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PubMed2007

Single trial somatosensory evoked potential extraction with ARX filtering for a combined spinal cord intraoperative neuromonitoring technique.

BACKGROUND: When spinal cord functional integrity is at risk during surgery, intraoperative neuromonitoring is recommended. Tibial Single Trial Somatosensory Evoked Potentials (SEPs) and H-reflex are here used in a combined neuromonitoring method: both signals monitor the spinal cord status, though involving different nervous pathways. However, SEPs express a trial-to-trial variability that is difficult to track because of the intrinsic low signal-to-noise ratio. For this reason single trial techniques are needed to extract SEPs from the background EEG. METHODS: The analysis is performed off line on data recorded in eight scoliosis surgery sessions during which the spinal cord was simultaneously monitored through classical SEPs and H-reflex responses elicited by the same tibial nerve electrical stimulation. The single trial extraction of SEPs from the background EEG is here performed through AutoRegressive filter with eXogenous input (ARX). The electroencephalographic recording can be modeled as the sum of the background EEG, which can be described as an autoregressive process not related to the stimulus, and the evoked potential (EP), which can be viewed as a filtered version of a reference signal related to the stimulus. The choice of the filter optimal orders is based on the Akaike Information Criterion (AIC). The reference signal used as exogenous input in the ARX model is a weighted average of the previous SEPs trials with exponential forgetting behavior. RESULTS: The moving average exponentially weighted, used as reference signal for the ARX model, shows a better sensibility than the standard moving average in tracking SEPs fast inter-trial changes. The ability to promptly detect changes allows highlighting relations between waveform changes and surgical maneuvers. It also allows a comparative study with H-reflex trends: in particular, the two signals show different fall and recovery dynamics following stressful conditions for the spinal cord. CONCLUSION: The ARX filter showed good performances in single trial SEP extraction, enhancing the available information concerning the current spinal cord status. Moreover, the comparison between SEPs and H-reflex showed that the two signals are affected by the same surgical maneuvers, even if they monitor the spinal cord through anatomically different pathways.

Algorithms↗
PubMed2004

The accuracy of trained nurses in pre-operative health assessment: results of the OPEN study.

We quantified the accuracy of trained nurses to correctly assess the pre-operative health status of surgical patients as compared to anaesthetists. The study included 4540 adult surgical patients. Patients' health status was first assessed by the nurse and subsequently by the anaesthetist. Both needed to answer the question: 'is this patient ready for surgery without additional work-up, Yes/No?' (primary outcome). The secondary outcome was the time required to complete the assessment. Anaesthetists and nurses were blinded for each other's results. The anaesthetists' result was the reference standard. In 87% of the patients, the classifications by nurses and anaesthetists were similar. The sensitivity of the nurses' assessment was 83% (95% CI: 79-87%) and the specificity 87% (95% CI: 86-88%). In 1.3% (95% CI: 1.0-1.6%) of patients, nurses classified patients as 'ready' whereas anaesthetists did not. Nurses required 1.85 (95% CI: 1.80-1.90) times longer than anaesthetists. By allowing nurses to serve as a diagnostic filter to identify the subgroup of patients who may safely undergo surgery without further diagnostic workup or optimisation, anaesthetists can focus on patients who require additional attention before surgery.

Adult↗
PubMed2004

Extended interval for retrieval of Günther Tulip filters.

