Resilient anatomy and local plasticity of naive and stress haematopoiesis.

The bone marrow adjusts blood cell production to meet physiological demands in response to insults. The spatial organization of normal and stress responses are unknown owing to the lack of methods to visualize most steps of blood production. Here we develop strategies to image multipotent haematopoiesis, erythropoiesis and lymphopoiesis in mice. We combine these with imaging of myelopoiesis1 to define the anatomy of normal and stress haematopoiesis. In the steady state, across the skeleton, single stem cells and multipotent progenitors distribute through the marrow enriched near megakaryocytes. Lineage-committed progenitors are recruited to blood vessels, where they contribute to lineage-specific microanatomical structures composed of progenitors and immature cells, which function as the production sites for each major blood lineage. This overall anatomy is resilient to insults, as it was maintained after haemorrhage, systemic bacterial infection and granulocyte colony-stimulating factor (G-CSF) treatment, and during ageing. Production sites enable haematopoietic plasticity as they differentially and selectively modulate their numbers and output in response to insults. We found that stress responses are variable across the skeleton: the tibia and the sternum respond in opposite ways to G-CSF, and the skull does not increase erythropoiesis after haemorrhage. Our studies enable in situ analyses of haematopoiesis, define the anatomy of normal and stress responses, identify discrete microanatomical production sites that confer plasticity to haematopoiesis, and uncover unprecedented heterogeneity of stress responses across the skeleton.

Anatomical study of the perforator flap based on the acromial branch of the thoraco-acromial artery (abTAA flap): a cadaveric study.

PURPOSE: The aim of this anatomical study was to describe a local perforator flap, for covering shoulder defects, by determining the features of the acromial branch of the thoraco-acromial artery (abTAA), and the supplied cutaneous area. METHODS: Thirteen fresh cadaveric thoraxes were dissected bilaterally. A precise and reproducible protocol was performed. For each abTAA flap cadaveric dissection, the following parameters were measured after arterial injection: distances between the origin of the perforator artery on the abTAA and the sternum, the acromion, the clavicle, diameter of the perforator artery of the abTAA, length of the perforator pedicle course through major pectoralis muscle, and rotation arc. We also calculated the surface of the injected skin paddle. These measurements were related to morphometric parameters evaluated through the distance between sternum and acromion. RESULTS: The mean distances measured from the origin of the perforator artery on the abTAA were 14.25 cm to the sternum, 3.45 cm to the acromion, 5.65 cm to the clavicle. The mean diameter of the abTAA was 1.20 mm ± 0.2. The arc of rotation was 180°, and the length of the perforator pedicle could be extended to 7.46 cm ± 1.15. We observed an colored elliptical cutaneous paddle with a longer radius 18 cm and a small radius 15 cm. CONCLUSIONS: Our results suggest that this type of flap could be useful in clinical practice for reconstruction and covering of the acromial area with a thin cutaneous flap with low sequelae on the donor site.

A cool response-The influence of ambient temperature on capillary refill time.

OBJECTIVE: To describe the effect of low ambient temperature on skin temperature and capillary refill (CR) time in forehead, sternum and finger pulp. METHODS: An observational, nonrandomized experimental study on 15 healthy subjects (6 females) in a cold room (8°C). Outcome measures were skin temperature and quantified CR test after application of a standardized blanching pressure (9 N/cm2 ) using digital photographic polarization spectroscopy to generate CR times. RESULTS: The finger pulp showed marked temperature fall and prolonged CR times (>10 seconds). The CR registrations of the forehead and sternum were more comparable to curves observed in a control material at room temperature, and skin temperature falls were less marked. CR times were not prolonged in forehead measurements. At the sternum, some individuals showed CR times beyond guideline recommendations despite only a marginal reduction in skin temperature. CONCLUSIONS: Low ambient temperature is a strong independent factor for CR time at peripheral sites. Reservation about sternum as a site of measurement is warranted since cold provocation produced prolonged CR times in some individuals. We found that the forehead is the most thermostable of the 3 sites and thus the preferred site to avoid ambient temperature artifact in measuring CR time.

Changes in sternal perfusion following internal mammary artery bypass surgery.

