Iopamidol Classification Essay

Abstract

The present study aims to evaluate the diagnostic value of four-dimensional CT angiography (4D-CTA) in the diagnosis of arterial erectile dysfunction (ED) using 320-detector row dynamic volume CT. Arterial ED patients attributed to arterial insufficiency were enrolled. To induce penile erection, an intracavernous injection (ICI) of corpus cavernosum with a vasoactive drug was administered. Patients were assigned into the erection hardness score (EHS) 1/2 group or EHS 3/4 group. Color duplex Doppler ultrasound (CDDU) was used to analyze blood flow spectrum. Each patient was examined using 4D-CTA. Receiver operating characteristic (ROC) curve was plotted to evaluate the diagnostic value of 4D-CTA in arterial ED. According to Irwin Goldstein, the EHS 3/4 group (n=38) had a shorter course of ED and low proportion with history of hypertension, hyperlipidemia, and diabetes than the EHS 1/2 group (n=35). The peak systolic velocity (PSV), end diastolic velocity (EDV), and resistant index (RI) in the EHS 3/4 group were lower than those of the EHS 1/2 group. 4D-CTA showed there were a total of 35 cases in the EHS 1/2 group (two cases missed) and 38 cases in the EHS 3/4 group (seven cases misdiagnosed). Using 4D-CTA to diagnose arterial ED, the area under the ROC curve yielded a value of 0.879, with a specificity of 93.9% and a sensitivity of 82.5%. These findings indicated that 4D-CTA using 320-detector row dynamic volume CT is a promising and reliable utility in diagnosing arterial ED.

  • Arterial erectile dysfunction
  • Diagnosis
  • 320-row dynamic volume CT
  • Four-dimensional CT angiography
  • Specificity
  • Sensitivity

Introduction

Erectile dysfunction (ED) is defined as the inability to reach potential or maintain a full erection required for satisfying sexual performance [1]. It has been estimated that the worldwide prevalence of ED will be 322 million cases by the end of 2025 [2]. ED is multifactorial and the causes may include neurogenic disorders, cavernosal disorders (peyronie’s disease), psychological disorders (performance anxiety, stress, and mental disorders), surgery, and aging [3–7]. As for the diagnosis of ED, color duplex Doppler ultrasound (CDDU) is of great significance in identifying the most appropriate therapy [8]. However, poor reproducibility is considered as the main bias of penile artery dynamic Doppler examination, and psychological issues are considered to be mainly responsible for the aforementioned [9]. Furthermore, due to lack of standardized measures, it is difficult to obtain accurate clinical diagnosis of a patient undergoing hemodynamic assessment of the penis by CDDU [8]. In addition, due to the complexity of ED and inadequate availability of studies, there are still many limitations to our understanding of ED [10].

The 320-detector row dynamic volume CT consisting of 320-slice detectors that cover a width range of 16 cm along the z-axis, 0.5 m of the thickness, and 350 ms of gantry rotation time, which reliably provides high diagnostic accuracy without heart rate/rhythm control [11]. Making it possible to accurately image the flow of contrast in the cerebral vasculature by conducting consecutive volumetric scans over a predetermined time frame: this type of time-saving CT can be applied to estimate the hemodynamics, as well as the morphology, of various cerebrovascular conditions [12]. Originating in CT perfusion (CT), four-dimensional CT angiography (4D-CTA) has been classified as noninvasive and is better at estimating the collateral status [13]. During the past few decades, 4D-CTA using 320-detector row dynamic volume CT has been the attention of researchers in the diagnosis of diseases such as atherosclerosis causing myocardial ischemia, vascular clips or endovascular coils, and developmental venous anomalies [14–16]. Its characteristic findings have been of great importance in evaluating the disease severity and in monitoring response to treatment [17]. Therefore, the present study was designed to investigate the diagnostic value of 4D-CTA in the diagnosis of arterial ED using 320-detector row dynamic volume CT.

Materials and methods

Study subjects

A total of 73 patients (the age range was 19–52 years old with mean age of 30.3 ± 5.8 years, and course of disease ranged from 2 to 96 months) admitted in the Ningbo First Hospital with arterial ED for the first time between the period of March, 2014 to March, 2016 were enrolled for this study. The inclusion criteria were as follows: patients had low or no erection ability as tested by nocturnal penile tumescence (NPT) and audiovisual sexual stimulation (AVSS); arterial ED patients diagnosed by CDDU with peak systolic velocity (PSV) < 35 cm/s (when PSV is lower than 35 cm/sec in young patients, it is mainly due to psychological causes) [18]. Exclusion criteria: patients with traumatic injuries of the penis, spinal cord injury, or long-term use of drugs known to affect sexual function. The study performed with approval of the Ethical Committee of Ningbo First Hospital and the participating patients signed informal consents.

