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Biomedical subjects

O P Mathew

Publications and source records attributed to O P Mathew.

90 records · Page 5Linked to original sources
PubMed1980

Neonatal renal failure: usefulness of diagnostic indices.

Forty-two oliguric neonates were prospectively studied to evaluate the usefulness and reliability of various diagnostic indices in differentiating renal failure from functional (prerenal) oliguria. Twenty-two infants had functional oliguria, 16 had renal failure, and four infants had probable early renal failure. Statistically significant differences between functional oliguria and renal failure were found with regard to the urine sodium, urine to serum ratios of sodium, urea, and creatinine, renal failure index, and fractional excretion of sodium. However, sharp demarcation of the two groups was possible only when the renal failure index or fractional excretion of sodium was used. Fractional excretion of sodium values of 2.5 or greater seem to differentiate renal failure from functional oliguria in this study.

Acute Kidney Injury↗
PubMed1980

CSF lactate levels in high risk neonates with and without asphyxia.

Determination of CSF lactate levels were performed in 150 nonasphyxiated and 46 asphyxiated high risk neonates. Statistical analysis of log lactate levels of nonasphyxiated infants showed significant relationship to gestational and postnatal ages (P < .0001 and < .0002, respectively). CSF lactate elevation was seen in 16/29 infants studied within eight hours of asphyxia in contrast to 0/17 infants studied after eight hours (P < .001). Higher incidence of CSF lactate elevation was seen in term infants (7/8), infants with fetal distress (13/17), and very low Apgar scores (11/18). Seven of eight infants with markedly elevated lactate levels had both fetal distress and very low Apgar scores. CSF lactate determination in the immediate postasphyxial period appears to be an objective way of assessing the severity of cerebral hypoxia.

Apgar Score↗
PubMed1978

Effect of digoxin and diuretics on high altitude left ventricular dysfunction.

Systolic time intervals, stroke volume, cardiac output and (dZ/dt)/RZ index were serially estimated in 51 normal healthy volunteers at sea level, for ten days after air induction to 3658 m altitude and on return to sea level. The subjects were divided into three groups and were administered a diuretic, beta methyldigoxin and placebo in a double blind protocol. The group on placebo showed an increase in heart rate, reduction in stroke index and cardiac index during high altitude exposure with normalization on return to sea level. A deterioration in left ventricular function as manifested by prolongation of pre-ejection period, increase in PEP/LVET ratio, reduction in (dZ/dt)/RZ index and left ventricular ejection time was also noted at high altitude. The subjects on digoxin maintained normal stroke/cardiac index and did not show any significant changes in the parameters of myocardial function. The diuretic group showed more deterioration in the parameters than the placebo group. No significant side effects were noted. Left ventricular dysfunction and reduction of stroke index at high altitudes may be causually related; digoxin administration may prevent them from occurring.

Adult↗
PubMed1977

Changes in transthoracic electrical impedance at high altitude.

Mean transthoracic electrical impedance (impedance) which is inversely related to intrathoracic extravascular fluid volume was measured in 121 normal healthy volunteers at sea-level and at 3658 metres altitude. Fifty (group A) reached the high altitude location after an hour's journey in a pressurised aircraft. Twenty-five (group D) underwent slow road ascent including acclimatisation en route. Thirty permanent residents (group B) and 16 temporary residents at high altitude (group C) were also studied. Serial studies in the 30 subjects of group A who developed symptoms of high altidue sickness showed a significant decrease of impedance up to the fourth day of exposure to high altitude which later returned to normal. The 4 volunteers who developed severe symptoms showed the largest drop in impedance. A case of acute pulmonary oedema developing at 4300 metres showed an impedance value of 24-1 ohms on admission. After effective treatment the impedance increased by 11-9 to 36-0 ohms. Twenty asymptomatic subjects of group A and 25 of group D showed a small average increase in impedance values at high altitude. These obstructions suggest that measurement of transthoracic electrical impedance may be a valuable means of detecting incipient high altitude pulmonary oedema.

Acclimatization↗
PubMed1977

Effect of high-altitude exposure for 10 days on stroke volume and cardiac output.

Resting stroke volume and cardiac output of 50 normal healthy sea-level residents (group A) were estimated by the noninvasive technique of electrical impedance plethysmography. They were then airlifted to an altitude of 3,658 m and serial estimations carried out at 0-4 h and 5-8 h and on the 2nd, 3rd, 4th, 5th, and 10th days. The subjects were brought back to sea level and studied for up to 5 days. Thirty permanent residents of high altitude (group B) and sixteen lowlanders temporarily resident at high altitude (group C) were also subjected to similar studies. It was found that resting stroke volume and cardiac output of group A started falling immediately on arrival at high altitude, reached the minimum on the 3rd day and tended to improved on the 4th and 5th day, but showed a secondary fall on the 10th day. The reduction in stroke volume in this group was not fully compensated by tachycardia. On return to sea level the cardiac output normalized immediately, the stroke volume on the 2nd day. At sea level goup A had values similar to group B and at high altitude to group C.

