Abstract
Objectives:
Postoperative urinary retention (POUR) is influenced by many factors, and its reported incidence rate varies widely. This study aimed to investigate the occurrence and risk factors for urinary retention following general anesthesia for endoscopic nasal surgery in male patients aged >60 years.
Methods:
A retrospective review of medical records between January 2015 and December 2019 identified 253 patients for inclusion in our study. Age, body mass index (BMI), a history of diabetes/hypertension, American Society of Anesthesiologists (ASA) classification, and urologic history were included as patient-related factors. Urologic history was subdivided into 3 groups according to history of benign prostate hyperplasia (BPH)/lower urinary tract symptoms (LUTS) and current medication. The following was analyzed as perioperative variables for POUR development: duration of anesthesia and surgery; amount of fluid administered; rate of fluid administration; intraoperative requirement for fentanyl, ephedrine, and dexamethasone; postoperative pain; and analgesic use. Preoperatively measured prostate size and uroflowmetry parameters of patients on medication for symptoms were compared according to the incidence of urinary retention.
Results:
Thirty-seven (15.7%) patients developed POUR. Age (71.4 vs 69.6 years), BMI (23.9 vs 24.9 kg/m2), a history of diabetes/hypertension, ASA classification, and perioperative variables were not significantly different between patients with and without POUR. Only urologic history was identified as a factor affecting the occurrence of POUR (P = .03). The incidence rate among patients without urologic issues was 5.9%, whereas that among patients with BPH/LUTS history was 19.8%. Among patients taking medication for symptoms, the maximal and average velocity of urine flow were significantly lower in patients with POUR.
Conclusions:
General anesthesia for endoscopic nasal surgery may be a potent trigger for urinary retention in male patients aged >60 years. The patient’s urological history and urinary conditions appear to affect the occurrence of POUR.
Keywords
Introduction
Postoperative urinary retention (POUR) is the inability to void, despite a distended bladder, in the early period following anesthesia and surgery. The criteria for defining POUR differ between studies and depend on the diagnostic methods used. 1,2
Multiple factors have been studied as variables influencing the development of POUR, including age, gender, a history of lower urinary tract symptoms (LUTS), underlying diseases, the type and duration of anesthesia and surgery, the amount of fluid administered, the use of narcotic analgesics, and urine volume in the bladder in the post-anesthesia care unit. 1 -4 Due to the heterogeneous nature of the disease and multifactorial causes, a wide range of incidence rates have been reported (0.37%-75%). 5,6 The causes of POUR can be largely divided into patient-, anesthesia-, and surgery-related factors. Among patient-related factors, age and LUTS history (eg, frequency, urgency, straining, weak stream) have been studied as important contributors to POUR. In a recent meta analysis, older age and a history of LUTS increased the risk of POUR 2.11- and 2.83-fold, respectively. 1 In men, LUTS is mainly associated with benign prostate hyperplasia (BPH), and its prevalence is known to increase with age; it has been shown that 50% to 55% of men aged ≥50 years are affected by BPH/LUTS, compared to 80% in those aged ≥70 years. 7
Regarding anesthetic technique, general anesthesia is associated with a lower incidence of POUR than spinal anesthesia, which blocks the sacral micturition reflex. Anesthetics cause contraction failure of the bladder by relaxing smooth muscle or restraining autoregulation of the detrusor muscle. 8,9
With regard to the surgical procedure, POUR is commoner following anorectal surgery and orthopedic joint replacements compared to other forms of surgery and, in cases of abdominal surgery, is commoner with laparoscopic than with open surgery. Direct irritation of the urinary system during surgery can increase obstructive tension or swelling of the bladder outlet, as well as dysfunction of bladder contraction due to organ traction and displacement, long operation times, and a high fluid requirement. Therefore, the surgeon’s proficiency is an independent factor for POUR development. 3,10 -12
This study aimed to investigate the factors affecting the incidence of urinary retention following general anesthesia for endoscopic nasal surgery in elderly male patients. Since endoscopic nasal surgery employs a transnasal approach making skin incision unnecessary, has little effect on abdominal and pelvic organs, and has a relatively wide range of perioperative variables, the effect of general anesthesia on POUR may be evaluated better in patients undergoing this surgery. To our knowledge, the effect of general anesthesia during endoscopic nasal surgery on POUR has not been previously investigated.
