A comparison of the reliability of two techniques of left double-lumen tube bronchial cuff inflation in producing water-tight seal of the left mainstem bronchus.

UNLABELLED: A double-lumen endobronchial tube (DLT) bronchial cuff inflation technique that reliably ensures effective water-tight isolation of the two lungs has not been determined. In this study, 20 patients undergoing thoracic surgery requiring a left DLT had the bronchial cuff of the DLT inflated by one of two techniques. In Group 1, the cuff was inflated to produce an air-tight seal of the left bronchus using the underwater seal technique. In Group 2, the cuff was inflated to a pressure of 25 cm H2O. After bronchial cuff inflation in both groups, water-tight bronchial seal was tested by instilling 2 mL of 0.01% methylene blue (MB) above the bronchial cuff of the DLT. Fifteen minutes later, fiberoptic bronchoscopy was performed via the bronchial lumen of the DLT to determine whether MB had seeped past the bronchial cuff. Cuff volume was 0.75+/-0.64 and 0.76+/-0.46 mL, cuff pressure was 30.1+/-27.0 and 25.0+/-0.0 cm H2O (mean+/-SD), and MB was positively identified in two and five patients in Groups 1 and 2, respectively. The difference in cuff volume and pressure and the higher MB seepage in Group 2 compared with Group 1 was not statistically significant. In both groups, MB seepage occurred only when the bronchial cuff volume was <1 mL and when the patients were positioned in the left lateral decubitus position. These findings suggest that the risk of aspiration is greatest when the DLT is positioned in the dependent lung and when the bronchial cuff volume is <1 mL. IMPLICATIONS: Water-tight sealing of the left bronchus by DLT bronchial cuff was tested after cuff inflation using two different techniques. Neither air-tight bronchial seal nor cuff pressure of 25 cm H2O guaranteed protection against aspiration. The risk of aspiration was greatest when the DLT was positioned in the dependent lung and when the bronchial cuff volume was < 1 mL.

Tension pneumothorax precluding laparoscopic repair of diaphragmatic hernia.

Pneumothorax can result from laparoscopic procedures in the abdomen. Usually, pneumothoraxes are mild and asymptomatic and do not require conversion to an open procedure. We report a case of tension pneumothorax that developed during the course of a laparoscopic repair of a diaphragmatic hernia. In this patient, the tension pneumothorax did not respond to conventional means of therapy and required conversion to a laparotomy. A large diaphragmatic hernia with communication between the peritoneal and pleural cavities may be a contraindication to minimally invasive laparoscopic procedures.

The relationship between left mainstem bronchial diameter and patient size.

Knowledge of a patient's left mainstem bronchial diameter would provide a useful guide to choosing the appropriate double-lumen tube (DLT) size for that patient. Therefore, the authors investigated the possibility that left bronchial diameter could be predictably estimated from a patient's size and sex. The routine preoperative chest X-rays of 100 adult male and female patients of known age, height, and weight were examined. The left bronchial diameter was measured on the posteroanterior (PA) chest x-ray, and a formula was used to correct for the magnification of intrathoracic structures encountered on the PA view. Multiple linear regression analysis was used to determine whether one or more of the variables (age, sex, height, weight, and body surface area) had a predictable relationship to the left bronchial diameter. The left mainstem bronchial diameter in men and women (mean +/- SD/range) was 12.4 +/- 1.5 mm/9.5 to 15.5 mm, and 10.7 +/- 1.0 mm/9.0 to 14.0 mm, respectively. In female patients, none of the variables was significantly correlated with bronchial diameter. In male patients, age (p = 0.013) and height (p = 0.008) individually produced a statistically significant prediction of endobronchial diameter. The following formula was best predictive of left bronchial diameter in men: diameter (mm) = 0.032 x age (year) + 0.072 x height (cm) -2.043. Applying this formula to mean age 50 who are 158, 172, and 185 cm in height, the predicted left bronchial diameters are 11.0, 12.0, and 13.0 mm, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of epidural morphine on sedation requirements during regional anesthesia.

STUDY OBJECTIVE: To examine the effect of using analgesic doses of epidural morphine on midazolam requirements for conscious sedation during regional anesthesia. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Operating rooms at a university hospital. PATIENTS: 20 ASA physical status II and III patients aged 50 to 70 years undergoing elective peripheral vascular reconstruction with epidural anesthesia. INTERVENTIONS: At the beginning of surgery, 10 patients received 3 mg of epidural morphine, and the other 10 patients received normal saline epidurally. All patients received midazolam intravenously in bolus doses and as a continuous infusion to maintain a steady state of sedation throughout surgery. MEASUREMENTS AND MAIN RESULTS: There was no difference between the dose of midazolam required to maintain sedation in the two groups during the first 3 hours of the study. Beyond the third hour, the midazolam dose required to maintain the same level of sedation was significantly higher in the placebo group than in the epidural morphine group (p = 0.05). CONCLUSION: An analgesic dose of epidural morphine, after a latent period of 3 hours, may decrease the dose of midazolam required for sedation using regional anesthesia.

