óbitos associados à anestesia foi relacionada ao manuseio das vias aéreas e à administração de medicamentos e anestésicos.

COMPLICAÇÕES; COMPLICAÇÕES; TÉCNICAS ANESTÉSICAS; TÉCNICAS ANESTÉSICAS; TÉCNICAS ANESTÉSICAS; TÉCNICAS ANESTÉSICAS

SCIENTIFIC ARTICLE

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002^*

Incidencia de parada cardíaca durante anestesia, en hospital universitario de servicio terciario. Estudio prospectivo entre 1996 y 2002

Leandro Gobbo Braz, M.D.^I_; José Reinaldo Cerqueira Braz, TSA, M.D. ^II; Norma Sueli Pinheiro Módolo, TSA, M.D.^III; Paulo do Nascimento Júnior, TSA, M.D.^III; Ana Paula Shuhama, M.D.^IV; Laís Helena Camacho Navarro M.D.^I

^IEx-ME₂ do CET/SBA do Departamento de Anestesiologia da FMB UNESP e atual Pós-Graduando do Curso de Mestrado do Programa de Pós-Graduação em Anestesiologia da FMB, UNESP. Bolsista do CNPq

^IIProfessor Titular do CET/SBA do FMB UNESP

^IIIProfessora Adjunta e Livre-Docente do CET/SBA da FMB UNESP

^IVGraduanda (6º ano) da FMB UNESP. Bolsa de Iniciação Científica PIBIC/CNPq

^{Correspondence}

SUMMARY

BACKGROUND AND OBJECTIVES: Cardiac arrest (CA) incidence and causes during anesthesia are variable and difficult to be compared due design variations of major studies. This survey aimed at evaluating all intra and postoperative CA from 1996 to 2002 at a tertiary teaching hospital to determine CA incidence and causes.

METHODS: The prospective incidence of CA during 40,941 anesthesias was identified from a database. All CA and deaths were reviewed by a Committee in order to determine triggering factors. CA cases were studied as to age, gender, ASA physical status, type of treatment, triggering factors, such as changes in patients physical status and surgical and anesthetic complications, type of anesthesia and evolution to death.

RESULTS: There were 138 CA (33.7:10,000), being most of them neonates, children aged less than 1 year, elderly people, males (65.2%), physical status ASA III or poorer, in emergency surgeries and during general anesthesia. Physical status changes were the major CA factor (23.9:10,000) followed by surgical complications alone (4.64:10,000) or associated to physical status changes (2.44:10,000) and anesthetic complications alone (1.71:10,000) or associated to physical status changes (0.98:10,000). The risk of anesthesia-related death as major or contributing factor was similar for both (0.49:10,000). Major anesthesia-related death causes were ventilatory problems (45.4%), drug-related events (27.3%), pulmonary aspiration (18.2%) and fluid overload (9.1%).

CONCLUSIONS: CA incidence during anesthesia is still high. Most anesthesia-related cardiac arrests and deaths were related to airway management and drug and anesthetic administration.

Key Words: COMPLICATIONS: cardiac arrest, death; ANESTHETIC TECHNIQUES, General: epidural, Regional, spinal block

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: La incidencia y causas de parada cardíaca (PC) durante la anestesia varían y son difíciles de comparar delante de los diversos métodos usados en los estudios. El objetivo de la pesquisa fue de como estudiar todas las PC ocurridas en el intra y pos-operatorio, durante un período de siete años, de 1996 a 2002, en un hospital de enseñanza de servicio terciario para determinar incidencia y causas de la PC.

MÉTODO: La incidencia prospectiva de PC ocurrida durante la anestesia en 40.941 pacientes consecutivos fue identificada, utilizándose un Banco de datos. Todos los casos de PC y fallecimiento fueron revisados por una Comisión, para determinar el factor desencadenante de la PC o fallecimiento. La incidencia de la PC fue calculada con relación a la edad, sexo, estado físico, según la clasificación de la ASA, tipo de servicio, factores desencadenantes, como alteración del estado físico del paciente y complicaciones quirúrgicas y anestésicas, tipo de anestesia y evolución para fallecimiento.

