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Biomedical subjects

F L Roberts

Publications and source records attributed to F L Roberts.

18 recordsLinked to original sources
PubMed2005

An investigation into the reduction in flow rate of intravenous fluid by antireflux valves.

We have investigated the extent to which antireflux (non-return) valves impede the maximum flow rate of crystalloid in intravenous infusion systems when administered either under gravity or with 300 mmHg added pressure. When used with a 16G cannula, a reduction in flow rate of 19-38% was consistently seen. With a 20G cannula, no significant reduction in flow was found. The valve tested that produced the least reduction in flow was the Westcott Sae-flo valve.

Catheterization, Peripheral↗
PubMed2001

Airway obstruction with cricoid pressure and lateral tilt.

We studied the effect of cricoid pressure and lateral tilt on airway patency during ventilation by facemask in a simulated obstetric setting. The lungs of 50 patients were ventilated by facemask and Guedel airway using a Nuffield Penlon 200 ventilator and Bain system with standard settings. Expired tidal volumes and peak inspiratory pressures were recorded for 10 breaths in each of four combinations: supine with no cricoid pressure, supine with cricoid pressure, 15 degrees lateral tilt with no cricoid pressure and 15 degrees lateral tilt with cricoid pressure. The timing of cricoid pressure was randomised and blinded to all observers. In both supine and tilted positions, cricoid pressure produced a reduction in tidal volume (p < 0.001) and an increase in peak inspiratory pressure (p < 0.001). Cricoid pressure with lateral tilt did not produce any additional airway obstruction to that in the supine position. Complete airway obstruction (tidal volume < 200 ml) resulted on three occasions, all with cricoid pressure applied.

Adolescent↗
PubMed1992

Epidural infusion of bupivacaine and diamorphine for postoperative analgesia. Use on general surgical wards.

An audit of postoperative epidural analgesia in a District General Hospital is presented. Three hundred and forty-eight patients received epidural infusions of a bupivacaine and diamorphine mixture, and were managed on general surgical wards using a standard protocol of observations and instructions. Good analgesia was achieved in 339 (97%) patients. Respiratory depression, defined as a respiratory rate of eight breaths.min-1 or less, occurred in 22 (6%) patients, was of gradual onset, and was simply and successfully managed without morbidity. There were no respiratory arrests. Other complications, and the significance of catheter insertion level are discussed.

Adolescent↗
PubMed1992

Carbon dioxide pneumothorax occurring during laparoscopic cholecystectomy.

A previously fit patient underwent laparoscopic cholecystectomy. During the procedure arterial oxygen saturation fell and clinical examination revealed signs of a right pneumothorax confirmed by chest X ray. Aspiration of the pleural cavity and analysis of the gas removed showed it to be composed entirely of carbon dioxide. Possible mechanisms of entry of carbon dioxide into the pleural space are discussed.

Carbon Dioxide↗
PubMed1990

Study of the possible interaction between fentanyl and propofol using a computer-controlled infusion of propofol.

A computer-controlled infusion of propofol designed to achieve a target blood concentration of propofol 3 microgram ml-1 was used to investigate the possibility of an interaction between propofol and fentanyl in 32 patients undergoing body surface surgery. In 16 patients who were not receiving a neuromuscular blocker during maintenance anaesthesia with 67% nitrous oxide, there were no significant differences in blood concentrations of propofol between eight patients who received fentanyl 5 micrograms kg-1 before induction of anaesthesia, and eight patients who did not. In a further 16 patients who received vecuronium during maintenance anaesthesia with 67% nitrous oxide, there were no significant differences in blood propofol concentrations between eight patients who received fentanyl 5 micrograms kg-1 before induction of anaesthesia, and eight patients who did not. Fentanyl administered i.v. immediately before a computer-controlled infusion of propofol resulted in more satisfactory anaesthetic conditions than when fentanyl was not used, but did not significantly prolong the recovery time.

Adult↗
PubMed1989

Comparison of hyperbaric and plain bupivacaine with hyperbaric cinchocaine as spinal anaesthetic agents.

