Operative Site Research Articles

Deep brain stimulation for Parkinson's disease: experience, benefits and limitations in a center in Latin America

Parkinson's disease is poorly studied in Colombia. It is pharmacologically managed, but for refractory cases, surgery is a therapeutic option, positively impacting on quality of life. To determine the impact of deep brain stimulation as management in the control of progression in patients with Parkinson's disease attended our institution between the years 2014 to 2020. Descriptive retrospective study, with patients collected between 2014 and 2020 undergoing deep brain stimulation surgery. The MDS-UPDRS (Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale) was applied in the pre- and postoperative period, and the results were compared. 21 patients were included and the UPDRS was applied, finding a decrease in scores in the postoperative period. One patient had an operative site infection. There was an improvement in the MDS-UPDRS score, with a low rate of complications. The procedure time was prolonged from the preoperative evaluation. Deep brain stimulation is the management of choice for refractory Parkinson's disease. The patients in this series showed improvement in their symptoms. Unfortunately, there are limitations to perform this procedure in Colombia, such as the delay in the authorization of the procedure.

Prospects for the creation and development of radio electronic devices diagnostic systems with built-in software.

In the article, the issues of the current state of military-political relations of Ukraine (stable direction towards integration with NATO standards and real combat operations in the east of the country) are connected with the creation of an effective system of monitoring the technical condition of weapons and military equipment (foreign manufacturers of different countries and years of manufacture) in places of their direct application. Changes in military and political relations that are taking place in the world lead to changes both at the global level and in the middle of Ukraine. The level of the enemy's equipment with modern weapons, as well as the rapid development of scientific and technical progress, prompts a review of views on the forms and methods of conducting hostilities, the form of logistical support, the state and organization of an effective system of technical support and repair of military equipment and weapons. By an effective system for monitoring the technical condition (diagnosis) of radio-electronic weapons, we mean a set of hardware and software tools (based on computer-measurement systems) that are designed to solve the problems of technical diagnosis and ensure an increase in the reliability and efficiency of the weapon with an optimal cost-effectiveness ratio on the system - the effect of application. At the moment, with the increasing complexity of modern radio-electronic weapons, the increase in the number of controlled parameters, the miniaturization of the size of elements, as well as the low level of equipment with systems that perform the functions of forecasting and diagnosis, the tasks of predicting failures, reducing recovery time, saving resources of forces and means are urgent necessary for solving diagnostic problems, especially at the sites of operation of radio-electronic weapons.

Photoimmunotherapy of Prostate Cancer With Antibody and Fab Fragments Targeting the Prostate Specific Membrane Antigen.

The standard treatment for localized prostate cancer involves surgical removal of the prostate with curative intent. However, when tumor cells persist in the operation site, there is high risk of local recurrence and tumor spread, leading to stressful follow-up treatments, impaired quality of life, and reduced overall survival. This study examined photoimmunotherapy (PIT) as a new treatment option for prostate cancer cells. We generated conjugates consisting of either a humanized antibody or Fab fragments thereof targeting the prostate specific membrane antigen (PSMA), along with our silicon phthalocyanine photosensitizer dye WB692-CB1. PSMA-expressing prostate cancer cells were incubated with the antibody dye or Fab dye conjugates and cell binding was measured using flow cytometry. Cells were irradiated with varying doses of red light for dye activation, and cytotoxicity was determined by erythrosin B staining and subsequent analysis using a Neubauer counting chamber. Specific cytotoxicity was induced with the antibody dye conjugate in the prostate cancer cells in a light dose-dependent manner. Treatment of the cells with the Fab dye conjugate resulted in lower cytotoxicity, which could be attributed to a reduced binding affinity and a reduced dye uptake of the Fab fragment. Our new antibody dye and Fab dye conjugates offer potential for future intraoperative PIT in patients with localized prostate cancer, with the aim to ensure complete removal of tumor cells from the surgical area, to avoid local recurrence, and to improve clinical outcome.

