Roger Wilson

Nonoperative Management of Tracheal Laceration During Endotracheal Intubation

Tracheal laceration is a rare but potentially devastating complication of endotracheal intubation. Traditional management of intubation-related tracheal laceration is operative. Nonoperative management of a woman noted to have a tracheal laceration during intubation is described. Criteria by which nonoperative treatment can be considered are outlined.

Value of perioperative Doppler echocardiography in patients undergoing major lung resection

BACKGROUNDnThe effects of major lung resection on right heart function have not been well established. Our goal was to evaluate these effects using serial Doppler echocardiography in the perioperative period.nnnMETHODSnIn 86 patients undergoing lobectomy (n = 47) and pneumonectomy (n = 39), we examined the effects of pulmonary resection on perioperative changes in right heart function by transthoracic echocardiography. Serial echocardiograms were performed preoperatively, on postoperative day 1, and again between postoperative days 2 and 6 (median, 3 days) to evaluate cardiovascular function and to estimate right ventricular systolic pressure by the tricuspid regurgitation jet Doppler velocity method.nnnRESULTSnRight or left atrial size, right atrial pressure, and estimated right ventricular systolic pressure did not differ between groups on the preoperative or postoperative day 1 examinations. However, on postoperative days 2 through 6 patients who underwent pneumonectomy had higher (mean +/- standard deviation) right ventricular systolic pressure values than lobectomy patients (31 +/- 15 versus 25 +/- 10 mm Hg, respectively; p < 0.05 by analysis of variance). In the subset of patients with percent predicted forced expiratory volume in 1 second less than 60% undergoing pneumonectomy (9/39), preoperative right ventricular systolic pressure was inversely correlated with percent predicted forced expiratory volume in 1 second values (r = -0.78; p < 0.04). This correlation was not significant in corresponding lobectomy patients. Postoperative right ventricular enlargement determined by echocardiography occurred with similar frequency in both groups and was associated with poor short-term prognosis in patients in whom severe respiratory failure developed.nnnCONCLUSIONSnPreoperative indices of right heart function were within the normal range in both groups. Pneumonectomy but not lobectomy was associated with mild postoperative pulmonary hypertension that was not accompanied by significant right ventricular systolic dysfunction. Postoperative echocardiography may be useful to evaluate right heart function in critically ill patients after lung resection.

The Effects of Endobronchial Cuff Inflation on Double-Lumen Endobronchial Tube Movement After Lateral Decubitus Positioning

OBJECTnThis study was designed to measure changes in tracheal and bronchial lumen distances from mainstem and secondary carina with lateral positioning, and to assess whether inflation of the endobronchial cuff before lateral positioning would further secure a double-lumen endobronchial tube (DLT) and reduce movement.nnnDESIGNnProspective study.nnnSETTINGnUniversity-affiliated cancer center.nnnPARTICIPANTSnFifty adult patients scheduled for elective thoracic surgical procedures requiring the placement of a left DLT.nnnINTERVENTIONSnPatients were sequentially assigned to either the endobronchial cuff-inflated group or the deflated group during lateral positioning. After induction of general anesthesia, a left polyvinylchloride (PVC) DLT was placed and the position confirmed. In the supine position, the distance from the tip of the tracheal lumen to main carina was measured using a fiberoptic bronchoscope (FOB) passed through the tracheal lumen, and the distance from the bronchial lumen to secondary carina was measured with the FOB passed through the bronchial lumen. The patients were then positioned laterally and a second set of measurements taken. Overall movement was determined by increases and decreases in tracheal and bronchial distances obtained by substracting supine values from lateral values.nnnMEASUREMENTS AND MAIN RESULTSnThere was significant tracheal movement in 40 of 50 patients, with a mean of 0.92 +/- 1.0 cm. This was predominantly in the upward direction, as seen in 35 of 50 patients. There was significant bronchial movement in 37 of 50 patients, with a mean of 0.92 +/- 1.15 cm. Also, predominance in the upward direction was seen in 34 of 50 patients.nnnCONCLUSIONSnDLTs move with lateral positioning, regardless of endobronchial cuff inflation. The movement is predominantly in the upward direction. Therefore, fiberoptic visualization in the supine position should be used only to confirm that the endobronchial lumen is placed on the appropriate side and the cuff is at least 1 cm inside the left mainstem bronchus. Final positioning should always be verified in the lateral position.