Patients and Methods
Patient Selection
This study was approved by the institutional review board of the Veterans Health Service Daejeon Hospital (reference number: VHSDJ-01-2020-0011) and complies with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
We retrospectively reviewed the medical records of patients undergoing surgery at our otorhinolaryngology department between January 2015 and December 2019. Among them, men aged older than 60 years, who underwent endoscopic sinus surgery and septoplasty under general anesthesia, were selected as participants. Skin incisions, in addition to an endoscopic approach or other surgical procedures, may affect the postoperative course due to the need for additional pain or wound management. To ensure a homogenous set of patients and evaluate POUR appropriately, we excluded patients: (1) undergoing surgery on sites other than the paranasal sinuses and nasal cavities, (2) undergoing skin incisions in addition to the endoscopic approach, (3) requiring periodic catheterization, (4) receiving preoperative indwelling catheters or intraoperative intermittent catheterization, and (5) receiving radical surgery and radiotherapy for prostate cancer.
Covariates and Outcomes
The investigated patient-related factors included age, body mass index (BMI), use of medications for diabetes and hypertension, American Society of Anesthesiologists (ASA) classification, and urological medical history. BPH/LUTS history was determined by reviewing all available urologic data. This included clinical presentations, symptom severity using an International Prostate Symptom Score, physical examinations, measured prostate size, blood tests such as prostate-specific antigen, uroflowmetry, and treatment methods. Patients were divided into 3 groups according to their urology history: no history of BPH/LUTS (urologic history [UH] 1); a history of BPH/LUTS and having received prior treatment, but not receiving treatment at the time of surgery (UH 2); and receiving treatment for BPH/LUTS (UH 3).
UH 2 patients were evaluated based on their last visit to the urology department for BPH/LUTS. For patients in UH 3, we confirmed the medication prescribed at the time of operation for BPH/LUTS at the urology department. We investigated the available data of patients with a UH, including the examinations performed within 1 year before surgery; this included the size of the prostate measured by transrectal ultrasound and uroflowmetry parameters including maximal flow rate (Qmax), average flow rate (Qavg), voided urine volume (VV, which should be >150 mL), and postvoiding residual urine (PVRU). Investigated variables related to anesthesia and surgery included the duration of anesthesia and surgery; total amount of fluid administered; rate of fluid administration; and the intraoperative requirement for fentanyl, ephedrine, and dexamethasone. Pain was assessed using the Visual Analog Scale (VAS), and intravenous analgesic administration was recorded postoperatively in the wards.
The duration of anesthesia was the time from when the anesthesiologist first treated the surgical patient to when the patient left the operating room. The duration of surgery was the time from the endoscopic inspection of the nasal cavity to when intranasal packing was performed.
Patients who experienced postoperative voiding difficulties were investigated. Among them, those who underwent catheterization for urination, despite suprapubic distension accompanied with pain or discomfort postoperatively, were defined as POUR cases.
Statistical Analysis
Continuous variables are expressed as means ± standard deviation and P values were calculated using Student t test. Normality tests were performed using the Shapiro-Wilk test; the Mann Whitney U test was used if normality was not satisfied. Categorical variables were denoted by frequency and percentages, and P values were calculated using the chi-square or Fisher exact tests. On univariate analyses, variables with a P value of <.1 were considered independent variables during multiple logistic regression. Multiple logistic regression was used to identify the significant risk factors for POUR. Associations between risk factors and POUR were summarized using odds ratios (OR) and 95% CI. All statistical analyses were conducted using the R Statistical Package, Version 4.0.1 (R Foundation for Statistical Computing), and a P value of <.05 was considered statistically significant.
Results
Patient Characteristics
This study included a total of 235 patients. The demographic data and perioperative variables are presented in Table 1.
Demographic Data and Perioperative Parameters of Patients.a
Abbreviations: ASA = American Society of Anesthesiologists; N, number of patients; UH, urologic history; VAS, Visual Analog Scale.
a Data are expressed as mean ± SD or frequency (percentage of population).
Considering patients by UH, 68 (28.9%) patients had no history of BPH/LUTS (UH 1); 46 (19.6%) patients had a history of BPH/LUTS and had received prior treatment, but were no longer receiving treatment at the time of operation (UH 2); and 121 (51.5%) patients were currently receiving treatment for BPH/LUTS (UH 3). UH 2 included 1 patient who had undergone transurethral resection (TUR) of the prostate 10 years previously. UH 3 included 1 patient who had undergone TUR of the prostate 9 years previously.
