Cytopathologic examination of epidural catheter for postoperative analgesia. Pathophysiology and clinical management.

AIM: The authors performed a prospective study in a series of patients undergoing combined general and epidural anaesthesia for major abdominal surgery in order to define if the epidural catheter inserted for postoperative analgesia induced in the short-term (7-8 postoperative days) any cytopathologically appreciable inflammatory response. METHODS: From April to September 2001, 20 consecutive patients undergoing combined general and epidural anaesthesia for major abdominal surgery at the National Cancer Research Institute and Villa Scassi Hospital (Genoa), were recruited after obtaining Institutional Ethics Committee approval and written consent from the patients. The standard technique for epidural anaesthesia was adopted. Preoperatively, all patients received peridurally a dose test of 3 ml of 2% lidocaine (60 mg) followed by 5 ml of ropivacaine 0.75%, and a continuous infusion of ropivacaine 0.375% (5-10 ml/h; maximal dose=20 ml) intraoperatively. As regards the therapeutic management of postoperative analgesia, patients received a continuous infusion of ropivacaine 0.2% for at least 48 hours and supplemental bolus (2 mg/die) of morphine hydrochloride. The epidural catheter was always removed between the 7th and 8th postoperative day, and it was examined by the pathologist according to the Thin Prep 2000 procedure. RESULTS: The cytopathologic examination of the tip of the epidural catheter gave the following findings: amorphous material without cells (n=10); rare granulocytes and histiocytes (n=6); stromal cells (n=3), and rare lymphocytes (n=1). CONCLUSION: We were unable to detect any cytopathologically appreciable inflammatory response at the tip of the epidural catheter which could have suggested the occurrence of inflammation in the epidural tissues. Given the positive results of prophylactic epidural administration of small doses of corticosteroids in the reduction of postepidural anaesthesia back pain and their direct membrane action on nociceptive C-fibers, this kind of backache seems to be related to the stimulations of such nociceptors more than to a catheter-related inflammatory response of epidural tissues with possible evolution in peridural fibrosis, as reported following surgical intervention for lumbosacral disease.

Do pipecuronium and rocuronium affect human bronchial smooth muscle?

BACKGROUND: Muscle relaxants affect nicotinic and muscarinic receptors. Interaction of muscle relaxants with muscarinic receptors of human airways has been studied incompletely. METHODS: The effects of pipecuronium bromide (long-acting, nondepolarizing) and rocuronium bromide (intermediate-acting, nondepolarizing) on prejunctional and postjunctional muscarinic receptors were studied in 96 isolated human bronchial rings from 12 patients. Contractile isometric responses to electric field stimulation of pilocarpine-stimulated and nonstimulated M2 muscarinic receptors were compared before and after incubation with the two muscle relaxants. The effect on postjunctional muscarinic receptors was studied by comparing acetylcholine concentration-response curves before and after incubation with the two muscle relaxants. RESULTS: Pipecuronium bromide, but not rocuronium bromide, inhibited pilocarpine-stimulated prejunctional M2 muscarinic receptors. Neither pipecuronium bromide nor rocuronium bromide had significant inhibitory effects on nonstimulated M2 muscarinic receptors and on postjunctional M3 muscarinic receptors. CONCLUSIONS: The inhibitory effect of pipecuronium bromide on pilocarpine-stimulated prejunctional M2 muscarinic receptors occurred at clinical concentrations.

Inhibition of airway constriction by opioids is different down the isolated bovine airway.

BACKGROUND: Opioid agonists attenuate in isolated airways contractile responses to electrical field stimulation (EFS), and this attenuation is mediated by opioid receptors. Differences exist in the density of muscarinic and beta-adrenergic receptors between large and small airways. The authors hypothesized that the density of opioid receptors may also be different down the airway. METHODS: The effects of three selective opioid agonists (mu, kappa, delta) on EFS-induced contractions were compared between isolated bovine sublobar (4- or 5-mm inner diameter) and segmental (2- or 3-mm inner diameter) bronchial rings and between trachealis strips and bronchial rings. RESULTS: D-Ala2-N-MePhe4-Gly-ol5 enkephalin (DAMGO; 10(-5) M), a mu-opioid agonist, attenuated EFS-induced contractions of isolated sublobar and segmental bronchial rings at low stimulating frequencies of 0.5 Hz (P < 0.001), 2 Hz (P < 0.001), and 8 Hz (P < 0.001), but not at 32 Hz (P = 0.071). The inhibitory effect of DAMGO was antagonized by naloxone (10(-5) M) (P = 0.025). The selective kappa-opioid agonist U-50488 H (10(-5) m) attenuated EFS-induced contractions at 32 Hz (P = 0.008) and 8 Hz (P = 0.045), but not at 2-Hz (P = 0.893) or 0.5-Hz (P = 0.145) contractions. The inhibitory effects of 10(-5) M U-50488 H were not antagonized by the highly selective kappa-antagonist 2,2'-[1,1'-biphenyl] 4,4'-diyl-bis [2-hydroxy-4,4-dimethyl]-morpholinium (nor-BNI; 10(-5) M; P = 0.216) or naloxone (10[-5]) M; P = 0.065). The selective delta-agonist D-penicillamine2-D-penicillamine5-enkephalin (DPDPE) (10(-5) M) had no inhibitory effects (P = 0.256). The inhibitory effects of the selective mu-opioid agonist DAMGO were smaller (P < 0.001) and those of U-50488 H larger (P < 0.001) in trachealis strips compared with bronchial rings. CONCLUSIONS: The attenuation of EFS-induced contractions by DAMGO in isolated bovine bronchi was mediated by prejunctional opioid receptors. In contrast, the inhibitory effect of U-50488 H was probably not mediated by opioid receptors in the bronchi.

