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Purpose Our hypothesis is that direct manipulation of the third and second divisions of the trigeminal nerve during microneurosurgery does not affect the incidence of trigeminocardiac reflex (TCR). The purpose of this paper was to analyze the incidence of TCR events during microneurosurgery involving the second and third divisions of the trigeminal nerve. Materials and Methods This was a retrospective cohort study of 94 patients who underwent nerve repair of the second and third divisions of the trigeminal nerve, between July 2014 and February 2021 by a single surgeon (J. Z.). The independent variables were the trigeminal nerve branch injured, the laterality of the trigeminal nerve injury, the Sunderland classification, the ASA classification, the intraoperative narcotic(s) used, and the depth of anesthesia. The dependent variables included the occurrence of intraoperative hypercapnia, hypoxia, and TCR event. Since the data was retrospective and categorical in nature, χ2 analysis was performed initially. Results None of the patients in this retrospective cohort demonstrated intraoperative hypercapnia, hypoxia or TCR events. Initial χ2 calculation was performed for the dependent variables with the trigeminal nerve groups (IAN, LN, and ION). The χ2 calculation [χ2 (1, n = 101)] was 0.2235. The P-value was .6364. Since there was no statistical significance found, there was no further analysis of surgical and anesthesia independent variables in the data collection. Conclusions The zero incidence of TCR in a large number of patients provides strong evidence supporting the rejection of the hypothesis that TCR can occur during the surgical repair of peripheral trigeminal nerves.

Background Multimodal perioperative analgesia including acetaminophen is recommended by current guidelines. The comparative efficacy of intravenous vs oral acetaminophen in sinus surgery is unknown. We aimed to determine whether intravenous or oral acetaminophen results in superior postoperative analgesia following sinus surgery. Methods This was a prospective randomized trial with blinded endpoint assessments conducted at a single large academic medical center. Subjects undergoing functional endoscopic sinus surgery were randomized to intravenous vs oral acetaminophen in addition to standard anesthetic and surgical care. The primary outcome was visual analogue scale pain score at 1 hour postoperatively. Results One hundred and ten adult patients were randomized; 9 were excluded from the data analysis. Fifty patients were assigned to intravenous acetaminophen and 51 to oral acetaminophen. Postoperative pain scores at 1 hour (primary endpoint) were not significantly different between the intravenous and oral acetaminophen groups. Similarly, there was no significant difference in pain scores at 24 hours postoperatively. Finally, there was no significant difference in postoperative opioid usage in the postanesthesia care unit or over the first 24 hours postoperatively. Conclusions This is the first comparative efficacy trial of oral vs intravenous acetaminophen in sinus surgery. There was no significant difference in pain scores at 1 or 24 hours postoperatively, and no difference in postoperative opioid use. Intravenous acetaminophen offers no apparent advantage over oral acetaminophen in patients undergoing sinus surgery. Level of evidence 1b.

This study compared the Macintosh blade direct laryngoscope, Glidescope, C-Mac d-Blade, and McGrath MAC X-blade video laryngoscopes in 2 cadaveric models with severe cervical spinal instability. We hypothesized that the Glidescope video laryngoscope would allow for intubation with the least amount of cervical spine movement. Our secondary endpoints were glottic visualization and intubation success.In total, 2 fresh cadavers underwent maximal surgical destabilization from the craniocervical junction to the cervicothoracic junction by a neurosurgical spine specialist, with subsequent neutral positioning of the heads with surgical head fixation devices. On each cadaver, 8 experienced anesthesiologists performed four intubations with the 4 laryngoscopes in random order. Lateral radiographic measurements determined vertebral displacement during intubation.Cervical spine displacements were not significantly different amongst video laryngoscopes. Cormack-Lehane Grade 1 views were achieved with all attempts with each of the 3 video laryngoscopes; intubation attempts with the Macintosh blade achieved only grade 3 or grade 4 views. Intubation was successful every time with a video laryngoscope but only during 1 of 16 intubation attempts with the Macintosh blade.In a cadaveric model with maximally destabilized cervical spines, cervical spine movement was observed during attempted laryngoscopy using each of 3 video laryngoscopes, although there was no significant difference between the laryngoscopes. Given cervical spine displacement occurred, these video laryngoscopes do not prevent cervical spine motion during laryngoscopy. However, with improved glottic visualization and intubation success, video laryngoscopes are superior to the Macintosh blade in both cervical spine safety and intubation efficacy in the model studied.

Background: The trigeminocardiac reflex (TCR) is a brainstem reflex following stimulation of the trigeminal nerve, resulting in bradycardia, asystole and hypotension. It has been described in maxillofacial and craniofacial surgeries. This case series highlights TCR events occurring during sphenopalatine ganglion (SPJ) neurostimulator implantation as part of the Pathway CH-2 clinical trial “Sphenopalatine ganglion Stimulation for Treatment of Chronic Cluster Headache”. Methods: This is a case series discussing sphenopalatine ganglion neurostimulator implantation in the pterygopalatine fossa as treatment for intractable cluster headaches. Eight cases are discussed with three demonstrating TCR events. All cases received remifentanil and desflurane for anesthetic maintenance. Results: Each patient with a TCR event experienced severe bradycardia. In two cases, TCR resolved with removal of the introducer, while the third case’s TCR event resolved with both anticholinergic treatment and surgical stimulation cessation. Conclusion: Each TCR event occurred before stimulation of the fixed introducer device, suggesting the cause for the TCR events was mechanical in origin. Due to heightened concern for further TCR events, all subsequent cases had pre-anesthesia external pacing pads placed. Resolution can occur with cessation of surgical manipulation and/or anticholinergic treatment. Management of TCR events requires communication between surgical teams and anesthesia providers, especially during sphenopalatine ganglion implantation when maxillary nerve stimulation is possible.

