Ex Vivo Comparison of the Elastic Properties of Vascular Substitutes Used for Pulmonary Artery Replacement.

INTRODUCTION: Study aims were to evaluate the elastic properties of vascular substitutes frequently used for pulmonary artery (PA) replacement, and then to compare their compliance and stiffness indexes to those of human PA. METHODS: A bench-test pulsatile flow experiment was developed to perfuse human cadaveric vascular substitutes (PA, thoracic aorta, human pericardial conduit), bovine pericardial conduit, and prosthetic vascular substitutes (polytetrafluorethylene and Dacron grafts) at a flow and low pulsed pressure mimicking pulmonary circulation. Intraluminal pressure was measured. An ultrasound system with an echo-tracking function was used to monitor vessel wall movements. The diameter, compliance, and stiffness index were calculated for each vascular substitute and compared to the human PA at mean pressures ranging from 10 to 50 mmHg. RESULTS: The compliance of the PA and the thoracic aorta were similar at mean physiological pressures of 10 mmHg and 20 mmHg. The PA was significantly less compliant than the aorta at mean pressures above 30 mmHg (P = 0.017). However, there was no difference in stiffness index between the two substitutes over the entire pressure range. Compared to the PA, human pericardial conduit was less compliant at 10 mmHg (P = 0.033) and stiffer at 10 mmHg (P = 0.00038) and 20 mmHg (P = 0.026). Bovine pericardial conduit and synthetic prostheses were significantly less compliant and stiffer than the PA for mean pressures of 10, 20, and 30 mmHg. There were no differences at 40 and 50 mmHg. CONCLUSIONS: Allogenic arterial grafts appear to be the most suitable vascular substitutes in terms of compliance and stiffness for PA replacement.

Assessment of abdominal branch vessel patency after bare-metal stenting of the thoracoabdominal aorta in a human ex vivo model of acute type B aortic dissection.

OBJECTIVE: The purpose of this study was to assess the efficiency of bare-metal stenting of the thoracoabdominal aorta in a human ex vivo model of acute type B aortic dissection and the impact of this approach on the patency of the visceral and renal arteries. METHODS: Fifteen human cadaveric aortas were harvested. Type B aortic dissections were surgically initiated 2 cm below the left subclavian artery. Aortas were thereafter connected to a bench top pulsatile flow to induce propagation of the dissection. A 5-mm 30° lens (Richard Wolf, Vernon Hills, Ill) was introduced successively into the false lumen and the true lumen to monitor the propagation of the dissection. Bare-metal stents were deployed into the true lumen from the primary entry tear to the infrarenal aorta. Measurement of systolic pressure was taken within the abdominal branch vessels before and after stenting. A pressure gradient drop of 15 mm Hg or more after bare-metal stenting was considered hemodynamically relevant. RESULTS: Dissection was propagated at least to the renal aorta in 11 cases (73%) and to the infrarenal aorta in 3 cases (20%). Of the 60 abdominal branch vessels studied, 22 (36.7%) were supplied by the false lumen. After extensive aortic bare-metal stenting, complete reattachment of the dissection flap was observed in all cases. Regarding visceral and renal artery patency after bare-metal stenting, a significant pressure gradient drop was reported in 54.5% (n = 12) when these arteries were supplied by the false lumen, whereas those originating from the true lumen had a significantly less common pressure gradient drop (7.9% [n = 3]; P < .0001). CONCLUSIONS: Bare-metal stenting in this model of acute type B aortic dissection was effective in true lumen reexpansion but induced a high (54.5%) rate of significant pressure drop in the visceral and renal arteries when they were supplied by the false lumen.

Patient-ventilator synchrony in Neurally Adjusted Ventilatory Assist (NAVA) and Pressure Support Ventilation (PSV): a prospective observational study.

