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Biomedical subjects

N J Joseph

Publications and source records attributed to N J Joseph.

At least 19 recordsLinked to original sources
PubMed2002

A floating-type oral dosage form for piroxicam based on hollow polycarbonate microspheres: in vitro and in vivo evaluation in rabbits.

A floating type dosage form (FDF) of piroxicam in hollow polycarbonate (PC) microspheres capable of floating on simulated gastric and intestinal fluids was prepared by a solvent evaporation technique. Incorporation efficiencies of over 95% were achieved for the encapsulation. In vitro release of piroxicam from PC microspheres into simulated gastric fluid at 37 degree C showed no significant burst effect. The amount released increased with time for about 8 h after which very little was found to be released up to 24 h. In intestinal fluid, the release was faster and continuous and at high drug payloads, the cumulative release reached above 90% in about 8 h. In vivo evaluation of different dosage forms of piroxicam such as free drug, drug-encapsulated microspheres and microspheres along with a loading dose of free drug in rabbits showed multiple peaking in the plasma concentration-time curve suggesting enterohepatic recirculation of the drug. Pharmacokinetic analysis showed that the bioavailability from PC microspheres alone was about 1.4 times that of the free drug and it was about 4.8 times for the dosage form consisting of the microspheres plus the loading dose. The elimination half life was increased by about three times for the microsphere preparation alone and nearly about six times for the dosage form comprising of microspheres and a loading dose in comparison to the free drug. Data obtained in this study demonstrated that FDF of piroxicam in PC microspheres was capable of sustained delivery of the drug for longer periods with increased bioavailability.

Administration, Oral↗
PubMed2001

Preoxygenation with tidal volume and deep breathing techniques: the impact of duration of breathing and fresh gas flow.

UNLABELLED: Various techniques of "preoxygenation" before anesthetic induction have been advocated, including tidal volume breathing (TVB) for 3-5 min, four deep breaths (DB) in 0.5 min, and eight DB in 1 min. However, no study has compared the effectiveness of these techniques, assessed extending deep breathing beyond 1 min, or investigated the influence of fresh gas flow (FGF) in the same subjects using a circle absorber system. In 24 healthy adult volunteers breathing oxygen from a circle absorber system by tight-fitting mask, we compared TVB/5 min and deep breathing at a rate of 4 DB/0.5 min for 2 min at 5, 7, and 10 L/min FGF. Inspired and end-tidal respiratory gases were measured at 0.5-min intervals. During TVB, end-tidal oxygen (ETO2) increased rapidly and plateaued by 2.5 min at 86%, 88%, and 88% with 5, 7 and 10 L/min FGF, respectively. ETO2 values of > or =90% were attained between 3 and 4 min. Four DB/0.5 min increased ETO2 to 75%, 77%, and 80% at 5, 7, and 10 L/min FGF. Eight DB/min resulted in ETO2 values of 82% and 87% at 7 and 10 L/min, respectively. Extending deep breathing to 1.5 and 2 min with 10 L/min FGF increased ETO2 by > or =90%, although a decrease in ETCo(2) was noted. We concluded that TVB/3-5 min was effective in achieving maximal "preoxygenation" whereas 4 DB/0.5 min resulted in submaximal "preoxygenation," and thus should be used only when time is limited. Increasing FGF from 5 to 10 L/min does not enhance "preoxygenation" with either TVB or 4 DB/0.5 min. Deep breathing yields maximal "preoxygenation" when extended to 1.5 or 2 min, and only when high (10 L/min) FGF is used. IMPLICATIONS: Using a circle absorber system, normal breathing of oxygen for 3-5 min achieves optimal oxygenation of the lungs; whereas 4 deep breaths in 30 s does not. However, extending deep breathing to 1.5-2 min and using a high flow of oxygen improves oxygenation of the lungs to the same degree as normal breathing for 3-5 min. This may have important implications for patient safety.

Adult↗
PubMed2000

Efficacy of preoxygenation with tidal volume breathing. Comparison of breathing systems.