NTP and AVSS evaluation

NTP: The patients were requested to undergo examination in the examination room alone. The portable RigiScan was put on the patients at 21:00 every night, and were taken out at 8:00 the next day, the examination was conducted for three nights. Next, the data were recorded.

AVSS: The patients were requested to stay in special examination room (quiet and avoiding light), and watch erotic videos for 45 min. The RigiScan was used to record erection hardness, and the data were analyzed [19].

Clinical history and physical examination

Blood samples were withdrawn from all fasting patients in the morning. Serum biochemistry was used to test blood glucose and lipids. All men had a detailed consultation and physical examination, with special attention to relevant history of masturbation, diabetes, hypertension, hyperlipidemia, and angiocardiopathy. The patients also received evaluations scores for Self-rating Anxiety Scale (SAS) [20] and Self-rating Depression Scale (SDS) [21].

Inducing erection with intracavernous injection

After intracavernous injection (ICI) for inducing erection, patients were positioned in a supine position. A constriction ring was placed on the root of the penis to prevent venous return. A combination of papaverine (30 mg) and phentolamine (1 mg) was injected into cavernosa after disinfection. After compressing the penis for 3–5 min, the penile deep arteries and cavernosal arteries were bidimensionally observed before and after injecting. According to Irwin Goldstein, there were four erection hardness levels: level I: not hard or no erection; level II: hard but not hard enough for penetration; level III: hard enough for penetration but not completely hard; level IV: completely hard and fully rigid. The four levels were assigned into Erection Hardness Score (EHS) 1/2 group (level I and level II ) and EHS 3/4 group (level III and level IV) [22].

Color duplex Doppler ultrasound

A CDDU machine (Biosound-AU4, America) with ultrasonic probe frequency of 13 MHz and the color Doppler probe frequency of 7 MHz was used. The ultrasonic transducer was placed on the root of penis. The color Doppler probe was employed to detect blood flow level in the blood vessels after ICI and to measure the perimeter and length of the penis, with the angle of sampling ultrasonic beam and vessel diameter not greater than 60°. Spectrum of blood flow was obtained and analyzed. Vascular examination was performed to record the PSV, end diastolic velocity (EDV), and resistant index (RI).

Four-dimensional CT angiography

Iodine allergy was tested 30 min before angiography. A combination of papaverine (30 mg) and phentolamine (1 mg) was injected into the cavernosa to induce an erection. After 3–5 min of compression on the injection point, patients were positioned in a supine position and indirect CTA was performed. Hundred milliliters (350 mgI/ml) of nonionic iodinated contrast agent was intravenously injected with a high pressure injector at a flow rate of 4 ml/s. Efforts were made to ensure that the scan coverage was ranging from the internal iliac artery to the root of the penis. Dynamic volume CT scanning was employed via 320-detector row dynamic volume CT (Toshiba Aquilion One; Toshiba Corporation, Kawasaki, Japan) with the following parameters: rotation speed of the ball tube 0.35 s/rot, slice thickness 1.5 mm, coverage area 16 cm, and field of view (FOV) 240 mm. The 65 ml (370 mgI/ml) of nonionic contrast agent iopamidol was intravenously injected at a rate of 5.0 ml/s, followed by 30 ml of normal saline at the same rate. After a 7 s delay post-injection, CT scanning was performed for 50–60 s.

All the images were reconstructed with 0.5 mm slice thickness. Each volume data contained 320 images, and 3200 images were recorded from each examination. Next, the data were imported to four-dimensional digital subtraction angiography (DSA) for acquiring four-dimensional dynamic vascular images. Multiple planar reformation (MPR), maximum intensity projection (MIP), and volume rendering (VR) were performed to visualize the penis. Patients with lesions in internal artery and/or cavernosal arteries, stenosis or no development in the dorsal artery of the penis were assigned to the EHS 1/2 group.

Statistical analysis

Data were analyzed using the statistical package for the social sciences (SPSS) version 21.0 (SPSS Inc., Chicago, IL, U.S.A.). The t-test was used for comparison between two groups of measurement data. The measurement data were recorded as mean ± standard deviation (SD). Measurement data were expressed as percentage and rate, and were analyzed using chi-square test. ROC curve was applied to quantify the diagnostic value of 4D-CTA for arterial ED patients. P<0.05 was regarded as statistically significant.

