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Biomedical subjects

B A Chaudhary

Publications and source records attributed to B A Chaudhary.

At least 19 recordsLinked to original sources
PubMed1992

Case report: multiple negative polysomnograms in patients with obstructive sleep apnea.

A single overnight polysomnogram usually is adequate to exclude a diagnosis of obstructive sleep apnea. We report three patients who had multiple negative polysomnograms before a diagnosis of sleep apnea was made. Factors that may cause a false-negative polysomnogram include reduced total or rapid eye movement sleep time, sleeping in the lateral posture, manifestation of the disease predominantly by hypopneas, and recent medical therapy to treat sleep apneas. In patients with a strong clinical suspicion of sleep apnea and a negative polysomnogram, sleep and clinical parameters should be reevaluated and a repeat polysomnogram may be indicated.

Adult↗
PubMed1992

Negative polysomnogram in patients with obstructive sleep apnea syndrome.

We evaluated the possibility that in some patients with obstructive sleep apnea, the initial polysomnogram may be negative. We reviewed polysomnograms performed at the Medical College of Georgia from 1984 to 1990 and found nine patients whose initial polysomnogram was negative but whose repeat polysomnogram confirmed obstructive sleep apnea. All nine patients (five women and four men; average age, 44.2 years) had an apnea index of less than 5 (fewer than five apneic episodes per hour) and had a total of fewer than 20 apneic episodes during the initial overnight polysomnogram. The change in average weight was not significant. Three patients had received short-term oxygen therapy, and two of these three received nasal continuous positive airway pressure prior to the initial study. The time that patients spent supine increased from 101 min in the initial study to 180 min in the second, but this was not significant (p = 0.12). Comparison of the initial and diagnostic polysomnograms showed significantly reduced total sleep time (from 3.75 +/- 1.84 h to 5.32 +/- 1.11 h; p = 0.04) and reduced rapid eye movement (REM) sleep time (from 0.27 +/- 0.27 h to 0.75 +/- 0.58 h; p = 0.037) in the initial study. We conclude that in a small subset of patients with obstructive sleep apnea, the initial polysomnogram may be falsely negative, which could be due to previous therapy, a reduction in total sleep time and REM sleep, or other unidentified factors.

Adult↗
PubMed1992

Intracranial hemodynamics in sleep apnea.

Intracranial pressure changes and poor cerebral perfusion have been reported in sleep apnea syndrome (SAS), but such studies have been limited due to lack of a reliable noninvasive study method. We determined the systolic (VS), diastolic (VD), and mean (VM) cerebral blood flow velocities of the middle cerebral artery in 23 individuals (12 severe SAS patients and 11 control subjects) using transcranial Doppler sonography before sleep, during sleep (NREM and REM) and upon awakening. All three velocities (VS = 87.4 cm/s compared to 104.7 cm/s, VD = 41.6 cm/s compared to 47.7 cm/s, and VM = 57.0 cm/s compared to 67.0 cm/s) were decreased in patients with SAS and VS and VM were significantly lower than in control subjects (p = 0.005 and p = 0.033, respectively). The end-tidal CO2 (PETCO2) in the SAS patients (47.3 mm Hg) compared to the control subjects (41.8 mm Hg) was significantly higher (p = 0.003). When the VM was adjusted to normalized CO2 using the Markwalder's equation, the reduction in velocity in patients with SAS (47.5 cm/s) compared to control subjects (63.0 cm/s) became more significant (p = 0.005). This study shows that cerebral blood flow velocities are lower in patients with SAS compared to control subjects and that transcranial Doppler sonography may be useful in such evaluations.

Adult↗
PubMed1991

The effect of sleep on intracranial hemodynamics: a transcranial Doppler study.

