Cardiac

Volatile Anesthetics vs. Total Intravenous Anesthesia for Cardiac Surgery

The ‘cardioprotective’ effects of volatile anesthesia gases have been seen as useful during coronary artery bypass surgery (CABG). This controlled study in elective CABG compared volatile anesthesia with total intravenous anesthesia (TIVA) and found no difference in 30 day or 1 year mortality.

The findings are important as anesthetic gases have been even recommended as useful in American and European guidelines, based on known cellular protective effects and effects on cardiac biomarkers, and suggested by previous observational and meta-analysis studies.

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Lidocaine and Neurologic Outcomes after Cardiac Surgery

50% of cardiac surgery patients leave hospital with cognitive dysfunction which tends to improve but may persist at 5 years in some. Based on previous suggestion that Lidocaine may ameliorate such issues due to postulated anti-inflammatory, blood flow, and cerebral metabolism mechanisms, this randomized study failed to find benefit with use of Lidocaine infusion during and for 48 hours after cardiac surgeries.

Conclusion: Intravenous lidocaine administered during and after cardiac surgery did not reduce postoperative cognitive decline at 6 weeks.

The authors note the complex issues involved in cognitive dysfunction that could not be expected to benefit from a single agents – preoperative cognitive impairment, genetic predisposition, cerebral microembolism or hypoperfusion during CPB, inflammatory responses, hemodilution, hyperglycemia, hyperthermia, unmasking of Alzheimer disease, and acceleration of amyloid deposition associated with inhalational anesthetics.

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Perioperative Hypotension and Cardiovascular Events

Another study adds to the now established theme that perioperative hypotension increases cardiovascular events and does so independently of the degree of coronary artery disease.

Hypotension is defined in this study as systolic blood pressure < 90mm Hg for at least 10 mins. Other studies have also used mean arterial pressure < 65.

The nuances show the effects were additive if not multiplicative. There was insufficient evidence that perioperative hypotension may have less deleterious cardiovascular effects in patients with a lesser degree of coronary artery disease compared to greater coronary artery disease.

“These data support efforts for the prevention, monitoring, and treatment of perioperative hypotension regardless of the presence or absence of significant coronary artery disease”.

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Methylprednisolone for AKI in Cardiac Surgery

A sub study of a randomized trial finds: “Intraoperative corticosteroid use did not reduce the risk of acute kidney injury in patients with a moderate-to-high risk of perioperative death who had cardiac surgery with cardiopulmonary bypass. Our results do not support the prophylactic use of steroids during cardiopulmonary bypass surgery”.

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A previous review casts doubt on the use of steroids for various purposes in cardiac surgery, finding that they had “an unclear impact on mortality, increased the risk of myocardial injury, and the impact on atrial fibrillation should be viewed with caution given that large trials showed no effect”. link

Intraoperative Blood Pressure and Outcome

A consensus statement reflects numerous studies suggesting the harms of even brief episodes of intraoperative hypotension. There is strong associations between hypotension and myocardial injury and infarction, renal injury, and death.

The consensus defines significantly harmful levels as systolic < 100, or mean arterial pressure < 60 – 70mm Hg in noncardiac surgery. Upper levels of 160 (or 140 in cardiac surgery) increase the risks.

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Some of the studies showing the harms of hypotension previously published:

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Heart Failure and Surgical Mortality

Heart Failure is a recognized red flag for surgical risk. This retrospective study sought to quantify the risk in over 600,000 patients undergoing non-cardiac surgery. The findings showed that crude 90-day mortality for patients with heart failure and symptoms was 10.1%; for patients with heart failure and no symptoms, 4.9%; and for patients without heart failure, 1.2%.

The important message is that in heart failure even without symptoms, mortality is higher.

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Peripartum Cardiomyopathy

Of interest to obstetric anesthesiologists, a BMJ current review of this rare but serious dilated cardiomyopathy with systolic dysfunction that presents in late pregnancy or, more commonly, the early postpartum period.

Risk factors include black ancestry, pre-eclampsia, advanced maternal age, and multiple gestation pregnancy. Half recover but many more are left with chronic disease and a minority require mechanical support and/or transplantation.

Features are common to heart failure, and also include arrhythmias and thromboembolism (anticoagulation for which will impact neuraxial anesthesia). General treatment measures are discussed and potential specific treatments, including Bromocriptine for Prolactin inhibition, a postulated mechanism in etiology.

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Delays in CPR and Outcome

The basic message of this study is delay in starting CPR, as well as delay in subsequent Defibrillation or Epinephrine administration worsens prognosis. Witnessed, index cases of cardiac arrest from the Get With The Guidelines– Resuscitation Database occurring between 2000 and 2008 in 538 hospitals were included in this analysis.

Some novel nuances include: delay in CPR led to lower survival even if total time to defibrillation or Epinephrine was the same from cardiac arrest. But delays in defibrillation or Epinephrine after CPR initiation also worsened outcome.

5.7% (3,283 of 57,312) of patients did not have instantaneous initiation of CPR upon determination of a pulseless cardiac arrest. There is a need to determine how these figures can be improved.

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Steroid Use after Cardiac Arrest

Studies have investigated adrenal insufficiency after cardiac arrest and tend to suggest benefits for the use of steroids.

In this retrospective observational study, post-arrest steroid use during hospitalization was associated with better survival to hospital discharge and 1-year survival.

Clearly the findings mandate randomized controlled studies to confirm such benefits.

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Intra-Aortic Balloon Pumps

Intra-aortic balloon pumps have been used empirically for decades for cardiogenic shock in acute myocardial infarction and this study again finds no mortality benefit. They conclude: “IABP has no effect on all-cause mortality at 6-year long-term follow-up. Mortality is still very high, with two thirds of patients with cardiogenic shock dying despite contemporary treatment with revascularization therapy”.

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The study and its implications are discussed further in an accompanying editorial link