Prevention of Aortic Dissection Suggests a Diameter Shift to a Lower Aortic Size Threshold for Intervention.

BACKGROUND: Multiple studies have quantified the relationship between aortic size and risk of dissection. However, these studies estimated the risk of dissection without accounting for any increase in aortic size from the dissection process itself. OBJECTIVES: This study aims to compare aortic size before and after dissection and to evaluate the change in size consequent to the dissection itself. METHODS: Fifty-five consecutive patients (29 type A; 26 type B) with aortic dissection and incidental imaging studies prior to dissection were identified and compared to a control group of aneurysm patients (n = 205). The average time between measurement at and prior to dissection was 1.7 ± 1.9 years (1.9 ± 2.0 years mean inter-image time in the control group). A multivariate regression model controlling for growth rate, age, and gender was created to estimate the effect of dissection itself on aortic size. RESULTS: The mean aortic sizes at and prior to dissection were 54.2 ± 7.0 and 45.1 ± 5.7 mm for the ascending aorta, and 47.1 ± 13.8 and 39.5 ± 13.1 mm for the descending aorta, respectively. The multivariable analysis revealed a significant impact of the dissection itself (p < 0.001) and estimated an increase in size of 7.65 mm (ascending aorta) and 6.38 mm (descending aorta). Thus, a proportional estimate of 82.8% (ascending aorta) and 80.8% (descending aorta) of dissections are made at a size lower than the guideline-recommended threshold (55 mm). CONCLUSIONS: The aortic diameter increases substantially due to aortic dissection itself and, thus, aortas are being dissected at clinically meaningfully smaller sizes than natural history analyses have previously suggested. These findings have important implications regarding the size at which the risk of dissection is increased.

Cognitive and functional status predictors of delirium and delirium severity after coronary artery bypass graft surgery: an interim analysis of the Neuropsychiatric Outcomes After Heart Surgery study.

BACKGROUND: Cognitive and functional impairment increase risk for post-coronary artery bypass graft (CABG) surgery delirium (PCD), but how much impairment is necessary to increase PCD risk remains unclear. METHODS: The Neuropsychiatric Outcomes After Heart Surgery (NOAHS) study is a prospective, observational cohort study of participants undergoing elective CABG surgery. Pre-operative cognitive and functional status based on Clinical Dementia Rating (CDR) scale and neuropsychological battery are assessed. We defined mild cognitive impairment (MCI) based on either (1) CDR global score 0.5 (CDR-MCI) or (2) performance 1.5 SD below population means on any cognitive domain on neurocognitive battery (MCI-NC). Delirium was assessed daily post-operative day 2 through discharge using the confusion assessment method (CAM) and delirium index (DI). We investigate whether MCI - either definition - predicts delirium or delirium severity. RESULTS: So far we have assessed 102 participants (mean age 65.1 ± 9; male: 75%) for PCD. Twenty six participants (25%) have MCI-CDR; 38 (62% of those completing neurocognitive testing) met MCI-NC criteria. Fourteen participants (14%) developed PCD. After adjusting for age, sex, comorbidity, and education, MCI-CDR, MMSE, and Lawton IADL score predicted PCD on logistic regression (OR: 5.6, 0.6, and 1.5, respectively); MCI-NC did not (OR [95% CI]: 11.8 [0.9, 151.4]). Using similarly adjusted linear regression, MCI-CDR, MCI-NC, CDR sum of boxes, MMSE, and Lawton IADL score predicted delirium severity (adjusted R(2): 0.26, 0.13, 0.21, 0.18, and 0.32, respectively). CONCLUSIONS: MCI predicts post-operative delirium and delirium severity, but MCI definition alters these relationships. Cognitive and functional impairment independently predict post-operative delirium and delirium severity.

Elective surgery for ascending aortic aneurysm in the elderly: should there be an age cut-off?

OBJECTIVES: The objective of this study is to retrospectively analyse surgical outcomes in patients aged 75-79, and 80 and above. METHODS: Between 2000 and 2015, 108 patients aged 75-79 (G 75 , mean age 76.9 ± 1.5years) and 72 patients aged 80 and above (G 80 , mean age 82.2 ± 2.1years) underwent elective aneurysm repair. Operative outcome and survival was compared with 727 contemporary younger counterparts aged <75 years (G Ctrl , mean age 56.6 ± 11.7years). RESULTS: Postoperatively, patients with advanced age showed a higher incidence of prolonged ventilation (G 80 21.4%, G 75 8.4%, G Ctrl 2.9%; P < 0.001), low cardiac output syndrome (G 80 11.4%, G 75 1.9%, G Ctrl 2.2%; P = 0.001), multi organ failure (G 80 2.9%, G 75 0%, G Ctrl 0.1%; P = 0.022), haemofiltration (G 80 8.6%, G 75 0.9%, G Ctrl 0.6%; P < 0.001), and infection (G 80 10.0%, G 75 6.5%, G Ctrl 3.5%; P = 0.017). Operative mortality was significantly increased in the elderly (G 80 11.1%, G 75 3.7%, G Ctrl 1.4%; P < 0.001). Mid-term survival differed significantly between the surgical groups. Multivariate regression analysis precluded age as an independent predictor of operative mortality. CONCLUSIONS: Elderly patients showed a higher operative risk compared to their younger counterparts. However, age per se is no suitable indicator of surgical risk and well-selected patients with large threatening aneurysms may benefit from intervention.

Can Transcutaneous CO2 Tension Be Used to Calculate Ventilatory Dead Space? A Pilot Study.

Dead space fraction (V d/V t) measurement performed using volumetric capnography requires arterial blood gas (ABG) sampling to estimate the partial pressure of carbon dioxide (PaCO2). In recent years, transcutaneous capnography (PtcCO2) has emerged as a noninvasive method of estimating PaCO2. We hypothesized that PtcCO2 can be used as a substitute for PaCO2 in the calculation of V d/V t. In this prospective pilot comparison study, 30 consecutive postcardiac surgery mechanically ventilated patients had V d/V t calculated separately using volumetric capnography by substituting PtcCO2 for PaCO2. The mean V d/V t calculated using PaCO2 and PtcCO2 was 0.48 ± 0.09 and 0.53 ± 0.08, respectively, with a strong positive correlation between the two methods of calculation (Pearson's correlation = 0.87, p < 0.05). Bland-Altman analysis showed a mean difference of -0.05 (95% CI: -0.01 to -0.09) between the two methods. PtcCO2 measurements can provide a noninvasive means to measure V d/V t, thus accessing important physiologic information and prognostic assessment in patients receiving mechanical ventilation.