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Preoperative stress testing improves non-cardiac surgery outcomes in high-risk patients
31/01/2010 16:13
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MedWire News: Preoperative noninvasive cardiac stress testing is associated with improved 1-year survival and reduced hospital stay in patients undergoing elective non-cardiac surgery who are at high risk for cardiac complications, a large population-based study has found.
Stress testing was associated with only minor benefits in patients with patients with intermediate risk for cardiac complications, however, and with harm in those at low risk.
The findings reaffirm current American College of Cardiology and American Heart Association guidelines that recommend preoperative stress testing only in individuals with clinical risk factors for complications.
Despite these recommendations, some experts have discouraged any use of preoperative stress testing because it may delay surgery, instead advocating routine perioperative beta-blocker therapy, explain Duminda Wijeysundera (University of Toronto, Ontario, Canada) and co-authors of the current study.
However, the finding of no significant effect of preoperative stress testing on outcomes in the DECREASE II randomized trial had wide confidence intervals, they point out, while studies have also raised concerns over the safety of perioperative beta-blockade.
Given the lack of proved impact on outcomes, Wijeysundera and team used linked administrative databases to study Ontario residents aged 40 years or older who underwent elective surgery from 1994 through 2003.
Of a total of 271,082 patients included in the study cohort, 23,991 (8.9%) underwent stress testing, the authors report in the British Medical Journal.
Overall, patients who underwent stress testing had a significant 8% lower relative 1-year mortality rate (p=0.03) and 0.24-day shorter mean hospital stay (p<0.001) in comparison with a propensity-score matched cohort of 46,120 patients who did not.
Further analysis revealed that the effects of testing on mortality varied with patients’ baseline risk for cardiac complications, as indicated by Revised Cardiac Risk Index (RCRI) class which comprises the equally weighted risk factors ischemic heart disease, heart failure, cerebrovascular disease, diabetes, renal insufficiency, and high-risk surgery (intra-abdominal, intrathoracic, or suprainguinal vascular procedures).
Preoperative stress testing was associated with increased mortality in low-risk patients (RCRI 0 points), at a hazard ratio (HR) of 1.35, but with improved survival in intermediate-risk patients (RCRI 1–2 points) and high-risk patients (RCRI 3–6 points), at HRs of 0.92 and 0.80, respectively.
These values corresponded to a number needed to harm of 179 in low-risk patients and numbers needed to treat to prevent mortality at 1 year of 156 for intermediate-risk patients and 38 for high-risk patients.
Putting the latest findings in context, Davy Cheng (University of Western Ontario, London, Canada) said in a related editorial: “Overall, the evidence suggests that preoperative noninvasive stress testing should be reserved for high-risk patients, and that the survival benefits probably result from pharmacological intervention and monitoring rather than coronary intervention before non-cardiac surgery.
“Whether preoperative stress testing provides prognostic benefits in specific groups of patients at intermediate risk is unclear, but it should not be ordered in low-risk patients.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
BMJ 2010; 340: b5526
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Portador de Marcapasso na Cirurgia Geral - Atitudes para reduzir complicações
10/01/2010 21:18
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Os marcapassos podem apresentar perda de comando durante a cirurgia por causas diferentes. As mais frequentes são as interferências ELETROMAGNÉTICAS, as MUSCULARES esqueléticas ( miopotenciais ) e as modificações agudas no gradiente transmembrana da célula miocárdica ( K+ ).
Na prática, agentes anestésicos inalatórios não mostram qualquer efeito sobre o limiar de estimulação.
1- Utilizar um eletrocautério bipolar, se possível.
2- Utilizar a menor potência ( corrente ) efetiva.
3- Nunca posicionar a placa de aterramento do eletrocautério de modo que o gerador fique situado entre a placa-terra e o local da cirurgia. Direcionar a corrente para longe do gerador.
