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Blood Flow Dynamics in Burns
Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences.
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Objectives:

Burns of intermediate thickness are hard to evaluate clinically. This often leads to unnecessary delays of up to 14 days before a surgical decision can be made. To counter this, several objective methods have been developed to determine the healing potential of the wound. Over the years, measurement of perfusion has proven to be the most successful method for evaluation of healing potential. Laser Doppler imaging (LDI) is currently the most used method and can determine surgical need 2 days after injury with an accuracy >90%.  

There are however emerging techniques like laser speckle contrast imaging (LSCI), which also measure perfusion. LSCI have several advantages over LDI and is easier to use. LSCI can also investigate aspects of the microcirculation, previously not possible with LDI. The aim of this thesis was to investigate LSCI’s ability to evaluate surgical need in burns of indeterminate partial-thickness.  

The first objective was to investigate the dynamics of perfusion the first 14 days after injury. The purpose was to find the optimal time-window for perfusion measurements. The next goal was to determine the accuracy of different perfusion cut-offs. In this second study, the benefit of a subsequent measurement was also investigated. After this, interobserver variation between different profession groups was studied. Both the agreement of perfusion measurements and observer assessments were evaluated. Finally, cardiac vasomotion in combination with perfusion (pulsatility) was investigated as a method to determine surgical need <48 hours after injury.  

Methods:

Perfusion was measured in a total of 77 patients at the Department of Plastic Surgery, Hand Surgery and Burns at Linköping University Hospital, Sweden. Most of these patients were children and the most common type of burn was scalds. A laser speckle contrast imager (PeriCam PSI System, Perimed AB, Järfälla, Sweden) was used to measure perfusion.  

Results:  

In the first paper we showed a clear relation between perfusion dynamics and the healing potential of the wound. The changes in perfusion were largest the first 5 days after injury, why this time interval was selected for subsequent papers. Perfusion measurements done day 3-4 after injury could predict surgical need with a sensitivity of 100% (95% CI: 83.9-100%) and a specificity of 90.4% (95% CI: 83.8-94.9%). If two measurements were used, <24 hours and 3-4 days after injury, the accuracy was 100%. Furthermore, we found that different observers could consistently predict perfusion, while there was a large variation in their clinical assessments. This was not improved by extensive burn experience. Finally, pulsatility could be used to predict surgical need the same day as the injury occurred with a sensitivity of 100% (95% CI: 88.1-100%) and a specificity of 98.8% (95% CI: 95.7- 99.9%).  

Conclusions:  

LSCI is a promising method for evaluation of burns and provides several benefits over LDI. The surgical need of burns can be determined mere hours after injury when pulsatility is measured. However, the benefits of early scald diagnostics in children with LSCI need to be evaluated in a prospective study before the method is ready for routine clinical use.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2019. , p. 83
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1720
National Category
Medical Laboratory and Measurements Technologies
Identifiers
URN: urn:nbn:se:liu:diva-162216DOI: 10.3384/diss.diva-162216ISBN: 9789179299453 (print)OAI: oai:DiVA.org:liu-162216DiVA, id: diva2:1372619
Public defence
2019-12-20, Berzeliussalen, Campus US, Linköpings Universitet, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2019-12-12Bibliographically approved
List of papers
1. Microvascular blood flow in scalds in children and its relation to duration of wound healing: A study using laser speckle contrast imaging
Open this publication in new window or tab >>Microvascular blood flow in scalds in children and its relation to duration of wound healing: A study using laser speckle contrast imaging
Show others...
2016 (English)In: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 42, no 3, p. 648-654Article in journal (Refereed) Published
Abstract [en]

Background: Microvascular perfusion changes in scalds in children during the first weeks after injury is related to the outcome of healing, and measurements of perfusion, based on laser Doppler imaging, have been used successfully to predict the need for excision and grafting. However, the day-to-day changes in perfusion during the first weeks after injury have not to our knowledge been studied in detail. The aim of this study, based on a conservative treatment model where excision and grafting decisions were delayed to day 14 after injury, was to measure changes in perfusion in scalds using laser speckle contrast imaging (LSCI) during the first three weeks after injury. Methods: We measured perfusion with LSCI in 34 patients at regular intervals between 6 h after injury until complete reepithelialization or surgery. Duration of healing was defined as the time to complete reepithelialization. Results: Less perfusion, between 6 and 96 h after injury, was associated with longer duration of healing with the strongest association occurring between 72 and 96 h. Burns that healed within 14 days had relatively high initial perfusion, followed by a peak and subsequent slow decrease. Both the maximum perfusion and the time-to-peak were dependent on the severity of the burn. Burns that needed excision and grafting had less initial perfusion and a gradual reduction over time. Conclusion: The perfusion in scalds in children shows characteristic patterns during the first weeks after injury depending on the duration of wound healing, the greatest difference between wounds of different severity being on the 4th day. Perfusion should therefore preferably be measured on the fourth day if it is to be used in the assessment of burn depth. (c) 2015 Elsevier Ltd and ISBI. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2016
Keywords
Scalds; Burns; Perfusion; Laser speckle contrast imaging
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:liu:diva-129497 (URN)10.1016/j.burns.2015.12.005 (DOI)000376507500023 ()26810445 (PubMedID)
Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2019-11-25
2. Accuracy of laser speckle contrast imaging in the assessment of pediatric scald wounds
Open this publication in new window or tab >>Accuracy of laser speckle contrast imaging in the assessment of pediatric scald wounds
2018 (English)In: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 44, no 1, p. 90-98Article in journal (Refereed) Published
Abstract [en]

