Benign prostatic hyperplasia (BPH)

Benign prostatic hyperplasia (BPH)

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a common in men more than 40 years of age. It is characterized by urinary urgency, incontinence, frequency, nocturnal, a weak urine flow and intermittency [1].  The etiology by which BPH occurs is still unknown. It is believed that the long-term effects of the synthesis of testosterone has role, while some authors believe that there is a hereditary hypothesis [2].  BPH is considered when the size of the prostate is bigger than normal and is associated with obstructive symptoms while micturition. The normal size of the prostate is approximately about 20g.[3] In adult male, benign prostatic hyperplasia (BPH) is a highly prevalent condition, 50% of male over 60 years having histologically proven prostatic hyperplasia while at least half reporting moderate to severe form of BPH. BPH causes vary symptoms from mild to severe obstructing symptoms depending on the size of gland and it also causes urinary tract infection. The surgical gold standard for the treatment of benign prostatic hyperplasia (BPH) is transurethral resection of the prostate (TURP) [4]. Preoperative morbidity for this procedure ranges in between 18% and 26% and the mortality rate maybe around 1% [5]. For the treatment of the prostate, a well-known drug Cialis (Tadalafil) is used.

Benign prostatic hyperplasia

During TURP significant hyponatremia occurs in about 11-41% of patients. The incidence of serum sodium level is less than 125 mEq after TURP which may reach approximately up to 15% with mortality rate of 40% [6]. During TURP through the prostatic venous sinuses some amount of irrigation fluid (20 ml/min to several L) is absorbed. While during  irrigantion penetration of about one liter irrigant in circulation for a period of 1 hour leads to an acute reduction in serum sodium concentration of 5–8 mmol/L, suggesting that there is a risk of hyponatrermic symptoms associated with absorption [7].  Acute hyponatremia that is low plasma sodium concentration (115–120 mEq/L) is a potentially serious condition [8].   Plasma hypo-osmolarity  and hyponatremia may result in intravascular hemolysis leading to increase in serum potassium [9].Early complications include urinary tract infection, prostatic capsule perforation, secondary haemorrhage and temporary urinary incontinence.[10] Other complications include electrolyte imbalance and hypervolemia called as TURP syndrome which are because of absorption of large quantities of the irrigating fluid [6] and results in hyponatremia, which can cause confusion, restlessness, tightness in chest, shortness of breath fatigue, irritability, nausea, headache, abdominal pain, bradycardia with hypertension, seizures and eventually coma.[11] There are different mechanisms that are involved in the development and progression of BPH. Although central implicated mechanism is ageing. The recent novel findings also highlighted the key role of metabolic syndrome, hormonal alterations and inflammation [12-14].

After TURP the assessment for serum electrolytes can prevent the patients from acquiring life threatening complications. The purpose of this study was to determine the correlation of serum sodium and potassium levels in BPH patients undergoing TURP before and after the surgery with respect to weight of resected tissue.

MATERIAL AND METHODS

A prospective observational study through non-probability convenient sampling technique was conducted at Department of Urology, Liaquat University of Medical and Health Sciences, Jamshoro,for a period of 7 months from January 2017 to July 2017. After informed consent, a total of 75 male patients aged 40-70years; presenting with benign prostatic hyperplasia undergoing transurethral resection of the prostate were included. Patients with previous unsuccessful surgery or recurrent strictures; with abnormal digital rectal examination or ultrasonography with suspicion of prostate cancer, history of prostate cancer, previous urethral or prostate surgery, urethral stricture, neurogenic bladder, bladder calculi, and patients on anticoagulant therapy were excluded. Blood samples were obtained before and after 24 hours of surgery for assessment. All patients underwent TURP under spinal anesthesia. Reports were assessed and mean changes in serum sodium and potassium were noted.

Data was analyzed using SPSS version 20.0. The quantitative variables i.e. age, BMI, duration of BPH, weight of resected tissue, baseline, postoperative and change in serum sodium and potassium levels were presented as mea and standard deviation. Pearson correlation was used to assess the association.  P-value of ≤0.05 was taken as significant.

RESULTS

In the total of 80 patients selected for this study, the mean age was 59.71 ± 7.13 years having a mean BMI of 21.99 ± 4.40 kg/m2. 6.92±1.16 days is the mean time during which patient remains symptomatic. The mean level of sodium before TURP was 141.60 ± 2.02 meq/L and after 24 hours of TURP was 140.44 ± 2.69 meq/L. The mean level of potassium before TURP was 4.29 ± 0.51 meq/L and after 24 hours of TURP was 4.65 ± 0.61 meq/L. The mean pre-operative haemoglobin level was about 13.92± 0.65 g/dl while the mean post-operative haemoglobin level was about 12.59± 0.91 g/dl. (Table:1). No correlation exist between baseline sodium level before resection (r=0.116 p=0.304) and 24 hours after the resection of prostate (r=0.219 p=0.051) with respect to weight of resected tissue. It was also observed that no correlation exist between baseline potassium level before resection (r=0.059 p=0.604) and 24 hours after the resection of prostate (r=-0.058 p=0.611) with respect to weight of resected tissue while moderate negative correlation (r=-0.310, p=0.005) exist between changes in potassium level with respect to weight of resected tissue. No correlation exist between exist between pre-operative hemoglobin level with respect to weight of resected tissue. (r=0.182 p=0.106). Moderate negative correlation (r=-0.309, p=0.005) exist between post-operative hemoglobin level with respect to weight of resected tissue. Strong positive correlation (r=0.690, p=0.001) exist in operative time with respect to weight of resected tissue. (Table:2)