4- Posicionar a placa de aterramento de modo que o gerador NÃO fique na linha formada entre o campo cirúrgico e a placa. Essa linha NÃO deve ser paralela à linha traçada entre o eletrodo do marcapasso no ventrículo e o gerador. Isso é mais crítico para marcapassos unipolares.
5- Não ativar o eletrocautério até estar pronto para utilizá-lo. O eletrodo ativo do eletrocautério não precisa estar em contato com o paciente para induzir interferências no gerador.
6- Não utilizar o cautério em distância inferior a 5cm do marcapasso. Distâncias maiores que 12cm são mais seguras.
7 Uma fonte magnética também pode interferir na função do marcapasso.
Fonte: Temas de Marcapasso - Celso Salgado de Melo. |
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MEDICAMENTOS: Recomendações Especificas - Extraido de ¨Risco Cirúrgico¨ Rotinas de Avaliação, Andrea Costa da Silva Butler... Et all-Guanabara Koogan-2005
04/08/2009 20:17
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MEDICAMENTOS – Recomendações Especificas **
AAS -------------------------------------------- -Suspender 7 a 10 dias nates da cirurgia
AINH------------------------------- ------------- Suspender 48 a 72 horas antes da cirurgia. Atentar Função Renal.
ANTIPARKINSONIANOS------------------------- Não suspender; avisar anestesista. Principalmente se o paciente estiver usando inibidores da MAO.
BETA-BLOQUEADOR---------------------------- Nunca suspender; iniciar de acordo com os critérios de Magano/Boersma: coronariopatia conhecida ou 2 ou mais: colesterol total>200mg/dl, hipertensão arterial, idade >65 anos, diabetes nelito, insuficiência renal, AVC e AIT. VER considerações do DCC/GAPO-SBC neste site-Beta-bloqueadores.
CLONIDINA----------------------------------- Nunca suspender
CLORPROPAMIDA------------------------- Suspender no dia anterior
CORTICOESTERÓIDES-------------------- Reposição perioperatória; verificar potássio sérico.
CUMARÍNICOS----------------------------- Suspender 4 a 5 dias antes da cirurgia; liberar com INR <1,5; Evitar reversão da anticoagulação com vitamina K. VER excelente artigo Dra Renata neste site.
DIURÉTICOS ------------------------------- Suspender no dia da cirurgia; avaliar potássio sérico.
GLIBENCLAMIDA ------------------------ Suspender no dia da cirurgia.
HEPARINA--------------------------------- Plena em bomba infusora: suspender 6 horas antes; Plena SC: suspender 12h antes ( checar PTT na manhã da cirurgia ); liberar com PTT < 1,5; Baixo peso: suspender 12h antes.
INIBIDORES DA COX-2----------------- Não é necessário suspender; cuidado com disfunção renal.
INIBIDORES da ECA-------------------- Nunca suspender
PSICOTRÓPICOS------------------------ Manter na maioria dos casos.
TICLOPIDINA---------------------------- Suspender 14 dias antes.
** Extraido de ¨Risco Cirúrgico – Rotinas de Avaliação, Andrea Costa da Silva Butler... Et all-Guanabara Koogan-2005 |
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Alteração no perfil de coagulação e incidência de TVP em colecistectomia laparoscópica
03/08/2009 13:32
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Embora a colecistectomia laparoscópica parecer ser menos traumática aos pacientes, comparada à cirurgia aberta, a diminuição do retorno venoso dos membros inferiores e a hipercoagulabilidade que ocorre em pacientes submetidos à colecistectomia laparoscópica eletiva com pneumoperitônio por CO2 torna-se um fator de risco potente para a ocorrência de trombose venosa profunda (TVP).
Pesquisadores publicaram, recentemente, no International Journal of Surgery, um estudo observacional de 50 pacientes submetidos à colecistectomia laparoscópica eletiva, desenhado para avaliar alterações de TP, TTPa, D-dímero e antitrombina III, que foram medidos no pré-operatório, 6h e 24h após a cirurgia. Os pacientes foram acompanhados por ultrassom colorido duplex dos membros inferiores bilateralmente e no 7º pós-operatório para procurar por evidências de TVP.