RESULTADOS: Ocurrieron 138 PC (33,7:10.000), siendo la mayoría en recién nacidos, niños hasta un año de edad y ancianos, en el sexo masculino (65,2%), en pacientes con estado físico ASA III o superior, en servicio de emergencia y durante anestesia general. Alteraciones del estado físico fueron el principal factor de PC (23,9:10.000), seguidas de complicaciones quirúrgicas aisladamente (4,64:10.000) o asociadas a alteraciones del estado físico (2,44:10.000) y de la anestesia aisladamente (1,71:10.000) o asociadas a alteraciones del estado físico (0,98:10.000). El riesgo de fallecimiento relacionado a la anestesia como factor principal o contributivo fue igual para ambos (0,49:10.000). Las principales causas de la mortalidad asociada a la anestesia fueron los problemas ventilatorios (45,4%), eventos relacionados a la medicación usada (27,3%), aspiración pulmonar (18,2%) e hidratación excesiva (9,1%).

CONCLUSIONES: La incidencia de PC durante la anestesia aún continúa elevada. La mayoría de las PC y fallecimientos asociados a la anestesia fue relacionada al manoseo de las vías aéreas y a la administración de medicamentos y anestésicos.

INTRODUCTION

In spite of major advances in anesthesia and surgery, perioperative morbidity and mortality are still high, although seeming to have decreased, especially as from 1990. So, most epidemiologic studies in the 80s ^1-13 report anesthesia-related mortality between 0.7 and 3.7:10,000 anesthesias, while studies from the 90s and 2000s ^14-24 report incidence between 1 to 2:10,000 anesthesias, with incidences below 1:10,000 in several statistics (Chart I).

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

There are few Brazilian epidemiologic data. Ruiz Neto et al. ¹², in 1986, have published a prospective study on the incidence of cardiac arrest during anesthesia after reviewing 51,422 records of anesthesias induced from 1982 to 1984 at a tertiary teaching hospital. They have reported 205 cardiac arrests, that is, 39:10,000 anesthesias, with 99 deaths (19:10,000). If clearly anesthesia-related deaths are computed, the mortality rate is 1.75:10,000 anesthesias. In more recent retrospective studies involving the same institution, a higher number of cardiac arrests has been found, that is, 49:10,000 anesthesias ¹⁷ and 51:10,000 anesthesias ²³, but lower anesthesia-related mortality rate has been found in 1995 (1:12,963) ¹⁷ and in 1998 and 1999 (1:82,641) ²³.

In our institution ¹⁸, in the period February 1988 to March 1996, there have been 184 cardiac arrests during 58,500 anesthesias, that is, a still high incidence of 13.4:10,000 anesthesias, with 124 deaths (21.7:10,000). If only anesthesia-related deaths are computed, there has been mortality rate of 0.85:10,000 anesthesias.

Studies in other countries indicate that the incidence of cardiac arrest during anesthesia is lower as compared to Brazil (1.1 to 30:10,000) ^{5,9,10,13,20,21,24,25,30,31}.

Considering the importance of an epidemiologic study on the incidence of cardiac arrest during anesthetic-surgical procedures in Brazil to propose preventive measures to increase anesthetic-surgical safety, our survey aimed at evaluating the incidence of cardiac arrest in operating rooms (OR) and post-anesthetic care units (PACU) at a teaching hospital in the period 1996 to 2002.

METHODS

After the Medical Ethics Committee approval, a prospective and descriptive study was performed with 40,941 consecutive patients submitted to anesthetic-surgical procedures at a public tertiary teaching institute (Hospital das Clinicas, Faculdade de Medicina de Botucatu, UNESP) in the period January 1996 to December 2002.

All patients were evaluated by an anesthesiologist immediately before emergency or urgency surgical procedures and the day before routine procedures. Basic safety monitoring in the operating room (OR) during regional anesthesia or epidural and spinal blocks, in addition to sedation, included: ECG, noninvasive blood pressure and pulse oximetry. For general anesthesia, in addition to above-mentioned monitoring, capnography, oxygen and inspired and expired halogenate anesthetics concentration and ventilation parameters were included. Basic PACU monitoring was the same as OR.

The study has evaluated computerized database records from which demographics, gender, anesthesia and surgery-related information and OR and PACU morbidity were extracted. Also part of the evaluation were special records for each cardiac arrest and death, which were filled immediately after the event; evaluation of records of all patients included in the study and of autopsy reports, when performed. If needed, additional information was obtained from the anesthesiologist participating in the procedure. A summary was prepared for each case to be discussed by two to four anesthesiologists of our Department, aiming at determining cardiac arrest or death triggering factor.

