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| 2. |
- Lindstedt Ingemansson, Sandra, et al.
(författare)
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A compare between myocardial topical negative pressure levels of-25 mmHg and-50 mmHg in a porcine model
- 2008
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 8:14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Topical negative pressure (TNP), widely used in wound therapy, is known to stimulate wound edge blood flow, granulation tissue formation, angiogenesis, and revascularization. We have previously shown that application of a TNP of -50 mmHg to the myocardium significantly increases microvascular blood flow in the underlying tissue. We have also shown that a myocardial TNP levels between -75 mmHg and -150 mmHg do not induce microvascular blood flow changes in the underlying myocardium. The present study was designed to elucidate the difference between -25 mmHg and -50 mmHg TNP on microvascular flow in normal and ischemic myocardium. Methods: Six pigs underwent median sternotomy. The microvascular blood flow in the myocardium was recorded before and after the application of TNP using laser Doppler flowmetry. Analyses were performed before left anterior descending artery (LAD) occlusion (normal myocardium), and after 20 minutes of LAD occlusion (ischemic myocardium). Results: A TNP of -25 mmHg significantly increased microvascular blood flow in both normal (from 263.3 +/- 62.8 PU before, to 380.0 +/- 80.6 PU after TNP application, *p = 0.03) and ischemic myocardium (from 58.8 +/- 17.7 PU before, to 85.8 +/- 20.9 PU after TNP application, *p = 0.04). A TNP of -50 mmHg also significantly increased microvascular blood flow in both normal (from 174.2 +/- 20.8 PU before, to 240.0 +/- 34.4 PU after TNP application, *p = 0.02) and ischemic myocardium (from 44.5 +/- 14.0 PU before, to 106.2 +/- 26.6 PU after TNP application, **p = 0.01). Conclusion: Topical negative pressure of -25 mmHg and -50 mmHg both induced a significant increase in microvascular blood flow in normal and in ischemic myocardium. The increase in microvascular blood flow was larger when using -25 mmHg on normal myocardium, and was larger when using -50 mmHg on ischemic myocardium; however these differences were not statistically significant.
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| 3. |
- Malmsjö, Malin, et al.
(författare)
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Preventing heart injury during negative pressure wound therapy in cardiac surgery: assessment using real-time magnetic resonance imaging.
- 2009
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Ingår i: The Journal of thoracic and cardiovascular surgery. - : Elsevier BV. - 1097-685X .- 0022-5223. ; 138:3, s. 712-717
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Heart rupture is a devastating complication to negative pressure wound therapy in cardiac surgery. Also, reduced cardiac output during negative pressure wound therapy has been reported. The present study aimed to examine the effects of negative pressure wound therapy on the position of the heart in relation to the thoracic wall using magnetic resonance imaging in a porcine sternotomy wound model. METHODS: Six pigs had median sternotomy followed by negative pressure wound therapy at -75, -125, and -175 mm Hg. Real-time magnetic resonance imaging movies (10 images/s) were acquired in a midventricular transverse plane or a midsagittal plane during the application of negative pressure wound therapy. RESULTS: Similar finding were observed at all different negative pressures studied. Negative pressure wound therapy caused the heart to be displaced toward the thoracic wall, and in some cases, the right ventricular free wall bulged into the space between the sternal edges, and the sharp edges of the sternum jutted into and deformed the anterior surface of the right ventricular free wall. These events were not affected by the interposition of 4 layers of paraffin gauze dressing but were hindered by the placement of a rigid barrier between the anterior portion of the heart and the inside of the thoracic wall. CONCLUSION: The results show altered position of the heart in relation to the sternum during negative pressure wound therapy. This may explain 2 potentially hazardous events associated with negative pressure wound therapy, namely, risk for heart rupture and reduced cardiac output. Inserting a rigid barrier over the heart may be a protective measure that is clinically practicable.
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| 4. |
- Mokhtari, Arash, et al.
(författare)
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Haemodynamic effects of -75 mmHg negative pressure therapy in a porcine sternotomy wound model.
- 2009
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Ingår i: International Wound Journal. - 1742-481X. ; 6:1, s. 48-54
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown -125 mmHg to be the optimal negative pressure for creating an environment that promotes wound healing, and this has therefore been adopted as a standard pressure for patients with deep sternal wound infection. However, it has not yet been clearly shown that -125 mmHg is the optimal pressure from a haemodynamic point of view. Furthermore, there have been reports of cardiac rupture during -125 mmHg negative pressure therapy. We therefore studied the effects of a lower pressure: -75 mmHg. Twelve pigs were used. After median sternotomy, sealed negative pressure therapy of -75 mmHg was applied. Baseline measurements were made and continuous recording of the cardiac output, end-tidal CO(2) production, mean arterial pressure, mean pulmonary pressure (pulmonary artery pressure), systemic vascular resistance, pulmonary vascular resistance, left atrial pressure and central venous pressure was started. Six pigs served as controls. No statistically significant difference was observed in any of the haemodynamic parameters studied, compared with the controls. The present study shows that, with a suitable foam application technique, -75 mmHg can be applied without compromising the central haemodynamics.