BACKGROUND: Coronary bypass surgery using the internal mammary artery (IMA) is among the most commonly performed procedures in treatment of advanced coronary vessel disease. Further, bilateral harvesting of the IMA is associated with increased rates of sternal wound infections. OBJECTIVE: This study aimed to explore changes in sternal perfusion, following left internal mammary artery (LIMA) harvesting. METHODS: 60 patients were divided equally into intervention- and control cohorts and underwent assessment of oxygen saturation (sO2) and relative blood flow (RBF) by laser doppler flowmetry remission spectroscopy preoperatively, 24 h and 72 h postoperatively. RESULTS: 24 h postoperatively a significant decrease of sO2 and RBF could be detected in LIMA harvest patients. After 72 h this difference disappeared. The side comparison within the groups 24 h postoperatively revealed a reduction of sO2 on the LIMA side within both groups. Regarding the 24 h RBF in side comparison, no significant differences could be detected within the groups. The 72 h side comparison showed an increased RBF for the non-LIMA side within the control group. CONCLUSIONS: The use of the LIMA may lead to significant decreases in local tissue oxygen saturation and RBF. This reduction is mostly distinct within the first 3 days postoperatively and may influence sternal wound infections.

Comparison of peripheral and central capillary refill time in febrile children presenting to a paediatric emergency department and its utility in identifying children with serious bacterial infection.

OBJECTIVE: To determine the agreement between peripheral and central capillary refill time (pCRT/cCRT) and their diagnostic values for detecting serious bacterial infection (SBI) in febrile children attending the paediatric emergency department (ED). DESIGN: Prospective observational study. SETTING: Paediatric ED, Erasmus Medium Care-Sophia Children's hospital, the Netherlands. PATIENTS: 1193 consecutively included, previously healthy, febrile children (1 month-16 years) with both pCRT measurements and cCRT measurements available. SBI diagnosis was based on abnormal radiographic findings and/or positive cultures from normally sterile locations in addition to clinical criteria. MAIN OUTCOME MEASURES: Agreement between pCRT and cCRT (Cohen's κ), overall and stratified for age and body temperature. The diagnostic value of pCRT and cCRT for SBI was assessed with logistic regression. RESULTS: Overall agreement was 0.35 (95% CI 0.27 to 0.43; considered 'fair'). Although not significant, agreement was lower in children aged 1-<5 years (κ: 0.15 (95% CI 0.04 to 0.27)) and decreased with higher body temperatures with κ ranging from 0.55 (95% CI 0.32 to 0.79) for temperature <37.5°C to 0.21 (95% CI 0.07 to 0.34) for temperature >39.5°C. Abnormal pCRT (>2 s) was observed in 153 (12.8%; 95% CI 10.9% to 14.7%) and abnormal cCRT in 55 (4.6%; 95% CI 3.4% to 5.8%) children. The OR of abnormal pCRT (>2 s) for predicting SBI was 1.10 (95% CI 0.65 to 1.84). For abnormal cCRT (>2 s), the OR was 0.43 (95% CI 0.13 to 1.39). CONCLUSIONS: The pCRT and cCRT values showed only fair agreement in a general population of febrile children at the ED, and no significant association with age or body temperature was found. Only a small part of febrile children at risk for serious infections at the ED show abnormal CRT values. Both abnormal pCRT and cCRT (defined as >2 s) performed poorly and were non-significant in this study detecting SBI in a general population of febrile children.

A Review of Differing Techniques of Mammary Artery Harvesting on Sternal Perfusion: Time for a Randomized Study?

The use of internal mammary artery (IMA) grafts for coronary artery bypass may devascularize the sternum. We performed a literature review by searching the PubMed database for studies that assessed sternal perfusion after IMA harvesting. The majority of papers describe various techniques and compared (1) IMA harvest versus no IMA harvest, (2) single versus bilateral, and (3) skeletonized versus pedicled. Evidence is inconclusive as to whether single harvesting causes significant devascularisation and whether this is increased with bilateral harvesting. Sternal ischemia may also be a transient phenomenon. However, skeletonization may preserve perfusion more than pedicled harvesting, particularly in diabetic patients.

Reduced left internal mammary artery blood flow on normal sternal retraction.

The left internal mammary artery is the conduit of choice for bypassing the left anterior descending artery. A 72-year-old man underwent off-pump triple-vessel coronary artery bypass. The left internal mammary artery was harvested with brisk blood flow from the distal artery on completion of harvesting, but normal sternal retraction with a Medtronic OctoBase retractor led to cessation of flow. A vein graft was utilized for the left anterior descending artery, and the internal mammary artery was grafted to the first diagonal branch. Computed tomography-angiography on postoperative day 5 demonstrated no possible cause of the reduced flow on sternal retraction.

Diagnostic value of parasternal pulmonary artery short-axis view for the anomalous origin of the left coronary artery from the pulmonary artery.

