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Biomedical subjects

G D Jay

Publications and source records attributed to G D Jay.

At least 19 recordsLinked to original sources
PubMed2006

Frictional properties of Hartley guinea pig knees with and without proteolytic disruption of the articular surfaces.

OBJECTIVE: To apply a pendulum technique to detect changes in the coefficient of friction of the articular cartilage of the intact guinea pig tibiofemoral joint after proteolytic disruption. DESIGN: Twenty-two hind limbs were obtained from 11 3-month old Hartley guinea pigs. Twenty knees were block-randomized to one of two treatment groups receiving injections of: (1) alpha-chymotrypsin (to disrupt the superficial layer of the articular surface) or (2) saline (sham; to control for the effects of the intra-articular injection). The legs were mounted in a pendulum where the knee served as the fulcrum. The decay in pendulum amplitude as a function of oscillation number was first recorded and the coefficient of friction of the joint was determined from these data before injection. Ten microliters of either isotonic saline or 1 Unit/microL alpha-chymotrypsin was then injected into the intra-articular joint space and incubated for 2h. The pendulum test was repeated. Changes in the coefficient of friction between the sham and alpha-chymotrypsin joints were compared. One additional pair of knees was used for histological study of the effects of the injections. RESULTS: Treatment with alpha-chymotrypsin significantly increased the coefficient of friction of the guinea pig knee by 74% while sham treatment decreased it by 8%. Histological sections using Gomori trichrome stain verified that the lamina splendens was damaged following treatment with alpha-chymotrypsin and not following saline treatment. CONCLUSIONS: Treatment with alpha-chymotrypsin induces mild cartilage surface damage and increases the coefficient of friction in the Hartley guinea pig knee.

Animals↗
PubMed2005

Association of articular cartilage degradation and loss of boundary-lubricating ability of synovial fluid following injury and inflammatory arthritis.

OBJECTIVE: To study the relationship between the boundary-lubricating ability of synovial fluid (SF) and articular cartilage damage in a rabbit knee injury model, to correlate collagen markers of such damage with SF boundary-lubricating ability and elastase activity, and to examine the lubricating ability of SF, together with collagen markers of articular cartilage damage, under the inflammatory conditions of knee joint synovitis (KJS) and rheumatoid arthritis (RA). METHODS: SF was aspirated weekly from the affected knee joints of 10 adult rabbits following transection of the anterior and posterior cruciate ligaments. The boundary-lubricating ability of SF was determined in vitro using a previously described friction apparatus. Lubricin concentrations and type II collagen (CII) peptides were quantified by sandwich enzyme-linked immunosorbent assays (ELISAs). Levels of the C-terminal neoepitope 9A4 (derived from collagenase degradation of CI, CII, and CIII) and of epitope 5-D-4 of keratan sulfate (a marker of proteoglycan depletion) were quantified by inhibition ELISAs. Elastase activity was measured spectrophotometrically. The sensitivity of purified human lubricin to digestion by neutrophil elastase (NE) was examined by Western blotting. RESULTS: The lubricating ability of SF from injured rabbit knees was significantly decreased at weeks 2 and 3 compared with week 1 after injury. Lubricin concentrations were significantly higher at week 1 than at weeks 2 and 3. CII peptide concentrations increased significantly at weeks 2 and 3 compared with week 1, while 9A4 neoepitope concentrations increased significantly at week 3 compared with weeks 1 and 2. There were no significant differences in epitope 5-D-4 concentrations among the 3 weeks. Elastase activity in SF increased significantly at weeks 2 and 3 compared with week 1. Elastase activity correlated significantly with diminishing lubrication at weeks 1, 2, and 3. SF from patients with KJS or RA exhibited deficient lubrication and elevated levels of CII peptides compared with SF from normal controls. NE was shown to completely degrade purified human lubricin in vitro. CONCLUSION: Loss of boundary-lubricating ability of SF after injury is associated with damage to the articular cartilage matrix. This can be attributed to inflammatory processes resulting from the injury, particularly in the early phases. This association also exists in patients with acute knee injuries or progressive chronic inflammatory arthritis.

