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Biomedical subjects

W H Tooley

Publications and source records attributed to W H Tooley.

At least 37 records · Page 2Linked to original sources
PubMed1981

Effect of oxygen administration during sleep on skin surface oxygen and carbon dioxide tensions in patients with chronic lung disease.

Hypoxemia, hypercarbia, and cor pulmonale ultimately occur in most patients with chronic lung disease. Although oxygen therapy may reduce or delay the development of pulmonary hypertension and myocardial failure in these patients, its use is thought to lead to CO2 narcosis and apnea. The effect of O2 administration during sleep has been examined in 12 patients (seven with cystic fibrosis, three with bronchopulmonary dysplasia, one with bronchiolitis obliterans, and one with severe hypersensitivity pneumonitis) using skin surface O2 (Roche) and CO2 (Radiometer) electrodes. Both electrodes were calibrated over wet gas and applied at 44 C. Ten patients had chronic hypercarbia (PaCO2 62 +/- 19 torr; range 46 to 103 torr) when awake. Humidified oxygen was administered by nasal cannula, Venturi mask, or head hood. Oxygen flow was increased every 20 minutes from 80 minutes or until the patient awoke. In eight of ten patients with hypercarbia and in the two normocarbic patients, skin surface carbon dioxide tension (PsCO2) increased by 10% or less as the skin surface oxygen tension (PsO2) was increased. In the remaining two patients with hypercarbia (both had cystic fibrosis) PsCO2 increased 18% and 24% as PsO2 was increased. These last two patients with depressed responsiveness to CO2 could not be separated from the other patients by clinical or laboratory criteria. It is concluded that the skin surface blood gas tensions are a simple and reproducible method for adjusting oxygen therapy in patients with chronic lung disease, and although the response to oxygen varies from patient to patient, most patients with chronic hypercarbia retain their central responsiveness to CO2 during sleep and for them O2 therapy is probably safe.

Adolescent↗
PubMed1980

Differential development of brainstem potentials in healty and high-risk infants.

Maturation along the brainstem acoustic pathway, as well as the integrity of these structures, has been shown to be reflected in brainstem evoked potential recordings. Trajectories formed from repeated sequential measurements of several brainstem response variables reveal distinct developmental curves for healthy and high-risk infants. Longitudinal analysis offers a means of determining temporary or permanent maturational effects on the central nervous system in early life.

Age Factors↗
PubMed1980

Contrasts in brainstem function between normal and high-risk infants in early postnatal life.

Brainstem auditory evoked potentials (BAEPs) were recorded from healthy and high-risk infants at selected ages throughout their first year of life. Amplitude and latency measurements of peaks I, III and V were treated in a series of multivariate analyses of variance. Significant main effects for age (newborn, 3 wk, 6 wk, 3 mth, 6 mth and 1 yr), group (healthy, risk) and peaks (amplitude and latency of BAEP waves I, III and V) were observed. In addition, the interaction between these factors proved statistically significant. As expected, the pattern of response amplitude and latency for the various peaks differed as a function of age. Moreover, healthy and risk infants revealed different maturational trends. These results indicate that infants born 'at risk' but free of severe auditory deficits and major neurological difficulties can be distinguished from healthy (age-matched) controls in terms of the BAEP throughout the first postnatal year.

Brain Stem↗
PubMed1980

Continuous measurements of skin surface oxygen and carbon dioxide tensions in obstructive sleep apnea.

We have found that skin surface electrodes for continuously measuring oxygen (PSO2) and carbon dioxide (PSCO2) tensions provide reliable means of determining whether infants with apnea due to airway obstruction during sleep require treatment. Nine patients referred for evaluation of aqnea during sleep were studied. In 6 patients with PSO2 less than 50 torr during sleep, the hypoxic episodes were clearly associated with partial or total airway occlusion as judged by increasing respiratory effort without concomitant airflow. PSCO2 was found to increase during the episodes of obstruction in all 6 patients. These patients were treated with 1. tracheotomy, 2. tonsillectomy and adenoidectomy in 2 patients, 3. bilateral mandibular condylotomies, 4. pharyngeal flap release, and 5. discontinuing topical nasal decongestants. After treatment, all had decreased hypoxia, hypercarbia, or airway obstruction. Two of the remaining 3 patients had no alterations of PSO2 or PSCO2 associated with airway obstruction during sleep. The third exhibited hypoxia and hypercarbia secondary to central apnea. We conclude, therefore, that continuous monitoring of skin surface oxygen and carbon dioxide tensions is useful in evaluating children with obstructive sleep apnea.