Results

Baseline characteristics of arterial ED patients

Among the 73 ICI induced arterial ED patients, level I included 13 patients, level II had 22 patients, and level III had 9 patients, whereas level IV had 29 patients. According to Irwin Goldstein, the EHS 1/2 group contained 35 cases while the EHS 3/4 group consisted of 38 cases. Table 1 shows the detailed baseline characteristics of the subjects. No significant differences were observed in terms of age, anxiety, and depression between the two groups. Notably, the EHS 3/4 group experienced the condition for a shorter duration and had less cases with any prior history of hypertension, hyperlipidemia, diabetes, and masturbation than the EHS 1/2 group (all P<0.05).

Table 1Baseline characteristics of 73 arterial ED patients

Color duplex Doppler ultrasound scanning of arterial ED patients

Arterial ED patients in the EHS 1/2 group (n=35) had a single-peak spectrum in systole with no or a rather low blood flow spectrum in diastole (Figure 1A). Arterial ED patients in the EHS 3/4 group (n=38) had a greater blood flow spectrum in both systole and diastole after erection (Figure 1B). The EHS 3/4 group had lower PSV, EDV, and RI than the EHS 1/2 group (all P<0.05) (Table 2).

Figure 1Color duplex Doppler ultrasound scanning of arterial ED patients in the EHS 1/2 (A) and EHS 3/4 (B) groups
Table 2Comparisons of CDDU parameters between the EHS 1/2 group and the EHS 3/4 group

Four-dimensional CT angiography of arterial ED patients

The 4D-CTA showed that among the 35 arterial ED patients in the EHS 1/2 group, two cases were missed diagnosis, and there were nine cases with lesions in internal carotid artery, 14 cases in cavernous artery, five cases in penile dorsal artery, and five cases in internal carotid vein, with obvious stenosis or no development compared with the normal contralateral artery (Figure 2A). Among 38 arterial ED patients in the EHS 3/4 group, there were seven cases of misdiagnosis. The Figure 2(B) showed internal carotid artery, cavernous artery, and penile dorsal artery, with contrast agent filling and no obvious artery stenosis or development. The results proved that 4D-CTA could display the cavernous artery, internal carotid artery, and penile dorsal artery simultaneously, thereby clearly identifying lesion sites.

Figure 2Four-dimensional CT angiography of arterial ED patients in the EHS 1/2 (A) and EHS 3/4 (B) groups

Evaluating the diagnostic value of 4D-CTA in patients with arterial ED using ROC curve

Compared with the ‘Gold Standard’ of CDDU, area under the ROC curve (AUC) of 4D-CTA for the diagnosis of arterial ED was 0.879, with a specificity of 93.9%, a sensitivity of 82.5%, positive predictive value of 94.3%, negative predictive value of 81.6%, and diagnostic accuracy of 87.7%. The accuracy of 4D-CTA in diagnosing arterial ED was comparable to that of CDDU (Figure 3).

Figure 3Evaluation of the diagnostic value of 4D-CTA in patients with arterial ED using ROC curve

Discussion

It has been reported that CDDU may aid in the decision-making process regarding choosing the most appropriate and right therapy for treating ED. Unfortunately, there is no uniform standardization in performing CDDU resulting in high variability in data expression and interpretation while comparing results among various centers, especially when conducting multicenter trials [8]. Therefore, the present study aimed to investigate the effectiveness of 4D-CTA in the diagnosis of arterial ED using 320-detector row dynamic volume CT. Our findings revealed that 4D-CTA using 320-detector row dynamic volume CT was a very promising and efficient option for accurately diagnosing arterial ED.

