Cardiac

Trans-Nasal Evaporative Intra-arrest Cooling

Much of the earlier enthusiasm for therapeutic hypothermia has been tempered with disappointing trial results. This study examined cooling of the brain initiated during cardiopulmonary resuscitation and its impact on survival with good neurologic outcome in patients with out-of-hospital cardiac arrest.

Trans-nasal evaporative intra-arrest cooling did not result in a statistically significant improvement in survival with good neurologic outcome.

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Off or On Pump CABG

Much hope for improvement in outcomes and cognitive impairment was held out for off pump CABG. This study shows no difference.

“The present study’s data did not show differences in key long-term outcomes between patients who underwent revascularization with or without cardiopulmonary bypass, supporting the idea that both methods achieve similar late results regarding overall survival, need for reintervention, and postoperative myocardial infarction.”

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Incentive Spirometry after CABG

The ubiquitous incentive spirometer for breathing exercise after surgery has often been questioned as lacking evidence. Many prehabilitation programs use structured deep breathing as well as inspiratory muscle strength training, along with aerobic and resistance training. Australian choosing wisely physiotherapy guidelines recommended against incentive spirometry ( link ).

This was a single center randomized trial in coronary artery bypass surgery which aimed to improve adherence by incorporating hourly reminder bells. The results were quite impressive in improved Incentive Spirometer use adherence, atelectasis severity, early postoperative fevers, noninvasive positive pressure ventilation use, intensive care unit length of stay by a day, and 6-month mortality rates.

“Incentive spirometers can be clinically effective, but perhaps only when adherence is high”. Further studies are recommended on incentive spirometry without reminders. As a relatively small trial, further larger studies with balanced patient populations are essential.

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Second Generation Drug Eluting Stents and Surgery

Non-cardiac elective surgery after placement of coronary stents is performed after time guidelines delineated previously (eg. link ).

Second generation drug eluting stents were reviewed in medical records in this study. The rates of major adverse cardiac events were 17.1%, 10.0%, 0.0%, and 3.1% for patients undergoing non-cardiac surgery at 0–90, 91–180, 181–365, and ≥366 days, respectively. 

The rate of excessive surgical bleeding was 6.7% with the highest observed rate in those on dual antiplatelet therapy although not statistically significant compared to those not receiving dual antiplatelet therapy in the 7 days before surgery, although numbers were small.

The important takeaway is that 180 days (6 months) is still a reasonable minimum before elective non-cardiac surgery for those on dual antiplatelet therapy.

Full details are discussed, along with comparisons to various guidelines at the link.

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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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