Abdel Raouf El-Ganzouri

Preoperative airway assessment: Predictive value of a multivariate risk index

Using readily available and objective airway risk criteria, a multivariate model for stratifying risk of difficult endotracheal intubation was developed and its accuracy compared to currently applied clinical methods.We studied 10,507 consecutive patients who were prospectively assessed prior to general anesthesia with respect to mouth opening, thyromental distance, oropharyngeal (Mallampati) classification, neck movement, ability to prognath, body weight, and history of difficult tracheal intubation. After induction of anesthesia, the laryngeal view during rigid laryngoscopy was graded and the ability of experienced anesthesia personnel to ventilate via a mask was determined. Poor intubating conditions (laryngoscopy Grade IV) and inability to achieve adequate mask ventilation were identified in 107 (1%) and 8 (0.07%) cases, respectively. Logistic regression identified all seven criteria as independent predictors of difficulty with laryngoscopic visualization. A composite airway risk index (derived from nominalized odds ratios calculated from the multivariate model) as well a simplified (0 = low, 1 = medium, 2 = high) risk weighting exhibited higher positive predictive value for laryngoscopy Grade IV at scores with similar sensitivity to Mallampati class III, as well as higher sensitivity at scores with similar positive predictive value. Compared to Mallampati class I fewer false-negative predictions were observed at a risk index value of 0. We conclude that improved risk stratification for difficulty with visualization during rigid laryngoscopy (Grade IV) can be obtained by use of a simplified preoperative multivariate airway risk index, with better accuracy compared to oropharyngeal (Mallampati) classification at both low- and high-risk levels. (Anesth Analg 1996;82:1197-204)

Monoamine oxidase inhibitors: Should they be discontinued preoperatively?

Adverse cardiovascular responses to anesthesia during either electroconvulsive therapy (ECT) or elective surgical procedures were evaluated in 27 patients maintained on chronic (3 months--3 yr) monoamine oxidase inhibitor (MAOI) therapy. Changes in blood pressure and heart rate in study patients (n = 22 ECTs in 13 patients) undergoing ECT were not significantly different from those observed in patients having ECT without prior treatment with MAOIs (n = 45 ECTs in 45 patients). In both groups, blood pressure and heart rate increased significantly after ECT, but returned to baseline levels within 15 min. No complications attributable to MAOIs were observed in study patients (n = 14) undergoing elective surgical procedures. We conclude that discontinuing chronic MAOI therapy prior to anesthesia and surgery is not necessary.

Sufentanil-midazolam anesthesia for coronary artery surgery

The combination of benzodiazepines and high-dose narcotics has been reported to produce hypotension in patients undergoing coronary artery surgery. This study was performed to evaluate the cardiovascular effects of lower doses of the narcotic sufentanil administered with the benzodiazepine midazolam. Thirty adult patients with good ventricular function undergoing elective coronary revascularization received sufentanil, 2.5 micrograms/kg, and midazolam, 0.1 mg/kg, followed by infusions of sufentanil, 0.7 to 1.5 micrograms/kg/h, and midazolam, 0.07 to 0.15 mg/kg/h. Overall, stable hemodynamics were achieved before and after cardiopulmonary bypass (CPB). Patients who were not receiving preoperative beta-adrenergic blockade (n = 15) had increases from baseline heart rate and rate-pressure product after sternotomy, during aortic dissection, and after CPB that were not clinically significant. Five patients developed hypertension (increases greater than 20% over the baseline value), which was controlled with additional sufentanil or a vasodilator. Hypertension requiring vasodilator therapy did not occur in patients taking beta-adrenergic blockers. Blood pressure decreases exceeding 20% of the baseline value did not occur. Two of 15 patients receiving beta-blockers, versus 3 of 15 not receiving beta-blockers, developed ischemic electrocardiographic changes before CPB (NS); one of these patients without beta-blockade had a postoperative myocardial infarction. The results of this study show that the infusion of low doses of sufentanil with midazolam provides a hemodynamically safe and stable anesthetic for coronary artery surgery and avoids the hypotension seen when a high-dose narcotic is combined with a benzodiazepine.