For general anesthesia, propofol and desflurane were used for induction and maintenance of anesthesia, respectively. Rocuronium was used for muscle relaxation, and pyridostigmine with atropine and/or glycopyrrolate were used as reversal agents. In 13 cases, intravenous fentanyl was used during maintenance. Ephedrine was used as a vasopressor in 69 patients during anesthesia. Dexamethasone was used in 46 cases on request of the anesthetic or surgical teams. No patients required blood transfusion during surgery and normal saline or balanced crystalloids were used as maintenance fluids.
In the ward, all patients were encouraged to urinate with sufficient time prior to surgery. Postoperatively, the pain score of the surgical site was assessed using the VAS and averaged 2.9 ± 1.9 (range 0-8). Eighty nine (37.9%) patients received paracetamol or ketorolac for pain control; no narcotic analgesics were administered.
Incidence of Urinary Retention and Outcomes
Among the 235 patients, 50 (21.3%) complained of urinary difficulty including hesitation, frequency of urination, and a sense of incomplete bladder emptying. Although 13 patients successfully urinated using conservative methods, such as the application of a hot pack, 37 (15.7%) patients required catheterization due to suprapubic distension accompanied by pain and discomfort; these patients comprised the POUR group. Of these 37 patients, 25 did not develop further urinary retention following a single episode of catheterization, while 12 were treated more than twice. Among them, 5 were treated with an indwelling catheter (1 in UH 2; 4 in UH 3). Among the 37 patients with POUR, 35 received catheterization as no spontaneous urination was possible postoperatively; 2 patients in UH 3 were able to urinate initially, but subsequently required catheterization for urinary retention. The average volume collected during catheterization was 682.1 ± 213.1 mL (range 400-1200 mL). Medications were started or changed in patients in the POUR group who received catheterization, based on urological consultation.
The patients with POUR and the remaining 198 patients without POUR were compared statistically (Table 2). On univariate analyses, only the presence of UH was significantly associated with POUR (P = .03). On multiple logistic regression, which included age, BMI, and UH as variables, only UH was associated with significance (Table 3); the incidence in the UH 1, UH 2, and UH 3 groups was 5.9% (4/68), 19.6% (9/46), and 19.8% (24/121), respectively (Figure 1). Compared with UH 1, the OR in UH 2 was 3.93 (95% CI: 1.18-15.18, P = .04), and that in UH 3 was 4.61 (95% CI: 1.45 13.94, P = .008).
Perioperative Variables in Patients Who Did and Did Not Develop Postoperative Urinary Retention.a
Abbreviations: ASA, American Society of Anesthesiologists; N, number of patients; POUR, postoperative urinary retention; SD, standard deviation; UH, urologic history; VAS, visual analog scale.
a Data are expressed as mean ± SD or frequency (percentage of population).
Logistic Regression Analysis With Urinary Retention Requiring Catheterization as the Dependent Variable.
Abbreviations: BMI, body mass index (kg/m2); OR, odds ratio; UH, urologic history.
Comparison of the incidence rate of catheterization for urinary retention following general anesthesia for endoscopic nasal surgery. Patients are grouped according to their urologic history. POUR indicates postoperative urinary retention; UH, urologic history. *P < .05, **P < .01.
Among 46 patients in UH 2, the reasons for discontinuing medication included perceived improvement of symptoms (11 patients), low compliance (4 patients), and side effects such as incontinence (2 patients); the reasons were undetermined in 29 patients. On average, the last time that patients in UH 2 visited the urology department was 36.9 ± 34.0 months previously (range 2-120 months). In patients with and without POUR, the interval was 45.3 ± 38.9 months and 34.8 ± 33.0 months, respectively, without significant difference (P = .38).
All patients in UH 3 were taking an α-blocker, 31 of whom were concurrently taking a 5α-reductase inhibitor. Additionally, imipramine, propiverine, mirabegron, and desmopressin were administered in 5, 5, 8, and 3 patients, respectively, for symptoms of an overactive bladder and nocturia. Confirming the prostate size with rectal ultrasound was possible in 84 patients (18 with POUR, 66 without POUR), and the prostate size was not significantly different between the groups (POUR: 32.3 ± 19.0 mL vs without POUR: 34.3 ± 13.7 mL, P = .18).