Cardiac arrests were calculated based on age, gender, physical status, treatment (routine, urgency or emergency), surgical clinic, place (OR or PACU), triggering factors (changes in physical status, surgical or anesthetic complications), type of anesthesia and OR or PACU discharge conditions (good, regular or poor general status). Factor contributing to death was also evaluated.

To determine major cardiac arrest triggering factor, five categories of causes were adopted: surgery, when CA was a consequence of technical-surgical problems; physical status, in the presence of organic changes decisively contributing to CA; anesthesia, when anesthetic procedure alone was the cause of CA; and associated factors, in the presence of organic changes contributing to CA when added to anesthetic or surgical problems.

Mortality rate was also determined for each triggering factor, such as the relation between the number of deaths caused by the factor and total number of cardiac arrests.

Considering that cardiac arrest and death are uncommon events during anesthesia, their causes were always presented related to 10,000 anesthesias, as internationally adopted.

RESULTS

From 40,941 anesthesias induced in the period April 1996 to December 2002, there were 138 cardiac arrests (33.7:10,000 anesthesias). Most were observed in the OR (14.3:1 as compared to PACU) (Table I), primarily involving neonates, children below 1 year, adults aged 51 to 64 years and elderly patients (Table II); male patients (1.9:1 as compared to females) (Table III), patients with physical status ASA III or poorer (Table IV), in emergency situations (12:1 as compared to routine procedures) (Table V) and during general anesthesia (29.5:1 as compared to spinal and epidural anesthesia (Table VI).

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

The distribution of cardiac arrests according to surgical specialty has shown a higher incidence when patients were operated on by two or more surgical clinics (multiclinics) (6.67%), in cardiac surgeries (3.85%), chest surgeries (1.47%), vascular surgeries (0.71%) and pediatric surgeries (0.56%) (Table VII).

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Changes in patients' physical status were major CA cause, followed, in decreasing order of incidence, by the following triggering factors: surgery, surgery associated to physical status changes, anesthesia alone and anesthesia associated to physical status changes (Figure 1).

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Eleven cardiac arrests were related to anesthesia (2.69:10,000 anesthesias), being 7 exclusively attributed to anesthesia, resulting in an incidence of 1.71:10,000 anesthesias. Anesthesia has contributed to 4 CA, resulting in an incidence of 0.98:10,000 anesthesias (Figure 1).

There were 89 deaths, with the incidence of 21.7:10,000 anesthesias, being most of them related to changes in patients' physical status. Four deaths were attributed to anesthesia (0.98:10,000 anesthesias), being two of them solely attributed to anesthesia (0.49:10,000 anesthesias) and the remaining two had anesthesia as contributing factor (0.49:10,000 anesthesias) (Figure 2).

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

Cardiac arrest mortality having anesthesia as major or contributing factor has been lower (36.4%) as compared to patients' physical status (70.1%) or surgery (58.6%), the latter considered both major and contributing factor.

As to PACU discharge conditions, from 49 patients with cardiac arrest and no death, 63.3% were in poor general status, 26.7% in regular general status, and 10% in good general status. As to discharge conditions of patients with anesthesia-related cardiac arrests, 36.4% were in poor general status and 66.8% were in regular general status.

Causes of cardiac arrest associated or not to death, when anesthesia was the major or associated triggering factor, are summarized in table VIII.

Brazilian Journal of Anesthesiology, 2004; 54: 6: 755-768

Cardiac arrest during anesthesia at a tertiary teaching hospital. Prospective survey from 1996 to 2002

Leandro Gobbo Braz; José Reinaldo Cerqueira Braz; Norma Sueli Pinheiro Módolo; Paulo do Nascimento Júnior;

Ana Paula Shuhama; Laís Helena Camacho Navarro

DISCUSSION

There are in the literature some references on cardiac arrest during anesthesia ^{5,9,10,12,13,20,21,24,26,30,31}, but most are related to the incidence of death during anesthesia ^1-24.

There are major difficulties in comparing different studies due to differences in surgical and anesthetic procedures, to different types of patients and hospitals studied, and to the study period. Some are based on voluntary statements of incidents; others on case series, and few are prospective studies.

A major difference among mortality studies is the definition of anesthetic death. Most studies determine a period of time in which there has been death. Variations in the definition of anesthesia-related mortality may affect the computation of the incidence of the complication, such as the time period considered, which may include PACU stay or be extended to 24 hours or even 30 days after surgery.