Diminuição significativa pós-operatória de TTPa e de antitrombina III sugeriram ativação da coagulação, enquanto que a diminuição do D-dímero sugeriu ativação da fibrinólise. Valores de TP não apresentaram alterações estatisticamente significativas pós-operatórias. Idade, índice de massa corpórea e duração do pneumoperitônio correlacionaram-se à ativação significativa da coagulação e da fibrinólise. Nenhum paciente desenvolveu evidências clínicas ou radiológicas de TVP no período pós-operatório.
Os pesquisadores concluíram que o pneumoperitônio por CO2 aumenta a ativação da coagulação e da fibrinólise associadas à colecistectomia laparoscópica. Pacientes com fatores de risco como idade avançada, obesidade ou com expectativa de longa duração de cirurgia laparoscópica tendem a ter ativação significativa da coagulação, tornando-os um grupo de risco vulnerável ao desenvolvimento de TVP no pós-operatório, justificando a utilização de alguma forma de tromboprofilaxia.
Uma resenha de Alteration in coagulation profile and incidence of DVT in laparoscopic cholecystectomy - International Journal of Surgery; 2008 Dec 25. [Epub ahead of print]
Caso deseje receber o trabalho na íntegra, por favor contacte nosso serviço de Informações Médicas pelo nosso site ou através do 0800 7030015.
As resenhas são baseadas em artigos de periódicos nacionais e internacionais que contenham informações médicas com aplicabilidade prática.
Copyright ® 2008: São Paulo Medical Conferences - Todos os direitos reservados sobre a resenha em português.
"O conteúdo desta página é de responsabilidade da São Paulo Medical."
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RISCO CIRURGICO
03/08/2009 09:20
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| RISCO CIRÚRGICO: ROTINAS DE AVALIAÇÃO |
| ANDREA COSTA DA SILVA BUTLER, CLAUDIA ABREU COSTA, CLAUDIA REGINA LOPES CARDOSO, ET AL. |
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| AVALIAÇÃO CLÍNICA PRÉ-OPERATÓRIA - RISCO CIRÚRGICO |
| RUI PÓVOA |
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Antibiotic Prophylaxis Against Infective Endocarditis: New Guidelines, New Controversy?
02/08/2009 15:31
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Richard G. Bogle; Abhay Bajpai
Br J Cardiol. 2008;15(6):279-280. ©2008 Medinews (Cardiology) Limited
Posted 01/12/2009
Introduction
For over 50 years cardiologists have routinely recommended antibiotic prophylaxis (ABP) at the time of dental procedures in patients deemed to be at risk of infective endocarditis (IE). Reviews and editorials all acknowledged the lack of robust evidence for effectiveness of ABP and from time to time the literature has been reviewed and expert opinion synthesised into guidelines. In the UK, the 2004 Joint Royal College of Physicians/British Cardiac Society guideline has been widely followed.[1] In 2006 new guidelines were published by the British Society for Antimicrobial Chemotherapy (BSAC).[2] These guidelines were important because this committee's recommendations are incorporated into the British National Formulary. The BSAC guidelines recommended withdrawal of ABP for the majority of patients limiting them to individuals perceived to be at the highest risk of IE (e.g. a prior history of IE, prosthetic cardiac valves and surgically constructed pulmonary or system shunts/conduits). These guidelines were welcomed by the majority of dentists and microbiologists as a step in the right direction. However, many cardiologists, who had seen first-hand the horrors of IE, did not wish to see the rejection of a therapy that was thought by most to be effective and harmless. The lack of agreement between the medical and dental professions resulted in the issue being referred to the National Institute for Health and Clinical Excellence (NICE) for an authoritative statement.[3]
NICE Guidance
The NICE review tried to determine which cardiac conditions are associated with increased risk of IE; whether dental treatment is associated with acute risk of developing the condition and whether ABP was effective in prevention of cases and deaths. The NICE guideline concluded that patients with structural heart disease were at increased risk of IE but did not find convincing evidence that dental ABP was cost-effective. They calculated that if amoxicillin prophylaxis was effective then the cost of preventing a single case of IE would be circa £12 million. In the absence of high-quality evidence for clinical effectiveness they recommended that routine dental ABP should be abandoned. The methodology employed by NICE was robust and transparent, in contrast to the evidence supporting ABP. The NICE guidelines development group usually review therapies supported by data from mega-trials and meta-analyses, however, the literature on ABP is more like the Dead Sea scrolls - fragmented, imperfect, subject to various interpretations and mainly missing. In this situation there is a strong reliance on expert opinion and many would agree that absence of evidence should not be regarded as evidence of absence. The poor quality of the supportive data and reliance on expert opinion probably explains the differences between the BSAC and American Heart Association/American College of Cardiology (AHA/ACC) guidelines and those of NICE. The NICE guideline development process is transparent and the comments from stakeholders are published. Review of these comments shows that the dental community is generally in favour of the new recommendations, which reinforce the link between good overall dental hygiene and prevention of IE rather than relying on ABP just at the time of dental work. Other stakeholders are concerned not only with the guideline itself but potential difficulties with implementation. In this respect the Department of Health stated that the guidelines were a "very significant shift in current clinical practice... we feel there is a serious risk of confusion and lack of compliance".
Reaction
The reaction to these guidelines has been predictable. Many cardiologists see them as a step too far and question the credibility of a guideline that is based around the reevaluation of weak historical evidence rather than high-quality clinical trials. To many cardiologists the case supporting ABP is simple: IE is a very serious disease with a high mortality and morbidity; decades of clinical experience have illustrated that certain patients are at increased risk; dental work is associated with bacteriaemia and antibiotics kill bacteria cheaply, effectively and with low toxicity. Most cardiologists acknowledge the lack of definitive evidence for effectiveness but believe that even if ABP prevents only a minority of IE, surely this is preferable. It is for these reasons we believe that most cardiologist are uneasy about the new guidelines. Of course we may never be able to measure the precise effectiveness of ABP and this uncertainty was acknowledged more than 25 years ago by Celia Oakley and Walter Somerville who hypothesised at least four reasons why ABP might fail:[4]
- Perhaps it was not given.
- Perhaps it was not given to the right people.
- Perhaps it does not work.
- Perhaps it is irrelevant.
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Now that the guideline has been published various scenarios and difficulties may be envisaged. For example, if a cardiologist continues to recommend ABP for a patient but the dentist wants to follow the NICE guidelines. Each clinician has a separate duty of care to the patient and both may feel they are acting within the patient's best interest. While the view expressed by the cardiologist is a valid consideration, legally it is not definitive and would only be taken as part of the overall 'mix' of information. The Dental Protection organisation has already advised their members that if a cardiologist continues to recommend ABP it is inadvisable, as it conflicts with guidelines issued by an authoritative body; this recommendation holds even if it has been confirmed in writing by the cardiologist.[5]
The Art of Medicine
A survey of cardiologists, prior to the publication of the NICE guidelines, showed that 94% felt that patients with moderate risk of IE should receive ABP and 96% believed that it was unsafe not to recommend ABP to such patients prior to dental treatment.[6] With such overwhelming support for the status quo what is the legal position of the cardiologist who decides to act against the guideline? The Bolam defence stated that a doctor is not guilty of negligence if "he has acted in accordance with a practice accepted as proper by a responsible body of medical men skilled in that particular art".[7] Since NICE is a national body appointed by statute it is likely to be regarded as a responsible body. Although NICE guidelines are not enforceable in law the threat of legal action might lead cardiologists, while not agreeing with the guidelines, to comply with them since any potential legal action could be robustly defended. However, compliance with guidelines due to a fear of litigation could, in time, weaken the Bolam defence due to a lack of variation in practice. Over 2,000 years ago, Plato explored the difference between skills grounded in practical expertise and those based solely on following instructions or obeying rules. He argued that once the medical profession dedicates itself to the provision of healthcare through guidelines it is committed to continue observing them because, at that point, the expertise resides within the guidelines rather than the clinician. Once this occurs then any guideline deviation is unjustifiable on the basis of clinical judgement.