In the present study, CDDU results showed that in the EHS 1/2 group (n=35), PSV was 30.97 ± 5.16, EDV 7.94 ± 1.57, and RI 0.95 ± 0.07; in the EHS 3/4 group (n=38), PSV was 22.81 ± 2.79, EDV 3.28 ± 1.02, and RI 0.72 ± 0.05. CDDU, a minimally invasive and accurate method after ICI, is commonly performed in patients with urethral structure and can also determine the relationship between ED and trauma, which is considered as the gold-standard technique for evaluating penile hemodynamics [23]. Therefore, CDDU has been of great significance in classifying the cause and designing the course of treatment for ED, and therefore it is commonly performed in ED patients [24]. During CDDU, the PSV, EDV, and RI were measured. A flow rate of 30 cm/s or higher PSV represented normal arterial flow while a rate of 25 cm/s or lower PSV was considered to be arterial insufficient hence causing ED, and together with a normal arterial response, EDV > 6 cm/s and RI < 0.6 were considered to be normal [8]. In consistency with our findings, Pezeshki Rad et al. [25] demonstrated that both sensitivity and specificity of CDDU in diagnosing traumatic limb vascular injury was much higher, proving that CDDU is a promising tool in screening and diagnosis. Additionally, all patients in the EHS 1/2 group had a single-peak spectrum in systole with no or a rather low spectrum of blood flow in diastole, while patients in the EHS 3/4 group all had an increased blood flow spectrum in both systole and diastole after erection. Furthermore, in comparison with the EHS 1/2 group the proportion of patients with history of hypertension, hyperlipidemia, diabetes, and masturbation in the EHS 3/4 group was relatively low. Previous studies have also provided significant evidence on proving that any history related to testosterone deficiency, hypertension, hyperlipidemia, diabetes, and masturbation was indicative risk factors in ED [26,27].

Most importantly, we found that 4D-CTA was capable of displaying the cavernous artery, internal carotid artery, and penile dorsal artery simultaneously and, was capable of revealing the lesion sites clearly. With comparatively high diagnostic and angiogram accuracy, 4D-CTA using 320-detector row CT would appear as a very practical and useful method in diagnosing arterial diseases [12]. After angiography, a multislice CTA inspection clearly depicted draining veins, tumor feeding arteries, venous sinuses, and even fine branches and vessels near the skull [28]. According to 4D-CTA differentiating arteriovenous fistula subtypes, Beijer et al. [29] suggested that angiography should be considered as the gold standard for acquiring highly detailed image of arterial diseases and 4D-CTA was an additional first-line method for examining patients with arterial diseases. The use of 4D-CTA to diagnose ED yielded AUC of 0.879, with specificity of 93.9%, sensitivity of 82.5%, demonstrated that the accuracy of 4D-CTA diagnosing arterial ED was as accurate as CDDU. 4D-CTA was able to show each stage of contrast passage clearly and the after processing of 4D-CTA was very straightforward by automatic software like MIStar [13]. In addition, with the establishment of a low-dose radiation protocol, 320-detector row dynamic volume CT achieved a relatively low radiation dose at 5.08–5.87 mSv, which ensured a justified level of radiation exposure [30]. Under 320-detector row dynamic volume CT, the entire heart could be covered within one heartbeat [11].

To conclude, the present study demonstrated that 4D-CTA using 320-detector row dynamic volume CT is an extremely promising tool in diagnosing of arterial ED. As the study was conducted with a limited number of patients and a relatively low number of studies concerning 4D-CTA using 320-detector row dynamic volume CT in diagnosing arterial ED, its potential diagnostic accuracy still needs further experimentation and confirmation.

Funding

The authors declare that there are no sources of funding to be acknowledged.

Competing Interests

The authors declare that there are no competing interests associated with the manuscript.

Author Contribution

C.-C.X. and Y.-F.T. designed the study. G.-Y.W. and Q.-L.H. collated the data, designed and developed the database, conducted data analyses, and produced the initial draft of the manuscript. X.-Z.R. and J.-H.P. contributed to drafting the manuscript. All authors have read and approved the final submitted manuscript.

Acknowledgments

We would like to acknowledge the reviewers for their helpful comments on this paper.

Abbreviations: 4D-CTA, four-dimensional CT angiography; AVSS, audiovisual sexual stimulation; CDDU, color duplex Doppler ultrasound; DSA, digital subtraction angiography; ED, erectile dysfunction; EDV, end diastolic velocity; EHS, erection hardness score; ICI, intracavernous injection; MIP, maximum intensity projection; MPR, multiple planar reformation; NPT, nocturnal penile tumescence; PSV, peak systolic velocity; RI, resistant index; ROC, receiver operating characteristic; SAS, Self-rating Anxiety Scale; SDS, Self-rating Depression Scale; VR, volume rendering

References



 
 
ORIGINAL ARTICLE
Year : 2015  |  Volume : 9  |  Issue : 1  |  Page : 51-56 

Is unilateral transversus abdominis plane block an analgesic alternative for ureteric shock wave lithotripsy?

