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Biomedical subjects

Z J Twardowski

Publications and source records attributed to Z J Twardowski.

At least 19 recordsLinked to original sources
PubMed1996

Four-year experience with swan neck presternal peritoneal dialysis catheter.

The swan neck presternal catheter is composed of two flexible (silicon rubber) tubes joined by a titanium connector at the time of implantation. The exit site is located in the presternal or parasternal area. The catheter located on the chest was designed to reduce the incidence of exit site infections compared with peritoneal dialysis catheters with abdominal exit sites. From August 1991 to May 1995, 24 swan neck presternal catheters have been implanted in 24 patients for the following reasons: obesity nine patients, ostomies three patients, a suprapubic catheter one patient, previous problems with abdominal catheters two patients, desire to use a bathtub five patients, need to use a whirlpool one patient, need to wear sweatpants with an elastic waistband one patient, and body image two patients. In the same period, 47 abdominal swan neck catheters were implanted in 44 patients who preferred catheters with the exit on the abdomen. Presternal catheters tended to perform better regarding exit and tunnel infections, even though they were implanted in several patients in whom regular catheters with the exit on the abdomen would be difficult or impossible to implant. Two-year survival probability of presternal catheters was 0.88 +/- 0.14 (+/- SE). Recurrent/refractory peritonitis was the only reason of catheter failure. The differences in results between presternal and abdominal catheters were statistically insignificant; only the use of antibiotics to treat exit site infection was significantly higher with abdominal catheters. Patient acceptance of the exit position was good; at least seven patients preferred presternal catheter for psychological or body image reasons. We conclude that the swan neck presternal catheters provide excellent results comparable to those achieved with swan neck abdominal catheters. The catheter seems suitable for any patient commencing peritoneal dialysis and is particularly useful in extremely obese patients (body mass index > 40 kg/m2) and those with ostomies. The catheter exit location in the chest may be preferred by some patients, both men and women, for psychological or body image reasons. No specific contraindications to the presternal catheter implantation have been identified.

Abdomen↗
PubMed1996

Daily home hemodialysis: a hybrid of hemodialysis and peritoneal dialysis.

Despite that routine home hemodialysis, performed with thrice weekly frequency, had provided the best clinical results of any dialysis modality, it has been losing competition to center hemodialysis and home peritoneal dialysis. The main reason for this paradox is a lack of suitable equipment for home hemodialysis. Contrary to peritoneal dialysis, which is easy to learn and perform without need for a helper, home hemodialysis is difficult because the kidney machines are not designed for home therapy. Daily hemodialysis provides even better results than routine home hemodialysis. Several studies showed excellent intradialytic and interdialytic tolerance. In spite of these results the method is used only in a few centers. There are two major reasons for this incongruity: time requirement for the patient and the cost for the provider. With more frequent dialysis, more time is spent on machine setup, tear down, and cleaning. If supplies are not reused, the cost of dialysis increases substantially with increased frequency of dialysis. Daily home hemodialysis may become practical with a new machine. Three components seem crucial for this device: a built-in water treatment system; a simple, small, positive pressure, single pass, batch dialysate system; and a reusable extracorporeal circuit, automatically cleaned and disinfected daily. Daily home hemodialysis performed with the new artificial kidney system may be considered as a hybrid of hemodialysis and peritoneal dialysis. High efficiency is taken from hemodialysis; simplicity is taken from peritoneal dialysis.

Costs and Cost Analysis↗
PubMed1996

Exit-site study methods and results.

Contrary to peritonitis, where the clinical presentation is clearly different from that of normal, there is a spectrum of appearances from uninfected to infected exit sites. This led to imprecise definitions of exit-site infection, difficulties in interpreting the results of various studies, and many, varied treatment recommendations. We have performed 565 evaluations of 61 healed exit sites in 56 patients. The exit and the sinus were inspected using a Zeiss prism loupe with 4.5x magnification for the presence, absence, intensity, and/or characteristics of specific attributes such as swelling, color, crust, drainage, granulation tissue, and epithelium in the sinus. Pictures of the external exit and the visible sinus tract were then drawn and photographs of the exit site and visible sinus tract were taken. Visual attributes discerned by loupe inspection were verified by review of photographs. A new classification was developed with six distinct categories of exit appearances: acute infection, chronic infection, external cuff infection, equivocal, good, and perfect. Finally, the category of traumatized exit was established, because trauma may result in various appearances. The outcomes in each category were correlated with treatment measures in a 5-year longitudinal study. The validity of this classification and its applicability to clinical practice was subjected to further investigation in a cross-sectional study. Forty-five patients were evaluated only once by ZJT using a Zeiss prism loupe and by the primary nurse, who used a handheld magnifier. The features were recorded and classification was made. The results of loupe and magnifier evaluations were then compared regarding agreement in discerning features. In 41 evaluations (91%) there was agreement. The new classification may be useful in making treatment decisions, in reporting exit-site infection data, and in designing improved prospective, randomized studies.

