PubMed Health⌕ Search

Biomedical subjects

S B Baker

Publications and source records attributed to S B Baker.

16 recordsLinked to original sources
PubMed1991

Pneumococcal bacterial tracheitis.

Bacterial tracheitis is an uncommon cause of acute respiratory distress in children. The authors present a case of bacterial tracheitis in a 6-year-old girl caused by an unusual pathogen, Streptococcus pneumoniae. Her clinical presentation and radiographic findings are typical for an older child. Management of this case involved endotracheal intubation, although a review of the literature suggests that airway management can vary with age and size of the tracheal lumen. The microbiology of bacterial tracheitis shows a predominance of Staphylococcus and Streptococcus reported previously, with only three prior reported cases of Pneumococcus.

Adolescent↗
PubMed1991

Propofol: effective dose and induction characteristics in unpremedicated children.

The induction dose, induction characteristics, and cardiovascular and respiratory effects of propofol were studied in 90 unpremedicated children 3-12 yr old. Propofol in a dose of 1-3 mg.kg-1 was injected in an antecubital vein over 10-30 s. Successful induction was defined by loss of eyelash reflex occurring within 50 s of the conclusion of propofol injection and followed by subsequent acceptance of face mask without excessive movement. The effective dose of propofol resulting in loss of eyelash reflex in 50% (ED50) and 95% (ED95) of children were 1.3 (1.1-1.4) and 2.0 (1.7-2.6) mg.kg-1 (95% confidence interval). The corresponding ED50 and ED95 for a successful induction that included acceptance of face mask were 1.5 (1.3-1.7) and 2.3 (2.1-3.0), respectively. There was a 6.6% incidence of mild to moderate pain on injection and a 12.7% incidence of involuntary movement. Apnea (cessation of breathing greater than 20 s) was seen in 21% of patients. Blood pressure decreased by more than 20% of baseline value in 48% of patients who received halothane (1-3%) after the bolus injection of propofol. It is concluded that propofol is an effective induction agent in children. A dose of 2.5-3.0 mg.kg-1 is recommended to ensure a smooth transition to an inhalational maintenance technique. The use of antecubital veins is associated with a low incidence of pain on injection.

Anesthesia, Intravenous↗
PubMed1989

Arousal and cardiopulmonary responses to hyperoxic hypercapnia in lambs.

Experiments were done to investigate the arousal and cardiopulmonary responses to hyperoxic hypercapnia in 8 lambs. Each lamb was anaesthetized and instrumented for recordings of electrocorticogram, electro-oculogram, nuchal and diaphragm electromyograms and measurements of arterial blood pressure and haemoglobin oxygen saturation. No sooner than 3 days after surgery, measurements were made in quiet sleep and active sleep during control periods when the animal was breathing 21% oxygen and during experimental periods of hyperoxic hypercapnia when the animal was breathing 10% carbon dioxide and 30% oxygen. Hyperoxic hypercapnia was terminated during each epoch by returning the inspired gas mixture to 21% oxygen once the animal aroused from sleep. Arousal occurred from both sleep states during hyperoxic hypercapnia but was delayed in active sleep compared to quiet sleep (active sleep 58 +/- 17 s; quiet sleep 21 +/- 10 s; mean +/- 1SD). There were no significant changes in heart rate or blood pressure during hyperoxic hypercapnia before arousal. However, respiratory rate and diaphragm electrical activity did increase during hyperoxic hypercapnia before arousal. Thus, our data provide evidence that hypercapnia can initiate arousal from sleep in young lambs. The mechanisms responsible for this response are yet to be determined.

Animals↗
PubMed1988

Heart rate response to arousal and lung inflation following upper airway obstruction in lambs.

Experiments were done to determine the influence of arousal from sleep and lung inflation on heart rate following upper airway obstruction in lambs. Ten lambs were anesthetized and instrumented for recordings of electrocorticogram, electro-oculogram, nuchal and diaphragm electromyograms, and measurements of systemic arterial blood pressure and arterial hemoglobin oxygen saturation (fiberoptic catheter oximeter). A tracheotomy was done and a fenestrated tracheostomy tube was placed in the trachea. A 5F balloon-tipped catheter was inserted into the tube so that the airway could be obstructed by inflating the balloon. No sooner than 3 days after surgery, measurements were made during a control period of normal tidal respiration, during upper airway obstruction immediately before arousal, during upper airway obstruction immediately after arousal, and following the first lung inflation. A total of 39 epochs of quiet sleep and 33 epochs of active sleep were obtained. Heart rate and oxygen saturation decreased (p less than 0.05) during upper airway obstruction in quiet sleep and active sleep. Arousal from sleep did not significantly alter heart rate during continued upper airway obstruction. However, heart rate quickly returned toward control levels following the first lung inflation despite continued oxygen desaturation. These results provide evidence that the abrupt tachycardia following an apneic episode is related to lung inflation rather than to the arousal response per se.

