A comparison of technicques to disimpact the fetal head on a second stage caesearean simulator.

BACKGROUND: The rate of second stage caesarean section (CS) is rising with associated increases in maternal and neonatal morbidity, which may be related to impaction of the fetal head in the maternal pelvis. In the last 10 years, two devices have been developed to aid disimpaction and reduce these risks: the Fetal Pillow (FP) and the Tydeman Tube (TT). The aim of this study was to determine the distance of upward fetal head elevation achieved on a simulator for second stage CS using these two devices, compared to the established technique of per vaginum digital disimpaction by an assistant. METHODS: We measured elevation of the fetal head achieved with the two devices (TT and FP), compared to digital elevation, on a second stage Caesearean simulator (Desperate Debra ™ set at three levels of severity. Elevation was measured by both a single operator experienced with use of the TT and FP and also multiple assistants with no previous experience of using either device. All measurements were blinded RESULTS: The trained user achieved greater elevation of the fetal head at both moderate and high levels of severity with the TT (moderate: 30mm vs 12.5mm p<0.001; most severe: 25mm vs 10mm p<0.001) compared to digital elevation. The FP provided comparable elevation to digital at both settings (moderate: 10 vs 12.5mm p=0.149; severe 10 vs 10mm p=0.44). With untrained users, elevation was also significantly greater with the TT compared to digital elevation (20mm vs 10mm p<0.01). However digital disimpaction was significantly greater than the FP (10mm vs 0mm p<0.0001). CONCLUSION: On a simulator, with trained operators, the TT provided greater fetal head elevation than digital elevation and the FP. The FP achieved similar elevation to the digital technique, especially when the user was trained in the procedure.

Reloadable Stapler Use during Peripartum Hysterectomy for Placenta Accreta Spectrum: A Novel Surgical Technique and Case Series.

OBJECTIVE: This study aimed to describe a novel surgical technique for the management of antenatally suspected placenta accreta spectrum (PAS). STUDY DESIGN: This is a retrospective, case series of patients with suspected PAS undergoing peripartum hysterectomy with a reloadable articulating stapler at a tertiary care center. RESULTS: Eighteen patients with antenatally suspected PAS were identified and underwent peripartum hysterectomy with the aid of a reloadable stapler. Mean gestational age at delivery was 344/7 ± 11/7 weeks. Mean total operative time (skin-to-skin) was 117.3 ± 39.3 minutes, and 79.8 ± 19.8 minutes for the hysterectomy. Mean blood loss for the entire case was 1,809 ± 868 mL. Mean blood loss for the hysterectomy was 431 ± 421 mL. Mean units of intraoperative red blood cells transfused was 3 ± 1 units. Mean units of postoperative red blood cells transfused was 1 ± 0.5 units. Five cases were complicated by urological injury (two intentional cystotomies). Four patients were admitted to the intensive care unit (ICU) for a mean of ≤24 hours. Mean postoperative LOS was 4.11 ± 1.45 days. Three patients had final pathology that did not demonstrate PAS while four were consistent with accreta, six increta, and five percreta. CONCLUSION: Use of a reloadable articulating stapler device as part of the surgical management of antenatally suspected PAS results in a shorter operative time (117 ± 39 minutes vs. 140-254 minutes previously reported), lower average blood loss (1,809 ± 868 mL vs. 2,500-5,000 mL previously reported) and shorter LOS (4.11 ± 1.45 days vs. 9.8 ± 13.5 days previously reported) compared with traditional cesarean hysterectomy. The reloadable stapling device offers an advantage of more rapidly achieving hemostasis in the surgical management of PAS. KEY POINTS: · PAS is associated with severe maternal morbidity.. · Decreased operative time and blood loss have many clinical benefits.. · Reloadable stapler use for PAS decreases operative time.. · Reloadable stapler use for PAS decreases operative blood loss..

Needle in the heart: a rare case of cardiac tamponade caused by a migrated foreign body and mimicking ST segment elevation myocardial infarction.

