several series have shown similar disease - specific survival and recurrence rates for pn compared with radical nephrectomy for renal masses smaller than 4 to 7 cm with the preservation of renal function [ 2 - 4 ] . patients undergoing radical nephrectomy for renal masses tend to have a higher incidence of chronic renal insufficiency , cardiovascular events , and proteinuria than do patients undergoing pn [ 3,5 - 8 ] . despite the advantage of preserving renal mass pn has the potential to elicit a renin - angiotensin response in the treated kidney and thus hypertension . hypothetically , renal artery injury from hilar clamping or the compressive effects of bolsters on the parenchymal defect after mass removal could mimic the goldblatt one - clip two - kidney model of hypertension . in short , reduced blood flow and glomerular capillary pressure in the affected kidney could cause renin release and ensuing hypertension . a handful of case reports have indicated that pn may precipitate postoperative hypertension in the short term [ 11 - 13 ] . one older small series of 14 patients showed no long - term deterioration of blood pressure ( bp ) after pn in patients with a solitary kidney , although that study did not include comparison of postoperative bp with preoperative bp . the renal trauma literature suggests that renal injury can lead to postoperative hypertension in the form of renal vascular injuries or the often mentioned " page kidney " after renal repair [ 15 - 17 ] . the donor transplant nephrectomy literature has conflicting studies with respect to the loss of renal mass on bp , with some showing a high incidence of hypertension after surgery   and one older study showing a minimal effect on long - term bp . the importance of hypertension with respect to renal preservation is highlighted by a recent study identifying it as an independent risk factor for renal loss in radical and partial nephrectomies . therefore , the effect of pn for renal masses on postoperative bp is important for clinical follow - up and is not well defined . the hypothesis suggesting that pn can induce a postoperative hypertensive response as a consequence of renin - angiotensin activation appears plausible . therefore , our aim was to initiate an exploratory study to describe the effect of pn on short- and long - term postoperative bp . a single - center , ethics - approved retrospective review of all pns performed over 6 years ( 2002 to 2008 ) was conducted at the queen elizabeth ii health sciences center , department of urology in halifax , nova scotia , canada . the 6-year cut - off was selected because before this time period , pn was not a common procedure . consent forms and explanatory cover letters were mailed to all 112 consecutive patients originally identified , and 74 provided informed consent . of the 74 family physician offices contacted , 62 released information on bp and medications . the inclusion criteria were patients 18 years of age , who underwent pn for presumed renal cell carcinoma , and who were followed by a family physician and had at least two bp readings taken during the 2 years before surgery and at least two bp measurements taken > 1 month after surgery . the initial postoperative period was excluded to avoid effects of postoperative pain and anxiety on bp . preoperative bp data were generated before patients were diagnosed with a renal cancer , thereby excluding anxiety - induced bp alterations . we excluded patients if consent was not given for information release or if insufficient bp information was available ( less than two readings before or after surgery ) . patients on dialysis within 2 years of surgery were excluded , thus eliminating the complexity of dialysis - related bp variability . patients pregnant within 2 years before or after surgery were excluded . patients with metastatic renal cancer within 2 years before or after surgery were excluded , because associated pain , anxiety , and paraneoplastic syndromes could complicate results . patients with chronic renal failure ( creatinine clearance < 20 ml / h ) and patients with greater than one renal surgery were also excluded . of 62 patients available before exclusions , 10 had insufficient bp information , 2 developed early metastatic disease , 1 developed kidney failure , and 1 had bilateral kidney surgeries . the main study variables assessed were mean systolic bp ( sbp ) and diastolic bp ( dbp ) . unfortunately , owing to the retrospective nature of this study , we could not control for the temporal variability of bp readings before and after surgery . therefore , bps taken during the 2-year period before surgery were averaged , whereas the mean of bps taken after surgery was stratified by the early postoperative period ( 1 - 12 months ) and the late postoperative period ( 12 months to the end of follow - up ) . the secondary endpoint assessed was the mean number of bp medications used before ( at the last family physician office visit before surgery ) and after surgery . postoperative bp medication tallies were also subdivided into the early and delayed postoperative period as above , with the number of medications at the last family physician visit closest to 1 year postoperatively and those at the last follow - up incorporated into our analysis . the number of patients taking angiotensin - converting enzyme inhibitors ( acei ) or angiotensin receptor blockers ( arb ) was compared independent of other medications . differences between mean sbps and dbps before and after surgery were analyzed with a paired t test . medication comparisons from before and after surgery were analyzed by using a chi - squared test . a single - center , ethics - approved retrospective review of all pns performed over 6 years ( 2002 to 2008 ) was conducted at the queen elizabeth ii health sciences center , department of urology in halifax , nova scotia , canada . the 6-year cut - off was selected because before this time