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G D Stanley

Publications and source records attributed to G D Stanley.

12 recordsLinked to original sources
PubMed1999

Pharmacology.

When performing IVCS, one must never forget the primary goal of providing patient comfort without compromising cardiopulmonary function or the patient's ability to react purposely to verbal commands and physical stimuli. When it is anticipated that required sedation will lead to loss of protective airway reflexes, such patients require a greater level of care than exists with IVCS. Deep sedation is a complication of IVCS and must be avoided. In deep sedation, one creates a state of depressed consciousness from which the patient is not easily aroused, accompanied by a partial or complete loss of protective reflexes, including the ability to maintain a patent airway independently and respond purposely to physical stimuli or verbal commands. In keeping this goal in mind, understanding those situations in which patients are at increased risk should be emphasized. In general, the elderly show increased sensitivity to the drugs used for IVCS, so the dose and frequency of administration should be reduced. In addition, patients with COPD appear to be more sensitive to the respiratory depressant effects of narcotics and benzodiazepines, especially when used in combination. Patients with low serum albumin concentrations show increased sensitivity to drugs that are highly protein bound such as thiopental because more free drug is available for therapeutic effect. To avoid hypotention, caution should be exercised in patients with poor left ventricular function or borderline volume status before the administration of IVCS. Understanding the metabolism and excretion of the agents used for IVCS is critical to avoid oversedation. Drugs such as diazepam, morphine, meperidine, and fentanyl have active metabolites, so the potential for drug accumulation and prolonged effect certainly exists. Patients with renal disease are particularly susceptible to CNS toxicity from normeperidine because of the accumulation of the active metabolite. Drugs like fentanyl, although short acting, have prolonged activity as a result of seepage of stored drug back into the systemic circulation. In contrast, thiopental is metabolized to water-soluble inactive metabolites. Careful titration to effect with dosage adjustments will avoid unnecessary oversedation with resultant respiratory and cardiovascular complications. Time should elapse between repeat doses to allow peak effects to occur. In addition, potential drug interactions that can prolong the effects should be recognized. Examples of the latter are the interaction between cimetidine and diazepam or the protease inhibitors and the benzodiazepines, in which the potential exists for excessive and prolonged sedation. The use of the narcotic antagonist naloxone and the benzodiazepine antagonist flumazenil should be scrutinized because they should be reserved for the unusual situation in which excessive cardiopulmonary depression occurs. Maintenance of a patent airway and stable cardiovascular function in a patient who can respond to verbal commands and physical stimuli is the primary goal of IVCS. With the agents discussed in this chapter, this goal is easily obtained, keeping the principles just mentioned in mind with all the appropriate monitoring guidelines discussed elsewhere in this text.

Age Factors↗
PubMed1999

Complications in IVCS and management.

Choose your patients carefully. Check and understand your equipment. Be vigilant and prepared for the unexpected event. Remember basic airway techniques. Have differential diagnoses for the more common complications. Have clearly defined personal and departmental plans to deal with emergency situations. Use medication judiciously; you cannot take it out but you can always give more! The use of reversal agents should never be routine.

Airway Obstruction↗
PubMed1997

Anesthesia type does not influence early graft patency or limb salvage rates of lower extremity arterial bypass.

PURPOSE: The effect of anesthesia type on 30-day graft patency and limb salvage rates was evaluated in patients who underwent femoral to distal artery bypass. METHODS: Of 423 patients randomly assigned to receive general, spinal, or epidural anesthetic, 76 did not meet protocol standards and 32 had inadequate anesthesia. A chart review of the remaining 315 patients was undertaken to obtain surgical information not recorded in the original study. All patients were monitored with radial and pulmonary artery catheters. After surgery, patients were in a monitored setting for 48 to 72 hours and had graft function assessments hourly during the first 24 hours and then every 8 hours until discharge. RESULTS: Fifty-one patients were lost to follow-up (15 general, 22 spinal, 14 epidural). Baseline clinical characteristics were similar for the three groups except prior carotid artery surgery, which was more common in the spinal group. Indications for surgery were also similar except for a higher incidence of nonhealing ulcer in the epidural group. There were no differences among groups for 30-day graft patency with or without reoperation, 30-day graft occlusion, death, amputation, or length of hospital stay. CONCLUSION: These results suggest that the type of anesthetic given for femoral to distal artery bypass does not significantly affect 30-day occlusion rate, limb salvage rate, or hospital length of stay.

Aged↗
PubMed1997

Evaluation of the accuracy and response time of STAT-mode continuous cardiac output.