The effect of sleep on intracranial blood flow velocities has not been reported in children or adults, even though blood flow velocities are evaluated for clinical purposes during both sleep and wakefulness. We report the effect of sleep on intracranial blood flow velocities of 11 healthy individuals (five children and six adults) who were monitored by polysomnography and transcranial Doppler sonography (TCD). Thirty-three TCDs were obtained on middle cerebral arteries. Before sleep, during non-rapid-eye-movement sleep, and after sleep, measurements of systolic, end diastolic, and mean flow velocities were obtained by TCD. Pulse oximetry and end tidal carbon dioxide were monitored during each 8-hour polysomnogram. The before-sleep blood flow velocity values were compared to sleep and after-sleep values in children and adults separately using ANOVA. A significant decrease in the blood flow velocities was noted during sleep compared to before-sleep values in both children (P less than .05) and adults (P less than .01). The blood flow velocities after sleep were also decreased compared to before-sleep values. This study shows that sleep reduces blood flow velocities in both children and adults. A decrease in blood flow velocities during normal sleep should be taken into account when interpreting TCDs in patients.

Adolescent↗
PubMed1991

Obstructive sleep apnea syndrome.

Over the past 2 decades, we have gained great insight into the sleep apnea syndromes. Though progress in this field continues, many problems, including an incomplete understanding of the disease and its natural history, remain. Future work should clarify these areas as well as provide a better understanding of our available therapeutic options.

Humans↗
PubMed1990

Reduction of peak inspiratory pressure using high frequency jet ventilation and pressure control ventilation following pneumonectomy.

High peak inspiratory pressure (PIP) during mechanical ventilation is associated with increased risk of barotrauma. High frequency jet ventilation (HFJV) and pressure control ventilation (PCV) have been advocated for the reduction of PIP. The Food and Drug Administration has approved HFJV, respiratory frequency as high as 150 breaths per minute (bpm); however, bpm greater than 150 are still considered for experimental use. At less than 40 bpm, the point where HFJV is no longer considered to be high frequency, PCV is substituted which then becomes the mode of choice because of the ability to control ventilating pressures by setting the PIP. We present a case in which we used these two forms of ventilation for reducing the risk of stump blowout and barotrauma following pneumonectomy.

Barotrauma↗
PubMed1989

Effect of glucocorticoids on the response of airway smooth muscle to catecholamine and resorcinol beta-agonists.

The influence of hydrocortisone (11 beta, 17 alpha, 21-trihydroxy-pregn-4-ene-3,20-dione) or of methylprednisolone (6 alpha-methyl-11 beta, 17 alpha-21-trihydroxy-1,4-pregnadiene-3,20-dione) on the response of airway smooth muscle to a variety of beta-adrenergic bronchodilators was evaluated using incubated guinea pig tracheal rings, preconstricted with histamine. The adrenergic agonists chosen for this study included the nonselective beta 1- and beta 2-catecholamine, isoproterenol, the selective beta 2-catecholamine, rimiterol, and the selective beta 2-resorcinols, fenoterol and terbutaline. When the incubated rings were pretreated with 10-50 micrograms/mL of the steroids, there was a significant enhancement in smooth muscle sensitivity and reactivity to rimiterol and isoproterenol. Tracheal response to fenoterol or terbutaline, on the other hand, was not altered by the glucocorticoids. When used alone, neither steroid exerted an inotropic influence on the tracheal smooth muscle. The results of our study indicate that glucocorticoid enhancement of adrenergic bronchodilators is selective for catecholamines, and not for resorcinols.

Adrenergic beta-Antagonists↗
PubMed1989

Nocturnal urinary protein excretion rates in patients with sleep apnea.

We observed nocturnal urinary protein excretion to be 16.2 +/- 5.5 micrograms/min (mean +/- SE) in 9 healthy control subjects (group I), 29.3 +/- 9.5 micrograms/min in 12 obese patients suspected to have obstructive sleep apnea syndrome (OSAS) but with negative polysomnographic studies (group II), and 94.0 +/- 31.8 micrograms/min in 14 patients with documented OSAS (group III) (II vs. I, NS; III vs. I, p less than 0.05; III vs. II, p less than 0.05). The frequency of abnormal proteinuria, defined as protein excretion greater than the highest rate observed in group I (46 micrograms/min), was 14% in group II and 64% in group III (p less than 0.05). There were no significant differences in age, body weight, body surface area, blood pressure, or indices of sleep apnea between OSAS patients with and without proteinuria. Although the mechanism is unclear, this study shows that nocturnal protein excretion rates are commonly elevated in patients with OSAS.

