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Biomedical subjects

T H Stanley

Publications and source records attributed to T H Stanley.

At least 73 records · Page 4Linked to original sources
PubMed1987

Induction of anesthesia with fentanyl or fentanyl plus etomidate in high-risk patients.

Anesthetic doses of fentanyl (46 +/- 1.3 micrograms/kg) and oxygen (group I) were compared to a moderate dose of fentanyl (3 to 4.7 micrograms/kg; mean = 3.54 +/- 0.1 micrograms/kg) + etomidate (0.4 mg/kg) intravenously (IV) (group II) during the anesthetic induction-endotracheal intubation sequence to evaluate hemodynamic changes and the incidence of side effects in 23 New York Heart Association class III and IV patients. Chest wall rigidity only occurred in group I (27%), and pain on injection (8%) and myoclonus (25%) only in group II. Patients in group I experienced transient, small increases in central venous pressure (immediately after induction) and mean pulmonary artery pressure (after tracheal intubation). Patients in group II had small, transient decreases in heart rate, mean arterial blood pressure and cardiac index after induction which returned to baseline levels immediately after tracheal intubation. The data indicate that a modest dose of fentanyl with etomidate is similar to a large (anesthetic) dose of fentanyl in terms of avoiding cardiovascular depression and preventing hemodynamic stimulation during and following the induction-tracheal intubation sequence. Our findings also demonstrate that these doses of fentanyl before etomidate decrease but do not eliminate side effects of etomidate. The results suggest that a modest dose of fentanyl followed by etomidate may be an attractive alternative to high doses of fentanyl in patients with limited cardiovascular reserve, especially when prolonged postoperative respiratory depression secondary to high doses of an opioid is undesirable.

Adult↗
PubMed1987

Comparison of sufentanil-N2O and fentanyl-N2O in patients without cardiac disease undergoing general surgery.

Sufentanil (mean total dose 2 micrograms/kg) was compared with fentanyl (mean total dose 15 micrograms/kg) as a supplement to 60% N2O anesthesia in 30 adult patients undergoing general surgical procedures. Comparisons were made with respect to stability of hemodynamic variables (heart rate and systolic and diastolic blood pressure), changes in stress hormones (cortisol, antidiuretic hormone, epinephrine, norepinephrine, and dopamine), recovery of alertness and orientation, time to extubation, postoperative analgesia, and measures of respiratory depression (resting end-tidal carbon dioxide tension [PETCO2], CO2 response curve for minute ventilation [delta VE/delta PETCO2]). Hemodynamic variables remained stable and similar in both groups throughout the study. Plasma hormone levels remained similar to baseline in both groups until 1 h postoperatively when epinephrine levels were significantly elevated in both groups (P less than 0.05). Recovery times, including time to extubation, were similar in both groups. Patients given sufentanil had less pain 30 min postoperatively than those given fentanyl, although at 60 min postoperatively pain levels were similar in both groups. Small but significant elevations in resting PETCO2 were seen in both groups postoperatively (P less than 0.05), but postoperative delta VE/delta PETCO2 responses were significantly depressed only in patients receiving fentanyl (P less than 0.05). The results of this study demonstrate that sufentanil-N2O anesthesia is as effective as fentanyl-N2O in attenuating the hemodynamic and hormonal responses to the stress of general surgery. Because continuous intraoperative PETCO2 monitoring was not employed in this study, intraoperative hypocapnea cannot be strictly excluded as a possible influence on the postoperative measures of ventilatory drive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Opiate anaesthesia.

Current use of opioids in anaesthesia is reviewed with particular emphasis on the use of opioids in anaesthetic doses, techniques that recently have become popular in cardiovascular anaesthesia. A major benefit of opioid anaesthesia (particularly fentanyl) is the cardiovascular stability which obtains during induction and throughout operation, even in patients with severely impaired cardiac function. Anaesthetic doses of morphine are associated with a higher incidence of cardiovascular disturbances and other problems. Pethidine is unsuitable for cardiovascular surgery because of severe haemodynamic disturbances when high doses are given. Sufentanil and alfentanil may prove more suitable alternatives. High doses of opioids can reduce or prevent hormonal and metabolic responses to the stress of surgery. Even very large doses of fentanyl or its new analogues do not prevent marked increases in plasma catecholamine concentrations in response to cardiopulmonary bypass. The reduction in hormonal and metabolic stress response does not appear to continue postoperatively.