PURPOSE: To evaluate the Gunther Tulip vena cava filter with regard to ease of placement, complications, and retrieval over long time periods. MATERIALS AND METHODS: In 53 patients (ratio of men to women, 24:29; mean age, 52.8 years) retrievable Gunther Tulip filters (Vena Cava M Reye Filter Set; William Cook Europe, Denmark) were inserted. Indications included planned major surgery with recent pulmonary embolus or high pulmonary embolus risk (n = 16), extensive ilio-femoral thrombus (n = 11), deep vein thrombosis with anticoagulant complications (n = 9), breakthrough pulmonary embolus despite anticoagulant therapy (n = 4), and contraindication to anticoagulant therapy (n = 13). All patients were followed-up for immediate and long-term complications. RESULTS: Fifty-three filters were successfully placed in 52 of 53 patients, yielding a success rate of 98.1%. Nineteen patients underwent attempted retrieval of their filter. Sixteen of 19 retrieval procedures were successful (84%). In three patients, the filter could not be removed on attempted retrieval (extensive filter thrombus in two patients and attachment to the wall in one patient). One patient received two filters, which were both successfully retrieved at a later date. Median implantation time for retrievable filters was 34 days (range, 7-126 days). Mean follow-up for patients with permanent filters was 13 months. Two major complications (pneumothorax and break through pulmonary embolus) and three minor complications (right internal jugular vein thrombosis in two patients and transient Horner's Syndrome in one patient) were recorded. CONCLUSION: Insertion and retrieval of filters is safe and feasible. Preliminary data suggest that Gunther Tulip filter retrieval is feasible over and above the manufacturer's recommended retrieval interval of 14 days.

Adult↗
PubMed2006

The macular hole: histopathologic studies.

OBJECTIVE: To delineate the light and electron microscopic features of tissue removed at the time of macular hole surgery. METHODS: The ocular fluid specimens were concentrated using Millipore filters and stained with a modified Papanicolaou and the periodic acid-Schiff stains in 697 cases. In 92 cases, surgically isolated tissue was processed and examined by electron microscopy. RESULTS: The findings in the specimens studied by the Millipore filter technique included vitreous strands; cellular fragments in 108 cases (13.3%); fibrocellular fragments in 75 (9.2%); and fragments of internal limiting lamina (ILL) of the retina in 104 (12.8%). Findings in the 92 specimens with tissue studied by electron microscopy included native vitreous collagen in 48 cases (52.2%); new collagen in 6 (6.5%); native and new collagen in 1 (1.2%); ILL of the retina in 54 (58.7%); and a variety of cells in 22.5% of cases, including fibrocytes, myofibrocytes, fibrous astrocytes with and without myoblastic features, Mueller cells, retinal pigment epithelium with and without myoblastic features, and inflammatory cells. The organization of the tissue elements included a cellular layer along one surface of a layer of cortical vitreous in 18 cases, cortical vitreous along the inner surface of the ILL of the retina in 10, and cortical vitreous sandwiched between the ILL of the retina and a layer of cells in 9. CONCLUSIONS: Tangential traction induced by fluid movements affecting the cortical vitreous is a major factor in the pathogenesis of idiopathic macular holes. Cellular proliferation is a secondary change seen in 22.2% of cases.

Basement Membrane↗
PubMed1998

Transcatheter closure of an anomalous venous connection by a novel method.

Left superior vena cavae draining to the left atrium have traditionally been treated with surgical ligation. Advances in cardiac catheterization have made transcatheter closure a viable alternative to surgery. We report on an innovative method using a Greenfield filter and Gianturco coils for closure of a persistent left superior vena cava.

Abnormalities, Multiple↗
PubMed2000

Closed circuit cardiopulmonary bypass with centrifugal pump for open-heart surgery: new trial for air removal.

The purpose of this study is to examine the efficiency of venous air removal with a new cardiopulmonary bypass (CPB) circuit design for conventional open-heart surgeries. A main concern with a closed circuit for open-heart surgeries is air entrainment into the venous line. A venous filter was placed proximal to the centrifugal pump. The circuit proximal to the centrifugal pump was divided into two lines; one line was attached to the venous reservoir outlet. By clamping the line to the reservoir, this circuit becomes closed. Negative pressure was applied to the purge line connected to the venous reservoir for venous air removal. Micro bubbles were measured at two locations, both distal to the venous and arterial filters. When the injection rate reached 100 ml/min, with the air-injection over 30 s, micro bubbles greater than 40 micro were observed at the outlet of venous filter. However, there was no micro bubble greater than 40 micro detected at the outlet of arterial filter. Although micro bubbles greater than 40 micro were not detected at the outlet of the arterial filter up to the injection rate of 300 ml/min, when the injection rate reached 400 ml/min, micro bubbles greater than 50 microm were detected distal to the arterial filter. From this examination, we determined that air entrained in the venous line up to approximately 300 ml/min is automatically removed by this method with the pressure-balanced condition. This pressure balance means that resistance of venous return, gravity siphon, negative pressure by centrifugal pump, and negative pressure applied to the air-purge line of the filter are balanced; that is, the venous return is sufficient, and the venous reservoir volume is kept stable. From this study we determined that this circuit design efficiently removes the entrained air in the venous line.

