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S Friberg

Publications and source records attributed to S Friberg.

At least 19 recordsLinked to original sources
PubMed2005

Aerobiology in the operating room and its implications for working standards.

Two novel operating room (OR) ventilation concepts, i.e. the upward displacement or thermal convection system and the exponential ultra-clean laminar air flow (LAF) designed to function without extra walls, were evaluated from a bacteriological point of view. The thermal convection system (17 air changes/h) was compared with conventional ventilation (16 air changes/h) with an air inlet at the ceiling and evacuation at floor level. The exponential LAF was compared with the vertical ultra-clean LAF and the horizontal ultra-clean LAF, both with extra side walls. The comparison was made using strictly standardized simulated operations and, except for the horizontal LAF, it was performed in the same OR where the type of ventilation was changed. In the different areas important for surgical asepsis, the thermal system resulted in a twofold to threefold increase in bacterial air and surface counts compared to the conventional system (statistical significance = p < 0.05-0.0001). The bacteriological efficiency of the exponential LAF was equal to the horizontal and vertical LAF units with extra walls in the OR, and all three systems easily fulfilled the criteria for ultra-clean air, i.e. bacteria-carrying particles < 10/m3. In the areas important for surgical asepsis the turbulent ventilation systems yielded highly significant correlation between air and surface contamination (p < 0.02-0.0006). No such correlation existed in the LAF systems.

Air Microbiology↗
PubMed2003

The addition of a mobile ultra-clean exponential laminar airflow screen to conventional operating room ventilation reduces bacterial contamination to operating box levels.

A mobile screen producing ultra-clean exponential laminar airflow (LAF) was investigated as an addition to conventional turbulent/mixing operating room (OR) ventilation (16 air changes/h). The evaluation was performed in a small OR (50 m(3)) during 60 standardized operations for groin hernia including mesh implantation. The additional ventilation was used in 50 of the operations. The LAF passed from the foot-end of the OR table over the instrument and surgical area. Strict hygiene OR procedures including tightly woven and non-woven OR clothing were used. Sedimentation rates were recorded at the level of the patients' chests (N=60) (i.e. the air had passed the surgical team) and in the periphery of the OR. In addition bacterial air contamination was studied above the patients' chests in all 10 operations without the additional LAF and in 12 with the LAF. The screen reduced the mean counts of sedimenting bacteria (cfu/m(2)/h) on the patients' chests from 775 without the screen to 355 (P=0.0003). The screen also reduced the mean air counts of bacteria (cfu/m(3)) above the patients' chests from 27 to 9 (P=0.0001). No significant differences in mean sedimentation rates (cfu/m(2)/h) existed in the periphery of the OR where 628 without and 574 with screen were recorded. During the follow-up period of six months no surgical site infections were detected. In conclusion when the mobile LAF screen was added to conventional OR ventilation the counts of aerobic airborne and sedimenting bacteria-carrying particles downstream of the surgical team were reduced to the levels achieved with complete ultra-clean LAF OR ventilation (operating box).

Bacteria↗
PubMed2002

Mobile zoned/exponential LAF screen: a new concept in ultra-clean air technology for additional operating room ventilation.

A mobile screen (0.5 x 0.4 m) producing ultra-clean exponential LAF (air-flow central zone 0.6 m/s and peripheral zone 0.4 m/s) was investigated as an addition to conventional turbulent/mixing operating room ventilation. The evaluation was performed during strictly standardized sham operations reflecting conditions during major surgery. The study consisted of a pilot experiment designed to give high counts of sedimenting aerobic colony forming units (cfu). In a second main study, recording dust particles, air-borne and sedimenting aerobic cfu, the screen was associated with optimal operating room clothing. In the pilot experiment the use of the screen resulted in a substantial reduction of sedimenting bacteria from 3835-4940 to 0-390 cfu/m(2)/h. In the main study, the use of the additional LAF reduced the surface contamination from 416-329 to 7-78 cfu/m(2)/h up to 1.6 m from the screen (P=0.001-0.0001). Measured in the wound area the screen reduced the air counts of bacteria from 9-14 to 0.2-0.4 cfu/m(3) (P=0.008-0.0001) and a marked reduction of air-borne dust particles was recorded (P=0.007-0.009). In conclusion, the additional mobile LAF screen reduced the counts of aerobic air-borne and sedimenting bacteria-carrying particles as well as dust particles to the levels gained with complete ultra-clean LAF room ventilation. Thus, the screen might prove a valuable addition to operating room ventilation as well as in other areas where asepsis is essential.