Opioid agonists modulate release of neurotransmitters in bovine trachealis muscle.

BACKGROUND: Stimulation of opioid receptors in the airways can modulate cholinergic neurotransmission and thereby reduce bronchoconstriction. This protecting effect of opioids against bronchoconstriction may be of clinical interest. Inhalation of opioids as a method of analgesia is likely to result in an opioid concentration at airway receptors sufficient to protect against bronchoconstriction; the concentration may be insufficient when opioids are administered by conventional techniques. In addition, new selective opioids may be developed that could more selectively protect the airways against bronchoconstriction. METHODS: The effect of three selective opioid agonists on the contractile response to electric field stimulation (EFS) was studied in isolated muscle strips from four regions of the bovine trachea (upper, or laryngeal; upper middle; lower middle; lower, or carinal). RESULTS: The selective kappa agonist trans-3,4-dichloro-N-methyl-N-(2-1-pyrrolidinyl) cyclohexyl benzene acetamide (U-50488 H) and the selective mu-opioid agonist D-Ala2-N-MePhe4-Gly-ol5-enkephalin (DAMGO) reduced significantly (P < 0.001 and P < 0.001, respectively) the contractile response to EFS. The attenuation of the contractile response by U-50488 H was concentration-dependent (P < 0.0001) and tended to be larger at low stimulating frequencies (P = 0.055). The attenuation of the contractile response by DAMGO was frequency-dependent (P < 0.01). The selective delta-opioid agonist D-penicillamine2-D-penicillamine5-enkephalin had no significant effect on the contractile response to EFS (P = 0.71). There were no significant differences among the four regions of the trachea in their responses to the selective opioid agonists U-50488 H (P = 0.50) and DAMGO (P = 0.44). Neither U-50488 H nor DAMGO altered the contractile response to acetylcholine P > 0.11, P > 0.21, respectively), suggesting that the opioid agonists have a prejunctional effect. The attenuation of the contractile response to EFS by U-50488 H was partially but significantly antagonized by 10(-5) M naloxone (P < 0.01) and by 10(-5) and 10(-6) M of the selective kappa-opioid antagonist 2,2'-[1,1'-biphenyl] 4,4'-diyl- bis [2-hydroxy-4,4-dimethyl-morpholinium] (P < 0.05). Naloxone (10(-5) M) abolished the inhibitory effect of DAMGO, suggesting that opioid receptors are involved in the attenuation of the contractile response to EFS afforded by DAMGO and U-50488 H. CONCLUSIONS: We conclude that prejunctional kappa- and mu-opioid receptors attenuate the contractile response of isolated bovine trachealis muscle to EFS by inhibiting cholinergic neurotransmission. This effect is uniform throughout the trachealis muscle. delta-Opioid receptors are apparently not present in the bovine trachealis muscle. Caution must be used in extrapolating these results to the intact human. In this study little or no inhibitory effect of the opioids was observed at concentrations expected at airway receptor sites when administered by conventional techniques. However, the effect may be large enough to protect against bronchoconstriction when nebulized opioids are administered by inhalation.

[Perioperative blood gas analysis in 100 patients in spontaneous respiration treated with ND-YAG laser for endoluminal tracheo-bronchial neoplasms]. / Valutazioni emogasanalitiche perioperatorie in 100 pazienti in ventilazione spontanea trattati con ND-YAG laser per neoplasie tracheo-bronchiali endoluminali.

OBJECTIVE: To determine the reliability on spontaneous ventilation of small continuously associated doses of ketamine and propofol during yag-laser therapy for upper airways neoplastic obstructions. DESIGN: Prospective description of blood gas analysis variation throughout the intervention and in the early postoperative period. SETTING: Operating theatre and postoperative Intensive Care Unit of the National Institute for Cancer Research. PATIENTS: A hundred consecutive cancer patients referred to our Institution for upper airways tumoral progressive obstruction. INTERVENTION: Yag-laser firing. MEASUREMENTS AND MAIN RESULTS: Pre-intra and postoperative blood gas analysis, BP, HR, Sat O2 have been registered every 10'. Mean intraoperative pCO2 rose to 47.3 mmHg (30-60), but within 2 to 3.20 hrs returned close to preoperative value (38.3 mmHg) allowing early patient discharge. CONCLUSIONS: The i.v. association of 0.7-1.0 mg/kg Ketamine and 1 mg/kg propofol, followed by 5 micrograms/kg/h and 3 mg/kg/h respectively, turned out to be satisfactory for both patients and anaesthetists in terms of anaesthesia and spontaneous breathing maintenance during yag-laser firing for obstructive upper airways cancer patients.

The transverse rectus abdominis musculocutaneous flap for breast reconstruction in obese patients.

Transverse rectus abdominis musculocutaneous (TRAM) flap breast reconstruction has often been considered contra-indicated in obese women. The morphological characteristics peculiar to this population, however, make obese women ideal candidates for this procedure because the reconstructed breast must often match a large ptotic contralateral breast. About one-third of our postmastectomy patients are corpulent, middle-aged women with "Mediterranean" body structures. Thirty-four obese women underwent TRAM flap breast reconstruction from 1985 to 1988. According to the Body Mass Index, 23 women had type II obesity and 11 had type III obesity. The preoperative and postoperative management and the surgical procedure were adapted to this particular group of women. The complication rate in this series of women was superior to that of a nonobese population; however, no severe complications were observed. The majority of women were extremely satisfied with aesthetic results; the surgeons also judged the final cosmetic outcome to be very favorable and, indeed, superior to that obtainable with simpler methods. Obesity uncomplicated by other risk factors does not represent an absolute contraindication to TRAM flap procedure.