BACKGROUND: Preoxygenation before tracheal intubation is intended to increase oxygen reserves and delay the onset of hypoxemia during apnea. Various systems are used for preoxygenation. Designed specifically for preoxygenation, the NasOral system uses a small nasal mask for inspiration and a mouthpiece for exhalation. One-way valves in the nasal mask and the mouthpiece ensure unidirectional flow. This investigation compares the efficacy of preoxygenation using the standard circle system with the NasOral system and five different resuscitation bags. METHODS: Twenty consenting, healthy volunteers were studied in the supine position for 5-min periods of tidal volume breathing using the circle absorber system, the NasOral system, and five resuscitation bags in a randomized order. Data were collected during room air breathing and at 30-s intervals during 5 min of oxygen administration. Inspired oxygen, end-tidal oxygen, and end-tidal nitrogen were measured by mass spectrometry. RESULTS: At 2. 5 min of oxygenation, end-tidal oxygen plateaued at 88.1 +/- 4.8 and 89.3 +/- 6.4% (mean +/- SD) for the circle absorber and NasOral systems, respectively. This was associated with inverse decreases in end-tidal nitrogen. At no time did these end-tidal oxygen or nitrogen values differ from each other. Three of the resuscitation bags (one disk type and two duck-bill type with one-way exhalation valves) delivered inspired oxygen more than 90%, and the end-tidal oxygen plateaued between 77 and 89% at 2 min of tidal volume breathing. The other two resuscitation bags (both duck-bill bags without exhalation valves) delivered inspired oxygen less than 40%, and the end-tidal oxygen values ranged between 21.8 +/- 5.0 and 31.9 +/- 8.7%. CONCLUSIONS: The circle absorber and NasOral systems were equally effective in achieving maximal preoxygenation during tidal volume breathing. Resuscitation bags differed markedly in effectiveness during preoxygenation; those with duck-bill valves without one-way exhalation valves were the least effective. Thus, the use of these bags should be avoided for preoxygenation.

Adult↗
PubMed1999

Usefulness of certain red blood cell indices in diagnosing and differentiating thalassemia trait from iron-deficiency anemia.

Iron-deficiency anemia and thalassemia are among the most common microcytic anemias. Differentiating these anemias by means of hemogrant indices is imprecise. Powerful statistical computer programming now enables sensitive discriminant analyses to aid in the diagnosis. Laboratory results from 383 adults were examined retrospectively and grouped according to their original diagnoses: normal (n = 78); beta-thalassemia (n = 134); alpha-thalassemia (n = 106); and iron-deficiency anemia (n = 65). Statistical analysis of results evaluated only RBC indices: RBC count, hemoglobin level, mean corpuscular volume, mean corpuscular hemoglobin, and RBC distribution width. Stepwise multivariate discriminant analysis determined those indices that best differentiated the 4 groups. The Fisher linear discriminant function for each group was calculated and tested casewise. Discriminant analysis identified mean corpuscular hemoglobin, RBC count, mean corpuscular volume, and RBC distribution width as the best set of indices for differentiating the 4 diagnoses. Casewise testing of the calculated Fisher linear discriminant function resulted in mean-weighted sensitivity of 80.4%. The present study demonstrates that a set of linear discriminant functions based on routine hemogram data can effectively differentiate between alpha-thalassemia, beta-thalassemia, and iron-deficiency anemia, with a high degree of accuracy.

Anemia, Iron-Deficiency↗
PubMed1997

Efficacy of the self-inflating bulb in differentiating esophageal from tracheal intubation in the parturient undergoing cesarean section.

We studied the efficacy of the self-inflating bulb (SIB) in differentiating tracheal from esophageal intubation in 40 parturients undergoing elective cesarean section under general anesthesia. After induction and muscle relaxation, the trachea was intubated under direct vision with cuffed tube. In 20 parturients, the esophagus was also intubated with an identical tube. Before ventilation was initiated, an independent anesthesiologist checked tube positions with the SIB using two techniques. In one technique (T1), the SIB was compressed before connection to the tube; in the other technique (T2), the SIB was first connected to the tube and then compressed. The speed of reinflation was graded as rapid, delayed, and none. Tracheal tube position was reassessed immediately before and after delivery. Before initiation of controlled ventilation, the incidence of false negative results was 47.5% with T1 and 27.5% with T2 but significantly decreased to 17.5% with T1 and 7.5% with T2 when retested before delivery. After delivery, no false negative results occurred. The incidence of false positive results immediately after induction was 30% with T1 and 35% with T2. The mechanism of false negative responses may be attributed to decreased functional residual capacity leading to reduced caliber of intrathoracic airways and terminal airway closure; whereas false positive responses may be related to an incompetent gastroesophageal junction. We conclude that the SIB is unreliable for differentiating tracheal from esophageal intubation in the parturient undergoing cesarean section.

Adult↗
PubMed1995

Effectiveness of the self-inflating bulb for verification of proper placement of the Esophageal Tracheal Combitube.

The esophageal tracheal Combitube (ETC; Sheridan Catheter Corporation, Argyle, NY) is a twin-lumen tube used to establish emergency ventilation. After blind placement, ventilation is performed via the proximal lumen if it is in the esophagus or via the distal lumen if it is in the trachea. This investigation was designed to test the reliability of the self-inflating bulb (SIB) in identifying the location of the ETC and facilitating its proper positioning in anesthetized patients. In Group 1 (n = 26), the ETC was introduced blindly. In Group 2 (n = 20), the tube was placed in the trachea (eight patients) or once in the trachea and once in the esophagus, randomly (12 patients) under direct vision rigid laryngoscopy by the anesthesiologist performing the intubation. In both groups, the efficacy of the SIB in identifying the location of the ETC was tested by a second blinded anesthesiologist. In Group 1, blind insertion of the ETC resulted in esophageal placement in all patients, and in each case was correctly identified. The second anesthesiologist reported no reinflation when the compressed SIB was connected to the distal lumen. When the compressed SIB was connected to the proximal lumen, instantaneous reinflation was observed in 23 patients, delayed reinflation (2-4 s) in two and no reinflation (> 4 s) in one patient. Instantaneous reinflation occurred in these three patients after repositioning of the ETC. In Group 2, the second anesthesiologist correctly identified the location of the ETC in all cases. The results confirm previous findings that blind introduction of the ETC leads to esophageal placement and yields adequate ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Preoperative pregnancy testing in ambulatory surgery. Incidence and impact of positive results.