OBJECTIVE: To evaluate the diagnostic value of parasternal pulmonary artery (PA) short-axis view for the anomalous origin of left coronary artery (LCA) from the pulmonary artery by echocardiography. METHODS: A total of 13 patients (3 boys) aged from 2 months to 12 years were enrolled. Transthoracic echocardiography, including cross-sectional imaging and color Doppler flow imaging, were performed, and their diagnoses were confirmed by operation. RESULTS: Among the 13 patients, 7 had LCA originated from the left posterior wall of PA, 2 from the posterior wall, and 4 from the right posterior wall. The PA short-axis view could visualize the anomalous origin of the LCA from left posterior or posterior wall of PA clearly. The LCA and aortic wall were overlapping at 3-4 o'clock at PA short-axis view in the patients with LCA originating from the right posterior wall of PA. It was similar with the image of the LCA originating from the aorta. But the blood flow was opposite to that of LCA with normal origin. CONCLUSIONS: The parasternal PA short-axis view is a good view to visualize the anomalous origin of the LCA.

Internal mammary artery harvesting influences antibiotic penetration into presternal tissue.

BACKGROUND: Internal mammary artery (IMA) harvesting for coronary artery bypass grafting (CABG) influences tissue perfusion and represents a risk factor for deep sternal wound infection (DSWI). Cephalosporins are routinely administered for prophylaxis during cardiac operations to decrease perioperative wound infections. We hypothesized that mammary artery preparation impairs antibiotic penetration into presternal tissue during CABG. METHODS: Eight patients undergoing skeletonized left mammary artery harvesting for CABG were included. Standard antibiotic prophylaxis was administered: 4 g of cefazolin before skin incision and an additional 2 g during skin closure. Concentrations of cefazolin were measured in subcutaneous tissue on the presternal right and left sides (surgically affected) after sternotomy and additionally in subcutaneous tissue on the thigh (surgically unaffected) by microdialysis over a 10-hour period. RESULTS: Mean peak tissue concentration and the area under the curve (AUC) on the left sternal side were significantly reduced compared with the right side and compared with the thigh (mean peak concentration, 13.1±5.8 versus 24.1±4.7 and 27.8±9.7 µg/mL; p=0.005 and p=0.013; AUC 74.2±31.0 versus 110.4±25.0 and 140.3±46.3 µg×hours per milliliter; p=0.004 and p=0.002). Mean subcutaneous concentrations of cefazolin on the left sternal side exceeded the minimal inhibitory concentration (MIC90) of Staphylococcus epidermidis of 4 µg/mL in only 5 of 8 (37.5%) patients after 5 hours. CONCLUSIONS: IMA harvesting significantly impairs local antibiotic penetration during CABG. Common antibiotic dosing schemas should be reevaluated in this cardiac surgical setting.

The agreement of fingertip and sternum capillary refill time in children.

OBJECTIVES: To determine the agreement of fingertip and sternum capillary refill time (CRT) in children. DESIGN: Prospective, method-comparison study. SETTING: Single children's emergency department, UK PARTICIPANTS: 92 children aged 0-12 years, with clinical observations within normal ranges for their age, no relevant medical history and presenting to hospital with a minor illness or injury. MAIN OUTCOME MEASURES: Agreement between fingertip and sternum CRT measurements. RESULTS: Fingertip CRT ranged from 0.05 to 2.78 s with a mean of 1.08±0.44 and sternum CRT ranged from 0.85 to 2.38 s with a mean of 1.5±0.33. There was a significant difference between fingertip and sternum CRT (t=-9.2, df=91, p=<0.001) and a weak association between the two measurements (r=0.18, p=0.9). A Bland Altman comparison showed the mean difference between fingertip and sternum CRT was -0.49±0.51 with an upper and lower limit of agreement ranging from -1.5 (95% CI -1.69 to -1.32) to 0.53 (95% CI 0.34 to 0.71). CONCLUSIONS: Measurements of CRT taken at the fingertip and sternum are not comparable. Fingertip CRT was faster than sternum CRT. Normal CRT is 2-3 s. The current study questions the usefulness of CRT in the assessment of circulation in children.

Reduction of sternal wound infections in diabetic patients undergoing off-pump coronary artery bypass surgery and using modified pedicle bilateral internal thoracic artery harvest technique.