BACKGROUND: Pericardial tamponade is a serious condition which may eventually lead to severe haemodynamic disturbances and cardiac arrest. It is most often caused by the accumulation of fluid inside the pericardium, as a result of different aetiological factors such as pericarditis, neoplastic diseases, lymphatic dysfunctions, or idiopathic pericardial disease. Pericardial tamponade can develop after cardiac surgical procedures or as a complication of myocardial infarction. Collection of blood inside the pericardial sack can be the result of pericardial or cardiac trauma. It is exceedingly rare for the injury to be caused by a migrating foreign body. Although a typical picture of pericardial tamponade has been previously described, the disorder may clinically resemble an acute myocardial infarction. CASE PRESENTATION: We report the case of a 58-year-old female patient complaining of new onset thoracic pain and shortness of breath. Electrocardiographic examination results were suggestive of an acute inferior myocardial infarction. However, echocardiography revealed significant pericardial tamponade. The cause was found to be a needle which remained inside the pelvis following a previous cesarean delivery, which the patient had undergone 18 years prior. In emergency setting, the needle was removed and the pericardial tamponade was resolved. Due to the prompt and efficient management, the patient had an uneventful postoperative recovery and presented no recurrence at the follow-up examinations. CONCLUSIONS: The migration of foreign bodies through tissues is exceedingly rare. If present, it may cause life-threatening complications. Since the aetiology of pericardial tamponade is vast, a thorough assessment is highly important. Therefore, echocardiography is the imaging modality of choice. We wish to highlight the possibility of migrating foreign bodies as probable cause for pericardial tamponade, as well as the importance of echocardiographic methods in the fast-track evaluation of such critical conditions.

Effectiveness of the fetal pillow to prevent adverse maternal and fetal outcomes at full dilatation cesarean section in routine practice.

INTRODUCTION: The fetal pillow has been suggested to reduce maternal trauma and fetal adverse outcomes when used to disimpact the fetal head at full dilatation cesarean section. MATERIAL AND METHODS: We performed a retrospective cohort study of the use of the fetal pillow device at full dilatation cesarean section between September 2014 and March 2018 at Liverpool Women's Hospital, a large UK teaching hospital. RESULTS: There were 471 cases of full dilatation cesarean section during the study period and 391 were included for the analysis; 170 used the fetal pillow and 221 were delivered without. We did not demonstrate any benefit in the significant maternal outcomes of estimated blood loss >1000 mL or >1500 mL, need for blood transfusion, or duration of hospital stay, from the use of the fetal pillow. We did not demonstrate any improvement in fetal outcome following use of the fetal pillow for arterial pH <7.1, Apgar score <7 at 5 minutes or admission to the neonatal unit. For deliveries undertaken at or below the level of the ischial spines there was likewise no benefit from fetal pillow use, except in a reduced risk of an arterial pH <7.1 (relative risk 0.39, 95% CI 0.20-0.80, P = .01); however, admission to the neonatal unit was unaffected. CONCLUSIONS: This is the largest study to date on the use of the fetal pillow at full dilatation cesarean section. We did not demonstrate any statistically significant benefit from the use of the fetal pillow to prevent any maternal or fetal adverse outcomes at full dilatation cesarean section in routine clinical use. Further randomized studies are required to prove clinical benefit from this device before more widespread use.

Cesarean section scar in 3 T magnetic resonance imaging and ultrasound: image characteristics and comparison of the methods.

PURPOSE: Uterine rupture during labor is a rare but life-threatening complication after previous cesarean section (CS). Prenatal risk is assessed using ultrasound thickness measurement of the lower uterine segment (LUS). Due to inhomogeneous study results, however, clinical obstetrics still lacks for standard protocols and reliable reference values. As 3 T magnetic resonance imaging (MRI) has not yet been sufficiently studied regarding LUS diagnostics after previous CS, we sought to evaluate its feasibility focusing on thickness measurements and typical characteristics of the CS-scar region in comparison to ultrasound and the intraoperative status. METHODS: In this prospective study, 25 asymptomatic patients with one previous CS and inconspicuous ultrasound findings were included. An additional 3 T MRI with either a T2-weighted Turbo-Spin-Echo or a Half Fourier-Acquired-Single-shot-Turbo-spin-Echo sequence in a sagittal orientation was performed. We analyzed categorical image quality, inter- and intra-rater reliability as well as anatomy, morphology and thickness of the LUS. Results were compared to ultrasound and intraoperative findings. RESULTS: MRI provided good to excellent image quality in all patients. The imaged structures presented with a high variability in anatomy and morphology. Image characteristics indicating the uterine scar were only found in 11/25 (44%) patients. LUS thickness measurements with MRI showed good inter- and intra-rater reliability but poor agreement with ultrasound. CONCLUSIONS: MRI is appropriate for additional LUS diagnostics in patients with previous CS. The strong individual variability of LUS-anatomy and morphology might explain the difficulties in establishing uniform diagnostic standards after CS.

