PubMed Health⌕ Search

Biomedical subjects

M Garg

Publications and source records attributed to M Garg.

At least 55 records · Page 3Linked to original sources
PubMed1995

Measurement of lung volumes and pulmonary mechanics during weaning of newborn infants with intractable respiratory failure from extracorporeal membrane oxygenation.

Newborn infants with intractable respiratory failure who require extracorporeal membrane oxygenation (ECMO) experience diffuse pulmonary atelectasis shortly after initiation of ECMO. Atelectasis is likely due to the primary lung injury and the reduction of applied inspiratory ventilator pressure when the respirator settings are changed to the "rest settings." These pathophysiologic changes result in a decrease in lung compliance and lung volumes. We hypothesized that improving lung functions observed during ECMO and indicated by an increase in lung volumes will predict successful weaning from ECMO. Sixteen infants (mean +/- SEM: gestational age, 40.3 +/- 0.3 weeks; birth weight, 3.5 +/- 0.1 kg) with meconium aspiration syndrome (n = 13), sepsis (n = 2), and persistent pulmonary hypertension (n = 1) were studied. We measured passive respiratory system mechanics and lung volumes initially during full ECMO support (115 +/- 18 h on ECMO, Study I), and then within 24 h prior to weaning from ECMO (Study II). Respiratory system compliance (Crs), respiratory system resistance (Rrs), functional residual capacity (FRC), and tidal volume (VT) were measured. Prior to Study I lung volumes were too small to be detected. Crs increased between Study I and Study II (0.41 +/- 0.05 to 0.63 +/- 0.05 mL/cmH2O/kg, P < 0.05), and VT increased between Study I and Study II (5.6 +/- 0.6 to 10.4 +/- 0.8 mL/kg, P = 0.0005). FRC increased from 3.6 +/- 1.0 to 7.9 +/- 0.9 mL/kg (P = 0.0001). There was no change in Rrs (88 +/- 8 to 89 +/- 6 cm H2O/L/s, P = 0.9). The combination of Crs > 0.5 mL/cmH2O/kg and FRC > 5 mL/kg was a better predictor (P = 0.0002) of readiness to wean from ECMO than either Crs (> 0.5 mL/cmH2O/kg, P = 0.057) or FRC (> 5 mL/kg, P = 0.007) alone. The combination of FRC and Crs had a sensitivity of 73.3% and specificity of 100% for successful decannulation. We conclude that repeated measurements of FRC and Crs can assess lung recovery and may assist in establishing criteria for successful weaning from ECMO.

Extracorporeal Membrane Oxygenation↗
PubMed1995

Intratracheal pulmonary ventilation versus conventional mechanical ventilation in a rabbit model of surfactant deficiency.

Intratracheal pulmonary ventilation (ITPV) enhances the clearance of CO2 from dead space and lungs by a bias flow of gas administered in the distal trachea. ITPV flow is continuously administered through a separate catheter placed within an endotracheal tube (ETT). After exiting from catheter's tip in the distal trachea, the flow of gas is redirected outward away from the lungs. We hypothesized that, compared with conventional mechanical ventilation (CMV), ITPV may increase minute CO2 clearance (VCO2), reduce the partial pressure of CO2 dioxide in arterial gas (PaCO2), and reduce distal tracheal peak inspiratory pressure (dPIP). We induced surfactant deficiency in 15 adult rabbits by lung lavage with 10 mL/kg normal saline. Animals were ventilated through a double-lumen 4.0 ETT, inserted through a tracheotomy incision. dPIP, distal positive end expiratory pressure, and distal mean airway pressure were monitored, and the mean exhaled CO2 concentration was measured. For ventilator rates (respiratory rate) of 30, 45, and 70 breaths/min, the study included two phases: phase I compared CO2 clearance and PaCO2 between ITPV and CMV using similar ventilatory pressures; phase II evaluated the effectiveness of ITPV in reducing dPIP and tidal volume (Vt), compared with CMV, while maintaining eucapnea. When comparing ITPV and CMV, the following results (mean +/- SD) were achieved at respiratory rate of 30, 45, and 70 breaths/min, respectively. Phase I ITPV resulted in mean percent reduction of PaCO2 by 31.4 +/- 10%, 37.1 +/- 9.7% and 38.3 +/- 9%; mean percent increase in VCO2 by 61.3 +/- 29%, 56 +/- 23, and 98 +/- 40%, compared with CMV. Phase II ITPV resulted in mean percent reduction of dPIP by 35.5 +/- 14%, 38 +/- 10.8%, and 37.2 +/- 13.7%, and mean percent reduction in Vt by 34.7 +/- 12.9%, 36.4 +/- 15%, and 52.7 +/- 10.7%, compared with CMV. The changes in PaCO2, VCO2 (phase I), and dPIP and Vt (phase II) were all significantly more than 25% (p < 0.05). Oxygenation and pH were not significantly different between ITPV and CMV. We conclude that, in a surfactant deficiency rabbit model, ITPV is an efficient mode of assisted ventilation that increases CO2 clearance and reduces ventilator pressures required for adequate ventilation. We speculate that ITPV can minimize lung barotrauma associated with mechanical ventilation.