The resting volume and compliance characteristics of the bronchial cuff of left polyvinyl chloride double-lumen endobronchial tubes.

The resting volume of a low-pressure, high-volume cuff is an important factor that determines the cuff compliance, because it is the maximum volume that maintains the low-pressure characteristics of the cuff. Modern polyvinyl chloride (PVC) double-lumen tubes (DLT) are designed with a low-pressure bronchial cuff to minimize the risk of bronchial damage. Maintenance of the low-pressure characteristics of this cuff, however, requires knowledge of how its resting volume and compliance vary between different DLT sizes and brands, and how the compliance changes when the cuff is inflated inside different-sized bronchi. We, therefore, measured the bronchial cuff pressure-volume relationship for each of the adult sizes, 35 Fr, 37 Fr, 39 Fr, and 41 Fr, of the Mallinckrodt, Sheridan, Rusch, and Portex left DLTs. The compliance of each cuff was characterized by: 1) the cuff resting volume, defined as the smallest cuff volume beyond which a 0.5-mL increase in volume resulted in more than 10 mm Hg increase in cuff pressure; and 2) the cuff pressure at 3-mL volume. Measurements were repeated for sizes 35 Fr and 41 Fr left Mallinckrodt DLTs with the bronchial cuff lying inside two canine left main-stem bronchi measuring 11 mm and 13 mm in diameter. The bronchial cuff resting volume ranged from 1.5 to 5.0 mL in different sizes and brands of DLTs, which could be explained by differences in cuff size between different manufacturers and between different DLT sizes of the same manufacturer.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of three techniques to inflate the bronchial cuff of left polyvinylchloride double-lumen tubes.

Correct inflation of the cuff of any breathing tube is important; overinflation can damage the mucosa of the tracheobronchial tree and underinflation will cause a leak. Three different techniques to determine cuff seal/leak during inflation of the bronchial cuff of left double-lumen endobronchial tubes (DLT) were each evaluated in 10 patients. DLT size was chosen from a formula based on the patient's height and sex. In the first technique, designated the positive pressure technique of bronchial cuff inflation (PPT), the bronchial side of the DLT is pressurized during connection of the tracheal side to a beaker of water. Air bubbles will appear in the beaker in the absence of bronchial seal. The second technique, designated the CO2 analysis technique of bronchial cuff inflation (CAT), is based on analysis of CO2 content of gas sampled from the tracheal side of the DLT during ventilation of its bronchial side. When the bronchus is sealed, the normal CO2 waveform changes to a flat line. In the third technique, designated the negative pressure technique of bronchial cuff inflation (NPT), suction is applied to the tracheal side of the DLT. The absence of bronchial seal will result in collapse of the reservoir bag within a breathing system connected to the bronchial side of the tube. The bronchial sealing volumes were 1.1 +/- 0.9 mL, 0.9 +/- 0.7 mL, and 0.3 +/- 0.4 mL (mean +/- SD) when measured with the PPT, CAT, and NPT, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of two techniques to inflate the bronchial cuff of the Univent tube.

The Univent tube is an endotracheal tube with a movable bronchial blocker. The blocker cuff reportedly exhibits high-pressure characteristics when inflated to seal any adult bronchus. This study was aimed at measuring the cuff volume that would seal the bronchus when two different techniques of cuff inflation were used. One technique is based on creating negative pressure and the other is based on creating positive pressure within the breathing system. In addition, we directly measured the compliance characteristics of the cuff. The study was performed in eight adult patients undergoing thoracotomy. The negative pressure technique of cuff inflation (NPT) was tested by applying -150 mm Hg of pressure to the blocker lumen, causing loss of volume in the breathing system as evidenced by deflation of the reservoir bag. The blocker cuff was then inflated until the bag ceased to deflate. In the positive pressure technique of cuff inflation (PPT), the blocker lumen was connected to a beaker of water while maintaining pressure of +30 mm Hg within the breathing system. The bronchial cuff was then inflated until air bubbles ceased to appear in the beaker. Direct measurement of compliance of the blocker cuff confirmed its high-pressure characteristics. Bronchial sealing volume ranged from 3 to 5 mL when measured with the NPT and from 4 to 6 mL when measured with the PPT.(ABSTRACT TRUNCATED AT 250 WORDS)