Airway Obstruction↗
PubMed1987

Invasive aspergillosis in children.

Aspergillosis may complicate the course of the child in an immunocompromised state. When sinus or pulmonary infections present in immunocompromised children, one third of these patients are diagnosed accurately premortem as resulting from aspergillosis and two thirds remain undiagnosed. Mortality remains quite high, despite prompt treatment. Four children in our hospital during the last 4 years have had invasive aspergillosis presenting other than sinus or pulmonary infections. Each presented with extensive soft tissue infection. Three presented after traumatic devascularizing injuries to the leg in which massive soil and fecal contamination occurred. One child presented with absolute neutropenia secondary to treatment of acute lymphocytic leukemia. The child had a chest wall lesion develop at the site of an EKG electrode. All patients had a punctate black skin lesion with a halo of intense erythema surrounded by a zone of blanching. These lesions rapidly expanded. Initial extensive debridement of the lesions, combined with systemic chemotherapy with amphotericin B failed to halt the progression of the disease. Histology showed vascular invasion with hyphal forms. Each patient then responded well to radical debridement (three hemipelvectomies and one chest well resection). The child in an immunocompromised state who develops a red papule, then a black eschar with surrounding erythema, should have immediate biopsy that can easily demonstrate the characteristic hyphal forms. Early radical surgical debridement and antifungal therapy can be lifesaving. The initial debridement should include tissues well beyond any apparent involvement.

Amphotericin B↗
PubMed1987

Epidemiology of sarcoidosis in the Isle of Man--1: A case controlled study.

A case controlled study of 96 cases of sarcoidosis has been carried out in the Isle of Man. Age and sex matched controls were selected at random from the pathology and radiology records, which cover 85% of the resident population, and a second control group was drawn from a tuberculosis register. Special efforts were made to achieve a high level of ascertainment. In this study most cases occurred in young adults. It affected the sexes equally and occurred more frequently in the indigenous Manx population. Thirty eight cases (39.6%) had been in contact with the disease before diagnosis, compared with two (1.2%) of the combined controls. These contacts included members of the same household, colleagues at work, and close friends. A bias may have been introduced as patients would inevitably be more aware of the disease and be more likely to mention previous contact than the controls. Nevertheless, the evidence is considered to support the view that sarcoidosis is a communicable disease.

Adult↗
PubMed1987

Epidemiology of sarcoidosis in the Isle of Man--2: Evidence for space-time clustering.

The case-control test for space-time clustering developed by Pike and Smith was applied to 96 cases of sarcoidosis diagnosed in the Isle of Man from 1962 to 1983. There were significantly more links between cases separated by time intervals of less than 10 years and distances of less than 100 metres than between the others. Analysis of the type of links indicated that clusters consisted of pairs whose contact was by place of residence or work. More linked cases were diagnosed less than three years apart than would be expected by chance. These findings lend support to the idea that sarcoidosis is a communicable disease.

England↗
PubMed1987

Effects of hyperoxia on the arousal response to upper airway obstruction in lambs.

Experiments were done to investigate the effects of increased inspired oxygen on the arousal response from sleep to upper airway obstruction in 10 newborn lambs. Each lamb was anesthetized and instrumented for recordings of electrocorticograms, electrooculogram, nuchal and diaphragm electromyograms, and measurements of systemic arterial blood pressure and oxygen saturation (fiberoptic catheter oximeter). A tracheotomy was performed and a fenestrated tracheostomy tube was placed in the trachea. A 5F balloon tipped catheter was inserted into the tube so that airflow could be obstructed by inflating the balloon. No sooner than 3 days after surgery, measurements were made during a control period and during an experimental period of upper airway obstruction; the inspired oxygen fraction was alternated hourly between 0.21 and 0.60. A total of 57 epochs of quiet sleep and 58 epochs of active sleep was obtained in eight lambs. Arousal was significantly delayed (p less than 0.005) during active sleep (21 +/- 6 s; mean +/- 1 SD) compared to quiet sleep (7 +/- 2 s) in room air. Increased inspired oxygen significantly delayed arousal (p less than 0.05) during active sleep (47 +/- 25 s), but had little effect on arousal in quiet sleep (10 +/- 4 s). These results provide evidence that arousal from active sleep following upper airway obstruction in lambs is primarily initiated by a decrease in arterial oxygen. However, arousal from quiet sleep following upper airway obstruction in lambs appears to be initiated by other stimuli.

Airway Obstruction↗
PubMed1987

Arousal from sleep during rapidly developing hypoxemia in lambs.