Background Since the effects of antiemetic doses of droperidol on the QT interval have not been previously studied, the authors designed a randomized, double-blind, placebo-controlled study to evaluate the intraoperative and postoperative effects of small-dose droperidol (0.625 and 1.25 mg intravenous) on the QT interval when used for antiemetic prophylaxis during general anesthesia. Methods One hundred twenty outpatients undergoing otolaryngologic procedures with a standardized general anesthetic technique were enrolled in this study. After anesthetic induction and before the surgical incision, 60 patients were given either saline or 0.625 or 1.25 mg intravenous droperidol in a total volume of 2 ml. A standard electrocardiographic lead II was recorded immediately before and every minute after the injection of the study medication during a 10-min observation period. The QTc (QT interval corrected for heart rate) was evaluated from the recorded electrocardiographic strips. In 60 additional patients, a 12-lead electrocardiogram was obtained before and at specific intervals up to 2 h after surgery to assess the effects of droperidol and general anesthesia on the QTc. Any abnormal heartbeats or arrhythmias during the operation or the subsequent 2-h monitoring interval were also noted. Results Intravenous droperidol, 0.625 and 1.25 mg, prolonged the QT interval by an average of 15 +/- 40 and 22 +/- 41 ms, respectively, at 3-6 min after administration during general anesthesia, but these changes did not differ significantly from that seen with saline (12 +/- 35 ms) (all values mean +/- SD). There were no statistically significant differences among the three study groups in the number of patients with greater than 10% prolongation in QTc (vs. baseline). Although general anesthesia was associated with a 14- to 16-ms prolongation of the QTc interval in the early postoperative period, there was no evidence of droperidol-induced QTc prolongation after surgery. Finally, there were no ectopic heartbeats observed on any of the electrocardiographic rhythm strips or 12-lead recordings during the perioperative period. Conclusion Use of a small dose of droperidol (0.625-1.25 mg intravenous) for antiemetic prophylaxis during general anesthesia was not associated with a statistically significant increase in the QTc interval compared with saline. More importantly, there was no evidence of any droperidol-induced QTc prolongation immediately after surgery.

Secondary tracheoesophageal puncture (TEP) placement in patients with severe limitations in neck extension is challenging. Visualization of the hypopharynx with traditional rigid endoscopy may not be possible. We report using the C-MAC (Karl Storz, Tuttlingen, Germany) video laryngoscope to successfully place a secondary TEP in patient with severe radiation fibrosis at a tertiary referral center. A 59-year-old male with severe radiation fibrosis of the neck underwent total laryngectomy for a nonfunctioning larynx. His primary TEP dislodged in the early postoperative period and the patient requested secondary TEP and voice prosthesis. The result was a successful, properly positioned, placement of a secondary TEP. Videolaryngoscopy should be included in the surgeon's armamentarium of techniques to effectively and safely perform secondary TEP in anatomically difficult patients.

UNLABELLED Propofol (Diprivan(TM); AstraZeneca, Wilmington, DE) is a commonly used drug for the induction of general anesthesia in the ambulatory setting. With the availability of a new bisulfite-containing generic formulation of propofol, questions have arisen regarding its cost effectiveness and safety compared with Diprivan(TM). Two hundred healthy outpatients were randomly assigned, according to a double-blinded protocol, to receive either Diprivan(TM) or bisulfite-containing propofol 1.5 mg/kg IV as part of a standardized induction sequence. Maintenance of anesthesia consisted of either desflurane (4%-8% end-tidal) or sevoflurane (1%-2% end-tidal) in combination with a remifentanil infusion (0.125 microg x kg(-1) x min(-1) IV). Patient assessments included pain on injection, induction time, hemodynamic and bispectral electroencephalographic changes during induction, emergence time, and incidence of postoperative nausea and vomiting. The two propofol groups were comparable demographically, and the induction times and bispectral index values during the induction were also similar. However, the bisulfite-containing formulation was associated with less severe pain on injection (5% vs 11%), with fewer patients recalling pain on injection after surgery (38% vs. 51%, P

UNLABELLED The optimal dose and timing of 5-HT(3) antagonist administration for prophylaxis against postoperative nausea and vomiting (PONV) remains controversial. Although 5-HT(3) antagonists seem to be most effective when administered near the end of surgery, there are no data on the comparative efficacy or costs associated with the 5-HT(3) antagonists dolasetron and ondansetron when administered at the end of the operation. In this double-blinded study, 200 outpatients undergoing otolaryngologic procedures with a standardized general anesthetic received 4 (O4) or 8 mg (O8) of ondansetron or 12.5 (D12.5) or 25 mg (D25) of dolasetron IV within 30 min before the end of surgery. A blinded observer recorded the emetic episodes, maximum nausea score, recovery room resource and drug use, nursing time spent managing PONV, times to achieve discharge criteria from the Phase 1 and 2 recovery units, postdischarge emesis, and patient satisfaction. Total costs were calculated by using the perspective of a free-standing surgicenter. There were no differences in patient demographics, incidence of PONV, need for rescue medications, time spent in the recovery areas, unanticipated hospital admissions, or patient satisfaction among the four treatment groups. The mean total costs (95% confidence intervals) to prevent PONV in one patient were lowest in the D12.5 group: $23.89 (17.18-28.79) vs $37.81 (30.29-45.32), $33.91 (28.92-39.35), and $75.18 (61.13-89.24) for D25, O4, and O8, respectively. Excluding nursing labor costs did not alter this finding: $18.51 (14.18-22.85), $34.77 (28.03-41.49), $31.77 (28. 92-39.35), and $71.76 (58.17-85.35) for D12.5, D25, O4, and O8, respectively. We conclude that 12.5 mg of dolasetron IV is more cost effective than 4 mg of ondansetron IV for preventing PONV after otolaryngologic surgery and is associated with similar patient satisfaction. IMPLICATIONS When administered at the end of surgery, 12.5 mg of dolasetron IV is as effective as 25 mg of dolasetron IV, 4 mg of ondansetron IV, and 8 mg of ondansetron IV in preventing emetic symptoms after otolaryngologic surgery and was associated with similar patient satisfaction at a reduced cost. There were no differences in the antiemetic efficacy of the 4 and 8 mg doses of ondansetron.