Animals↗
PubMed2004

Simulation based teamwork training for emergency department staff: does it improve clinical team performance when added to an existing didactic teamwork curriculum?

OBJECTIVE: To determine if high fidelity simulation based team training can improve clinical team performance when added to an existing didactic teamwork curriculum. SETTING: Level 1 trauma center and academic emergency medicine training program. PARTICIPANTS: Emergency department (ED) staff including nurses, technicians, emergency medicine residents, and attending physicians. INTERVENTION: ED staff who had recently received didactic training in the Emergency Team Coordination Course (ETCC) also received an 8 hour intensive experience in an ED simulator in which three scenarios of graduated difficulty were encountered. A comparison group, also ETCC trained, was assigned to work together in the ED for one 8 hour shift. Experimental and comparison teams were observed in the ED before and after the intervention. DESIGN: Single, crossover, prospective, blinded and controlled observational study. Teamwork ratings using previously validated behaviorally anchored rating scales (BARS) were completed by outside trained observers in the ED. Observers were blinded to the identification of the teams. RESULTS: There were no significant differences between experimental and comparison groups at baseline. The experimental team showed a trend towards improvement in the quality of team behavior (p = 0.07); the comparison group showed no change in team behavior during the two observation periods (p = 0.55). Members of the experimental team rated simulation based training as a useful educational method. CONCLUSION: High fidelity medical simulation appears to be a promising method for enhancing didactic teamwork training. This approach, using a number of patients, is more representative of clinical care and is therefore the proper paradigm in which to perform teamwork training. It is, however, unclear how much simulator based training must augment didactic teamwork training for clinically meaningful differences to become apparent.

Adult↗
PubMed2003

Detection of collagen type II and proteoglycans in the synovial fluids of patients diagnosed with non-infectious knee joint synovitis indicates early damage to the articular cartilage matrix.

OBJECTIVE: We have sought to determine if markers of proteoglycans and collagen type II (CII) degradation can be detected at an early stage following acute knee injury in the synovial fluid (SF) from a group of patients diagnosed with non-infectious knee joint synovitis (KJS). CII, proteoglycans and elastase activity in the SF from patients with KJS were compared to SF from patients with two chronic arthritis conditions: osteoarthritis (OA) and rheumatoid arthritis (RA) as well as normal SF controls. METHODS: CII peptides were measured by sandwich ELISA using two monoclonal antibodies: 8:6:D8, a CII-specific antibody, and 14:7:D8 which binds to an amino acid sequence on CII as well as collagens type I, III and V. Epitope 9A4, a neo-epitope resulting from collagenase digestion of CI, CII, and CIII was measured by inhibition ELISA. Proteoglycans measurement included total sulfated glycosaminoglycans (sGAG) by dye-binding assay and 5-D-4 epitope, a keratan sulfate epitope, by inhibition ELISA. Elastase activity was measured colorimetircally using N-succinyl trialanine p-nitroanilide (SANA) substrate. RESULTS: The quantified CII peptide concentrations by sandwich and inhibition ELISA were significantly higher in SF from patients with KJS (P<0.05) compared to SF from patients with OA, RA and normal aspirates. 5-D-4 and sGAG concentrations were significantly lower (P<0.05) in SF from patients with KJS compared to SF from patients with OA and RA. Elastase activity in SF from patients with KJS and RA were significantly higher (P<0.05) than SF from patients with OA. A significant correlation exists between elastase activity and 9A4 epitope concentration in SF from patients with KJS. CONCLUSION: The elevated CII peptides concentrations in KJS SF compared to normal and OA aspirates indicate early signs of cartilage network damage. The low proteoglycans concentrations in SF from patients with KJS may indicate that injury is limited to the superficial zone of cartilage in the patient population studied. The high elastase activity in SF from patients with KJS and RA are linked to the high CII peptides concentration. The elastase activity in the SF from patients with KJS is due to the action of neutrophil elastase (NE) and collagenases, where both contribute to the destruction of the articular cartilage.