OBJECTIVE: We compared sternal wound infections between diabetic patients undergoing off-pump coronary artery bypass surgery using bilateral internal thoracic artery grafting or single internal thoracic artery grafting and nondiabetic patients receiving bilateral internal thoracic artery or single internal thoracic artery grafting using a modified pedicled harvest technique of internal thoracic artery. METHODS: This retrospective study was conducted to analyze the data from 3072 patients who underwent primary coronary artery bypass surgery using an off-pump technique from August 2004 to October 2010. Of the 1211 diabetic patients, 181 received bilateral internal thoracic artery grafts (group 1) and 1030 received single internal thoracic artery grafts (group 2). Of the 1861 nondiabetic patients, 161 received bilateral internal thoracic artery grafts (group 3) and 1700 received single internal thoracic artery grafts (group 4). The incidence of postoperative sternal wound infections in diabetic patients who received bilateral internal thoracic artery grafting was compared with the incidence in other groups (group 2, 3, and 4). A modified technique of pedicled harvesting of the internal thoracic artery was done in patients receiving bilateral internal thoracic artery grafting, and a standard pedicled harvest was used in patients receiving single internal thoracic artery grafts. RESULTS: No significant differences were present in the preoperative variables among the groups. The observed rate of superficial sternal wound infections in groups 1, 2, 3, and 4 was 1.1% (2 patients), 1.65% (17 patients), 1.86% (3 patients), and 1.65% (28 patients), respectively (P=.9941). Deep sternal infections were observed in 1 (0.55%), 5 (0.48%), 1 (0.62%), and 14 patients (0.82%) in groups 1 through 4, respectively (P=.8380). Multivariate analysis showed that bilateral internal thoracic artery harvesting (P=.889), diabetes mellitus (P=.96), and patient age were not predictors of sternal wound infection. CONCLUSIONS: The results of the present study show that there is no increase in the incidence of sternal wound infections in diabetic patients undergoing coronary artery bypass surgery with bilateral internal thoracic artery grafting by using a modified pedicle bilateral internal thoracic artery harvesting technique with sparing of the communicating bifurcation of internal thoracic artery to the chest wall and preservation of pericardiacophrenic artery branch.

Sternal neoangiogenesis following internal mammary artery devascularization: an experimental model.

AIM: The use of bilateral internal thoracic arteries (BIMA) for coronary artery revascularization is associated with better long-term survival and longer freedom from reoperation. Concerns of deep sternal wound infections and mediastinitis have constantly emerged with the utilization of BIMA grafts on a routine basis, especially in diabetic patients. METHODS: We performed a quantitative evaluation of sternal bone healing and angiogenesis after left (LIMA) or bilateral internal mammary artery (BIMA) ligation two and four weeks after sternotomy in normal and diabetic Sprague-Dawley rats. RESULTS: The BIMA group showed a significant increase in neoangiogenesis two weeks after surgery compared to LIMA and control groups (control: 38.3 ± 5.1 vessels/mm², LIMA: 31.4 ± 3.6 vessels/mm², BIMA: 81.6 ± 7.7 vessels/mm²; P=0.047 and P=0.04, respectively). Four weeks after the procedure, bilateral devascularization was associated with lower microvessel formation when compared to LIMA or control groups (control: 50.4 ± 5.2 vessels/mm², LIMA: 64.6 ± 4.9 vessels/mm²; BIMA: 31.5 ± 4.4 vessels/mm²; P=0.006 and P=0.02, respectively). Diabetic animals showed similar results with lower four weeks microvessel formation. However, there were no significant differences when animals with induced diabetes were compared to the normal euglycemic groups for each procedure performed. CONCLUSION: BIMA ligation promotes an early increase in neoangiogenesis. Progressive sternal consolidation is associated with a significant lower level of capillaries and arterioles in the BIMA group four weeks after ligation. Diabetes did not influence the extent of neoangiogenesis between groups with similar procedures. More important clinical determinants could explain the increase incidence of sternal infection in this specific population.

Decreasing sternum microcirculation after harvesting the internal thoracic artery.

OBJECTIVE: The effect of harvesting the internal thoracic artery (ITA) on blood supply to the sternum is not completely understood. Using a novel laser Doppler flow meter, we evaluated changes in sternum microcirculation prior to and after ITA harvesting. METHODS: Forty-six patients (37 males, 69.4 ± 7.9 years) scheduled for coronary artery bypass grafting were enrolled into the study and divided into skeletonized (n = 23) and pedicled (n = 23) groups of patients with a left ITA. All right ITA were harvested using the skeletonized method. Sternal blood flow was measured presternally and retrosternally in the upper, middle, and lower sternal parts with a novel laser Doppler flow meter that measures blood flow at 1-mm depth using a 780-nm laser. Following median sternotomy, blood flow was measured before and after ITA harvesting. RESULTS: In all patients (46 left and 16 right ITA cases), the middle part of the retrosternal microcirculation deteriorated (middle: pre- 2.71 ± 1.49, post- 2.43 ± 1.01 ml min(-1)100 g(-1); p < 0.05), while blood flow of other parts did not change. In patients with left ITA divided into skeletonized and pedicled groups, although middle retrosternal blood flow decreased after harvesting in both groups, there was no difference in deterioration between the groups. In patients with right ITA, the middle and lower retrosternal blood flow also deteriorated. CONCLUSIONS: The degree of sternal microcirculation damage after ITA harvesting is not different between skeletonized and pedicled group patients, suggesting that skeletonization is not advantageous for maintaining sternal microcirculation.

