Search PubMed⌕ Search

Biomedical subjects

D Humphrey

Publications and source records attributed to D Humphrey.

At least 19 recordsLinked to original sources
PubMed1995

Assessment of mental workload with task-irrelevant auditory probes.

A study was performed to examine the utility of an ERP-based irrelevant probe technique for the assessment of variations in mental workload. Ten highly trained Navy radar operators performed a simulated radar-monitoring task which varied in the density and type of targets to be detected and identified. This task was performed in the presence of a series of irrelevant auditory probes which the radar operators were instructed to ignore. Prior to performing the radar-monitoring task the subjects performed a block of auditory detection trials in which they were asked to respond to the occurrence of one of two low probability tones and ignore the other low probability tone along with a higher probability standard tone. ERPs were recorded from the occurrence of the tones in both the baseline and low and high workload radar-monitoring conditions. The amplitude of the N100, N200, and early and late mismatch negativity (MMN) components decreased from the baseline to the low load radar-monitoring task and again with an increase in the difficulty of the radar-monitoring task. P300 amplitude was sensitive only to the introduction of the radar-monitoring task. These results are interpreted with respect to the phenomenon of attentional capture and suggest that the ERP-based irrelevant-probe technique might prove an effective method for the nonintrusive evaluation of increases in mental workload in complex tasks.

Adult↗
PubMed1995

Rheumatoid nodules of the larynx.

Two unique cases of rheumatoid nodules affecting the larynx are reported. These subcutaneous nodules represent localized laryngeal involvement from autoimmune disorders. The otolaryngologist should be aware of these possibilities as part of the differential diagnosis in the workup of dysphonia.

Adult↗
PubMed1995

A simple, safe and efficient anaesthetic breathing system for universal use in rural environments.

A new simple, safe and efficient anaesthetic breathing system, the Humphrey ADE system, is described for universal use on adults and children. Specialist knowledge is not required as it has been designed to be easy to use. Requiring low fresh gas flows of only three to four litres per minute, the system is efficient for spontaneous, manually assisted respiration, and for controlled ventilation with an automatic ventilator. These multiple functions are dependent on only two positions of a single lever. Easy to follow instructions are permanently engraved on the main block.

Anesthesia, Inhalation↗
PubMed1994

Bioresorbable screws for facial bone reconstruction: a pilot study in rabbits.

Rigid fixation using plates and screws is an accepted mode of repair for facial fractures and osteotomies. To avoid potential complications associated with metal implants, bioresorbable implants are being developed. A study was performed to assess the strength over time of three bioresorbable polymeric screws for facial bone reconstruction. Screws of each polymer type and a titanium control were implanted in the periorbital bones of eight rabbits. Rabbits were euthanized at various time intervals. Pull-out testing and histological analysis were performed. Results showed varying degrees of resorption and screw pull-out strength dependent on time and polymer type, and no change in the control. This study demonstrates that bioresorbable screws can be used in bone, although the optimal choices for human implantation are yet to be determined.

Animals↗
PubMed1993

[Patients cared for at the mental health unit of a primary care office: morbidity study].

Establishing the frequency of mental disorders among patients cared for at the mental health unit of a primary care outpatient clinic of Santiago, Chile, is intended. In this connection, 618 medical records have been screened retrospectively (i.e. a whole universe excepting patients under age 15). A great majority of patients--with an absolute ratio of female patients (88.8%) were referrals from physicians' offices. The most frequent disorders were anxiety disorders and adjustment disorders. Comments are made on (a): the scarcity of referrals from larger general hospitals, and (b) the need for mechanisms apt at an early detection of the most frequent disorders to be set up.

Adjustment Disorders↗
PubMed1991

An international comparison of rhinomanometry between Canada and Japan.

International discussions concerning rhinomanometry have been held but no numerical comparisons have been reported. In an attempt to make international comparisons between different rhinomanometric results, nasal resistances were measured by active posterior rhinomanometry with a head-out body plethysmograph produced in Canada and by active posterior and anterior methods with a Japanese commercial rhinomanometer, and the results were compared. No significant differences were found between measurements obtained from the two types of equipment. It is believed that this study is the first project of international comparison of rhinomanometry.

Adolescent↗
PubMed1990

Screening for early dementia using memory complaints from patients and relatives.

This study examined whether the subjective impression of memory function might differentiate healthy elderly subjects from patients with memory complaints, and whether memory complaints differed between patients with and without a dementing illness. Both self-assessment and relatives' responses on a new memory questionnaire differentiated patient groups from control subjects. The relatives' form measuring deterioration in memory function over time identified dementing individuals from those with non-dementing causes for their memory complaints. Factor analysis indicated that patients' memory complaints correlated with depression rather than objective memory performance, while relatives' ratings correlated with objective memory scores, not depression. Stepwise discriminant function analyses showed that objective memory testing greatly improved specificity but not sensitivity of the subjective memory questionnaire alone.