Adult↗
PubMed1989

Effects of oral base therapy on serum ionized calcium, phosphorus and parathyroid hormone in chronic hemodialysis patients.

The purpose of this study was to evaluate the effects of oral base therapy on selected chemical parameters in chronic hemodialysis patients. Oral base supplements were administered to 20 acidotic chronic hemodialysis patients for one month. Serum bicarbonate levels rose from 18.6 +/- 2.9 to 22.5 +/- 4.0 mEq/L (p less than 0.0005) and pH rose from 7.35 +/- 0.03 to 7.39 +/- 0.04 (p less than 0.0005). Serum ionized calcium levels fell from 5.03 +/- 0.37 to 4.83 +/- 0.34 mg/dL (1.25 +/- 0.09 to 1.21 +/- 0.08 mmol/L) (p less than 0.01), while intact parathyroid hormone (PTH) levels rose from 547 +/- 697 to 619 +/- 776 pg/mL (p less than 0.05). Base therapy did not result in significant changes in serum levels of total calcium, phosphorus, alkaline phosphatase, urea nitrogen, creatinine, total protein, albumin or potassium. If empiric therapy with exogenous base is given to dialysis patients, ionized calcium levels should be closely monitored since changes in calcium supplement or vitamin D therapy may be required to maintain ionized calcium and parathyroid hormone values at the pre-treatment levels.

Acidosis↗
PubMed1989

Methotrexate pneumonitis: a case report and summary of the literature.

Methotrexate is used to treat a growing number of malignancies, severe rheumatoid arthritis, and refractory psoriatic arthritis. Pneumonitis induced by the drug occurs in a small percentage of patients and is usually associated with fever, cough, dyspnea, and restrictive pulmonary disease. Severe reactions may progress to respiratory failure. Early recognition of the toxicity is important, and discontinuation of the drug and therapy with corticosteroids usually lead to dramatic improvement.

Aged↗
PubMed1988

Sleep apnea and hypothyroidism.

Thyroid deficiency states are now a well recognized cause of the sleep apnea syndrome. The spectrum of disease ranges from mild, asymptomatic hypothyroidism to severe myxedema, and the disorder is associated with both obstructive and central types of sleep apnea. A variety of factors may be involved, including upper airway obstruction with or without obesity, and alterations in ventilatory drive. The definitive therapy is thyroid hormone replacement, which has been shown to diminish or completely eliminate apneic episodes and arterial oxygen desaturation, as well as to effect many improvements in sleep patterns and overall sleep efficiency. The incidence of thyroid deficiency states in patients with sleep apnea syndrome is not known, but it seems reasonable to evaluate thyroid function in all patients. Thyroid replacement therapy seems logical for the treatment of sleep apnea in patients with previously unrecognized subclinical hypothyroidism. Much remains to be learned about the diagnosis and treatment of sleep apnea syndromes associated with thyroid hormone deficiency, and further studies are needed.

Humans↗
PubMed1988

Correlates of amylase and lipase levels in chronic dialysis patients.

Serum lipase and amylase isoenzymes were measured in 44 chronic hemodialysis patients, 16 CAPD patients and 22 normal volunteers. The enzyme levels of the two patient groups were similar and were significantly higher than those of the volunteer group. The ratio of pancreatic to salivary amylase was similar in all three groups. Anuric patients in both dialysis groups had higher enzyme levels than those with residual urine output. Linear regression analysis was done to attempt to identify factors which were good predictors of enzyme levels. Although no such factors were found in the hemodialysis group, in the CAPD group there were significant correlations between the degree of azotemia and the magnitude of enzyme elevations. Further studies are needed to determine the relative importance of oversecretion and underexcretion in the genesis of the amylase and lipase elevations found in dialysis patients.

Amylases↗
PubMed1979

Effect of lidocaine anesthesia on pattern of ventilation and pulmonary function tests.