BACKGROUND: The incidence of unrecognized early pregnancy and its influence on the surgical and anesthetic course in patients presenting for elective ambulatory surgery have not been previously determined. The current study was designed to determine the incidence of unrecognized pregnancy in women presenting for ambulatory surgery. In addition, it examined how discovery of the pregnancy altered the anesthetic or surgical course. METHODS: In a prospective study over a 1-yr period, all women of childbearing potential (defined as menstruating women without prior hysterectomy or tubal ligation) were preoperatively evaluated and tested for urine or serum human chorionic gonadotropin, to determine unrecognized pregnancy. If a pregnancy was detected, the disposition of the surgical procedure and the effect on the surgical and anesthetic management was recorded. RESULTS: Of 2,056 women of childbearing potential presenting for ambulatory surgery, testing revealed 7 previously unrecognized pregnancies, an incidence of 0.3%. Included among these patients were two patients scheduled to undergo fertility procedures. On learning the test result and even before being advised of available options, all patients elected to cancel or postpone the surgical procedure. CONCLUSIONS: The incidence of previously unrecognized pregnancy in menstruating women presenting for ambulatory, nonobstetric surgery was 0.3%. The knowledge of a positive test resulted in cancellation or postponement of the operative procedure. Patient desire for cancellation was the main determining factor in each case.

Ambulatory Surgical Procedures↗
PubMed1994

Efficacy of the self-inflating bulb in detecting esophageal intubation. Does the presence of a nasogastric tube or cuff deflation make a difference?

BACKGROUND: The principle underlying the use of the self-inflating bulb in differentiating esophageal from tracheal intubation is that the trachea is held open by rigid cartilaginous rings, whereas the esophagus collapses when a negative pressure is applied to its lumen. This investigation was designed to test the efficacy of the bulb in detecting esophageal intubation in the presence of a nasogastric tube and after tracheal tube cuff deflation. METHODS: In anesthetized patients, the trachea and esophagus were intubated with identical tubes. The efficacy of the bulb was tested after a nasogastric tube was placed (group 1, n = 70) and after cuff deflation (group 2, n = 60) by a second anesthesiologist. RESULTS: In patients with nasogastric tubes (group 1), the anesthesiologists reported no reinflation of the compressed bulbs connected to tubes placed in the esophagus and immediate reinflation when connected to tracheally placed tubes in every case. In group 2, the determination of tube placement was correct in every case after cuff deflation. Mean (+/- SEM) negative pressures generated when compressed bulbs were connected to esophageally placed tubes were 57.8 +/- 0.48 mmHg (group 1) and 55.3 +/- 0.52 mmHg (group 2) and remained unchanged after the introduction of nasogastric tubes or after cuff deflation. CONCLUSIONS: These results confirm that a nasogastric tube or cuff deflation does not interfere with the reliability of the self-inflating bulb in detecting esophageal intubation and thus does not contribute to false positive results. Confirmation of tracheal tube placement by this simple method makes it ideal for use with other recognized methods both in and outside the operating rooms and enables physicians and emergency personnel to proceed with other resuscitative measures.

Adolescent↗
PubMed1993

Use of the self-inflating bulb for detecting esophageal intubation after "esophageal ventilation".

This present investigation tests the efficacy of the self-inflating bulb for detecting esophageal intubation after intentional "esophageal ventilation" to mimic gastric insufflation after bag-and-mask ventilation. In 72 anesthetized patients, the trachea and esophagus were intubated with identical tubes. The efficacy of the bulb was tested by a second anesthesiologist before and after the delivery of three breaths at a tidal volume of 300-350 mL each. The pressures generated by the bulb connected to esophageally placed tubes were measured in 10 patients. In all patients, the second anesthesiologist reported no reinflation of the bulbs when connected to esophageally placed tubes and instantaneous reinflation when connected to tracheally placed tubes, thus correctly identifying the location of each tube. The mean negative pressure generated when compressed bulbs were connected to esophageally placed tubes was 55.4 +/- 1.2 mm Hg before esophageal ventilation and 59.0 +/- 0.68 mm Hg after esophageal ventilation. We conclude that insufflation of the stomach as a result of esophageal ventilation, to the extent demonstrated in this study, does not interfere with the effectiveness of the bulb in differentiating esophageal from tracheal intubation.

Adult↗