Background The cuffed oropharyngeal airway is a modified Guedel-type oral airway with a cuff at its distal end. The objectives of this study were to compare the ability of the cuffed oropharyngeal airway and the laryngeal mask airway to provide positive-pressure ventilation during general anesthesia, and to assess their relative ease of use and ability to reduce total fresh gas flow rates. Methods In this prospective, randomized study, a cuffed oropharyngeal airway (n = 25) or a laryngeal mask airway (n = 25) device was inserted after induction of anesthesia intravenously using 2 mg/kg propofol. While anesthesia was maintained with sevoflurane and nitrous oxide, the leak pressure, leak fraction (the fractional difference between the inspired and expired tidal volume), minimum fresh gas flow rate, and need for airway manipulations were determined. The anesthesia provider who inserted the device completed an evaluation form at the end of the 15-min study period. Results Positive-pressure ventilation was established successfully on the first attempt in 92% of the patients when the cuffed oropharyngeal airway was used and in 88% of the patients when the laryngeal mask airway device was used. However, manipulations of the airway device were necessary more frequently (8 vs. 1 patient; P < 0.05) and the leak pressure was less (22 +/- 6 cm water vs. 26 +/- 5 cm water; P < 0.05) with the cuffed oropharyngeal airway than with the laryngeal mask airway. In addition, the leak fraction (0.19 +/- 0.18 vs. 0.31 +/- 0.22; P < 0.05) and the minimum fresh gas flow rate (1.3 +/- 1.5 vs. 2.4 +/- 2.5; P = 0.12) were less in the laryngeal mask airway group. Conclusions Positive-pressure ventilation is possible with the laryngeal mask airway and cuffed oropharyngeal airway devices. Although the cuffed oropharyngeal airway can be inserted easily by inexperienced users with a high first-attempt success rate (> 90%), manipulations of the device may be required to maintain a patent airway. The laryngeal mask airway device allows positive-pressure ventilation at slightly greater peak inspiratory pressures.

Objective. Reliable closed loop infusion systems for regulating paralysis level can be a great convenience to the anesthesiologists in automating their task. This paper describes the in vivo performance evaluation of a self-tuning controller that is designed to accommodate large varations in patient drug sensitivity, drug action delays and environmental interfering noise. Methods. The infusion system was evaluated in six adult mongrel dogs. Following the manual induction of paralysis by an anesthesiologist, the controller regulated the infusion of vecuronium to maintain a desired level of paralysis. The integrated EMG response of the hypothenar muscle to a train-of-four stimulation of the ulnar nerve quantified the depth of paralysis. The controller's robustness was tested by contaminating the sensed twitch signal with electrocautery noise and electrode disconnection. Results. The controller reached the initial level of paralysis of 100% in about 4.0 minutes and arrived at the desired level of 90% with an overshoot of 6.38% (±6.82). It maintained the desired level of paralysis with a 2.04% (±1.20) mean offset at 90% and 0.4% (±0.5) mean offset at 80% steady state level, respectively. The mean infusion rate to sustain 90% and 80% paralysis were 2.70 (±2.05) and 2.15 (±2.57) ((mg/kg)/min), respectively. Conclusions. The system adapted to a large variation in the sample subject drug sensitivity. It remained stable despite large amplitude disturbances and maintained the paralysis at the desired level following the removal of the disturbances.

To determine the optimal dose of nicardipine (N) for maintenance of hemodynamic stability during the postinduction period, we designed a randomized, double-blind, placebo-controlled, dose-ranging study using four different doses of N administered after a standardized anesthetic induction sequence. A total of 106 patients were assigned to one of the following treatment groups: saline (control), N 0.5 mg (N0.5), N 1 mg (Nl), N 2 mg (N2), and N 4 mg (N4). The study medication was administered intravenously (IV) in 2.5 mL of saline over 30 s 2 min before laryngoscopy. Mean arterial pressure (MAP) and heart rate (HR) were recorded at 1-min intervals for 15 min after tracheal intubation and for 5 min after skin incision. After intubation, the peak MAP values differed from the preinduction baseline MAP values by 21% 2 20%, 9% + 12%, 1% + 13%, -10% ? 12%, and -15% ? 13% (mean ? SD) in the control, N0.5, Nl, N2, and N4 groups, respectively. However, the percent change in the pre- to postintubation MAP values (37% to 47%) was similar in all five groups. The highest postintubation HR values were recorded in the N4 group (P < 0.05 versus the other groups). However, the increases in MAP values after skin incision were the least in the N4 group. In conclusion, Nl IV, administered 2 min before laryngoscopy provides optimal control of arterial blood pressure during the postinduction period. Implications: Acute increases in blood pressure during anesthesia are undesirable in patients with preexisting cardiovascular diseases. This double-blind study found that the calcium-channel blocker, nicardipine, 1 mg intravenously 2 min before tracheal intubation maintained hemodynamic stability during the intraoperative period. (Anesth Analg 1997;85:1247-51)

To assess the safety and efficacy of transoermal fentanyl plus im ketorolac vs im ketorolac alone in the treatment of postoperative pain. Ninety-two patients scheduled for surgery involving moderate to severe postoperative pain were randomized to one of two groups. Group A (n=46) received an active fentanyl patch and group P (n=46) received a placebo patch. Patches remained in place for 24 hr. Each patient received intraoperative ketorolac, 60 mgim. Patients were monitored for 36 hr postoperatively and the groups were analyzed for ketorolac usage, pain scores. vital signs, serum fentanyl concentrations, and adverse events. Intramuscular ketorolac was available on demand. Group A had lower pain scores at 8, 12, 16 and 24 hr after patch placement (P< 0.05). Group A had lower heart rates, lower respiratory rates and fewer dropouts due to inadequate pain relief (4.3% vs 21.7%, P< 0.05). Group A patients also used less ketorolac than group P patients (P< 0.05). The incidence of pruntus was higher in group A patients (19%vs 2%, P< 0.05), while the incidence of nausea and vomiting was not different between the two groups. Transdermal fentanyl was adequate “stand-alone” analgesia in only 23.8% of group A patients while 93.7% of the remaining group A patients receiving a combination of transdermal fentanyl and ketorolac had adequate pain relief. The transdermal fentanyl delivery system plus ketorolacim was more effective in controlling postoperative pain than ketorolacim alone. The two treatment modalities were comparable in safety with no difference in serious adverse events.

