Kamran G. Ghori

Aprotinin decreases the incidence of cognitive deficit following CABG and cardiopulmonary bypass: A pilot randomized controlled study

PurposeCognitive deficit after coronary artery bypass surgery (CABG) has a high prevalence and is persistent. Meta-analysis of clinical trials demonstrates a decreased incidence of stroke after CABG when aprotinin is administrated perioperatively. We hypothesized that aprotinin administration would decrease the incidence of cognitive deficit after CABG.MethodsThirty-six ASA III–IV patients undergoing elective CABG were included in a prospective, randomized, single-blinded pilot study. Eighteen patients received aprotinin 2 × 106 KIU (loading dose), 2 × 106 KIU (added to circuit prime) and a continuous infusion of 5 × 105 KIU·hr−1. A battery of cognitive tests was administered to patients and spouses (n = 18) the day before surgery, four days and six weeks postoperatively.ResultsFour days postoperatively new cognitive deficit (defined by a change in one or more cognitive domains using the Reliable Change Index method) was present in ten (58%) patients in the aprotinin group compared to 17 (94%) in the placebo group [95% confidence interval (CI) 0.10–0.62,P = 0.005); (P = 0.01)]. Six weeks postoperatively, four (23%) patients in the aprotinin group had cognitive deficit compared to ten (55%) in the placebo group (95% CI 0.80−0.16,P = 0.005); (P = 0.05).ConclusionIn this prospective pilot study, the incidence of cognitive deficit after CABG and cardiopulmonary bypass is decreased by the administration of high-dose aprotinin.RésuméObjectifLe déficit cognitif qui survient après un pontage aortocoronarien (PAC) persiste seion une forte prévalence. Une méta-analyse d’essais cliniques démontre une incidence réduite d’accident vasculaire cérébral après un PAC quand l’aprotinine périopératoire est administrée. Nous avons émis l’hypothèse que l’aprotinine réduirait l’incidence de déficit cognitif après un PAC.MéthodeTrente-six patients, d’état physique III–IV selon l’ASA, devant subir un PAC réglé, ont été inclus à l’étude pilote, prospective, randomisée et à simple insu. Dix-huit patients ont reçu 2 × 106 UIK d’aprotinine (dose de charge), 2 × 106 UIK (ajouté au circuit d’amorce) et une perfusion continue de 5 × 105 UIK·h−1. Une batterie de tests cognitifs a été administrée aux patients et à leurs conjoints (n = 18) le jour précédant l’opération, quatre jours et six semaines après l’opération.RésultatsQuatre jours après l’opération, un nouveau déficit cognitif (défini par une modification dans au moins un domaine de connaissances selon la méthode de l’index fiable de changement) était présent chez dix (58 %) patients ayant eu de l’aprotinine, comparativement à 17 (94 %) du groupe placebo [intervalle de confiance de 95 % (IC) 0, 10–0,62, P = 0,005) ; (P = 0,01)]. Six semaines après l’opération, quatre (23 %) patients du groupe aprotinine présentaient un déficit cognitif comparativement à dix (55 %) du groupe placebo (IC de 95 % 0,80−0, 16,P = 0,005) ; (P= 0,05).ConclusionL’étude pilote prospective montre que l’incidence de déficit cognitif après un PAC et une circulation extracorporelle est réduite par l’administration d’aprotinine à doses élevées.

The effect of lidocaine on in vitro neutrophil and endothelial adhesion molecule expression induced by plasma obtained during tourniquet-induced ischaemia and reperfusion.

Background: Changes in neutrophil and endothelial adhesion molecule expression occur during perioperative ischaemia and reperfusion (I/R) injury. We investigated the effects of lidocaine on neutrophil-independent changes in neutrophil and endothelial adhesion molecule expression associated with tourniquet-induced I/R. Methods: Plasma was obtained from venous blood samples (tourniquet arm) taken before (baseline), during, 15 min, 2 and 24h following tourniquet release in seven patients undergoing elective upper limb surgery with tourniquet application. Isolated neutrophils from healthy volunteers (n = 7) were pretreated in the presence or absence of lidocaine (0.005, 0.05 and 0.5 mg mL−1) for 1 h, and then incubated with I/R plasma for 2 h. Human umbilical vein endothelial cells (HUVECs) were pretreated in the presence or absence of lidocaine (0.005, 0.05 and 0.5 mg mL−1) for 1 h, and then incubated with the plasma for 4 h. Adhesion molecule expression was estimated using flow cytometry. Data were analysed using ANOVA and post hoc Student-Newman-Keuls tests. Results: I/R plasma (withdrawn 15 min following tourniquet release) increased isolated neutrophil CD11b (P = 0.03), CD18 (P = 0.01) and endothelial intercellular adhesion molecule-1 (ICAM-1) (P = 0.008) expression compared to baseline. CD11b, CD18 and ICAM-1 expression on lidocaine (0.005 mg mL−1) treated neutrophils was similar to control. CD11b (P < 0.001), CD18 (P = 0.03) and ICAM-1 (P = 0.002) expression on lidocaine (0.05 mg mL−1) treated neutrophils and HUVECs was less than that on controls. Conclusion: Increased in vitro neutrophil and endothelial cell adhesion molecule expression on exposure to plasma obtained during the early reperfusion phase is diminished by lidocaine at greater than clinically relevant plasma concentrations.