In a double-blind study, 90 patients (ASA 1 or 2) received spinal anaesthesia with 2 ml hyperbaric cinchocaine 0.5%, 4 ml hyperbaric bupivacaine 0.5% or 4 ml plain bupivacaine 0.5%. All injections were made in the left lateral position, and the patients turned supine immediately. Hyperbaric bupivacaine produced a significantly faster and a higher dermatomal level of bilateral complete sensory blockade than the other solutions (p less than 0.005 for each). The duration of sensory blockade was significantly longer with plain bupivacaine than with either hyperbaric solution (p less than 0.0005). The intensity of sensory blockade was significantly greater with both bupivacaine solutions than with hyperbaric cinchocaine (p less than 0.05). Onset and intensity of motor blockade were similar with all agents, but motor blockade was of significantly shorter duration with hyperbaric bupivacaine than the other agents (p less than 0.0005). Hyperbaric bupivacaine appears to be the best agent for rapid and intense sensory blockade of intermediate duration. Plain bupivacaine is more appropriate if a longer duration of action but a lower height of blockade are required, and has the advantage of less cardiovascular disturbance.

Aged↗
PubMed1988

Induction and maintenance of propofol anaesthesia. A manual infusion scheme.

A simple, manually controlled infusion scheme for continuous administration of propofol was derived by simulation of a computer algorithm designed to achieve a predetermined blood concentration of propofol within 2 minutes and to maintain a constant blood level for the duration of surgery. The manual infusion scheme for a target blood propofol concentration of 3 micrograms/ml, consisted of a loading dose of 1 mg/kg followed immediately by an infusion of 10 mg/kg/hour for 10 minutes, 8 mg/kg/hour for the next 10 minutes and 6 mg/kg/hour thereafter. An overall mean blood propofol concentration of 3.67 micrograms/ml was achieved within 2 minutes and maintained stable for the subsequent 80-90 minutes of surgery. The decrease of systolic and diastolic arterial pressures at induction was much less than that previously described after larger induction doses of propofol and there was a negligible haemodynamic response to laryngoscopy and intubation or to the subsequent surgery. The quality of induction and maintenance of anaesthesia was satisfactory in every patient.

Adult↗
PubMed1986

Thiopental and epinephrine-induced dysrhythmias in dogs anesthetized with enflurane or isoflurane.

Epinephrine-induced dysrhythmias were studied in 19 dogs anesthetized with 1.25 MAC enflurane or isoflurane, or the same preceded by thiopental (20 mg/kg). In 11 (group 1) dogs, thiopental reduced the dose of epinephrine required for production of ventricular ectopy, bigeminy and tachycardia with enflurane, and only ventricular tachycardia with isoflurane (P less than 0.05). Thiopental potentiation of epinephrine-induced dysrhythmias with enflurane lasted 4 hr after induction. In eight (group 2) dogs, the arrhythmic dose (ADE in microgram/ml) and plasma level of epinephrine (PLE in ng/ml) for four or more ventricular extrasystoles in 15 sec were determined in the same animal under each of the four test conditions. ADE and PLE values (X +/- SEM) were, respectively, enflurane, 9.1 +/- 1.0 and 141 +/- 24 (8/8 dogs); enflurane-thiopental, 5.0 +/- 0.6 and 63 +/- 16 (8/8 dogs); isoflurane, 28.3 and 330 (1/7 dogs); and isoflurane-thiopental, 15.2 +/- 2.8 and 265 +/- 59 (5/7 dogs). In addition, thiopental had no effect on plasma epinephrine levels reached during epinephrine infusions with 1.0 (enflurane only), 2.0 (enflurane, isoflurane) and 4.0 micrograms X kg-1 X min-1 (isoflurane only). Nor were epinephrine levels reached during enflurane or enflurane-thiopental different from those reached during isoflurane or isoflurane-thiopental. It is concluded that thiopental potentiates several types of epinephrine-induced ventricular dysrhythmias with enflurane, but only ventricular tachycardia with isoflurane. Furthermore, isoflurane or isoflurane-thiopental were less sensitizing than enflurane or enflurane-thiopental. Finally, neither thiopental nor the anesthetic agents affected plasma epinephrine levels reached during epinephrine infusions lasting 3 min.

Animals↗