In our study, since the definition of anesthesia-related mortality was limited to the peri-anesthetic period and PACU stay, we have evaluated the incidence not only of cardiac arrests but also of deaths, highlighting patients' condition at PACU discharge. It has to be considered that ours has been a prospective study and that these aspects enhance and increase its reliability and importance.

The incidence of cardiac arrest during anesthesia and in the post-anesthetic recovery period was 33.7:10,000 anesthesias. This is a higher incidence as compared to other recent international studies, such as Arbous et al. ¹⁹ who have reported 9:10,000 anesthesias, Biboulet et al. ²⁰, with 2.4:10,000, Newland et al. ²¹, with 19.7:10,000, Kawashima et al. ²⁴, with 7.1:10,000, and Sprung et al. ²⁵ , with 4.3:10,000 anesthesias. However, it is slightly higher than the incidence obtained in a previous survey ¹⁸, which has been 31.4:10,000 anesthesias.

On the other hand, some Brazilian authors have found an even higher incidence of cardiac arrest, from 39 to 51:10,000 anesthetic procedures ^12,17,23. The similarity of these studies and ours is to be stressed, since although performed in different decades, they were developed in tertiary teaching hospitals, with active first aid units and treating a broad range of the population with a high number of urgency and emergency surgeries performed in ASA III to V patients, factors which certainly have contributed to the high incidence of cardiac arrest during anesthesia in theses studies. It should also be considered that these studies have involved cardiac arrest up to 24 postoperative hours.

One feature of this study was to include the experience of a single institution. This might be considered negative since care peculiarities could have influenced data, but there is also the advantage of data consistency, which would be rather difficult with multicenter study data.

Hospital das Clínicas, Universidade Estadual Paulista - UNESP is a reference center for tertiary care, with 400 beds and 6000 surgeries per year, treating an estimated population of 1 million people. It also receives victims of car accidents of a broad highway system. The hospital is also a reference for obstetric patients and high-risk neonates, and for children and patients with surgical heart diseases. Anesthetic care in the hospital is performed by professors, physicians and residents, so the institution is relatively small, with a clinical team for anesthesiologic care that has barely not changed during the study period.

In considering the distribution of cardiac arrest in terms of triggering factors, it has been observed that physical status changes were the major factor, with an incidence of 23.9:10,000, followed by surgery as major or associated cause, with an incidence of 7.08:10,000, and by anesthesia as major or associated cause with 2.69:10,000 (Figure 1). There has been a slightly lower incidence of 20:10,000 as compared to previous survey ¹⁸ due to changes in physical status, similar incidence of 7.9:10,000 for surgery as major or associated cause, and higher incidence of 3.6:10,000 for anesthesia as major or associated cause.

In the study by Ruiz Neto et al. ¹², developed in the 80s, anesthesia was the major cause of cardiac arrest in patients submitted to elective surgeries, with an incidence of 76.5%, followed by surgery with 17.6% and physical status changes with 5.9%. For emergency surgeries, surgical procedure was the first with 59.7%, followed by anesthesia with 22.7% and physical status changes with 17%. So, in comparing these data with our survey, it is observed that in Brazil there has been a major decrease in the number of cardiac arrests associated to anesthesia and surgery, and an increase in those associated to patients' physical status.

So, according to this study and to other studies performed in our country ^12,17,18,23, one may conclude that the incidence of cardiac arrest is not decreasing in Brazil, but its causes have largely changed in the last decades, with decrease, especially as from the 90s, of cardiac arrests of anesthetic and surgical origin, but with major increase in those related to physical status changes. The widespread indication of surgeries for patients with progressive severity and elderly (above 80 years), the increasing number of victims of car accidents and gunshot and stab wounds, in whom almost 20% of cardiac arrests of this study were observed, have certainly contributed to the increased number of cardiac arrests caused by physical status changes.

The higher incidence of cardiac arrests during anesthesia in male patients (twice as compared to females) found in our survey (Table III) follows the same trend of other surveys ^12,16-23. Males seem more predisposed to trauma, violence and vascular diseases as compared to females, which may justify our results.