Assessment of high-flow nasal cannula efficacy in humidification of infant airways: A computational fluid dynamics approach

IntroductionHigh-flow nasal cannula therapy has garnered significant interest for managing pathologies affecting infants' airways, particularly for humidifying areas inaccessible to local treatments. This therapy promotes mucosal healing during the postoperative period. However, further data are needed to optimize the use of these devices. In vivo measurement of pediatric airway humidification presents a challenge; thus, this study aimed to investigate the airflow dynamics and humidification effects of high-flow nasal cannulas on an infant's airway using computational fluid dynamics. MethodsTwo detailed models of an infant's upper airway were reconstructed from CT scans, with high-flow nasal cannula devices inserted at the nasal inlets. The airflow was analyzed, and wall humidification was modeled using a film-fluid approach. ResultsAir velocities and pressure were very high at the airway inlet but decreased rapidly towards the nasopharynx. Maximum relative humidity—close to 100%—was achieved in the nasopharynx. Fluid film development along the airway was heterogeneous, with condensation primarily occurring in the nasal vestibule and larynx. ConclusionThis study provides comprehensive models of airway humidification, which pave the way for future studies to assess the impact of surgical interventions on humidification and drug deposition directly at operative sites, such as the nasopharynx or larynx, in infants.

Efficacy Of Local Infiltration Of Bupivacaine In Controlling Post Operative Port Site Pain Vs Conventional Analgesics Following Laparoscopic Cholecystectomy

Efficacy Of Local Infiltration Of Bupivacaine In Controlling Post Operative Port Site Pain Vs Conventional Analgesics Following Laparoscopic Cholecystectomy

Research on Edge Cloud Data Storage Method of Power Operation Site in Internet of Things Environment Based on Paxos Algorithm

Abstract In order to realize the efficient storage of electric power job site data and ensure the utilization effect of the stored data, a method of electric power job site edge cloud data storage based on the Paxos algorithm is proposed. In this method, power field operation data are collected comprehensively through the edge server and edge controller in the edge computing module, the collected data are processed, and the data storage tasks are allocated reasonably. The allocated data are transferred to the data storage module, which identifies the bad data in the data through a gap statistics algorithm and cluster analysis and retains the valid and normal data. After the primary and secondary nodes are determined based on the Paxos algorithm, the data storage model of power operation site is constructed. After the consistency detection of the reserved data, the data storage of power operation site is completed. The platform management module can analyze the stored data and present the analysis results to the application decision-making module for presentation. The test results show that the maximum time delay and energy consumption are 2.15 s and 42.6 W, respectively, when the method is used for data transmission, which can accurately identify the bad data in the field data of electric power operation, and the reliability index results of data consistency detection are all above 0.95, which ensures the good consistency of the stored power operation site data and effectively completes the power operation site data storage.

Menstruating Skin: Utero-Cutaneous Fistula Coexisting with Scar Endometriosis: A Case Report

Abstract Scar endometriosis and utero-cutaneous fistula (UCF) complicating cesarean section is a rare occurrence, and only a few cases have been reported in the literature. The patient developed cyclical bleeding from the previous operation site associated with abdominal pain. The bleeding occurred whenever she was having her menstrual period. At presentation, an initial diagnosis of scar endometriosis was made. She had surgical excision of the fibrotic subcutaneous tissue and rectus sheath with the repair of the fistulous uterus. The result of the histopathological examination was scar endometriosis and UCF. She did well post-surgery and was discharged home, and the follow-up clinic visits were not eventful. Cesarean section wound infection is a risk factor for UCF formation and scar endometriosis. Meticulous excision of the endometriotic skin, the fistulous tract, and repair of the fistulous uterus is an effective management modality.

Pecial features of surgical approach for patients with Dupuytren's contracture (our experience)