In clinical cardiology we are used to facing decisions where the clinical evidence base does not completely apply to the particular patient at hand. In this situation we give an opinion - a belief based not on positive knowledge but on what seems valid, true, or probable to one's own mind. It is time for cardiologists to do that with ABP. If we believe, as a group, that NICE has gone too far in recommending the abolition of ABP then we should act together as a responsible body of doctors robustly defending the Bolam principle and our right to clinical judgement
References
- Ramsdale DR, Turner-Stokes L. Prophylaxis and treatment of infective endocarditis in adults: a concise guide. Clin Med 2004;4:545-50.
- Gould FK, Elliott TS, Foweraker J et al. Guidelines for the prevention of endocarditis: report of the Working Party of the British Society for Antimicrobial Chemotherapy. J Antimicrob Chemother 2006;57:1035-42.
- National Institute for Health and Clinical Excellence. Prophylaxis against infective endocarditis: NICE guidance. London: NICE, 2008. Available from: http://www.nice.org.uk/Guidance/CG64
- Oakley C, Somerville W. Prevention of endocarditis. Br Heart J 1981;45:233-5.
- Dental Protection. Antibiotic cover for dental procedures - frequently asked questions. Available from: http://www.dentalprotection.org/assets/documents/ 2008_DPL_FAQ_Antibiotic_Prophylaxis_0308.pdf
- Ramsdale DR, Egred M, Palmer ND, Chalmers JAC. Antibiotic prophylaxis to prevent infective endocarditis should be given to patients. Heart 2007;eletter. Available from: http://heart.bmj.com/cgi/eletters/93/6/753-a#1477
- Bolam v Friern Hospital Management Committee 1957. Available from: http://oxcheps.new.ox.ac.uk/casebook/Resources/BOLAMV_1%20DOC.pdf
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Beta-bloqueadores no perioperatório de intervenções não cardíacas - os novos dados do estudo POISE
02/08/2009 15:25
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No dia 13 de maio a revista britânica The Lancet publicou, em seu site os resultados do estudo POISE e com isso iniciou um intenso debate que envolveu médicos, repórteres e pacientes. O estudo POISE é, até agora, o maior estudo clínico já realizado para investigar o papel dos beta-bloqueadores no perioperatório de intervenções cirúrgica não-cardíacas. Os mais de 8.000 indivíduos incluídos foram aleatorizados para receber metoprolol ou placebo. É importante salientar que somente as intervenções cirúrgicas eletivas foram analisadas e pacientes que já faziam uso de beta-bloqueador por outras razões, não foram incluídos neste estudo. Com relação aos desfechos cardiovasculares, como morte cardíaca e infarto não fatal, o POISE revelou resultados semelhantes aos estudos anteriores com menos pacientes: o grupo que recebeu metoprolol apresentou incidência de complicações significativamente menor do que o grupo controle. Por outro lado, o que chamou a atenção dos investigadores foi o resultado da análise dos desfechos secundários, morte por todas as causas e acidente vascular cerebral (AVC). Nesta análise, os pacientes que receberam metoprolol apresentaram taxas maiores de complicações. Segundo os autores, a hipotensão e a bradicardia, mais frequentes no grupo que recebeu metoprolol, teriam sido responsáveis pela maior ocorrência de complicações, em especial AVC. A interpretação desses dados fez os investigadores do POISE concluírem que o uso de metoprolol no ambiente perioperatório é capaz de reduzir a chance de complicações cardiovasculares, MAS a um custo muito elevado: aumento da chance de morte ou de AVC. Os autores do trabalho acrescentaram que as recomendações relativas ao uso de beta-bloqueadores contidas nas diretrizes de tratamento perioperatório deveriam ser reformuladas. O editorial que acompanha o artigo recomenda, entretanto, cautela com relação a esta