Ali Mohamed Ali Elnabtity1, Mohamed M Tawfeek1, Amr Ali Keera2, Yasser Ali Badran3
1 Department of Anesthesia and Intensive Care, Faculty of Medicine, Zagazig University, Zagazig, Egypt
2 Department of Anesthesia and Intensive Care, Faculty of Medicine, Benha University, Benha, Egypt
3 Department of Urology, Faculty of Medicine, Al Azhar University, Cairo, Egypt

Date of Web Publication11-Feb-2015

Correspondence Address:
Ali Mohamed Ali Elnabtity
Dr. Soliman Fakeeh Hospital, Palesteen Street, P.O. Box: 2537, Jeddah 21461, KSA

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0259-1162.150177

   Abstract 

Background: Various sedative and analgesic techniques have been used during shock wave lithotripsy (SWL).
Aim: This study aimed at evaluating the efficacy of ultrasound-guided unilateral transversus abdominis plane (TAP) block as an analgesic technique alternative during ureteric SWL.
Settings and Design: Prospective randomized comparative study .
Materials and Methods:
Fifty patients scheduled for ureteric SWL were randomly allocated into two equal groups: Group (F) received 1.5 mcg/kg fentanyl intravenous and group (T) received unilateral TAP block with injection of 25 ml of bupivacaine 0.25% (62.5 mg).
StatisticalAnalysis: Statistical analysis was performed using SPSS program version 19 and EP16 program.
Results: The visual analog scale was significantly less in group (T) than in group (F) both intra-operatively (at 10, 20, 30, and 40 min) and postoperatively (at 10 min intervals in the postanesthesia care unit [PACU]) (P < 0.001). Rescue analgesia with pethidine during the procedure and in the PACU was less (P < 0.001) in the group (T) than group (F) with a median of 20 mg versus 55 mg, respectively. The higher sedation scores observed in group (F) at 15, 25, and 35 min during the procedure, and at 20 min during the PACU time were statistically highly significant (P < 0.001), but only significant at 10 min (P = 0.03) and 30 min (P = 0.007) during the PACU time. There was also highly significant decrease (P < 0.001) in the time of PACU stay in group (T) (38.2 ± 6.6 min) compared with group (F) (89.2 ± 13.39 min). We recorded 6 patients in group (F) (24%) who have developed respiratory depression (respiratory rate < 10 breaths/min) compared to 0% in group (T) (P = 0.022). In addition, in group (F) nausea was noted in 8 patients (32%) and vomiting in 6 patients (24%), which was statistically significant when compared to group (T) (0%) (P = 0.01 and 0.022, respectively).
Conclusion: Ultrasound-guided unilateral TAP block is an effective alternative analgesic technique during ureteric SWL.

Keywords: Extracorporeal shock wave lithotripsy, local anesthetic, transversus abdominis plane block


How to cite this article:
Elnabtity AA, Tawfeek MM, Keera AA, Badran YA. Is unilateral transversus abdominis plane block an analgesic alternative for ureteric shock wave lithotripsy?. Anesth Essays Res 2015;9:51-6

How to cite this URL:
Elnabtity AA, Tawfeek MM, Keera AA, Badran YA. Is unilateral transversus abdominis plane block an analgesic alternative for ureteric shock wave lithotripsy?. Anesth Essays Res [serial online] 2015 [cited 2018 Mar 11];9:51-6. Available from: http://www.aeronline.org/text.asp?2015/9/1/51/150177


   Introduction 


Extracorporeal shock wave lithotripsy (ESWL) was introduced into clinical practice in 1980 as a first-line therapy for the majority of urinary stones. [1] Pain experienced during ESWL is still poorly understood but is believed to be multifactorial. The superficial skin nociceptors and visceral nociceptors such as periosteal, pleural, peritoneal and/or musculoskeletal pain receptors are responsible for pain during ESWL. [2] Other contributing factors include individual variations, the site and size of stones and pressure of shock waves produced by different types of lithotripters. [3]

Different analgesic agents, including opioids [4],[5] and local anesthetic agents, [6] as well as different analgesic techniques, such as general anesthesia, regional anesthesia, patient-controlled analgesia, and monitored anesthesia care have all been used to manage the pain during ESWL. [7] Fentanyl, a potent synthetic opioid, is commonly used during ESWL. The combination of fentanyl and other drugs like propofol has been proven as an effective intravenous (IV) analgesic technique but has significant side effects like respiratory depression, nausea, vomiting, and drowsiness. [8]

The ideal analgesic technique, offering pain-free treatment, free of adverse events, and cost-effective, remains to be established. [7] It has been proven in various literature that transversus abdominis plane (TAP) block provides good postoperative analgesia, when used in patients requiring abdominal wall incisions for total abdominal hysterectomy, lower segment caesarean section, prostatectomy, appendectomy, and laparoscopic surgeries. [9],[10],[11],[12] Using ultrasound improves the success rate and accuracy of TAP block and prevents its complications. [13] Previous studies on cadavers and volunteers have elucidated the ability of the TAP block to produce block of the lower six thoracic and upper lumbar sensory afferents. [14],[15]

The aim of our study was to evaluate the analgesic efficacy and safety of ultrasound-guided unilateral TAP block compared to IV fentanyl during ureteric SWL.


