Matrix Metalloproteinases-8 and-9 and Tissue Inhibitor of Metalloproteinase-1 in Burn Patients. A Prospective Observational Study

Introduction Matrix metalloproteinases (MMPs) -8 and -9 are released from neutrophils in acute inflammation and may contribute to permeability changes in burn injury. In retrospective studies on sepsis, levels of MMP-8, MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) differed from those of healthy controls, and TIMP-1 showed an association with outcome. Our objective was to investigate the relationship between these proteins and disease severity and outcome in burn patients. Methods In this prospective, observational, two-center study, we collected plasma samples from admission to day 21 post-burn, and burn blister fluid samples on admission. We compared MMP-8, -9, and TIMP-1 levels between TBSA20% (N = 30) injured patients and healthy controls, and between 90-day survivors and non-survivors. MMP-8, -9, and TIMP-1 levels at 24-48 hours from injury, their maximal levels, and their time-adjusted means were compared between groups. Correlations with clinical parameters and the extent of burn were analyzed. MMP-8, -9, and TIMP-1 levels in burn blister fluids were also studied. Results Plasma MMP-8 and -9 were higher in patients than in healthy controls (P20% groups. MMP-8 and -9 were not associated with clinical severity or outcome measures. TIMP-1 differed significantly between patients and controls (P20% groups (PPeer reviewe

Nasal sound pressure as objective verification of implant in active transcutaneous bone conduction devices

Sabine Reinfeldt,1 Cristina Rigato,1 Bo Håkansson,1 Karl-Johan Fredén Jansson,1 Måns Eeg-Olofsson21Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden; 2Department of Otorhinolaryngology, Head and Neck Surgery, Sahlgrenska University Hospital, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, SwedenObjective: Active transcutaneous bone conduction devices consist of an external audio processor and an internal implant under intact skin. During the surgical procedure, it is important to verify the functionality of the implant before the surgical wound is closed. In a clinical study with the new bone conduction implant (BCI), the functionality of the implant was tested with an electric transmission test, where the output was the nasal sound pressure (NSP) recorded in the ipsilateral nostril. The same measurement was performed in all follow-up visits to monitor the implant’s functionality and transmission to bone over time. The objective of this study was to investigate the validity of the NSP method as a tool to objectively verify the implant’s performance intraoperatively, as well as to follow-up the implant’s performance over time.Design: Thirteen patients with the BCI were included, and the NSP measurement was part of the clinical study protocol. The implant was electrically stimulated with an amplitude-modulated signal generator using a swept sine 0.1–10 kHz. The NSP was measured with a probe tube microphone in the ipsilateral nostril.Results: The NSP during surgery was above the noise floor for most patients within the frequency interval 0.4–5 kHz, showing NSP values for expected normal transmission of a functioning implant. Inter-subject comparison showed large variability, but follow-up results showed only minor variability within each subject. Further investigation showed that the NSP was stable over time.Conclusion: The NSP method is considered applicable to verify the implant’s functionality during and after surgery. Such a method is important for implantable devices, but should be simplified and clinically adapted. Large variations between subjects were found, as well as smaller variability in intra-subject comparisons. As the NSP was found to not change significantly over time, stable transmission to bone, and implant functionality, were indicated.Keywords: bone conduction, nasal sound pressure, bone conduction implant, ear-canal sound pressure, objective intraoperative verificatio

Robustness and lifetime of the bone conduction implant – a pilot study

Karl-Johan Fredén Jansson,1 Bo Håkansson,1 Cristina Rigato,1 Måns Eeg-Olofsson,2 Sabine Reinfeldt1 1Department of Electrical Engineering, Chalmers University of Technology, Göteborg, Sweden; 2Department of Otorhinolaryngology, Head and Neck Surgery, Sahlgrenska University Hospital, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Objectives: The objective of this study was to develop methods for evaluating the mechanical robustness and estimating the lifetime of the novel bone conduction implant (BCI) that is used in a clinical study. The methods are intended to be applicable to any similar device.Materials and methods: The robustness was evaluated using tests originally developed for cochlear implants comprising a random vibration test, a shock test, a pendulum test, and an impact test. Furthermore, magnetically induced torque and demagnetization during magnetic resonance imaging at 1.5 T were investigated using a dipole electromagnet. To estimate the lifetime of the implant, a long-term age-accelerated test was performed.Results: Out of all the tests, the pendulum and the impact tests had the largest effect on the electro-acoustic performance of the BCI implant, even if the change in performance was within acceptable limits (<20%). In comparison with baseline data, the lower and higher resonance peaks shifted down in frequency by 13% and 18%, respectively, and with a loss in magnitude of 1.1 and 2.0 dB, respectively, in these tests.Conclusion: A complete series of tests were developed, and the BCI passed all the tests; its lifetime was estimated to be at least 26 years for patients who are using the implant for 12 hours on a daily basis. Keywords: audiology, bone conduction audiometry, electromagnetic transducer, electro-acoustic

Magnetic resonance imaging investigation of the bone conduction implant – a pilot study at 1.5 Tesla

Karl-Johan Fredén Jansson,1 Bo Håkansson,1 Sabine Reinfeldt,1 Cristina Rigato,1 Måns Eeg-Olofsson2 1Department of Signals and Systems, Chalmers University of Technology, 2Deptartment of Otorhinolaryngology Head and Neck Surgery, Sahlgrenska University Hospital, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Purpose: The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated.Methods and materials: One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI.Results: It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant.Conclusion: This pilot study indicates that the present BCI may withstand 1.5 Tesla MRI with only minor effects on its performance. No MRI induced sound was reported, but the head image was highly distorted near the implant.Keywords: bone conduction implant (BCI), magnetic resonance imaging (MRI), image artifacts, demagnetization, magnetic torqu

Cutaneous steam burns and steam inhalation injuries : a literature review and a case presentation

Scald is one type of burn that s often mentioned alone and occurs mostly in the paediatric population. Inhaled steam is mostly cooled off in the airways, why thermal damage is rarely seen. A sudden exposure to hot steam/inhalation can cause a thermal inhalation injury. A scoping review was performed, with the aim to summarize all published papers in English, about steam-related injuries. The search was conducted using the PubMed (R) and Cochrane libraries on 19th of May 2021, without a set time period. Out of a total of 1186 identified records, 31 were chosen for review. Burns related to the contact with steam are generally rare and can be both minor and severe. The more severe cases related to steam exposure are mostly workplace accidents and the minor injuries reported in the literature are often related to steam inhalation therapy, especially in the paediatric population. This review describes the challenges that can be found dealing with patients suffering from cutaneous steam burns and/or steam inhalation injuries. A steam injury to the airways or the skin can be directly life-threatening and should be treated with caution. This type of injury can lead to acute respiratory insufficiency and sometimes death. A case of a male patient with extensive cutaneous steam burns and a steam inhalation injury who passed away after 11 days of treatment is also presented to illustrate this review. Level of evidence: Level V, Therapeutic; Risk/Prognostic Study