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| 5. |
- Mokhtari, Arash, et al.
(författare)
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Sternal stability at different negative pressures during vacuum-assisted closure therapy
- 2006
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Ingår i: Annals of Thoracic Surgery. - : Elsevier BV. - 1552-6259 .- 0003-4975. ; 82:3, s. 1063-1067
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Tidskriftsartikel (refereegranskat)abstract
- Background. Vacuum-assisted closure (VAC) is a widely used therapy in patients with poststernotomy mediastinitis. The aim of this study was to evaluate sternal stability during VAC application at seven negative pressures (-50 to -200 mm Hg) in a porcine wound model. Methods. Six pigs underwent median sternotomy and 2 steel wires were fixed at each sternal side and connected to a traction device. The device was connected to a force transducer linked to a force recorder. VAC therapy was applied to the wound. At each negative pressure, the length and width of the wound were measured before and after traction was started. Traction was increased stepwise up to 400 N. Results. The diastasis induced by a certain lateral force was similar in wounds treated with -75, -125, and -175 mm Hg. At -75 mm Hg, a significant improvement (p < 0.01) in sternal stability was seen compared with the open-chest setting. This was not further improved at -125 or -175 mm Hg. High negative pressures (-150 to -200 mm Hg) in combination with a high lateral force (> 200 N) increased the risk of separation of the foam from the wound edges, with air leakage or organ rupture as a result. Conclusions. Our results suggest that low negative pressures (-50 to -100 mm Hg) stabilize the sternum as efficiently as high negative pressures (-150 to -200 mm Hg). Low negative pressures (-50 to -100 mm Hg) were more beneficial, however, because no air leakage or organ rupture was observed at these pressures.
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| 6. |
- Mokhtari, Arash, et al.
(författare)
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The cost of vacuum-assisted closure therapy in treatment of deep sternal wound infection.
- 2008
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 42:1, s. 85-89
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. Surgical sites infections are very expensive and the total costs for coronary artery bypass grafting (CABG) surgery followed by deep sternal wound infection (DSWI) with conventional therapy are estimated to be 2.8 times that for normal, CABG surgery. Promising results have been reported with vacuum-assisted closure (VAC) therapy in patients with DSWI. This study presents the cost of VAC therapy in patients with DSWI after CABG surgery. Design. Thirty-eight CABG patients with DSWI, between 2001 and 2005, were treated with VAC therapy. The cost of surgery, intensive care, ward care, laboratory tests and other costs were analyzed. Results. No three-month mortality or recurrent infection was observed. The average cost of CABG procedure and treatment of DSWI was 2.5 times higher than the mean cost of CABG alone. No significant correlations were found between the preoperative EuroSCORE and the cost of DSWI therapy. Conclusions. VAC therapy for patients who underwent CABG surgery followed by DSWI seems to be cost effective, and has low mortality rate.
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| 7. |
- Mokhtari, Arash
(författare)
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Vacuum-Assisted Closure Therapy after Cardiac Surgery. Sternal Stability, Cost of Care, Learning Curve and Hemodynamic Outcome
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Deep sternal wound infection (DSWI) following cardiothoracic surgery is a rare but potentially life-threatening complication with high morbidity and mortality. DSWI is associated with a significant increase in the length of hospital stay and the cost of hospitalization. The socioeconomic impact of DSWI is considerable. Conventional treatment includes reexploration, surgical debridement, mediastinal antibiotic irrigation-suction, primary or delayed sternal closure, and reconstructive procedures with vascularized tissue flaps. Despite these efforts, patients with DSWI have poor long-term outcome following conventional treatment. Vacuum-assisted closure (VAC) therapy is a new modality for the treatment of problematic chest wound healing. This technique can be performed with less surgical trauma and has been adopted as the standard treatment for DSWI because of its excellent clinical outcome. However, many questions remain concerning VAC therapy, such as the optimal subatmospheric pressure, cost-effectiveness, learning curve effects, survival and changes in hemodynamics. The aims of this work were: (1) to evaluate sternal stability at different negative pressures during VAC therapy; (2) to investigate whether high negative pressures increase the rate of organ rupture (e.g. heart and lungs); (3) to calculate the cost of VAC treatment in patients with DSWI after cardiac surgery; (4) to ascertain whether there is any correlation between the preoperative EuroSCORE and the cost of DSWI therapy; (5) to identify possible effects of the learning curve on survival during the introduction of VAC therapy in patients with DSWI and predictors of late mortality; and finally (6) to investigate changes in the hemodynamics during the application of negative pressure therapy. We found that low negative pressures (–50 to –100 mmHg) stabilize the sternum just as efficiently as high negative pressures (–150 to –200 mmHg). No failure of the foam dressings or organ ruptures were seen following the application of low negative pressures in combination with high lateral forces (above 200 N). VAC therapy in patients with DSWI following cardiac surgery seems to be cost-effective and no correlations were found between the preoperative EuroSCORE and the cost of DSWI therapy after CABG surgery. VAC therapy is thus an excellent adjunct for wound healing in DSWI without significant learning curve effects on early or late mortality. Late diagnosis and prolonged wound therapy were identified as predictors of late mortality. With a suitable foam application technique, a pressure of –75 mmHg can be applied without compromising the central hemodynamics.