Air↗
PubMed1986

Central auditory function following anterior sectioning of the corpus callosum.

This paper describes auditory findings for eight patients with anterior sections of the corpus callosum. Peripheral (pure tone and speech recognition) and five central auditory tests were administered to each of the eight patients prior to surgery and then again approximately 2 weeks after surgery. The central tests administered included a low-pass filtered speech test, the frequency patterns perception test, and three dichotic speech tests. Mean scores for the peripheral tests fell grossly within the normal range preoperatively and showed little change postoperatively. Similarly, scores on the central tests, though somewhat more variable, did not show any obvious differences upon pre- and postsurgical comparison. A comparison of these results with those reported previously for patients with complete commissurotomies (Musiek, Kibbe, and Baran. Semin Hear 1984;5:219-29) revealed that as a group, patients with anterior sections of the corpus callosum showed fewer postsurgery deficits than did the subjects with complete commissurotomies. The lack of an apparent auditory effect in the anterior group is believed to have an anatomical basis.

Adult↗
PubMed1975

New light on the transmissibility of viral hepatitis in dental practice and its control.

Evidence of an increase in the nonparenteral spread of viral hepatitis is of much concern in dentistry and supports the need for sterilization of all instruments used in intraoral treatments. Methods for the rapid sterilization of all dental handpieces and air-water syringes are still inadequate for routine clinical use. It may be possible to improve surface disinfection of these items by more thorough, repeated cleansing with common disinfectants and by the use of stronger germicidal agents such as aldehydes. However, for handpieces and some other equipment, effective sterilization methods must be developed or the instruments must be modified so they can be safely and rapidly sterilized. Surface disinfectants that will destroy hepatitis viruses are needed for disinfection of the dental unit. The use of gloves is also an important consideration for the protection of both the dentist and his patient. The high attack rate of hepatitis among surgeons, as well as patient protection, make the wearing of gloves during surgery imperative. Evidence that aerosolborne viruses would be removed by filtered laminar air flow or by face masks is not available, but use of these devices reduces exposure of personnel to aerosols in general and appears to be highly desirable. Sterilization of all possible instruments is advocated for use in all institutions and dental offices. Careful monitoring of the effectiveness of sterilization also is advocated. These concepts and new information on which they are based should be incorporated into dental curriculums and continuing education courses for all dentists and auxiliary personnel.

Antigens, Viral↗
PubMed2005

Impact of postoperative shed blood transfusion, with or without leucocyte reduction, on acute-phase response to surgery for total knee replacement.

BACKGROUND: In patients undergoing total knee replacement (TKR) most blood loss occurs postoperatively and return of unwashed filtered shed blood (USB) from postoperative drainage may represent an alternative to allogeneic blood transfusion (ABT). We evaluated the impact of USB return, with or without leucocytes, on the acute-phase response (APR) after TKR. PATIENTS AND METHODS: Forty-eight TKR patients, intended to receive postoperative USB, entered the study. Blood samples were obtained before and 6, 24, 72 h and 7 days after surgery, and from the USB before and after it passed through a 40-microm filter (Group F40) or a leucocyte-reduction filter (Group LRF). Haematimetric parameters, APR proteins (albumin, prealbumin, ceruloplasmin, haptoglobin, C-reactive protein), complement C3 and C4, and cytokines (IL-1beta, IL-6, IL-8, IL-10, and TNF-alpha) were measured in all samples. RESULTS: Twenty-eight patients (Group F40=14, Group LRF=14) received a mean of 1.2 USB units, without any clinically relevant incident, and did not need additional ABT. Sixteen out of the 20 remaining patients who received neither USB nor ABT served as a control group for the postoperative APR study. All patients showed the typical postoperative APR profile and there were no significant differences between groups for APR parameters, postoperative complications, or hospital stay. CONCLUSIONS: Postoperative blood salvage and return, with or without a LRF, after TKR does not present any clinically relevant side-effects and does not modify APR induced by surgery. These findings seem to confirm the clinical experience that postoperative USB return is safe and questions the beneficial effect of using LRF.