Arthritis, Rheumatoid↗
PubMed2001

Homology of lubricin and superficial zone protein (SZP): products of megakaryocyte stimulating factor (MSF) gene expression by human synovial fibroblasts and articular chondrocytes localized to chromosome 1q25.

We have previously identified megakaryocyte stimulating factor (MSF) gene expression by synovial fibroblasts as the origin of lubricin in the synovial cavity. Lubricin is a mucinous glycoprotein responsible for the boundary lubrication of articular cartilage. MSF has a significant homology to vitronectin and is composed of 12 exons. RNA was purified from human synovial fibroblasts and articular chondrocytes grown in vitro from tissue explants obtained from subjects without degenerative joint disease. RT-PCR was used with multiple complimentary primer pairs spanning the central mucin expressing exon 6 of the MSF gene and individual exons on both the N- and C-terminal sides of exon 6. Exons 2, 4 and 5 appear to be variably expressed by synovial fibroblasts and articular chondrocytes. Lubricating mucin, in the form of MSF, is expressed by both chondrocytes and synovial fibroblasts in vitro. Both lubricin and superficial zone protein (SZP), a related proteoglycan, share a similar primary structure but could differ in post-translational modifications with O-linked oligosaccharides which are predominant in lubricin and with limited amounts chondroitin and keratan sulfate found in SZP. Since most of the MSF exons are involved in the expression of lubricating mucin, a strong homology to vitronectin persists. It is therefore appropriate to consider that both SZP and lubricin occupy a new class of biomolecules termed tribonectins. Screening of a human genome bacterial artificial chromsome (BAC) library with a cDNA primer pair complimentary for exon 6 identified two clones. Both clones were complimentary for chromosome 1q25 by in situ hybridization. This same locus was previously implicated in camptodactyl-arthropathy-pericarditis syndrome (CAP) by genetic mapping. It is hypothesized that CAP, a large joint arthropathy, may be associated with ineffective boundary lubrication provided by synovial fluid.

Alternative Splicing↗
PubMed2001

Boundary lubrication by lubricin is mediated by O-linked beta(1-3)Gal-GalNAc oligosaccharides.

Lubrication of mammalian joints is mediated by lubricin, a product of megakaryocyte stimulating factor gene (MSF; GenBank accession #U70136) expression. Lubricin (M(r) approximately 240 kDa) is a mucinous glycoprotein which is 50% (w/w) post-translationally modified with beta(1-3)Gal-GalNAc incompletely capped with NeuAc, and lubricates apposed cartilaginous surfaces in the boundary mode through an unknown mechanism. Both bovine and human lubricin were purified from synovial fluid and digested with recombinant glycosidases. Released oligosaccharides were identified and quantified by fluorophore assisted carbohydrate electrophoresis (FACE). Corresponding digests of human lubricin were also assayed in a friction apparatus oscillating latex rubber against polished glass at a pressure of 0.35 x 10(6) N/m(2) and the coefficient of friction (mu) was measured. Digestion with alpha2,3-neuraminidase decreased lubricating ability by 19.3%. Partial removal of beta(1-3)Gal-GalNAc moieties by endo-alpha-N-acetyl-D-galactosaminidase reduced lubricating ability by 77.2%. Human lubricin digested with combined alpha2,3-neuraminidase and beta1-3,6-galactosidase continued to lubricate at 52.2% of its nominal value. Both bovine and human lubricin released 48.6% and 54.4% of total beta(1-3)Gal-GalNAc sidechains following digestion with endo-alpha-N-acetyl-D-galactosaminidase. Biological boundary lubrication by synovial fluid in vitro is provided primarily by extensive O-linked beta(1-3)Gal-GalNAc.

Acetylgalactosamine↗
PubMed2000

Analysis of physician ability in the measurement of pulsus paradoxus by sphygmomanometry.