A randomized, double-blind, placebo-controlled study was designed to compare the relative efficacy of prophylactic ondansetron, 4 mg intravenously (IV), when administered before induction of anesthesia or at the end of surgery to an outpatient population at high risk of developing postoperative nausea and vomiting (PONV). Patients undergoing otolaryngologic surgery were randomly assigned to one of three different treatment groups: Group 1 (placebo) received saline 5 mL prior to induction of anesthesia and again at the end of surgery; Group II received ondansetron 4 mg in 5 mL prior to induction of anesthesia and saline 5 mL at the end of surgery; and Group III received saline 5 mL prior to induction of anesthesia and ondansetron 4 mg at the end of surgery. All patients received the same general anesthetic technique. A standardized regimen of rescue antiemetics was administered in the recovery room to patients with > or = 2 emetic episodes or at the patients request for persistent nausea. Episodes of nausea and vomiting, as well as the need for rescue antiemetics, were recorded for 24 h after the operation. The incidences of nausea and emesis in the recovery room after prophylactic ondansetron, 4 mg IV, administered either before induction (68% and 20%, respectively) or at the end of surgery (60% and 4%, respectively) were not significantly decreased compared to the placebo control group (80% and 12%, respectively). However, when ondansetron was administered at the end of the operation, it significantly reduced the need for rescue antiemetics in the recovery room (36% vs 64% in the control group). The postanesthesia care unit and hospital discharge times were similar in all three study groups. One patients in Group II and one patient in Group III were hospitalized because of intractable symptoms related to PONV. After discharge from the ambulatory surgery unit, the incidence of nausea, vomiting, and the need for rescue antiemetic drugs were similar in all three treatment groups. In conclusion, ondansetron (4 mg IV) was more effective in reducing the need for rescue antiemetics in the recovery room when administered at the end versus prior to the start of otolaryngologic surgery. Therefore, when ondansetron is used for antiemetic prophylaxis in outpatients undergoing otolaryngologic procedures, it should be administered at the end of the operation rather than prior to induction of anesthesia.

Three different anesthetic techniques were compared in 146 healthy outpatients undergoing ambulatory surgery. In Groups I and II, anesthesia was induced with propofol (1.5-2.0 mg/kg, intravenously [iv]) and maintained with nitrous oxide (N2O) 60% in oxygen and either a propofol infusion, 75-160 micrograms.kg-1.min-1 IV, or sevoflurane, 1%-2% end-tidal, respectively. In Group III, anesthesia was induced and maintained with sevoflurane, 1%-4% end-tidal and N2O 60% in oxygen. In addition to 60% N2O in oxygen at a total gas flow of 3 L/min, all patients received fentanyl, 2-3 micrograms/kg IV, and vecuronium, 0.1 mg/kg IV. IV induction of anesthesia with propofol (90 +/- 53 s and 94 +/- 48 s in Groups I and II, respectively) was significantly faster than inhalation induction with sevoflurane (153 +/- 100 s). There were no significant differences in the incidence of coughing, airway irritation, or laryngospasm during induction of anesthesia. Although the mean arterial blood pressure values were similar in all three groups, the use of sevoflurane was associated with consistently lower heart rate values during the early maintenance period. Early and intermediate recovery times were the same in all three treatment groups. The use of sevoflurane for induction and/or maintenance of anesthesia was associated with a higher incidence of postoperative emetic sequelae compared with propofol. Finally, the times at which patients were considered "fit for discharge" and the actual discharge times were similar in all three groups. Sevoflurane is an acceptable alternative to propofol for induction and maintenance of outpatient anesthesia.

This paper describes a new adaptive controller that is capable of accommodating changes in the time delay of linear systems with unknown or time-varying time delay. The derivation of the controller is based on a discrete formulation of the modified Smith delay compensator and a self-tuning control strategy. In addition to accommodating the time delay changes, the controller rejects load disturbances without requiring an estimate of the disturbance or producing an offset in the output.

Pregabalin is a gabapentinoid compound, which has been alleged to possess anxiolytic, analgesic, and anticonvulsant properties. We hypothesized that premedication with oral pregabalin would produce dose-related reductions in acute (state) anxiety and increases in sedation (sleepiness) before induction of general anesthesia. A secondary objective was to determine if premedication with pregabalin would reduce postoperative pain.One hundred eight ASA I-III outpatients undergoing elective surgery were randomly assigned to one of the four premedication treatment groups: 1) control group received placebo capsules, 2) pregabalin 75 group received pregabalin 75 mg, po, 3) pregabalin 150 group received pregabalin 150 mg, po, and 4) pregabalin 300 group received pregabalin 300 mg, po. The effects of the study drug on the patients' level of anxiety, sedation, and pain were assessed at baseline (immediately before study drug administration), at 30 and 60 min after drug administration, and immediately before induction of anesthesia, as well as at 30-min intervals in the postanesthesia care unit (PACU) using standardized 11-point verbal rating scales, with 0 = none to 10 = maximal effect. The need for postoperative opioid analgesic medication, incidence of nausea and vomiting, requirement for rescue antiemetics, and times to discharge from the PACU and hospital, as well as the patients' quality of recovery scores, and late recovery outcomes (e.g., resumption of dietary intake and recovery of bowel function) were assessed at a 7-day follow-up interview.Demographic characteristics, times between study drug administration to anesthetic induction, type of surgical procedures, duration of anesthesia, PACU and hospital discharge time, as well as the requirement for fentanyl in the PACU, did not differ among the four study groups. Anxiety levels remained unchanged during the preoperative evaluation period, and did not differ among the four study groups. Sedation scores were significantly higher in the pregabalin 300 group at the preinduction assessment interval and at 90 and 120 min after surgery compared with the control group (5 +/- 3 vs 3 +/- 2, 7 +/- 4 vs 5 +/- 3, 8 +/- 4 vs 4 +/- 4, respectively, P0.05).Preoperative pregabalin administration (75-300 mg po) increased perioperative sedation in a dose-related fashion, but failed to reduce preoperative state anxiety, postoperative pain, or to improve the recovery process after minor elective surgery procedures.

