Anesthesia and analgesia
-
Anesthesia and analgesia · Jul 2002
Comparative Study Clinical TrialRepeated deflation of a gas-barrier cuff to stabilize cuff pressure during nitrous oxide anesthesia.
Although a nitrous oxide (N(2)O) gas-barrier cuff effectively limits the increase of cuff pressure during N(2)O anesthesia, there are few data assessing whether an N(2)O gas-barrier cuff is more beneficial for stabilizing intracuff pressure than standard endotracheal tubes when cuffs are repeatedly deflated to stabilize pressure during N(2)O anesthesia. In the present study, the pressure of air-filled standard-type cuffs (Trachelon; Terumo, Tokyo, Japan) and N(2)O gas-barrier type endotracheal tube cuffs (Profile Soft-Seal Cuff [PSSC]; Sims Portex, Kent, UK) was measured during 67% N(2)O anesthesia (n = 8 in each), during which the cuffs were repeatedly deflated every 30 min (Trachelon) or 60 min (PSSC) for the first 3 or 4 h. After aspirating the cuffs for 3 h, the cuff pressure exceeded 22 mm Hg in more than half of the patients in both groups. However, aspiration of the cuffs for 4 h decreased the maximal cuff pressure between deflation intervals in both groups (P < 0.01 for each), and increased the intracuff N(2)O concentration (P < 0.0001 for each). After deflating the cuffs over 4 h, the cuff pressure in both groups never exceeded 22 mm Hg during the subsequent 3 h, and intracuff N(2)O concentrations did not significantly change. Therefore, deflation of cuffs for 4 h during N(2)O anesthesia sufficiently stabilized cuff pressure and equilibrated the intracuff N(2)O concentrations in both groups. The use of the PSSC endotracheal tube might be more practical because of the smaller number of cuff deflations required, but the PSSC does not reduce the duration of cuff deflations to stabilize the pressure. ⋯ We demonstrated that the N(2)O concentration and pressure in the N(2)O-barrier Profile Soft-Seal Cuff stabilized when the cuff was aspirated once an hour for 4 h during N(2)O anesthesia. The Profile Soft-Seal Cuff might be easier to use in clinical practice than standard endotracheal tubes because of the smaller number of cuff deflations required.
-
Anesthesia and analgesia · Jul 2002
Case ReportsThe use of the intubating laryngeal mask endotracheal tube with intubating devices.
Despite adequate visualization of the vocal cords using specialized airway devices, anatomical factors and the physical characteristics of the tube may cause difficulty when performing endotracheal intubation. The endotracheal tube designed for use with the intubating laryngeal mask airway may facilitate intubation in these circumstances.
-
Anesthesia and analgesia · Jul 2002
Clinical TrialMyocardial ischemia and cytokine response are associated with subsequent onset of infections after noncardiac surgery.
Postoperative myocardial ischemia (POMI) is prevalent among patients after major noncardiac surgery. Surgery, as well as POMI, may modulate the immune system, potentially worsening patient outcome. We sought to investigate the modulation of soluble interleukin (IL)-6 and IL-10 by POMI and its association with increased postoperative infection rates. Two-hundred-three patients undergoing elective major abdominal, vascular, and orthopedic surgery participated in this prospective observational study. Perioperative management was standardized. Hemodynamic variables were kept within 20% of baseline. POMI was assessed by Holter electrocardiography starting at least 8 h before the induction of anesthesia and continued until 96 h after surgery. Twelve-lead electrocardiograms, cardiac enzymes, and immune variables were obtained at the time of admission to the hospital, before surgery, before the induction of anesthesia, after surgery, at the time of admission to the intensive care unit, and 6, 12, 18, 24, 36, 48, 72, 96, 120, 144, and 168 h after surgery. Infections were diagnosed according to the Centers for Disease Control criteria. The incidence of POMI was 27%, and the majority of cases (76%) occurred within the first 24 h after surgery. IL-6 and IL-10 levels significantly increased during surgery but did not differ between the POMI and Non-POMI groups. However, in the subset of patients who developed severe infections or sepsis (n = 47) a median of 3 days (range, 1-8 days) after surgery, the intraoperative increases of IL-6 and IL-10 in the POMI group were, respectively, 3 and 10 times higher compared with the increase in the Non-POMI group. By using a multifactorial analysis in these patients with severe infections, the type of surgical trauma was associated with an increased IL-6 response, whereas the increase in IL-10 was attributed to POMI. These findings suggest that immediate cytokine responses due to POMI and type of surgery might be relevant for the later onset of severe infections and sepsis. ⋯ Postoperative myocardial ischemia (POMI) occurred in 27% of patients after major noncardiac surgery. This was associated with an immediate augmented cytokine response in the first 12 h after surgery in patients who developed severe infections or sepsis 3 days later. POMI was associated with an increased interleukin (IL)-10 response, whereas IL-6 was associated with the type of surgery.
-
Anesthesia and analgesia · Jul 2002
Modeling the effect of progressive endotracheal tube occlusion on tidal volume in pressure-control mode.
A recognized hazard of prolonged endotracheal intubation is progressive airway occlusion resulting from deposition of secretions on the inner surface of the endotracheal tube (ETT). When volume-controlled ventilation is used, progressive ETT occlusion may be detected by monitoring the difference between peak and plateau airway pressures. In pressure-controlled modes, however, inspiratory airway pressures are preset and thus cannot act as a warning indicator. Instead, changes in delivered tidal volumes may aid the diagnosis of ETT occlusion. To determine whether tidal volume monitoring effectively detects progressive ETT occlusion, we mathematically modeled the response of a ventilator operating in pressure-controlled mode to increasing airway resistance. To corroborate our model, we then bench-tested the Siemens 300 and Puritan-Bennett 7200 ventilators by using a test lung and a series of ETTs ranging in size from 9.0 to 3.5 mm inner diameter to simulate progressive occlusion. We found that when pressure-controlled mode was used, progressive ETT occlusion did not reduce delivered tidal volumes until occlusion was nearly complete. We conclude that prolonged use of pressure-controlled mode may allow significant ETT obstruction to build up undetected, risking complete ETT occlusion and complicating the perioperative care of patients ventilated with this mode. ⋯ Although increasing airway pressures during volume-controlled ventilation allow early recognition of endotracheal tube (ETT) obstruction, airway pressures with pressure-controlled ventilation are fixed. We found during tests of two intensive care unit ventilators that although ETT obstruction reduces delivered tidal volumes during pressure-controlled ventilation, reductions do not occur until occlusion is advanced.
-
We studied the incidence of awareness and explicit recall during general anesthesia in outpatients versus inpatients undergoing surgery. During a 14.5-mo period, we structurally interviewed 1500 outpatients and 2343 inpatients. Among outpatients, there were five cases of awareness and recall (one with clear intraoperative recollections and four with doubtful intraoperative recollections). Of the inpatients, six reported awareness and recall (three with clear and three with doubtful intraoperative recollections). The incidence of clear intraoperative recollections was 0.07% in outpatients and 0.13% in inpatients. The difference in the incidence was not significant. Among outpatients, those with awareness and recall were given smaller doses of sevoflurane than those without awareness and recall (P < 0.05). In conclusion, awareness and recall are rare complications of general anesthesia, and outpatients are not at increased risk for this event compared with inpatients undergoing general anesthesia. ⋯ Rapid recovery from general anesthesia is a crucial element of outpatient surgery. However, this practice may predispose a patient to receive less anesthetic, with increased risk for awareness and recall. We have shown that outpatients undergoing an operation using general anesthesia are not at increased risk for awareness compared with inpatients.