Objective. Although many years history of study, the issue of treating patients with Dupuytren's contracture keeps on being relevant. It is due to high incidence of this pathological condition among the population (up to 8.2%), the lack of a unified surgical treatment approach, and a high risk of postoperative complications (up to 40%). Existing approaches to the treatment do not ensure the absence of condition recurrence and are related to a long recovery period (up to 12 months).Purpose of the study: to improve the outcomes and reduce the treatment period of the patients with Dupuytren's contracture by creating and integrating algorithm for choosing the optimal surgical intervention in clinical practice.Material and methods. The study involved two parts. In the first part data of surgical treatment performed for 8962 patients with Dupuytren's contracture (10213 surgeries) operated during the period of 2007–2022 were analyzed. 6632 male (74%) and 2330 female (26%) were enrolled in the study. The patients’ mean age was (57 ± 6) years old (from 24 to 92 years old). 9396 needle fasciotomies (92%), 562 subtotal fasciectomies (5.5%), and 255 inspection interventions for recurrence after subtotal fasciectomy (2.5%) were performed.In the second part of the study, we suggested a universal algorithm for choosing the optimal technique of surgical treatment of patients with Dupuytren's contracture, depending on the severity, the presence of concomitant skin problems in the operation site (tightening scars or trophic lesions), the number of recurrences, and the method having caused them.Results and discussion. The follow-up period ranged from 3 to 15 years. Treatment outcomes were assessed using the qDASH scale and the treatment satisfaction subjective scale. Perfect treatment outcomes were obtained in 56.8% of cases, good – in 28.2%, satisfactory – in 11.1%, and unsatisfactory – in 3.9% of cases. Complications (iatrogenic damage to the dactylar nerves and arteries, flexor tendons, ruptures and deep skin cracks, and superficial infectious complications) occurred in less than 8% of patients. Contracture recurrences were noted in 5370 cases (52.6%).The analysis of our own 15-year experience (more than 10000 surgeries) as well as the study of colleagues’ experience (according to the literature) allowed us to formulate the guidance for choosing the approach of treating the patients with various forms of Dupuytren's contracture.In primary Dupuytren's contracture, we recommend needle fasciotomy (or collagenase injections) as a quick, minimally invasive surgical procedure causing minimal complications and contraindications (less than 8%). In severe cases, rehabilitation under the monitoring of a hand physician is recommended after the surgery.If the recurrence takes place after needle fasciotomy, a repeated minimally invasive procedure may be conducted. The condition recurring three or more times, we recommend considering the open surgery – subtotal fasciectomy accompanying by obligatory epidermic grafting (not palmar skin): cross-finger flap, dorsal metacarpal artery bond flap (Quaba/Maruyama), or full-thickness free skin graft taken from the forearm.The recurrence after subtotal fasciectomy occuring, the presence of tightening scars and trophic lesions should be assessed. In some cases, the tightening scars lack, a needle fasciotomy may be conducted by specialists having mastered the technique. In other cases, trophic lesions absent, we consider the inspection subtotal fasciectomy accompanied by the obligatory closure of the soft tissue defect using a full-thickness skin autograft or bond flap (not palmar skin) must be performed.Obligatory patients’ follow-up for two years (medical examinations every six months) after the surgery to identify the early signs of recurrence, collagenase or steroids injections into the palmar aponeurosis nodes (and/or physiotherapy with Fermencol) in case of disease progression, or prophylactic radiotherapy immediately after the surgery virtually allow to eliminate the risk of the condition recurrence.Conclusions. Analysis of the treatment outcomes of patients with Dupuytren's contracture of varying severity allowed us to work out a universal algorithm for choosing the optimal tactics of surgical treatment of the condition enabling improving the outcomes, reducing the recovery period, and decreasing the risk of recurrence.

Modified Endaural Approach With a Peripheral Dissection of the Superficial Musculoaponeurotic System to Access the Temporomandibular Joint to Prevent Facial Nerve Injury.

The purpose of this study was to assess the effects of protecting the facial nerve with a modified endaural approach with a peripheral dissection of the superficial musculoaponeurotic system to access the temporomandibular joint which allows an excellent operative field of visualization, multiple surgical procedures of the temporomandibular joint, and general care which improves the immediate postoperative period, making this a less morbid surgery. This study included 33 patients (39 sides) who underwent surgical treatment for disorders of the temporomandibular joint from the years 2021 to 2023 at the maxillofacial department of the clinic "Colsanitas" located in Bogota, Colombia. Therapeutic results were evaluated by postoperative facial nerve injury, with the House-Brackman scale; every patient was examined for adequate facial musculature function immediately after surgery. Notably, zero patients presented facial nerve injury. These results imply that the modified endaural approach with a peripheral dissection of the superficial musculoaponeurotic system to access the temporomandibular joint reduces the incidence of facial nerve injuries, improves operative site exposure, and lowers the frequency of complications.

Syndactylized glabrous flaps for multiple finger palmar defects.