Acute-Phase Reaction↗
PubMed2004

Cardiac effects of carbon monoxide and ambient particles in a rat model of myocardial infarction.

Ambient air pollution is a complex mixture of particulate matter (PM) and gaseous pollutants such as carbon monoxide (CO). The effect of exposure to CO, alone or in combination with ambient PM, on arrhythmia incidence is unclear. To evaluate these effects, left-ventricular myocardial infarction was induced in Sprague-Dawley rats by thermocoagulation. Diazepam-sedated rats were exposed (1 h) to either filtered air (n = 40), CO (35 ppm, n = 19), concentrated air particles (CAPs, median concentration = 350.5 microg/m(3), n = 53), or CAPs and CO (CAPs median concentration = 318.2 microg/m(3), n = 23), 12-18 h after surgery. Each exposure was immediately preceded and followed by a 1 h exposure to filtered air (pre-exposure and post-exposure periods, respectively). The CO target dose of 35 ppm is related to the 1 h U.S. National Ambient Air Quality Standard. Surface electrocardiograms were recorded and heart rate and arrhythmia incidence were quantified. CO exposure reduced ventricular premature beat (VPB) frequency by 60.4% (p = 0.012) during the exposure period compared to controls. This effect was modified by both infarct type and the number of pre-exposure VPBs, and was not mediated through changes in heart rate. Overall, CAPs exposure increased VPB frequency during the exposure period, but this effect did not reach statistical significance. This effect was modified by the number of pre-exposure VPBs. Overall, neither CAPs nor CO had any effect on heart rate, but CAPs increased heart rate in specific subgroups. No significant interactions were observed between the effects of CO and CAPs. In this animal model, the responses to CO and CAPs are distinctly different.

Air Pollutants↗
PubMed1977

Reopening of occluded filtering blebs by argon laser photocoagulation.

We attempted to re-establish filtration in 11 glaucomatous eyes of patients who had undergone fistulizing surgery in the past, had poor or no filtration at various periods of time after surgery, and intraocular pressure above normal levels. Our technique consisted of applying an argon laser beam to the anterior chamber angle at the sclerotomy site of previous filtering and anterior to the iridectomy. Approximately 200 spots of 50 mu size were applied to this target with the help of a Goldmann prismatic goniolens. In five of 11 eyes the fistulizing blebs showed signs of activity shortly after the laser treatment with normalization of IOP during a follow-up period of over one year. Success was obtained in eyes with incomplete scarring of their fistulizing blebs with poor and nonfunctioning filtering cysts. Pigmentation of the target at the occluded sclerotomy site was significant.

Adult↗
PubMed1994

Polymorphonuclear leucocyte migration response in uneventful wound healing following trauma surgery. A contribution to the search for objectifiable criteria in wound healing monitoring.

In a study of the clinical importance of polymorphonuclear granulocytes (PMN) for the monitoring of wound healing we investigated the postsurgical course of nine patients all of whom had undergone trauma surgery and had no wound complications. The "stimulated random PMN locomotion" was evaluated by a new migration filter device which preserves the cells in their genuine priming state, simulating in vivo conditions. The percentage of all activated PMN, expressed by the total migration index (TMI) reflected the highest median immediately after surgery (Zmax = 30.1%) and dropped to the lowest value on day 13 (Zmin = 13.9%). The mean invasion depth (T/2) of the cells along the migration distance into the filter showed only slight variations over time. The neutrophil migration activity (NMA), described by T/2 and TMI, behaved in a similar way to TMI. In studying physiological healing, preliminary results indicate that TMI, which expresses PMN activation, is an efficient tool in the postoperative monitoring of patients, and might in the future serve as a basis for an early warning system for wound healing complications.

