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Biomedical subjects

N Carroll

Publications and source records attributed to N Carroll.

At least 37 records · Page 2Linked to original sources
PubMed1995

Excimer laser filtration surgery.

PURPOSE: In order to remove precisely scleral tissue overlying Schlemm's canal with minimal trauma as an outpatient procedure under local anesthetic, we used a VisX Twenty/Twenty excimer laser. METHODS: We performed excimer laser filtration in three enucleated pig eyes, seven enucleated human eyes, and seven eyes of seven patients with severe glaucoma. Precise ablation to Schlemm's canal was confirmed by scanning electron microscopy in the enucleated eyes. For the patients, a local anesthetic was used, and a custom-made holder was used to mobilize the conjunctiva and fix the eye. RESULTS: A functional sclerostomy was obtained with 1,780 to 5,965 pulses, using a 2 x 1-mm slit. In our mean follow-up of nine months (range, six to 12 months) the excimer laser filtration technique achieved controlled filtration in five of seven patients and minimized conjunctival trauma. One patient subsequently underwent cataract extraction. CONCLUSIONS: This study indicates that excimer laser filtration is an effective technique for achieving filtration in glaucoma. It may reduce the complications of glaucoma filtration surgery, particularly the incidence of shallow anterior chamber postoperatively, as it leaves the trabecular meshwork intact.

Aged↗
PubMed1995

Excimer laser lamellar keratoplasty.

PURPOSE: To evaluate a procedure using the excimer laser to perform lamellar keratoplasty to treat deep corneal scars in the central optical zone. To determine if excimer laser can safely prepare a smooth surface for the host bed and the donor button, assess the interface opacity and evaluate the effects of the ablation on the recipient's endothelial surface with the deeper ablation. METHODS: Nineteen rabbits underwent an excimer laser lamellar keratoplasty in one eye. The rabbits were followed for 9 to 12 weeks until they were sacrificed. RESULTS: Little opacity developed at the graft-host interface and scanning electron microscopy of the endothelial surface showed little difference between the treated and untreated areas or the endothelium of the untreated eyes. CONCLUSIONS: Our results suggest that the use of the excimer laser to treat corneas with deep stromal scars and normal endothelium is feasible. However, we have not proved that this technique will give a better result than conventional lamellar dissection methods.

Animals↗
PubMed1993

Exercise performance and fatiguability in patients with chronic fatigue syndrome.

To examine the role of delay in recovery of peripheral muscle function following exercise in the fatigue experienced by patients with the chronic fatigue syndrome (CFS) and to examine the influence of effort perception in limiting exercise performance in these patients, a study was carried out on a group of twelve patients with chronic fatigue syndrome and 12 sex and age-matched sedentary control subjects. Symptom limited incremental cycle exercise tests including measurements of perceived exertion were performed followed by examination of the contractile properties of the quadriceps muscle group for up to 48 hours. Muscle function was assessed by percutaneous electrical stimulation and maximum voluntary contractions. Muscle function at rest and during recovery was normal in CFS patients as assessed by maximum isometric voluntary contraction, 20:50 Hz tetanic force ratio and maximum relaxation rate. Exercise duration and the relationship between heart rate and work rate during exercise were similar in both groups. CFS patients had higher perceived exertion scores in relation to heart rate during exercise representing a reduced effort sensation threshold of 3.2 units on an unmodified Borg scale in CFS patients. Patients with chronic fatigue syndrome show normal muscle physiology before and after exercise. Raised perceived exertion scores during exercise suggest that central factors are limiting exercise capacity in these patients.

Adolescent↗
PubMed1993

The structure of large and small airways in nonfatal and fatal asthma.

Asthma is characterized by excessive airway narrowing and airway wall inflammation. In cases of fatal asthma, increased thickness of the airway wall is observed and may account for excessive airway narrowing when smooth muscle contracts. This study was undertaken to examine airway dimensions in large and small airways in both fatal and nonfatal cases of asthma. Airway wall areas (total, inner, and outer relative to smooth muscle layer), epithelial integrity, smooth muscle shortening, and the areas of smooth muscle, cartilage, and mucous glands were compared in transverse sections of large and small airways of subjects dying of asthma (fatal asthma, n = 11), those dying suddenly of nonrespiratory diseases and having a definite history of asthma (nonfatal asthma, n = 13), and those dying suddenly without any history of respiratory illness (control, n = 11). Airways were grouped by size using the basement membrane perimeter for comparison. All areas were expressed as areas per millimeter of basement membrane. In cartilaginous airways, the cases of fatal asthma had greater (p < 0.05) total wall, inner wall, outer wall, smooth muscle, mucous gland and cartilage areas than did control and nonfatal cases. The inner wall area was greater in the fatal and nonfatal cases than in the control cases (p < 0.05) in the small cartilaginous airways and membranous bronchioles (MB). In small MB (perimeter < 2 mm), the total and outer wall areas were greater (p < 0.05) in cases of fatal and nonfatal asthma than in control cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Colonic involvement in Fabry's disease.

