| BackgroundPenis diseases such as phimosis,hypospadias and concealed penis are common and required for corrections in pediatric surgeries.The caudal block with general anesthesia is commonly used in pediatric penis surgeries.The caudal block a well-established,easy to operate through performers’handle with a definite effect technique.However,there are still several disadvantages of the caudal block:1)in the children with obese,nerve location is difficult due to difficultly identifying the surface anatomical signs;2)high anatomical variation of the fistula;some boy have anatomical abnormalities,deformities or atresia of the fistula;3)adverse effects such as hematoma and local anesthetic mis-invasion of blood vessels;4)children with the caudal block are prone to the numbness of lower limbs,the hypotension and the urinary retention,reducing the hospitalization comfort,and leading to postoperative anxiety,irritability and prolonged hospital stay;5)recent studies suggest that caudal block may increase the incidence of postoperative urethral fistula in children undergoing hypospadias repair.Therefore,it is necessary to advance the traditional caudal block by developing a novel nerve block which can easily locate and more precisely block peripheral nerves with high specificity to control the penis pain.The new nerve block can produce exact analgesia without the abovementioned side effects of the caudal block,and finally improve the quality of medical services for children undergoing penile surgeries.Anatomically,pains of the penis are controlled by the dorsal penile nerve.The dorsal penile nerve is arises from the sacral plexus,and is the terminal branch of the pudendal nerve.It follows the ischial,pubic symphysis,the anterior border of the decidua of the genitourinary tract,the back of the penis,and finally innervates the skin of the penis and glans.Thus,we hypothesized that the use of dorsal penile nerve block in the place of the caudal block could provide precise analgesia for children undergoing penile surgeries,avoiding side effects of the caudal block.The dorsal penile nerve can be blocked by a traditional approach.Detailed procedures include:inserting the needle to the dorsal side of the base of the penis and reaching the pubic symphysis,then injecting local anesthetics to achieve nerve block effects through the infiltration and the spread of the injected anesthetic drug.The success of this method mainly depends on identifying accurately anatomical surface marks and providers’ experiences.Also,this traditional method has some disadvantages such as a high failure rate and incomplete analgesia.Additionally,the ultrasound-guided dorsal penile nerve block is also an acceptable approach for blocking the dorsal penile nerve.However,in performing the dorsal penile nerve block under an ultrasound,neurovascular ultrasound images cannot be observed,the infiltration of local anesthetics into target peripheral nerves cannot be detectived.By analyzing the perineal vascular deformations,we find that the penile artery in the superficial perineal space is always accompanied by the penile vein and branches as well as the dorsal penile nerve and that these structures finally form a neurovascular sheath at the dorsal part of the penis.Thus,it can be hypothesized that the dorsal penile nerve block could be achieved by injecting local anesthetics into the neurovascular sheath assissted by identifying pulsations of arteriae penis guided by an ultrasound probe.Wherefore,we conducted the following studies to convince the effectiveness of the hypothesized method.First of all,through an anatomical study of the dorsal penile nerve and the pudendal nerve,we clarified the structure and distribution of the pudendal nerve and the dorsal penile nerve in the perineum in normal male human bodies.Secondly,common types of pediatric penile surguries such as circumcision and hypospadias repair were adopted to evaluate the safety and efficacy of the ultrasound-guided dorsal penile nerve block via perineal approach.Finally,we evaluated the safety of dexmedetomidine,a commonly used local anesthetic adjuvant,and whether it could prolong the analgesic time of this peripheral nerve block.Study Ⅰ:An anatomical study of the dorsal penile nerve and the pudendal nerve.1.ObjectiveTo study the structure and distribution of the pudendal nerve and the dorsal penile nerve in the perineum in normal