BACKGROUND: Weaning from mechanical ventilation is associated with the presence of asynchronies between the patient and the ventilator. The main objective of the present study was to demonstrate a decrease in the total number of patient-ventilator asynchronies in invasively ventilated patients for whom difficulty in weaning is expected by comparing neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) ventilatory modes. METHODS: We performed a prospective, non-randomized, non-interventional, single-center study. Thirty patients were included in the study. Each patient included in the study benefited in an unpredictable way from both modes of ventilation, NAVA or PSV. Patients were successively ventilated for 23 h in NAVA or in PSV, and then they were ventilated for another 23 h in the other mode. Demographic, biological and ventilatory data were collected during this period. The two modes of ventilatory support were compared using the non-parametric Wilcoxon test after checking for normal distribution by the Kolmogorov-Smirnov test. The groups were compared using the chi-square test. RESULTS: The median level of support was 12.5 cmH2O (4-20 cmH2O) in PSV and 0.8 cmH2O/µvolts (0.2-3 cmH2O/µvolts) in NAVA. The total number of asynchronies per minute in NAVA was lower than that in PSV (0.46 vs 1, p < 0.001). The asynchrony index was also reduced in NAVA compared with PSV (1.73 vs 3.36, p < 0.001). In NAVA, the percentage of ineffective efforts (0.77 vs 0.94, p = 0.036) and the percentage of auto-triggering were lower compared with PSV (0.19 vs 0.71, p = 0.038). However, there was a higher percentage of double triggering in NAVA compared with PSV (0.76 vs 0.71, p = 0.046). CONCLUSION: The total number of asynchronies in NAVA is lower than that in PSV. This finding reflects improved patient-ventilator interaction in NAVA compared with the PSV mode, which is consistent with previous studies. Our study is the first to analyze patient-ventilator asynchronies in NAVA and PSV on such an important duration. The decrease in the number of asynchronies in NAVA is due to reduced ineffective efforts and auto-triggering.

Human ex-vivo model of Stanford type B aortic dissection.

OBJECTIVE: To report a new human ex vivo model of type B aortic dissection (TBAD) and to assess if the locations of the primary entry tear determine the patterns of dissection propagation. METHODS: Twenty fresh human aortas were harvested. TBADs were surgically initiated 2 cm below the left subclavian artery at four different locations (lateral, n = 5; medial, n = 5; anterior, n = 5; posterior, n = 5). Aortas were thereafter connected to a bench-top pulsatile flow model to induce antegrade propagation of the dissection. RESULTS: Antegrade propagation of the dissection was achieved and reached at least the celiac trunk (CT) in all the cases. Dissection was propagated to the renal aorta in 16 (80%) and infrarenal aorta in seven cases (35%). Left renal artery with or without the CT originated more often from the false channel when primary entry tear was lateral. Right renal artery and the CT most often originated from the false channel when primary entry tear was medial. When the CT was the only one originating from the false channel, primary entry tear was more often anterior, whereas when it originated from the true channel, it was more often posterior. CONCLUSIONS: This human ex vivo model of TBAD is reproducible, since, in all the aortas, extended dissection was achieved and provides the first model of human aortic dissection with infrarenal aorta extension allowing future assessment of endovascular devices developed for human use. Furthermore, it allows clarification of the patterns of aortic dissection propagation and visceral and renal artery involvement according to the site of the primary entry tear.

Assessment of lung ultrasound for early detection of respiratory complications in thoracic surgery.

BACKGROUND AND OBJECTIVES: To assess lung ultrasound for the diagnosis and monitoring of respiratory complications in thoracic surgery. METHODS: Prospective observational study in a University hospital, single institution. Adult patients scheduled for pulmonary resection surgery excluding pneumonectomy. An ultrasound follow-up was performed from the day before the surgery to the third day after surgery with calculation of B-line and lung score (reaeration and loss of aeration scores). Respiratory complications were collected throughout the hospitalization period. RESULTS: Fifty-six patients were included. Eighteen patients presented a respiratory complication (32%), and they presented significantly higher BMI and ASA scores. Patients operated by videothoracoscopy were less at risk of complications. At day 3, a reaeration score ≤ 2 on the ventilated side or ≤ -2 on the operated side, and a B-line score>6 on the operated side were in favor of a complication. CONCLUSION: Lung ultrasound can help in the diagnosis of respiratory complications following pulmonary resection surgery.

Analgesic Drug Prescription After Carpal Tunnel Surgery: A Pharmacoepidemiological Study Investigating Postoperative Pain.

