An interventional study of Abdominal Wall Closure Force (N). in Ventral Hernia and Abdominal Wall Defect, sponsored by University College, London. Status unknown at 1 site in United Kingdom. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2018-05-31.
Sponsored by University College, London · Not applicable, Interventional, and Basic science
Background: A detailed study of the biomechanical changes before and after abdominal wall reconstruction (AWR) has not been performed. Changes in abdominal wall tension and intra-abdominal pressure have physiological consequences on respiratory and cardiology function. AWR surgeons currently do not know if they are applying too much tension when re-aligning the abdominal wall muscles during AWR. Too much tension is likely to cause respiratory and cardiac post-operative complications. The investigators propose to study the perioperative changes in abdominal biomechanics and cardiorespiratory physiology after AWR. In addition, investigators will also analyze the pre-operative patient CT scan to see if there any CT predictors of post-operative cardiorespiratory complications and hernia recurrence. The researchers hypothesize that there is a threshold value or force at which ventral hernias are repaired 'too tight' subjecting the patient to the increased risk of recurrence and cardiorespiratory complications.
Method: An in depth biomechanical and physiological study of 18-22 participants with midline ventral hernias will be carried out. Ventral hernias at least 5cm in width and only those in which primary fascial closure have been achieved will be included. Any operative technique used to achieve primary fascial closure will be included. Biomechanical and physiological measurements will be taken at five separate stages during the course of the patients' abdominal wall reconstruction. The final lung function tests, taken six weeks post op, will be compared to the patients' pre-operative tests. Meticulous attention will be paid to the study protocol making sure that in each patient the measurements are all taken at the same time and under the same conditions.
Discussion: This full biomechanical and physiological work up will enable AWR surgeons to assess when an AWR patient is subjected to too much biomechanical and physiological stress. The abdominal wall tension and strain will be measured to see if this predicts post complications and hernia recurrence.
Exclusion Criteria:
Main inclusion criteria: * Patients with midline hernia defects. * Patients with either a maximal ventral hernia axial width of greater than 5cm or a loss of domain of greater then 20%. * Patients aged ≥ 18 years old. * Midline hernias closed in the midline with primary fascial closure with or without mesh augmentation. * Midline ventral hernias of VHWG grade 2 or 3.
Procedure: Abdominal Wall Closure Force (N).
This measurement will be recorded for both the right and left anterior rectus sheath. We will measure this force at three anatomical points 1) at the level of the umbilicus and 2) at the halfway point between the pubic symphysis and the xiphisternum and 3) at the point of maximal hernia defect width.
Dynamic Lung Compliance (measured in ml/cmH2O)
The primary outcome is the difference in Lung Compliance between stages 3 and 4 of the peri-operative protocol. i.e. we will measure the change in dynamic lung compliance before (after adhesiolysis) and after abdominal wall closure. We will measure this with a standard operative ventilator. Every patient will have a definitive airway (ET tube) fitted.
Time frame: Day 1. Both measurements will be taken on the participants first day of the study. (Study enrollment will take place on the day of the participants operation.
Perioperative changes in Total Lung Capacity (Litres)
Total Lung Capacity (TLC) (Litres). TLC will be measured using spirometry before and after the patients AWR operation.
Time frame: TLC will be measured on Day 1 and at 6 weeks, 12 months and 3 years after the patients operation.
Perioperative changes in Force Expiratory Volume (Litres)
Force Expiratory Volume over 1 second, FEV1 (Litres). FEV1 will be measured using spirometry before and after the patients AWR operation.
Time frame: FEV1 will be measured on Day 1 and at 6 weeks, 12 months and 3 years after the patients operation.
Perioperative changes in Tidal Volume (Litres)
Tidal Volume, VT (Litres). VT will be measured using spirometry before and after the patients AWR operation.
Time frame: VT will be measured on Day 1 and at 6 weeks, 12 months and 3 years after the patients operation.
Perioperative changes in Residual Volume (Litres)
Residual Volume, RV (Litres). RV will be measured using spirometry before and after the patients AWR operation.
Time frame: RV will be measured on Day 1 and at 6 weeks, 12 months and 3 years after the patients operation.
Perioperative changes in Peak Expiratory Flow (Litres/min)
Peak Expiratory Flow, PEF (Litres/min). PEF will be measured using spirometry before and after the patients AWR operation.
Time frame: PEF will be measured on Day 1 and at 6 weeks, 12 months and 3 years after the patients operation.
Perioperative changes in Dynamic Lung Compliance (ml/cmH2O)
Dynamic Lung Compliance, LC (ml/cmH2O). LC will be measured using spirometry before and after the patients AWR operation.
Time frame: LC will be measured on Day 1 and at 6 weeks, 12 months and 3 years after the patients operation.
Abdominal wall closure force before abdominal wall closure (Newtons)
Measured in Newtons (N) with a Mecmesin Newton meter. After adhesiolysis (stage 3) and before abdominal wall closure.