Uroflowmetry parameters and the time interval between the uroflowmetry assessment and the operation were compared between the patients in UH 3 with (N = 10) and without POUR (N = 49; Table 4). In patients with POUR, the Qmax and Qavg were lower than in those without (P = .02). There was no significant difference between the 2 groups regarding the VV, PVRU, or time interval.
Comparison Between Parameters of Preoperative Uroflowmetry of Patients in Group 3.
Abbreviations: N, number of patients; POUR, postoperative urinary retention; PVRU, postvoiding residual urine volume; Qavg, the average urine flow rate; Qmax, the maximal urine flow rate; TI, time interval between examination of uroflowmetry and operation; VV, voided urine volume.
Discussion
According to the expected levels of postoperative pain, endoscopic nasal surgery is classified as an intermediate operation, similar to herniorrhaphy and total hip replacement. 13 Postoperative urinary retention after otorhinolaryngologic surgery has been rarely studied due to the relatively low incidence rate compared to abdominal and orthopedic surgery. However, there are some advantages of using otorhinolaryngologic surgery to help understand the incidence of POUR. Endoscopic nasal surgery is a conservative operation and is not likely to directly affect the urinary system. It also includes a relatively wide range of durations of anesthesia and surgery and total amounts and rates of fluid administration. Therefore, our study could help understand the relationship between general anesthesia and the occurrence of POUR and examine POUR that occurs after intermediate surgeries, particularly in elderly men.
Although the mechanism is very complex, micturition refers to the act of passing urine with a force exceeding the existing resistance. Causes of urinary retention can be divided into obstruction of the bladder outlet, disruption of sensory and motor innervations, and myogenic failure due to bladder overdistention. 3 Among the factors related to anesthesia and surgery, those that could increase resistance or weaken the force of excretion can cause urinary retention.
Ephedrine is one of the most widely used vasopressor drugs during anesthesia, with a half-life of approximately 3 to 6 hours; it causes nonselective α- and β-receptor stimulation. 14 Since it is well recognized as a cause of acute urinary obstruction and was used by 69 (29.4%) elderly males in this study, it is possibly linked to POUR; however, univariate analysis found no statistical significance. Moreover, dexamethasone, which is reported to reduce swelling of the bladder outlet and prostate in hernia surgery and could lower the incidence of POUR, did not exhibit any meaningful effects in this study. 15 The postoperative pain score, which is related to increased sympathetic tone, also showed no effects. 16
Narcotic analgesics, an overfilled bladder due to the excessive infusion of fluids, and general anesthetics and anticholinergics contribute to the reduction or failure of bladder contraction. 3,4,17 -19 Fentanyl was administered intravenously to 13 patients during anesthesia; there was no difference in the incidence of POUR owing to its use. Additionally, the duration of anesthesia and surgery and the total amount of fluid administered, known factors directly related to bladder overfilling, were not found to be related to POUR. Higher rates of fluid administration per weight are believed to result in bladder overload over a relatively short duration, with sufficient fluid volumes to avoid POUR; however, there was no statistical difference between patients with and without POUR.
General anesthetics and anticholinergic drugs, such as atropine and glycopyrrolate in combination with pyridostigmine, were administered to all patients. Although these agents could not be used as variables for analysis, it may be assumed that they play an important role in causing POUR, since patients in this study were aged >60 years and had pre-existing reductions in bladder function due to degenerative changes in nerves and muscles. 1,4
Here, the only variable associated with urinary retention following general anesthesia for endoscopic nasal surgery was the urological history. The incidence rate of POUR in patients who did not experience BPH/LUTS was 5.9%, whereas that in patients who had BPH/LUTS was 19.8%. In general, the overall rate of acute urinary retention in men without risk factors, or those who never experienced acute urinary retention, is approximately 2.2 to 8.5/1000. In contrast, the incidence rate in men who have BPH/LUTS or have experienced acute urinary obstruction is 18.3 to 35.9/1000. 20,21 The extent to which medical therapy reduces the rate of acute urinary obstruction in patients with BPH/LUTS remains unclear. Depending on the type and duration of the medications taken, some studies have found that medical treatment does not lower the incidence of acute urinary obstruction compared to a placebo; however, certain studies have reported the relative risk reduction in the treatment group to be 79% to 85%. 22
Prophylactic administration of an α-blocker has been shown to lower the incidence of POUR. 23,24 It has been reported to reduce the incidence of POUR in patients without urologic problems after hernia surgery; however, it does not lower the incidence rate when used for 7 days in patients undergoing surgery for rectal cancer.
