A Formula for Estimating the Appropriate Tube Depth for Intubation.

An estimation of the appropriate tubing depth for fixation is helpful to prevent inadvertent endobronchial intubation and prolapse of cuff from the vocal cord. A feasible estimation formula should be established. We measured the anatomical length of the upper-airway tract through the oral and nasal pathways on cephalometric radiographs and tried to establish the estimation formula from the height of the patient. The oral upper-airway tract was measured from the tip of the incisor to the vocal cord. The nasal upper-airway tract was measured from the tip of the nostril to the vocal cord. The tracts were smoothly traced by using software. The length of the oral upper-airway tract was 13.2 ± 0.8 cm, and the nasal upper-airway tract was 16.1 ± 0.9 cm. We found no gender difference ( p > .05). The correlations between the patients' height and the length of the oral and nasal upper-airway tracts were 0.692 and 0.760, respectively. We found that the formulas (height/10) - 3 (in cm) for oral upper-airway and (height/10) + 1 (in cm) for nasal upper-airway tract are the simple fit estimation formulas. The average error and standard deviation of the estimated values from the measured values were 0.50 ± 0.66 cm for the oral tract and 0.39 ± 0.63 cm for the nasal tract. Thus, considering the length of the intubation marker of each product (DM), we would like to propose the length of tube fixation as (height/10) + 1 + DM for nasal intubation and (height/10) - 3 + DM for oral intubation. In conclusion, the estimation formulas of (height/10) - 3 + DM and (height/10) + 1 + DM for oral and nasal intubation, respectively, are within almost 1 cm error in most cases.

Whole Blood Platelet Aggregation Test and Prediction of Hemostatic Difficulty After Tooth Extraction in Patients Receiving Antiplatelet Therapy.

When patients on antiplatelet therapy (APT) require minor invasive surgery, APT is usually continued to limit the risk of thrombosis. However, the possibility of hemostatic difficulties necessitates the monitoring of platelet aggregation to prevent unexpected bleeding. We examined whether whole blood aggregometry as a point-of-care testing (POCT) could be useful as a tool for predicting hemostatic difficulties. Sixty-five patients receiving APT and 15 patients who were not receiving APT were enrolled in the present study; all patients were scheduled to undergo a tooth extraction. Whole blood samples were obtained and were examined using multiple electrode aggregometry. The aggregometry was performed using arachidonic acid (AA), adenosine diphosphate (ADP), and thrombin receptor activating peptide. Hemostatic difficulty was defined as a need for more than 10 minutes of compression to achieve hemostasis. The AA test results were significantly lower in patients treated with aspirin (control: 97.7 [29.0] U, aspirin: 14.5 [7.2] U, P < .001). The ADP test results were also significantly lower in patients treated with a P2Y12 inhibitor (control: 77.7 [21.7] U, P2Y12 inhibitor: 37.3 [20.4] U, P < .01). Six of the examined cases exhibited hemostatic difficulties. The cutoff values for the prediction of hemostatic difficulty were 16.5 U for the AA test (sensitivity, 0.833; specificity, 0.508) and 21 U for the ADP test (sensitivity, 0.847; specificity, 0.500). Our study showed that whole blood aggregometry was useful as a POCT for the prediction of hemostatic difficulties after tooth extraction in patients receiving APT.

The Amount of Fluid Given During Surgery That Leaks Into the Interstitium Correlates With Infused Fluid Volume and Varies Widely Between Patients.

BACKGROUND: The revised Starling law suggests that intravenously infused fluid may leak into the interstitium and not remain in the intravascular space. This hypothesis is supported by clinical findings that postoperative weight gain is proportional to the amount of infused fluid. The distribution of intravenously administered fluid between the interstitium and intravascular space deserves evaluation, as postoperative weight gain because of intraoperative infusion is an important risk factor for postoperative adverse events. We quantitatively estimated fluid movement in patients undergoing orthognathic surgery by performing a volume kinetic study using hemoglobin concentration as a marker of dilution. METHODS: Forty-one patients scheduled to undergo orthognathic surgery were enrolled in this study. The arterial hemoglobin concentration was measured at each procedural step. Acute normovolemic hemodilution was induced by withdrawing 400 mL of blood followed by the infusion of a known amount of hydroxyethyl starch, enabling the initial blood volume to be estimated. The dilution rate of the arterial hemoglobin concentration enabled the volume of fluid in the intravascular space to be quantified. The fluid volume that leaked into the interstitium was then calculated based on the change in the estimated intravascular plasma volume. RESULTS: The blood volume estimated via this method was close to the value derived from a previously published formula. The mean volume of crystalloid infused as a maintenance fluid was 2062 ± 408 mL, ranging from 1220 to 3050 mL. None of the cases required blood product transfusion. The amount of infused fluid that remained intravascular varied widely from 2.0 to 35.7 mL/kg (mean, 12.0 ± 8.2 mL) after surgery, corresponding to 5.3% to 95.7% of the infused volume. The change in intravascular fluid volume during surgery was not strongly correlated with the infusion amount (Pearson correlation analysis: r = -0.05, P = .75, -0.44 < ρ ≤ 0.35, confidence intervals; Spearman correlation analysis: r = -0.14, P = .38, -0.51 < ρ ≤ 0.27). However, the amount of fluid that leaked into the interstitium during surgery did correlate with the infusion amount (Pearson correlation analysis: r = 0.42, P = .01, 0.03 < ρ ≤ 0.70; Spearman correlation analysis: r =0.45, P = .003, 0.07 < ρ ≤ 0.72). CONCLUSIONS: We found that the increase in intravascular fluid volume caused by intravenous fluid administration was not correlated strongly with the volume of infused fluid. Instead, the amount of fluid leakage into the interstitial space depended on the infused fluid volume. This clinical result supports the revised Starling law, which suggests that intravascular fluid may often leak into the interstitium. More work is needed to better understand the factors governing leakage of infused fluid into the interstitial space.