Adult↗
PubMed1996

Exit-site healing post catheter implantation.

The study goals were (1) to describe the natural healing process post peritoneal dialysis catheter implantation; (2) to discern factors that predispose to exit infection; (3) to recognize signs of early exit-site infection; and (4) to ascertain the influence, if any, of the healing process on subsequent peritonitis rates and final catheter outcomes. There were 226 evaluations of 43 exits [range 3-6 per exit, mean 5.2 + or - 1.1 (SD)] in 41 patients. Eleven exits were in the parasternal area and 32 exits were in the abdomen. Exit sites and sinus tracts were examined weekly for 6 weeks with a magnifying loupe and macro-photographed. Cultures were taken from sterile saline sinus washouts, periexit smears, and nares. Exit sites were categorized into four types: (1) fast-healing exits had no drainage or minimal moisture deep inside by the third week; epidermis started to enter into the sinus within 2-3 weeks, progressed steadily, and covered at least half the visible sinus tract 4-6 weeks after implantation; (2) in slow-healing exits without infection, epidermis started to enter into the sinus after 3 weeks or progressed slowly and did not cover half the visible sinus by 5 weeks; the sinus might have had serous or serosanguineous, but never purulent, drainage persistent up to 4 weeks; (3) healing interrupted by infection initially looked identical to the fast-healing exit, but within 6 weeks the epidermis did not progress or regress, granulation tissue became soft or frankly fleshy; drainage increased and/or became purulent; (4) in slow-healing exits due to early infection, granulation tissue became soft or fleshy and/or drainage became puru lent by 2-3 weeks; sinus epidermization was delayed or progressed slowly, only after infection was appropriately treated. Compared with patients with fast-healing exits, patients with early infected exits were more likely (although not significantly) to be diabetics, to have an abdominal catheter, wound hematoma, higher body mass index, and higher percentage of positive cultures for Staphylococcus aureus in nares. Early colonization of the exit was the most significant factor in determining the healing pattern: the later the colonization, the better the healing. Positive culture from either washout or periexit smear one week after implantation was associated with early exit infection, a higher peritonitis rate, and a high probability of catheter loss due to an exit/tunnel infection, and higher peritonitis rate; however, the time to the first peritonitis episode was not shorter than in the groups with later exit colonization. We postulate that exit infections and peritonitis rates may be decreased by delaying exit colonization using prophylactic antibiotics for at least 2 weeks after implantation and sterile exit dressing procedure for the entire healing time of approximately 6 weeks.

Adult↗
PubMed1996

Recommendations for treatment of exit-site pathology.

Good local care including measures to prevent trauma keeps healthy exit sites free of infection. Acute infection can be cured with aggressive therapy. Chronic infection may progress to cuff infection, which even when treated, may progress to peritonitis. Cuff and tunnel infections require deroofing, cuff shaving, and/or catheter removal. Therapy may prolong the life of a catheter. An equivocal exit site requires aggressive therapy in order to achieve cure. Local care of the exit should include measures to prevent trauma. Should trauma occur, aggressive therapy that includes a systemic antibiotic should be instituted immediately. Aggressive therapy is particularly indicated during the healing period. Prophylactic antibiotics, systemic or topical, are indicated in trauma, recurrent infection, and may be beneficial during the healing period.

Bacterial Infections↗
PubMed1996

Effects of bicarbonate dialysis solution on peritoneal transport in rats.

We studied the effects of bicarbonate dialysis solution (TB 1.36) on the peritoneum in our rat model of dialysis. Twenty-four male Sprague-Dawley rats were divided into two groups (n = 12 each). One group was dialyzed with standard 1.36% Dianeal PD-2 (L-group); the other group was dialyzed with TB 1.36 (B-group). After break-in dialysis after catheter insertion, the animals were dialyzed twice daily with 30 mL of the designated dialysis solution for four weeks. White blood cell count with differentials and microbiological culture of the dialysate were examined once a week to detect peritonitis. A peritoneal equilibration test (PET) was performed on the eighth and thirty-sixth days. The dialysate was obtained at 0, 2, and 4 hours; a blood sample was taken at 0 hour. Peritoneal tissue specimens were obtained after the second PET. Histological score was calculated based on the degree of thickening of the peritoneum. Five rats in L-group and three rats in B-group suffered from peritonitis. Two other rats in B-group had complications and did not complete the experiment. Therefore, seven rats from each group finished the experiment, and the PET data was analyzed. The peritoneal transport property of B-group did not change over time, while, in L-group it became less permeable on the thirty-sixth day. Fibrotic thickening of the peritoneum was observed in both groups, however, the histological score was slightly lower in B-group. These results suggest that the bicarbonate dialysis solution may be less harmful to the peritoneum.