Air Microbiology↗
PubMed2001

Surgical area contamination--comparable bacterial counts using disposable head and mask and helmet aspirator system, but dramatic increase upon omission of head-gear: an experimental study in horizontal laminar air-flow.

The effect of different head coverings on air-borne transmission of bacteria and particles in the surgical area was studied during 30 strictly standardized sham operations performed in a horizontal laminar air flow (LAF) unit. The operating team members wore disposable gowns plus either a non-sterile head covering consisting of a squire type disposable hood and triple laminar face mask, a sterilized helmet aspirator system or no head cover at all. In the wound area both types of head cover resulted in low and comparable air (means of 8 and 4cfu/m(3)) and surface contamination (means of 69 and 126cfu/m(2)/h) rates. Omission of head-gear resulted in a three- to five-fold increase (P > or = 0.01- 0.001), depending on site sampled air contamination rate (mean of 22cfu/m(3)) whereas the bacterial sedimentation rate in the wound area increased about 60-fold ( P > or = 0.0001). A proper head cover minimized the emission of apparently heavy particles that were not removed by the horizontal LAF and contained mainly streptococci, presumably of respiratory tract origin. Dust particle counts revealed no differences between the three experimental situations. No correlation between air and surface contamination rates or between air contamination and air particle counts was found. We conclude that, from a bacteriological point of view, disposable hoods of squire type and face masks are equally as efficient as a helmet aspirator system and both will efficiently contain the substantial emission of bacteria-carrying droplets from the respiratory tract occurring when head cover is omitted. Finally, the use of bacterial air counts to assess surgical site surface contamination in horizontal LAF units must be seriously questioned.

Air Microbiology↗
PubMed1999

Correlation between surface and air counts of particles carrying aerobic bacteria in operating rooms with turbulent ventilation: an experimental study.

Airborne contamination with bacteria-carrying particles (cfu/m3) and their sedimentation rate (cfu/m2/h) was compared in an operating room (OR) equipped with two turbulent ventilation systems. One was a thermally based system with inlet of cool clean air at the floor level and evacuation of the air at the ceiling by convection (17 air changes/h). The other was a conventional plenum pressure system with air supply at the ceiling and evacuation at the floor level (16 air changes/h). The study was made during rigidly standardised sham operations (N = 20) performed in the same OR by the same six member team wearing non-woven disposable or cotton clothing. Airborne contamination in the wound and instrument areas was related to the surface contamination rate in the same areas and in addition, on the patient chest and in the periphery of the OR. With the exception of the periphery of the OR, the surface and air contamination rates were highly correlated in both ventilation systems (P = 0.02-0.0006, r2 = 0.52-0.79). This was also true particularly when disposable clothing was used while the correlation was weaker in cotton clothing experiments. An equation describing the relation between surface and air counts is given. Typically, the surface counts were numerically 16-fold the air counts, i.e., the number of colonies sedimenting on four 14 cm-diameter agar plates during 1 h will almost equal the number of airborne cfu per m3. We propose, that sedimentation plates represent not only a technically easier method than air sampling but when correctly used, are also the most realistic indicator of airborne bacterial OR contamination in areas critical for surgery.

Air Microbiology↗
PubMed1999

Inconsistent correlation between aerobic bacterial surface and air counts in operating rooms with ultra clean laminar air flows: proposal of a new bacteriological standard for surface contamination.