CONTEXT: Measurement of pulsus paradoxus (PP) is one of several measures previously advocated in the National Heart, Lung, and Blood Institute asthma management guidelines: a pulsus of > 12 mm Hg warranted hospital admission. It is one of only a few measures that is not effort dependent and therefore important in the evaluation of patients with asthma. OBJECTIVE: Determination of physician accuracy in measuring PP. DESIGN: A model of induced PP in a trained healthy subject without respiratory disease was constructed with a fixed inspiratory resistance with measurement of inspiratory air pressure and beat-to-beat BP noninvasively. SETTING: Laboratory. PARTICIPANTS: Attending physicians from emergency medicine and critical care disciplines who served as consecutive examiners of the trained reference subject generating known PP. INTERVENTIONS: A total of 19 attending physicians were assessed for ability in measuring PP by sphygmomanometry and by palpation. The reference subject generated 4 degrees of PP sequentially, with each examiner blinded to the value of negative inspiratory pressure and PP. Examiners first assessed PP qualitatively by palpation, followed by its measurement within 2 min. MAIN OUTCOME MEASURE: Proximity of physician-measured PP (PPm) to true PP (PPt). RESULTS: At inspiratory pressures of - 10, - 15, - 20, and - 25 mm Hg, PPt was 13.7, 16.2, 19.1, and 20.7 mm Hg, respectively (F = 14.8, p < 0. 0001; analysis of variance [ANOVA]). At the same pressures, PPm was 13.1, 17.5, 17.7, and 18.0 mm Hg (p > 0.10; ANOVA). Linear regression of PPm against PPt for each examiner revealed a slope (SE) of 0.53 (0.23), and not a 1:1 relationship. CONCLUSIONS: Past and present guidelines do not account for the challenges in measuring PP, especially in tachypneic patients. Sphygmomanometric determination of PP should be augmented by new aids developed through technological innovation.

Adult↗
PubMed2000

Lubricin is a product of megakaryocyte stimulating factor gene expression by human synovial fibroblasts.

OBJECTIVE: The boundary lubricating ability of human synovial fluid has been attributed to lubricin, a mucinous glycoprotein. We investigated the primary structure of lubricin and its cellular origin. METHODS: Lubricin was purified from pooled synovial fluid aliquots with normal lubricating activity obtained from patients with osteoarthritis. Lubricating ability of lubricin was assayed in a friction apparatus that oscillates natural latex against a ring of polished glass. Native and lubricin deglycosylated with O-glycosidase DS and NANase III were trypsinized and sequenced by liquid chromatography mass spectrometry. Sequence results were compared to known structures in GenBank. Sequence data from strong matches were used in creating cDNA primers for reverse transcription-polymerase chain reaction (RT-PCR) with RNA from human synovial fibroblasts obtained intraoperatively. RESULTS: Purified lubricin possesses an apparent molecular weight of 280 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Deglycosylation decreased the apparent molecular weight on SDS-PAGE to 120 kDa. Sequences specific for megakaryocyte stimulating factor precursor (MSF) were identified in GenBank. A 100% match was observed for exons 6 though 9 of MSF. Lubricin/MSF reduced the coefficient of friction (m) in the latex:glass bearing from 0.131 to 0.047. MSF is 1404 amino acids in size with multiple functional domains similar to vitronectin. The reported structure of MSF contains a centrally located mucin (exon 6) with 76 repeats of the degenerate motif of KEPAPTT, the presumed site of extensive O-linked glycosylation. RT-PCR with primers complementary for Pro214- Ala307 in exon 6 and RNA from human synovial fibroblasts produced the predicted product size of 280 bp. CONCLUSION: Lubricin is secreted by synovial fibroblasts via expression of the MSF gene. Lubricin is constructed of MSF exons 6 through 9 but the presence of other exons cannot be excluded. Lubricin/MSF is the only lubricating component in the final lubricating fraction of human synovial fluid.

Amino Acid Sequence↗
PubMed1999

The potential for improved teamwork to reduce medical errors in the emergency department. The MedTeams Research Consortium.