Arousal is an important protective response that may prevent severe hypoxemia and death during sleep. However, very little is known about arousal from sleep in response to respiratory stimuli in newborns. Experiments were therefore done to investigate the arousal response from sleep to rapidly developing hypoxemia in eight lambs. Each lamb was anesthetized and instrumented for recordings of electrocorticogram, electrooculogram, nuchal and diaphragm electromyograms, and measurements of arterial hemoglobin oxygen saturation. A tracheotomy was done and a tracheostomy tube placed in the trachea so that the fraction of inspired oxygen could be changed quickly. No sooner than 3 days after surgery, measurements were made in quiet sleep and active sleep (AS) during 30-s control periods when the animals were breathing 21% oxygen and during experimental periods of hypoxemia when the animals were breathing either 10, 5, or 0% oxygen in nitrogen. During quiet sleep, arousal occurred at similar arterial hemoglobin oxygen saturations (81 +/- 6% on 10% O2, 80 +/- 5% on 5% O2 and 83 +/- 5% on 0% O2) suggesting that arousal was independent of the rate of change of arterial oxygen. However, during AS arousal occurred at different arterial hemoglobin oxygen saturations (76 +/- 6% on 10% O2, 55 +/- 11% on 5% O2, and 44 +/- 17% on 0% O2) suggesting that arousal was dependent on the rate of change of arterial oxygen. During some epochs of AS, electrocortical signs of cerebral hypoxia and primary apnea occurred before arousal. These data provide evidence that arousal from quiet sleep in response to hypoxemia occurs once an arousal threshold has been reached.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Incidence of sarcoidosis in the Isle of Man.

The incidence of sarcoidosis in a clearly defined island community has been determined in a seven year study. Special efforts were made to identify all cases, including those presenting to their general practitioners with only minor symptoms. A mean incidence of 14.7 per 100 000 per annum has been found in the years 1977-83 compared with an annual incidence of 3.5 per 100 000 in the preceding 15 years, when no specific attempts were made to identify sufferers from sarcoidosis. The lower figure is similar to the reported incidence in the United Kingdom and the difference is considered to be due to increased detection of cases during the study period. These findings suggest that a large proportion of cases of sarcoidosis in a general population may not be recorded in a registration system.

Adolescent↗
PubMed1979

Late onset systemic lupus erythematosus.

This study describes the clinical and laboratory features and the natural history of 31 patients with late onset (in the sixth decade or later) systemic lupus erythematosus (SLE). Patients with late onset SLE constitute a distinct subset of the general lupus population that accounts for approximately 12 per cent of the cases. Advanced age modifies the expression of SLE in terms of clinical presentation (pleuritis and/or pericarditis are the most common presenting manifestations) and pattern of organ involvement (pulmonary abnormalities are more common, whereas lymphadenopathy, Raynaud's phenomenon, neuropsychiatric disease, alopecia and skin rash are less common). Because SLE is not usually considered to be a disease that affects the elderly, and because the pattern of SLE in the older age group may differ substantially from the seen in younger patients, there is often a delay in diagnosis (median of 10 months, with a delay of over one year in 32 per cent of patients). In light of the high incidence of steroid complications in older patients (40 per cent in our series), and because these patients with SLE have a relatively good prognosis (five year survival of 92.3 per cent; nine year survival of 83.1 per cent), therapy should be more conservative in late onset SLE.

Aged↗
PubMed1978

Unusual renal manifestations of Wegener's granulomatosis. Report of two cases.

Two patients with previously undescribed renal manifestations of Wegener's granulomatosis are described. A 24 year old man, who presented with typical necrotizing granulomatous sinus disease and cavitary pulmonary lesions, had multiple bilateral renal arterial aneurysms demonstrated angiographically. One of these aneurysms ruptured, leading to a massive perinephric hematoma. The bleeding artery was successfully occluded with Gelfoam embolization, thereby obviating the need for nephrectomy. A 60 year old woman presented with glomerulonephritis and mononeuritis multiplex two years before the development of classic necrotizing granulomatous inflammation of her sinuses and nose, along with pulmonary nodules. In addition, her left ureter became obstructed due to necrotizing vasculitis of the periureteral vessels. Both patients responded dramatically to cyclophosphamide therapy. The diagnosis of Wegener's granulomatosis should be considered in patients who present with multiple renal aneurysms, a spontaneous perinephric hematoma, necrotizing glomerulitis or ureteral obstruction due to vasculitis, even though the characteristic granulomatous respiratory involvement may be absent at that time. It is important to recognize these unusual renal manifestations as features of Wegener's granulomatosis because of the therapeutic efficacy of cytotoxic immunosuppressive agents in this disease.

Adult↗