decisão. Aponta problemas com relação à escolha da dose de metoprolol adotada pelo estudo POISE (100 mg na primeira dose, atingindo 200 mg por dia) ou seja, 50% da dose máxima permitida para esse medicamento. Segundo o editorial, esta dose é muito mais alta do que a utilizada em estudos anteriores, o que poderia explicar a ocorrência de hipotensão e bradicardia. De fato, a análise dos dados do POISE, incluindo o material adicional oferecido pelos autores e disponível no site da revista, revela que não foi desprezível o número de pacientes que desenvolveu hipotensão e bradicardia. Hipotensão e bradicardia, embora possam representar complicações potencialmente graves, quando prontamente reconhecidas e tratadas por meio de suspensão do beta-bloqueador e medidas para elevação da freqüência cardíaca e da pressão arterial, não estão associadas a elevações significativas de taxas de complicações. Estas conclusões provêm de estudos com pacientes na fase aguda do infarto agudo do miocárdio onde os beta-bloqueadores têm seu benefício comprovado, mesmo numa situação onde a hipotensão e bradicardia poderiam reduzir perfusão coronariana e aumentar o tamanho do infarto. Como lidar então com as informações do POISE aparentemente contraditórias aos conceitos arraigados e, mais importante, em conflito com a fisiopatologia das complicações cardiovasculares e com os mecanismos de cardio-proteção dos beta-bloqueadores? Mais uma vez, com cautela. Aqui vão algumas recomendações:
1. Os indivíduos em uso prévio de beta-bloqueador não foram incluídos no POISE. Este indivíduos NÃO devem ter o beta-bloqueador suspenso antes de intervenção cirúrgica não cardíaca.
2. TODOS os indivíduos que fazem uso de beta-bloqueadores no perioperatório de intervenções cirúrgicas não cardíacas devem ser rigorosamente monitorizados com relação à ocorrência de hipotensão e bradicardia. Caso uma destas complicações seja diagnosticada, o medicamento deve ser prontamente suspenso e devem ser estabelecidas medidas para sua correção.
3. Enquanto aguardamos análise mais detalhada dos dados do estudo POISE, recém publicado, as recomendações relativas ao uso de beta-bloqueadores no perioperatório de intervenções cirúrgicas não cardíacas devem ser mantidas.
Bruno Caramelli
Daniela Calderaro
Pai Ching Yu
Danielle Menosi Gualandro
Andre Coelho Marques |
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Preditores Clínicos de Risco Cardiovascular
02/08/2009 15:24
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MAIORES
- Síndromes coronarianas instáveis - IAM agudo ou recente ( <>
- Angina instável ou severa ( classes II a IV da associação canadense )
- ICC descompensada
- Arritmias significantes ( BAV de alto grau, arritmia ventricular com cardiopatia, arritmia supraventricular com alta resposta ventricular de difícil controle )
- Valvulopatia grave
INTERMEDIÁRIOS
- Angina do peito leve ( Classe I e II da associação canadense )
- Infarto do Miocárdio prévio pela história ou pela presença de ondas Q no ECG
- ICC compensada ou insuficiência cardíaca prévia
- Diabete Melito
- Insuficiência Renal
MENORES
- Idade avançada
- ECG alterado ( sobrecarga, bloqueios de ramo, alterações da repolarização, etc )
- Ritmo não sinusal
- Baixa capacidade funciona ( <>
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Perioperative beta-blocker use in noncardiac surgery questioned
02/08/2009 15:21
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MedWire News: Researchers have questioned the use of beta blockers for the prevention of adverse clinical outcomes in patients undergoing noncardiac surgery.
Their meta-analysis found no evidence for any reduction in mortality or heart failure with beta blocker use, while reductions in the risks for nonfatal myocardial infarction (MI) and myocardial ischemia were offset by more than a doubling of the risk for nonfatal stroke.