Analgesics, Opioid↗
PubMed1987

Removal of tracheal secretions in anesthetized dogs: balloon catheters versus suction.

Artificial secretions were removed by suction (using 12- or 18-French suction catheters) or by means of a balloon-tipped catheter (6-French Fogarty arterial embolectomy catheter) in 20 experiments performed on five dogs anesthetized with halothane. Each dog had 5 ml of mucin injected 10 cm down the endotracheal tube prior to a 30-sec period of intermittent positive pressure ventilation. After this procedure, the ventilator was disconnected and the secretions were removed by suction with the 12- or 18-French catheters or by the Fogarty catheter. Each dog had balloon removal performed twice and suction performed once with the 12-French and once with the 18-French catheter. The endotracheal tube was cleaned and a 15-min stabilization period was allowed between each experiment. Arterial blood pressure (MAP) and pulmonary artery pressure (PAP) did not change after either technique. There were no ECG changes, arrhythmias, or alterations in PaCO2. The PaO2 was significantly lower in the two suction catheter groups [520 +/- 33 mm Hg (12 French) and 451 +/- 31 mm Hg (18 French)] than in the balloon removal group (564 +/- 10 mm Hg) (P less than 0.05). The balloon technique removed more secretions (4.52 +/- 0.06 ml) than did suction (12 French, 1.32 +/- 0.17 ml; 18 French, 2.11 +/- 0.44 ml). Balloon removal of tracheal secretions has two advantages over conventional suction techniques: it removes more secretions, and it has less detrimental effect on arterial oxygenation.

Anesthesia, Endotracheal↗
PubMed1987

Is fentanyl an anesthetic in the dog?

The authors used the absence of vocalization and movement during application of a hemostat clamped to the first ratchet at the base of the tail as an indication of anesthesia for evaluation of the anesthetic properties of fentanyl in the dog. Eighty-six unpremedicated, unrestrained, untrained mongrel dogs were given one of eight doses of fentanyl citrate (125, 250, 500, 750, 1000, 1500, 2000, and 3000 micrograms/kg) as a single intravenous bolus injection. Dogs breathed spontaneously without oxygen supplementation. Anesthesia was assessed every 5 min until absence of anesthesia was recorded for two consecutive evaluations. Venous plasma samples were obtained in two or three dogs receiving each of the doses of fentanyl 5 min after fentanyl injection and again when application of the tail clamp elicited either vocalization or movement (positive response). Fentanyl resulted in recumbency in all animals except two receiving 125 micrograms/kg. Although all doses of fentanyl produced anesthesia in at least one animal 5 min after injection, the duration of anesthesia was short, responses unpredictable, and anesthesia achieved in all animals only with a dose of 3000 micrograms/kg. Increasing doses of fentanyl resulted in higher plasma fentanyl concentrations 5 min after injection and at the time of the first positive response to tail clamp but there was great variability. All doses of fentanyl caused statistically significant decreases in heart and respiratory rates but none produced apnea or a PaCO2 higher than 67 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗
PubMed1987

Antagonism of postoperative opioid-induced respiratory depression: nalbuphine versus naloxone.

The authors compared naloxone and nalbuphine as antagonists of opioid-induced respiratory depression to determine the relative efficacies and safety of the two agents. In a double-blind, randomized fashion, 90 anesthetized patients received a mean dose of 25 micrograms/kg fentanyl during surgery. Inadequate spontaneous respirations at the end of anesthesia were treated with either naloxone 0.08 mg or nalbuphine 2.5 mg IV every 2 min while heart rate (HR), systolic and diastolic blood pressures (SBP, DBP), respiratory rate (RR), and tidal volume (TV) were measured at 2-min intervals. Arterial blood samples for analysis of PaCO2, PaO2, and pH were drawn when spontaneous ventilation resumed, and 30 and 60 min later. Narcotic antagonism and respiration were deemed adequate when TV was greater than or equal to 4 ml/kg and RR greater than or equal to 8 breaths/min. Heart rate, SBP, DBP, TV and RR were recorded, as were the occurrence of renarcotization (RR less than 8) and analgesic requirements every 5 min during the recovery room stay. Sixty of 90 patients required narcotic antagonism at the end of surgery. No patient required more than three doses (0.24 mg) of naloxone or four doses (10 mg) of nalbuphine. Both antagonists produced similar and moderate increases in SBP and HR while restoring adequate spontaneous ventilation. There were no significant differences in TV, RR, or arterial blood gases (ABGS) between the two groups after narcotic reversal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Anesthesiology in the 21st century: analgesic, sedative and anesthetic focusing.