   Materials and methods 


After approval of the hospital's "Clinical Research Ethics Committee," a written informed consent was obtained from all patients enrolled in the study. This prospective randomized comparative study was performed over 11 months (from October 2013 to August 2014) at the Department of Urology in Dr. Soliman Fakeeh Hospital, Jeddah, Saudi Arabia. Fifty patients of American Society of Anesthesiologists (ASA) physical status I and II, aged 18-65 years old, of both gender, with single radiopaque ureteric stone scheduled for elective SWL, were included in this study. Exclusion criteria were patient's refusal, body mass index (BMI) <20 kg/m 2 or more than 30 kg/m 2 , coagulopathy and significant systemic or metabolic diseases. Patients with a history of substance abuse, psychiatric problems or allergy to any of the medications to be used in the study were also excluded.

On arrival to the lithotripsy unit, routine preoperative evaluation was performed, and the procedure was explained to all patients. Before premedication, each patient was instructed on the use of a standard 10 cm visual analogue scale (VAS) with "0" as no pain and "10" as the worst pain imaginable. Patients were advised not to move during the procedure and to ask for analgesia for intolerable pain or discomfort. Baseline measurements of heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), and room air oxygen saturation (SaO 2 ) were obtained using an electrocardiogram, a "Dinamap" automated blood pressure monitor, and a pulse oximeter, respectively.

After insertion of an IV cannula, paracetamol 1 g (Perfalgan , Bristol-Myer's Squibb) was infused to cover the pain of visceral origin. Afterward, Ringer's lactate infusion (10 ml/kg/h) was started, oxygen mask (6 L/min) was applied and IV midazolam (0.05 mg/kg) was given as a premedication.

Patients were randomly divided into two groups: Group (F) (n = 25) received fentanyl 1.5 mcg/kg IV immediately prior to the procedure, and group (T) (n = 25) received unilateral TAP block (described later). Intra- and post-operative data were recorded by a physician blinded to the study groups.

In group (T), the unilateral TAP block was performed in a supine position 10 min prior to the procedure. Using portable ultrasound device (SonoSite , Bothell, WA, USA), a linear 6-13 MHz ultrasound transducer was placed at the level of the anterior axillary line between the 12 th rib and the iliac crest of the same side of the ureteric stone. The puncture area and the ultrasound probe were prepared in a sterile manner. Using the in-plane technique with a skin entry at 1-2 cm away from the transducer, the skin was infiltrated with 1 ml lidocaine 1% and an 18-gauge Tuohy needle was advanced into the plane between the internal oblique muscle and the transversus abdominis muscle (TAM). Once the needle tip position was confirmed by injecting 2 ml of normal saline 0.9% and observing a hypoechoic pocket between the two muscles, 25 ml of bupivacaine 0.25% (62.5 mg) was injected slowly after negative aspiration. The drug was seen spreading in the TAP in a hypoechoic dark oval shape. Decreased sensation in the appropriate dermatomal levels of the same side of the procedure was confirmed by pinprick.

Shockwave lithotripsy was performed by SWL machine (Lithoskop ; combined X-ray/shock wave C-arm system, Siemens, Germany). The shock wave emitter was applied on the abdomen of the patients at the same side of the stone. Hemodynamic (HR and MAP) and respiratory (RR and SaO 2 ) variables and VAS scores were recorded at 5 min intervals intra-operatively and 10 min intervals in the postanesthesia care unit (PACU).

Patients who developed pain intra-operatively or in the PACU and with a VAS of more than (3) received 0.25 mg/kg IV pethidine, to be repeated on demand. The total amount of pethidine given to patients as rescue analgesia was recorded.