Scalpel versus diathermy skin incision in Caesarean section.

Surgical scalpels are traditionally used for skin incisions during a Caesarean delivery; the great evolutions in electrosurgical devices bring an alternative method for skin incision by the usage of cutting diathermy. This was a prospective randomised comparative study conducted during the period from March 2016 to February 2017 on 200 patients, 100 patients had skin incisions using the surgical scalpel, while 100 patients had skin incisions with a diathermy, in order to judge the variations in the postoperative pain, the incision time, the incision blood loss, the operative time, the wound healing and the wound complications. We observed a significant difference between the two groups regarding the incision time (p < .001), incisional blood loss (p < .001), operative time (p < .001) and the postoperative pain (p < .001), where these parameters were less in the diathermy group. No significant difference observed between the two groups regarding the wound healing (p = .389) and wound complications (p = .470). We can conclude that the proper usage of diathermy in making the skin incision during a Caesarean section in this study achieved better results than the scalpel incision. Impact statement What is already known on this subject? Surgical scalpels are traditionally used in making the skin incisions during a Caesarean section; diathermy incisions, on the contrary, are less popular among the surgeons. It has been hypothesised that the application of extreme heat may result in a significant postoperative pain and poor wound healing. There has been a widespread use of diathermy for hemostasis but fear of production of large scars and improper tissue healing has restricted their usage in making skin incisions. What do the results of this study add? The use of diathermy for skin incisions in Caesarean section in this study was associated with a reduced incisional blood loss, incisional time, operative time and postoperative pain. It had no effect on wound closure and was not associated with any delay in wound healing. Also, the wound complications rate was equal in both types of incisions. What are the implications of these findings for clinical practice and/or further research? Most surgeons prefer the scalpel in making skin incision during a Caesarean section due to the fear of surgical site infection. Our findings proved different, we proved that cutting diathermy could be accepted as an alternative technique for making a skin incision without increased rates of wound infections. Also, the advantages of cutting diathermy will give benefits to both the patients and the surgeons.

Does Preprocedural Ultrasound Increase the First-Pass Success Rate of Epidural Catheterization Before Cesarean Delivery? A Randomized Controlled Trial.

BACKGROUND: Preprocedural ultrasound may improve the efficacy and safety of epidural catheterization, especially in difficult cases. Most studies of ultrasound-assisted epidural catheterization in the obstetric population are dated and nonblinded with inconsistent designs. This double-blind, randomized controlled study aimed to compare the ultrasound-assisted with the conventional palpation techniques for epidural catheterization in parturients undergoing cesarean delivery. We hypothesized that the use of preprocedural ultrasound would increase the success rate of epidural catheterization at the first needle pass. METHODS: Eligible subjects were American Society of Anesthesiologists physical status II parturients with full-term singleton pregnancy undergoing elective cesarean delivery using double-interspace combined spinal-epidural anesthesia. Exclusion criteria were age <19 or >40 years, body mass index ≥35 kg/m, women presenting in labor or having any contraindication to neuraxial anesthesia, marked spinal deformity, previous spinal surgery, or impalpable anatomical landmarks. One hundred ten patients were randomly allocated into 2 equal groups (palpation and ultrasound groups). All procedures were performed by a single experienced anesthesiologist. Patients and investigators assessing the outcome data were blinded to group allocation. A systematic spinal ultrasound assessment and a sham procedure were performed in the ultrasound and palpation groups, respectively, before attempting epidural catheterization. The primary outcome was the rate of successful epidural catheterization at the first needle pass. Secondary outcomes were the rate of successful epidural catheterization at the first skin puncture, number of performed needle passes and skin punctures, duration of the epidural procedure, patient satisfaction from the procedure, and complications of the procedure (incidence of unintentional dural and vascular punctures, failed block, unilateral or patchy block, and backache). RESULTS: Data from 108 patients (55 patients in the palpation group and 53 patients in the ultrasound group) were analyzed. The rate of successful epidural catheterization at the first needle pass was 60% in the palpation group and 58.5% in the ultrasound group (95% confidence interval of the difference in proportions between groups is -18.5% to 21.6%; P > 0.99). There were no significant differences between the 2 groups in the success rate at the first skin puncture, the number of needle passes and skin punctures, or patient satisfaction. The median (range) duration of the epidural procedure was 185 (57-680) seconds in the ultrasound group and 215 (114-720) seconds in the palpation group (P = 0.036 with the Mann-Whitney U test and P = 0.083 with the Student t test with unequal variances). The overall rate of complications of the procedure was low in both groups. CONCLUSIONS: For experienced anesthesiologists, it remains unclear whether preprocedural ultrasound improves the epidural catheterization technique in parturients with palpable anatomical landmarks undergoing cesarean delivery.