This article describes emergency department care work teams designed to improve team communication and coordination and reduce error. The core of this teamwork system is the teaching of teamwork behaviors and skills, development of teamwork habits, and creation of small work teams, all of which are key teamwork concepts largely drawn from successful aviation programs. Arguments for enculturating teamwork into ED practice are drawn from a retrospective study of ED malpractice incidents. Fifty-four incidents (1985-1996), a sample of convenience drawn from 8 hospitals, were identified and judged mitigable or preventable by better teamwork. An average of 8.8 teamwork failures occurred per case. More than half of the deaths and permanent disabilities that occurred were judged avoidable. Better teamwork could save nearly $3.50 per ED patient visit. Caregivers must improve teamwork skills to reduce errors, improve care quality, and reduce litigation risks.

Communication↗
PubMed1999

The effect of phospholipase digestion upon the boundary lubricating ability of synovial fluid.

OBJECTIVE: To identify the boundary lubricant in synovial fluid (SF). Is synovial lubrication mediated by surface active phospholipid as opposed to mucinous glycoprotein? METHODS: A sonicated preparation of phosphatidylcholine and bovine SF were tested in vitro in a bearing of latex oscillating against polished glass under a load of 0.35 x 10(6) N/m2. The friction apparatus isolates conditions of boundary lubrication and has been validated against a cartilaginous bearing. Coefficient of friction (mu) was measured and compared against mu from physiologic saline, which served as a control. Separate digestions were carried out upon the SF with trypsin, phospholipase C, and phospholipase A2 in the presence and absence of proteolytic inhibitors. RESULTS: Digestions of bovine SF by phospholipase C in the presence of protease inhibitors did not remove boundary lubricating ability compared to an undigested control (p = 0.89). Digestion of bovine SF with trypsin removed all lubricating ability and raised friction (p = 0.004). Commercial purified phospholipase C contained trypsin-like activity when activity was tested with N alpha-benzoyl-L-arginine ethyl ester as substrate. Similar results were observed for phospholipase A2, which possesses a lower amount of trypsin activity. CONCLUSION: The results indicate that phospholipid does not play a prominent role in synovial fluid's ability to lubricate an artificial bearing. Rather, the boundary lubricating ability of SF is attributable to lubricin, a mucinous glycoprotein.

Animals↗
PubMed1998

Comparison of the boundary-lubricating ability of bovine synovial fluid, lubricin, and Healon.

Purified human umbilical hyaluronate and a commercial preparation of rooster comb hyaluronate (Healon) intended for intra-articular viscosupplementation did not demonstrate the same degree of boundary-lubricating ability as bovine synovial fluid or its purified lubricating mucin, lubricin (p < 0.01). Boundary lubrication was measured in vitro in an arthrotripsometer oscillating natural latex against polished glass under a load of 0.35 MPa with an entraining velocity of 0.37 mm/s. The two hyaluronate solutions possessed the same hyaluronate concentration as synovial fluid, but Healon was 4.5 times more viscous. Present practice of viscosupplementation therapy for degenerative joint disease is limited and fails to implicate the important role of synovial mucin. Boundary lubrication provided by synovial mucin, independent of its viscosity, is not replicated by hyaluronate hydrogels.

Animals↗
PubMed1998

Pulsus paradoxus: an objective measure of severity in croup.

We used a noninvasive monitor of arterial pressure to determine the utility of pulsus paradoxus (PP) as an objective severity measure in croup. We performed a prospective, blinded comparison of PP in children with croup versus healthy control subjects, analyzed the relationship between PP and Westley croup score (WCS), and observed the effect of racemic epinephrine (RE) on PP and WCS in a subgroup of patients with severe croup. The PP and WCS were measured at presentation and in severe patients after treatment with RE. Mean PP was 6.1 +/- 1.8 (SD) mm Hg (n = 29) in control subjects compared with a mean of 17.8 +/- 11.2 (SD) mm Hg (n = 28) in patients with croup (p < 0.00001). There was significant concordance between baseline WCS and PP (Spearman's rho: 0.68; p = 0.0001). The mean decrease in PP after RE was 7.5 +/- 11.8 (SD) mm Hg (p = 0.05; n = 12). The magnitude of decrease in PP after RE has significant concordance with the concurrent decrease in WCS (Spearman's rho: 0.73; p < 0.007). PP is elevated in children with croup, and the magnitude of elevation correlates with severity as measured by the WCS. PP may have utility as a research tool to objectively measure the severity of upper airway obstruction in croup.

