Jeffrey A. Katz

Adverse Reactions to Isosulfan Blue During Selective Sentinel Lymph Node Dissection in Melanoma

Background: Selective sentinel lymph node (SLN) dissection can spare about 80% of patients with primary melanoma from radical lymph node dissection. This procedure identifies the SLN either visually by injecting isosulfan blue dye around the primary melanoma site or by handheld gamma probe after radiocolloid injection.Methods: During selective SLN mapping, 1 to 5 ml of isosulfan blue was injected intradermally around the primary melanoma. From November 1993, to August 1998, 406 patients underwent intraoperative lymphatic mapping with the use of both isosulfan blue and radiocolloid injection. Three cases of selective SLN dissection, in which adverse reactions to isosulfan blue occurred, were reviewed.Results: We report three cases of anaphylaxis after intradermal injection with isosulfan blue of 406 patients who underwent intraoperative lymphatic mapping by using the procedure as described above. The three cases we report vary in severity from treatable hypotension with urticaria and erythema to severe cardiovascular collapse with or without bronchospasm or urticaria.Conclusions: In our series, the incidence of anaphylaxis to isosulfan blue was approximately 1%. Anaphylaxis can be fatal if not recognized and treated rapidly. Operating room personnel who participate in intraoperative lymphatic mapping where isosulfan blue is used must be aware of the potential consequences and be prepared to treat anaphylaxis.

Inspiratory work with and without continuous positive airway pressure in patients with acute respiratory failure.

To compare the effects of continuous positive airway pressure (CPAP) with those of ambient end-expiratory pressure (T-tube) on lung mechanics and blood gas exchange, transpulmonary pressure (Ptp), tidal volume (VT), respiratory frequency, and arterial oxygen and carbon dioxide tensions were measured in 16 spontaneously breathing patients recovering from acute respiratory failure. These variables were measured during breathing through a T-tube; with 18, 12, and 6 cm H2O CPAP; and again during breathing through a T-tube. During all levels of CPAP, mean effective lung compliance (Ceff) was higher and mean total pulmonary power during inspiration lower than during breathing through a T-tube before CPAP (P < 0.05). The data obtained at the level of CPAP producing maximum Ceff (optimum CPAP) were grouped and compared with values obtained during breathing through a T-tube. Mean total pulmonary power of inspiratory muscles during breathing through a T-tube before CPAP (0.7 ± 0.14 kg.m.min-1) decreased during optimum CPAP (0.44 ± 0.07 kg.m.min-1) and increased during breathing through a T-tube after CPAP (0.63 ± 0.12 kg.m.min-1). Mean VT was higher (557 ± 63 ml vs. 474 ± 47 ml) and frequency lower (17.5 ± 1.6 breaths/min vs. 22.5 ± 2.5 breaths/min) during optimum CPAP than during breathing through a T-tube before CPAP, and inspiratory time was significantly longer. Mean minute ventilation was also lower during optimum CPAP (8.7 ± 0.6 1/min) than during breathing through a T-tube (9.6 ± 0.8 1/min); Paco2 did not change significantly. Mean alveolar-to-arterial oxygen pressure difference decreased significantly during optimum CPAP. The authors conclude that CPAP, when adjusted to the appropriate levels, improves lung mechanics in patients recovering from acute respiratory failure. Continuous positive airway pressure reduces total pulmonary power during inspiration and at the same time improves oxygen and carbon dioxide exchange. In these respects, it is preferable to breathing through a T-tube without CPAP.

Time Course and Mechanisms of Lung-volume Increase with PEEP in Acute Pulmonary Failure

To determine the effects of a step change in end-expiratory pressure on functional residual capacity (FRC) and lung-thorax compliance (CLT), 10 cm H2O positive end-expiratory pressure (PEEP) was applied in eight patients who needed mechanical ventilation for acute pulmonary failure. Of the total change in FRC, 66 ± 5.3 per cent (mean ± SEM) was complete within the next breath, and 90 per cent change was achieved in 4.6 ± 1.4 breaths (24 ± 6.4 sec). There was no statistically significant difference between times to 90 per cent FRC change with application and with removal of PEEP. In another 13 patients, PEEP was increased in 5 cm H2O steps from 3 to 18 cm H2O. Mean FRC at 3 cm H2O PEEP was 1.51 ± 0.20 1 (55 ± 7.0 per cent predicted supine value). Mean CLT did not change significantly until 18 cm H2O PEEP was reached, at which point it decreased (P < 0.005). The static compliance derived from change in FRC (ΔFRC/ΔPEEP) increased with increments of PEEP (P < 0.05) compared with the initial level. At PEEP levels of 8 and 13 cm H2O, mean FRC was larger than would be predicted from mean CLT (P < 0.005), but it was not significantly different at 3 cm H2O PEEP. The lung component accounted for 62 ± 3.7 per cent of the lung-thorax compliance difference. These data define a time-dependent increase in lung volume that resembles pressure-volume hysteresis in normal man. Possible mechanisms include surface tension changes, recruitment of nonventilated lung, and stress relaxation of lung and chest wall. This study may explain the greater efficiency of PEEP compared with large tidal-volume ventilation in increasing PaO2 in patients with acute pulmonary failure.