OBJECTIVES: This study was conducted to compare continuous cardiac output (CCO) with bolus thermodilution cardiac output (BTD) at steady state, and to compare the response time of STAT CCO with that of trend CCO, mean arterial pressure, and mixed venous oxygen saturation [SvO2] during an acute hemodynamic change. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Twenty-nine patients undergoing cardiac surgery or liver transplantation. INTERVENTIONS: STAT and trend CCO were compared with BTD cardiac output during steady state intraoperatively and postoperatively in the intensive care unit. Ten patients, who required epicardial pacing after cardiac surgery, were studied to compare the response time of STAT CCO with that of trend CCO, mean arterial pressure, and BvO2 after a 10% to 20% increase in pacing rate. MEASUREMENTS AND MAIN RESULTS: A total of 108 cardiac output data sets were analyzed at steady state. Steady state was defined as stable heart rate and mean arterial pressure (+/- 5%) and stable central venous pressure (+/- 2 mmHg) measured immediately before and after each data set. Cardiac output ranged from 2.3 to 8.5 L/min. The correlation between STAT CCO and BTD was r = 0.94, and for trend CCO and BTD was r = 0.94. The bies and precision for STAT CCO versus BTD were 0.06 L/min (Cl 95%: -0.08 to 0.18) and 0.61 L/min. The bias and precision for trend CCO versus BTD were 0.06 L/min (Cl 95%: -0.04 to 0.16) and 0.49 L/min. Eleven data sets were analyzed to study response time of STAT CCO, which was defined as the first time the percent change of the mean of each variable was significantly increased from baseline. Significant increases in mean arterial pressure and SvO2 were detected after 30 seconds (2.5%, p = 0.01) and 90 seconds (2.0%, p = 0.04), respectively. A significant increase in STAT CCO was reached at 270 seconds (4.4%, p = 0.005). Trend CCO tended to increase but did not reach statistical significance within 6 minutes. CONCLUSIONS: STAT and trend CCO are accurate and precise and show close agreement with BTD cardiac output at steady state. The faster algorithm of STAT CCO offers some advantage over trend CCO during an acute hemodynamic change. However, because of the averaging process for determining CCO, the response time of STAT CCO is slower than that of mean arterial pressure and SvO2.

Algorithms↗
PubMed1996

Effects of topical benzocaine and lignocaine on upper airway reflex sensitivity.

We studied the degree and duration of effect on upper airway reflex sensitivity of oral benzocaine lozenges, nebulised lignocaine and lignocaine sprayed onto the vocal cords under direct vision, using low concentrations of ammonia as a stimulus to upper airway receptors. Ten minutes after the administration of oral benzocaine 20 mg the threshold response of the upper airway to ammonia (NH3TR) had risen significantly from baseline mean (SEM) of 680 (95) to 975 (109) ppm of ammonia with a return to baseline values after 25 min (n = 8, p < 0.05, repeated measures of ANOVA; p < 0.001, t-test). A direct spray of lignocaine 100 mg onto the vocal cords resulted in a significant elevation in NH3TR from a baseline mean (SEM) of 665 (81) to a maximum of 1600 (88) ppm of ammonia with a significant elevation in the threshold persisting for 100 min (n = 7, p < 0.001, repeated measures of ANOVA; p < 0.05, t-test). The application of 4% nebulised lignocaine 4 ml significantly increased NH3TR from a baseline mean (SEM) of 770 (56) to a maximum of 1190 (63) ppm of ammonia with a significant elevation in the threshold persisting for 30 min (n = 8, p < 0.001, repeated measures of ANOVA; p < 0.05, t-test). The maximum elevations in NH3TR with the two methods of lignocaine delivery were significantly different (p < 0.01, 2-way ANOVA).

Administration, Oral↗
PubMed1995

Postoperative laryngeal competence. The laryngeal mask airway and tracheal tube compared.

We investigated the incidence of postoperative laryngeal incompetence in 40 patients undergoing lower limb arthroplasty. Patients were randomly allocated to one of two groups using a standardised general anaesthetic/muscle relaxant technique; in group A the patients' lungs were ventilated via a laryngeal mask airway and in group B via a tracheal tube. Following recovery from general anaesthesia, at a time when patients were considered safe for discharge back to the general ward, they were asked to swallow 20 ml of barium, and an immediate portable chest X ray was taken. The X rays were examined for evidence of tracheopulmonary aspiration. Contrary to previous studies the incidence of aspiration was low, occurring in only one patient. This aspiration was, however, clinically silent. The exact mechanism of this apparent laryngeal incompetence, which occurred in a patient from the tracheal tube group, is unclear. Due to the relatively small numbers of patients studied no conclusions can be drawn about the relative benefits of the use of the laryngeal mask airway with regard to postoperative laryngeal competence.

Aged↗
PubMedDate not supplied

Spinal anesthesia reduces oxygen consumption in diabetic patients prior to peripheral vascular surgery.

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate the effect of spinal anesthesia in VO2 in a uniform high-risk patient population and also the relationship between dermatomal level of block and VO2, neither of which has been investigated previously. METHODS: The effect of spinal anesthesia on VO2 was studied in 17 diabetic patients undergoing lower limb peripheral vascular surgery. Measurements were made before and 15 minutes after administration of a tetracaine spinal anesthetic. Values for VO2 and oxygen delivery (DO2) were derived from cardiac output as measured by thermodilution, hemoglobin concentration, and arterial and mixed venous blood gas analysis. The dermatomal level of the sensory block was determined by use of a hand-held nerve stimulator. RESULTS: Mean VO2 decreased by 27.7% (P = .001) (95% confidence limits, decrease of 22.4-90.4%). Mean DO2 and arterial blood gases were unchanged, and the mean postspinal oxygen extraction ratio (VO2/DO2) decreased by 20.5% (P = .002) (95% confidence limits, decrease of 9.1-32.3%). There was a relationship between changes in VO2 and sensory block height (P = .029). CONCLUSIONS: Spinal anesthesia in diabetic patients is associated with a reduction in VO2, the extent of which appears to be, at least in part, a function of the level of spinal sensory block.

Adult↗