Sedation was assessed at 5 min intervals during the procedure and at 10-min intervals in the PACU using the Ramsay sedation score as follows:

  • 1 = Anxious or agitated,
  • 2 = Co-operative, oriented, and tranquil,
  • 3 = Responds to commands only,
  • 4 = Brisk response to a light glabellar tap or to a verbal stimulus,
  • 5 = Sluggish response to a light glabellar tap or to a verbal stimulus,
  • 6 = No response to stimulus. [16]


The incidence of nausea and/or vomiting from the onset of the procedure until discharge from the PACU was recorded. Ondansetron 4 mg IV was given as a rescue antiemetic. All patients were closely observed for symptoms and signs of local anesthetic toxicity (e.g. light-headedness, circumoral numbness, tongue paresthesia, arrhythmia, muscle twitches and convulsions) as well as the side effects of opioids, such as bradycardia (HR < 50 beats/min), hypotension (MAP < 20% of baseline), bradypnea (RR < 10 breaths/min), hypoxia (SaO 2 < 93%), and pruritus.

After completion of the procedure, the total number of shockwaves, their power and the total duration of the procedure were also recorded and considered for statistical analysis. Afterward, patients were transferred to the PACU. Criteria for discharge from the PACU include full consciousness, hemodynamic stability, ability to walk to the bathroom and void and absence of significant pain, nausea and/or vomiting. The length of PACU stay was recorded.

Sample size was calculated according to the following data: Confidence interval 95%, power of test 80%, ratio of unexposed to exposed 1:1, risk of decreased RR in fentanyl group 35% compared to 1% in TAP block group. Hence, the sample size was 50 patients, 25 in each group.

Statistical analysis was performed using  SPSS program version 19 (Armonk, NY: IBM Corp.) and EP16 program. Demographic data and side of the stones were analyzed using Student's t-test for numerical data and Chi-square test for categorical data. Perioperative variables and VAS during the procedure and in the time of PACU were analyzed using Student's t-test or Mann-Whitney U-test as appropriate. Sedation scores during the procedure and in the PACU time and the perioperative side effects were analyzed using Fisher's exact test and Chi-square test as appropriate. Data are presented as mean ± standard deviation, median, numbers, and frequencies as appropriate. P < 0.05 was considered statistically significant and < 0.001 was highly significant.


   Results 


From 56 consecutive patients scheduled for ureteric SWL during the study period, 6 patients were excluded. Three patients were excluded from group (F); two were shifted to general anesthesia due to patients' irritability and one had required ureteric stent insertion. Three patients were also excluded from group (T); TAP block failed completely in one patient, and the other two patients underwent ureteroscopic lithotripsy due to stone impaction. Finally, 50 patients were enrolled in the study, 25 in each group and were considered for analysis [Figure 1].

Demographic data of the patients (sex, age, weight, height, BMI, and ASA classification), and side of the stones were comparable and no statistically significant differences were observed between the two groups [Table 1].

There were also no significant differences between the two groups regarding duration of SWL, number of shock waves, and the maximum power of shock waves needed to crush the stones [Table 2].

Rescue analgesia in the form of pethidine 0.25 mg/kg was administered in both groups. Statistical analysis showed highly significant decrease (P < 0.001) in the total amount of pethidine used during the procedure and in the PACU time in group (T) (median = 20 mg) compared to group (F) (median = 55 mg) [Table 2].

There was a highly significant decrease (P < 0.001) in the time of PACU stay in group (T) (38.2 ± 6.6 min) compared to group (F) (89.2 ± 13.39 min) [Table 2].

Visual analog scale scores showed a highly significant decrease in group (T) than group (F) at 10, 20, 30, and 40 min during the procedure [Figure 2], and at 10 min intervals in the PACU (P < 0.001) [Figure 3].
Figure 2: Visual analog scale values during shock wave lithotripsy. Data are presented as mean ± standard deviation. *P<0.001 = Highly significant compared to group (T)

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Figure 3: Visual analog scale values during postanesthesia care unit time. Data are presented as mean ± standard deviation. *P<0.001 = Highly significant compared to group (T)

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Sedation scores showed highly significant increase in group (F) compared to group (T) at 15, 25, and 35 min during the procedure [Table 3] and at 20 min during the PACU time (P < 0.001) [Table 4], while there was a significant increase in sedation scores in group (F) than those in group (T) at 10 min (P = 0.03) and 30 min (P = 0.007) during the PACU time [Table 4].

There were no reported cases of bradycardia (HR < 50 beats/min), hypotension (MAP < 20% of baseline), hypoxia (SaO 2 < 93%) or signs of local anesthetic toxicity in both groups [Table 5].

Six patients in group (F) (24%) developed respiratory depression (RR < 10 breaths/min) without hypoxia compared to 0% in group (T) (P = 0.022) [Table 5].

Although one patient in group (F) (4%) complained of mild pruritus, it was statistically insignificant when compared to group (T) (0%) [Table 5].

