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Biomedical subjects

R M Jones

Publications and source records attributed to R M Jones.

At least 235 records · Page 13Linked to original sources
PubMed1984

Atracurium for short surgical procedures in day patients.

Atracurium was studied in day-stay patients undergoing short surgical procedures requiring tracheal intubation. In a dose of 0.25 mg kg-1 and with an anaesthetic technique using enflurane, tracheal intubation could be performed in all patients within 3 min and was readily reversible, unless the duration of surgery was less than 20 min. The administration of an antagonist was indicated in nearly all patients in whom surgery lasted for less than 30 min.

Adult↗
PubMed1984

Smoking and anesthesia: preoperative abstinence and perioperative morbidity.

Much less is known of the effects of stopping smoking than of continuing to smoke, and many of the studies on smoking cessation are concerned with long-term effects rather than effects within 48 hr. Studies concerned with this period are required, especially in terms of postoperative respiratory morbidity, before an authoritative assessment can be made of the benefits and risks of stopping smoking in the short period before operation. Present studies are convincing that great benefit will accrue in the cardiovascular system, mainly from carbon monoxide and nicotine elimination, after 12-24 h. A few days may greatly improve ciliary beating and 1-2 weeks provide a significant reduction in sputum volume. However, a minimum period of 4-6 weeks would seem appropriate to greatly influence postoperative respiratory morbidity, although the statement that "one needs 4-6 weeks to influence postoperative respiratory morbidity" must not be misapplied and become "there is no point in giving up smoking unless it is 4-6 weeks prior to operation." There are no proven disadvantages to the respiratory system from stopping smoking in the short term, and it seems unwise to sacrifice proven advantages for a theoretic consideration that sputum may become "stickier" and more difficult to clear. Less is known with regard to the time course of offset of smoking effects on drug metabolism and the immune system, although 6-8 weeks would be expected to produce some benefit.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesics↗
PubMed1984

Nifedipine and cardiopulmonary bypass. Post-bypass management after continuation or withdrawal of therapy.

The management of the period after hypothermic cardiopulmonary bypass has been compared in a group of patients maintained on nifedipine therapy, a group who had the drug withdrawn at least 24 hours prior to cardiac surgery, and a control group who had never received calcium antagonists. Patients in the drug withdrawal group were significantly more likely to need vasodilator intervention than the treated (p less than 0.001) or the control (p less than 0.05) groups. Although nifedipine withdrawal appeared to reduce the need for inotropic support, compared to treated (p less than 0.001) and control groups (p less than 0.005), this may be at the cost of increasing systemic vascular resistance. This observation, coupled with reports of a rebound phenomenon following abrupt withdrawal of calcium antagonist therapy, suggests that nifedipine should be continued up to the time of surgery.

Adult↗
PubMed1984

Anaesthetic considerations in patients with paroxysmal supraventricular tachycardia. A review and report of cases.

Paroxysmal supraventricular tachycardia is a common cardiac dysrhythmia which may or may not be associated with heart disease. The underlying mechanisms in the genesis of this dysrhythmia are alterations in automaticity or re-entry of the cardiac impulse. These mechanisms are reviewed in the context of the stresses of the peri-operative and operative periods. The anaesthetic management of three patients, particularly prone to paroxysmal supraventricular tachycardia, is described based on principles derived from the pathophysiology of re-entrant or ectopic atrial tachydysrhythmias.

Adult↗
PubMed1984

Sleep apnoea following cervical cord surgery.

Two patients who developed sleep apnoea following upper cervical cord surgery are described. The underlying mechanisms and management of the sleep apnoea syndrome are discussed.

Adolescent↗
PubMed1984

Anaesthetic considerations in the mucopolysaccharidoses.

The anaesthetic problems we have encountered in eight patients with the mucopolysaccharidoses are described and the pathophysiology of this group of clinically progressive inherited diseases is reviewed with emphasis on the aspects of importance to the anaesthetist.

Adolescent↗
PubMed1984

Naproxen pharmacokinetics in the elderly.