Adult↗
PubMedDate not supplied

The use of retrievable inferior vena cava filters in trauma: implications for the trauma team.

Prevention of venothromboembolic complications remains a challenge in trauma care. Guidelines for prophylaxis published by the Eastern Association for the Surgery of Trauma stratify patients by risk and recommend therapies based on scientific evidence. New innovations such as retrievable inferior vena cava filters are being used by trauma surgeons for patients at risk for pulmonary embolism but in whom anticoagulation is contraindicated. Some available devices offer a limited timeframe for retrieval beyond which the device becomes permanent. The increased utilization of this technology presents case management challenges to trauma teams. Patients who are unreliable or may be difficult to track posthospitalization (homeless, migrant workers, prison system, etc.) run the risk of not having their filters removed as initially intended. Nurses can play a critical role in helping to manage and direct the discharge plan and case management of trauma patients with retrievable inferior vena cava filters.

Algorithms↗
PubMed2003

[Efficacy of an antibacterial filter for preventing contamination of respiratory function diagnostic equipment].

OBJECTIVES: Devices to assess lung function are a potential source of nosocomial infection. Our aims in this study were: 1) to determine the efficacy of an antimicrobial filter to prevent contamination of a multifunctional device; 2) to assess the ability of the filter to prevent cross contamination of individuals being tested; and 3) to evaluate the efficacy of the recommendations of the Spanish Society of Respiratory Diseases and Thoracic Surgery for disinfecting lung function equipment. DESIGN: In this prospective, randomized study in two phases we used filters in phase 1 but not in phase 2. A pharyngeal swab culture was started within 7 days of a patient's lung function test. Swab samples for culturing were taken from three different places in the equipment at the beginning and end of each working day. PATIENTS: Sixty-five patients (31 in phase 1 and 34 in phase 2) were studied. Thirty-two (49.2%) were men and the mean age was 49.4 15.7 years. RESULTS: Significantly less equipment contamination was found in phase 1 (4.2%) than in phase 2 (21%). We detected no cases of cross contamination using the criteria in this study. No cultures from any of the samples taken before exploration were positive. CONCLUSIONS: a) The antimicrobial filter used is effective for preventing the contamination of lung function testing equipment, b) throughout both phases of the study, we observed no cross contamination of patients tested, such that we cannot conclude that the antimicrobial filter is effective for preventing possible nosocomial infections, c) the recommendations of SEPAR for disinfecting lung function equipment are effective.

Cross Infection↗
PubMed2001

[Analysis of filtration according to implant type after deep sclerectomy in the rabbit].

PURPOSE: The purpose of this study was to compare the aqueous humor outflow using three type of implants after deep sclerectomy. A numeric imaging system with ICG and fluorescein angiography was used. The evolution over time was recorded, while filtration and outflow facility were measured. MATERIAL AND METHODS: Numeric imaging system with ICG and fluorescein angiography were performed before and after deep sclerectomy at regular intervals after surgery. Both resorbable (collagen) and non-resorbable (hema) intrascleral devices have been tested in eight rabbits. The resorption time of the collagen implants has been monitored using UBM technique. The outflow facility was measured with the technique of anterior chamber canulation and constant pressure method. RESULTS: The resorbable collagen implants could be observed with UBM and angiography during the first six weeks post-operatively. The image of the non-resorbable Hema implant remained clearly visible over time. New drainage vessels were observed around the filtering bleb. The filtration significantly increased as the outflow facility improved after surgery, while the intraocular pressure remained stable over time. CONCLUSION: This conjunction of UBM, angiography and outflow measurement allowed us to study and compare three types of implants used as space maintainer after deep sclerectomy, and analyse their effect on the aqueous filtration and outflow facility.

