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D O'Flaherty

Publications and source records attributed to D O'Flaherty.

18 recordsLinked to original sources
PubMed1993

Esmolol.

Explore the source record for details and available documents.

Adrenergic beta-Antagonists↗
PubMed1993

Effects of surgical stimulation on autonomic reflex function: assessment by changes in heart rate variability.

Analysis of small oscillations in heart rate (known as heart rate variability or HRV) associated with the activity of homeostatic reflexes can provide a noninvasive measure of autonomic reflex function. We have investigated the effects of surgical stimulation on autonomic reflex function by assessment of changes in HRV. Healthy female patients undergoing laparoscopic tubal ligation were anaesthetized with either thiopentone-nitrous oxide-isoflurane (group I; n = 13) or continuous propofol infusion (group P; n = 13). Power spectral measurements of HRV (HRVtot = total HRV power; %HRVlo = percent of HRV power in the low frequency range) were obtained at the following times; control; before incision; after incision (3 min, 10 min and before skin closure). Compared with control values, measurements of HRVtot before incision were reduced significantly in both groups (group P: 16 (SEM 3)% of control; group I: 2.5 (0.7)% of control). With surgical stimulation, mean HRVtot in group P was restored to 55 (13)% of control (P < 0.01 compared with measurement before incision), whereas mean HRVtot in group I remained at less than 4% of control (ns). %HRVlo increased also in group P, from 49 (7)% to 75(3)% (P < 0.05), consistent with a shift in sympathetic-parasympathetic balance towards sympathetic dominance. These results suggest that surgical stimulation may have significant effects on the autonomic reflexes mediating HRV, and that such effects vary with anesthetic technique.

Adolescent↗
PubMed1993

Tracheal intubation in a mannikin: comparison of the Belscope with the Macintosh laryngoscope.

Tracheal intubation carries a risk of accidental oesophageal intubation; this is increased with inexperienced trainees, and in patients with a difficult airway. The recent introduction of an angulated laryngoscope, the Belscope, may permit a better view of the vocal cords and increase the accuracy of orotracheal intubation. To determine how easy it is to learn to use the Belscope compared with the traditional Macintosh laryngoscope, a group of medical students attempted to intubate a mannikin which had been modified to simulate a difficult intubation. Time to intubation was fast with both laryngoscopes, although faster with the Macintosh, but the Belscope produced an unexpected greater incidence of failed intubation.

Anesthesiology↗
PubMed1993

Ventilation, thermal noise, and errors in cardiac output measurements after cardiopulmonary bypass.

BACKGROUND: The authors observed transient increases in the amplitude of respiratory variations in pulmonary artery blood temperature in many patients after cardiopulmonary bypass (CPB). This increased "thermal noise" may significantly influence measurements of thermodilution cardiac outputs (TDCO) performed during this time. METHODS: The authors recorded the peak-to-peak amplitude of respiratory variations in pulmonary artery blood temperature in 15 patients during the first 35 min after CPB. Possible relationships between the amplitude of these variations and the magnitude of temperature differences between commonly monitored body temperature sites (nasopharyngeal, rectal, bladder, and pulmonary artery) were also examined. In ten additional patients, the authors investigated the influence of these increased respiratory variations on TDCO measurements by correlating the maximum variation in three successive TDCO measurements with the peak-to-peak amplitude of the respiratory variations in pulmonary artery blood temperature. Potential error in TDCO measurements caused by these increased respiratory variations in pulmonary artery blood temperature were also examined using model calculations of the effects of respiratory variations in pulmonary artery blood temperature on measured TDCO thermal areas. RESULTS: In the first 15 patients, the mean amplitude of respiratory variations in pulmonary artery blood temperature after CPB (mean +/- SEM) were: (1) within 5 min after CPB, 0.037 +/- 0.004 degrees C; (2) 10 min after #1, 0.025 +/- 0.003 degrees C; (3) 20 min after #1, 0.019 +/- 0.003 degrees C; and (4) 30 min after #1, 0.012 +/- 0.002 degrees C. There were no significant correlations between the magnitude of the respiratory variation in pulmonary artery blood temperature and the observed temperature differences between body sites. Four patients had pulmonary artery blood temperature variations in excess of the maximum amplitude previously reported in man (0.05 degrees C). In the next ten patients, the maximum variation between three successive TDCO measurements taken at specified times in the respiratory cycle (end inspiration, end exhalation, and 3 s after end exhalation) was significantly correlated with the amplitude of respiratory variations in pulmonary artery blood temperature (r = 0.83, P < 0.001). Four patients with increased respiratory variations in pulmonary artery blood temperature had variations in TDCO measurements exceeding 2 l/min. Subsequent model calculations demonstrated that the magnitude of potential error in TDCO measurements is dependent on both the amplitude of the respiratory variations in pulmonary artery blood temperature and the baseline cardiac output. On the basis of these thermal area calculations, potential errors of 15-50% could be caused by respiratory variations in pulmonary artery blood temperature > 0.05 degrees C. CONCLUSIONS: The authors concluded that respiratory variations in pulmonary artery blood temperature are transiently increased in many patients after CPB, and that this increased "thermal noise" may cause significant errors in TDCO measurements.