Palmar finger or pulp defects require coverage with glabrous tissue to achieve a good match with the lost tissue. The management of multiple finger palmar or pulp defects is challenging because these defects may not always be suitable for local or pedicled flaps. In such situations, syndactylizing free or pedicled flaps can be used. We evaluated the results of free glabrous flaps syndactylizing across multiple finger defects. The two flaps used were the superficial branch of the radial artery (SUPBRA) flap and hypothenar free flap. Seven syndactylized glabrous free flaps were used to cover the defects in 16 fingers. The functional results and complaints were also assessed. Mean flap size was 14.35 cm2. Six flaps survived. Postoperative evaluation data were obtained for the 13 fingers. All the patients returned to their previous work. All patients had a diminished protective sensation of at least 4.31 according to the SWM test. The mean two-point discrimination score of the patients was 9.9 mm (7-14). One finger had a PIP joint flexion contracture of 30°, no donor-site complaints were observed. The advantages of these flaps include single operation site, strong glabrous tissue coverage, low risk of flexion contracture, and adequate tissue size for large defects. Disadvantages include two-stage and complex microsurgical operations, prolonged treatment, and hospital stay.

Suture-Needle Management Device and Novel Port Configuration for Robotic Sacrocolpopexy.

Robot-assisted sacrocolpopexy (SCP) is a commonly performed procedure for the repair of apical pelvic organ prolapse; therefore, novel devices and techniques to improve safety and efficacy of this procedure should be explored. The objective of this study was to assess safety and efficacy of 8-mm trocar site for use of a disposable suture/needle management device (StitchKit; Origami Surgical, Madison, NJ) for robot-assisted SCP with a 4-arm configuration and no assistant port. This is a retrospective case series of patients undergoing robot-assisted SCP at a tertiary center from 2018 to 2021. All surgical procedures were performed using four 8-mm robotic trocars and StitchKit device. Our objective was to review all cases in which this technique was used to determine whether the approach resulted in a safely completed procedure and any complications or adverse events. Secondary objectives were to describe patient and operative characteristics. In total, 422 patients underwent robot-assisted SCP for pelvic organ prolapse. The mean age was 60 ± 10 years, and mean body mass index was 27 ± 6 (calculated as weight in kilograms divided by height in meters squared). Most patients had stage 3 prolapse (73%) and underwent concomitant hysterectomy (70%). Ninety-nine percent (n = 416) of cases were completed robotically. StitchKit was successfully inserted and removed in all robotic cases with correct needle counts. All patients had postoperative visits, and 80% followed up at 3 months. No umbilical/port site hernias, operative site infections, or adverse events were reported. Robot-assisted SCP can be performed safely using a 4-arm robotic configuration and suture kit device. This setup eliminates incisions greater than 8 mm and an assistant port, allowing for surgical efficiency without compromising patient outcomes.

Automated machine learning driven model for predicting platform supply vessel freight market

Platform Supply Vessels (PSVs) play an essential role in supporting oil and gas platforms, and other offshore structures by transporting crew members, personnel, provisions, and further indispensable equipment from onshore to operational sites. PSV freight rate movements are subject to a complex array of non-linear interconnected influential factors. Reviewed literature reveals an absence of forecasting studies predicting PSV freight rates. Meanwhile, Automated Machine Learning (AutoML) frameworks have never before been employed to forecast maritime freight rates. Therefore, this study investigates factors influencing PSV time charter freight rates and explores AutoML modelling in capturing non-linearities while forecasting PSV freight rates over a 1, 3 and 6-month out-of-sample forecast horizon. A total of 43 relevant factors are included in prediction modelling, the most comprehensive number of explanatory variables in the shipping forecasting literature to date. The data consists of 188 monthly observations collected from two databases: Clarksons Shipping Intelligence Network and Offshore Intelligence Network. Time-lagged variables are utilized as data of explanatory variables are not immediately available at the time of forecasting. A total of 79 complex machine learning models are tested, and the best-performing models are Eureqa Generalized Additive Model, eXtreme Gradient Boosted Trees Regressor, and Ridge Regressor with Forecast Distance Modelling, benchmarked against the proven statistical forecasting model triple exponential smoothing. The most influential factors are historical PSV time charter freight rates, newbuilding prices, number of vessel deliveries, orderbook number, total vessel sales, and the unique variable number of active drilling rigs in the market.