Animals↗
PubMedDate not supplied

Updating on intraoperative light-induced retinal injury.

We are presenting the state of knowledge concerning intraoperative light-induced retinal injury, considered to be a combination of photic retinopathy and retinal photocoagulation. It may arise from retinal light exposure to the operating microscope or to the fiberoptic endoilluminator. Ultraviolet and short-wavelength visible light are more dangerous than longer wavelength light. Many risk factors may facilitate the onset of this iatrogenic disease following surgery. Many aspects of the retinal damage are still poorly understood. Many mid light-induced retinal injuries probably remain undiagnosed in routine postoperative examination. Current appropriate light filters are not the definitive solution. Appropriate precautions should be taken during both anterior segment and vitreoretinal surgery.

Aged↗
PubMed1993

Value of the P-wave signal-averaged ECG for predicting atrial fibrillation after cardiac surgery.

BACKGROUND: Atrial fibrillation (AF) is a commonly encountered arrhythmia in clinical practice, and it occurs frequently after cardiac surgery. The P-wave signal-averaged (SA) ECG noninvasively detects atrial conduction delay. Prior studies have described greater P-wave prolongation in patients with a history of AF, but prospective studies have not been performed. METHODS AND RESULTS: Consecutive patients undergoing cardiac surgery were enrolled. The P-wave SAECG was recorded before surgery from three orthogonal leads using a sinus P-wave template and a cross-correlation function. The averaged P wave was filtered with a least-squares-fit filter and combined into a vector magnitude, and total P-wave duration was measured. Patients were observed after cardiac surgery for the development of AF. One hundred thirty patients were enrolled, and 33 (25%) developed AF 2.6 +/- 2.0 days after surgery. Patients with AF more often had left ventricular hypertrophy on ECG (P < .05) and had a lower ejection fraction (P < .05). The P-wave duration on the SAECG was significantly longer in the AF patients than in those without AF: 152 +/- 18 versus 139 +/- 17 milliseconds (P < .001). An SAECG P-wave duration > 140 milliseconds predicted AF with sensitivity of 77%, specificity of 55%, positive predictive accuracy of 37%, and negative predictive accuracy of 87%. The likelihood of experiencing AF was increased 3.9-fold if the SAECG P-wave duration was prolonged. P-wave SAECG results were independent of other clinical variables by multivariate analysis. CONCLUSIONS: The P-wave duration recorded with the SAECG is a potent, accurate, and independent predictor of AF after cardiac surgery.

Aged↗
PubMed2006

Post-operative unwashed shed blood transfusion does not modify the cellular immune response to surgery for total knee replacement.

BACKGROUND: In patients undergoing total knee replacement (TKR), most blood loss occurs post-operatively, and the return of unwashed filtered shed blood (USB) from post-operative drainage may represent an alternative to allogeneic blood transfusion (ABT). We evaluated the impact of USB return on the cellular immune response (CIR) after TKR. PATIENTS AND METHODS: Forty TKR patients, intended to receive post-operative USB, entered the study. Blood samples were obtained before and 6 h, 24 h, 72 h and 7 days after surgery, and from USB, after it had been passed through a 40-microm filter. Full blood cell counts, lymphocyte subsets and immunoglobulins (IgA, IgG, IgM) were measured in all samples. A set of clinical data was collected from each patient. RESULTS: Twenty-four of the 25 patients received a mean of 1.2 USB units and did not need additional ABT (USB group). Twelve of the 15 remaining patients who received neither USB nor ABT served as a control group for the post-operative CIR study. All patients showed a post-operative decrease in T-cell and natural killer (NK) cell counts, but not B-cell counts, and there were no significant differences between the groups with regard to CIR parameters, post-operative infection or hospital stay. CONCLUSIONS: Post-operative salvage and return of USB after TKR does not seem to increase the post-operative infection rate or hospital stay, and does not modify CIR induced by surgery. These findings add to the clinical experience that post-operative USB return, as a source of autologous blood, is safe, and questions the beneficial effect of blood washing.

Aged↗