Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1998
A survey on the intended purposes and perceived utility of preoperative cardiology consultations.
Cardiology consultations are often requested by surgeons and anesthesiologists for patients with cardiovascular disease. There can be confusion, however, regarding both the reasons for a consultation and their effect on patient management. This study was designed to determine the attitudes of physicians toward preoperative cardiology consultations and to assess the effect of such consultations on perioperative management. A multiple-choice survey regarding the purposes and utility of cardiology consultations was sent to randomly selected New York metropolitan area anesthesiologists, surgeons, and cardiologists. In addition, the charts of 55 consecutive patients aged >50 yr who received preoperative cardiology consultations were examined to determine the stated purpose of the consult, recommendations made, and concordance by surgeons and anesthesiologists with cardiologists' recommendations. Of the 400 surveys sent to each specialty, 192 were returned from anesthesiologists, 113 were returned from surgeons, and 129 were returned from cardiologists. There was substantial disagreement on the importance and purposes of a cardiology consult: intraoperative monitoring, "clearing the patient for surgery," and advising as to the safest type of anesthesia were regarded as important by most cardiologists and surgeons but as unimportant by anesthesiologists (all P < 0.05). Most surgeons (80.2%) felt obligated to follow a cardiologist's recommendations, whereas few anesthesiologists (16.6%) felt so obligated (P < 0.05). The most commonly stated purpose of the 55 cardiology consultations examined was "preoperative evaluation." Only 5 of these (9%) were obtained for patients in whom there was a new finding. Of the cardiology consultations, 40% contained no recommendations other than "proceed with case," "cleared for surgery," or "continue current medications." Recommendations regarding intraoperative monitoring or cardiac medications were largely ignored. ⋯ We conclude that there seems to be considerable disagreement among anesthesiologists, cardiologists, and surgeons as to the purposes and utility of cardiology consultations. A review of 55 consecutive cardiology consultations suggests that most of them give little advice that truly affects management.
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Anesthesia and analgesia · Oct 1998
The effect of hyperventilation and hyperoxia on cerebral venous oxygen saturation in patients with traumatic brain injury.
Eighteen head-injured patients undergoing hyperventilation were studied for changes in jugular venous oxygen saturation (SjvO2) and arteriovenous oxygen content difference (AVDO2) in response to changes in PaO2 and PaCO2. SjvO2 decreased significantly from 66% +/- 3% to 56% +/- 3% (mean +/- SD) when PaCO2 decreased from 30 to 25 mm Hg at a PaO2 of 100-150 mm Hg. SjvO2 values returned to baseline (66% +/- 2%) when PaCO2 was restored to 30 mm Hg. Repetition of the study at a PaO2 of 200-250 mm Hg produced a similar pattern. However, SjvO2 values were significantly greater with PaO2 within the range of 200-250 mm Hg (77% +/- 4% and 64% +/- 3%) than SjvO2 measured at a PaO2 of 100-150 mm Hg at PaCO2 values of both 30 and 25 mm Hg. AVDO2 also improved with a PaO2 of 200-250 mm Hg at each PaCO2 (P < 0.001). In conclusion, decreases in SjvO2 associated with decreases in PaCO2 may be offset by increasing PaO2. ⋯ The adequacy of cerebral oxygenation can be estimated in head-injured patients by monitoring jugular bulb oxygen saturation and the arteriovenous oxygenation content difference. Increasing the partial pressure of arterial oxygen above normal offset deleterious effects of hyperventilation on jugular bulb oxygen saturation and arteriovenous oxygenation content difference in head-injured patients.
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Anesthesia and analgesia · Oct 1998
Jet ventilation in upper airway obstruction: description and model lung testing of a new jetting device.
Patients with critical upper airway stenosis require a tracheotomy for corrective surgery. We describe a new transtracheal device that permits safe ventilation of these patients without tracheotomy. It is based on a coaxial bicannular design that allows "push-pull" ventilation by jetting gas through the inner cannula and applying suction through the outer cannula. It further allows monitoring of airway pressure, tidal volume, and end-tidal CO2. The device was placed in the "trachea" of an artificial lung, and the preparation was made airtight by sealing the proximal end of the trachea. Tidal volumes and their associated pressures were measured simultaneously at different parts of the airway at several lung compliances and airway resistance settings while varying the jet and suction pressures. A large range of tidal volumes was achieved at safe airway pressures using clinically relevant airway resistance and lung compliance settings. Airway pressures measured through the device correlated well with pressures measured directly in the airways at the same time. Tidal volumes, measured through a Wright respirometer in the suction line, exceeded actual values at high suction settings and decreased below actual values at low suction settings. This new form of jet ventilation allowed efficient ventilation of the artificial lung with a totally occluded upper airway. ⋯ Tracheotomy is required for surgery to relieve stridor because gas forced into the trachea at high pressures through a percutaneously placed needle (jetting) cannot be exhaled quickly enough for respiration. We describe a device that allows jetting in the stridorous patient by actively assisting expiration, thereby eliminating the tracheotomy requirement.
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Anesthesia and analgesia · Oct 1998
Posttreatment with propofol terminates lidocaine-induced epileptiform electroencephalogram activity in rabbits: effects on cerebrospinal fluid dynamics.
There are no controlled studies to determine whether propofol given after the onset of lidocaine-induced seizures (posttreatment) stops lidocaine-induced seizures. In this study, we determined whether posttreatment with propofol abolishes lidocaine-induced epileptiform electroencephalogram (EEG) activity as effectively as does midazolam, and cerebrospinal fluid (CSF) dynamics during lidocaine-induced epileptiform EEG activity and its treatment. EEG activity and CSF dynamics were determined in two groups of anesthetized rabbits at each of four experimental conditions: baseline, lidocaine-induced epileptiform activity, treatment with midazolam (n = 6) or propofol (n = 6), and return to baseline. The analog EEG signal was converted into a set of digital parameters using aperiodic analysis, and CSF dynamics were determined using ventriculocistemal perfusion. Propofol (3.8 +/- 1.3 mg/kg) stopped epileptiform activity, as did midazolam (2.0 +/- 1.7 mg/kg). The rates of CSF formation or reabsorption and resistances to CSF reabsorption or flow at the arachnoid villi did not differ among conditions or between groups. Our results indicate that propofol and midazolam both terminate epileptiform activity without changing CSF dynamics. ⋯ Propofol may be an alternative to benzodiazepines for treating lidocaine-induced epileptiform electroencephalogram activity in patients.