period , pn was not a common procedure . consent forms and explanatory cover letters were mailed to all 112 consecutive patients originally identified , and 74 provided informed consent . of the 74 family physician offices contacted , 62 released information on bp and medications . the inclusion criteria were patients 18 years of age , who underwent pn for presumed renal cell carcinoma , and who were followed by a family physician and had at least two bp readings taken during the 2 years before surgery and at least two bp measurements taken > 1 month after surgery . the initial postoperative period was excluded to avoid effects of postoperative pain and anxiety on bp . preoperative bp data were generated before patients were diagnosed with a renal cancer , thereby excluding anxiety - induced bp alterations . we excluded patients if consent was not given for information release or if insufficient bp information was available ( less than two readings before or after surgery ) . patients on dialysis within 2 years of surgery were excluded , thus eliminating the complexity of dialysis - related bp variability . patients pregnant within 2 years before or after surgery were excluded . patients with metastatic renal cancer within 2 years before or after surgery were excluded , because associated pain , anxiety , and paraneoplastic syndromes could complicate results . patients with chronic renal failure ( creatinine clearance < 20 ml / h ) and patients with greater than one renal surgery were also excluded . of 62 patients available before exclusions , 10 had insufficient bp information , 2 developed early metastatic disease , 1 developed kidney failure , and 1 had bilateral kidney surgeries . the main study variables assessed were mean systolic bp ( sbp ) and diastolic bp ( dbp ) . unfortunately , owing to the retrospective nature of this study , we could not control for the temporal variability of bp readings before and after surgery . therefore , bps taken during the 2-year period before surgery were averaged , whereas the mean of bps taken after surgery was stratified by the early postoperative period ( 1 - 12 months ) and the late postoperative period ( 12 months to the end of follow - up ) . the secondary endpoint assessed was the mean number of bp medications used before ( at the last family physician office visit before surgery ) and after surgery . postoperative bp medication tallies were also subdivided into the early and delayed postoperative period as above , with the number of medications at the last family physician visit closest to 1 year postoperatively and those at the last follow - up incorporated into our analysis . the number of patients taking angiotensin - converting enzyme inhibitors ( acei ) or angiotensin receptor blockers ( arb ) was compared independent of other medications . differences between mean sbps and dbps before and after surgery were analyzed with a paired t test . medication comparisons from before and after surgery were analyzed by using a chi - squared test . statistical analysis was performed with graphpad prism ver . 4.01 ( graphpad software inc . , la jolla , ca , usa ) . the overall mean preoperative sbp / dbp was 132.4/78.0 mmhg and when compared with the overall postoperative bp ( 132.2/76.7 mmhg ) was not significantly different ( p=0.87 for systolic and p=0.16 for diastolic ) . table 2 shows the comparison of preoperative bp with bp in the early postoperative period ( 1 month-1 year ) and the late postoperative period ( > 1 year ) . no significant difference was found in diastolic or systolic bp when preoperative measurements were compared with measurements in the early postoperative period ( p0.3 ) . assessment of late postsurgery bp ( > 12 months after surgery ) identified no significant difference in mean sbp compared with before surgery , with a median follow - up time of 24 months ( p=0.34 ) . however , the corresponding mean dbp was significantly lower in the delayed group ( 76.4 mmhg vs. 78.0 mmhg ) , with an absolute difference of 1.6 mmhg ( p=0.01 ) . the cohort was also stratified by the laparoscopic and open approach with no significant difference in postoperative bp noted in either group relative to preoperative bp ( data not shown ) . as depicted in fig . 1 , there was no significant difference between the mean number of bp medications prescribed preoperatively ( 1.2 ) , at 12 months ( 1.4 , p=0.38 ) , and beyond 12 months ( 1.3 , p=0.44 ) . furthermore , the number of patients prescribed acei and arb anti - hypertensives did not differ significantly from preoperative to any postoperative time points ( p=0.58 ) , with a total of 3/32 patients undergoing a dosage increase in either of these medications . this is the first series to determine the effects of pn on preoperative versus postoperative bp . with the use of bp measurements routinely performed by family physicians , we retrospectively compared preoperative and postoperative bps in 48 patients with a follow - up of 2 years . in the total cohort , there was no significant change in mean sbp or dbp within 1 year after surgery . beyond 1 year after surgery , a minor improvement in dbp ( 1.6 mmhg ) occurred with no change in sbp . therefore , bp in the short - term and long - term appears to be preserved after pn , although the possibility remains for an increase or decrease in bp in a cohort with a longer follow - up or more patients recruited . these findings reject the hypotheses suggesting that the technique of pn can induce a postoperative hypertensive response as a consequence of renin - angiotensin activation . an alternative explanation is that renal masses themselves could cause compressive effects on surrounding renal parenchyma or generate paraneoplastic syndromes that result in hypertension . a recent study from montenegro showed an improvement in hypertension in 24 patients undergoing radical nephrectomy for renal cell carcinoma . the average preoperative