Animals↗
PubMed1996

Evaluation of healing and external tunnel histology of silver-coated peritoneal catheters in rats.

A previous study showed that silver-coating peritoneal catheters tended to decrease the incidence of early exit-site infections in rats. This study was designed to further evaluate the healing, biocompatability, and external tunnel morphology of standard and silver-coated catheters. Catheters were coated with silver by an ion beam-assisted process. Fourteen male Sprague-Dawley rats underwent implantation of either a standard or silver-coated double-cuff peritoneal catheter. Weekly observation and photographs documented exit-site characteristics. Erythema, exudate, loose fit, and poor hair growth were evidence of an inflamed exit. Overt infection was indicated by the presence of three or more of the following: erythema, purulent exudate, exuberant granulation tissue, loose fit, and poor hair growth. Animals were sacrificed at six weeks, and catheters were removed and processed for histology of the external tunnel. Multiple measurements were taken using a Filar eyepiece, and data were expressed as a mean of several readings. Inflammation, vascularity, and fibrosis were judged semiquantitatively. At the end of six weeks, six of the seven exits of the silver catheters showed excellent healing, while one exit site had signs of excessive inflammation. Four of the exit sites of the standard catheters healed well, two were inflamed, and one was overtly infected. The sinus tract of the standard and silver catheters had similar characteristics: keratinized and nonkeratinized epithelium lined the external part of the sinus tract and merged into granulation tissue. A fibrous sheath was noted in some sinus tracts between the granulation tissue and the cuff. The cuff evoked a foreign body reaction, with fibrosis, multiple giant cells, and vascularization. Poorly healing or infected sinus tracts had highly vascular granulation tissue with overlying exudate. The cuff of these catheters had marked inflammation and scanty giant cells, although collagen bundle thickness was similar to the well-healing catheters. In conclusion, silver-coating potentially enhances healing of the exit sites of peritoneal catheters. Additionally, the similarity of the tunnel histomorphology of standard and silver catheters confirms the favorable biocompatibility of silver.

Animals↗
PubMed1995

Expected white blood cell counts and differentials in a rat model of peritoneal dialysis.

OBJECTIVE: The purpose of this study was to establish baseline dialysate white blood cell (WBC) counts and differentials in noninfected rats on peritoneal dialysis (PD). DESIGN: Sixteen male Sprague-Dawley rats underwent PD in the first protocol, and eight from the 16 continued PD in the second through fourth protocols. At the beginning of the experiments, all animals had a PD catheter implanted and were initiated on PD with 1.5% dextrose dialysis solution twice daily. In the first protocol, WBC counts and differentials were assessed from day 4 to day 15 of dialysis in noninfected animals to establish "normal values" for such a rat model. In protocol 2, WBC counts and solute concentrations in small aliquots of dialysate obtained from the catheter were compared to values in well-mixed total drainage. Protocol 3 was designed to assess effects of dwell time on WBC counts. Protocol 4 examined the effect of glucose concentration of dialysis solution on WBC counts. RESULTS: In the first protocol, the mean dialysate WBC counts were significantly higher on the fourth day of dialysis, but stabilized below 2500 cells/mm3 by the eighth day. The percentage of neutrophils was stable around 20%-25%. In the second protocol, we found aliquots < 1 mL might underestimate the dialysate WBC count compared to the complete drainage. In the third protocol, WBC counts increased as cycle time became longer, but the percentage of neutrophils remained below 50%. In the fourth protocol, we did not find any effects of glucose concentration of instilled solutions on WBC counts and differentials. CONCLUSION: This study of WBC counts and differentials in noninfected rats on peritoneal dialysis establishes the range above which infection should be suspected. WBC counts increase with cycle time. Small dialysate aliquots may underestimate WBC counts. Glucose concentration does not effect WBC counts.

Animals↗
PubMed1995

Predicted and measured daily creatinine production in CAPD: identifying noncompliance.