Animals↗
PubMed1995

Screening for HIV seropositive blood - a critical evaluation.

HIV screening of all donated blood is mandatory in India. The program instituted has many inherent lacunac like arbitrary identification of centres, absence of a guardian quality control program, criterion for test kit selection and absence of standard guidelines. This study was undertaken to evaluate the effects of frequent change of testing laboratory, change of testing staff, change of reagent kits and time of blood donation. All the donations at blood bank Safdarjang Hospital, during the year 1993, were taken for study. HBsAg and VDRL positivity were used as control/check value for similarity of donor population. Tests done during this period in three different laboratories show that the change of laboratory, change of reagent kit and the experience and training of the testing laboratory staff affect the test results, causing an increase in the number of false positive tests. This leads to destruction of donated blood which would have been otherwise fit for transfusion. It is suggested that a proper policy plan may be made and implemented in order to make the blood screening more effective.

AIDS Serodiagnosis↗
PubMed1994

Cellular basis of differential responsiveness of lymph nodes and spleen to 23-valent Pnu-Imune vaccine.

Subcutaneous administration with 23-valent pneumococcal polysaccharide vaccine (Pnu-Imune) elicited a good antipneumococcal capsular polysaccharide response from the spleen but not from peripheral lymph nodes (LN) (cervical, brachial, axillary, popliteal, inguinal) of BALB/c mice. To evaluate the cellular basis of the unresponsiveness of LN to this vaccine and to identify the cell types in spleen that are necessary for induction of polysaccharide Ab responses, a reliable in vitro culture system was developed to obtain plaque-forming cell responses to the Pnu-Imune vaccine. The in vitro antipneumococcal polysaccharide response of mouse spleen cells was found to be relatively T cell independent. Unlike spleen cells, LN cells did not respond to the Pnu-Imune vaccine in vitro. However, LN cells responded to Pnu-Imune vaccine when co-cultured with irradiated spleen cells or splenic dendritic cells but not with accessory cell-depleted spleen cells. LN cells were found to contain the necessary accessory cells that can support the polysaccharide response but in reduced numbers. The LN response to the vaccine was also reconstituted by IL-1 or Th2-associated cytokine IL-5. In contrast, IFN-gamma, a Th1 cell-derived lymphokine was able to suppress the in vitro splenic response to the vaccine suggesting that differential activation of Th1 and Th2 types of Th cells might be one mechanism by which T cells regulate Ab responses to pneumococcal polysaccharides.

Animals↗
PubMed1994

Feeding trans fatty acids to rats has no effect on the intestinal uptake of glucose, fatty acids or cholesterol.