male human bodies and to provide anatomical theoretical basis for the development and applications of the dorsal penile nerve block in pediatric penile surgeries.2.Materials and methodsTwelve formalin-fixed adult male cadaver specimens with unimpaired pudendum at unknown ages were used in the study.Dissect the free pudendal nerve,its branches,and accompanying blood vessels.Observe the distribution and accompanying blood vessels of the dorsal penile nerve and measure the outer diameter of the original part of each dorsal nerve.Dissect the free ischiocavernosus muscle and bulbospongiosus muscle;observe their structure and the spatial relationship of the dorsal penile nerve.3.ResultsThe pudendal nerve and its three major branches(the anal nerve,the perineal nerve,and the penile dorsal nerve)were successfully dissected of all the 12 specimens.The outer diameter of the left dorsal penile nerve is 1.41±0.10 mm and that of the right dorsal penile nerve is 1.37± 0.10 mm.The penile artery,the penile vein and the dorsal penile nerve form a neurovascular sheath and travel in the dorsal penis.Bilateral dorsal penile nerve and their accompanying vessels travel through the space between the bulbospongiosus muscle and the ischiocavemosus muscle.4.ConclusionsThe dorsal penile nerve is the terminal branch of the pudendal nerve.It has a relative small diameter and travels in the dorsal penile neurovascular sheath in the spatia perinei superficiale.The dorsal penile nerve can be located through the bulbospongiosus muscle,the ischiocavernosus muscle and the penile artery.Study Ⅱ:A study investigating the safety and the efficacy of theultrasound-guided dorsal penile nerve block via perineal approach in pediatric circumcision.1.ObjectiveTo evaluate the safety and the efficacy of the ultrasound-guided dorsal penile nerve block via perineal approach in pediatric circumcisionin comparison to the caudal block;to provide a reference for improve anesthesia methods in pediatric circumcision.2.Materials and methodsOne hundred and four scheduled for circumcision pediatric patients,aged 7 years to 14 years with ASA I were selected and divided randomLy into 2 groups(n=52):the caudal block group(Group CB)and the dorsal penile nerve block(Group DPNB).General anesthesia induced and maintenanced with inhaled sevoflurane,and inserted a laryngeal mask with spontaneous breathing.The ultrasound-guided dorsal penile nerve block via perineal approach was performed through injecting 0.25%of ropivacaine at 0.15mL/kg/side,total 0.3mL/kg injection for both sides in the Group DPNB.The same concentration of ropivacaine was given by the caudal canal at a dose of 0.5 mL/kg in the Group CB.Heart and respiratory rates of five time-points(T1,immediately before induction;T2,immediately after insertion of the laryngeal mask;T3,immediately after circumcision;T4,immediately after final suture;T5,immediately after removal of the laryngeal mask),pain level when leaving the PACU,the time of analgesic demand,and the first time taken micturition after surgery were recorded and analyze between the two groups.3.ResultsNingthy pediatric patients were good to incluced with fourteen dropped in this study:forty-three in the Group CB and forty-seven in the Group DPNB.There was no significant difference in heart and respiratory rates before and during the surgery,and the pain scores when pediatric patients leave the PACU were similar(P>0.05).However,the first time for micturition after circumcision in the Group CB is longer than the Group DPNB(P<0.01).The boys in the Group CB asked for analgesics earlier than in the Group DPNB(P<0.01).Six boys in the Group CB suffered numbness of the lower limbs.No other adverse effects were found in the two groups.4.ConclusionsThe ultrasound-guided dorsal penile nerve block via perineal approach shows the safety and the efficacy in pediatric circumcision surgeries.By compared with caudal block,ultrasound-guided perineal approach dorsal penile nerve block can achieved satisfactory anesthetic effect by less dosage of local anesthesia,prolong the duration of analgesia,and avoid/reduce the complications of caudal block.Study Ⅲ:A study on the safety and efficacy of dorsal penile nerve block via perineal approach under ultrasound-guided in children with hypospadias repair surgeries.1.ObjectiveTo evaluate the safety and efficacy of the ultrasound-guided dorsal penile nerve block in children