Adolescent↗
PubMed1997

Factors and methodology in achieving ideal delivery temperatures for intravenous and lavage fluid in hypothermia.

A study was undertaken to determine the relationship between temperature and delivery rate of warmed intravenous fluid using standard intravenous infusion equipment and tubing. One-liter bags of 0.9% NaCl were warmed to 60 degrees C and run through standard microdrip tubing for 1 hour at rates of 1,000, 800, 600, and 400 mL/h. Thermistor probes were placed into the bag and into the tubing at 0, 100, 180, 230, and 280 cm from the intravenous bag. Separate fluid bags were also warmed to 39.3 degrees and 75 degrees C, and the fluid was run through the same apparatus at 1,000 mL/h and 200 mL/h, respectively. Temperatures were recorded at each site at the start of the infusion and every 10 minutes thereafter for 1 hour, Subsequently, 60-mL syringes of fluid warmed to 39.5 degrees C were eluted through 50 cm tubing over 10 minutes at 300 mL/h and 360 mL/h. Mean delivery temperature over each 10-minute infusion was determined. Fluid preheated to 39.3 degrees C approached room temperature at delivery even at a flow rate of 1,000 mL/h and tubing lengths as short as 100 cm. Fluid preheated to 60 degrees C was delivered at near 37 degrees C using tubing lengths as long as 280 cm when eluted at 1,000 mL/h. Fluid preheated to 39 degrees C in 60-mL syringes and eluted through 50 cm of tubing over a period of 10 minutes at 300 mL/h or 360 mL/h was delivered near a mean temperature of 37 degrees C. These results show that warmed fluid can be delivered through standard intravenous tubing at or near 37 degrees C if the fluid is preheated to 60 degrees C and eluted through long tubing (280 cm) at high flow rates (1,000 mL/h). Alternatively, fluid warmed to 37 degrees C to 42 degrees C can be delivered at or near 37 degrees C via intermittent bolus through short tubing (50 cm) either by hand or syringe pump. The latter approach would be particularly beneficial in the pediatric population, in whom it is not advisable to administer fluid at flow rates as high as 1,000 mL/h.

Adult↗
PubMed1997

Randomized, prospective trial of bilevel versus continuous positive airway pressure in acute pulmonary edema.

OBJECTIVE: To evaluate whether bilevel positive airway pressure, by actively assisting inhalation, more rapidly improves ventilation, acidemia, and dyspnea than continuous positive airway pressure (CPAP) in patients with acute pulmonary edema. DESIGN: Randomized, controlled, double-blind trial. SETTING: Emergency department in a university hospital. PATIENTS: Twenty-seven patients, presenting with acute pulmonary edema, characterized by dyspnea, tachypnea, tachycardia, accessory muscle use, bilateral rales, and typical findings of congestion on a chest radiograph. INTERVENTIONS: In addition to standard therapy, 13 patients were randomized to receive nasal CPAP (10 cm H2O), and 14 patients were randomized to receive nasal bilevel positive airway pressure (inspiratory and expiratory positive airway pressures of 15 and 5 cm H2O, respectively) in the spontaneous/timed mode that combines patient flow-triggering and backup time-triggering. MEASUREMENTS AND MAIN RESULTS: After 30 mins, significant reductions in breathing frequency (32 +/- 4 to 26 +/- 5 breaths/min), heart rate (110 +/- 21 to 97 +/- 20 beats/min), blood pressure (mean 117 +/- 28 to 92 +/- 18 mm Hg), and Paco2 (56 +/- 15 to 43 +/- 9 torr [7.5 +/- 2 to 5.7 +/- 1.2 kPa]) were observed in the bilevel positive airway pressure group, as were significant improvements in arterial pH and dyspnea scores (p < .05 for all of these parameters). Only breathing frequency improved significantly in the CPAP group (32 +/- 4 to 28 +/- 5 breaths/min, p < .05). At 30 mins; the bilevel positive airway pressure group had greater reductions in Paco2 (p = .057), systolic blood pressure (p = .005), and mean arterial pressure (p = .03) than the CPAP group. The myocardial infarction rate was higher in the bilevel positive airway pressure group (71%) compared with both the CPAP group (31%) and historically matched controls (38%) (p = .05). Duration of ventilator use, intensive care unit and hospital stays, and intubation and mortality rates were similar between the two groups. CONCLUSIONS: Bilevel positive airway pressure improves ventilation and vital signs more rapidly than CPAP in patients with acute pulmonary edema. The higher rate of myocardial infarctions associated with the use of bilevel positive airway pressure highlights the need for further studies to clarify its effects on hemodynamics and infarction rates, and to determine optimal pressure settings.

