Cardiopulmonary bypass

Guidelines Issued for Managing Temperature During CBP

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For the first time ever, clinical practice guidelines on managing patient temperature during cardiopulmonary bypass (CPB) surgery have been published, appearing in the Annals of Thoracic Surgery.

The guidelines were jointly issued by the Society of Thoracic Surgeons, theSociety of Cardiovascular Anesthesiologists, and the American Society of ExtraCorporeal Technology.

“Numerous strategies are currently invoked by perfusion teams to manage the requirements of cooling, temperature maintenance, and rewarming patients during cardiac surgical procedures. To date there have been very few evidence-based recommendations for the conduct of temperature management during perfusion,” according to the guideline authors, led by Richard Engelman, MD, of Baystate Medical Center in Springfield, Mass.

“Basically we are trying to protect the brain,” Engelman told MedPage Today. “The rest of the body can deal fairly well with heat and cold, but the brain is the most adversely affected by temperature, especially overheating. So we have detailed an approach during the conduct of cardiopulmonary bypass to prevent overheating and potential injury to the brain.”

Engelman and colleagues reviewed 615 abstracts and 153 full papers published between 2000 and 2014 to come up with recommendations in four areas: the optimal site for temperature monitoring, avoidance of hyperthermia, peak cooling temperature gradient and cooling rate, and peak warming temperature gradient and warming rate. The authors made the following recommendations:

Class I Recommendations:

  • The oxygenator arterial outlet blood temperature should be utilized as a surrogate for cerebral temperature measurement during CPB.
  • To monitor cerebral perfusate temperature during warming, it should be assumed that the oxygenator arterial outlet blood temperature underestimates cerebral perfusate temperature.
  • Surgical teams should limit arterial outlet blood temperature to <37 degrees C to avoid cerebral hyperthermia.
  • Temperature gradients between the arterial outlet and venous inflow on the oxygenator during CPB cooling should not exceed 10 degrees C to avoid generation of gaseous emboli.
  • Temperature gradients between the arterial outlet and venous inflow on the oxygenator during CPB rewarming should not exceed 10 degrees C to avoid outgassing when blood is returned to the patient.

Class IIa Recommendations:

  • Pulmonary artery or nasopharyngeal temperature recording is reasonable for weaning and immediate post-bypass temperature measurement.
  • To achieve the desired temperature for separation from bypass when arterial blood outlet temperature ≥30 degrees C, it is reasonable to maintain a temperature gradient between arterial outlet temperature and the venous inflow of ≤4 degrees C; and also to maintain a rewarming rate ≤0.5 degrees C/min.
  • To achieve the desired temperature for separation from bypass when arterial blood outlet temperature <30 degrees C, it is reasonable to maintain a maximal gradient of 10 degrees C between arterial outlet temperature and venous inflow.

The authors made no specific recommendation for an optimal temperature for weaning from CPB “due to inconsistent published evidence.”

“Our new guidelines will help improve understanding of the relationship between temperature management and clinical outcomes, particularly its impact on brain function,” Engelman said in a press release. “The guidelines also will increase patient awareness about the issue and help begin a dialogue between the patient and the cardiothoracic surgical team prior to surgery.”

“We would like to make patients part of the discussion,” Engelman toldMedPage Today. “For example, a patient might ask, ‘Will you be following an appropriate guideline for managing my body temperature to avoid potential brain injury?'”

Engelman and colleagues are working on two other sets of guidelines which may be published next year. One is on reducing the inflammation associated with use of a heart-lung machine to avoid complications related to blood utilization and reduce the need for transfusions. The other details the optimal devices to use within a heart-lung machine for measuring blood temperature and flow.

UK first in heart failure operation.

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Sevket Gocer,
Sevket Gocer, right, was the first patient in the UK

A pioneering operation to improve the function of failing hearts while they are still beating has taken place in the UK for the first time.