The relationship between surface contamination (cfus/m2/h) with particles carrying aerobic bacteria and corresponding air contamination rates (cfus/m3) was evaluated in operating rooms (OR) equipped with ultra clean vertical or horizontal laminar airflow (LAF). For the evaluation we collected data during strictly standardized sham operations using non-woven disposable or cotton clothing. Air contamination in the wound and instrument areas (Casella slit sampler) was related to the surface contamination rate (settle plates) in the same areas and in addition, on the patient chest. Typically, the mean surface counts were 20-70 cfus/m2/h and the air counts 1-2 cfus/m3 in disposable clothing experiments, whilst the use of cotton clothing resulted in higher counts of 100-200 cfus/m2/h (wound P > 0.05, patient P > 0.05, instruments P < 0.01) and 4 cfus/m3 (P < 0.02-0.001). In the vertical LAF, taking both disposable and cotton clothing operations together, the surface and air contamination rates (surface/air ratio SAR) were highly correlated (P = 0.02-0.004) and the ratio varied between 18:1 and 50:1 with a mean for wound air of 36:1. Using only disposable clothing in the vertical LAF, the number of significant correlations was reduced. With cotton clothing experiments in vertical LAF and in the horizontal LAF using disposable clothing, no significant correlation between surface and air contamination was found. The wide variation of SAR values and the inconsistent relationship between surface and air counts indicates that measurement of OR air contamination represents an unhelpful method for assessment of surgical site contamination in LAF units. We propose instead that colony counts on sedimentation plates is a clinically more relevant indicator of bacterial OR contamination in LAF units. In addition to the current bacteriological standard for ultra clean OR air of (< 10 cfus/m3) we suggest a corresponding standard for the surface contamination rate of < 350 cfus/m2/h.

Air Microbiology↗
PubMed1998

Zoned exponential, vertical and horizontal ultra-clean laminar airflows. No differences in bacteriological efficiency.

We compared the novel zoned exponential ultra-clean operating room ventilation, needing no extra side-walls with the traditionally used ultra-clean air systems having vertical or horizontal laminar airflow, but requiring extra side-walls. The three units were evaluated with regard to elimination of particles with focus on airborne and sedimenting bacteria-carrying particles (colony forming units, cfu) during rigidly standardized sham operations. Although minor differences were recorded inside the ultra-clean airflows, the three systems were comparable with regard to bacteriological efficiency and ensured a low air and surface contamination (0.05-4 cfu/m3 and 7-72 cfu/m2/h, depending on the site of sampling). We conclude that all three systems fulfilled well the criteria for ultra-clean air (< 10 cfu/m3), but that exponential airflow is the most versatile alternative, as additional side-walls around the operating area can be omitted.

Air Microbiology↗
PubMed1997

On the growth rates of human malignant tumors: implications for medical decision making.

Testicular carcinomas, pediatric tumors, and some mesenchymal tumors are examples of rapidly proliferating cell populations, for which the tumor volume doubling time (TVDT) can be counted in days. Cancers from the breast, prostate, and colon are frequently slow-growing, displaying a TVDT of months or years. Irrespective of their growth rates, most human tumors have been found: to start from one single cell, to have a long subclinical period, to grow at constant rates for long periods of time, to start to metastasize often even before the primary is detected, and to have metastases that often grow at approximately the same rate as the primary tumor. The recognition of basic facts in tumor cell kinetics is essential in the evaluation of important present-day strategies in oncology. Among the facts emphasized in this review are: (1) Screening programs. Most tumors are several years old when detectable by present-day diagnostic methods. This makes the term "early detection" questionable. (2) Legal trials. The importance of so-called doctor's delay is often discussed, but the prognostic value of "early" detection is overestimated. (3) Analyses of clinical trials. Such analysis may be differentiated depending on the growth rates of the type of tumor studied. Furthermore, uncritical analysis of survival data may be misleading if the TVDT is not taken into consideration. (4) Analyses of epidemiological data. If causes of malignant tumors in humans are searched for, the time of exposure must be extended far back in the subject's history. (5) Risk estimations by insurance companies. For the majority of human cancers, the 5-year survival rate is not a valid measurement for cure. Thus, basic knowledge of tumor kinetics may have important implications for political health programs, legal trials, medical science, and insurance policies.