bp in that study was particularly high ( 161/99 mmhg ) compared with our study ( 132/78 mmhg ) , and no details on tumor size or methods of recording bp were provided . given that all patients in the montenegro study underwent a radical nephrectomy , it is likely that the patient population in that study had much larger tumors than did our cohort , which could have a stronger negative influence on bp through paraneoplastic or compressive effects on the renal parenchyma . a major strength of our study is that preoperative bp data were generated before the patients were diagnosed with a renal cancer to reduce any anxiety or stress - related impact on bp , which was not likely the case in the study from montenegro . several transplant nephrectomy studies are contradictory to the montenegro study and actually show an increase in bp after nephrectomy . the donor nephrectomy patient population is different in that these patients are highly selected , are younger in age , have minimal baseline comorbidities , and lack the potential paraneoplastic or compressive effects of renal tumors . with respect to our study , the possibility remains that postsurgery bp elevation could be masked by preoperative hypertension caused by the renal mass ( compressive effects or paraneoplastic syndrome ) . indeed , one cause of hypertension ( the renal mass ) could have been replaced by another cause of hypertension ( surgical factors stimulating angiotensin ) , thus balancing out the effect of pn on bp . alternatively , hypertension may have been caused by the tumor , whereby removing the tumor improved the bp as noted by the improvement in dbp in the total cohort beyond 1 year and the trend toward improvement in sbp and dbp in those undergoing an open approach . however , the prevalence of preoperative hypertension in our study population ( 69% ) was similar to the published canadian prevalence of hypertension in this age group ( 66% ) , which suggests that there was minimal if any effect of renal masses on the incidence of preoperative hypertension . one drawback in our study design is a potential bias for selecting patients who are closely followed with bp measurements by family physicians . these patients may have tighter bp control with medications , which could lead to a false - negative effect on bp . we addressed this concern by tabulating the number of bp medications the patients were taking before and after surgery . there were no significant differences in the number of bp medications taken before and after surgery . we were only able to reliably track acei and arb medication dosage changes and found no significant dosage changes , which suggests a low likelihood of significant dosage changes to other antihypertensives . unfortunately , owing to the retrospective nature of our study , we were unable to account for changes in medications other than antihypertensives that could also affect blood pressure . another limitation in our study was the lack of a control comparison group such as patients who underwent radical nephrectomy . however , because we compared patients in a pairwise fashion ( preoperative to postoperative ) and demonstrated no effect on bp , a control group would not have changed our conclusion with respect to our original hypothesis . in addition , the majority of patients who undergo pn in our institution have masses < 4 cm , such that a radical nephrectomy cohort would not be an equivalent control group because these patients typically have much larger renal masses with more potential to impact bp . another limitation of our study was the lack of control of bp measurements with respect to setting , time of day , and technique . however , by using a paired design such that the same family physician performed the measurement before and after surgery , we tried to minimize inter - observer variability . this study , although exploratory , provides the first evidence that pn for small renal masses in a contemporary cohort is not likely a risk factor for worse bp outcome compared with before surgery . the lack of bp deterioration is particularly important in view of the recent evidence identifying hypertension as an independent risk factor for renal impairment after partial or radical nephrectomy . overall , these results should be generalizable with respect to the effect of pn on bp in the cohort of patients with renal masses less than 4 cm .
purposethe effects of partial nephrectomy ( pn ) on postoperative blood pressure ( bp ) are not known , and pn has the potential to worsen bp . 
 we therefore sought to determine whether pn alters postoperative bp.materials and methodspatients who underwent pn for suspected malignancy at our institution from 2002 to 2008 were included . 
 data on bp and medication from before and after pn were retrieved from family physicians . 
 bp and number of antihypertensive medications were compared after surgery with preoperative values by use of paired t tests and chi - squared analyses , respectively.resultsof 74 patients undergoing pn and providing consent , 48 met the inclusion and exclusion criteria , with a median follow - up of 24 months . for the early postoperative period ( 1 month to 1 year after surgery ) , the mean bps ( 132.3/77.0 mmhg ) were unchanged compared with preoperative values ( 132.4/78.0 mmhg ; p=0.59 systolic bp and p=0.30 diastolic bp ) . for the later postoperative period ( beyond 1 year after surgery ) , the mean postoperative systolic bp was unchanged from the mean preoperative systolic bp ( 131.2 mmhg vs. 132.4 mmhg , respectively ; p>0.30 ) . 
 however , 
 the corresponding average diastolic bp was lower in the long term ( 78.0 mmhg versus 76.4 mmhg respectively ; p=0.01 ) . 
 no significant difference in the mean number of bp medications prescribed preoperatively , at one year , and beyond one year was identified ( p>0.37).conclusionspn does not result in initial or long - term postoperative deterioration in bp .