with hypospadias repair(anterior urethroplasty)surgeries.2.Materials and methodsThirty-four pediatric patients scheduled for hypospadias repair surgeries,aged 1 years to 14 years with ASA Ⅰ were selected and divided randomLy into 2 groups(n=17):the caudal block group(the Group CB)and the dorsalpenile nerve block(the Group DPNB).The anesthesia method is the same as described in the Study Ⅱ.Heart and respiratory rates of five time-points before and during the surgery(T1,immediately before induction;T2,immediately after insertion of the laryngeal mask;T3,immediately after skin incision;T4,immediately after final suture;T5,immediately after removal of the laryngeal mask),pain level when leaving the PACU,the time of analgesic demand after surgery were recorded and analyzed between the two groups.The length of hospital stay and the incidence of urethrocutaneous fistula were also compared between the two groups.3.ResultsTwenty-eight pediatric patients were included with six dropped in this study:thirteen in the Group CB and fifteen in the Group DPNB.There was no significant difference in heart rates(except T4 time-point)and respiratory rates before and during the surgery,and the pain scores when pediatric patients leave the PACU were not significantly different(P>0.05).However,the boys in the Group CB asked for analgesics earlier than in the Group DPNB(P<0.05).Three boys in the Group CB suffered the numbness of the lower limbs.No critical difference at the length of hospital stay and the incidence of urethrocutaneous fistula were found in both groups(P>0.05).4.ConclusionsThe ultrasound-guided dorsal penile nerve block via perineal approach is safe and effective in pediatric hypospadias repairsurgeries(anterior urethroplasty).The DPNB is an appropriate alternative to the caudal block in pediatric hypospadias repair(anterior urethroplasty)surgeries.Study IV:A study on testifying the safety and efficacy of dexmedetomidine combining with ropivacaine in the ultrasound-guided dorsal penile nerve block via perineal approach in pediatric circumcision.1.ObjectiveTo evaluate the efficacy and safety of dexmedetomidine combining with ropivacaine in the ultrasound-guided dorsal penile nerve block via perineal approach in pediatric circumcision.2.Materials and methodsForty boys scheduled for the circumcision,aged 7 years to 14 years,with ASA I were selected and divided randomLy into two groups(n=20):twenty in each group:the control group(Group Co)and the dexmedetomidine group(Group Dex).General anesthesia induced and maintenanced with inhaled sevoflurane,and inserted a laryngeal mask with spontaneous breathing.The dorsal penile nerve block via perineal approach under ultrasound-guided was performed all two groups.The Group Co received a mixed solution made up of 0.25%of ropivacaine at total 0.3mL/kg plus 1 mL saline solution for both sides.The Group Dex received a mixed solution made up of 0.25%of ropivacaine at total 0.3mL/kg plus 1 mL 0.5μg/kg dexmeditomidine for both sides.Heart and respiratory rates of five time-points(T1,immediately before induction;T2,immediately after insertion of the laryngeal mask;T3,immediately after circumcision;T4,immediately after final suture;T5,immediately after removal of the Laryngeal Mask),pain level when leaving the PACU,recovery time after anesthesia,agitation scores and the time of analgesic demand after surgery were recorded and analyzed between the four groups.3.ResultsThirty-seven pediatric patients were included with three dropped in this study:eighteen in the Group Co,nineteen in the Group Dex.There was no significant difference at respiratory rates before and during the surgery,and the pain scores when pediatric patients leave the PACU were similar(P>0.05).The heart rate of Group Dex was significantly lower than that of Group Co at T3-T5(P<0.05),but not lower than 70 beats/minute.Recovery time after anesthesia and agitation scores in PACU were not significantly different(P>0.05).However,the patients in the Group Co asked for analgesics earlier than those in the Group Dex(P<0.01).No other obvious adverse effects were observed in the two groups.4.ConclusionsAs an adjuvant,dexmedetomidine(at a dose of 0.5μg/kg)combining with ropivacaine is safe in the ultrasound-guided dorsal penile nerve block via perineal approach,and can prolong the effective analgesia after surgeries. |
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