Ensuring uniformity of measurements in the European Metrology Cloud

The main requirements for the calibration of measuring channels of distributed measuring instruments at the operation site are described. When preparing for calibration, the use of portable discharge working measurement standards, which consist of a reference voltage source and a divider, is substantiated. The proposed structure of the device for calibration is based on a divider of single-nominal resistors and corresponding algorithms for processing the conversion results. The feasibility of using a divider in which the resistors are closed in a ring is substantiated. To ensure the invariance to residual parameters of switching elements when implementing several evenly spaced calibration points in the conversion range, a potential-current switching of both the input reference voltage and the output converted voltage is proposed. In addition, a method to correct the equivalent additive error component of the entire measuring channel during its calibration is proposed. The expediency of the studied measuring channels to obtain intermediate conversion results is shown. An algorithm and method of processing intermediate conversion results to obtain code values at all calibration points are proposed. To process these results, it is advisable to apply an additional software in the European Metrology Cloud. It is shown that the calibration error of the measuring channels at the operation site is determined by the error of the reference voltage source.

Determination of air emission factor of pollutants from local crude oil refineries

High emission factor of identified air pollutants from the artisanal petroleum refineries in the Niger Delta region may be key to the degrading air quality of the region. This study determined air emission factor for the identified pollutants from the local refining technology in the region. The operational sites of these refineries are inaccessible due to security and proximity to raw material, making air quality evaluation and management impossible. However, Emission Factors are one of the best ways to quantify an activity-related air pollution especially in difficult terrain like those of the artisanal refineries. In this regard, air emissions resulting from the operation of these refineries were characterized/quantified with the use of E8500 Portable Industrial Combustion Analyzer. The measured concentrations were used to calculate the emission factors and emission rates for the identified air pollutants. The overall combined emission factors (g/kg) estimated in percentage of emissions for the pollutants characterized at the various unit operation, showed that; at the Oven Heating/Crude Oil Boiling Unit, HC had 52%, 41% for CO, 3% for NOx (NO + NO2), 2% for SO2 and 2% for H2S. Other process units emitted 53% and 55% for HC, 40% and 38% for CO, all 3% for NOx, all 2% for SO2 and all 2% for H2S for the Vapour Condensation and Refined Products Collection Units respectively. It therefore concluded that the high emission factors observed from the activities of these local petroleum refineries could be a contributing factor to the degraded air quality of the region.

Risk Factors for Oronasal Fistula in Primary Palatoplasty: A Case-Control Study From a Reference Center in Medellín, Colombia.

Oronasal fistula is one of the most critical complications in primary palatoplasty, with a reported incidence between 5% and 46% with multiple associated risk factors described previously. In addition, in more than half of the patients, it implies additional surgeries, increasing risks for the patient and health care costs. In this case-control study, the authors aim to determine the specific risk factors for oronasal fistula after primary palatoplasty in the study population. A retrospective review was undertaken to identify all patients undergoing primary palatoplasty between 2017 and 2019. Patients who developed oronasal fistula were included (cases) and compared with patients from the same cohort without fistula (controls). Demographic, clinical, and perioperative variables and their association with postoperative fistula presentation were explored through crude and adjusted analysis. One hundred thirty-nine patients with a median age of 6 years (5-6) who underwent primary palatoplasty were found. Forty-five presented an oronasal fistula, corresponding to 32% of the population, and 64% required subsequent repair of an oronasal fistula. In the crude analysis, the surgeon's experience (OR: 0.44) was associated significantly with the outcome. Adjusted analysis showed an association between surgical site infection and syndromic presentation. The experience of the surgeon is a protective factor for the oronasal fistula presentation; in addition, the presentation of infection of the operative site, the syndromic presentation, and the clinical follow-up at 1 year were also relevant; the latter, possibly due to the social context of our patients.

Vascular Complications of Endoscopic Transsphenoidal Approach to Sellar Base Lesions

Objective: Vascular complications are one of the most dangerous complications of endoscopic skull base surgeries. The aim of this study was to evaluate vascular complications of endoscopic transsphenoidal surgery in patients with sellar and parasellar lesions.
 
 Methods: Between August 1997 and July 2023, a total of 5300 patients underwent endoscopic transsphenoidal surgery for skull base lesions at Kocaeli University Faculty of Medicine, Department of Neurosurgery and Pituitary Research Center. Patients with vascular complications during and after surgery were included into the study.
 
 Results: We encountered 12 major vascular injuries, 116 epistaxis, and 50 operation site hematoma in our series.
 