BACKGROUND AND OBJECTIVES: Carpal tunnel syndrome is a frequent cause of neuropathic pain of the upper limb. Surgery is often proposed in second-line treatment, leading to an expected decrease in analgesic drug consumption. The main objective of this study was to investigate the variations in analgesic drug prescriptions, with a special focus on constant or increasing prescription patterns, before and after surgery for carpal tunnel syndrome. METHODS: We designed a retrospective cohort study of French beneficiaries from the health insurance system in Midi-Pyrénées area. All patients undergoing carpel tunnel surgery during a specified period were identified and included. Definition of increased or constant prescription of analgesics was based on the comparison of the accumulated defined daily doses received by months and a difference between early preoperative (2 months before) and late postoperative period (2-12 months after surgery) superior to a -3.5 margin. We performed 4 multivariate logistic regression models to identify factors associated with increased or constant analgesic drug prescription patterns (for all analgesics, opioid, antineuropathic, nonopioid drugs). RESULTS: Among the 3665 patients included, 3255 (89%) received at least 1 analgesic drug during the late postoperative period (39% [n = 1426] for opioids and 15% [n = 563] for antineuropathic drugs). Prescription of analgesic, opioid, or antineuropathic drugs was maintained or increased in the late postoperative period in 11%, 5%, and 3% of the population, respectively. High levels of preoperative pain and female sex were associated with an increase in opioid use, whereas inpatient surgery (vs ambulatory surgery), high levels of preoperative pain, and psychiatric disorders were found to be associated with an increase in antineuropathic drug use. CONCLUSIONS: This study revealed that approximately 3% to 5% of patients undergoing carpal tunnel surgery had persistent and even increased use of opioid or antineuropathic drugs more than 2 months after surgery, in relation with possible chronic postoperative pain. Considering the incidence of carpal tunnel syndrome, the risks associated with persistent opioid use in this population should be further monitored.

Analgesic drug consumption increases after knee arthroplasty: a pharmacoepidemiological study investigating postoperative pain.

Knee arthroplasty remains the gold standard in the treatment of severe osteoarthritis. Chronic postoperative pain has been reported with a prevalence ranging from 15% to 47%. The aim of this study was to compare analgesic drug consumption before and after surgery as an indicator of pain after knee surgery. A pharmacoepidemiological method comparing analgesics and antineuropathic issues 1 year before and 1 year after surgery was used. All patients who underwent knee arthroplasty in the Midi-Pyrenees region (2.5 million inhabitants) were identified through the Health Insurance System Database. Increase of drug issues (all analgesics, antineuropathic drugs, strong opioids) was calculated and compared between several periods surrounding the surgery (12 months, 2 months, and 10 months before and after the knee arthroplasty). A multivariate logistic regression model was used to identify factors associated with chronic postoperative pain. The study included 1939 patients. An increase in analgesic, antineuropathic, and opioid drug consumption was observed the year after the surgery in 47.3%, 8.6%, and 5.6% of patients, respectively. Multivariate analysis found a significant association between type of surgery (total knee vs unicompartmental arthroplasty) and analgesic consumption 1 year after surgery, and between preoperative pain and psychiatric vulnerability and increase in neuropathic drug dispensing. Conversely, older age was considered as a protective factor. This study revealed that an increase in the issue of different analgesic drugs is present in half of patients 1 year after knee arthroplasty. Several associated factors of drug consumption (preoperative pain, type of surgery, and psychiatric disorder) were identified.

Adverse drug reactions to gabapentin and pregabalin: a review of the French pharmacovigilance database.

BACKGROUND: Gabapentin and pregabalin are widely used as antineuropathic pain drugs. Their use is also associated with the development of adverse drug reactions (ADRs), mainly neuropsychiatric. OBJECTIVE: The aim of this work was to study 'serious' and/or 'unexpected' adverse reactions associated with pregabalin and gabapentin. STUDY DESIGN: We studied ADRs reported to the French Pharmacovigilance System occurring between 1995 and 2009. MAIN OUTCOME MEASURE: For each ADR associated with gabapentin or pregabalin, we noted year, patient age and sex, type of adverse reaction, as well as the imputability score. Reporting rate of serious ADRs for gabapentin and pregabalin was estimated with regard to data of use (obtained from the French National Health Insurance Fund) using the defined daily dose. A global and descriptive analysis of the adverse reactions for each drug is presented. Secondly, details of deaths and ADRs with an imputability score of at least 'probable' or 'likely' were presented. RESULTS: Overall, 1333 cases were recorded (725 related to gabapentin, 608 related to pregabalin), mainly neuropsychiatric ADRs. Among the 22 deaths recorded, 8 were related to gabapentin in obstetrical situations. Other less well-documented ADRs were identified, such as hepatitis associated with gabapentin and haematological ADRs associated with pregabalin. CONCLUSION: This study confirmed the prevalence of neuropsychiatric ADRs associated with gabapentin or pregabalin. A high rate of death occurred with gabapentin in an obstetrical context. New adverse reactions have been noted, such as haematological or hepatic adverse reactions associated with pregabalin and gabapentin, respectively.