Trans fatty acids are produced in the manufacture of margarine, and these hydrogenated fatty acids may have a deleterious effect on the reduction in fasting levels of serum cholesterol anticipated from the feeding of cis polyunsaturated fatty acids. We undertook this study in rats to test the effect of feeding trans fatty acids on the intestinal uptake of glucose, fatty acids and cholesterol. Adult female Wistar rats were fed for 2 weeks semisynthetic, isocaloric diets containing no oleic acid (18:1), cis 18:1 or trans 18:1. There was no difference between the three dietary groups in the animals' food consumption or body weight gain. Rats fed trans 18:1 had an approximately 20% decline in the total weight of the ileum as compared with controls fed no 18:1, and therefore there was also a decline in the percentage of the ileal tissue comprised of mucosa. When comparing rats fed trans 18:1 with those fed cis 18:1 or no 18:1, there was no difference in the uptake of varying concentrations of D-glucose when expressed as nmol.100 mg tissue-1.min-1 or nmol.100 mg mucosal-1.min-1 for jejunum or for ileum. Also, there was no difference in the value of the maximal transport rate (Vmax), Michaelis constant (Km), or the contribution of passive uptake of glucose assessed with L-glucose. There was no diet-associated change in the jejunal or ileal uptake of a medium-chain length fatty acid (lauric acid), a long-chain length saturated fatty acid (palmitic acid), a monounsaturated fatty acid (oleic acid), two polyunsaturated fatty acids (linoleic and linolenic acids), or cholesterol. Thus, we conclude that 2 weeks' feeding of trans fatty acid to rats has no influence on the jejunal or ileal uptake of glucose, fatty acids or cholesterol.

Absorption↗
PubMed1993

Patient mix in the primary ambulatory care clinics of an academic medical center.

BACKGROUND: The authors wished to learn whether the primary ambulatory care clinics of a university hospital had a sufficiently diverse patient mix for training in common medical problems. METHOD: Claims data for all the ambulatory care clinics at the University of Illinois Hospital from June 1989 through June 1990 were examined for principal diagnoses. The diagnoses were grouped into common ambulatory care diagnosis clusters. The frequencies of the clusters were compared with the national frequencies from the National Ambulatory Medical Care Survey of 1989. RESULTS: Only eight of 25 leading clusters nationally were seen with frequencies greater than 1% in the hospital's primary care clinics (i.e., family practice, general internal medicine, general pediatrics). This number increased to 22 when the clinics of other specialties were included. CONCLUSION: To create an appropriate patient mix for training medical students and residents in ambulatory care, the university hospital examined in this study could supplement the use of its primary care clinics with the use of clinics in other specialties. This may be a less expensive and administratively less complex alternative to using off-campus private practices for such training.

Academic Medical Centers↗
PubMed1993

Reversal of age-associated decline in immune response to Pnu-imune vaccine by supplementation with the steroid hormone dehydroepiandrosterone.

Recently, we reported that murine antibody responses to the 23-valent pneumococcal polysaccharide (Pnu-Imune) vaccine declined with age. Here we present data to support the concept that age-associated immune defects are not only due to intrinsic defects in immune cells but are also due to extrinsic factors emanating from the neuroendocrine system. We found that supplementation with dehydroepiandrosterone, a steroid hormone known to be reduced in the aged, corrects the immune deficiency of aged mice and significantly enhanced their splenic immune responses to the Pnu-Imune vaccine.

Age Factors↗
PubMed1992

Phospholipid and surfactant protein A concentrations in tracheal aspirates from infants requiring extracorporeal membrane oxygenation.

To test the hypothesis that infants with severe respiratory failure and the need for extracorporeal membrane oxygenation (ECMO) are surfactant deficient, we measured the amount of surfactant phospholipids, disaturated phosphatidylcholine, surfactant protein A, and protein in tracheal aspirates from 22 infants, who received ECMO therapy for respiratory failure with meconium aspiration syndrome (n = 18) or pneumonia (n = 4). Tracheal suction material was obtained in a standardized way every 4 hours during the period of ECMO treatment and pooled for 24-hour periods. During ECMO, mean total phospholipid, disaturated phosphatidylcholine, and surfactant protein A values in tracheal aspirates increased and protein values decreased significantly, predominantly during the 72-hour period before infants were weaned from ECMO. Of the 22 infants, 14 had an increase in tracheal aspirate phospholipid values of more than 200% and were found to need a shorter period of ECMO support (p less than 0.005) and post-ECMO ventilatory support (p less than 0.025) than did the eight infants with stationary or only moderate increases in tracheal aspirate phospholipid values, three of whom had pneumonia. We conclude that infants with respiratory failure who require ECMO treatment often have surfactant deficiency. We speculate that surfactant treatment might decrease the need for or the duration of ECMO support.