In this study, incidence rates were significantly different between patients without a history of BPH/LUTS (UH 1) and UH 2 patients (P < .05) and UH 3 patients (P < .01). Additionally, although this analysis used limited data, a difference was found in the Qmax and Qavg measured preoperatively in patients in UH 3 with and without POUR. Uroflowmetry is a noninvasive diagnostic test that measures the urine flow over time. There are numerous interpretation methods, and Qmax is one of the most commonly used indicators. Depending on the patient’s age and gender, a Qmax of <15 mL/s is accepted to be decreased in men, indicating a possible obstruction or abnormal bladder contraction. 25 It is reported that acute urinary obstruction is 3.9-fold more common when the Qmax is ≤12 in men aged 40 to 70 years. 26
In this study, Qmax and Qavg on the uroflowmetry performed within 1 year preoperatively in patients receiving urology treatment were significantly higher in patients without POUR. However, this was a retrospective study, and there are limitations; these test results do not reflect the immediate condition before surgery and did not include all patients in UH 3. It is believed that restoration of urinary conditions through appropriate treatment is important for preventing POUR following general anesthesia in elderly male patients.
The average BMI of patients with POUR was slightly lower than that of patients without POUR; however, there was no significant difference between the 2 groups. Obesity is strongly associated with BPH/LUTS and prostate inflammation; however, its relationship with POUR is obscure. 27 The mean BMI was significantly lower in patients with POUR in a study of male patients aged >55 years who had undergone colorectal surgery and that of women undergoing laparoscopic cholecystectomy. 28,29 Furthermore, another study has shown that the time to first spontaneous urination is delayed in patients with a lower BMI after spinal anesthesia. 30 Therefore, further research is needed to better understand the POUR development in patients who are underweight or have a weight in the low range of normal.
The overall incidence of POUR in this study was 15.7%. There are few studies regarding POUR in the field of otorhinolaryngology. In a study of 70 patients aged >70 years who underwent general anesthesia for cochlear implants, 1 male patient with BPH had POUR requiring indwelling catheterization as an anesthetic complication. 31 In addition, among 16 709 adult patients with an average age of 50.3 years (54.2% female) who underwent ambulatory otologic surgery, the most common cause for revisits was urinary retention/urinary tract infection, which occurred in 93 (0.56%) patients. 32 The reason for the higher incidence rate of POUR in this study could be that the present study included elderly men alone, who are known to be prone to POUR. Considering that POUR after general anesthesia can occur in 0% to 24.7% of patients who undergo intermediate abdominal surgery, including appendicectomy and herniorrhaphy, mastectomy, thyroidectomy, and varicose vein surgery, it appears that POUR is not uncommon and warrants attention after general anesthesia for endoscopic nasal surgery in elderly male patients. 3,4
Despite all our efforts, there are clear limitations to this retrospective study. Although this study recruited patients who underwent surgery over a period of 5 years, few patients were included. Therefore, the power based on the univariate analysis was not very high. The power was calculated between the variables and the incidence of POUR, and all were found to be low; the power for UH, BMI, intraoperative fentanyl use, diabetes treatment, and the remaining variables was 66%, 50%, 29%, 25%, and <20%, respectively. Although some patients were diagnosed with Parkinson disease or transient ischemic attacks, the numbers were negligible and therefore not included in the analysis. Although the ASA classification partially reflects the state of these neurological diseases, these variables need to be re-evaluated in future large-scale studies. In this retrospective study, we analyzed the uroflowmetry data of some patients in UH 3; however, a large-scale prospective study may obtain more meaningful results by measuring and analyzing all patients’ preoperative uroflowmetry data. Furthermore, it is necessary to investigate the relationship between the occurrence of POUR and the type of medication taken by the patients, namely, α blockers alone or combined with a 5α-reductase inhibitor and/or agents for an overactive bladder (eg, imipramine, propiverine, mirabegron).
Conclusions
Our findings show that general anesthesia may be a potent trigger for POUR in elderly male patients. Moreover, the incidence of POUR varied according to urological history, occurring in 5.9% of patients without BPH/LUTS compared to 19.6% of those who have previously experienced BPH/LUTS symptoms and 19.8% of those taking medications for such symptoms during the study period.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by a VHS Medical Center Research Grant, Republic of Korea (grant number: VHSMC 20013). The authors would like to thank Biostatistician Young Lee, VHS Medical Research Center, for invaluable help with statistical analysis.