BACKGROUND: Sugammadex is a modified cyclodextrin compound, which encapsulates rocuronium to provide for a rapid reversal of residual neuromuscular blockade. We tested the hypothesis that sugammadex would provide for a more rapid reversal of a moderately profound residual rocuronium-induced blockade than the commonly used cholinesterase inhibitors, edrophonium and neostigmine. METHODS: Sixty patients undergoing elective surgery procedures with a standardized desflurane–remifentanil–rocuronium anesthetic technique received either sugammadex, 4 mg/kg IV (n 20), edrophonium, 1 mg/kg IV and atropine, 10 g/kg IV (n 20), or neostigmine, 70 g/kg IV and glycopyrrolate, 14 g/kg IV (n 20) for reversal of neuromuscular blockade at 15 min or longer after the last dose of rocuronium using acceleromyography to record the train-of-four (TOF) responses. Mean arterial blood pressure and heart rate values were recorded immediately before and for 30 min after reversal drug administration. Side effects were noted at discharge from the postanesthesia care unit. RESULTS: The three groups were similar with respect to their demographic characteristics and total dosages of rocuronium prior to administering the study medication. Although the initial twitch heights (T1) at the time of reversal were similar in all three groups, the time to achieve TOF ratios of 0.7 and 0.9 were significantly shorter with sugammadex (71 25 and 107 61 s) than edrophonium (202 171 and 331 27 s) or neostigmine (625 341 and 1044 590 s). All patients in the sugammadex group achieved a TOF ratio of 0.9 5 min after reversal administration compared with none and 5% in the edrophonium and neostigmine groups, respectively. Heart rate values at 2 and 5 min after reversal were significantly higher in the neostigmineglycopyrrolate group compared with that in sugammadex. Finally, the incidence of dry mouth was significantly reduced in the sugammadex group (5% vs 85% and 95% in the neostigmine and edrophonium groups, respectively). CONCLUSION: Sugammadex, 4 mg/kg IV, more rapidly and effectively reversed residual neuromuscular blockade when compared with neostigmine (70 g/kg IV) and edrophonium (1 mg/kg IV). Use of sugammadex was associated with less frequent dry mouth than that with the currently used reversal drug combinations. (Anesth Analg 2007;104:569‐74)

This paper describes an adaptive control strategy that is suited for automatic control of mean arterial pressure. The performance of the control was evaluated for application of sodium nitroprusside, a vasodilator drug, using a computer simulation with a model of the patient response derived from actual patient data. One feature of the controller is its ability to optimize the quantity of infused drug without generating an offset in the controlled pressure. A comparison with another control strategy which has been employed in the clinics is presented.

Since the effects of antiemetic doses of droperidol on the QT interval have not been previously studied, the authors designed a randomized, double-blind, placebo-controlled study to evaluate the intraoperative and postoperative effects of small-dose droperidol (0.625 and 1.25 mg intravenous) on the QT interval when used for antiemetic prophylaxis during general anesthesia.One hundred twenty outpatients undergoing otolaryngologic procedures with a standardized general anesthetic technique were enrolled in this study. After anesthetic induction and before the surgical incision, 60 patients were given either saline or 0.625 or 1.25 mg intravenous droperidol in a total volume of 2 ml. A standard electrocardiographic lead II was recorded immediately before and every minute after the injection of the study medication during a 10-min observation period. The QTc (QT interval corrected for heart rate) was evaluated from the recorded electrocardiographic strips. In 60 additional patients, a 12-lead electrocardiogram was obtained before and at specific intervals up to 2 h after surgery to assess the effects of droperidol and general anesthesia on the QTc. Any abnormal heartbeats or arrhythmias during the operation or the subsequent 2-h monitoring interval were also noted.Intravenous droperidol, 0.625 and 1.25 mg, prolonged the QT interval by an average of 15 +/- 40 and 22 +/- 41 ms, respectively, at 3-6 min after administration during general anesthesia, but these changes did not differ significantly from that seen with saline (12 +/- 35 ms) (all values mean +/- SD). There were no statistically significant differences among the three study groups in the number of patients with greater than 10% prolongation in QTc (vs. baseline). Although general anesthesia was associated with a 14- to 16-ms prolongation of the QTc interval in the early postoperative period, there was no evidence of droperidol-induced QTc prolongation after surgery. Finally, there were no ectopic heartbeats observed on any of the electrocardiographic rhythm strips or 12-lead recordings during the perioperative period.Use of a small dose of droperidol (0.625-1.25 mg intravenous) for antiemetic prophylaxis during general anesthesia was not associated with a statistically significant increase in the QTc interval compared with saline. More importantly, there was no evidence of any droperidol-induced QTc prolongation immediately after surgery.

This report is the fourth in a series of reports on the implementation of interoperability and information assurance (IA) policies within DoD. This report addresses the Air Force's implementation of those policies in the Joint Capabilities Integration and Development System, inclusion of adequate interoperability key performance parameters (KPPs) in requirements documents, and the interoperability certification process for Air Force acquisition programs.

UNLABELLED Using a randomized, double-blind protocol design, we compared a new lower-lipid emulsion of propofol (Ampofol) containing propofol 1%, soybean oil 5%, and egg lecithin 0.6% with the most commonly used formulation of propofol (Diprivan) with respect to onset of action and recovery profiles, as well as intraoperative efficacy, when administered for induction and maintenance of general anesthesia as part of a "balanced" anesthetic technique in 63 healthy outpatients. Anesthesia was induced with sufentanil 0.1 microg/kg (or fentanyl 1 microg/kg) and propofol 2 mg/kg IV and maintained with a variable-rate propofol infusion, 120-200 microg x kg(-1) x min(-1). Onset times to loss of the eyelash reflex and dropping a syringe were recorded. Severity of pain on injection, speed of induction, intraoperative hemodynamic variables, and electroencephalographic bispectral index values were assessed. Recovery times to opening eyes and orientation were noted. The results demonstrated that there were no significant differences between Ampofol and Diprivan with respect to onset times, speed of induction, anesthetic dose requirements, bispectral index values, hemodynamic variables, recovery variables, or patient satisfaction. However, the incidence of pain on injection was more frequent in the Ampofol group (26% versus 6%, P < 0.05). We conclude that Ampofol is equipotent to Diprivan with respect to its anesthetic properties but was associated with a more frequent incidence of mild pain on injection. IMPLICATIONS The pharmacodynamic profile of a lower-lipid containing emulsion of propofol (Ampofol) was compared with Diprivan when administered for induction and maintenance of general anesthesia. This preliminary study demonstrated that the two formulations of propofol were equivalent with respect to their induction and maintenance properties. However, Ampofol was associated with a more frequent incidence of pain on injection.

