Microbubbles detection during cardiopulmonary bypass with transoesophageal echocardiography: a case report

Microemboli induced by air bubbles may be deposited in organs as a consequence of contamination during medical care

Background

Larger volumes of accidental air infused during medical care may end up as emboli while microbubbles of air are supposed to be absorbed and cause no harm. The aim of this autopsy study was to investigate if microbubbles of air accidently entering the bloodline may be detected as microemboli (ME) in tissue such as lungs, brain and heart. If so, do differences in prevalence exist between haemodialysis (HD) and amyotrophic lateral sclerosis (ALS) patients.

Methods

Included were data from 44 patients treated by medical healthcare before death. Twenty-five cases had been treated with chronic HD and 19 cases died from ALS. Since air in the bloodline activates coagulation, ME could appear. To discriminate between microbubbles caused by artificial contamination during autopsy versus microbubbles deposited in vivo, tissues were stained with a polyclonal fluorescent antibody against fibrinogen, fibrin and fragments E and D. Fluorescence staining was used to visualize ME counted within 25 microscopic fields (600×) of a tissue preparation. One tissue preparation was used if available from the lung, heart and frontal lobe of the brain and in five cases also the cerebellum.

Results

Microbubbles can be verified at autopsy as ME in the lung, heart and brain in tissue from patients exposed to more extensive medical care. There were significantly more ME in the lungs versus the heart or brain. Women had fewer ME than men. The HD group had a higher median of ME per section than the ALS group (lung: 6 versus 3, P = .007; heart: 2.5 versus 1, P = .013; brain: 7.5 versus 2, P = .001) and had more sections with ME findings than the ALS group (P = .002). A correlation existed between the time on HD (months) and ME in the lungs.

Conclusions

More ME were present in HD patients compared with those who suffered from ALS. Minimizing air contamination from syringes, infusions and bloodlines will decrease ME and subsequent tissue injury.

Brain emboli distribution and differentiation during cardiopulmonary bypass

OBJECTIVE

Cardiopulmonary bypass (CPB) is a lifesaving practice in cardiac surgery, but its use frequently is associated with cerebral injury and neurocognitive dysfunctions. Despite the involvement of numerous factors, microembolism occurring during CPB seems to be one of the main mechanisms leading to such alterations. The aim of the present study was to characterize the occurrence of cerebral microembolism with reference to microembolic amount, nature, and distribution in different combinations of cardiac procedures and CPB on the microembolic load.

DESIGN

A retrospective observational clinical study.

SETTING

A single-center regional hospital.

PARTICIPANTS

Fifty-five patients undergoing elective cardiac surgery with CPB.

INTERVENTIONS

Bilateral detection of the patients' middle cerebral arteries using a multifrequency transcranial Doppler.

MEASUREMENTS AND MAIN RESULTS

Patients were divided into 3 groups depending on the CPB circuit used (open, open with vacuum, or closed). There was a significant difference between the number of solid and gaseous microemboli (p<0.001), with the solid lower than the gaseous ones. The number of solid microemboli was affected by group (p< 0.05), CPB phase (p<0.001), and laterality (p<0.01). The number of gaseous microemboli was affected only by group (p<0.05) and CPB phase (p<0.001). Generally, the length of CPB phase did not affect the number of microemboli.

CONCLUSIONS

Surgical procedures combined with CPB circuits, but not the CPB phase length, affected the occurrence, nature, and laterality of microemboli.

Multimodal brain monitoring reduces major neurologic complications in cardiac surgery

OBJECTIVE

Although adverse neurologic outcomes are common complications of cardiac surgery, intraoperative brain monitoring has not received adequate attention. The aim of the present study was to evaluate the effectiveness of multimodal brain monitoring in the prevention of major brain injury and reducing the duration of mechanical ventilation, intensive care unit, and postoperative hospital stays after cardiac surgery.

DESIGN

A retrospective, observational, controlled study.

SETTING

A single-center regional hospital.

PARTICIPANTS

One thousand seven hundred twenty-one patients who had undergone cardiac surgery with cardiopulmonary bypass from July 2007 to July 2010. One hundred sixty-six patients with multimodal brain monitoring and a control group without brain monitoring (N = 1,555) were compared retrospectively.

INTERVENTIONS

Multimodal brain monitoring was performed for 166 patients, consisting of intraoperative recordings of somatosensory-evoked potentials, electroencephalography, and transcranial Doppler.

MEASUREMENTS AND MAIN RESULTS

The incidence of major neurologic complications and the duration of mechanical ventilation, intensive care unit, and postoperative hospital stays were considered. Patients with brain monitoring had a significantly lower incidence of perioperative major neurologic complications (0%) than those without monitoring (4.06%, p = 0.01) and required significantly shorter periods of mechanical ventilation (p = 0.001) and intensive care unit stays (p = 0.01) than controls. The length of postoperative hospital stays did not differ significantly between the 2 groups (p = 0.57).

CONCLUSIONS

This preliminary study suggests that multimodal brain monitoring can reduce the incidence of neurologic complications as well as hospital costs associated with post-cardiac surgery patient care. Furthermore, intraoperative brain monitoring provides useful information about brain functioning, blood flow velocity, and metabolism, which may guide the anesthesiologist during surgery.