Cardiac arrest is related to poorer physical status (ASA III to V) and to the level of urgency and especially emergency of the procedure. So, mortality rates in patients submitted to emergency surgeries are always higher as compared to elective surgeries ^{7,11,13,16,19,21-23,31,32}, the same being true for ASA IV or V patients ^11,16,23,25. Our study has also observed a 12-fold higher incidence of cardiac arrest in emergency surgeries as compared to routine surgeries (Table V) and 227-fold lower incidence in ASA IV patients as compared to ASA I (Table IV).

In our study, the highest number of cardiac arrests was observed in neonates, in the ratio of 9:1 as compared to young adults; in patients above 50 years of age, in the ratio of 38:1 as compared to young adults; while the lowest incidence of cardiac arrests was observed in children aged 1 to 12 years, in adolescents aged 13 to 17 years and in young adults, aged 18 to 25 years (Table II).

Studies have shown that patients in extreme age brackets are more predisposed to cardiac arrests. So, neonates and children, especially in their first year of life, the presence of prematurity, of congenital heart disease, of congenital neurological disease and of other congenital disorders, seems to place them at higher anesthetic risk as compared to older children and young adults ³⁰. Advanced age also increases in 15 to 20 times the risk for cardiac arrest ^{11,13,18,20,21,25}.

Most recent studies in Australia ¹⁶, France ²⁰, the Netherlands ¹⁹, United States ^25,30 and Brazil ²³, have shown a lower incidence of cardiac arrests and deaths in children aged 1 to 12 years. However, the number of cardiac arrests and deaths related to anesthesia as from 50 years of age seems to be increasing, peaking between 70 and 80 years, especially during hip and hip joint fracture surgery ^{16,25,30,32,33}. It should be stressed that the number of anesthesias in patients aged 80 or even 90 years is increasingly higher.

It should also be stressed that age brackets from 13 to 17 years and from 18 to 35 years have presented the lowest incidence of cardiac arrest, respectively of 13 and 15:10,000 anesthesias. These, however, were mostly seen in young males, victims of car accidents or gunshot or stab wounds.

Cardiac arrest related to type of anesthesia has shown a 19-fold higher incidence for general anesthesia as compared to spinal blocks (Table VI). Other authors ^{12,18,19,23,25} have also found similar results. When comparing with the previous survey ¹⁸, it has been observed that the incidence of cardiac arrest during general anesthesia has remained virtually the same - 50:10,000 anesthesias - while its incidence during spinal and epidural anesthesias has decreased from 4.4:10,000 to 2.65:10,000 anesthesias. The largest and most recent prospective study ever performed has shown an incidence of cardiac arrest during spinal anesthesia of 2.7:10,000 anesthesias ³⁴.

Currently, with enhanced knowledge of spinal blocks physiology, with safer local anesthetics with fewer side effects, associated to increased oxygen monitoring through pulse oximetry has highly decreased the possibility of major complications during spinal blocks.

However, spinal block-related cardiac arrest is still seen, although uncommonly as shown by this survey, with incidence of 0.02% (Table VI), especially in elderly patients. Fortunately, there has been no cardiac arrest related to anesthesia as the triggering factor in patients submitted to spinal blocks (Table VIII), differently from a previous study ¹⁸ where there have been five cardiac arrests with spinal anesthesia as the triggering factor.

In this survey ¹⁸, developed in the period 1988 to 1995, most spinal anesthesias were not monitored with pulse oximetry, which was only routinely used as from 1991. It should be considered that epidural and spinal blocks are not indicated for patients with hemodynamic instability, fact which might have contributed for the lower incidence of cardiac arrests with this type of anesthesia.

As to regional blocks, the lack of cardiac arrests was to be expected. Studies have shown that in this type of anesthesia, because there are no major respiratory and cardiocirculatory systems changes, cardiac arrest is almost null ²⁰.

In terms of surgical specialty, there has been a higher number of cardiac arrests in poli-trauma patients jointly treated by several clinics, and in heart, chest, vascular and pediatric surgeries. These results are in line with the literature ^17,18,23.

As to deaths, there has been an incidence of 21.7:10,000 anesthesias, that is, virtually the same incidence of a previous study ¹⁸, which has been 21.2:10,000 anesthesias. This incidence is lower than that found by other Brazilian studies, which varies 19 to 51:10,000 anesthesias ^12,17,23. The incidence of cardiac arrest reported by other countries varies 1.1 to 30:10,000 anesthesias ^{5,9,10,13,20-22,24,25,28,30,32} .

