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Biomedical subjects

A Pick

Publications and source records attributed to A Pick.

At least 19 recordsLinked to original sources
PubMed1992

The effect of selective decontamination of the digestive tract on gastrointestinal enterococcal colonization in ITU patients.

OBJECTIVE: The effect of selective decontamination of the digestive tract (SDD) on Intensive Therapy Unit (ITU)-acquired enterococcal infection and colonization was studied. Changes in the predominant species isolated and resistance patterns to antimicrobial agents were also studied. DESIGN: Three groups were investigated: historical control (HC), contemporaneous control (CC) and patients receiving SDD (topical polymyxin, amphotericin B and tobramycin throughout ITU stay with intravenous ceftazidime for the first 3 days only). SETTING: Adult general ITU with 7 beds. PATIENTS: Patients with a nasogastric tube in situ and who were likely to remain in ITU for 48 h or longer were recruited. RESULTS: Enterococcal infections occurred in 3 of 84 HC patients and 2 of 91 CC patients. There were no unit-acquired enterococcal infections in the SDD group. There were 140 episodes of enterococcal colonization occurring in 112 patients, with significantly more in the SDD and CC groups (p < 0.05. There were no significant differences in antibiotic sensitivities between the three groups. Enterococcus faecalis was the most frequently isolated species. CONCLUSION: SDD does not predispose to enterococcal infection but does encourage colonization in patients receiving the regimen and other patients in ITU at the same. There is a complex interaction of factors which influence faecal flora and the likelihood of patients becoming colonized or infected with enterococci.

Administration, Buccal↗
PubMed1992

A controlled trial of selective decontamination of the digestive tract in intensive care and its effect on nosocomial infection.

Nosocomial infection is a major problem in intensive therapy units (ITUs) and a significant cause of mortality. Selective decontamination of the digestive tract (SDD) has been advocated as a means to reduce ITU morbidity and mortality. Ninety-one patients in a general ITU underwent SDD, consisting of topical polymyxin E, tobramycin and amphotericin B administered throughout the unit stay together with parenteral ceftazidime for the first three days, and were compared with 84 historical and 92 contemporaneous control patients who were treated conventionally. Twenty-seven historical and 32 contemporaneous control patients developed unit-acquired infections, in comparison with only three patients in the SDD group (P less than 0.01). Mortality in the SDD group (36%) was not significantly different from that in the other two groups (historical control 40%, contemporaneous control 43%). Screening specimens revealed a significantly higher rate of colonization with resistant Acinetobacter spp. in the contemporaneous control than in the other two groups of patients; infection caused by resistant bacteria did not occur. SDD did not lead to a significant reduction in the use of systemically-administered antibiotics when compared with either control group. SDD may be used selectively in an ITU without ill effects on those patients not receiving SDD; nevertheless, microbiological monitoring is needed to detect emergence of resistant bacteria in the unit.

Adolescent↗
PubMed1979

Effects of stable and changing rates and premature ventricular beats on transient tachycardia-, pseudobradycardia-, and bradycardia-dependent bundle branch block alternans.

New circumstances under which bundle block (BBB) alternans may appear or disappear are described. 1) Tachycardia-dependent as well as bradycardia-dependent BBB alternans may begin after constant BBB is interrupted by a premature ventricular beat. Tachycardia- and bradycardia- dependence may be differentiated by the shape of the first beat after the pause. 2) When BBB alternans disappears during a constant ventricular rate, tachycardia-dependent BBB alternans changes to persistent normal or more normal intraventricular conduction, whereas bradycardia-dependent BBB alternans changes to a persistently greater degree of BBB. 3) BBB alternans appears to be tachycardia- or pseudobradycardia-dependent in relation to the cycle length and antegrade and retrograde refractory periods in the involved bundle branch. 4) BBB alternans may be recognized during persistent irregular ventricular action in atrial fibrillation. Here the recognition of BBB alternans depends upon the sequence of contours as well as upon the cycle lengths.

Bradycardia↗
PubMed1978

A characteristic precordial repolarization abnormality with intermittent left bundle-branch block.

We reviewed electrocardiograms of 23 patients with intermittent left bundle-branch block. A characteristic electrocardiographic pattern consisting of right and mid-precordial deep symmetrical T-wave inversions was detected during normal conduction in 19 of the 23. Of the seven patients who had cardiac catheterization, only two had findings suggestive or organic heart disease and only one had significant obstructive coronary disease. Thus we conclude that patients with intermittent left bundle-branch block frequently have T-wave inversions in right and mid-precordial leads during normal conduction that do not necessarily reflect coronary disease. These T-wave changes are similar to those after termination of chronic right ventricular pacing (left bundle-branch pattern), suggesting that both patterns of abnormal ventricular activation can produce abnormal repolarization when activation returns to normal.

Adult↗
PubMed1977

Electrophysiological and anatomical observations on the heart of the African lungfish.

Electrophysiological and histological observations were made on the heart of the African lungfish. Impulse origin and propagation were studied using simultaneously recorded epicardial and pericardial electrograms. The primary pacemaker site in the lungfish was found to be at the sinus venosus at its junction with the left cardinal vein. Under a variety of circumstances, pacemaker function shifted to other sites. In response to stress, probably under vagal influence, the regular and rapid sinus venosus rate was generally superseded by an irregular and slower atrial pacemaker. Heart rate and sinoatrial and atrioventricular conduction times varied with changes in temperature [Q10=3.77, 2.55, and 5.46, respectively]. Although alterations in impulse formation and conduction did occur, the site of impulse formation and the patterns of conduction between heart chambers were usually fixed, implying the existence of an organized conduction system. Nonetheless, extensive histological study failed to disclose either organized nodal structures or specialized conduction pathways.