Breast Neoplasms↗
PubMed1997

Analysis and presentation. Clinical trials on prostate cancer.

OBJECTIVE: To present guidelines for the analysis and presentation of clinical trials on prostate cancer. METHODS: Textbooks in statistics and oncology were searched for information, as were separate articles on the topic. Previously published advice was fused with own experience. RESULTS: Minimum key points are given for the sections: Introduction, Materials and Methods, Results, Discussion, and Summary. The importance of 1 primary question in any clinical trial is stressed. The value of a detailed presentation of the trial design, the patient population and the inclusion/exclusion criteria, the characterization of the disease, the treatment schedules, and toxicity is underlined. Application of various statistical methods for different endpoints is suggested. Maturity of data, time for publication, and avoidance of publication bias are discussed. Some common pitfalls in the statistical analyses of clinical results are indicated. The impact of prognostic factors, proper staging procedures, and secondary treatments on the interpretation of survival analysis is pointed out. A shift from the (mis-)use of the P value in favor of confidence intervals is strongly encouraged. The use of comparing the survival of responders versus nonresponders is to be abandoned. A few practical hints concerning the presentation are offered. The minimum of data that should be presented in absolute numbers is indicated. Also, the data that should be provided in both graphic and numeric format are exemplified. Examples of essential graphic illustrations are provided. The need for improvements in the design analysis, and presentation of clinical trials is reemphasized. Finally, numerous references are listed. The article is addressed not only to authors and readers of clinical trials, but also to editors of medical journals. CONCLUSION: The suggested guidelines may be useful in the analysis, presentation, and interpretation of clinical trials on prostate cancer. Moreover, compliance with these guidelines may facilitate comparisons with other similar trials and also, the incorporation of single studies into metaanalyses.

Clinical Trials as Topic↗
PubMed1996

Inefficiency of upward displacement operating theatre ventilation.

A new thermally based ventilation system ('Floormaster') with inlet of cool clean air at floor level, and evacuation at the ceiling of the air warmed by activity in the room (upward displacement ventilation, 17 air changes/h) was compared with a standard positive pressure (plenum) ventilation system with air supply through an inclined perforated screen along one wall at the ceiling and evacuation at floor level (conventional turbulent or mixing system, 16 air changes/h). The study was made during rigidly standardized sham operations (N = 20) performed in the same operating room by a six-member team wearing non-woven disposable or cotton clothing. In general the upward displacement system removed dust particles too small to carry bacteria (0.16-<0.3 microm, 0.001<P<0.01) more efficiently than the conventional system. However, the displacement system also yielded two to threefold higher air and surface bacterial counts in areas important for surgical asepsis (wound area, instrument table) especially with regard to bacterial sedimentation (0.001<P<0.05). The major shortcoming of the displacement system was insufficient elimination of the larger bacteria-carrying particles. The type of clothing worn by the members of the team did not influence the overall results. We conclude that an upward displacement system will lead to increased counts of airborne and sedimenting bacteria and thus increase the risk of postoperative infection in comparison with conventional operating room ventilation systems.

Air Microbiology↗
PubMed1996

Chest wall muscle cross talk in canine costal diaphragm electromyogram.