The specialty of anesthesiology is on the verge of a major technological evolution (revolution) which will utilize the computative and logic powers of the computer as well as the recent and rapid advances in magnetic imaging and laser and drug receptor technology to introduce the concept of anesthetic drug focusing by the beginning of the next century. This will result in the need for only a few molecules of future anesthetic compounds because they will only be necessary at a limited number of receptors in a few neurons or nuclei in the brain and/or spinal cord. Analgesic, sedative and anesthetic action may not be dependent on any drug but rather be produced solely by a wave form or energy source focused via a computer on the appropriate receptors in the brain, spinal cord or peripheral nerves. Anesthetic drug focusing will enable anesthetic depth to be ideal, anesthetic action to be localized to only those cells, tissues or organs where it is desired and anesthetic onset and termination to be measured in micro-seconds.

Analgesics↗
PubMed1986

Duchenne muscular dystrophy and malignant hyperthermia--two case reports.

The case histories are presented including the anaesthetic and postoperative management, of two children, a two-year-old with undiagnosed Duchenne muscular dystrophy (DMD) and a three-year-old with known DMD. The child with undiagnosed DMD had no symptoms of DMD and had received halothane twice before, without succinylcholine, with no apparent difficulty. Following an uneventful induction of anaesthesia with halothane, nitrous oxide and O2, succinylcholine resulted in bilateral masseter muscle spasm and then, in rapid sequence, ventricular tachycardia and cardiac arrest. Resuscitation was difficult, prolonged and associated with hyperkalaemia (K+ = 12.57 mEq X L-1), severe metabolic and respiratory acidosis, high peripheral venous pressure and massive hepatosplenomegaly, but not hyperthermia. The patient was finally resuscitated but died two days later. Skeletal muscle biopsy results were consistent with malignant hyperthermia. The second patient was known to have DMD but did not receive prophylactic or intraoperative dantrolene nor have his anaesthetic machine flushed with oxygen for an extended period prior to induction of anaesthesia. This child was anaesthetized with fentanyl and N2O and, with the exception of a high intraoperative heart rate (155-160 beats X min-1), had an uncomplicated anaesthetic and operation (intraoperative axillary temperatures ranged between 36.8-37.9 degrees C). Postoperatively his temperature rapidly increased to 38.8 degrees C and then 40.3 degrees C and he became metabolically acidotic. Intravenous administration of dantrolene for 48 hours reduced the temperature and allowed normal recovery and discharge. A postoperative muscle biopsy was consistent with DMD.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1986

Variability of the respiratory response to diazepam.

The authors investigated the respiratory effects of diazepam in 24 healthy volunteers using a modified Read rebreathing circuit. Resting end-tidal CO2 (PETCO2) and the slopes of the ventilatory (VE/PETCO2) and occlusion pressure (P0.1/PETCO2) response to CO2 were measured just prior to and 5, 20, 40, and 60 min after diazepam, 0.1 mg/kg iv. The slope of VE/PETCO2 for all 24 subjects analyzed as a single group was never significantly depressed. The slope of P0.1/PETCO2 for all 24 subjects analyzed as a single group was significantly depressed only at 5 min after diazepam. The resting PETCO2, however, had small but statistically significant increases throughout the 1 h of study. Group or cluster analysis of the slope of P0.1/PETCO2 clearly divided subjects into one group of five subjects, whose P0.1/PETCO2 slope was significantly and consistently augmented for 1 h and a second group of 19 subjects whose P0.1/PETCO2 slope was always less than control for the entire hour. Diazepam may, through effects on pulmonary mechanics and/or the central nervous system, sometimes enhance respiratory responses to CO2 rebreathing. Failure to select for such group effects when studying drug effects by CO2 rebreathing may obscure the severity and duration of respiratory depression that occurs in the majority of individuals. Resting PETCO2 indicated consistent depression of resting minute ventilation by diazepam and may be a more appropriate or sensitive measure of mild or subtle drug-induced respiratory effects.