While naproxen pharmacokinetics appear to be altered in the presence of both diminished renal and hepatic function, the degree to which naproxen disposition might be influenced in the elderly by concurrent alteration in these functions is not obvious. Total plasma clearance/bioavailability (CL/F) of naproxen after a single 375 mg oral dose was found to be less in a group of 10 healthy men between 66 and 81 years of age than in 10 healthy men between 22 and 39 years (0.318 +/- 0.078, 0.416 +/- 0.061 l/h). At steady state (375 mg, 12 hourly), however, CL/F was statistically indistinguishable between the two groups. The fraction of naproxen unbound to plasma protein was doubled in elderly subjects, both at peak and trough drug concentrations. The lowered protein binding tended to obscure a 50% decrement in the intrinsic clearance of naproxen in the elderly as estimated by unbound clearance/bioavailability (213 +/- 64, 396 +/- 155 l/h). As a result, mean steady-state plasma concentrations of naproxen were indistinguishable between the elderly and young (64.2 +/- 8.5, 58.2 +/- 8.1 mg/l) but the elderly generated twice the mean steady-state unbound plasma drug concentration (0.157 +/- 0.039, 0.0859 +/- 0.0212 mg/l). Since it is the unbound drug concentration which appears in general to relate more closely to pharmacological and toxic effect, it may be advisable to reduce naproxen doses by half in the elderly, pending plasma drug concentration-response studies in this age group. If a similar perturbation with age occurs in benoxaprofen protein binding as was observed with naproxen, benoxaprofen intrinsic clearance in the elderly might be only one quarter of that in younger individuals; a factor which may contribute to the toxicity of this drug in the elderly.

Adult↗
PubMed1984

Late response in exercise-induced asthma.

Eight subjects induced bronchospasm by free-range running. Four of these demonstrated a late response at 5-6 hr after exercise. When compared to the other group of four subjects, who also developed an early response but no late response, the difference in FEV1 at 5-6 hr was highly statistically significant. Although the phenomenon is not universally manifest it should no longer be held that there is no late response in exercise-induced asthma.

Adolescent↗
PubMed1984

Lorazepam in open-heart surgery--plasma concentrations before, during and after bypass following different dose regimens.

Thirty-six patients (29 males and 7 females) undergoing open-heart surgery received one of three different dose regimens of lorazepam. All received a weight-related oral dose (2 mg, 3 mg or 4 mg) pre-operatively for night sedation. Twenty-four patients had an additional weight-related dose (2 mg, 3 mg or 4 mg intravenously) either as part of the induction (12 patients) or just prior to connection of the heat-lung machine (12 patients). Plasma concentrations of lorazepam were measured 20 minutes after induction, immediately before bypass, 30 and 60 on bypass and 30 minutes after bypass. Only when additional intravenous lorazepam was given prior to connection to the heart-lung machine were plasma lorazepam concentrations obtained compatible with complete amnesia.

Adult↗
PubMed1984

The anaesthetic management of the Eisenmenger syndrome.

The Eisenmenger syndrome is a form of cyanotic congenital heart disease not usually amenable to corrective surgery. It is, however, compatible with leading an active life in early adulthood and due to advances in medical therapy it is not uncommon for patients with this syndrome to live to 30 years or more. Occasionally, therefore, anaesthetists and surgeons will be required to care for these patients when they present for incidental surgery. This article reviews the appropriate measures for the safe operative and perioperative care of patients, based on an understanding of the pathophysiological changes which occur in the Eisenmenger syndrome.

Anesthesia, Conduction↗
PubMed1984

Clinical comparison of inhalation anaesthetic agents.

