Anesthesia and analgesia
-
Anesthesia and analgesia · Aug 2003
Clinical Trial Controlled Clinical TrialThe relationship between expired concentration of sevoflurane and sympathovagal tone in children.
In children, sevoflurane depresses parasympathetic tone during induction more than halothane. The effects of sevoflurane on parasympathetic activity could explain the difference in heart rate (HR) changes described between infants and children. In this study, we sought to determine the relationship between the end-tidal concentration of sevoflurane and sympathetic and parasympathetic tone in children by spectral analysis of RR intervals. Thirty-three children, ASA physical status I, who required elective surgery were studied. In 10 children (Group A), recordings were performed while gradually decreasing the inspired sevoflurane concentration from 8% to the beginning of clinical awakening. In 23 other children (Group B), recordings were performed while children were awake and at a steady-state of 1 and 2 minimum alveolar anesthetic concentration of sevoflurane. A time-varying autoregressive modeling of the interpolated RR sequences was performed, and spectral density in low-frequency (LF; 0.04-0.15 Hz) and high-frequency (HF; 0.15-0.55 Hz) bands was calculated. In Group A, HR slowing paralleled the decrease in expired sevoflurane concentration. Conversely, the decrease in expired concentration of sevoflurane led to an increase in systolic blood pressure (SBP), HF, LF, and LF/HF. The increase in LF/HF preceded the increase in HF. In Group B, the baseline HF power spectrum and normalized values HFnu (HFnu = HF/LF + HF) were significantly increased in children older than 3 yr. Changes in HR induced by sevoflurane were negatively correlated with baseline HF and HFnu (R(2) = 0.6; P < 0.001). These results demonstrate that withdrawal of parasympathetic tone is the main determinant for the change in HR induced by sevoflurane. ⋯ The effects of sevoflurane on parasympathetic activity could explain the difference in heart-rate changes described between infants and children during induction. This study describes the changes in heart rate and its variability induced by sevoflurane in children and shows that these changes are related to parasympathetic tone before the induction of anesthesia.
-
Anesthesia and analgesia · Aug 2003
Randomized Controlled Trial Multicenter Study Clinical TrialDiaspirin-crosslinked hemoglobin reduces blood transfusion in noncardiac surgery: a multicenter, randomized, controlled, double-blinded trial.
In this randomized, prospective, double-blinded clinical trial, we sought to investigate whether diaspirin-crosslinked hemoglobin (DCLHb) can reduce the perioperative use of allogeneic blood transfusion. One-hundred-eighty-one elective surgical patients were enrolled at 19 clinical sites from 1996 to 1998. Selection criteria included anticipated transfusion of 2-4 blood units, aortic repair, and major joint or abdomino-pelvic surgery. Once a decision to transfuse had been made, patients received initially up to 3 250-mL infusions of 10% DCLHb (n = 92) or 3 U of packed red blood cells (PRBCs) (n = 89). DCLHb was infused during a 36-h perioperative window. On the day of surgery, 58 of 92 (64%; confidence interval [CI], 54%-74%) DCLHb-treated patients received no allogeneic PRBC transfusions. On Day 1, this number was 44 of 92 (48%; CI, 37%-58%) and decreased further until Day 7, when it was 21 of 92 (23%; CI, 15%-33%). During the 7-day period, 2 (1-4) units of PRBC per patient were used in the DCLHb group compared with 3 (2-4) units in the control patients (P = 0.002; medians and 25th and 75th percentiles). Mortality (4% and 3%, respectively) and incidence of suffering at least one serious adverse event (21% and 15%, respectively) were similar in DCLHb and PRBC groups. The incidence of jaundice, urinary side effects, and pancreatitis were more frequent in DCLHb patients. The study was terminated early because of safety concerns. Whereas the side-effect profile of modified hemoglobin solutions needs to be improved, our data show that hemoglobin solutions can be effective at reducing exposure to allogeneic blood for elective surgery. ⋯ In a randomized, double-blinded red blood cell controlled, multicenter trial, diaspirin-crosslinked hemoglobin spared allogeneic transfusion in 23% of patients undergoing elective noncardiac surgery. The observed side-effect profile indicates a need for improvement in hemoglobin development.
-
Anesthesia and analgesia · Aug 2003
Comparative StudyDifficult tracheal intubation is more common in obese than in lean patients.
Whether tracheal intubation is more difficult in obese patients is debatable. We compared the incidence of difficult tracheal intubation in obese and lean patients by using a recently validated objective scale, the intubation difficulty scale (IDS). We studied 134 lean (body mass index, <30 kg/m2) and 129 obese (body mass index, >or=35 kg/m2) consecutive patients. The IDS scores, categorized as difficult intubation (IDS >or=>5) or not (IDS <5), and the patient data, including oxygen saturation (SpO2) while breathing oxygen, were compared between lean and obese patients. In addition, risk factors for difficult intubation were determined in obese patients. The IDS score was >or=5 in 3 lean and 20 obese patients (P = 0.0001). A Mallampati score of III-IV was the only independent risk factor for difficult intubation in obese patients (odds ratio, 12.51; 95% confidence interval, 2.01-77.81), but its specificity and positive predictive value were 62% and 29%, respectively. SpO2 values noted during intubation were (mean +/- SD) 99% +/- 1% (range, 91%-100%) and 95% +/- 8% (range, 50%-100%) in lean and obese patients, respectively (P < 0.0001). We conclude that difficult intubation is more common among obese than nonobese patients. None of the classic risk factors for difficult intubation was satisfactory in obese patients. The high risk of desaturation warrants studies to identify new predictors of difficult intubation in the obese. ⋯ We report a difficult intubation rate of 15.5% in obese patients and 2.2% in lean patients. None of the risk factors for difficult intubation described in the lean population was satisfactory in the obese patients. We also report a high risk of desaturation in obese patients with difficult intubation.
-
Anesthesia and analgesia · Aug 2003
Randomized Controlled Trial Clinical TrialThe effect of small dose fentanyl on the emergence characteristics of pediatric patients after sevoflurane anesthesia without surgery.
We designed this study to measure the effect of a small dose of IV fentanyl on the emergence characteristics of pediatric patients undergoing sevoflurane anesthesia without any surgical intervention. Thirty-two ASA physical status I or II pediatric outpatients receiving sevoflurane anesthesia for magnetic resonance imaging scans were enrolled and assigned in a random and double-blinded manner to receive either placebo (saline) or 1 micro g/kg IV fentanyl 10 min before discontinuation of their anesthetic. The primary outcome measure was the percentage of patients with emergence agitation. We also evaluated the duration of agitation and time to meet hospital discharge criteria. Patients who received fentanyl had a decreased incidence of agitation (12% versus 56%) when compared with placebo. There was no significant difference in time to meet hospital discharge criteria. We conclude that the addition of a small dose of fentanyl to inhaled sevoflurane anesthesia decreases the incidence of emergence agitation independent of pain control effects. ⋯ The addition of a small dose of fentanyl given to patients undergoing nonsurgical sevoflurane anesthesia resulted in a significant decrease in emergence agitation in a prospective, randomized, and controlled trial involving pediatric patients.
-
Anesthesia and analgesia · Aug 2003
The bispectral index declines during neuromuscular block in fully awake persons.
Using an Aspect A-1000 BIS monitor, researchers demonstrated a drop in Bispectral Index Score in awake, paralysed volunteers to low values ranging from 9 to 64.
pearl