OBJECTIVE: To evaluate the ratio of measured creatinine (Cr) production to predicted creatinine production as an index of noncompliance in patients on continuous ambulatory peritoneal dialysis (CAPD). DESIGN: A cross-sectional analysis. PATIENTS: One hundred and twenty-one patients on CAPD. MEASUREMENTS: We have calculated Cr production from measured Cr outputs in 24-hour collections of urine and dialysate. Predicted Cr productions were calculated from standard tables. Weekly KT/V urea and weekly Cr clearances were determined from the same 24-hour urine and dialysate collections. Lean body mass (LBM) was calculated from the Cr production. Serum albumin concentration was measured. RESULTS: The ratio of measured/predicted Cr production correlated positively and significantly with weekly KT/V urea, the protein equivalent of nitrogen appearance (PNA), weekly Cr clearance, and LBM. There was a decline in serum albumin concentration at ratios greater than 1.24, supporting the opinions of previous authors who have suggested that ratios greater than 1.24 are highly suggestive of noncompliance with the dialysis prescription. Defining noncompliance as a ratio greater than 1.24 implied that at least 5% of the female and 17% of the male patients were noncompliant. CONCLUSIONS: Declining serum albumin concentrations at higher ratios of measured/predicted Cr production support the opinion that this is an index of noncompliance. However, not all noncompliant patients necessarily have a ratio greater than 1.24. Weekly KT/V urea, weekly Ccr and LBM are all artifactually increased by "washout effects" if all exchanges are done only or mainly on the collection day.

Body Mass Index↗
PubMed1995

Continuous ambulatory peritoneal dialysis and the heart.

OBJECTIVE: To review clinical research pertaining to continuous ambulatory peritoneal dialysis (CAPD) and the heart. DATA SOURCES: A Medline computer search was employed to identify appropriate references from 1970 - 1994. Indexing terms were: continuous ambulatory peritoneal dialysis, hemodialysis, heart or cardiac, left ventricle, coronary artery disease, and survival. English and non-English language abstracts were scrutinized. STUDY SELECTION: Forty-six studies were reviewed and utilized. Numerical data extracted are reported in this review as they were reported in the original article. RESULTS: This review provides a broad-based survey of studies pertaining to CAPD and the heart. Most of the studies relate to CAPD and left ventricular structure or function. Little information exists concerning CAPD and coronary artery disease, valvular disease, pericardial disease, and cardiac arrhythmias. Studies pertaining to patient survival on CAPD identify coronary artery disease and congestive heart failure as major risk factors, but in-depth quantification of these cardiovascular disorders is lacking in the literature. CONCLUSIONS: CAPD is capable of decreasing left ventricular (LV) volume and improving LV systolic function in patients with LV enlargement and those with LV systolic dysfunction. The effect of CAPD on left ventricular hypertrophy (LVH) and LV diastolic function is variable. CAPD produces symptomatic improvement in patients with refractory congestive heart failure, but its effect on survival in such patients is uncertain. Atherogenic lipid abnormalities occur in CAPD patients. The clinical significance of these abnormalities is uncertain. Coronary artery bypass surgery can be performed safely and effectively on CAPD patients. CAPD is not arrhythmogenic. Survival of CAPD patients is similar to that of hemodialysis patients except in elderly diabetics for whom it is slightly lower.

Arrhythmias, Cardiac↗
PubMed1995

Preliminary evaluation of silver-coated peritoneal catheters in rats.

Silver is known to have powerful antibacterial properties against a variety of micro-organisms and has a low toxicity and a favorable biocompatibility profile. This study was designed to evaluate the effectiveness of silver-coated catheters in preventing early exit-site infection and to assess tunnel morphology. Seven male Sprague-Dawley rats underwent simultaneous implantation of two double-cuffed, silver-coated silicone rubber and standard silicone rubber catheters. Weekly observations and photographs documented exit-site characteristics. The animals were sacrificed and catheters removed and processed for histopathology of the external tunnel at 5 weeks. Exit sites of silver-coated catheters tended to have less inflammation and infection and healed better than those of uncoated catheters; however, these data did not achieve significance using the Wilcoxon signed-rank test. Sections of the external tunnel of well-healing exit sites showed an epithelialized tract with granulation tissue near the cuff and significant invasion of the external cuff by collagen with a mild neutrophilic inflammatory response. In contrast, the histology of the external tunnel of infected exists revealed exudate overlying inflammatory granulation tissue and a variable degree of fibrosis of the cuff. When the exit sites appeared similar, no significant histopathological differences in sinus tract and cuff morphology were noted with either silver or standard catheters. In conclusion, these findings suggest that silver coating of catheters may decrease the incidence of early exit-site infections and allow better ingrowth of the catheter.

Animals↗