Anesthesia and analgesia
-
Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Comparative Study Clinical TrialThe UpsherScope in routine and difficult airway management: a randomized, controlled clinical trial.
The UpsherScope, a rigid fiberoptic laryngoscope, may facilitate tracheal intubation. We performed a randomized, controlled trial of tracheal intubation using the UpsherScope and compared the success rate with that of direct laryngoscopy. Three hundred patients were randomly assigned to either fiberoptic oral intubation using the UpsherScope (Group US, n = 148) or to direct laryngoscopy (Group DL, n = 152). No significant differences in airway variables were observed between the groups. US intubation was successful in 129 of 148 patients (87%). A second or third attempt was required in 15% and 3%, respectively, of the patients successfully intubated with US. The remaining patients were intubated using DL (n = 17) or the flexible fiberoptic bronchoscope (n = 2). The success rate of DL was significantly higher (97%; P < 0.05), with a second or third attempt required in only seven patients. Time needed to perform successful intubation was 50 +/- 41 s for the US group compared with 23 +/- 13 s for the DL group (P < 0.05). We found no advantage of the UpsherScope over direct laryngoscopy during routine and difficult airway management. Time needed, number of attempts required to perform intubation, and incidence of failure were significantly longer and higher in group US. ⋯ We studied tracheal intubation using the fiberoptic UpsherScope and compared the success rate with that of a control group of patients intubated using conventional laryngoscopy. No advantages of the new device were found. On the contrary, time needed, number of attempts required, and incidence of failure were even longer and higher.
-
Anesthesia and analgesia · Dec 1997
The effects of sevoflurane on cerebral hemodynamics during propofol anesthesia.
We investigated the cerebral hemodynamic effects of 0.5 and 1.5 minimum alveolar anesthetic concentration (MAC) sevoflurane during propofol anesthesia in 10 patients undergoing supratentorial tumor resection. All patients received a standardized anesthetic, and their lungs were ventilated with a mixture of air and oxygen to produce mild hypocapnia. Anesthesia was then maintained with a propofol infusion. Muscle relaxation was obtained by infusion of atracurium. A transcranial Doppler probe was used to measure red cell flow velocity in the right middle cerebral artery (Vmca). A right-sided jugular bulb catheter was inserted for sampling of jugular bulb blood. After a 30-min period of stabilization and before the start of surgery, baseline arterial and jugular bulb blood samples were drawn to define the arterial-venous oxygen content difference (AVDO2). Mean arterial pressure and Vmca were recorded. Sevoflurane (0.5 and 1.5 MAC) in oxygen/air was then administered, and all measurements were repeated. Administration of sevoflurane at 0.5 MAC did not change Vmca or AVDO2. Sevoflurane (1.5 MAC) did not change Vmca. There was an approximately 25% reduction in AVDO2 (P < 0.05). This suggests that during propofol anesthesia, although 1.5 MAC sevoflurane does not increase red blood cell velocity, there is a relative increase in flow with respect to metabolism. Administration of large-dose sevoflurane may be associated with a degree of luxury perfusion. ⋯ We investigated the cerebral hemodynamic effects of sevoflurane in patients undergoing neurosurgery. Small-dose sevoflurane (1%) did not change brain blood flow or oxygen consumption. Large-dose sevoflurane (3%) did not change flow velocity but reduced brain oxygen consumption by 25%. Sevoflurane may provide a degree of luxury perfusion.
-
Anesthesia and analgesia · Dec 1997
Comparative StudyArgon pneumoperitoneum is more dangerous than CO2 pneumoperitoneum during venous gas embolism.
We investigated the possibility of using argon, an inert gas, as a replacement for carbon dioxide (CO2). The tolerance of argon pneumoperitoneum was compared with that of CO2 pneumoperitoneum. Twenty pigs were anesthetized with enflurane 1.5%. Argon (n = 11) or CO2 (n = 9) pneumoperitoneum was created at 15 mm Hg over 20 min, and serial intravenous injections of each gas (ranging from 0.1 to 20 mL/kg) were made. Cardiorespiratory variables were measured. Transesophageal Doppler and capnographic monitoring were assessed in the detection of embolism. During argon pneumoperitoneum, there was no significant change from baseline in arterial pressure and pulmonary excretion of CO2, mean systemic arterial pressure (MAP), mean pulmonary artery pressure (PAP), or systemic and pulmonary vascular resistances, whereas CO2 pneumoperitoneum significantly increased these values (P < 0.05). During the embolic trial and from gas volumes of 2 and 0.2 mL/kg, the decrease in MAP and the increase in PAP were significantly higher with argon than with CO2 (P < 0.05). In contrast to CO2, argon pneumoperitoneum was not associated with significant changes in cardiorespiratory functions. However, argon embolism seems to be more deleterious than CO2 embolism. The possibility of using argon pneumoperitoneum during laparoscopy remains uncertain. ⋯ Laparoscopic surgery requires insufflation of gas into the peritoneal cavity. We compared the hemodynamic effects of argon, an inert gas, and carbon dioxide in a pig model of laparoscopic surgery. We conclude that argon carries a high risk factor in the case of an accidental gas embolism.
-
Anesthesia and analgesia · Dec 1997
Time-dependent changes in heart rate and pupil size during desflurane or sevoflurane anesthesia.
To better characterize alterations in autonomic function associated with prolonged anesthesia, we tested the hypothesis that the time-dependent effects of sevoflurane and desflurane differ. We studied seven male volunteers, each anesthetized for 8 h with 1.25 minimum alveolar anesthetic concentration desflurane on one study day and with 8 h sevoflurane on another. These volunteers did not undergo surgery and were minimally stimulated during the study. Measurements included blood pressure, heart rate, pupillary size and light reactivity, concentrations of serum catecholamines, and carbon dioxide production. Over time, heart rate and pupil size increased significantly. During 6 of the 14 anesthetics (45%), heart rate at some point exceeded 95 bpm; similarly, pupil size at some time exceeded 5 mm during 8 anesthetics (57%). In contrast, plasma catecholamine concentrations and carbon dioxide production remained unchanged, and blood pressure remained nearly constant. There are thus substantial time-dependent changes in autonomic functions during prolonged anesthesia, even in unstimulated, nonsurgical volunteers, but we could not detect a difference in these changes during desflurane compared with sevoflurane anesthesia. ⋯ Pupil size and heart rate changes are used to guide the delivery of anesthesia. In volunteers, pupil size and heart rate increased with increasing duration of constant desflurane or sevoflurane anesthesia. Thus, anesthetic duration alters heart rate and pupil size independent of surgery and changes in anesthetic delivery.