Background: Changes in microvascular perfusion in scalds in children during the first four days, measured with laser speckle contrast imaging (LSCI), are related to the time to healing and need for surgical intervention. The aim of this study was to determine the accuracy (sensitivity and specificity) of LSCI on different days after injury in the prediction of healing outcome and if the accuracy can be improved by combining an early and a late measurement. Also, the accuracy of LSCI was compared with that of clinical assessment. Methods: Perfusion was measured between 0-24h and between 72-96h using LSCI in 45 children with scalds. On the same occasions, burn surgeons assessed the burns as healing amp;lt; 14days or healing amp;gt; 14days/surgery. Receiver operating characteristic (ROC) curves were constructed for the early and late measurement and for the double measurement (DM) using two different methods. Results: Sensitivity and specificity were 92.3% (95% CI: 64.0-99.8%) and 78.3% (95% CI: 69.985.3%) between 0-24h, 100% (95% CI: 84.6-100%) and 90.4% (95% CI: 83.8-94.9%) between 72-96h, and was 100% (95% CI: 59.0-100%) and 100% (95% CI: 95.1-100%) when combining the two measurements into a modified perfusion trend. Clinical assessment had an accuracy of 67%, Cohens k=0.23. Conclusion: The perfusion in scalds between 72-96h after injury, as measured using LSCI, is highly predictive of healing outcome in scalds when measured. The predictive value can be further improved by incorporating an early perfusion measurement within 24h after injury. (C) 2017 Elsevier Ltd and ISBI. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2018
Keywords
Burn severity; Burn assessment; Scalds; Laser speckle contrast imaging
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:liu:diva-144874 (URN)10.1016/j.burns.2017.06.010 (DOI)000422665600012 ()28797578 (PubMedID)
Available from: 2018-02-09 Created: 2018-02-09 Last updated: 2019-11-25
3. Interobserver reliability of laser speckle contrast imaging in the assessment of burns
Open this publication in new window or tab >>Interobserver reliability of laser speckle contrast imaging in the assessment of burns
2019 (English)In: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 45, no 6, p. 1325-1335Article in journal (Refereed) Published
Abstract [en]

Objectives: Laser speckle contrast imaging (LSCI) is an emerging technique for the assessment of burns in humans and interobserver differences have not been studied. The aim of this study was to compare assessments of perfusion images by different professional groups regarding (i) perfusion values and (ii) burn depth assessment. Methods: Twelve observers without LSCI experience were included. The observers were evenly recruited from three professional groups: plastic surgeons with experience in assessing burns, nurses with experience in treating burns, and junior doctors with limited experience of burns. Ten cases were included. Each case consisted of one digital photo of the burn with a pre-marked region of interest (ROI) and two unmarked perfusion images of the same area. The first and the second perfusion image was from 24h and 72-96h after injury, respectively. The perfusion values from both perfusion images were used to generate a LSCI recommendation based on the perfusion trend (the derivative between the two perfusion values). As a last step, each observer was asked to estimate the burn depth using their clinical experience and all available information. Intraclass correlation (ICC) was calculated between the different professional groups and among all observers. Results: Perfusion values and perfusion trends between all observers had an ICC of 0.96 (95% CI 0.91-0.99). Burn depth assessment by all observers yielded an ICC of 0.53 (95% CI: 0.31-0.80) and an accuracy of 0.53 (weighted kappa). LSCI recommendations generated by all observers had an ICC of 0.95 (95% CI: 0.90-0.99). Conclusion: Observers can reliably identify the same ROI, which results in observer-independent perfusion measurements, irrespective of burn experience. Extensive burn experience did not further improve burn depth assessment. The LSCI recommendation was more accurate in all professional groups. Introducing LSCI measurements would be likely improve early assessment of burns. (C) 2019 Elsevier Ltd and ISBI. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Burn severity; Burn assessment; Scalds; Laser speckle contrast imaging; Interobserver
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:liu:diva-160407 (URN)10.1016/j.burns.2019.01.011 (DOI)000483339500008 ()31230800 (PubMedID)
Available from: 2019-09-23 Created: 2019-09-23 Last updated: 2020-01-03

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