Anesthesia and analgesia
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Anesthesia and analgesia · Apr 1992
ReviewPreoperative cardiac evaluation for noncardiac surgery: a functional approach.
The preoperative assessment of the high risk patient undergoing noncardiac surgery has traditionally been based on history, physical examination, and preoperative testing. We propose a method of assessing preoperative risk based on the presentation of coronary artery disease, exercise tolerance, and extent of the surgical procedure. Since this is an evolving field, as new information and perioperative management techniques become available, the preoperative evaluation of the high risk patient will change. ⋯ In the patient at risk of but without overt symptoms of coronary artery disease, the number of clinical risk factors can determine the probability of coronary artery disease in the individual patient. The decision to perform preoperative revascularization should be based on its anticipated improvement of both the short- and long-term prognosis of the patient considering the risk of such procedures. The objective assessment of LVEF should be performed in patients with a poor exercise tolerance with either a high risk of perioperative ischemia or a suspicion of cardiomyopathy.
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Anesthesia and analgesia · Apr 1992
Complications occurring in the postanesthesia care unit: a survey.
To identify and quantitate complications occurring in the postanesthesia care unit (PACU), a prospective study evaluated 18,473 consecutive patients entering a PACU at a university teaching hospital. Using a standardized collection form, the incidence of intraoperative and PACU complications was determined. The combined PACU and intraoperative complication rate was 26.7%. ⋯ In patients experiencing a major cardiovascular complication, for example, variables associated with a greater risk of developing any PACU complications were ASA physical status (status II), duration of anesthesia (2-4 h), anesthetic technique, emergency procedures, and certain types of surgical procedures (orthopedic or abdominal). For patients admitted with a temperature of less than 35 degrees C the duration of the PACU stay was 152 +/- 46 min compared with 116 +/- 65 min for patients with a temperature greater than or equal to 36 degrees C (P less than 0.01). In conclusion, events occurring during the PACU period continue to be a source of patient morbidity.
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Anesthesia and analgesia · Apr 1992
Comparative StudyQuantification of the jet function of a jet stylet.
The concept and use of a jet stylet as an additional safety measure during tracheal extubation of patients in whom subsequent ventilation and/or reintubation of the trachea may be difficult has recently been described. If jet ventilation through a jet stylet could provide for effective gas exchange, it would allow additional time to assess the need for reintubation of the trachea. We determined the tidal volumes (measured by integrating a pneumotachograph flow signal) that 50-psi jet ventilation, at an inspiratory to expiratory time ratio of 1:1 (unit of time = 1 s), could deliver through small, medium, and large Sheridan tube exchangers into an in vitro lung model that had lung compliances of 50 and 30 mL/cm H2O (six experimental permutations). ⋯ Decreased lung compliance caused decreased VT and end-expiratory volume for all six experimental conditions. The largest VT and minute ventilation (VE) generated were 1680 mL and 51.6 L/min (large tube exchanger, high lung compliance) and the lowest VT and VE were 440 mL and 13.2 L/min (small tube exchanger, low lung compliance), respectively. These findings validate the term "jet stylet" for all three tube exchangers as even the smallest tube exchanger, coupled with a low lung compliance, can provide a VE consistent with total ventilatory support for most clinical situations.
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Anesthesia and analgesia · Apr 1992
Comparative StudyComparison of the endotracheal tube and laryngeal mask in airway management by paramedical personnel.
An evaluation of the laryngeal mask airway (LMA) as a means of airway support when used by paramedical personnel was performed. Forty medical and paramedical students attempted to intubate the tracheas of 40 healthy anesthetized adults with the LMA and a cuffed endotracheal tube (ETT). The number of attempts to achieve correct placement and the time taken to adequately ventilate the lungs were recorded for both devices. ⋯ Five students were unable to intubate the trachea after three attempts with the ETT, but all positioned the LMA satisfactorily on their first try in a mean time of 40 s. We conclude that unskilled operators with minimal training can safely and successfully ventilate unconscious patients more rapidly using the LMA than the ETT. These results suggest the LMA should be available in all areas where resuscitation is performed.
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Anesthesia and analgesia · Apr 1992
Enhancement of bupivacaine sensory blockade of rat sciatic nerve by combination with phenol.
We sought to determine whether the addition of phenol would enhance a bupivacaine nerve block. The effects on nerve conduction of bupivacaine (0.125%) and phenol (0.5%), singly and combined, were evaluated in vivo on the rat sciatic nerve. Three groups of 10 animals each were used. ⋯ The analgesia score derived from the hot-plate test was more and persisted longer for the combination treatment than for either 0.125% bupivacaine or 0.5% phenol given singly; e.g., the average sensory block score after 150 min for the combination treatment was 1.0 compared with 0.1 for either bupivacaine or phenol given alone (P = 0.003). Analysis of the areas under the sensory score-time curves also demonstrated enhanced blockade from the combination treatment, which would be consistent with a synergism of the separate Na(+)-channel blocking effects of charged and uncharged local anesthetics. These findings may suggest other candidates for clinically useful combinations of amine and neutral local anesthetics.