Assessment of a vaginal device for delivery of the impacted foetal head at caesarean section.

The aim of this study was to assess a new device (Tydeman Tube) designed to facilitate delivery of the impacted foetal head at caesarean section. Standard digital vaginal technique and the Tydeman Tube were each used to elevate the foetal head on a validated full dilatation caesarean simulator. Greater elevation of the foetal head was achieved with the Tydeman Tube than digital technique (mean difference +9.1 mm, p < 0.001). Although greater force was applied to achieve this elevation (mean difference +0.42 Kgf, p < 0.001), the force was spread over a greater area (6.97 cm2 versus 2.0 cm2). Therefore, mean pressures applied to the foetal head were lower (mean difference -2.3 Kg cm2, p < 0.001). The first uses of the Tydeman Tube in clinical practice were described. Clinicians found it easy to use and effective (mean score 7.7/10). The Tydeman Tube is an effective tool for delivering the impacted foetal head on a simulator and its initial use in clinical practise has proved positive.

A randomized controlled trial comparing two types of retractors at caesarean delivery.

The aim of this study was to determine if the use of a self-retaining, symmetrical retractor (OB/Mobius®) during caesarean delivery is associated with differences in post-operative pain experience. Consenting women undergoing caesarean delivery were randomly assigned to OB/Mobius® versus conventional retraction instruments. Women were blinded to retractor type and filled out surgical pain surveys each post-operative day. Additional outcome variables were collected through a provider survey and chart review. Of the 154 randomised women, 144 completed the study. There was no difference in the symmetry, quality or intensity of postoperative pain based on the method of retraction. The OB/Mobius® retractor did not confer an improvement in the quality or intensity of post-caesarean discomfort in the first three days following delivery. Nor did the groups differ in operative times, blood loss or pain medication usage. However, the retractor may offer improved visualisation and retraction in obese women. Impact statement Use of a plastic sheath self-retaining retractor has been minimally studied in caesarean deliveries. Recently it was found that the use of such a retractor reduced wound infection, but another study in obese women did not show improved rates of infection (Hinkson et al. 2016 ; Scolari Childress et al. 2016 ). The study of sheath self-retaining retractors to decrease post-operative pain has not been reported previously. This study offers an investigation into a generalisable population of parturients who undergo caesarean delivery and if the primary use of a self-retaining retractor versus sole use of traditional hand-held retractors decreased post-operative pain while in the hospital. Although this study did not show an improvement in post-operative pain, provider experience reports demonstrated some improvement in visualisation, particularly in the obese population with the use of this novel retractor, thus making it an option for providers who do caesarean deliveries without an assistant and find hand-held retractors inadequate.

Medical Devices; Obstetrical and Gynecological Devices; Classification of the Fetal Head Elevator. Final order.

The Food and Drug Administration (FDA or we) is classifying the fetal head elevator into class II (special controls). The special controls that apply to the device type are identified in this order and will be part of the codified language for the fetal head elevator's classification. We are taking this action because we have determined that classifying the device into class II (special controls) will provide a reasonable assurance of safety and effectiveness of the device. We believe this action will also enhance patients' access to beneficial innovative devices, in part by reducing regulatory burdens.

A barrier retractor to reduce surgical site infections and wound disruptions in obese patients undergoing cesarean delivery: a randomized controlled trial.

