Efficacy of Carbon Dioxide Insufflation for Cerebral and Cardiac Protection During Open Heart Surgery: A Systematic Review and Meta-Analysis

Optimizing CO2 field flooding during sternotomy: In vitro confirmation of the Karolinska studies

Although CO2 field-flooding was first used during cardiac surgery more than 60 years ago, its efficacy is still disputed. The invisible nature of the gas and the difficulty in determining the "safe" quantity to protect the patient are two of the main obstacles to overcome for its validation. Moreover, CO2 concentration in the chest cavity is highly sensitive to procedural aspects, such suction and hand movements. Based on our review of the existing literature, we identified four major factors that influence the intra-cavity CO2 concentration during open-heart surgery: type of delivery device (diffuser), delivery CO2 flow rate, diffuser position around the wound cavity, and its orientation inside the cavity. In this initial study, only steady state conditions were considered to establish a basic understanding on the effect of the four above-mentioned factors. Transient factors, such as suction or hand movements, will be reported separately.

Development of a Gastight Thoracotomy Model for Investigation of Carbon Dioxide Field-Flooding Efficacy

Carbon dioxide (CO₂) field-flooding during cardiac surgery is a prevention technique to avoid blood-air contact and subsequent embolization. Although it was first used more than 60 years ago, there is still some perplexity around its efficacy, mainly because the gas is invisible and air embolization is difficult to quantify.

An accurate assessment of field-flooding can, therefore, best be performed in models where various methods can be tried in a controlled environment and evaluated with industrial-grade sensors. Multiple options are available for anatomically correct models that reproduce a sternotomy situation, but models for minimally invasive cardiac surgery are expensive and normally meant for training of surgical techniques where only the top side of the model is important.

We created a low-cost and “home-made” gastight mini-thoracotomy model with internal organs and left atrial incision to investigate CO₂ insufflation in a simulated minimally invasive mitral valve surgery. The model was validated with CO₂ field-flooding tests with a commercial diffuser, while three sensors continuously registered the local concentration of CO₂ gas.

Effects of carbon dioxide insufflation on anastomosis remodeling at a carotid artery site in rabbits

Introduction

Use of carbon dioxide (CO₂) insufflation (CDI) on the surgical field during heart surgery has become widespread, and in some units routine.

Aim

To assess the effects of CDI on endothelial dysfunction in a carotid artery model in rabbits.

Material and methods

Twelve randomly selected rabbits were divided into two groups. Right carotid arteries of the animals were transected and sutured with running suture technique. Then, 1 l/min CO₂ insufflation was initiated with a 45° angle. In the control group, the anastomotic field was irrigated with 0.1 ml/s flow of 0.9% saline. At day 28, the carotid artery segments were removed and prepared for histological specimens.

Results

In the cross-sections of the control group vessel samples, thickening of the tunica intima was observed. Scoring the quantity of endothelial nitric oxide synthase (e-NOS) and α-smooth muscle actin (α-SMA) positive staining revealed a nonsignificant difference between the experimental groups (p = 0.07). In the CO₂ group, the intimal hyperplasia (p = 0.2) and the thickness of the tunica media (p = 0.2) were indistinguishable when compared to the control group. The mean luminal diameters and luminal areas of the experimental groups were all evaluated by histomorphometry and a significant differences was found between luminal areas (p = 0.016). On the other hand, no significant difference was found between mean luminal diameters (p = 0.055).

Conclusions

Our study indicated that CDI can affect endothelial cell damage and the mean luminal diameters.

The influence of carbon dioxide field flooding in mitral valve operations with cardiopulmonary bypass on S100ß level in blood plasma in the aging brain

Introduction

The risk of air microembolism during cardiopulmonary bypass (CPB) is high and influences the postoperative outcome, especially in elderly patients. The use of carbon dioxide (CO₂) atmosphere during cardiac surgery may reduce the risk of cerebral air microembolism. The aim of our study was to assess the influence of CO₂ field flooding on microembolism-induced brain damage assessed by the level of S100ß protein, regarded as a marker of brain damage.