Acute Disease↗
PubMed1997

Evaluation of pre- and posttreatment pulse oximetry in acute childhood asthma.

OBJECTIVE: To evaluate the utility of pre- and posttreatment O2 saturation (SpO2) for prediction of admission or relapse after ED release in acute asthma exacerbations using a standardized treatment protocol. DESIGN: A prospective, double-blind, observational study was performed at a pediatric ED. Children with acute asthma were enrolled upon ED presentation. SpO2 was measured prior to treatment and after disposition decision. Two experienced physicians determined disposition based on history and physical examination alone, while blinded to SpO2. Relapse of released patients was determined by telephone follow-up. RESULTS: A pretreatment room-air SpO2 of < or = 91% had a sensitivity of 0.24, a specificity of 0.86, and a likelihood ratio of 1.77 to predict admission/relapse. A posttreatment room-air SpO2 of < or = 91% had a sensitivity of 0.34, a specificity of 0.98, and a likelihood ratio of 16.43 to predict admission/relapse. CONCLUSIONS: As opposed to some previous studies, this study found pretreatment SpO2 to be a relatively poor predictor of admission. A posttreatment SpO2 of < or = 91% occurred in a minority (32%) of patients, but increased the odds of admission 16-fold and may be used as an adjunct to objectively confirm the need for admission.

Adolescent↗
PubMed1997

Alterations in pharmacokinetics of carboxyhemoglobin produced by oxygen under pressure.

The pharmacokinetic effect of elevated oxygen partial pressures in the elimination of carboxyhemoglobin (COHb) by O2 administration was studied in an inflatable hyperbaric chamber. A double crossover prospective analysis between the modified Gamow bag and non-rebreather (NRB) mask O2 was conducted among 12 healthy, adult volunteers who smoked five cigarettes sequentially within a 60-min period. COHb levels were measured using co-oximetry before and after smoking. Subjects inspired hyperbaric oxygen (HBO2) and normobaric oxygen (NBO2) in separate trials for 40 min. Mean COHb levels (1.16 +/- 0.28 g/dl) post-smoking were representative of low-level poisoning. NBO2 consisted of a NRB mask at a rate of 15 liter/min outside the Gamow bag. HBO2 was delivered inside the Gamow bag with a demand valve regulator mask at a Po2 of 1.58 atm abs. A significant increase in the half-life (t 1/2) of COHb was observed for each subject in the Gamow bag (P < 0.05; repeated measures analysis of variance). Average t 1/2 for COHb was 26.3 +/- 3.7 min (n = 12) and 71.3 +/- 9.9 min (n = 12) while breathing HBO2 and NBO2, respectively. Pharmacokinetic modeling was performed using PCNONLIN software for each subject. Both zero and first order elimination kinetics were tested and the model of best fit determined using the Akaike Information Criterion for each subject. A significant shift in COHb elimination from a zero to first order mechanism with elevation in O2 partial pressure was observed (P = 0.002; McNemar's test). HBO2 provides a pharmacokinetic advantage over NRB mask O2 in eliminating mild carboxyhemoglobinemia.

Adult↗