Recall of Surgery for Major Trauma

&NA; Major traumatic injury frequently causes hemodynamic instability that necessitates reducing the usual dose of anesthetic given for surgery. Nevertheless, a lower dose may be sufficient to provide anesthesia because of conditions present in trauma victims that are known to reduce anesthetic requirement (hypotension, hypothermia, and acute alcohol intoxication). To determine the incidence and patient perception of recall of surgery, 51 patients were interviewed after surgery for major trauma. Patients were assigned to one of two groups. Thirty‐seven patients were given an anesthetic for endotracheal intubation and had continuous or almost continuous anesthesia during surgery. Of the four who recalled surgery (11%), two considered this awareness their worst hospital experience. Fourteen other patients, who were more severely injured, were not given an anesthetic for endotracheal intubation and/or for 20 or more consecutive minutes during surgery. Of the six patients in this group who recalled surgery (43%), two considered this awareness their worst hospital experience. No condition known to reduce anesthetic requirement did so reliably enough that recall of surgery did not occur when the anesthetic dose had to be reduced because of major trauma. The authors conclude that the incidence of recall of surgery in victims of major trauma is considerable, and that reducing the dose of anesthetic increases this incidence, despite the presence of conditions known to reduce anesthetic requirement.

Nausea and vomiting following thyroid and parathyroid surgery

STUDY OBJECTIVES To determine the incidence of postoperative nausea and vomiting (PONV) following thyroid and parathyroid surgery. To determine whether PONV is reduced when propofol is used for maintenance of anesthesia as compared to isoflurane and to evaluate the costs and resource consumption associated with these two anesthetic regimens. DESIGN Randomized, prospective study. SETTING University-affiliated hospital--a referral center for endocrinologic surgery. PATIENTS 118 ASA physical status I and II patients, aged 18 years and older, undergoing elective thyroid or parathyroid surgery. INTERVENTIONS Patients received either isoflurane (0.5 to 1.3% end-tidal) or propofol (50 to 200 micrograms/kg/min) for maintenance of anesthesia. All patients received propofol for induction of anesthesia, succinylcholine or vecuronium, nitrous oxide, and fentanyl. Prophylactic antiemetics were not administered. Postoperative pain was treated with ketorolac, fentanyl, or acetaminophen. MEASUREMENTS AND MAIN RESULTS Signs and symptoms of nausea and vomiting were graded on a four point scale as 1 = no nausea; 2 = mild nausea; 3 = severe nausea; 4 = retching and/or vomiting. Grades 3 and 4 were grouped together as PONV. The combined incidence of PONV was 54% over the 24-hour postoperative evaluation period. PONV was significantly more common in patients receiving isoflurane than propofol for maintenance of anesthesia (64% vs. 44%). In women (n = 87), the incidence of PONV was significantly greater in those patients who received isoflurane than those who received propofol for maintenance (71% vs. 42%). However, in men (n = 31), there was no significant difference in PONV between anesthetic regimens (47% with isoflurane vs. 50% with propofol). There were no differences in the duration of stay in the postanesthesia care unit, time to discharge from the hospital, or local wound complications (hematomas) between groups. The use of propofol for maintenance of anesthesia was associated with an additional cost, relative to the isoflurane group, of

Pharmacodynamics and pharmacokinetics of epidural ropivacaine in humans

54.26 per patient. CONCLUSION Patients undergoing thyroid or parathyroid surgery are at high risk for the development of PONV. Propofol for maintenance of anesthesia, although more expensive than isoflurane, reduces the rate of PONV in women.

Lung volumes, mechanics, and oxygenation during spontaneous positive-pressure ventilation: the advantage of CPAP over EPAP.