The case of a 54 year old man with Fabry's disease and extensive jejunal and colonic diverticulosis causing colonic stricture is presented. Histological examination of the resected colon revealed evidence of ceramide trihexose deposition in the myenteric nerve plexus. Colonic involvement in Fabry's disease has not been reported before.

Colon, Sigmoid↗
PubMed1991

Domiciliary investigation of sleep-related hypoxaemia in Duchenne muscular dystrophy.

In Duchenne muscular dystrophy (DMD) nocturnal oxygen desaturation occurs during rapid eye movement (REM) sleep. Polysomnography, which requires hospital admission, will detect sleep-related breathing abnormalities. In order to avoid the inconvenience of hospital admission for the disabled patient, we investigated overnight oxygenation in ten boys with DMD by domiciliary oximetry. In four boys the results of oximetry were compared with those of a polysomnographic recording. The "repeatability" of domiciliary oximetry was assessed in six boys by performing oximetry on two non-consecutive nights. Older boys with DMD may develop a cardiomyopathy. In order to assess cardiac rhythm and ST segment changes we performed simultaneous Holter monitoring and oximetry in seven boys with overnight hypoxaemia. Six of the initial ten boys studied demonstrated episodic nocturnal hypoxaemia and there was a strong correlation between minimum oxygen saturation overnight and daytime arterial oxygen and carbon dioxide tensions (PaO2 r = 0.89; PaCO2 r = -0.87). Despite adequate REM time during polysomnography, greater oxygen desaturation was found during domiciliary oximetry. No difference was found in the severity of desaturation recorded in the boys who were studied on two separate occasions. Five boys demonstrated marked heart rate variation during hypoxaemic episodes and more serious arrhythmias occurred overnight in the three most hypoxaemic boys. Domiciliary oximetry is a simple, repeatable method of assessing overnight oxygenation and compares well with polysomnography. In boys with advanced DMD and severe nocturnal hypoxaemia, 24 h electrocardiographic monitoring may detect potentially life-threatening arrhythmias.

Adolescent↗
PubMed1990

Nocturnal oxygen desaturation in patients using long-term oxygen therapy for chronic airflow limitation.

Nocturnal oxygen desaturation in patients receiving long-term oxygen therapy is described despite adequate daytime oxygenation (PaO2 greater than 8 kPa). Domiciliary oximetry overnight was performed on ten patients receiving long-term oxygen treatment for chronic airflow limitation: six patients were well saturated throughout the night with a fall in SaO2 to below 90% for only 1% of the monitoring time; four showed significant desaturation with a fall in SaO2 to below 90% for periods of 15-47% of the monitoring time.

Aged↗
PubMed1990

Role of nocturnal hypoxaemia in the genesis of systemic hypertension.

Two groups of patients with nocturnal arterial oxygen desaturation were compared. The degree of nocturnal oxygen desaturation, as reflected by the percentage of total sleep time spent with an oxygen saturation less than 90 and 80%, was similar in patients with the obstructive sleep apnoea syndrome (OSAS) and in those with nocturnal hypoventilation (NH) secondary to restrictive chest wall disease. Systemic hypertension was present in 16 of the 24 OSAS patients but in only 6 of the 24 with NH (p less than 0.005). Multiple regression analysis demonstrated that this difference remained significant even after adjustment for age, sex, weight and history of smoking. It is likely that factors other than nocturnal hypoxaemia are important in the aetiology of systemic hypertension in patients with sleep-related breathing disorders.

Female↗
PubMed1990

The use of protriptyline for respiratory failure in patients with chronic airflow limitation.

Treatment of nocturnal hypoventilation in patients with restrictive chest wall disease and respiratory failure, results in improved daytime arterial blood gas tensions, increase in functional ability and longer survival. Success has been achieved with the use of protriptyline which reduces the duration of rapid eye movement (REM) sleep during which nocturnal hypoventilation occurs. Eighteen patients with severe chronic airflow limitation (CAL), took part in a randomized, double-blind, crossover trial of protriptyline and placebo. Seventeen patients completed the study. The use of protriptyline was associated with a fall in the median percentage of total sleep time spent in REM from 16 to 8.8% (p less than 0.01). This was associated with a reduction in the median daytime arterial carbon dioxide tension from 6.4 kPa (range 5.2-8.5 kPa) to 5.8 kPa (range 5.0-8.1 kPa) (p less than 0.01); increased respiratory muscle strength (p less than 0.05), and increased six minute walking distance from a median of 258 m (range 58.5-585 m) to 275 m (range 171-598 m) (p less than 0.02). We found pharmacological treatment of REM-related nocturnal hypoventilation in patients with CAL to be effective, but anticholinergic side-effects, particularly in older male patients, might preclude long-term treatment.