Patients with heart failure struggle to pump blood around the body and mild exercise can leave them breathless.

Surgeons used a form of “cardiac sewing” to remove scar tissue and reduce the size of the heart so it pumps more efficiently.

The operation took place at King’s College Hospital in London.

One common cause of heart failure is when the arteries which nourish the organ become blocked, leading to a heart attack. Heart muscle dies and is replaced by hard scar tissue which does not beat.

Over time, the scar tissue can stretch so chambers of the heart become larger, meaning the organ has more blood to force out with each heartbeat.

The overall effect is a weaker heart, less able to do its job, transforming simple day-to-day tasks like climbing stairs into extreme exertions.

In the operation, surgeons used a wire with anchors at both ends to pierce two sections of heart muscle. When the wire was tightened, the walls of the heart were “remodelled”.

Before and after surgery
Scar tissue, in grey, is “sewn out”

The scar tissue was effectively removed and the volume of one of the chambers of the heart was reduced by a quarter.

Sevket Gocer, 58 and from Bromley in south-east London, was the first patient to be treated in the UK. His heart function is said to have “improved significantly” after the operation.

A similar procedure used to be performed by opening up the chest and stopping the heart, but it was a very risky operation and fell out of medical practice.

Surgeons hope the less invasive operation, which can be performed while the heart is still pumping, will be a better option for patients.

Mr Olaf Wendler, a professor of cardiac surgery at King’s College Hospital, told the BBC: “In the technique we have now used for the first time in the UK, one does not need to stop the heart, one does not even necessarily need to place the patient on a heart-lung machine.

“It’s a less traumatic and less invasive type of procedure.”

He said the operation was being tested in a trial at hospitals across Europe and that the procedure could make a difference to patients’ lives.

He said: “[If successful] it’s bringing them on to an exercise level where they’re able to look after themselves properly including going to do the shopping and having a social life.”

Prof Jeremy Pearson, associate medical director at the British Heart Foundation, said: “The results of this trial will determine if this experimental procedure is safe.

“If the trial is successful, there will be further use of the technology as surgeons gain expertise in the technique. As more people are treated with this procedure, it will become fully clear whether it will have a real benefit for patients.”

Hydroxyethyl Starch Solutions Get Boxed Warning.

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Hydroxyethyl starch solutions should not be used in critically ill patients, including those with sepsis and those admitted to the ICU, because they pose an increased risk for mortality and severe renal injury, the FDA has announced. A boxed warning will be added to the solutions’ labels to emphasize these risks.

Providers are also advised to avoid using HES solutions in patients with preexisting renal dysfunction. Treatment should be stopped at the first sign of renal injury; renal function should be monitored in all patients for 90 days after treatment.

In addition, the FDA says, HES solutions should be avoided in patients undergoing open heart surgery in association with cardiopulmonary bypass, given an increased risk for excessive bleeding. A separate warning about this risk will be added to the Warnings and Precautions section of the label.

Source: FDA

 

Featured in Journal Watch: More Studies from the San Francisco Cardiology Sessions.

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Journal Watch Cardiology summarizes three New England Journal of Medicine studies that were presented at the American College of Cardiology conference:

Nonemergency PCI seems safe to perform at hospitals without on-site cardiac surgery facilities, according to a randomized study that included some 3700 patients. Three fourths underwent PCI at hospitals without on-site cardiac surgery, and the rest were transferred to hospitals with on-site facilities. The rate of a composite outcome (death, MI, repeat revascularization, or stroke) did not differ between the groups at either 30 days or 12 months.

In two studies of relatively high-risk patients undergoing CABG, use or nonuse of cardiopulmonary bypass had no significant effect on the rate of composite outcomes that included death, MI, stroke, repeat revascularization, or renal failure. Joel M. Gore comments that the choice regarding cardiopulmonary bypass “thus depends chiefly on operator expertise and individual patient characteristics and preferences.”

Source: Journal Watch Cardiology