Querying the validity of current American College of Cardiology and American Heart Association guidelines stating that the weight of evidence, in aggregate, supports the use of beta blockers during noncardiac surgery in high-risk patients, Franz Messerli (Columbia University, New York, USA) and team critically reviewed 33 relevant randomized, controlled trials involving over 12,000 patients.
In an advance online publication by The Lancet time to coincide with presentation of the findings at the AHA annual scientific sessions in New Orleans, Louisana, they report that beta blockers were not associated with any significant reduction in the risk for all-cause mortality, cardiovascular mortality, or heart failure.
Beta blockers were associated with significant 35% and 64% reductions in the risks for nonfatal MI and myocardial ischemia, giving numbers needed to treat of 63 and 16, respectively. But these reductions were seen at the expense of the two-fold increase in nonfatal strokes, giving a number needed to harm of 293.
Patients who received beta blockers also had an increased risk for bradycardia and hypotension, at numbers needed to harm of 22 and 17, respectively.
“Beta blockers should not be routinely used for perioperative treatment of patients undergoing noncardiac surgery unless patients are already taking them for clinically indicated reasons,” the authors conclude in their article.
Eric Boersma and Don Poldermans, from the Erasmus Medical Center in Rotterdam, The Netherlands, said in an accompanying Comment article that the net clinical outcome of beta blocker treatment should not be based on the sum of its effects found in the study.
But they call for investigators to release data about clinical conditions and perioperative hemodynamic changes that may have resulted in the observed complications.
“These data will be key for updates of treatment guidelines,” they concluded.
Lancet 2008; Advance online publication |
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Heart rate control with beta blockers ?impacts surgical outcomes?
02/08/2009 15:20
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21 October 2008
MedWire News: Perioperative beta-blockade (BB) is associated with higher rates of death and myocardial infarction (MI) at 30 days, a retrospective study of noncardiac patients has found.
Interestingly, BB-treated patients who died had higher preoperative heart rates than their surviving counterparts, a finding that highlights the importance of achieving adequate heart-rate control during noncardiac surgery.
The study, by Haytham Kaafarani (University of South Florida, Tampa, Florida, USA) and co-workers, investigated the relationship between BB use, heart rate control, and perioperative cardiovascular outcomes in patients undergoing various noncardiac surgical procedures.
The patients exhibited a broad spectrum of cardiac risk, Kaafarani et al remark. This is relevant as there is ongoing controversy about the optimal use of perioperative BBs in patients at various levels of cardiac risk.
In all, 238 patients taking BBs at the time of surgery were matched by age, gender, cardiac risk, procedure risk, smoking status, and renal function, with 408 patients not taking BBs.
At 30 days post-surgery, the BB group had significantly higher rates of MI (2.94% vs 0.74%, p=0.03) and death (2.52% vs 0.25%, p=0.007) compared with controls. None of the deaths occurred among patients classified as high cardiac risk.
The BB group had lower preoperative and intraoperative heart rates at all levels of cardiac risk; within the BB group, patients who died had significantly higher preoperative heart rates (86 vs 70 beats per minute, p=0.03) compared with survivors.
“As subtle as it may be, this finding suggests that a low target preoperative rather than intraoperative heart rate is essential for the protective effect of beta blockers,” the authors write.
“The relationship between preoperative (rather than intraoperative or postoperative) heart rate and perioperative mortality stresses the importance of not only initiating but also titrating the effect of beta blockers to an acceptable target heart rate before surgery.”
In accompanying Invited Critique, Todd Rasmussen (Wilford Hall USAF Medical Center, San Antonio, Texas, USA) congratulates Kaafarani et al on their “insightful” study but suggests that residual confounding may have accounted for the difference in MI and survival rates between the groups.
“Without more detailed and uniform risk-stratification of patients in both groups, accounting for this bias is difficult, if not impossible,” he remarks. “I would encourage [the authors] to now turn their energy and expertise to a contemporary cohort using more powerful and complete methods.”
Arch Surg 2008; 143: 940–944 |
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