Adult↗
PubMed1989

Tuberculous retropharyngeal abscess producing respiratory obstruction.

Oropharyngeal tuberculosis is a rare presentation of the disease even in the presence of extensive pulmonary tuberculosis. A case is described in which a retropharyngeal abscess, causing stridor and threatening respiratory obstruction, was the only manifestation of Mycobacterium tuberculosis infection.

Abscess↗
PubMed1989

Effect of protriptyline on ventilatory responses to hypercapnia and asphyxia in normal subjects.

A double-blind crossover study was undertaken to assess the effect of protriptyline on ventilatory responses in normal subjects. Seven subjects received in random order placebo, 10 mg and 20 mg protriptyline daily for 2 weeks. Measurements of hypercapnic ventilatory response (HCVR) and asphyxial hypoxic ventilatory response (HVR) were made before treatment, 6-8 h after the first dose, and after 2 weeks treatment. Mean HCVR and HVR following 10 mg and 20 mg protriptyline did not differ significantly from measurements on placebo, neither for the single dose study or after 2 weeks.

Adult↗
PubMed1988

Intermittent positive pressure ventilation by nasal mask: technique and applications.

Intermittent positive pressure ventilation delivered non-invasively through a well-fitting nasal mask has been used to control nocturnal hypoventilation in three patients with severe, combined cardiorespiratory and skeletal disease. The advantages of this approach to domiciliary ventilation are described and the requirements of the ventilator are defined.

Adult↗
PubMed1988

Recognition of intoxication by alcohol counselors.

Recent studies have found that police officers, bartenders, social drinkers, and trained interviewers are often unable to recognize when others are intoxicated. The present two studies were conducted to evaluate: (a) the recognition ability of alcohol counselors compared to mental health counselors, and (b) the recognition ability of less-experienced versus more-experienced alcohol counselors. Subjects viewed four videotapes of a 21-year-old male engaged in simulated counseling interviews after he was given drinks containing alcohol to achieve one of four target Blood Alcohol Level (BAL) goals: .00%, .05%, .10%, .15%. Results indicated that alcohol counselors were not uniformly more accurate than mental health therapists, nor were more-experienced alcohol counselors uniformly more accurate than less-experienced alcohol counselors at recognizing intoxication or estimating BAL. In addition, subjects generally underestimated the target's sober-intoxicated status and BAL when he was given alcohol, but almost every subject recognized that the target was at least moderately intoxicated when his BAL was .15%.

Adult↗
PubMed1988

Use of negative pressure ventilation to facilitate the return of spontaneous ventilation.

Negative pressure ventilation was used to facilitate the return of spontaneous ventilation in 10 patients with severe, chronic respiratory disability. All patients had required tracheal intubation and intermittent positive pressure ventilation, and conventional weaning techniques had failed. Details of the method are described. It permits extubation before spontaneous ventilation can be sustained indefinitely and thus assists the return of normal speech, sleep pattern and nutrition. The lack of flexible control of ventilatory variables and absence of access to the trachea for sputum clearance limit its widespread application.

Adolescent↗
PubMed1988

Control of nocturnal hypoventilation by nasal intermittent positive pressure ventilation.

Ten patients with respiratory failure and nocturnal hypoventilation were treated for three to nine months by nasal intermittent positive pressure ventilation. Four patients had chronic obstructive lung disease (median FEV1 19% predicted) and six restrictive chest wall disorders (median FVC 25% predicted); eight of the patients also had cardiac failure. The median daytime arterial oxygen tension, measured before and after at least three months' treatment, increased from 6.2 (range 5.4-9.6) to 9.1 (7.1-9.8) kPa in those with restrictive disease (p less than 0.05), and from 6.0 (5.7-6.5) to 7.1 (6.3-7.7) kPa in the four with airflow limitation (NS). Median values for arterial carbon dioxide tension over the same time fell from 8.2 (range 6.7-9.8) to 6.5 (6.0-6.9) kPa in the group with restrictive disease (p less than 0.05) and from 8.2 (7.0-9.2) to 7.1 (4.9-7.7) kPa in those with airflow limitation (p less than 0.02). Total sleep time while patients were using nasal positive pressure ventilation varied from 155 to 379 (median 341) minutes, and included 4-26% rapid eye movement sleep (median 14%). The percentage of monitored time during the night in which the arterial oxygen saturation was less than 80% fell from a median (range) of 96 (3-100) to 4 (0-9) in the six patients with restrictive disease and from 100 (98-100) to 40 (2-51) in those with airflow limitation. There were no changes in spirometric values but exercise tolerance improved in all patients. The technique may prove an acceptable alternative to long term domiciliary oxygen therapy in selected patients.

Adult↗