UNLABELLED: We designed this randomized, double-blinded, placebo-controlled study to compare the analgesic effect of the cyclooxygenase-2 inhibitors rofecoxib and celecoxib with acetaminophen when administered before outpatient otolaryngologic surgery in 240 healthy subjects. Patients were assigned to one of four study groups: Group 1, control (vitamin C 500 mg); Group 2, acetaminophen 2 g; Group 3, celecoxib 200 mg; or Group 4, rofecoxib 50 mg. The first oral dose of the study medication was administered 15-45 min before surgery, and a second dose of the same medication was given on the morning after surgery. Recovery times, side effects, pain scores, and the use of rescue analgesics were recorded. Follow-up evaluations were performed at 24 and 48 h after surgery to assess postdischarge pain, analgesic requirements, nausea, and patient satisfaction with their postoperative pain management and quality of recovery. The need for rescue analgesia and peak pain scores were used as the primary end points for estimating efficacy, and the costs to achieve complete satisfaction with analgesia were used for the cost-efficacy comparisons. Premedication with oral rofecoxib (50 mg) or celecoxib (200 mg) was more effective than placebo in reducing postoperative pain scores and analgesic requirements in the postoperative care unit and after discharge. The analgesic efficacy of oral acetaminophen (2 g) was limited to the postdischarge period. Patient satisfaction with pain management was improved in all three treatment groups compared with placebo but was higher with celecoxib and rofecoxib compared with acetaminophen. Rofecoxib was also more effective than celecoxib in reducing pain and improving patient satisfaction after otolaryngologic surgery. Rofecoxib achieved complete satisfaction with pain control in one additional patient, who would not have otherwise been satisfied, at lower incremental costs to the institution compared with celecoxib. We conclude that rofecoxib 50 mg orally is more cost-effective for reducing postoperative pain and improving patient satisfaction with their postoperative pain management than celecoxib (200 mg) or acetaminophen (2 g) in the ambulatory setting. IMPLICATIONS: Oral premedication with rofecoxib (50 mg) was more effective than celecoxib (200 mg) and acetaminophen (2 g) in reducing postoperative pain and in improving the quality of recovery and patient satisfaction with pain management after outpatient otolaryngologic surgery with only a small increase in cost of care.

We report on a new optic laryngoscope blade that provides two views of the larynx during tracheal intubation. The availability of an alternative direct view of the larynx may improve the ability of anesthesia providers to observe the tracheal tube passing through the vocal cords when using a Macintosh laryngoscope blade. The optic port improved visualization of passage of the endotracheal tube in obese patients. However, further studies are needed in patients with difficult airways to determine whether this new blade will ease the ability of practitioners to insert a tracheal tube.

This paper presents a model-base controller for control of induced paralysis during surgery. The controller relies on genetic optimization algorithm for estimating the response model parameters as well as computing the necessary infusion rates.

Background Nonsteroidal antiinflammatory drugs are commonly administered as part of a multimodal regimen for pain management in the ambulatory setting. This randomized, double-blinded, placebo-controlled study was designed to compare the analgesic effect of oral rofecoxib, a cyclooxygenase-2 inhibitor, and acetaminophen when administered alone or in combination prior to outpatient otolaryngologic surgery. Methods A total of 143 healthy outpatients undergoing elective otolaryngologic surgery were assigned to one of four study groups: group 1 = control (500 mg vitamin C); group 2 = 2 g acetaminophen; group 3 = 50 mg rofecoxib; or group 4 = 2 g acetaminophen and 50 mg rofecoxib. The first oral dose of the study medication was taken 15-45 min before surgery, and a second dose of the same medication was administered on the morning after surgery. Recovery times, side effects, and the need for rescue analgesics were recorded. Follow-up evaluations were performed at 24 and 48 h after surgery to assess postdischarge pain, analgesic requirements, nausea, and patient satisfaction with their postoperative pain management and quality of recovery. Peak pain scores and the need for rescue analgesic medication were used as the endpoints for estimating efficacy of the study drugs, while cost to achieve complete satisfaction with analgesia was used in the cost-effectiveness analysis. Results Premedication with rofecoxib (50 mg) was significantly more effective than either placebo or acetaminophen (2 g) in reducing the peak postoperative pain, the need for analgesic medication, and improving the quality of recovery and patient satisfaction. Moreover, the addition of acetaminophen failed to improve its analgesic efficacy. An expenditure for rofecoxib of 16.76 US dollars (95% confidence interval, 7.89 to 21.03 US dollars) and 30.24 US dollars (95% confidence interval, 5.25 to 54.20 US dollars) would obtain complete satisfaction with pain control in one additional patient who would not have been satisfied if placebo or acetaminophen, respectively, had been administered prior to surgery. Conclusions Rofecoxib, 50 mg administered orally, decreased postoperative pain and the need for analgesic rescue medication after otolaryngologic surgery. The addition of 2 g oral acetaminophen failed to improve its analgesic efficacy.

