Subcutaneous tissue oxygen tension after coronary revascularisation with and without cardiopulmonary bypass

Quantitative Image Quality Comparison of Reduced- and Standard-Dose Dual-Energy Multiphase Chest, Abdomen, and Pelvis CT

We present a new image quality assessment method for determining whether reducing radiation dose impairs the image quality of computed tomography (CT) in qualitative and quantitative clinical analyses tasks. In this Institutional Review Board-exempt study, we conducted a review of 50 patients (male, 22; female, 28) who underwent reduced-dose CT scanning on the first follow-up after standard-dose multiphase CT scanning. Scans were for surveillance of von Hippel–Lindau disease (N = 26) and renal cell carcinoma (N = 10). We investigated density, morphometric, and structural differences between scans both at tissue (fat, bone) and organ levels (liver, heart, spleen, lung). To quantify structural variations caused by image quality differences, we propose using the following metrics: dice similarity coefficient, structural similarity index, Hausdorff distance, gradient magnitude similarity deviation, and weighted spectral distance. Pearson correlation coefficient and Welch 2-sample t test were used for quantitative comparisons of organ morphometry and to compare density distribution of tissue, respectively. For qualitative evaluation, 2-sided Kendall Tau test was used to assess agreement among readers. Both qualitative and quantitative evaluations were designed to examine significance of image differences for clinical tasks. Qualitative judgment served as an overall assessment, whereas detailed quantifications on structural consistency, intensity homogeneity, and texture similarity revealed more accurate and global difference estimations. Qualitative and quantitative results indicated no significant image quality degradation. Our study concludes that low(er)-dose CT scans can be routinely used because of no significant loss in quantitative image information compared with standard-dose CT scans.

Direct oxymetric peripheral tissue perfusion monitoring during open heart surgery with the use of cardiopulmonary bypass: preliminary experience

BACKGROUND

Regional hypoperfusion has been associated with the development of postoperative organ dysfunction in cardiac surgery involving cardiopulmonary bypass (CPB). Direct tissue oxymetry is a potentially new method for monitoring the quality of the peripheral tissue perfusion during CPB. The aim of this study was to assess the effects of CPB in skeletal muscle oxygenation when measured in the deltoid muscle by direct oxymetry during perioperative period.

METHOD

Seven patients underwent on-pump coronary artery bypass grafting. Direct oxymetry was performed by an optical cathether introduced into the deltoid muscle. Continuous measurement was made during the surgical procedure and the postoperative period. Mean arterial blood pressure, blood flow during CPB, laboratory markers of tissue hypoperfusion, blood gases and body temperature were also recorded.

RESULTS

Interstitial muscle tissue oxygen tension (pO(2)) decreased after the introduction to anaesthesia and, more significantly, during CPB. After the disconnection from CPB at the end of the operation, the pO(2) returned to pre-anaesthetic values. During the first hours after admission of the patients to the intensive care unit, the pO(2) progressively decreased, reached a minimum value after four hours, and increased slowly thereafter. There was a significant correlation of pO(2) with mean arterial blood pressure and blood flow during that time.

CONCLUSION

The result of this first measurement seems to demonstrate that the standard technique of conducting cardiopulmonary bypass produces low muscle oxygen tension and, thus, little perfusion of skeletal muscle. The data also indicate that both high mean arterial blood pressure and high flow are necessary during CPB to ensure skeletal muscle perfusion. The investigation is continuing.

Considerations in prevention of surgical site infections following cardiac surgery: when your patient is diabetic

The incidence of surgical site infections among patients with diabetes continues to occur at a greater rate when compared with their nondiabetic counterparts. Preexisting vascular changes, delayed wound healing, and impaired immune factors contribute. Adult patients with diabetes likely possess comorbid coronary artery disease, thus increasing the need for cardiac surgery. The resultant potential for infection can be combated with supplementary interventions above those universally taken. Modifiable risk factors of hyperglycemia and obesity are targeted preoperatively. Glycemic control, adequate tissue perfusion, and adjunct use of nasal mupirocin are addressed intraoperatively. Lastly, focus is placed on nutrition, exercise, and continued glucose control postoperatively and beyond discharge.

Modulation of systemic inflammatory response after cardiac surgery

Cardiac surgery and cardiopulmonary bypass initiate a systemic inflammatory response largely determined by blood contact with foreign surfaces and the activation of complement. It is generally accepted that cardiopulmonary bypass initiates a whole-body inflammatory reaction. The magnitude of this inflammatory reaction varies, but the persistence of any degree of inflammation may be considered potentially harmful to the cardiac patient. The development of strategies to control the inflammatory response following cardiac surgery is currently the focus of considerable research efforts. Diverse techniques including maintenance of hemodynamic stability, minimization of exposure to cardiopulmonary bypass circuitry, and pharmacologic and immunomodulatory agents have been examined in clinical studies. This article briefly reviews the current concepts of the systemic inflammatory response following cardiac surgery, and the various therapeutic strategies being used to modulate this response.

Sternal wound complications in bilateral internal thoracic artery grafting: a comparison of the off-pump technique and conventional cardiopulmonary bypass

BACKGROUND

Sternal wound complication is a major concern in bilateral internal thoracic artery grafting. The purpose of this study was to assess whether avoiding cardiopulmonary bypass has beneficial effects with fewer wound complications in patients receiving bilateral internal thoracic artery grafting.

METHODS

Retrospective review was performed using prospectively gathered data of 69 patients who had undergone elective coronary artery bypass grafting and received conventional pedicled bilateral internal thoracic artery grafting from December 2002 through April 2004 by the same surgical team. The patients were divided into 2 groups: those who underwent coronary artery bypass grafting without cardiopulmonary bypass (off-pump group, n = 41), and those who underwent coronary artery bypass grafting with cardiopulmonary bypass (CPB group, n = 28). Chart review and 3-month follow-up were obtained for all patients. These 2 groups were compared for sternal wound complications and preoperative, intraoperative, and postoperative variables.

RESULTS

Deep sternal wound infection (SWI) was seen in 1 patient (2.4%), superficial SWI in 2 patients (4.8%), and sternal dehiscence in 1 patient (2.4%) in the off-pump group. Deep SWI was seen in no patients, superficial SWI in 2 patients (7.1%) and sternal dehiscence in 2 patients (7.1%) in the CPB group. No statistically significant difference in the frequency of occurrence of sternal complications was detected between the 2 study groups.

CONCLUSIONS

The results suggest that the avoidance of CPB has no beneficial effect on the number of sternal wound complications in patients receiving bilateral internal thoracic artery grafting. However, further prospective, randomized studies on large patient groups are required to assess this finding.