Time frame: Day 1. These abdominal wall closure measurements will be taken during the participants operation on the first day of the study. i.e. after enrollment, which will take place on the day of their operation.
Abdominal wall strain index (no units) (this is a strain index, change in transverse length (cm) / original transverse length of abdominal wall (cm))
Calculated using the pre-operative CT or MRI and by recording the hernia defect width intra-operatively.
Time frame: Day 1. Defect width readings taken during the abdominal wall reconstruction operation
Ventral hernia recurrence
Rate of ventral hernia recurrence at 1 year, defined by clinical examination and supplemented by cross-sectional imaging where there is diagnostic uncertainty. Recurrence will be defined using the European classification for ventral hernia recurrence.
Time frame: At 1 year after the patients operation.
Perioperative change in Intra-abdominal pressure (IAP) (mmHg)
Intra-abdominal pressure IAP (mmHg) will be measured using a transducer probe inserted into the bevel of a urinary catheter. The bladder will be inflated with 50ml of normal saline solution, the catheter will be clamped off distal to the position of the transducer/bevel. The bag of normal saline will be lowered to the level of the bladder when the IAP readings are taken. IAP reading will be taken at stages 2, 3 and 4 of our protocol (ie after induction of anaesthetic, after adhesiolysis, and after abdominal wall closure).
Time frame: Day 1. Readings taken during the abdominal wall reconstruction operation
Perioperative change in cardiac output (CO) (L/min)
Each participant will be fitted with an oesophageal doppler probe during their operation. This will measure the cardiac output. CO readings will be taken at stages 2, 3 and 4 of our protocol (ie after induction of anaesthetic, after adhesiolysis, and after abdominal wall closure).
Time frame: Day 1. Readings taken during the abdominal wall reconstruction operation
Perioperative change in stroke volume (SV) (L)
Each participant will be fitted with an oesophageal doppler probe during their operation. This will measure the cardiac stroke volume. SV readings will be taken at stages 2, 3 and 4 of our protocol (ie after induction of anaesthetic, after adhesiolysis, and after abdominal wall closure).
Time frame: Day 1. Readings taken during the abdominal wall reconstruction operation
Perioperative change in positive-end expiratory pressure (PEEP) (cm/H2O)
Positive-end expiratory pressure (PEEP) (cm/H2O) will be measured using the operative ventilator during the patient's operation. PEEP readings will be taken at stages 2, 3 and 4 of our protocol (ie after induction of anaesthetic, after adhesiolysis, and after abdominal wall closure).
Time frame: Day 1. Readings taken during the abdominal wall reconstruction operation
Perioperative change in fraction of inspired oxygen (fraction or as a per cent)
Fraction of inspired oxygen (FiO2) will be measured using the operative ventilator during the patient's operation. FiO2 readings will be taken at stages 2, 3 and 4 of our protocol (ie after induction of anaesthetic, after adhesiolysis, and after abdominal wall closure).
Time frame: Day 1. Readings taken during the abdominal wall reconstruction operation
Perioperative physiological changes in partial pressure of oxygen (pO2) (kPA)
Blood partial pressure of oxygen (pO2) (kPA) will be measured from arterial gas samples that will be taken from the patients arterial line during the operation. pO2 readings will be taken at stages 2, 3 and 4 of our protocol (ie after induction of anaesthetic, after adhesiolysis, and after abdominal wall closure).
Time frame: Day 1. Readings taken during the abdominal wall reconstruction operation
Rates of (a) intra-operative, (b) early post-operative (within 30 days of operation) and (c) late post-operative complications.
Early and late complications will be grouped into local wound complications (e.g. wound infection, seroma etc) and systemic complications (e.g. pneumonia, myocardial infarction etc). We will follow the Clavien-Dindo classification scheme.
Time frame: Up to 3 years after the patients operation.
Ventral hernia recurrence
Rate of ventral hernia recurrence at 3 years, defined by clinical examination and supplemented by cross-sectional imaging where there is diagnostic uncertainty. Recurrence will be defined using the European classification for ventral hernia recurrence.
Time frame: At 3 year after the patients operation.
Plan to share: No — Designated members of the research team will be responsible for data entry at different steps of the patient pathway. All researchers will be responsible for the accuracy of the documentation and must ensure that all entries can be verified by the source data. An explanation will be given for all missing data. All the study documents and proformas containing the participant data will be kept on site in the General Surgery department at our hospital. At no point, will these documents be removed from the department. Study data will be pseudo-anonymised for data analysis. The file containing the pseudo-anonymised data will be password protected. Only the pseudo-anonymised data will leave the hospital department, it will be transferred using the secure UCLH.nhs.uk and NHS.net email systems. Only the primary researcher, SGP, will have access to the pseudo-anonymised data outside our hospital department, where the password protected data file will be keep on his secure personal laptop.
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University College, London