Modifications of Surgical Suction Tip Geometry for Flow Optimisation: Influence on Suction-Induced Noise Pollution.

INTRODUCTION: Suction devices for clearing the surgical field are among the most commonly used tools of every surgeon because a better view of the surgical field is essential. Forced suction may produce disturbingly loud noise, which acts as a nonnegligible stressor. Especially, in emergency situations with heavy bleeding, this loud noise has been described as an impeding factor in the medical decision-making process. In addition, there are reports of inner ear damage in patients due to suction noises during operations in the head area. These problems have not been solved yet. The purpose of this study was to analyse flow-dependent suction noise effects of different surgical suction tips. Furthermore, we developed design improvements to these devices. METHODS: We compared five different geometries of suction tips using an in vitro standardised setup. Two commercially available standard suction tips were compared to three adapted new devices regarding their flow-dependent (10-2000 mL/min) noise emission (dB, weighting filter (A), distance 10 cm) and acoustic quality of resulting noises (Hamilton fast Fourier analysis) during active suction at the liquid-air boundary. Noise maps at different flow rates were created for all five suction devices, and the proportion of extracted air was measured. The geometries of the three custom-made suction tips (new models 1, 2, and 3) were designed considering the insights after determining the key characteristics of the two standard suction models. RESULTS: The geometry of a suction device tip has significant impact on its noise emission. For the standard models, the frequency spectrum at higher flow rates significantly changes to high-frequency noise patterns (>3 kHz). A number of small side holes designed to prevent tissue adhesion lead to increased levels of high-frequency noise. Due to modifications of the tip geometry in our new models, we are able to achieve a highly significant reduction of noise level at low flow rates (new model 2 vs. standard models p < 0.001) and also the acoustic quality improved. Additionally, we attain a highly significant reduction of secondary air intake (new model 2 vs. the other models p < 0.001). CONCLUSION: Improving flow-relevant features of the geometry of suction heads is a suitable way to reduce noise emissions. Optimized suction tips are significantly quieter. This may help us to reduce noise-induced hearing damage in patients as well as stress of medical staff during surgery and should lead to quieter operation theatres overall. Furthermore, the turbulence reduction and reduced secondary air intake during the suction process are expected to result in protective effects on the collected blood and thus could improve the quality of autologous blood retransfusions. We are on the way to evaluate potential benefits.

[Meeting the needs of the European working time directive in german medical profession]. / Sollarbeitszeit und maximale Arbeitszeit bei angestellten Ärzten.

The legal obligation of the European Working Time Directive with its implementation into a German Working Hours Act requires German hospitals to give up old structures and requires the implementation of new working time models. The failure of the revision of the European Working Time Directive in April 2009 prevented that any changes of status quo might happen in the near future. Fundamental terms of the working law for the medical area have been elucidated and have been implemented into concrete calculation formulas. The planned working time has been clearly determined. Particularly, on-call duties and a signed "OptOut-declaration" have huge effects on the upper limit of the working time that is to be determined. Shift duty leads to the greatest limitations of the upper limit of the working time. The Working Hours Act defines the maximal, available, individual working time budget and thus the working time budget of a hospital and it limits the maximal availability of the service providers of a hospital as well as defining the maximal personnel costs. Transparency in this area lays the foundation for an effective time management and the creation of new working time models in accordance with the European Working Time Directive as well as the Working Hours Act and the "TVÄ" (labour contract for doctors at municipal hospitals). It is possible, with the knowledge of the maximal working time budget and the thereof resulting personnel costs, to calculate the economical revenues better. The reallocation of the working time of doctors enables efficiency enhancement. It is necessary to demand a clear definition of the tasks of doctors with the consequential discharge of tasks that should not/do not belong to the responsibilities of a doctor. This would lead to a more attractive working environment for doctors at hospitals and thus to an improvement of the care of the patients. The implementation of the European Time Directive is not to be seen as unrealizable, as has been generally heard; instead, it enables the urgently necessary structural reform at German hospitals.

Transposition of greater omentum in deep sternal wound infection caused by methicillin-resistant Staphylococci, with differing clinical course for MRSA and MRSE.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE) are an increasing problem in deep sternal wound infections (DSWI) after cardiac surgery. METHODS: Between 2005 and 2009, recalcitrant methicillin-resistant Staphylococcus was found in 21 patients with complicated DSWI, and a transposition of the greater omentum (TGO) was finally performed. A positive microbial culture at the time of procedure was present in all patients. The hospital course was reviewed discretely for MRSA and MRSE. RESULTS: Median patient age was 72.3 years (range 60.8-79.7); 76 % of patients were male. Time from the first sternal revision until consecutive open wound therapy due to re-infection and total hospital stay was longer for MRSA compared to MRSE (38 vs. 14 days, P = 0.003, and 141 vs. 91 days, P = 0.007, respectively). The period from cardiac surgery to TGO was likewise prolonged for MRSA (78 vs. 55 days, P = 0.045), whereas in-hospital mortality and one-year mortality rate did not differ. CONCLUSION: TGO remains a good treatment option for DSWI type IV. Microbial findings determine the clinical course; nevertheless in-hospital mortality remains low for both MRSA and MRSE infection.