Extracorporeal Membrane Oxygenation↗
PubMed1992

Postoperative wound infections following myocutaneous flap surgery in spinal injury patients.

Severe pressure ulcers in patients with spinal cord injury are frequently treated by using musculocutaneous (m-c) flap surgery. There have been few studies of the use of perioperative antibiotics to prevent postoperative infection in this setting. We reviewed 74 m-c flap surgeries in 53 patients (41 male and 12 female) from October 1989 for one year. The sites involved were ischial (31), sacral (24), trochanteric (18), deltoid (2), olecranon (1) and posterior thigh (1). An antibiotic was usually administered perioperatively for 5 days. Patients were followed for a median of 30 (8-96) weeks. Postoperative infections occurred at a median of 12 (4-25) days in 6 of 74 (8%) surgeries. The organisms cultured from the 6 infected wounds were: Bacteroides sp. (4), Proteus mirabilis (2), E. coli (2), MRSA (2), and others (6--each isolated once). These results indicate that antibiotics did not prevent postoperative infection in approximately 8% of patients undergoing m-c surgery. The frequency of isolation of Bacteroides sp. from these infections suggests that anaerobic bacteria may persist in healing pressure ulcers and perioperative antibiotics might include coverage for anaerobic bacteria.

Adolescent↗
PubMed1992

Immune responses of systemic and mucosal lymphoid organs to Pnu-Imune vaccine as a function of age and the efficacy of monophosphoryl lipid A as an adjuvant.

A murine model system was established to study immune responses to the Pnu-Imune vaccine, which is made up of 23 different pneumococcal capsular polysaccharides. In this animal model, antibody-forming cell responses to 21 of 23 individual polysaccharides in the vaccine were detected. The Pnu-Imune vaccine elicited good antibody responses from the spleens and mesenteric lymph nodes (MLN) of young mice, whereas a variety of other peripheral lymph nodes were unresponsive. The immunoglobulin M plaque-forming cell (PFC) response in the spleen to the Pnu-Imune vaccine (given intraperitoneally or subcutaneously) decreased dramatically with increasing age. However, the spleen and MLN differed in their susceptibility to an age-associated decline in immune function. While the PFC responses in the spleen declined with age, the PFC response in the mucosa-associated MLN did not decline with age but instead remained constant over the entire age span of 4 to 28 months studied. These studies showed that the spleen, peripheral lymph nodes, and MLN did not demonstrate parallel age-associated defects in antibody responses to pneumococcal polysaccharides when the antigen was administered systematically. Also, the deficient splenic antibody response to Pnu-Imune vaccine in aged mice could be enhanced by injecting a combination of Pnu-Imune vaccine and the nontoxic adjuvant monophosphoryl lipid A. Moreover, an immunoglobulin G response was induced when the immunogen was a mixture of vaccine and adjuvant.

Adjuvants, Immunologic↗
PubMed1992

Pulmonary sequelae at six months following extracorporeal membrane oxygenation.

Mechanical assisted ventilation for neonatal respiratory failure is associated with residual lung disease. Because ECMO rests the lungs, it has been suggested that ECMO will prevent chronic lung disease in survivors. To determine whether or not ECMO survivors have evidence of pulmonary sequelae, we studied 19 infants who were treated with ECMO for neonatal respiratory failure. Ten infants still required supplemental oxygen or pulmonary medications or both to treat clinical lung disease during the first six months of life. Thoracic gas volume was normal. Pulmonary mechanics in ECMO survivors were compared with those of 13 preterm infants with BPD at similar age. We conclude that a significant proportion of ECMO survivors have residual abnormalities in pulmonary mechanics at 6 months of age. We speculate that neonatal lung injury due to meconium aspiration and other causes is a more important determinant of abnormal pulmonary sequelae than the method of treatment.