Airway Obstruction↗
PubMed1980

Posthemorrhagic hydrocephalus in the preterm infant.

Between 1969 and 1978 we treated 22 low birth weight infants for delayed onset posthemorrhagic hydrocephalus. All developed clinical signs of hydrocephalus after 2 weeks of age. The diagnosis was determined in 12 infants before August 1974, and they were treated by surgical placement of a shunt. In the ten infants born after September 1974, an attempt was first made to control the hydrocephalus with repeated lumbar puncture and diuretics prior to placing a shunt. In seven of the ten the hydrocephalus was successfully arrested by medical therapy alone. Follow-up assessments at 1 to 8 years of age were done on 18 infants. Two of the 12 treated by permanent shunts and three of six treated medically had an IQ score of 85 or greater. These results indicate a poor long-term outlook for the low birth weight infant who develops clinically overt hydrocephalus after intracranial bleeding.

Acetazolamide↗
PubMed1979

Antenatal prediction of graduated risk of hyaline membrane disease by amniotic fluid foam test for surfactant.

We measured amniotic fluid surfactant by the semiquantitative foam stability test within 24 hours before delivery of 410 infants, 64 of whom developed HMD diagnosed by standard criteria. When surfactant titers were ranked in eight categories, they predicted graded risks of HMD. On this basis we defined five "risk groups" with significantly different incidences of HMD (I = 0.5%; II = 10%; III = 25%; IV = 41%; V = 79%). Infants in Groups I and II were heavier and more mature than those in Groups III to V. However, among infants of equivalent GA or birth weight, the incidence of HMD still correlated significantly with the foam test results. Within each risk group the incidence of HMD was equal among infants delivered by vagina and by cesarean section, slightly greater among males than females, and inversely proportional to GA. In Group V the incidence of HMD was 100% among infants at less than 33 weeks' GA. We used this relationship to devise a system that improved prediction of HMD by combining the foam test results with GA.

Amniocentesis↗
PubMed1979

Tracheal fluid in fetal lambs: spontaneous decrease prior to birth.

We studied tracheal fluid (TF) production in 14 fetal lambs: 6 controls, 6 receiving atropine on 1 or more of the last 7 days before birth, and 2 with bilateral section of the cervical vagosympathetic trunk. A cannula diverted all TF into an intrauterine bag; we collected TF intermittently and measured its volume. All ewes delivered spontaneously at 128-150 days' gestation. TF production decreased before birth in all fetuses except one control. TF production decreased before birth in all fetuses except one control. TF production did not correlate with fetal arterial blood gas tensions, hematocrit, or plasma proteins. In controls only, TF production correlated with fetal arterial pH (P less than 0.02); however, the pH range was small and the correlation has questionable physiological significance. For all fetuses, TF production during the 7 days before birth correlated inversely with the plasma cortisol concentration of 48 h previously (n = 36; r = -0.603; P less than 0.001). We conclude a) TF production in fetal lambs decreases before spontaneous term or preterm labor; b) this decrease is not affected by atropine or by section of the cervical vagosympathetic trunk; and c) the decrease in TF production may be related to increased secretion of cortisol.

Animals↗
PubMed1979

Skin surface carbon dioxide tension in sick infants.

Skin surface PCO2 (PSCO2) was measured at 44 C in 17 sick infants using a Radiometer surface PCO2 electrode. Values obtained for PSCO2 were compared with simultaneous values for arterial PCO2 (PaCO2). PSCO2 was found to be linerarly related to PaCO2 by a regression line with a slope 1.37. PaCO2 could be predicted from PSCO2 to within 6 torr in all instances. The relationship was not affected by the patient's gestational age, postnatal age, weight, or blood pressure. This electrode is a valuable clinical tool in the management of sick infants.

Arteries↗
PubMed1979

Stimulation of breathing movements in fetal sheep by inhibitors of prostaglandin synthesis.