Adult↗
PubMed1976

Urinary catecholamine excretion on acute induction to high altitide (3,658 m).

Fifty healthy male volunteers, 21-34 yr of age, normally resident at altitudes less than 1,000 m, were airlifted to 3,658 m. Urinary excretion of catecholamines was measured at sea level (198 m) and on the 1st, 2nd, 4th, and 10th day of a stay at high altitude. The symptoms observed on exposure to high altitude were assigned arbitrary scores. The volunteers could, on this basis, be divided into "symptomatic" and "asymptomatic" groups. The two groups showed a markedly different pattern of urinary catecholamines excretion on exposure to high altitude and on return to sea level. Significant increase in the catecholamine excretion was observed in the symptomatic group only. A possible role for enhanced sympathoadrenal activity in the etiopathogenesis of high-altitude illnesses is postulated.

Adrenal Glands↗
PubMedDate not supplied

Breathing pattern of neonates during nonnutritive sucking.

Alteration of the breathing pattern seen during oral feeding has been attributed to the behavioral activity of sucking, repeated swallowing, and laryngeal chemoreceptor stimulation. Because it preserves the behavioral activity of sucking but eliminates the laryngeal chemoreceptor stimulation and repeated swallowing that occurs during nutritive sucking, the effects of nonnutritive sucking was evaluated in 19 term infants. The suck-pause pattern seen during nonnutritive sucking is similar to that of nutritive sucking. None of the variables measured (inspiratory duration, expiratory duration, breathing frequency, and tidal volume) were significantly altered during the overall period of nonnutritive sucking when compared with previously obtained control values. These results suggest that the alteration of breathing pattern observed during oral feeding cannot be accounted for by the behavioral activity of sucking per se. However, when the sucking phases of the nonnutritive period were compared with the intervening pauses, a reduction in the expiratory duration (P less than 0.05) and a reduction in tidal volume (P less than 0.05) were observed. Thus, the breathing pattern of human neonates is indeed altered during the sucking phase of the nonnutritive period; pressure changes associated with sucking may account for this alteration.

Humans↗
PubMedDate not supplied

Neonatal apnea.

Explore the source record for details and available documents.

Apnea↗
PubMedDate not supplied

Does supine positioning increase apnea, bradycardia, and desaturation in preterm infants?

OBJECTIVE: The purpose of this study was to determine the effects of prone and supine positioning on the cardiorespiratory stability of preterm infants with apnea and bradycardia. METHODS: A total of 22 preterm infants with symptomatic apnea and bradycardia (gestational age of 26.9 +/- 1.8 weeks and birth weight of 865 +/- 235 gm) were monitored for 24 hours (in four sequential 6-hour blocks) for apnea, bradycardia, and oxygen desaturation in alternating positions (prone or supine) following randomization. Postconceptional age at the time of study was 31.9 +/- 3.0 weeks. Respiratory rate, heart rate, and transcutaneous oxygen saturation were continuously monitored. All episodes of apnea (> or = 10 seconds), bradycardia (< 100 beats per minute), and oxygen desaturation (< 90%) were recorded on an event monitor. Episodes of apnea, bradycardia, and oxygen desaturation were defined as clinically significant if the following criteria were met: apnea, > or = 15 seconds; bradycardia, < 90 beats per minute; and oxygen desaturation, < 80%. All other recorded episodes were considered mild. The episodes were analyzed for statistical significance using the paired t-test. RESULTS: No significant differences (p > 0.05) in the incidence of clinically significant apnea, bradycardia, or desaturation between supine and prone positions were seen in these preterm infants. CONCLUSION: Our results suggest that the cardiorespiratory stability of preterm infants is not significantly compromised by supine positioning.

Apnea↗
PubMedDate not supplied

Respiratory activity of the cricothyroid muscle.

Single motor units of the cricothyroid muscle (CT), the contralateral CT electromyogram, and the posterior cricoarytenoid muscle (PCA) electromyogram were recorded in anesthetized, spontaneously breathing dogs. In quiet breathing the CT was active predominantly in inspiration, and distinct phasic expiratory activity was observed at lighter levels of anesthesia. Both the CT and PCA increased their inspiratory and expiratory activity with hypercapnia, whereas only their inspiratory activity increased in response to negative pressure and/or absence of volume feedback. Cold blockade of either the recurrent laryngeal nerves or the external branch of the superior laryngeal nerves did not modify CT or PCA activity. In general, activity of CT motor units reflected the behavior of the whole muscle, but different units were recruited at different levels of CT activity. Even though the majority exhibited similar thresholds for inspiration and expiration, some units showed a lower threshold for either one, suggesting some degree of specialization. However, for a few units with high threshold for inspiration the expiratory threshold could not be determined, since a comparable level of CT activity was not achieved in expiration.

Animals↗