Despite the continued revival in the use of local anaesthetic techniques, and the fact that some of the versatility of inhalation agents is being approached by newer short acting i.v. anaesthetic and analgesic agents, volatile anaesthetics will continue to play an important role in the management of patients undergoing surgery. The individual agents have distinct properties and varying benefit-to-risk ratios depending upon the medical status of the patients and the type of surgery to be undertaken. In certain circumstances, such as their role in the anaesthetic management of patients with coronary artery disease, it is possible--even probable--that in some situations the characteristics of one agent will be particularly advantageous, whereas the characteristics of another agent will be more appropriate in another situation. Further investigations directly comparing the three agents in particular clinical situations need to be undertaken before any clear picture will begin to emerge. In other circumstances there is already sufficient evidence to suggest that one of the agents is superior to the other. The stability of cardiac rhythm which accompanies isoflurane anaesthesia is an example of this, and the smoother inhalation induction of anaesthesia obtained with halothane is another. Perhaps the greatest advantage of isoflurane compared with halothane and, to a lesser extent, enflurane is the remarkable molecular stability of the molecule. This stability has implications with regard to the probable lack of toxicity of this agent--both organ toxicity and the effects of long term exposure in operating theatre personnel. Although the agent will need to be in general use for a longer period of time before any definite judgments can be made in this respect, the laws of pharmacology generally dictate that such a prediction will probably be fulfilled. Although this review has been a clinical comparison of halothane, enflurane and isoflurane, the relative cost of these agents must be mentioned. Isoflurane is much more expensive than halothane, and again (as so often seems to be the case when comparing the relative merits or properties of these agents) enflurane is intermediate between the two.

Anesthesia, Inhalation↗
PubMed1983

Therapeutic and prophylactic efficacy of morantel when administered directly into the rumen of cattle on a continuous basis.

The efficacy of morantel tartrate when administered on a continuous basis directly into the rumen/reticulum of cattle, either by a cannula or from a specially designed device, was evaluated against gastrointestinal parasites under laboratory conditions. In two experiments the continuous infusion of morantel at rates between 0.26 and 1.04 mg/kg body weight per day using a peristaltic pump was highly efficacious in both preventing the establishment of infections and removing established infections of the following species: Ostertagia ostertagi, Haemonchus contortus, Cooperia oncophora and Trichostrongylus colubriformis. The same dose rates also prevented establishment of Dictyocaulus viviparus infection but were ineffective against established infections of this parasite. In another two experiments the continuous release of morantel tartrate for at least 60 days (at rates between 0.65 and 1.11 mg/kg body weight per day) from a specially designed intraruminal sustained release bolus (secured at each end by a polyethylene impregnated semi-permeable membrane) was highly efficacious in both preventing the establishment of infections and removing established infections of the following species: O. ostertagi, T. axei, T. colubriformis and C. oncophora.

Animals↗
PubMed1983

Morantel sustained release bolus: a new approach for the control of trichostrongylosis in Austrian cattle.

The efficacy of a morantel sustained release bolus to control gastrointestinal parasitism during two consecutive grazing seasons was assessed in replacement dairy heifers raised under field conditions in Austria. Thirty calves were randomly allotted into two equal groups and maintained throughout the 1979 summer pasturing season on adjacent pastures of equal size with identical grazing history. Twenty-four of the thirty calves used in 1979 were monitored throughout 1980, each animal remained in the same treatment group as the previous year and grazed the same pastures as the previous year. In both 1979 and 1980 the bolus was administered to each animal in the treated group one week before turnout onto spring pastures, while the control animals received no anthelmintic treatment during either year. The efficacy of the bolus was assessed by comparison of faecal worm egg counts, herbage larval counts, worm counts from tracer and principal trial animals, weight gains and by the incidence of clinical disease found in both tracer and trial animals throughout the grazing season. Milk production was also monitored for all animals in both treatment groups during the first lactation. The system of treatment used in the present study with the morantel sustained release bolus was highly effective in preventing a significant buildup of infective larvae on pasture to the end of the grazing season in both years. In 1979 worm counts of tracer calves grazed on the treated pastures in mid-August were similar to those recorded at the beginning of the season, while worm counts in the control tracers were five times the total found at the beginning of the season. In 1979 the bolus-treated calves outperformed the control group by 34.8 kg (P less than 0.001) over the 168-day grazing period. These results demonstrated that administration of the bolus to calves at the time of turnout onto spring pastures was most effective both in controlling parasites within the cattle themselves and in reducing the level of parasite contamination. During the second grazing season (1980) no beneficial effect in weight gain was observed due to the second bolus treatment. Weight gains realized during the first year, however, largely remained through the second year and the bolus-treated heifers reached breeding weight on average 19 days earlier. No difference in milk yield was observed between the treated and control animals during thier first year of lactation.

Animals↗