Bronchopulmonary Dysplasia↗
PubMed1991

The impact of extracorporeal membrane support in the treatment of congenital diaphragmatic hernia.

Neonates with congenital diaphragmatic hernia (CDH) treated by immediate surgical intervention and conventional ventilatory support have an overall poor survival. The potential of extracorporeal membrane oxygenation (ECMO) therapy to improve survival of infants with CDH remains controversial. Comparison was made in a single institution's pre-ECMO and post-ECMO survival statistics to establish efficacy of extracorporeal support for persistent pulmonary hypertension (PPH). This study was accomplished by stratifying patients by an oxygen index (OI). Sixty-eight patients were treated for CDH from 1977 to 1986 without ECMO. Fifty-eight patients underwent repair of CDH within the first 24 hours of life. Data could be retrieved for calculation of the OI in 46 patients. Nineteen patients developed an OI of 40 or greater; one survived (5%). Three of 27 patients with an OI less than 40 died (OIs = 34, 38, and 38). Thirty-one patients were treated from 1987 to 1989 and none were excluded from ECMO based on a minimum PO2. Fifteen had an OI less than 40 (range, 1 to 38), were treated conventionally, and 13 survived (87%). Sixteen patients had an OI greater than 40 and 13 qualified for ECMO. Nine of 13 survived (69%). Comparing pre-ECMO and post-ECMO survival for infants with an OI of 40 or greater (5% v 69%), there is a significant improvement in survival when ECMO is used (P less than .001). ECMO support offers a strong adjunct in management of neonates with CDH who develop PPH.

Extracorporeal Membrane Oxygenation↗
PubMed1991

Serial measurement of pulmonary mechanics assists in weaning from extracorporeal membrane oxygenation in neonates with respiratory failure.

Extracorporeal membrane oxygenation (ECMO) is a highly invasive therapy for intractable neonatal respiratory failure, and serious complications may occur with increasing duration of bypass. Weaning from bypass is empirical at present. Thus, there is a need to accurately predict when infants can be successfully decannulated. We hypothesized that pulmonary mechanics would reflect lung recovery and, therefore, predict successful weaning from ECMO. We measured pulmonary mechanics daily in 22 neonates, at gestational age of 37.8 +/- 0.6 weeks (SE) requiring ECMO for severe respiratory failure (oxygen index 66 +/- 6). Pulmonary resistance (Rpul), dynamic compliance (Cdyn), and tidal volume (VT) were measured. Rpul did not predict lung recovery. Cdyn within 24 hours of starting ECMO was 0.3 +/- 0.04 ml/cm H2O. Cdyn within 24 hours of weaning from ECMO was 1.2 +/- 0.09 ml/cm H2O (p less than 0.001). All 22 infants had Cdyn greater than 0.6 ml/cm H2O at the time of decannulation, but four infants (20 percent) with Cdyn less than 0.6 ml/cm H2O could not be weaned from ECMO within 20 hours (p less than 0.01). Thus, a minimum Cdyn of 0.6 ml/cm H2O is associated with successful weaning from ECMO. Cdyn of 0.8 ml/cm H2O provided better overall discrimination between those who could be successfully weaned from ECMO. We conclude that serial measurement of dynamic pulmonary compliance predicts successful weaning from ECMO.

Airway Resistance↗
PubMed1990

Endocrine regulation of calcium and phosphate in rat eye lens and its significance in cataract formation.

Parathyroid hormone (PTH), calcitonin (CT)and calciferol (Vit. D3) operate synchronously to maintain a balance between calcium and phosphate levels in serum. An aberration of specific steps in the homeostatic process results in hypo/hyper phosphatemia. These aberrations may eventually lead to several diseased states. PTH and Vit. D3 induced hypercalcemia can, however, be significantly inhibited by calcitonin (CT). These findings have been correlated with the levels of calcium and phosphate obtained from human senile cataractous lenses of cortical and nuclear types. The comparison of the results indicate that amongst these three hormones PTH is most vulnerable in leading towards conditions for possible cataract formation in rat lens.

Animals↗