Minimally invasive partial inferior sternotomy for congenital heart defects in children.

AIM: Minimally invasive approaches for repair of congenital heart defects have gained in popularity. Aim of the study was to evaluate the safety and efficiency of the partial inferior sternotomy approach to repair various congenital heart defects. METHODS: Since 1998, 100 children (55 males; mean age: 3.8 ± 3.7; mean weight: 15.1 ± 8.7 kg) were operated on via a limited median vertical skin incision and partial inferior sternotomy. Preoperative diagnoses were: ASD II (N.=46), sinus venosus defect with partial anomalous pulmonary venous connection (N.=12), partial AV-canal (N.=4), VSD (N.=35), tetralogy of Fallot (N.=2), and double chambered right ventricle (N.=1). Cannulation was always performed via the chest incision. RESULTS: There were no deaths. Mean cross-clamp time was 49.9 ± 30.6 minutes, and mean operation time 192 ± 46 minutes. Mean postoperative mechanical ventilation time, Intensive Care Unit stay and hospital stay were 9.7 ± 10.4 hours, 1.8 ± 0.7 days, and 12 ± 3.0 days, respectively. Complications included pneumothorax requiring drainage in 2 patients, atrioventricular block necessitating a permanent pacemaker in 1 patient. The incisions healed properly. All patients are in excellent condition after a mean follow-up of 32 ± 25 months. On echocardiography no residual defect was evident in 98 patients, and a mild mitral insufficiency in two patients operated on partial atrioventricular canal. CONCLUSION: The partial inferior sternotomy approach to congenital heart operations is less invasive than and cosmetically superior to full sternotomy with reduced postoperative pain and discomfort for the patients. This approach ensures a safe procedure with excellent exposure without additional incisions. It is our standard approach in infants/children with septal defects.

Histological changes in neonatal kidneys after cardiopulmonary bypass and deep hypothermic circulatory arrest.

BACKGROUND: Renal failure after open-heart surgery is a serious complication resulting in increased mortality and morbidity. The aim of the study was to find out whether different strategies for open-heart surgery would result in renal histological differences in a neonatal animal model. METHODS: The renal tissue of newborn piglets was examined after mild hypothermic cardiopulmonary bypass (CPB group; n = 10), deep hypothermic circulatory arrest (DHCA group; n = 8), instrumentation without extracorporeal circulation (sham; n = 3), and the data were compared with those of normal porcine neonatal kidneys (control; n = 6). The severity of tissue damage was graded using a 4-point scoring system (0: normal morphology, 3: severe damage). Apoptotic cells and granulocytes were counted. RESULTS: The histological score was higher in all groups compared with controls ( P < 0.05) and higher in the CPB group compared with the DHCA group ( P < 0.05). More apoptotic cells and granulocytes were found in the CPB group compared with controls and the DHCA group ( P < 0.05). CONCLUSIONS: Although changes in the kidney tissue of newborn piglets are detectable after any cardiac procedure, changes are more profound after cardiopulmonary bypass with mild hypothermia.

Surgical management of vascular graft infection in severely ill patients by partial resection of the infected prosthesis.

INTRODUCTION: In the presented retrospective study, we report on our results with partial resection of infected prosthetic grafts after aorto-bifemoral graft placement in eight male and three female patients. METHODS: In all 11 patients clinical signs of infection were observed and bacteriological cultures were positive. Three patients underwent immediate surgery for perforation of an aneurysm at the distal anastomosis, eight patients underwent elective surgery. In all cases silver-coated Dacron prostheses were implanted. Assessment of outcome was based on survival, limb salvage, persistent or recurrent infection, and prosthetic graft patency. RESULTS: In two cases, a partial wound dehiscence occurred which was treated with ambulant Vacuseal dressings for 16 and 21 days until secondary wound healing was achieved. In eight patients systemic markers of inflammation completed normalised within nine days. Follow-up CT-scans failed to demonstrate any signs of recurrent infection or peri-graft fluid collections. Patients were treated with specific antibiotic therapy for no more than three months. Post-operative bacteriological cultures were negative in all patients. The mean follow-up was 2.5+/-0.5 yrs. During follow-up, none of the patients died and there were no amputations. CONCLUSION: Despite only partial resection of the infected prostheses, the reported surgical procedure offers good results. This approach maybe particularly suitable for the treatment of elderly patients with prosthesis infections.

Dilated coronary sinus mimicking posterior left ventricular aneurysm.

Dilation of the coronary sinus is mostly a congenital lesion. As acquired lesion it was found to be associated with poor left ventricular function. In the present case an angiographic diagnosed posterior left ventricular aneurysm was during surgery found to be a dilated coronary sinus. Preoperative left ventricular function was normal.