The pattern of ventilation (consisting of tidal volume, frequency of breathing, minute ventilation, peak inspiratory flow rate, inspiratory time, mean inspiratory flow rate, and inspiatory time ratio) and pulmonary function tests (consisting of spirometry, lung volumes, and airway resistance) were measured in ten conscious, healthy subjects before and after anesthesia of the airways achieved by inhalation of lidocaine, to determine the role of the vagus nerves in the control of eupneic breathing. No significant change was found in the pattern of ventilation or in pulmonary function tests after airway anesthesia. These results are consistent with the observation that the vagus nerves do not play an important role in the control of eupneic breathing in humans.

Adult↗
PubMed1979

Cardiac rhythm disturbances during fiberoptic bronchoscopy: a prospective study.

Twenty-six patients undergoing transnasal fiberoptic bronchoscopy (FOB) were electrocardiographically monitored for 12 hours before, during, and 12 hours after bronchoscopy. We measured arterial lidocaine concentrations during the procedure as well as arterial blood gases before and after the procedure. The incidence of total arrhythmias, including sinus tachycardia, during the control period was 69 percent; minor arrhythmias, 69 percent; and major arrhythmias, 8 percent. During FOB, the incidence of total and minor arrhythmias increased to 77 and 73 percent, respectively; however, the incidence of major arrhythmias decreased to 4 percent. Arterial lidocaine concentrations ranged widely, from 0.1 to 8.7 microgram per milliliter with a mean peak level of 5.0 +/- 0.6 microgram per milliliter, which was reached between 5 and 30 minutes after the insertion of the bronchoscope. We conclude that the incidence of cardiac arrhythmias, excluding sinus tachycardia, during FOB is low and that lidocaine anesthesia probably exerts a protective effect against the development of major arrhythmias during the procedure.

Adult↗
PubMed1978

Effects of airway anaesthesia on the ability to detect added inspiratory resistive loads.

1. The effects of airway anaesthesia on the ability to detect added inspiratory resistive loads were studied in normal subjects. A 4% solution of lignocaine hydrochloride was used for anaesthesia of the airways. 2. After anaesthesia of the mouth and upper airways to the level of the vocal cords there was a significant deterioration in the detection ability expressed in terms of the absolute added resistance (deltaR), with a concomitant increase in pulmonary resistance (Rint.). However, there was no significant change in the detection ability expressed in terms of the ratio of deltaR to the sum of Rint. and the minimal resistance of the apparatus (deltaR/Ro). 3. After combined anaesthesia of the upper and lower airways there was no significant change in pulmonary resistance or in the detection ability expressed either as deltaR or as deltaR/Ro. 4. We conclude that, in normal subjects, the main site of detection of added inspiratory resistive loads does not lie in the upper or lower airways. Our results and those of previous studies suggest that the diaphragm is the most likely site of detection of added resistive loads.

Adult↗
PubMed1978

Ear oximetry in clinical practice.

The arterial blood O2 saturation measurement obtained by the Hewlett-Packard ear oximeter was compared to that derived from the arterial PO2 in 41 patients with various pulmonary diseases and in 11 jaundiced patients with serum bilirubin concentrations between 2.7 and 35 mg per 100 ml. There was a good correlation between results obtained with the 2 methods in the jaundiced group (r = + 0.85, n = 19) and in the patients with pulmonary disease (r = + 0.90, n = 57); however, in the jaundiced patients, the ear oximeter arterial O2 saturation was significantly lower (-6.06 per cent, n = 19, P less than 0.01) than the arterial O2 saturation derived from the arterial PO2. There was a significant correlation between the serum bilirubin concentration and the magnitude of difference between the oximeter arterial O2 saturation and the arterial PO2-derived arterial O2 saturation (r = + 0.848, n = 16, P less than 0.001). In the nonjaundiced patients, the difference between the 2 measurements was small when the arterial P(02) was greater than 61 mm Hg; the variation increased with lower arterial PO2 concentrations, but the difference was not significant.

Ear↗