One-Lung High-Frequency Positive Pressure Ventilation for Sleeve Pneumonectomy: An Alternative Technique

High-frequency positive pressure ventilation (HFPPV) was originally used in experimental animal studies in 1971 by Jonzon et a1 (I),. and the technique was introduced into clinical anesthesia by Heijman et a1 (2) the following year. HFPPV incorporates the use of a small tidal volume approaching the volume of dead space at a frequency of 1 Hz or more. HFPPV provides adequate ventilation and oxygenation mainly by the generation of eddy flow in the airways, leading to an improvement in the intrapulmonary gas mixture and distribution as well as facilitating gas diffusion. The airway pressure during HFPPV is continuously positive, with low mean and peak pressures, whereas the intrapleural pressure is continuously subatmospheric with minimal effect on the pulmonary and systemic circulation (3).

High-frequency positive-pressure ventilation for tracheal reconstruction supported by tracheal T-tube.

High-frequency positive-pressure ventilation (HFPPV) was first described by Oberg and Sjostrand (I), who demonstrated in animals that ventilation and oxygenation could be adequately maintained with much lower tidal volumes and higher respiratory rates than conventionally used. This method of ventilation was studied in humans by Jonzon et a1 (2) and was first reported during clinical anesthesia and surgery by Heijman et a1 in 1972 (3). HFPPV is one of two types of high-frequency ventilation; the other is high-frequency oscillation. They differ in the tidal volumes and respiratory rates used. In HFPPV, tidal volumes that approach the anatomic dead space (50 to 250 ml) are delivered at rates of 1 to 10 Hz (60 to 600 breaths/min); alveolar ventilation with this technique is thought to be accomplished by a combination of convection and improved gas diffusion. In high-frequency oscillation, lower tidal volumes (5 to 50 ml) are delivered at rates of 10 to 100 Hz (600 to 6000 breaths/min); alveolar ventilation during high-frequency oscillation is thought to be accomplished by acceleration of gas diffusion and collateral intra-alveolar ventilation (4-7). The high velocity of the small tidal volumes deliv-

High-dose sufentanil: four cases of sudden hypotension on induction.

Sufentanil, an N,-substituted derivative of the synthetic narcotic fentanyl, has recently been released for clinical usage. High-dose opiate anesthesia has been a well-accepted technique for cardiac surgery since Lowenstein et al. (1) published their work using morphine, 1-3 mgkg. Fentanyl in dosages of 50-100 pgkg releases little histamine and provides a hemodynamically acceptable anesthetic. Sufentanil, 15-25 pglkg, has been said not only to provide as stable an induction as fentanyl, but also potentially to add further protection from intraoperative hypertension and tachycardia, and to produce less postoperative respiratory depression (2). The following clinical report describes four patients in whom sudden hypotension developed on induction of anesthesia with sufentanil ranging in dose from 8.4 pglkg to 22.7 pglkg. Three patients were having cardiac surgery: coronary artery bypass graft (CABG) in one, mitral valve replacement (MVR) in one, and combined MVR and CABG in the third. The fourth patient was scheduled for resection of an abdominal aortic aneurysm (AAA). At this time ten cases of highdose sufentanil anesthesia have been carried out at this institution, including the four reported here.

Air-Q laryngeal airway for rescue and tracheal intubation ☆ ☆☆ ★ ★★ ☆☆☆

We report the successful use of the Air-Q laryngeal airway (Air-Q LA) as a ventilatory device and a conduit for tracheal intubation to rescue the airway in a patient with difficult airway and tracheal stenosis. This is the first case report of the device to secure the airway after two episodes of hypoxemia in the operating room and intensive care unit. Consent for submission of this case report was obtained from our institutions human studies institutional review board given that the patient died a few months after his discharge from the hospital before his personal consent could be obtained and before preparation of this report. All personal identifiers that could lead to his identification have been removed from this report. A 59-year-old man was scheduled for a flexible and rigid bronchoscopy with possible laser excision of tracheal stenosis. He had a history of hypertension, atrial fibrillation, and diabetes. Assessment of airway revealed a thyromental distance of 6.5 cm, Mallampati class II, and body weight of 110 kg. He had hoarseness and audible inspiratory/expiratory stridor with Spo2 90% breathing room air. After induction and muscle relaxation, tracheal intubation and flexible bronchoscopy were achieved without incident. The patient was then extubated and a rigid bronchoscopy was attempted but failed with Spo2 dropping to 92%; rocuronium 60 mg was given, and reintubation was accomplished with a 7.5-mm endotracheal tube. A second rigid bronchoscopy attempt failed, with Spo2 dropping to 63%. Subsequent direct laryngoscopy revealed a bloody hypopharynx. A size 4.5 Air-Q LA was placed successfully and confirmed with capnography, and Spo2 returned to 100%. The airway was suctioned through the Air-Q LA device, and the airway was secured using a fiberoptic bronchoscope to place an endotracheal tube of 7.5-mm internal diameter. The case was canceled because of edema of the upper airway from multiple attempts with rigid bronchoscopy. The patient was transported to the surgical intensive care unit (SICU). During day 2 of his SICU stay, he accidentally self-extubated and Spo2 dropped to 20% prompting a code blue call. A size 4.5 Air-Q LA was successfully placed by the anesthesia resident on call and Spo2 rose to 100%. The airway was then secured after suction of bloody secretions and visualization of edematous vocal cords with a fiberoptic bronchoscope and proper placement of an endotracheal tube of 7.5-mm internal diameter, confirmed by capnography. During the short period of hypoxemia, the patients blood pressure, heart rate, and electrocardiogram had remained stable. On the sixth day of SICU admission, he underwent surgical tracheostomy and laser excision of a stenotic tracheal lesion, returned to the SICU, was weaned off mechanical ventilation, and discharged 2 weeks later to a rehabilitation center with stable ventilatory capabilities. This case demonstrates successful use of the Air-Q LA in the emergency loss of airway scenario as a ventilatory device and as a conduit for endotracheal intubation when fiberoptic bronchoscopy alone may be difficult and hazardous. This case suggests the need for further evaluation of the impact of the Air-Q LA on outcomes when used as a rescue device and conduit for tracheal intubation in patient with disease activity.