A new practical alternative for the control of sternal bleeding during cardiac surgery: Ankaferd Blood Stopper.

The control of sternal bleeding during cardiac surgery can sometimes be a challenging and time-consuming problem for surgeons. Several alternatives for the control of sternal bleeding are on the market. Bone wax is a well-known alternative used by many cardiac surgeons for the control of bleeding. It is effective and cheap; however, it inhibits ossification of the sternum and can cause infections and sternal wound healing problems after cardiac surgery. Consequently, control of sternal bleeding without the use of bone wax requires meticulous preparation. Ankaferd Blood Stopper (ABS) (Ankaferd Saglik Ürünleri, Istanbul, Turkey) is a unique folkloric medicinal plant extract that has been used in Turkish traditional medicine as a hemostatic agent. We present a practical alternative technique for the control of sternal bleeding during cardiac surgery with the use of ABS.

Sternal resection for sarcoma, recurrent breast cancer, and radiation-induced necrosis.

BACKGROUND: The purpose of this study was to investigate the long-term outcome and technical feasibility of sternal resection. METHODS: We performed a 25-year retrospective study of 68 patients who underwent a sternectomy for sarcoma, recurrent breast cancer (BC) or radiation-induced necrosis between 1981 and 2006 in two tertiary referral centres (Erasmus Medical Center/Daniel den Hoed Cancer Center and Netherlands Cancer Center/Antoni van Leeuwenhoek Hospital, Netherlands). Patients were treated with curative intent and followed until May 2009. Medical records were reviewed for patient characteristics, indications for surgery, surgical technique, postoperative complications, and survival. RESULTS: Sternal resection was performed in 43 sarcoma patients, 17 recurrent BC and 8 patients with radiation-induced necrosis with additional rib resection in the majority of patients and with clavicle resection in 13% of patients. Additional scapula, lung, breast or axilla resection, or both, was performed in 10%. Two patients died postoperatively (3%). Mild complications occurred in 24%, and severe complications (namely, pulmonary complications and reinterventions) in 16% of patients. Radical resection was achieved in 80% and 53% of sarcoma and recurrent BC patients, respectively. Five-year overall survival was 64% and 40% in sarcoma and recurrent BC patients, respectively, with 5-year disease-free survivals of 52% and 15%, respectively. CONCLUSIONS: Sarcomas, recurrent BC, and radiation-induced necrosis can be successfully managed by sternal resection and reconstruction with curative intent. Low mortality and acceptable morbidity rates justify this operation in a palliative setting as well. Disease-free survival is poor among recurrent BC patients.

Arteriovenous loops in microsurgical free tissue transfer in reconstruction of central sternal defects.

OBJECTIVE: In some patients with chest wall defects, free tissue transfer is indicated. Complications arise if multiple operations have left the trunk devoid of recipient vessels. In such patients, an arteriovenous loop between the cephalic vein and the thoracoacromial artery can be used. METHODS: A review of all our patients who underwent chest wall reconstruction with a cephalic vein-thoracoacromial artery loop between 2000 and 2009 was performed (n = 29, 19 women and 10 men). The mean age was 64.9 years. Underlying causes were sternal osteomyelitis (n = 20), tumor (n = 4), and osteoradionecrosis (n = 5). All patients were in American Society of Anesthesiologists classes III and IV. Flap selection, intraoperative and postoperative complications, operative time, time of ventilatory support, mean hospital stay, and midterm survival were recorded. RESULTS: Twenty-five patients received a tensor fascia lata flap, 2 a vertical rectus myocutaneuos flap, and 2 a deep inferior epigastric perforator flap. Mean duration of surgery was 6.8 hours (4.7-10.5 hours). Two transplanted tissue flaps died and/or had to be removed and 4 were revised successfully. Seven patients had wound complications such as infection or prolonged wound healing. Mean time for ventilator support was 93.6 hours (4-463 hours). The median intensive care unit time was 11 days and the overall hospital stay 27.4 days (11-102 days). One-year survival in the whole group was 69.8%. CONCLUSIONS: The concept of arteriovenous loops allows creation of neovessels at the recipient site and has proven to be a superb tool to facilitate free tissue transfer or to provide an exit strategy in situations with unexpected vascular problems at the recipient site.