Title: Severe postoperative hypotension after carotid endarterectomy: risk factors and perioperative outcome.  
Authors: M. Latorre, A. Mases, S. Sabaté, C. Díaz, E. Soler, J. Vallès
BACKGROUND AND GOAL OF STUDY
Carotid endarterectomy (CEA) for stroke prevention is associated with perioperative haemodynamic instability and this has been correlated to worst outcome. Our aim was to analyse the incidence of severe hypotension after CEA, to identify possible risk factors for such complication and evaluate a possible association of severe hypotension with perioperative morbidity.    
MATERIAL AND METHODS
We retrospectively review data of 201 patients who underwent CEA for carotid stenosis under general anaesthesia in our institution from 2005 to 2011. We collected demographic data, patient comorbidities, chronic pharmacological treatments, degree of carotid stenosis and whether it was symptomatic, details of surgery and anaesthesia and data of post-procedural evolution and complications at 30 days after surgery. We defined severe hypotension as the need for the administration of a continuous perfusion of intravenous noradrenaline in the postoperative period. All data was obtained from medical records. Mann-Whitney U and Chi square tests were used to compare means or percentages respectively.
RESULTS AND DISCUSION
The incidence of severe hypotension after CEA was 13,4%. When comparing data between both groups of patients (hypotension vs no hypotension) we did not find significant differences in demographics, surgical site, degree of stenosis, symptomatic stenosis, degree of contralateral carotid disease, previous contralateral surgery and duration of surgery. With respect to preoperative comorbidities and chronic antihypertensive treatments, we only found estimated glomerular filtration rate <45 mL/min/1,73m2 to be associated with a major incidence of postoperative hypotension (Table 1).  
Table 1 Pre-surgical variables
Preoperative variables	 	 	 
Hypertension, n(%)	141 (81)	24 (88.9)	0,425
Preoperative Haemoglobin (g/dL), n(%)	13.8 (12.5 - 15)	13.3 (12.4 - 14.6)	0,392
Peripheral vascular disease, n(%)	78 (44.8)	8 (29.6)	0,409
Coronary artery disease, n(%)	48 (27.6)	9 (33.3)	0,923
Diabetes mellitus, n(%)	54 (31)	13 (48.1)	0,085
Dislipidemia, n(%)	131 (75.3)	22 (81.5) 	0,63
Chronic heart failure, n(%)	6 (3.4)	2 (7.4)	0,293
Chronic Kidney disease, n(%)	20 (11.5)	6 (22.2)	0,129
GFR (CKD-EPI) < 45	16 (9.2)	7 (25.9)	0,015
Glomerular Filtration Rate, CKD-EPI	72.2 (60.2 - 90.5)	79.2 (40.8 - 84.8)	0,812
COPD, n(%)	52 (29.9)	5 (18.5) 	0,288
Medical treatments, n(%)	 	 	 
Diuretics	72 (43.1)	13 (49)	0,531
ß-Blockers	53 (31.9)	9 (34.6)	0,823
Statins	136 (78.2)	23 (85.2)	0,611
ACE inhibitors	64 (36.8)	13 (48.1)	0,291
ARBs	35 (21.1)	5 (19.2)	0,829
Nitrats	13 (7.8)	1 (3.8)	0,697
CCB 	51 (30.7)	6 (23.1)	0,496
No. of Antihypertensive Drugs, n(%)	 	 	0,928
0	40 (23)	4 (14.8)	 
1	44 (25.3)	8 (29.6)	 
2	48 (27.6)	7 (25.9)	 
3+	42 (24.1)	8 (29.7)	 
Severe postoperative hypotension was associated to a longer ICU stay [median hours (IQR): 22 (21-24) vs 24(23-45); p<0.001)] but did not have any impact in length of hospital stay days[5 (4-6) vs 5 (4-7); p=0.978]. Table 2 shows 30 day perioperative complications. 
Complications		
Any complications	31 (18.9)	8 (29.6)	0,205
Exitus, n(%)	1 (0.6)	2 (7.4)	0,052
Transfusion, n(%)	17 (10.4)	4 (14.8)	0,507
SDRA, n(%)	0 (0)	2 (7.4)	0,019
Atelectasia, n(%)	1 (0.6)	2 (7.4)	0,052
Surgical wound infection, n(%)	2 (1.2)	0 (0)	0,565
Infeccio greu, n(%)	1 (0.6)	 1 (3.7)	0,265
MACCE, n(%)	18 (10.3)	4 (14.8)	0,507

CONCLUSIONS 
Severe postoperative hypotension after CEA is difficult to predict. Although not uncommon, it does not increase the incidence of perioperative complications. 



REFERENCES
1.	Park BD, Divinagracia T, et al. Predictors of clinically significant postprocedural hypotension after carotid endarterectomy and carotid angioplasty with stenting. J Vasc Surg. 2009 Sep;50(3):526-33.
2.	Tan TW, Eslami MH, et al. The need for treatment of hemodynamic instability following carotid endarterectomy is associated with increased perioperative and 1-year morbidity and mortality. J Vasc Surg. 2014 Jan;59(1):16-24.

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