Optimal external laryngeal manipulation: modified bimanual laryngoscopy.

OBJECTIVES: External laryngeal manipulation (ELM) is commonly used to facilitate laryngeal view during direct laryngoscopy. We evaluated the effectiveness of the newly modified bimanual laryngoscopy, which involves a direct guidance of an assistant's hand by a laryngoscopist, to optimize laryngeal exposure during direct laryngoscopy compared with conventional bimanual laryngoscopy. METHODS: A total of 78 adult patients were included. Patients were randomly allocated to 1 of 2 groups: group C (ELM using conventional bimanual laryngoscopy) or group M (ELM using the modified bimanual laryngoscopy). The difference in percentage of glottic opening scores after the application of ELM, the number of ELM attempts, and the time taken to obtain the best laryngeal view during ELM were recorded. RESULTS: The differences in the percentage of glottic opening score before and after the initial attempt of ELM significantly improved in group M compared with group C (40% [30%-50%] vs 30% [15%-35%], median [interquartile range], respectively; P < .001). The success rate of achieving the best laryngeal view on the first attempt was higher in group M than in group C (87% vs 36%, respectively; P < .001). The time taken for obtaining the best laryngeal view after the first ELM attempt was significantly shorter in group M than in group C (3 [3-4] vs 7 [4-8] seconds, median [interquartile range], respectively; P < .001). CONCLUSION: The modified bimanual laryngoscopy is more effective for obtaining the optimal laryngeal view on the first attempt compared with the conventional bimanual laryngoscopy.

Acute normovolemic hemodilution can aggravate neurological injury after spinal cord ischemia in rats.

BACKGROUND: Acute normovolemic hemodilution (ANH) is currently performed during thoracoabdominal aortic surgery. However, the effects of ANH on spinal cord ischemic injury are currently unknown. Because hemodilution below a certain level of hematocrit (Hct) aggravates the neurological damage after cerebral ischemia, we hypothesized that ANH may increase neurological damage after spinal cord ischemia. The aim of these experiments was to determine the effects of ANH on spinal cord ischemic injury. METHODS: Thirty male Sprague-Dawley rats were randomly assigned to 1 of the following 3 groups: no hemodilution (group C), target Hct level of 30% (group HD30), and target Hct level of 25% (group HD25). ANH was performed upon withdrawal of blood and simultaneous replacement with the same volume with hydroxyethyl starch. Spinal cord ischemia and reperfusion were induced by using a balloon-tipped catheter placed in the descending thoracic aorta, and changes in mean arterial blood pressure were recorded. Neurological function of the hindlimbs was evaluated for 7 days and recorded using a motor deficit score (MDS) (0 = normal; 5 = complete paraplegia). The number of motor neurons within the spinal cord was counted after final MDS evaluation. RESULTS: Group HD25 developed hypotension during the latter part of the ANH procedure. Group C and group HD30 experienced 3 minutes of reperfusion hypotension, whereas 6 minutes of hypotension was observed in group HD25. Two rats in group HD25 died during the experimental period. Seven days after reperfusion, the MDS of group C, group HD30, and group HD25 was 1.0 (0.5-2.0), 1.0 (0.5-2.0), and 4.0 (2.8-4.2) (median [95% confidence interval]), respectively. Group HD25 showed significantly higher MDS compared with group C (corrected P = 0.0018; 95% CI for median difference = 1.0-3.5). Motor neuron numbers in the anterior horns of group C, group HD30, and group HD25 were 26.5 (25.0-27.5), 23.5 (22.0-26.5), and 12.5 (8.4-16.6) (median [95% CI]), respectively. Motor neuron numbers of group HD25 were significantly lower than those of group C (corrected P < 0.0001; 95% CI for median difference = 9.0-18.0). CONCLUSION: The results of the present study indicate that intraoperative ANH to an Hct of 25%, combined with coincident hypotension, caused a delayed recovery of baseline mean arterial blood pressure during the reperfusion period and aggravated neurological outcome after spinal cord ischemia.

Magnesium sulfate does not protect spinal cord against ischemic injury.