Plasma concentrations of nitric oxide products and cognitive dysfunction following coronary artery bypass surgery

Background and objective: Prospective longitudinal studies now indicate that cognitive dysfunction following coronary artery bypass surgery (CABG) is both common and persistent. This dysfunction is due in part to the inflammatory response and cerebral ischaemia‐reperfusion, with nitric oxide (NO) as an important mediator of both. We hypothesized that a clinically significant association exists between plasma concentrations of nitrate/nitrite (Symbol/Symbol) and cognitive dysfunction after CABG. Symbol. No caption available. Symbol. No caption available. Methods: Cognitive assessment was performed on 36 adult patients the day before CABG, on the fourth postoperative day and 3 months postoperatively. Patient spouses (n = 10) were also studied. Results: A new cognitive deficit was present in 22/36 (62%) 4 days postoperatively and in 16/35 (49%) of patients, 3 months postoperatively. Patients who had cognitive dysfunction 3 months postoperatively were more likely to have cognitive dysfunction and increased plasma Symbol/Symbol concentrations compared to the non‐deficit group preoperatively (22.6 (9.2) vs. 27.6 (8.4)) (P = 0.002). Plasma NOx (Symbol plus Symbol) concentrations were greater in patients with cognitive dysfunction 3 months postoperatively, 2 h (24.2 (6.3) vs. 19.1 (5.2)) (P = 0.002), and 12 h postoperatively (24.8 (7.6) vs. 18.8 (5.6)) (P = 0.001). There was, however, a time course similarity in NOx elevations for both deficit and non‐deficit groups. Conclusions: Perioperative plasma NOx concentrations do not serve as an effective biomarker of cognitive deficit after CABG.

Effect of midazolam on in vitro cerebral endothelial ICAM-1 expression induced by astrocyte-conditioned medium

Background and objective: Astrocytes exposed to hypoxia produce pro‐inflammatory cytokines and upregulate intercellular adhesion molecule‐1 on cerebral endothelium. This study investigated the effects of midazolam on this response. Methods: Mouse astrocytes were exposed to 4 h of hypoxia and 24 h of reoxygenation. Astrocyte‐conditioned medium were applied to mouse cerebral endothelial cell cultures for 4 h and 24 h in normoxia. Endothelial cells were pre‐incubated for 1 h with midazolam (0, 5, 50 μg L−1). Flow cytometry was used to estimate endothelial ICAM‐1 expression. IL‐1β concentrations were measured with ELISA. Repeated comparisons were made using ANOVA and post hoc Tukey Test as appropriate. Data are mean (SD). Results: Mouse cerebral endothelial cell ICAM‐1 expression was greater after 24 h exposure to hypoxia–reoxygenation astrocyte‐conditioned medium compared to normoxic astrocyte‐conditioned medium (mean channel flouresence 112.5 (9.5) vs. 81.5 (7.5), P = 0.01). ICAM‐1 expression was decreased by midazolam (5 μg L−1) compared to control (mean channel flouresence 81.35 (7.5) vs. 112.5 (9.5), P = 0.01). Supernatant IL‐1β concentrations (pg mL−1) in astrocytes exposed to hypoxia–reoxygenation were greater than those exposed to normoxia (16.41 (2.35) vs. 10.5 (2.13), P = 0.01). Conclusion: We conclude that decreased cerebral endothelial ICAM‐1 expression in response to activated glial cell compartment by midazolam may decrease post ischaemic brain inflammation and secondary brain injury.

The effect of midazolam on neutrophil mitogen-activated protein kinase.