Complications of Rigid Laryngoscopy and Tracheal Intubation

To the Editor: We read with great interest the article of Lee JJ et al. that describes two complications of tracheal intubation in a neonate. We believe, however, that these two complications could have been avoided if the following precautions and techniques were used. (1) Tracheal intubation was achieved after three esophageal intubations. It was not mentioned if the esophageal intubation was done because of difficult airway or involved an endoscopist not experienced in neonatal intubation. If the case was difficult airway and the glottis was not seen, a supraglottic airway such as an Air-QTM #1.0 (Clearwater, FL) could have been immediately inserted to provide ventilation. If an endotracheal intubation is mandatory, a fiberoptic-guided tracheal intubation through the Air-QTM can be performed. (2) Proper placement of the endotracheal tube (ETT) to 8 cm distance at the lips could have avoided the right endobronchial intubation if the ETT was pulled to 8 cm at the lips and not left at 11 cm while starting positive pressure ventilation. (3) Proper placement of the ETT can be confirmed by: bilateral breath sounds, capnogrpahy, and insertion of a lubricated ultra-thin fiberoptic scope through the ETT (Olympus LF-P [Center Valley, PA] with a 2.2 mm external diameter) and confirming placement of the ETT (1.0 –1.5 cm) above the carina in this case. If these precautions were followed, the endobronchial intubation and unnecessary surgery for gastric perforation from esophageal intubation could have been avoided. The authors have currently concluded that specialized training and experience are needed for neonatal airway management. However, use of a supraglottic airway as described above improves the likelihood of successful airway management by less experienced clinicians.

Continuous Epidural Infusion for Analgesia After Major Abdominal Operations: A Randomized, Prospective, Double-Blind Study

We performed a prospective, randomized, double-blind study of continuous epidural analgesia for 72 hours after major abdominal procedures. Patients were randomly assigned to one of five treatment groups: epidural morphine, epidural bupivacaine, a combination of morphine and bupivacaine, epidural saline solution, and no epidural catheter. All patients received supplemental morphine sulfate or meperidine hydrochloride, intramuscularly or intravenously, as needed. Epidural infusion was begun at 2 to 4 ml/hr, depending on age and height, with two increments of 1 ml/hr allowed if pain relief was insufficient. All pain management decisions were made by nurses, who also monitored epidural function. Performance was measured four ways: pain as measured at regular intervals in the 72-hour period with a visual analog, pain as measured after 72 hours with the McGill Pain Questionnaire, amount of supplemental narcotics needed, and recovery of respiratory function and ambulation as percent of preoperative levels. The group that received the combination of morphine and bupivacaine did best on all measures; in most instances the difference between the results seen with the combination regimen and those seen with saline solution or no catheter were significant at the 0.05 level. With the exception of pruritus, complications were evenly distributed among all treatment groups, including noncatheterized controls. We conclude that epidural analgesia with the combination of morphine and bupivacaine is safe, is easily managed, and gives pain relief superior to that provided by traditional, systemic administration of narcotics.