Eight patients have had nausea (32%) and 6 have had vomiting (24%) in group (F), which was statistically significant when compared to group (T) (0%) (P = 0.01 and 0.022, respectively) [Table 5].


   Discussion 


In the present study, we found that ultrasound-guided unilateral TAP block compared to IV fentanyl-was a very good analgesic technique for ureteric SWL as it provided a very good analgesia during the procedure with significantly lower doses of rescue analgesia, lower sedation scores and shorter times to discharge from the PACU without significant side effects.

The clinical efficacy of TAP block has been proven in many clinical trials of adults undergoing abdominal operations. It has also been used for postoperative analgesia following renal transplantation, reconstruction flaps of the anterior abdominal wall and inguinal lymphadenectomy. [9],[10],[11],[13],[17],[18] McDonnell's et al. injected iopamidol contrast, and then, using computerized tomography and magnetic resonance imaging, studied the spread of the contrast within the TAP into three volunteers. They found that the contrast spread from the superior margin of the iliac crest up to the costal margin and extended posteriorly till the quadratus lumborum muscle. [14] A cadaveric study was done by Tran et al. in which 20 ml of aniline blue dye was injected into the TAP in the mid-axillary line. They noticed spread of the dye between the iliac crest, the costal margin and the lateral border of the rectus abdominis sheet. [15]

Although TAP block has been always used as a part of multimodal analgesia in combination with other drugs, [10] we used it in our study as the sole analgesic technique during ureteric SWL in which the shock wave emitter was applied to the ipsilateral anterior abdominal wall. The newer versions of SWL machines have reduced the amount of analgesia and sedation required during the procedure because of their lower shock wave output energy which is less painful than it used to be. [19] Rickford et al. presented a prospective randomized study to evaluate the use of general, epidural, and spinal anesthesia during ESWL. They found that general anesthesia has the advantages of being rapid and reliable, but resulted in postoperative nausea, vomiting, and sore throat. Epidural anesthesia consumed more time than spinal anesthesia and more supplementary drugs like fentanyl and midazolam. Spinal anesthesia showed a high incidence of postspinal headache. But both epidural and spinal anesthesia conferred awake and cooperative patients. [20]

In our study, we found that ultrasound-guided TAP block was an easy, rapid, and reliable analgesic technique with no significant side effects. Patients were awake and cooperative during the procedure, and they were early ambulated and discharged from the PACU. Ali and El Ghoneimy presented a comparative study between dexmedetomidine and fentanyl as adjuvant to propofol in children undergoing ESWL. They found that the RR values in the propofol/fentanyl group were significantly lower than the baseline throughout the procedure compared to the propofol/dexmedetomidine group and were significantly lower than the propofol/dexmedetomidine group at all-time intervals during the procedure. [21] These results are similar to the results obtained in our study. There was a significant decrease in the RR values in the fentanyl group (although without hypoxia) and was managed conservatively. In addition, nausea and vomiting was significant in the fentanyl group in comparison to the TAP block group; yet all patients responded to IV ondansetron 4 mg.

Regarding sedation scores, there was a highly significant increase in the mean values in group (F) compared to group (T) at 15, 25, and 35 min during SWL and at 20 min during the PACU time.

The strong analgesic effect of ultrasound-guided TAP block is due to block of the lower six thoracic and upper lumbar sensory afferents, [14],[15] where the anterior rami of the lower six thoracic nerves and the first lumbar nerve provide sensory supply to the skin, muscles and parietal peritoneum of the anterior abdominal wall. The ilio-hypogastric, ilio-inguinal, intercostal, and subcostal nerves pass through the plane between the internal oblique and TAMs to provide sensory supply to the abdominal wall. [14],[18] To our knowledge, this is the first study which evaluated the efficacy and safety of ultrasound-guided unilateral TAP block for ureteric SWL.

Limitations to the technique described in our study (i.e. ultrasound-guided TAP block) include being restricted to ureteric stones in which the shock wave emitter would be applied to the ipsilateral anterior abdominal wall and not renal stones where the emitter would be applied posterior to the mid-axillary line. Second, our study was extended only till the end of PACU time. Further studies on a larger number of patients are required for long-term follow-up.


   Conclusion 


Ultrasound-guided unilateral TAP block is an effective alternative analgesic technique for ureteric SWL as it provides an optimal analgesic condition, less rescue analgesia, less intra-and postprocedural sedation, early ambulation, and early discharge from PACU with no significant side effects.

 
   References 

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    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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