 Conclusion: Major vascular injuries are the most life-threatening complicastions. They can cause high mortality. The ways to prevent these injuries seems to have high experience and to investigate preoperative vascular evaluation in detail.

Development of All-electric Discharge Device for Working String

Most of the existing pipe string discharge devices in China are suitable for drilling operations, but some auxiliary devices for surface pipe string discharge in workover operations are not mature enough, and there are some problems such as inconvenient transportation, complex structure and large area. Based on the actual situation of small workover operation site, this paper puts forward the scheme of all-electric discharge device for well site operation pipe string, determines the structure function and work flow of the discharge device, carries out structural design for three parts of the lift, conveying device and pipe rack, and analyzes and calculates the structural parameters of the device. Through the static analysis of the main force components, the rationality of the device design is verified, and its structural strength is in line with the safe range.

Analgesic Efficacy of Dexamethasone and Dexmedetomidine as an Adjuvant to Bupivacaine Infiltration in Unilateral Cleft Lip Surgery: A Randomized, Double-Blinded Study

Background: In the majority of cases, the treatment method for Cleft lip is surgery. Providing adequate pain control during and after surgery for children, is too important. Also, different methods are used for pain relief like analgesic prescription and nerve block and different adjuvants can be added to anesthetics to reduce pain.
 Aims: This trial was aimed to compare the analgesic effect of Bupivacaine with or without dexmedetomidine or dexamethasone for cleft lip surgery.
 Methods: This study is a prospective, double-blinded, randomized trial which conducted on 75 pediatrics, aged between 3 to 10 months, who needed unilateral cleft lip surgery. Patients were divided into 3 groups (n=25 in each group). Children in group A, were given a combination of bupivacaine and 0.5 µg/kg of dexmedetomidine, those in group B, 0.1 mg/kg of dexamethasone as an adjuvant to bupivacaine, and in group C, plain 1 cc of bupivacaine 0.5% was injected in the operation site. Outcomes were assessed via FLACC and WATCHA scores.
 Results: The mean age among children was 4.3 ±1.29 months and mean weight was 6.3± 1.09 kg. Pain score and frequency of analgesic request intra and post-operation in group A was lower than others (p<0.0001). Also, FLACC and WATCHA scores were significantly lower in group A (p<0.0001) and parental and surgeon satisfaction was higher in group A (p<0.05).
 Conclusion: Our study showed that, dexmedetomidine as an adjuvant to bupivacaine 0.5% is more effective to improve the analgesia, in children who underwent unilateral cleft lip surgery.

Lunar rock investigation and tri-aspect characterization of lunar farside regolith by a digital twin

Yutu-2 rover conducted an exciting expedition on the 41st lunar day to investigate a fin-shaped rock at Longji site (45.44°S, 177.56°E) by extending its locomotion margin on perilous peaks. The varied locomotion encountered, especially multi-form wheel slippage, during the journey to the target rock, established unique conditions for a fin-grained lunar regolith analysis regarding bearing, shear and lateral properties based on terramechanics. Here, we show a tri-aspect characterization of lunar regolith and infer the rock’s origin using a digital twin. We estimate internal friction angle within 21.5°−42.0° and associated cohesion of 520-3154 Pa in the Chang’E-4 operational site. These findings suggest shear characteristics similar to Apollo 12 mission samples but notably higher cohesion compared to regolith investigated on most nearside lunar missions. We estimate external friction angle in lateral properties to be within 8.3°−16.5°, which fills the gaps of the lateral property estimation of the lunar farside regolith and serves as a foundational parameter for subsequent engineering verifications. Our in-situ spectral investigations of the target rock unveil its composition of iron/magnesium-rich low-calcium pyroxene, linking it to the Zhinyu crater (45.34°S, 176.15°E) ejecta. Our results indicate that the combination of in-situ measurements with robotics technology in planetary exploration reveal the possibility of additional source regions contributing to the local materials at the Chang’E-4 site, implying a more complicated geological history in the vicinity.

Prevalence and Determinants of Post - Operative Surgical Site Infections at Amana Regional Referral Hospital, Tanzania: A Prospective Observational Study

Prevalence and Determinants of Post - Operative Surgical Site Infections at Amana Regional Referral Hospital, Tanzania: A Prospective Observational Study