OBJECTIVE: We tested various doses of MgSO(4) to investigate the effect of Mg on a spinal cord ischemia. METHODS: Rats were treated with either MgSO(4) (30, 100, or 300 mg/kg; group Mg(low), group Mg(medium), group Mg(high), respectively, n = 10 for each) or saline (control group; n = 10) before ischemia. Spinal cord ischemia was induced using a balloon-tipped catheter placed on proximal descending aorta. During surgery, hemodynamic variables were recorded before ischemia, during aortic occlusion and after reperfusion. Neurologic function was assessed using the motor deficit index (MDI; 0 = normal, 6 = complete paralysis) until seven days after reperfusion, and histologic examination of spinal cord was performed. RESULTS: After reperfusion, the mean arterial pressure in the group Mg(high) was significantly lower than other groups. Compared to the control group, the groups Mg(low) and Mg(medium) did not show any difference in MDI and the group Mg(high) showed significantly higher MDI. The number of normal motor neurons was similar among other groups except the group Mg(high) had a significantly fewer normal motor neurons. CONCLUSIONS: Intravenous MgSO(4) with low or medium dose (30, or 100 mg/kg) did not improve neurological injury following spinal cord ischemia. Furthermore, higher dose of MgSO(4) (300 mg/kg) resulted in hemodynamic instability and aggravated neurologic outcome.

The effect of retrograde autologous priming of the cardiopulmonary bypass circuit on cerebral oxygenation.

OBJECTIVE: The aim of this study was to investigate the effect of retrograde autologous priming (RAP) of the cardiopulmonary bypass (CPB) circuit on cerebral oxygenation. DESIGN: A retrospective cohort study. SETTING: A university hospital. PARTICIPANTS: Ninety-four patients undergoing CPB. INTERVENTIONS: CPB was primed with a RAP technique in the RAP group (n = 46) or with a conventional technique in the control group (n = 48). MEASUREMENT AND MAIN RESULTS: Cerebral oxygenation was monitored by measuring the regional cerebral oxygen saturation (rSO(2)). The rSO(2) and Hct values were compared between the groups during surgery. During the CPB period, the RAP group showed significantly higher values for rSO(2) (%) (immediately after the onset of CPB: 51.3 ± 8.4 and 56.3 ± 8.3; 30 minutes after the onset of CPB: 56.3 ± 5.1 and 59.7 ± 7.0; control group and RAP groups, respectively; p < 0.01 for each) and Hct (%) (immediately after the onset of CPB: 21.1 ± 3.7 and 23.1 ± 3.3; 30 minutes after the onset of CPB: 21.9 ± 3.7 and 23.3 ± 2.3; control group and RAP group, respectively; p < 0.02 for each). However, the 2 groups did not differ in rSO(2) (%) (67.2 ± 6.3 and 67.8 ± 6.4) or Hct (%) (27.8 ± 4.1 and 28.9 ± 3.6, control group and RAP group, respectively) at the end of the surgery. CONCLUSIONS: The application of RAP to CPB limits the degree of hemodilution and improves cerebral oxygenation during CPB. The present findings suggest a potential benefit of RAP from a neurologic aspect.

A comparison of lighted stylet (Surch-Lite) and direct laryngoscopic intubation in patients with high Mallampati scores.

BACKGROUND: A lighted stylet is an effective alternative to a direct laryngoscope and has been reported to be particularly useful in patients with difficult airways. A high Mallampati class indicates poor visibility of the oropharyngeal structures. Because a lighted stylet does not require direct oropharyngeal visualization, we hypothesized that the lighted stylet would be easier to use than a direct laryngoscope in patients with a high Mallampati score. To examine our hypothesis, we performed a prospective, randomized study comparing a lighted stylet (Surch-Lite) with direct laryngoscopy in patients with high Mallampati scores. Success rate, time required for intubation, and hemodynamic changes were compared. METHODS: Mallampati Class III patients were enrolled and were randomly assigned to the Surch-Lite group (Group SL) or the direct laryngoscopy group (Group DL). Patients' tracheas were intubated with the randomly selected intubation device after induction of general anesthesia. Heart rate (HR) and mean arterial blood pressure were measured immediately before and every 30 s after intubation for 5 min. The time to intubation and success rate were recorded. Postoperative pharyngolaryngeal complaints were also assessed. RESULTS: Thirty patients were enrolled in each group. The success rate on the first attempt was significantly higher in Group SL (29 of 30) than in Group DL (24 of 30). The difference between maximal HR and baseline HR was significantly higher in Group DL (25 +/- 13 bpm) than in Group SL (16 +/- 10 bpm). The change in mean arterial blood pressure was also higher in Group DL (38 +/- 14 mm Hg) than in Group SL (20 +/- 13 mm Hg). The time to intubation was significantly shorter in Group SL (12 +/- 6 s) than in Group DL (17 +/- 12 s). Postoperative pharyngolaryngeal complaints were not significantly different between the two groups. CONCLUSIONS: The Surch-Lite showed a higher success rate on the first intubation attempt and produced an attenuated hemodynamic response to endotracheal intubation of patients with high Mallampati score. Thus, the Surch-Lite is an effective alternative to direct laryngoscopy in these patients.