As to death triggering factors, it has been observed that anesthesia alone or associated to other factors has also been the less important factor, with incidence of 0.98:10,000 (Figure 2) and with lower mortality as compared to other triggering factors. In the previous study ¹⁸, there has been a slightly lower incidence of deaths of 0.85:10,000 anesthesias.

As compared to other authors, our results are within the mean found, especially as from the 90s, which is less than 1 death for 10,000 anesthetic procedures.

Since the pioneer study by Beecher et al. ³⁵, covering the period 1948-1952, who have reported incidence of death of 1:1560 anesthesias when anesthesia was a major contributing factor, and of 1:2680 anesthesias when anesthesia was the primary cause of death, there has been almost a 10-fold decrease in mortality by anesthetic causes. Even when considering differences in patients' risk and complexity of surgeries performed 50 years ago, we have concluded that in the last decades there has been a dramatic increase of anesthetic safety.

A study carried out in France has shown major increase in the number of annual anesthetic procedures from 1980 to 1996, which has gone from 6.6 to 13.5 for every 100 people. As major aspects, it has been observed that the highest increase was among elderly and physical status ASA III-V patients ³⁶. If this is a worldwide trend, it may indicate increase in Anesthesiology safety. These aspects have transformed advances in Anesthesiology safety into a model in which other specialties are encouraged to establish strategies to obtain similar risk decrease ^37,38.

Some authors ²² have stressed that the incidence of mortality by anesthetic factors has been maintained stable in the last decade. The mean of studies performed in this period has shown an incidence of anesthesia-related deaths of 1:13,000 anesthesias involving physical status ASA I to V patients ²². However, this decrease is still not good enough, because the ideal would be that no patient would die from anesthetic causes, as already stated by Macintosh in 1948 ³⁹.

Lagasse ²², correctly stresses that anesthesia is not yet totally safe for physical status ASA I or II patients, in whom iatrogenic factors may be major risks, and even less for sick patients. Unfortunately anesthesia still contributes for severe adverse events and avoidable deaths.

So, would anesthesia safety have reached a plateau? Data from our survey and studies from the 80s and 90s point to this possibility.

In our survey, when analyzing cardiac arrest and death with anesthesia as triggering factors, we have observed that ventilatory problems are still the most important causes, overcoming cardiocirculatory changes. This aspect has been reported by several authors ^18,23,25-30, despite the introduction of pulse oximetry and capnography in the clinical practice, which are safety monitors of the respiratory device.

Another aspect to be highlighted is the number of drug-related cardiac arrests and deaths, which has been seen in three cardiac arrests and was responsible for one death. Morray et al. ³⁰ have shown that 37% of all cardiac arrests in children were related to medication. Newland et al. ²¹ have observed in a broad study involving all age brackets that 40% of cardiac arrests were related to anesthesia and drugs used. No drug-related case in this study has involved misuse of drugs, but rather anesthetic overdose or unusual response to standard doses. In a previous survey ¹⁸ there have been two cardiac arrests secondary to epinephrine misuse.

An important aspect to be stressed is the institutionalization of safety programs by Scientific Societies and Committees, creating algorithms related to basic monitoring, difficult tracheal intubation, cardiopulmonary resuscitation and training in simulators. But there is still the need to pursue the principle that "there is no anesthesia-related life threat" with the passion it still demands.

In conclusion, the incidence of cardiac arrests during anesthetic-surgical procedures is still high. The number of cardiac arrests and deaths caused by changes in patients' physical status is increasingly high, while the number determined by surgery and anesthesia is progressively decreasing. Anesthesia-related deaths seem to have reached a plateau, which has not decreased in the last decade. There is a higher incidence of cardiac arrests in neonates, children below 1 year of age, patients above 50 years of age and elderly, in males, in patients physical status ASA III to V, in emergency surgeries, in those involving several clinics and in heart, chest, vascular and pediatric surgeries.

REFERENCES

Submitted for publication January 5, 2004

Accepted for publication May 25, 2004

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*

Received from CET/SBA do Departamento de Anestesiologia da Faculdade de Medicina de Botucatu (FMB UNESP), Botucatu, SP; Prêmio Dr. Renato Ribeiro concedido pela Sociedade Brasileira de Anestesiologia em 2003

Publication Dates

• Publication in this collection
  26 Jan 2005
• Date of issue
  Dec 2004

History

• Accepted
  25 Jan 2004
• Received
  05 Jan 2004