The present paper describes the influence of cross talk from the abdominal and intercostal muscles on the canine diaphragm electromyogram (EMG). The diaphragm EMG was recorded with bipolar surface electrodes placed on the costal portion of the diaphragm (abdominal side), aligned in the fiber direction, and positioned in a region with a relatively low density of motor end plates. The results indicated that cross talk may occur in the diaphragm EMG, especially during conditions of loaded breathing and light general anesthesia. The cross-talk signals showed characteristics that were entirely different from the diaphragm EMG. Although the diaphragm EMG was typical for signals recorded with electrodes aligned in the fiber direction, the cross-talk signals were characteristic of those obtained with electrode pairs not aligned in the direction of the muscle fibers. Alterations in electrode positioning, interelectrode distance, and/or electrode surface area cannot guarantee the elimination of cross-talk signals, whereas spinal anesthesia at a high thoracic level will paralyze the sources of the cross talk and hence eliminate the cross-talk signals. By taking advantage of the differences in EMG signal characteristics for the diaphragm EMG and cross-talk signals, an index that has the capability to detect cross talk was developed.

Abdominal Muscles↗
PubMed1996

Zoned vertical ultraclean operating room ventilation. A novel concept making long side walls unnecessary.

We evaluated a novel concept of High Efficiency Particulate Air (HEPA)-filtered vertical Laminar Air Flow (LAF) for operating room ventilation, designed to be used without side-walls. The LAF-unit has a central zone with an airflow of 0.4 m/s and a peripheral zone with an airflow of 0.2 m/s. The design provides an exponential downflow of air resembling an upside-down trumpet mouth and it was claimed to prevent entrainment of peripheral contaminated air. The unit was evaluated with regard to elimination of particles with focus on bacteria-carrying particles (colony-forming units = cfu) during rigidly standardized sham operations. Three different lengths of walls/enclosures (short-ending 2.0 m, medium 1.0 m and long 0.2 m above the floor) were tested. It provided a high degree of bacteriological cleanliness (0.05-4 cfu/m3 of air and 7-64 cfu/m2/h surface contamination) and its efficiency was proved to be independent of the length of the enclosures. We conclude that the novel zoned ultraclean vertical LAF unit is versatile, as it allows for omitting long side-walls, without compromising bacteriological safety.

Air Microbiology↗
PubMed1995

Prognostic value of amplification of c-erb-B2 in bladder carcinoma.

Amplification of c-erb-B2 is examined in patients with transitional cell bladder carcinoma. In a pilot study we found that the amplification correlated with high tumor grade. Tumor grade is a known prognostic factor. Therefore, we next examined the prognostic value of c-erb-B2 amplification in patients with >16 years of clinical follow-up. The gene copy number was determined, using semiquantitative PCR, in archival formalin-fixed tissues. Twenty-three percent (37/163 patients) showed the amplification. The amplification correlated with grade and stage. Moreover, we found that tumor grade (P < 0.001) and c-erb-B2 amplification (P < 0.001) showed prognostic information for survival. Patients with grade 3 tumors and concomitant c-erb-B2 amplification showed the worst prognosis. Multivariate analysis indicates that grade and c-erb-B2 amplification are independent prognostic factors.

Adult↗
PubMed1994

Describing the size of lumbar disc herniations using computed tomography. A comparison of different size index calculations and their relation to sciatica.

STUDY DESIGN: The study compared different methods to measure the absolute and relative size of lumbar disc herniations on computed tomography scans and their relation to sciatica. METHODS: Computed tomography (CT) examinations were done before and at 3 and 24 months after nonoperative treatment in 30 patients with lumbar disc herniations. The size of the herniation was described by different indexes and related to the degree of sciatica. One index was formed by the area of the herniation in relation to the spinal canal (A-index), whereas two indexes were formed by linear measurements of the herniation in relation to the spinal canal in either two (ST-index) or one direction (S-index). RESULTS: Each index was correlated significantly to the degree of sciatica. The area of the herniations decreased markedly over time. CONCLUSIONS: Linear measurements of the herniation in two perpendicular directions provide a practical and accurate way of describing the size of lumbar disc herniations.

Adult↗