 

Table 1: Baseline descriptive statistics of patients undergoing surgery

 

Variables Mean St Dev
Age (years) 59.71 7.13
BMI(kg/m2) 21.99 4.40
Duration of Symptoms(days) 6.92 1.16
Weight of resected Tissue (gram) 44.43 7.84
Operative Time in (Minutes) 64 11.09
Sodium

(meq/L)

Baseline 141.60 2.02
After 24 hours 140.44 2.69
Change -1.16 2.06
Potassium

(meq/L)

Baseline 4.29 0.51
After 24 hours 4.65 0.61
Change 0.35 0.21
Hemoglobin

(g/dl)

Pre-operative 13.92 0.65
Postoperative 12.59 0.91

 

Table 2: Correlation of electrolyte imbalance before and after the surgery with weight of resected tissue.

 

Variables Weight of resected tissue
r p-value
Sodium (meq/l) Baseline 0.116 0.304
After 24 hours 0.219 0.051
Change 0.172 0.127
Potassium (meq/l) Baseline 0.059 0.604
After 24 hours -.058 0.611
Change -.310** 0.005
Hemoglobin (gm/dL) Pre operative 0.182 0.106
Post operative -.309** 0.005
Operative Time in (minutes) .690** <.001

DISCUSSION

80 patients undergoing TURP were being selected for our study. The results of our study showed that levels of sodium before and after 24 hours of TURP (p-value 0.127) did not show considerable difference while substantial difference in the levels of potassium before and after 24 hours of TURP (p-value-0.005) was noted. Significant changes in potassium were observed post-operatively in which mean potassium level before and after the resection was 4.29±0.51 and 4.65±0.61 respectively with the increase of about 0.35±0.2 meq/l and moderate negative correlation exist between change in potassium level (r=-0.310, p=0.005). One of the study carried by Altaf J et al. in which they select 150 patients undergoing TURP, 93 patients (62%) were found to have no electrolyte imbalance while 57 patients (38%) were noted to have disturbance in their electrolytes. Substantial mean preoperative and postoperative hypokalemia was reported (2.82 ± 0.5) mmol/L and (3.8 ± 1.6) mmol/L (p-value 0.03). [15] In our study changes in sodium levels were observed post-operatively in which mean sodium level before and after the resection was 141.60± 2.02 and 140.44±2.69 respectively with the decrease of about 1.16±2.06 meq/l and no correlation exist between change in sodium level. In study by Karadeniz MS et al., among 52 TURP patients, significant difference was found in sodium levels of patients undergoing monophasic TURP (p-value 0.001) while no substantial difference was seen in sodium levels of patients undergoing biphasic TURP (p-value 0.59). Most of the patients did not have significant levels of change in potassium levels either undergoing monophasic (p-value 0.87) or biphasic (p-value 0.82) TURP [16] Another study carried by Aziz W et al., it was reported that out of total of 280 TURP patients significant change in the electrolyte levels were present among 66 (23.5 %) patients (p-value 0.001 for sodium and 0.002 for potassium). [17]  In one of the study carried by Desai A et al., it was documented that non-significant changes in levels of sodium and potassium, pre and post-operative were found (p-value 0.38 and 0.58) respectively. [18] The basis for the beginning of TURP syndrome has been assumed to be water intoxication with hyponatremia. Because of continuous irrigation during

TURP fluid absorption from venous channels in prostatic bed occur. Absorption of this fluid leads to changes in serum electrolytes and potentially can lead to clinical TURP syndrome. Provided that the irrigation fluid column is kept at a constant height, a constant volume of fluid is obtained per minute during resection. [19] However, the amount of fluid that is absorbed not only depends on the number of prostatic venous sinuses opened  but also on duration of exposure of the exposed venous sinuses to the irrigating fluid and also upon and hydrostatic pressure at the prostatic bed. There are a number of strategies have been proposed to diminish the risk of fluid absorption during TURP, but almost none is capable of eliminating this complication altogether. One of the proposed study suggested to keep resection time below 60 min to minimize fluid absorption; TURP syndrome has been reported after a resection time of only 15min. [20] In order to do fluid balance in every patient, monitoring extent of fluid absorption during surgery has been suggested to. Newer techniques, such as bipolar resectoscopes and vaporizing the tissue instead of resecting tissue, have reduced fluid absorption and its consequent electrolyte derangement, so routine monitoring of fluid absorption has been largely abandoned outside a study setting. However there is no consensus on routine monitoring of postoperative electrolytes. It has been suggested that with improvements in technology and use of isotonic, non hemolytic solutions; electrolyte derangement is rare. Particularly with the use of isotonic saline and bipolar resection TURP syndrome is of historical interest only.[21]

Monitoring of electrolytes should be considered in patients having risk factors for increased fluid absorption.  The mixed approach of our study has assured that we have sampled the extensive range of patients undergoing transurethral resection. However, the study might not be immune from practice and observer bias. Considering the findings of our study and to what range these observations are consistent with the hemodynamic variables of the patient would be revealing to discover more facts about the electrolyte balance in these patients.

CONCLUSION:

The results of our study predicted that electrolyte derangement after transurethral resection of the prostate in benign prostatic hyperplasia is frequent. It was further revealed that moderate negative correlation exists between changes in potassium level and post operative heamoglobin level and strong positive correlation exists in operative time with respect to weight of resected tissue. However no significant correlation exist in the sodium levels.

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By Dr. Ravi Mootha, M.D. On: May 07, 2019 at 20:13:39