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| 8. |
- Mokhtari, Arash X, et al.
(författare)
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Determinants of increasing pulse pressure during 23 years' follow-up as a marker of arterial stiffness and vascular ageing.
- 2008
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Ingår i: Blood Pressure. - : Informa UK Limited. - 0803-7051 .- 1651-1999. ; 17:5-6, s. 291-297
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate clinical characteristics of increased brachial pulse pressure (PP) during long-term follow-up (23 years) as a marker of arterial stiffness in 9704 healthy subjects. The association of baseline variables with an increasing PP burden during the study period was analysed by univariate analysis. In addition, the association between different biological variables at baseline and increasing PP at follow-up, as well as the cross-sectional association with PP at follow-up, were examined by multiple regression analysis. The prospective analysis showed in men that the following baseline variables predicted (p<0.05) increased PP at follow-up: age, fasting glucose, triglycerides, heart rate, smoking, family history of hypertension and cholesterol. Among women, the same predictors were established (p<0.05), except for smoking and triglycerides, but in addition body mass index (BMI). The cross-sectional analysis obtained at the last survey, showed that the following variables (p<0.05) were associated with increased PP in men: fasting glucose, age, BMI, cholesterol and family history of hypertension. In females, similar findings were noted (p<0.05), but in addition there was a negative correlation with smoking. In conclusion, several well-known cardiovascular risk factors, such as glucose, BMI, heart rate, family history of hypertension and cholesterol in particular, are long-term predictors of increased PP in both genders.
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| 9. |
- Petzina, Rainer, et al.
(författare)
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Effect of vacuum-assisted closure on blood flow in the peristernal thoracic wall after internal mammary artery harvesting.
- 2006
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Ingår i: European Journal of Cardio-Thoracic Surgery. - : Oxford University Press (OUP). - 1010-7940. ; 30:1, s. 85-89
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Vacuum-assisted closure (VAC) is a recently introduced method for the treatment of poststernotomy mediastinitis. The aim was to examine the effects of VAC negative pressure on peristernal soft tissue, blood flow after internal mammary artery harvesting. Methods: Microvascular blood flow was measured using laser Doppler velocimetry in a porcine sternotomy wound model. The effect of VAC negative pressure on blood flow to the wound edge was investigated on the right side, where the internal mammary artery was intact, and on the left side, where the internal mammary artery had been removed. Results: Before removal of the left internal mammary artery, the blood flow was similar in the right and left peristernal wound edges, 2.5 cm from the edge (27 +/- 4 perfusion units (PU) on the right side and 32 +/- 3 PU on the left side, in muscle tissue). When the left internal mammary artery was surgically removed, the blood flow on the left side decreased (19 3 PU, in muscle tissue), while the skin blood flow was not affected. VAC negative pressure induced an immediate increase in wound edge blood flow both on the right side (43 +/- 9 PU, in muscle tissue at -75 mmHg), where the internal mammary artery was intact, and on the left side, where the internal mammary artery had been removed (49 11 PU, in muscle tissue at -75 mmHg). The increase in blood flow was similar on both sides at -75 mmHg and at -125 mmHg. Conclusions: The peristernal wound edge microvascular blood flow is decreased when the left internal mammary artery is removed. VAC therapy stimulates blood flow in the peristernal thoracic wall after internal mammary artery harvesting. (c) 2006 Elsevier B.V. All rights reserved.
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| 10. |
- Sjögren, Johan, et al.
(författare)
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Vacuum-assisted closure therapy for deep sternal wound infections: the impact of learning curve on survival and predictors for late mortality.
- 2008
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Ingår i: International Wound Journal. - 1742-481X. ; 5:2, s. 216-223
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the possible learning curve effects on survival during the introduction of vacuum-assisted closure (VAC) therapy in patients with deep sternal wound infection (DSWI). Furthermore, predictors of late mortality were analysed and causes of late death were examined. Fifty-three patients (early Group, n = 26, January 1999 to July 2001 versus late group, n = 27, August 2001 to March 2003) were all treated with VAC for DSWI. A follow-up was carried out in September 2006. Multivariate analyses were used to evaluate the predictors of late mortality. The 90-day mortality was 0% in both groups. The survival rates at 5 years were 69.2 +/- 9.1% (early group) versus 58.5 +/- 11.7% (late group), P = ns (non significant). The time interval from cardiac surgery to diagnosis of DSWI and prolonged VAC therapy were identified as independent predictors of late mortality. Our concept for VAC therapy in DSWI seems to be readily introduced in clinical practice. There was no difference in survival between our initial cases and later cases. Late diagnosis and prolonged wound therapy were identified as predictors for late mortality.
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