Adult↗
PubMed1986

Failure of nalbuphine to antagonize morphine: a double-blind comparison with naloxone.

The authors studied the respiratory and analgesic effects of nalbuphine (0.21 mg/kg, intravenous), naloxone (0.014 mg/kg, intravenous), and placebo (normal saline) when given after morphine (0.21 mg/kg, intravenous) in a double-blind, randomized fashion. Resting end-tidal CO2 (PETCO2), ventilatory and occlusion pressure responses to CO2 rebreathing, and pain threshold were measured in 12 healthy adult volunteers before, 5 min, and 30 min after morphine. Nalbuphine, naloxone, or saline were administered 55 min after morphine, and the above measurements were repeated 5 min later (60 min after morphine) as well as 90, 120, 180, and 240 min after morphine. Whereas naloxone reversed respiratory depression as measured by all three respiratory parameters, nalbuphine either further depressed (resting PETCO2) or did not affect (ventilatory and occlusion pressure responses to CO2 rebreathing) respiratory drive. Morphine produced a significant elevation of the pain threshold. Significant decreases in the pain threshold were seen only after naloxone. Saline and nalbuphine did not significantly alter the pain threshold. The data indicate that nalbuphine may not reliably antagonize moderate doses of morphine.

Adult↗
PubMed1985

Transcutaneous PO2 poorly estimates arterial PO2 in adults during anesthesia.

We compared values of PaO2 and transcutaneous PO2 in 21 adult patients during anesthesia. In 282 simultaneous determinations during anesthetic periods of 3-10 h, transcutaneous PO2 was a poor predictor of absolute PaO2 and changes in PaO2. Transcutaneous PO2 monitoring in adults during anesthesia is of unproven value.

Adult↗
PubMed1985

Placement of the pulmonary arterial catheter before anesthesia for cardiac surgery: a stressful, painful, unnecessary crutch.

Catheterization of the pulmonary artery (PA) in patients with cardiac or major vascular disease is a popular practice. However, controversy surrounds the question of whether the PA catheter should be inserted before or after the induction of anesthesia. Review of the literature supports insertion after induction for several reasons. First, the information provided by a PA catheter may be misleading, since it does not provide a direct measurement of left ventricular function, but rather, an indirect reflection that is subject to many variables. Second, pharmacologic intervention before anesthesia to correct hemodynamic abnormalities detected by a PA catheter has not been shown to improve induction of anesthesia or outcome after cardiac surgery. Induction of anesthesia with synthetic narcotics in patients with either normal or abnormal hemodynamic function is fast and uneventful, making insertion of a PA catheter before induction unnecessary. Finally, the act of inserting a PA catheter produces cardiovascular stimulation that can lead to myocardial ischemia. Thus, insertion of a PA catheter can be more safely and rationally performed after the induction of anesthesia.

Anesthesia↗
PubMed1985

Anesthetic induction with fentanyl.

The efficacy of fentanyl, 30 micrograms/kg, was evaluated as an anesthetic induction agent in 72 ASA I-III patients scheduled for 2-4-hr operations. The effect of preinduction pretreatment with pancuronium and/or diazepam and the incidence of loss of consciousness (anesthesia), recall, rigidity, abnormal muscle movements, and hemodynamic changes were documented. Seventy-four percent of all patients became anesthetized. Diazepam pretreatment enhanced but did not ensure success of anesthetic induction. There was a significant correlation between age and the incidence of unconsciousness (P = 0.0287) and all patients over 60 yr old were anesthetized with 30 micrograms/kg of fentanyl. The incidence and severity of rigidity was reduced by pancuronium (P = 0.0002) but not by diazepam pretreatment. However, pancuronium plus diazepam produced a significant reduction in the incidence of rigidity when compared to pancuronium alone (P = 0.031). A significant positive correlation between age and the incidence of rigidity (P = 0.003) was found. Six patients had focal and one patient global tonic-clonic abnormal muscle movements. Diazepam but not pancuronium significantly decreased both heart rate (P = 0.05) and blood pressure (P = 0.04). Seventeen patients required reversal of narcotic effect to restore adequate spontaneous respiration after surgery. No patient required postoperative mechanical ventilatory assistance. The results of this study demonstrate that 30 micrograms/kg of fentanyl is not a reliable anesthetic induction dose in patients less than 60 yr old. Both age and premedication enhance the anesthetic capabilities of induction with fentanyl.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