The purpose of this study was to characterize the pharmacodynamics and pharmacokinetics of three concentrations of the new long-acting amide local anesthetic, ropivacaine, given epidurally in 15 physical status ASA I or II patients for elective, lower-extremity orthopedic procedures using a nonrandomized open-label design. Three groups of five patients each received either 0.57%, 0.75%, or 1.0% ropivacaine. Upper and lower levels of analgesia to pinprick were determined at frequent intervals until normal sensation had completely returned. Motor blockade ums assessed by use of a modified Bromage scale after each determination of level of analgesia. Fifteen venous blood samples were collected over 12 h after ropivacaine injection. Pharmacokinetic parameters were derived using serum concentration-time data. No significant differences were found between the three groups in terms of onset or recovery of motor and sensory blockade. Median maximum thoracic levels of analgesia achieved were 8, 6, and 5 for the 0.5%, 0.75%, and 1.0% groups, respectively, and occurred at 29 ± 11, 37 ± 23, and 30 ± 9 min. Respective times to two-segment regression were 2.8 ± 1.0, 3.0 ± 0.5, and 2.9 ± 0.6 h. Total durations of sensory blockade were 5.4 ± 0.7, 6.5 ± 0.4, and 6.8 ± 0.8 h, respectively. No statistically significant differences were noted between the three groups in term of clearance (CL). The mean residence time (MRT) was significantly longer for the 0.5% group when compared with the 1% group. The peak concentration (Cmax) for the 0.5% group was found to be significantly lower than for either the 0.75% or 1% groups. Mean (± SD) values of the pharmacokinetic parmeters for the 0.5%, 0.75%, and 1.0% groups were, respectively, MRT: 9.9 ± 3.6, 7.5 ± 2.6, and 4.5 ± 0.8 h; CL: 0.35 ± 0.21, 0.34 ± 0.24, and 0.52 ± 0.11 L·kg−1·h−1; Cmax: 0.53 ± 0.19, 1.07 ± 0.57, and 1.53 ± 0.60 μg/mL; and tmax: 1.6 ± 1.4, 0.66 ± 0.19, and 0.65 ± 0.16 h. Pharmacokinetic and pharmacodynamic characteristics of epidural ropivacaine are similar to those of epidural bupivacaine in humans.

Complete airway obstruction during arthroscopic shoulder surgery

To determine if continuous positive airway pressure (CPAP) or expiratory positive airway pressure (EPAP) is superior for achieving or maintaining effective lung volume in spontaneously breathing critically in patients in acute respiratory failure, the authors measured functional residual capacity (FRC), airway and esophageal pressures, and arterial oxygen tensions when CPAP and EPAP were 5 and 10 cm H2O. Arterial oxygenation, FRC, and transpulmonary pressure at end-expiration were greatest when CPAP was 10 cm H2O. Lung compliance did not change. The authors conclude that CPAP at 10 cm H2O is the more effective technique, either because it allows relaxation of chest wall musculature on expiration, or because EPAP at 10 cm H2O increases chestwall muscle tone.

Mivacurium-induced neuromuscular blockade following single bolus doses and with continuous infusion during either balanced or enflurane anesthesia

A rthroscopic surgery of the shoulder has become common and routine. The popularity of the arthroscopic approach derives from significant advantages compared to open-shoulder surgical techniques. Decreased length of hospitalization (most procedures are done on an ambulatory surgery basis), lower infection rate, and reduced incisional pain combine to make arthroscopic procedures safe and effective (1). Anesthetic considerations specific to arthroscopic procedures generally are limited to patient positioning and choice of regional versus general anesthesia. Arthroscopy per se poses few anesthetic challenges. However, to alert clinicians to a potential catastrophic intraoperative emergency, we report a case in which extraarticular dissection of arthroscopic irrigation solution resulted in the abrupt onset of complete airway obstruction in an awake patient undergoing shoulder arthroscopy with interscalene block anesthesia.

Pressure and flow limitations of anesthesia ventilators.

Mivacurium chloride (BW B1090U) was administered to 72 patients during their elective surgery. The eight groups (nine subjects per cell) in the 2 x 2 x 2 study design differed in three factors: the size of the mivacurium bolus dose administered, whether or not this dose was followed by an infusion of mivacurium, and in the technique used for the maintenance of anesthesia. Four groups received a single bolus dose of mivacurium, 0.15 mg/kg, and the remaining four groups received mivacurium, 0.25 mg/kg, administered iv in 15 s. Precisely 2 min later, tracheal intubation was attempted. Conditions were judged to be good or excellent on most occasions, but intubation was not possible for two of the patients in the low-dose and one in the high-dose groups. Four groups, two at each bolus dose, received no additional mivacurium: there was a dose-dependent decrease in the rate of spontaneous recovery following the bolus dose. The other subdivision of groups was the use of either barbiturate-nitrous oxide-narcotic (balanced) anesthesia, or enflurane-nitrous oxide anesthesia; the anesthetic technique did not affect the pattern of spontaneous recovery from either bolus dose. Four groups, again two at each bolus dose, subsequently received an infusion of mivacurium, adjusted to depress the twitch response by approximately 95%. Infusion rates averaged 6.0 micrograms.kg-1.min-1 in the groups receiving balanced anesthesia and 4.2 micrograms.kg-1.min-1 for those receiving enflurane anesthesia. Recovery following administration by infusion was slower than that observed following a bolus dose of mivacurium, 0.15 mg/kg but did not differ between the anesthetic groups.(ABSTRACT TRUNCATED AT 250 WORDS)