Africa, Central↗
PubMed1977

Tachycardia and bradycardia-dependent bundle branch block alternans: clinical observations.

Eleven patients with tachycardia-dependent, bradycardia-dependent, or "pseudobradycardia-dependent" bundle branch block (BBB) alternans were studied. This classification is based on the following criteria: 1) When alternans is initiated by a sudden acceleration in ventricular rate, or it appears with aberration of the second beat after a pause, the alternans is tachycardia-dependent and results from a 2:1 bidirectional block in the affected bundle branch. 2) When alternans begins with the aberrant complex terminating a pause it is bradycardia-dependent; such an alternans results from alternating bundle branch cycle lengths and refractoriness, possibly produced by alternating transseptal retrograde penetration of the affected bundle branch. 3) In cases referred to as "pseudobradycardia-dependent BBB" alternans, a change from alternans to persiscardia-dependent BBB" alternans, a change from alternans to persistent BBB occurs as the cycle lengthens; however, the disappearance of BBB with further increase of the cycle length proves the tachycardia-dependence of the conduction defect.

Aged↗
PubMed1976

Parasystole and its variants.

Various mechanisms that cause deviations from the classical manifestations of a parasystolic rhythm are reviewed and illustrated by selected clinical electrocardiograms. They consist of: (1) Transient or continued fixed coupling of the ectopic beats, due to (a) synchronization of basic and parasystolic rhythms; (b) reversed coupling of the basic to the ectopic rhythm (unidirectional protection); (c) the operation of supernormal phase of excitability; and (d) intermittent parasystole, due to gap in the protection of the parasystolic center. (2) Irregularities in response to a regular parasystolic discharge may be caused by a second degree exit block, usually of Mobitz type II, rarely of type I. An electrophysiologic basis for the emergence and maintenance of parasystolic rhythms appears to be abnormal states of spontaneous diastolic (phase 4) depolarization in otherwise latent subsidiary cardiac pacemakers.

Arrhythmia, Sinus↗
PubMed1976

Concealed intraventricular conduction in the His bundle electrogram.

Multiple areas of concealed intraventricular conduction are deduced on the basis of aftereffects observed in His bundle recordings. Electrocardiograms and His bundle recordings are presented from two patients with unstable bilateral bundle branch block, the instability of which depended on the interval at which ventricular depolarization was initiated by sinus or paced impulses. This circumstance allows postulation of 1) concealed transseptal retrograde penetration of the left bundle branch system; 2) concealed transseptal retrograde penetration of the right bundle branch system; 3) alternate beat Wenckebach phenomenon with two areas of block in the bundle branch system with concealed penetration of the proximal area; 4) concealed re-entry in the right bundle branch system during an H-V Wenckebach cycle with resetting of the sequence of 2:1 H-V block and return of the re-entry wave to the A-V node causing subsequent A-H block; 5) proximal 2:1 block and distal Wenckebach block producing only two consecutively blocked beats; and 6) infrahisian Wenckebach block with changes both in A-V conduction and QRS contour.

Aged↗
PubMed1975

The incidence of typical and atypical A-V Wenckebach periodicity.

The classic pattern of the typical WP's consists of (1) progressive lengthening of the P-R intervals with the largest increment occuring in the second conducted beat, (2) progressive decrease in P-R increment which accounts for the progressive shortening of successive R-R intervals, and (3) the pause produced by the nonconducted P-wave is less than two P-P intervals. In 45 patients with atrial pacing-induced Wendkebach periods of A-V conduction, the structure of these was studied with His bundle recordings. Of the 128 periods analyzed exceeding 3:2 A-V conduction ratios, 66 per cent were atypical. In 24 patients with spontaneous WP's of A-V conduction, the electrocardiographic records were studied. Of the 98 periods analyzed exceeding 3:2 A-V conduction ratios, 86 per cent were atypical. WP's with A-V conduction ratios greater than 6:5 were all atypical. Five categories of atypical WP's are described.

Bundle of His↗
PubMed1975

Disorders of impulse conduction and impulse formation caused by hyperkalemia in man.

In eight patients we have demonstrated manifold types of impairment of impulse conduction produced by hyperkalemia. These abnormalities of impulse conduction occurred either simultaneously or in sequence, and were located in the atria, in the A-V junction, in the fascicular distribution of the ventricular conduction system, or in the free ventricular walls. In association with the abnormalities of conduction, abnormal impulse formation was also frequently observed as manifested by acceleration of normal pacemakers or the emergence of ectopic pacemakers. In one patient hyperkalemia produced alteration in sinus and A-V junctional impulse formation which overshadowed conduction disorders. In all of the eight cases the hyperkalemia was considered to be noniatrogenic. Hyperkalemia appears to potentiate subclinical conduction abnormalities, especially in the His-Purkinje system. However, the presence of pre-existent intraventricular conduction defects such as a bifascicular block does not exclude the possibility that the site of an A-V conduction delay during hyperkalemia can be in the A-V node, as demonstrated by His bundle recording in one instance after development of second-degree (type I) A-V block.

Adolescent↗