BACKGROUND: Surgical site infections (SSIs) are an important cause of morbidity following cesarean delivery, particularly in obese patients. Methods to reduce SSIs after cesarean delivery would have an important impact in obese obstetric patients. OBJECTIVE: The purpose of this study was to determine whether the Alexis O cesarean delivery retractor, a barrier self-retaining retractor, reduces SSIs and wound disruptions in obese patients undergoing cesarean delivery. STUDY DESIGN: This was a randomized controlled trial of obese women (body mass index ≥ 30 kg/m(2)) undergoing nonemergent cesarean delivery. Patients were randomized to the treatment group (using the Alexis O cesarean delivery retractor) or to the control group (using conventional handheld retractors). The primary outcome was SSI or wound disruption during the 30 day postoperative period. Secondary outcomes included operative time, estimated blood loss, change in hemoglobin, antiemetic use, length of postoperative hospital stay, hospital readmission, and other postoperative complications. RESULTS: A total of 301 patients were enrolled in the study. One hundred forty-four patients were randomized to the treatment group and 157 to the control group. Baseline characteristics and indications for cesarean delivery were similar between the 2 groups. Median body mass index was 40.1 kg/m(2). There were no significant differences between the treatment and the control group in the primary outcome of SSI or wound disruption rates at the 30 day assessment (20.6% vs 17.6%, P = .62), during the postoperative inpatient hospitalization or at the 1-2 week postoperative visit. There were also no differences in the primary outcome when adjusting for obesity class or thickness of the subcuticular layer. Patients in the treatment group had lower rates of uterine exteriorization (54.3% vs 87.3%, P < .001), but there were no differences in all other outcomes. CONCLUSION: Use of the Alexis retractor in cesarean delivery deliveries did not decrease SSI or wound disruption rates in an obese population. Its use as a retractor should be left to the discretion of the surgeon and clinical circumstances.

What are the best surgical techniques for caesarean sections? A contemporary review.

The aim of this study was to evaluate the reported techniques used in caesarean sections in order to form a general perspective of the procedural options for this frequently performed operation. The PubMed database and Cochrane Reviews were searched separately with the key words 'caesarean', 'abdominal entry', 'abdominal incision', 'uterine repair', 'peritoneal repair', 'closure of abdominal incision', 'suture materials', 'extraction of the placenta' and 'review'. Reviews, meta-analyses and prospective randomised trials were included in this review. In conclusion, although caesarean delivery is a very common operation, standardised and globally accepted techniques for caesarean section have not been described. The best surgical techniques for this operation are still unknown. Although the long-term follow-up results from two large, prospective, randomised studies are pending, further research is needed to establish an evidence-based, standardised approach for caesarean sections.

Assessment of an updated double-vasopressor automated system using Nexfin for the maintenance of haemodynamic stability to improve peri-operative outcome during spinal anaesthesia for caesarean section.

Hypotension occurs commonly during spinal anaesthesia for caesarean section, associated with maternal and fetal adverse effects. We developed a double-vasopressor automated system with a two-step algorithm and continuous non-invasive haemodynamic monitoring using the Nexfin device. The system delivered 25 µg phenylephrine every 30 s when systolic blood pressure was between 90% and 100% of baseline, or 2 mg ephedrine at this blood pressure range and heart rate < 60 beats.min(-1) ; and 50 µg phenylephrine or 4 mg ephedrine when systolic blood pressure was < 90% of baseline with the same heart rate criterion. Fifty-seven women received standardised spinal anaesthesia. Twenty-seven (47.4%) had at least one reading of hypotension defined as systolic blood pressure < 80% baseline. Systolic blood pressure was within 20% of the baseline in a mean (SD) of 79.8 (20.9)% of measurements. Fifty-three (93.0%) women required phenylephrine before delivery while 10 (17.5%) required ephedrine. Six women (10.5%) experienced nausea and three (5.3%) vomited. The system was able to achieve a low incidence of maternal hypotension with good maternal and fetal outcomes.

Does elevating the fetal head prior to delivery using a fetal pillow reduce maternal and fetal complications in a full dilatation caesarean section? A prospective study with historical controls.