Aged↗
PubMed1990

Unilateral and bilateral nasal resistances: a supplement.

Three hundred and thirty-four measurements of bilateral and unilateral nasal resistance (at delta P 1.0 cm H2O and by time averaging) in 233 adults were carried out by posterior rhinomanometry with a head-out body plethysmograph. Total nasal resistances, calculated by the equation of Ohm's Law for parallel resistors from measured unilateral resistances, were compared with measured total nasal resistances. The time averaged total nasal resistances calculated by use of Ohm's Law for parallel resistors were closer to direct measurements than resistances at delta P 1.0 cm H2O calculated from the same equation. We attempted to fit calculated total nasal resistance with direct measurements by modification of the equation of Ohm's Law for parallel resistors to T = 0.96[R x L/(R + L)]0.92 in the time averaged nasal resistance and T = 1.07[R x L/(R + L)]0.77 in resistance at delta P 1.0 cm H2O (T: total nasal resistance, R: nasal resistance on the right side, L: nasal resistance on the left side). Calculated total nasal resistances from the above equations agreed closely with direct measurements.

Adult↗
PubMed1989

Computer averaged nasal resistance.

Nasal resistances were measured before and after decongestion of the nasal mucosa by posterior rhinomanometry with a head-out body plethysmograph in 95 adults referred to our nasal airflow laboratory. These resistances were calculated by a time averaging method (1), the equation R = delta P/V at delta P 1.0 cm H2O (2) and R = delta P/V at the point of peak flow (3), and the results were compared. Correspondence between resistances from the time averaging method and those from the equation R = delta P/V at delta 1.0 cm H2O, the equation R = delta P/0.83V1.33 was obtained with statistical significance (P less than 0.001) and it is suggested that the value of resistance from the time averaging method represents transitional airflow. At resistances less than 3.5 cm H2O/L/sec, the time averaging method and the equation R = delta P/V at delta 1.0 cm H2O and at peak flow produced almost identical values. At resistances greater than 3.5 cm H2O/L/sec, the time averaging method produced values equivalent to those from the equation R = delta P/V at peak flow but values from the equation R = delta P/V at delta P 1.0 cm H2O different from the former two methods. The results suggest that nasal resistances from the time averaging method and the equation R = delta P/V at the point of peak flow are appropriate expression of nasal patency.

Adolescent↗
PubMed1987

The use of gastrozepin as a prophylaxis against pulmonary acid aspiration: a new muscarinic receptor antagonist.

Ninety patients presented for elective surgery and were randomly divided into three groups and studied on a double-blind basis to assess the efficacy of gastrozepin, a new muscarinic receptor antagonist, compared to cimetidine and placebo. Gastrozepin 10 mg, cimetidine 200 mg and a placebo were given i.v. on average 90 min prior to surgery. Gastric fluid was aspirated immediately after induction of anaesthesia and the volume and pH measured. The mean gastric fluid volume in the placebo group (19.73 ml) was significantly (P less than 0.02) greater than the mean volume of either the gastrozepin group (12.40 ml) or cimetidine group (12.72 ml). Mean gastric pH's were 4.83 (gastrozepin), 6.39 (cimetidine) and 3.21 (placebo) and each of these means differed significantly from the other two (P less than 0.001). However, the number of patients who had a gastric juice volume of more than 25 ml and a pH of less than 2.5 in each of the three groups: gastrozepin, cimetidine and placebo, were 1, 0, and 8, respectively.

Adult↗
PubMed1986

Single lever Humphrey A.D.E. low flow universal anaesthetic breathing system. Part I: Comparison with dual lever A.D.E., Magill and Bain systems in anaesthetized spontaneously breathing adults.

The single lever Humphrey A.D.E. anaesthetic system, in both coaxial and parallel (non-coaxial) forms, has recently been introduced. In principle the system offers efficient "universal" function by combining the advantages of Mapleson A, D and E systems. A within-patient comparison of its function in the Mapleson A mode (lever up) in spontaneously-breathing anaesthetized subjects was made to that of the original two lever A.D.E., the Magill (Mapleson A) and the Bain (Mapleson D) systems. The coaxial and parallel single lever A.D.E. systems functioned identically to each other and to the original two lever A.D.E. system, a mean fresh gas flow (FGF) of 51 ml X kg-1 X min-1 causing minimal rebreathing. Under identical conditions, the mean FGF required to just cause rebreathing increased to a mean of 71 ml X kg-1 X min-1 and 150 ml X kg-1 X min-1 with the Magill and the Bain systems respectively. With the single lever system, the switch to its Mapleson E mode for controlled ventilation involves the selection of the only alternative lever position (lever down) without further adjustment. The function and practical advantages in this E mode are presented in Part II.

Adolescent↗