Background Neutrophil p38 mitogen-activated protein kinase (MAPK) is a key enzyme in the intracellular signalling pathway that is responsible for many neutrophil functions, which are important in neutrophil–endothelial interaction. The imidazole compounds are inhibitors of this enzyme system. The objectives of this in-vitro investigation were to examine the effect of midazolam on neutrophil p38 MAPK activation (phosphorylation) following in-vitro ischaemia–reperfusion injury, and the expression of adhesion molecule CD11b/CD18. Methods In-vitro injury was produced by incubating the neutrophils with N-formyl-methionyl-leucyl-phenylalanine. Neutrophils were treated with either 10 or 50 times the therapeutic plasma concentrations of midazolam and SB203580 (known inhibitor of p38 MAPK). The concentrations of phosphorylated p38 MAPK and expression of neutrophil adhesion molecules CD11b/CD18 were measured. Flow cytometry was used to estimate adhesion molecule expression. Results The concentration of phosphorylated p38 MAPK was less in neutrophils subjected to ischaemia–reperfusion and treated with midazolam either 10 μg ml−1 [13.6 (3.2) ng ml−1] or 50 μg ml−1 [12.4 (3.6) ng ml−1], or SB203580 [13 (2.6) ng ml−1] than those subjected to ischaemia–reperfusion alone [18 (3.18) ng ml−1] at a P value of less than 0.05. Following ischaemia–reperfusion injury, CD11b/CD18 expression (expression mean channel fluorescence) on neutrophils was greater when compared with controls. The magnitudes of CD11b and CD18 expression on ischaemia–reperfusion-injured neutrophils were decreased by midazolam (10 μg ml−1) as compared with control of 10.3 (2.6) vs. 14 (3.1) μg ml−1 and 28.3 (12.9) vs. 44 (12.1) μg ml−1, respectively, at a P value of less than 0.05. Similarly, the expression of CD11b and CD18 was less in ischaemia–reperfusion-injured neutrophils treated with inhibitor of 10.3 (2.8) vs. 14 (3.18) μg ml−1 and 29.5 (12.5) vs. 44.3 (12.3) μg ml−1 when compared with controls at a P value of less than 0.05. Conclusion Midazolam diminishes in-vitro ischaemia–reperfusion-induced phosphorylation of p38 MAPK in neutrophils. This decrease in p38 MAPK activation results in decreased neutrophil CD11b/CD18 molecule expression.

The effect of midazolam on cerebral endothelial (P-selectin and ICAM-1) adhesion molecule expression during hypoxia-reperfusion injury in vitro.

Background and objective: Hypoxia‐reperfusion injury is an important determinant of secondary brain injury. In the acute phase of cerebral reperfusion, pro‐inflammatory events enhance expression of cerebral endothelial (intercellular adhesion molecule‐1 and P‐selectin) adhesion molecules, which play an important role in brain hypoxia‐reperfusion injury. Midazolam is the most commonly used sedative in patients with brain injury. The objective of this investigation was to examine the effect of midazolam on the expression of cerebral endothelial intercellular adhesion molecule‐1 and P‐selectin during hypoxia‐reperfusion injury in vitro. Methods: The up‐regulation of mouse cerebral endothelial cells intercellular adhesion molecule‐1 and P‐selectin was assessed following hypoxia‐reoxygenation (hypoxia‐reperfusion). Cells were pre‐treated with three different concentrations of midazolam (0, 5 and 50 &mgr;g mL−1) prior to hypoxia. Flow cytometry was used to estimate adhesion molecule expression mean channel fluorescence. Data are presented as mean ± SD. Results: Mouse cerebral endothelial cell intercellular adhesion molecule‐1 and P‐selectin expression was greater after exposure to hypoxia‐reoxygenation compared to normoxia (mean channel fluorescence) 241 ± 12 vs. 140 ± 7 and 120 ± 14 vs. 46 ± 7, respectively, P < 0.05. Intercellular adhesion molecule‐1 and P‐selectin expression was decreased by midazolam (5 &mgr;g mL−1) pre‐incubation compared to control, mean channel fluorescence 184 ± 10 vs. 241 ± 12 and 51 ± 7 vs. 120 ± 14, respectively, P < 0.05. Midazolam at 50 &mgr;g mL−1 had the same effect as 5 &mgr;g mL−1. Conclusion: Pre‐treatment with midazolam diminishes increased expression of cerebral endothelial intercellular adhesion molecule‐1 and P‐selectin expression following hypoxia‐reoxygenation.