Successful reconstruction of stripped superficial femoral vein.

A 69-year-old man who had hemorrhagic shock after inadvertent stripping of the right superficial femoral-popliteal vein during surgery for greater saphenous vein varicosis in another hospital was referred to us. Phlebography revealed a ruptured popliteal vein with intact profunda femoris and common femoral veins. The stripped superficial femoral-popliteal vein brought in a jar was reimplanted. Phlebography performed during the patient's follow-up visits in our outpatient clinic 11 months postoperatively showed a patent femoral vein.

Giant localized fibrous mesothelioma: an unusual large intrathoracic tumor.

BACKGROUND: Localized fibrous mesotheliomas are rare intrathoracic tumors arising from the pleural tissue. They are mostly benign tumors, with dimensions ranging from a small nodule to a large intrathoracic tumor. CASE: This paper describes the presence of giant localized fibrous mesothelioma filling the lower left pleural cavity, which developed over a 20-year period. Surgical resection of the tumor showed a large, localized fibrous mesothelioma 14 cm in diameter. CONCLUSIONS: The clinical manifestations of localized fibrous mesotheliomas are very variable. Small tumors may be asymptotic, while large tumors may cause respiratory, cardiac or metabolic symptoms. Complete surgical resection is the preferred treatment and is usually curative. Careful follow-up is indicated because recurrence may occur, even many years after the initial operation.

Left ventricular false aneurysm.

False aneurysms of the left ventricle develop after rupture of the ventricular wall in an area of pericardial adhesions. This complication of myocardial infarction is uncommon. Images of a post-infarction false aneurysm are presented.

Haemodynamic changes during minimally invasive coronary artery bypass surgery using high-dose esmolol.

UNLABELLED: We aimed to investigate the effects of high-dose esmolol on haemodynamics and oxygen extraction in minimally invasive direct coronary artery bypass (MIDCAB) surgery patients. METHODS: In 18 patients, heart rate (HR), mean arterial (MAP), central venous (CVP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and mixed venous oxygen saturation (Sv0(2)) were prospectively measured after induction of anaesthesia (T1), start of surgery (T2), during bypass grafting with beta-blockade (T3), and at the end of surgery (T4). RESULTS: Mean esmolol dose at T3 was 0.44+/-0.2mgkg(-1)min(-1). HR was unchanged, whereas significant decreases in mean CO (3.1+/-0. 8 vs 4.8+/-1.0lmin(-1)m(-2), pre-esmolol), MAP (53+/-10 vs 89+/-14mmHg), and SvO(2) (65+/-10 vs 81+/-4%) were observed during esmolol administration. All haemodynamic parameters normalized immediately after termination of esmolol (T4). CONCLUSIONS: Despite unchanged HR esmolol reduced CO and MAP suggesting a favorable reduction of myocardial oxygen consumption. Mean Sv0(2) during esmolol administration reflects an acceptable ratio of whole-body oxygen delivery and consumption. Haemodynamic changes with high-dose esmolol during MIDCAB surgery remain within safety margins.

Pulmonary arteriovenous fistula drainage into the left atrium.

Arteriovenous fistulas with venous drainage into the left atrium are a rare anomaly. Although the etiology of pulmonary arteriovenous fistulas is unknown, these abnormalities are considered to have occurred during early fetal development. A case of this malformation in a 72-year-old woman successfully treated by surgery is described.

Pericardectomy for chronic constrictive pericarditis: risks and outcome.

From 1970 to 1990, 71 consecutive patients (51 men and 20 women) had pericardectomy for chronic constrictive pericarditis. The mean age was 44.2 +/- 16.1 years. In the preoperative state 2.8% were in NYHA class I, 18.3% in II, 43.6% in III and 35.2% in IV. The operative approach was median sternotomy in 93% and left anterolateral thoracotomy in 7%. The early mortality rate (within 30 days after operation) was 5.6%. All four early deaths were female (P < 0.001), in the preoperative state the patients were classified as NYHA class IV (P < 0.01). These patients had a significantly higher preoperative mean right atrial pressure then survivors (21.5 +/- 8.5 mmHg vs 13.6 +/- 5.6 mmHg, P < 0.005). Follow-up was obtained for 65 patients (91.5%) and averaged 11 +/- 5.8 years (the longest period was 21.5 years). Actuarial survival at 5, 10, 15 and 20 years for all patients was 84.6% +/- 4.5%, 80.1% +/- 5.3%, 70.5% +/- 6.9% and 65.8% +/- 7.9%, respectively. In the preoperative state 10 of the 12 late deaths (83%) were classified NYHA class IV and the remaining ones class III. Of the 49 patients alive 23% belong to NYHA class I, 42% to II and 35% to III; none is in class IV. Negative predictors of survival were found to be preoperative NYHA class IV (P < 0.01), low-voltage electrocardiogram (ECG) (P < 0.01), ascites (P < 0.01), dyspnea at rest (P < 0.05) and hyperbilirubinemia (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)