Body Temperature↗
PubMed1993

Inadvertent suppression of a fixed rate ventricular pacemaker using a peripheral nerve stimulator.

Electromagnetic interference usually produces only minor effects in patients with pacemakers. Nevertheless, the possibilities of serious and even fatal consequences of this complication must be recognised. This case reports an unusual anaesthetic source of interference, caused by activation of a popular nerve stimulator, resulting in cardiac arrest in a patient with a fixed-rate ventricular pacemaker.

Aged↗
PubMed1992

Tramadol: pain relief by an opioid without depression of respiration.

Two independent clinical trials were conducted simultaneously. In one, tramadol and pethidine were compared in 30 patients by patient-controlled analgesia during the first 24 h following abdominal surgery. The mean 24 h consumption of tramadol and pethidine was 642 mg and 606 mg respectively, giving a potency estimate of tramadol relative to pethidine of 0.94 (95% confidence interval 0.72-1.17). In the second trial, the effect on respiration of three doses of tramadol (0.5, 1.0, and 2.0 mg.kg-1) was compared with that of morphine sulphate (0.143 mg.kg-1) by intravenous injection during stable halothane anaesthesia. At approximately 1.5 times the equipotent dose, as estimated from the first trial, tramadol transiently depressed the rate of respiration but had no effect on end-tidal carbon dioxide tension. Morphine caused apnoea or considerable depression of ventilation. The results suggest that mechanisms other than opioid receptor activity play a significant role in the analgesia produced by tramadol.

Abdomen↗
PubMed1992

Circulatory responses during electroconvulsive therapy. The comparative effects of placebo, esmolol and nitroglycerin.

Electroconvulsive therapy is usually accompanied by activation of the autonomic nervous system, which may be harmful in patients with cerebrovascular or ischaemic heart disease. We have compared this haemodynamic response in a series of 82 electroconvulsive treatments randomly assigned to receive either nitroglycerin 3 micrograms.kg-1, esmolol 2 mg.kg-1 or placebo. These drugs were given shortly after the suxamethonium and 2 min before the electroconvulsive therapy in all cases. Heart rate was significantly lower with esmolol 1 min after therapy as was blood pressure (systolic and diastolic). The pulse rate was higher following nitroglycerin than placebo, which in turn was higher than esmolol. The three groups did not differ with regard to seizure duration. The results demonstrate that esmolol is more effective than nitroglycerin in controlling the haemodynamic response to electroconvulsive therapy. With recent emphasis on stabilisation of heart rate in preference to blood pressure in at-risk cardiac patients, our study suggests that, in the doses selected, esmolol is preferred to nitroglycerin to control the heart rate response to electroconvulsive therapy.

Adrenergic beta-Antagonists↗
PubMed1992

Endotracheal intubation skills of medical students.

The ability and confidence of clinical medical students to insert endotracheal tubes correctly and quickly and to recognize oesophageal misplacement was evaluated. Ten (33%) of the medical students intubated the trachea correctly at their first attempt but 14 (47%) incorrectly identified the position of the endotracheal tube. However, recognition improved by their second and third attempts (70% and 80% respectively). Ninety-three percent of students intubated correctly on their third attempt. Although medical students can obtain better results at correct tube placement with repeated attempts under optimum conditions--a practice effect--and do better at recognizing correct tube placement there is still a persistent failure to recognize endotracheal tube misplacement, ie oesophageal intubation. It is the ability to recognize oesophageal intubation promptly that is a life-saving skill. This essential skill should be taught during the introductory anaesthesia programme through the use of clinical patients.

Adolescent↗
PubMed1990

The end-tidal carbon dioxide detector. Assessment of a new method to distinguish oesophageal from tracheal intubation.

A new method to distinguish oesophageal from tracheal intubation using an end-tidal carbon dioxide detector was evaluated. In a prospective study on 50 healthy adult patients, the end-tidal carbon dioxide detector was reliably used to detect initial oesophageal intubation in 22 cases, and then to confirm tracheal intubation in all 50 patients. We conclude from this study that the end-tidal carbon dioxide detector is a reliable, rapid and easy method for the detection of oesophageal intubation.

Adolescent↗
PubMedDate not supplied

Total intravenous anesthesia with propofol for transsternal thymectomy in myasthenia gravis.

Patients with myasthenia gravis (MG) represent a significant management problem for the anesthesiologist. Anesthetic concerns center on the MG patient's unpredictable response to muscle relaxants and increased susceptibility to postoperative respiratory failure, resulting in prolonged dependence on mechanical ventilation. We describe the first reported use of total intravenous anesthesia with propofol to provide satisfactory surgical conditions in two patients with MG undergoing trans-sternal thymectomy. Propofol is a suitable drug for intubation and continuous infusion anesthesia, allowing fine control of anesthetic depth, good operating conditions, and a recovery profile suitable for MG patients undergoing surgery.

Adult↗