Peripheral κ1-opioid receptor-mediated analgesia in mice

Abstract When injected directly into the tail, U50,488H is a potent analgesic in the tailflick assay (ED 50 3.1 μg). The analgesic activity is lost if the radiant heat is focused 1 cm away from the site of injection. The κ 1 -opioid receptor antagonist nor-binaltorphimine given systemically reverses the local analgesic response of U50,488H, but the antagonist is 100-fold more potent when injected directly into the tail. Intrathecal antisense treatment with a probe targeting the mRNA encoding the κ 1 -opioid receptor blocks the local analgesic actions of U50,488H in the tail, suggesting that U50,488H is acting on dorsal ganglia neurons.

Evaluation of the tail formalin test in mice as a new model to assess local analgesic effects

Opioids are effective topical analgesics in the radiant heat tailflick assay and display synergistic interactions with a number of other classes of drugs. To determine whether these actions extend to other types of nociception, we examined the actions of topical morphine and lidocaine in a tail formalin assay in the mouse. Formalin responses in the tail were similar to those seen in the hind paw, but were limited to licking. Unlike the traditional hind paw assay, the time-course of nociceptive behavior in the tail was monophasic; lasting 40-60 min. Morphine, MK-801 and acetylsalicylic acid (ASA) were active systemically in the tail formalin assay with potencies similar to those seen in the second phase of the paw formalin test. Both morphine and lidocaine were active topically in the tail formalin assay, although their time-course of action appeared to be shorter than that of the formalin. However, morphine displayed ceiling effect not seen when it was administered systemically. Lidocaine also had a ceiling effect. When given together, the response to the combination was supra-additive, consistent with our prior studies showing synergy in the radiant heat tailflick assay. These studies validate the formalin assay in the tail and support the topical actions of opioids and other drugs in a second pain model. They also suggest supra-additive interactions between morphine and lidocaine similar to those previously seen. The tail formalin assay will be valuable in assessing the activity of topical drugs.

Impaired memory and behavioral performance with fentanyl at low plasma concentrations.

Fentanyl is commonly administered to conscious patients by continuous epidural or intravenous (IV) infusions, or by the transdermal route, which result in relatively constant, low, concentrations of the drug. Previous studies of memory and cognitive effects have not been performed at constant plasma concentrations of fentanyl. Based on simulated infusions using the pharmacokinetic modeling program IV-SIM, we administered fentanyl or placebo to nine healthy volunteers (aged 21–45 yr) by continuous IV infusion, targeting plasma concentrations of 1, 1.5, and 2.5 ng/mL in succession. A battery of memory and psychomotor tasks was administered at each plasma concentration of fentanyl, and at two points in the recovery phase while drug levels were decreasing. At increasing plasma concentrations of fentanyl, we found the following effects on memory (in comparison with placebo): a progressive decline in verbal learning (P < 0.03); decreased delayed recognition of words presented at different test times (P < 0.02); and decreased spontaneous recall of pictures shown during infusion (P < 0.03). Fentanyl at concentrations above 2.5 ng/mL caused a performance decrement of 15%-30% relative to baseline on all the psychomotor tests administered. Plasma concentrations less than 2.25 ng/mL had negligible effects on performance with the exception of the critical flicker fusion frequency, which decreased by 5 Hz at plasma concentrations between 1.5 and 2.25 ng/mL. Visual analog scale (VAS) measures of mental and physical sedation were significantly affected by fentanyl, but euphoria was not demonstrable. All subjects receiving fentanyl experienced severe nausea and four of six had one or more episodes of emesis (P < 0.03). We conclude that even though patients experiencing constant, low plasma concentrations of fentanyl appear to be awake, they could have significantly impaired memory.

Blockade of Morphine-Induced Hindlimb Myoclonic Seizures in Mice by Ketamine

Morphine administration can lead to a variety of side-effects, including myoclonus. In an animal model, high morphine doses given intrathecally elicit hindlimb myoclonic seizures which are not influenced by traditional opioid receptor antagonists, such as naloxone. Ketamine prevents this seizure-like activity in a dose-dependent manner. The response is stereoselective, with S-ketamine far more potent than R-ketamine. A competitive NMDA antagonist, NPC17742, also prevents the seizures, although less potently than ketamine. Dextromethorphan has limited activity in this model, while haloperidol and pentothal are without any effect.