Materials and methods

A group of 100 patients undergoing planned mitral valve operation through median sternotomy using standard CPB was recruited for the study. Echocardiography was performed prior to and after the CPB. CO₂ insufflation at 6 L/minute was conducted in the study group. Blood samples for S100ß protein analysis were collected after induction of anesthesia, 2 hours after aorta de-clamping, and 24 hours after operation.

Results

The S100ß level in blood plasma did not differ significantly between the study and the control group (0.13±0.08 µg/L, 1.12±0.59 µg/L, and 0.26±0.23 µg/L and 0.18±0.19 µg/L, 1.31±0.62 µg/L, and 0.23±0.12 µg/L, P=0.7, 0.14, and 0.78). The mean increase of the S100ß concentration was 13% lower in the group with CO₂ protection than in the control group (0.988 µg/L vs 1.125 µg/L), although statistically insignificant. Tricuspid valve annuloplasties (TVAs) had significant impact on the increase in S100ß concentration in the treatment group after 24 hours (TVA [−] 0.21±0.09 vs TVA [+] 0.42±0.42, P=0.05). In patients <60 years, there were significant differences in the S100ß level 2 and 24 hours after the procedure (1.59±0.682 µg/L vs 1.223±0.571 µg/L, P=0.048, and 0.363±0.318 µg/L vs 0.229±0.105 µg/L, P=0.036) as compared with younger patients.

Conclusion

The increase in S100ß concentration was lower in the group with CO₂ protection than in the control group. Age and an addition of TVA significantly influenced the level of S100ß concentration in the tests performed 2 hours after aortic clamp release.

Pulmonary collapse alone provides effective de-airing in cardiac surgery: a prospective randomized study

OBJECTIVES

We previously described and showed that the method for cardiac de-airing involving: (1) bilateral, induced pulmonary collapse by opening both pleurae and disconnecting the ventilator before cardioplegic arrest and (2) gradual pulmonary perfusion and ventilation after cardioplegic arrest is superior to conventional de-airing methods, including carbon dioxide insufflation of the open mediastinum. This study investigated whether one or both components of this method are responsible for the effective de-airing of the heart.

METHODS

Twenty patients scheduled for open, left heart surgery were randomized to two de-airing techniques: (1) open pleurae, collapsed lungs and conventional pulmonary perfusion and ventilation; and (2) intact pleurae, expanded lungs and gradual pulmonary perfusion and ventilation.

RESULTS

The number of cerebral microemboli measured by transcranial Doppler sonography was lower in patients with open pleurae 9 (6-36) vs 65 (36-210), p = 0.004. Residual intra-cardiac air grade I or higher as monitored by transesophageal echocardiography 4-6 minutes after weaning from cardiopulmonary bypass was seen in few patients with open pleurae 0 (0%) vs 7 (70%), p = 0.002.

CONCLUSIONS

Bilateral, induced pulmonary collapse alone is the key factor for quick and effective de-airing of the heart. Gradual pulmonary perfusion and ventilation, on the other hand, appears to be less important.

Artificial Organs 2013: a year in review

In this Editor's Review, articles published in 2013 are organized by category and briefly summarized. We aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ Replacement, Recovery, and Regeneration. As the official journal of The International Federation for Artificial Organs, The International Faculty for Artificial Organs, the International Society for Rotary Blood Pumps, the International Society for Pediatric Mechanical Cardiopulmonary Support, and the Vienna International Workshop on Functional Electrical Stimulation, Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level". Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ Replacement, Recovery, and Regeneration from all over the world. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide so meaningful suggestions to the author's work whether eventually accepted or rejected and especially to those whose native tongue is not English. Without these excellent and dedicated reviewers the quality expected from such a journal could not be possible. We also express our special thanks to our Publisher, Wiley Periodicals, for their expert attention and support in the production and marketing of Artificial Organs. We look forward to recording further advances in the coming years.