Non-opioid analgesics are often used to supplement opioids for the management of perioperative pain. In this randomized, double-blinded, placebo-controlled study, we examined the effects of acetaminophen and a cyclooxygenase type-2 inhibitor, celecoxib, when administered alone or in combination, before elective otolaryngologic surgery in 112 healthy outpatients. Subjects were assigned to 1 of 4 study groups: Group 1, placebo (vitamin C, 500 mg per os [PO]); Group 2, acetaminophen 2000 mg PO; Group 3, celecoxib 200 mg PO; or Group 4, acetaminophen 2000 mg and celecoxib 200 mg PO. All patients received a standardized anesthetic technique. During the postoperative period, pain was assessed using a 10-point verbal rating scale. Recovery times, the need for rescue analgesics, side effects, and patient satisfaction scores were also recorded. The combination of acetaminophen and celecoxib was significantly more effective than placebo in reducing postoperative pain. Celecoxib, when administered alone or in combination with acetaminophen, improved patients' satisfaction with their postoperative analgesia. With the combination of acetaminophen and celecoxib, an additional expenditure of $6.16 would be required to obtain complete satisfaction with postoperative pain management in one additional patient who would not have been completely satisfied if he/she had received the placebo. However, oral celecoxib or acetaminophen alone was not significantly more effective than placebo in reducing postoperative pain when administered before surgery. We conclude that oral premedication with a combination of acetaminophen (2000 mg) and celecoxib (200 mg) was highly effective in decreasing pain and improving patient satisfaction after outpatient surgery.Oral premedication with a combination of acetaminophen (2000 mg) and celecoxib (200 mg) was effective in decreasing pain and improving patient satisfaction after otolaryngologic surgery. However, acetaminophen (2000 mg) or celecoxib (200 mg) alone was not significantly more effective than placebo in reducing postoperative pain.

We examined the effect of four maintenance anaesthetics on the neuromuscular blocking activity and spontaneous recovery characteristics after a short-term infusion of rapacuronium. Eighty ASA I-III adult patients undergoing elective surgery were studied at four centres. Anaesthesia was induced with propofol 1.5-2.5 mg kg-1 and fentanyl 1-2 micrograms kg-1, followed by a bolus of rapacuronium 1.5 mg kg-1. The patients were randomized to receive either desflurane (2-4% end-tidal, ET), sevoflurane (0.75-1.5% ET), isoflurane (0.4-0.8% ET), or a propofol infusion (75-150 micrograms kg-1 min-1) for maintenance of anaesthesia in combination with nitrous oxide (60-70%) in oxygen. When the first twitch (T1) of a train-of-four stimulus (using the TOF Guard accelerometer) returned to 5%, an infusion of rapacuronium was started at 3 mg kg-1 h-1 and adjusted to maintain T1/T0 at 10%. The duration of infusion lasted between 45 and 60 min, and the average infusion rates of rapacuronium were similar in all groups, ranging from 1.6 to 2.5 mg kg-1 h-1. There were no significant differences among the groups in the times for T1/T0 to return to 25%, 75% or 90%, or for T4/T1 to return to 70% and 80% upon discontinuation of the infusion. When potent inhalation anaesthetics are used in clinically relevant concentrations for maintenance of anaesthesia, the neuromuscular recovery profile of rapacuronium administered as a variable-rate infusion for up to 1 h is similar to that found with a propofol-based anaesthetic technique.

There is no agreement as to appropriate fluid resuscitation in patients undergoing liposuction. This has assumed greater significance, as surgeons have undertaken larger volume aspirations (or = 4 liters) and the potential complications of hypovolemia and fluid overload have materialized. This prospective study of 53 consecutive healthy patients undergoing liposuction using a superwet technique served to develop general guidelines for safe perioperative fluid management, especially in regard to large-volume aspirations. In this context, "aspirate" is defined as the total fat and fluid that is removed during liposuction. All patients were monitored using standard noninvasive hemodynamic monitoring. Thirty-six patients were monitored perioperatively with Foley catheters. The 53 patients underwent liposuction alone. We did not include patients who underwent concurrent aesthetic surgical procedures because our intention was to establish fluid administration guidelines for the liposuction patient. There were no significant complications in our series. The intraoperative fluid ratio, defined as (intravenous fluid + infiltrate)/aspirate, was 2.1 for the small-volume group and 1.4 for the large-volume group. These values were significantly different (p.001, t test). Average urine output in the operating room and recovery room and on the floor was satisfactory (0.5 to 1 cc/kg/hr) and did not relate to volume aspirated (p = 0.21, 0.91, and 0.6, respectively, t test). Four patients who underwent "large-volume" aspirations (or = 4 liters) had transient hypotension, which was immediately responsive to crystalloid fluid boluses in the first postoperative hours. All other patients required only maintenance intravenous crystalloid postoperatively until oral intake had been resumed. There were no statistically significant differences in postoperative fluid administration between the small- and large-volume groups. Ninety-three percent of patients were discharged within 24 hours of surgery. Our suggested guidelines for fluid resuscitation based on this retrospective study are as follows: (1) small volume (4 liters aspirated): maintenance fluid + subcutaneous wetting solution; (2) large volume (or = 4 liters aspirated): maintenance fluid + subcutaneous wetting solution + 0.25 cc of intravenous crystalloid per cc of aspirate removed after 4 liters. This formula has since been used in the care of 94 patients who have undergone liposuction exclusively. All patients have had unremarkable hospital courses. These guidelines do not replace sound clinical judgment. Good communication between the surgeon and anesthesiologist is critical to optimal patient care and safety.

We evaluated the effect of transdermal scopolamine on the incidence of postoperative nausea and vertigo after outpatient ear surgery (exploratory tympanotomy, mastoidectomy, or endolymphatic sac and oval and round window surgery) in a double-blind, placebo-controlled study. A transdermal patch containing either scopolamine (n = 19) or placebo (n = 20) was placed behind the nonsurgical ear 2 h before surgery. Anesthesia was induced with thiopental (4-6 mg/kg intravenously [i.v.]), sufentanil (0.5 microgram/kg i.v.), and vecuronium (0.1 mg/kg i.v.) and maintained with isoflurane (0.2%-2%) and nitrous oxide (70%) in oxygen. Patients were observed postoperatively in the recovery room and after discharge for 72 h. There was no significant difference between groups with respect to time in recovery room, time to discharge, incidence of in-house nausea, vomiting, amount of antiemetics required, or postoperative visual analog scale (VAS) scores while in the hospital. After discharge, there were lower VAS nausea scores (by repeat measures analysis, P < 0.05) and a lower reported incidence of nausea (31% vs 62%; P < 0.05) and vertigo (6.2% vs 25%; P < 0.05) in the active patch group versus the placebo group. There was a higher incidence of dry mouth in the active patch group (44% vs 25%). Seven patients did not complete the study due to failure to keep the patch in place or failure to return the diary from home; and one patient from the placebo patch group was admitted for uncontrolled nausea and vomiting. The authors concluded that transdermal scopolamine is effective in reducing, but not eliminating, postoperative nausea and vertigo after discharge in outpatient ear surgery.