We studied the effects of inhibitors of prostaglandin synthesis on fetal breathing movements on 17 occasions in 11 lambs (gestational age 125-141 days). We gave 12 h infusions of sodium mechlofenamate (8.6-22.2 mg.kg-1) in 13 studies and indomethacin (21.8-38.8 mg.kg-1) in four studies. Results were similar with both agents and did not correlate with drug dosage. There were no changes in fetal arterial blood pressure, pH or blood gas tensions. We assessed fetal breathing movements by measurements of tracheal pressure for a control period of 224 h prior to and 208 h during the infusion of inhibitors of prostaglandin synthesis; their administration caused a marked stimulation of fetal breathing movements judged from the following four variables: (1) incidence of fetal breathing movements increased from 38.4 to 69.2% of the time (P < 0.001); (2) average amplitude of change in tracheal pressure during fetal breathing movements increased from 4.1 to 6.0 torr (P < 0.01); (3) maximal amplitude of change in tracheal pressure during fetal breathing movements increased from 8.8 to 13.4 torr (P < 0.01); and (4) the duration of the longest continuous episode of fetal breathing movements increased from 37 to 229 min (P < 0.05). Two fetuses had electrocorticogram (ECoG) recordings. In control periods, fetal breathing movements occurred only during low voltage, high frequency ECoG activity; however, during infusions of inhibitors of prostaglandin synthesis, fetal breathing movements occurred also during high voltage, low frequency ECoG activity. We conclude that inhibitors of prostaglandin synthesis stimulate fetal breathing movement in fetal sheep. These results suggest that a component of the prostaglandin system is a factor which inhibits breathing movements during fetal life.

Animals↗
PubMed1978

Clinical limitations and advantages of transcutaneous oxygen electrodes.

We investigated the clinical use and limitations of the transcutaneous oxygen electrode described by Huch, Lübbers and Huch in 30 sick infants. One hundred and fifty-nine measurements of arterial oxygen tension (PaO2) and transcutaneous oxygen tension (tcPO2) were made. During the comparisons, arterial blood pressures, heart rate thoracic impedance were continuously recorded, skin axillary and environmental temperatures, hematocrit and skin thickness were measureed and the degree of peripheral perfusion noted. Despite a wide range of these variables, values of tcPO2 and PaO2 were similar (slope 0.963). Two groups of infants were identified in whom tcPO2 was lower than PaO2. These were infants receiving an intravascular infusion of tolazoline and infants with mean arterial blood pressures more than 2.5 s.d. below the predicted average value. Both of these situations represent extreme alterations in peripheral blood flow and give important information regarding the limitations of the method. Less extreme alterations in flow caused by mild hypotension, hypothermia, anemia, radiant warmers, and bilirubin lights did not adversely affect the transcutaneous PO2--arterial PO2 correlation. Advantages of transcutaneous oxygen monitoring over more conventional monitoring methods were assessed. We conclude that the transcutaneous oxygen electrode is safe, is easy to use, has few limitations and provides data which can help improve the management of most sick infants.

Blood Gas Analysis↗
PubMed1978

Transcutaneous oxygen tension in sick infants.

The clinical usefulness of the transcutaneous O2 electrode was investigated in 30 sick infants; 159 simultaneous measurements of arterial PO2 and transcutaneous PO2 were made. During the comparisons, arterial blood pressure, heart rate, and thoracic impedance were continuously recorded, and skin axillary and environmental temperatures and hematocrit were noted. Despite a wide range of arterial blood pressure and hematocrits, arterial PO2 and transcutaneous PO2 were similar (slope, 0.963), except for 2 groups of sick infants. Some infants with severe, persistent pulmonary hypertension who were receiving an intravascular infusion of tolazoline and infants with mean arterial blood pressures more than 2.5 SD less than the predicted average had values for transcutaneous PO2 that were lower than PO2. The surface O2 electrode is safe and relatively easy to use and provides data that can help in the management of most sick infants.

Blood Pressure↗
PubMed1977

Radioimmunoassay of pulmonary surface-active material in the tracheal fluid of the fetal lamb.

We measured pulmonary surfactant antigen by radioimmunoassay and phospholipid by lipid phosphorus assay in fluid collected during 12-hour periods from the trachea of lambs in utero between 102 and 147 days of gestation. Both phospholipid and antigen were detectable at 114 days and were present at low concentrations until 137 days. The concentrations then increased rapidly and reached 5- to 10-fold higher concentrations before parturition. The ratio of lipid phosphorus to antigen increased approximately 5-fold as the lungs passed from canalicular to alveolar architecture and approximated the adult ratio only during the alveolar stage of development.

Animals↗