A caesarean section at full dilatation (CSFD) can be technically demanding and has consistent association with increased intraoperative trauma. There is evidence that the incidence of caesarean sections at full dilation is on the rise. We report on a prospective study of 50 women undergoing CSFD using a fetal pillow (FP) to elevate the fetal head. Data were compared with historical controls of 124 women without FP use on uterine extensions, uterine incision delivery interval, blood loss, need for transfusion, operating time, length of stay, intensive care unit admission. The FP elevated the fetal head in all 50 women (p < 0.001). We found that patients in the FP group had a lower incidence of extensions (p = 0.03), shorter operating time (p < 0.001), uterine incision to delivery interval (p < 0.001) and shorter length of hospital stay (p < 0.001). Blood loss > 1,000 ml and admission to ICU was also lower but were not statistically significant. There were no significant differences in the fetal complications studied, APGAR scores, admission to neonatal intensive care unit, seizures, neonatal injury or death.

A randomized trial comparing metallic and absorbable staples for closure of a Pfannenstiel incision for cesarean delivery.

OBJECTIVE: The purpose of the study is to compare postoperative pain, cost, speed of closure, and patient satisfaction of Pfannenstiel skin incisions closed with traditional metallic staples vs absorbable staples after cesarean delivery. It is hypothesized that incisions closed with absorbable staples will cause less postoperative pain than traditional metallic staples. STUDY DESIGN: A randomized, controlled trial was conducted from July 2010 through May 2011. Patients undergoing a scheduled cesarean delivery via a Pfannenstiel skin incision were recruited. Patients were randomized into the control group (metallic staples) or the experimental group (absorbable staples). The postpartum nurse and patient were blinded to the type of staples. Postoperative pain was assessed using a visual analog scale on both postoperative day 1 and day of discharge, and the total dose of oral narcotics taken during the postoperative period was assessed. RESULTS: In all, 100 patients enrolled in the study: 50 in each group. Based on visual analog scale scores, there were no significant differences between the 2 groups on postoperative day 1 or day of discharge. There were no significant differences in the total dose of oral narcotics taken or in wound complication rates. The time for skin closure was significantly different: 3.5 ± 1.7 for absorbable and 1.39 ± 0.7 minutes for metallic staples (P < .0001). The calculated cost of each device, including placement and removal, was $285.60 for the absorbable and $150.79 for the metallic staples. CONCLUSION: Postoperative pain is comparable for both devices. The absorbable staple skin closure time, and therefore cost, is significantly greater than for metallic staples.

Cesarean delivery in the hybrid operating suite: a promising new location for high-risk obstetric procedures.

BACKGROUND: The increasing cesarean delivery rate and attendant placental implantation abnormalities, coupled with increasing general medical complexity in the obstetric population, has driven innovation to optimize the care of high-risk parturients during delivery. Novel and multidisciplinary approaches and locations may enhance the options available for care. METHODS: We reviewed the records of all 11 patients who underwent cesarean delivery in our hybrid operating suite between December 2007 and March 2013 and describe the high-risk cesarean deliveries. RESULTS: The most common indication for the use of the hybrid operating suite was an increased risk of hemorrhage, most commonly due to abnormal placental implantation. Other indications included cardiovascular disease and intracranial pathology. CONCLUSION: The hybrid operating suite may be an alternative location for obstetric delivery, and our experience suggests that this environment may prove advantageous for patients with a variety of comorbid conditions.

A simple device prevents hysterotomy extensions during cesarean delivery for failed second stage of labor.

BACKGROUND/AIMS: [corrected] During arrest of descent, maternal tissues conform to the fetal head, resulting in a suction-cup like effect during cesarean delivery. We hypothesize that breaking this suction might ease delivery. A novel device was designed for this purpose and tested in this series of 23 patients. METHODS: University-based retrospective cohort feasibility study. Term pregnant women with second-stage labor arrest (n = 23) provided written consent for use of the experimental device, inserted vaginally prior to cesarean delivery. Delivering obstetricians rated device effectiveness. Following case collection, the presence of hysterotomy extensions in study patients was retrospectively compared with controls (n = 49) from the same study period. RESULTS: On a 7-point Likert scale, consultant obstetricians rated overall device effectiveness as 6.0, and resident obstetricians rated it 6.3, consistent with a moderate improvement in ease of delivery. The device performed optimally at mid-pelvic stations (0 to +1), with no hysterotomy extensions (n = 0/17), which was significantly better than controls (n = 14/41, 34%, p < 0.01). CONCLUSION: A simple device prevented hysterotomy extension during second-stage cesarean delivery at 0 and +1 station. Obstetricians perceived that the device afforded a moderate improvement in delivery compared with previous deliveries in which the device was not used.