This paper presents a strategy for automatic control of induced paralysis using vecuronium bromide during surgery. The controller is self-tuning and adapts to inter-patient and intra-patient response variations while optimizing the output variance and infusion rate. In particular, the controller is capable of accommodating the variations of pure time delays in patient response. The performance of the controller is evaluated using an experimentally derived pharmacokinetic and nonlinear pharmacodynamic model of patient response. The results indicate that the controller provides robust regulation of the paralysis level with no output offset.

BACKGROUND: Autonomic reflex dysfunction in patients with diabetes is associated with an increased incidence of hypotension after induction of anesthesia. Whether this finding can be extrapolated to patients with autonomic dysfunction from other causes (e.g., advanced age, hypertension, altered ventricular function) has not been established. METHODS: The authors investigated whether autonomic reflex dysfunction in a more generalized patient group (26 consecutively consenting day-surgery patients older than 39 yr) was similarly associated with the occurrence of hypotension after induction. Preoperative tests of autonomic function included: Valsalva maneuver, change in heart rate with forced breathing, change in heart rate and blood pressure with standing, and spectral analysis of heart rate variability. Anesthesia was induced with 3-5 mg/kg thiopental, 2 micrograms/kg fentanyl, and 60% N2O; 0.1 mg/kg vecuronium was used for paralysis; 0-1.5% isoflurane was added for maintenance of anesthesia after intubation. Noninvasive measurements of mean blood pressure were obtained every minute for 10 min after induction and then every 3 min until skin incision. RESULTS: Twelve patients developed hypotension (mean blood pressure < 70 mmHg), and 14 patients did not. Measurements of autonomic reflex function were significantly more abnormal in the patients who developed hypotension (P < 0.006 for Valsalva measurements, heart rate variability parameters, and change in heart rate with forced breathing). Using critical test values for autonomic tests, the incidence of hypotension was 67-83% in patients with autonomic nervous system dysfunction versus 9-17% in other patients. CONCLUSIONS: The results document that: (1) some degree of autonomic reflex dysfunction is not uncommon in patients older than 39 yr presenting for elective surgery, and (2) such dysfunction is associated with an increased incidence of hypotension when using the described induction technique.

Study Objective : To evaluate the effect of ketorolac tromethamine on coagulation using thrombelastography (TEG). Design : TEGs were performed in each patient before and after ketorolac administration. Each patient's predrug results were used as control measurements for comparison with the postdrug results. Setting : Medical center surgical unit. Patients : Twenty ASA physical status I and II patients undergoing minor elective surgery; 12 healthy volunteers. Interventions : TEGs were performed in all subjects before and 60 minutes after the intramuscular (IM) administration of ketorolac tromethamine 60 mg. Ten surgical patients were studied in the intraoperative period, and 10 surgical patients were studied in the postoperative period. The 12 healthy volunteers did not undergo a surgical procedure. Measurements and Main Results : Specific parameters assessed from, the TEGS were reaction time (R time), coagulation time (RK time), clot formation rate (angle of deflection), and maximum clot strength (maximum amplitude of deflection). Ketorolac administration did not cause statistically significant changes in these parameters in any of the three groups studied. Conclusions : IM administration of ketorolac tromethamine 60 mg did not significantly alter the speed of formation or viscoelastic strength of clots as measured by TEG. These results provide additional support for prior clinical studies confirming the safety of ketorolac administration in the perioperative period.

Performance of an adaptive controller for automatic regulation of level of induced paralysis during surgery, using vecuronium bromide, is presented. In addition to adapting to variations in patient dynamic response parameters, the controller accommodates any variation in the pure time delays of the response. The performance results are obtained from a computer simulation of the nonlinear patients pharmacokinetic and pharmacodynamic response to the drug.

Study Objective: To assess the value of end-tidal anesthetic gas monitoring with respect to intraoperative hemodynamic stability and recovery times. Design: Randomized blinded study. Setting: Operating rooms at a university teaching hospital. Patients: 120 ASA I and II patients receiving general anesthesia maintained with isoflurane and nitrous oxide (N 2 O). Interventions: Following a standardized induction technique, patients were assigned to either an end-tidal isoflurane monitored (n = 60) or unmonitored (n = 60) group. During each operation, the anesthesiologist attempted to maintain an adequate "depth of anesthesia" by varying the administered concentration of isoflurane with or without information from an end-tidal isoflurane monitor. Intraoperative hemodynamic stability was assessed by determining the variation from a preincisional "baseline" mean arterial pressure (MAP) value established during a 10 minute interval immediately prior to the surgical incision. Recovery times were recorded from discontinuation of isoflurane and N 2 O until awakening, orientation, and postanesthesia care unit discharge. Measurements and Main Results: Intraoperative hemodynamic stability was assessed in each patient and reported as the average error from the baseline MAP, absolute average error from the baseline MAP, coefficients of variation of heart rate (HR), systolic and diastolic MAP, and end-tidal isoflurane concentrations. Both study groups had similar intraoperative MAP and HR values, average error and coefficients of variation for the hemodynamic variables, as well as similar numbers of episodes of hypertension, hypotension, tachycardia, and bradycardia. Finally, the two groups were comparable with respect to early recovery times and postoperative side effects. Conclusions: This study suggests that end-tidal isoflurane monitoring does not improve the titration of isoflurane during general anesthesia.

This study was designed to evaluate the impact of routine end-tidal anesthetic gas monitoring on the intraoperative hemodynamic stability and early recovery profile in 253 consenting ASA physical status I-III patients undergoing elective otolaryngologic procedures with isoflurane or enflurane anesthesia. Patients were randomly assigned to one of six treatment groups: Group I, monitored high-flow isoflurane; Group II, unmonitored high-flow isoflurane; Group III, monitored low-flow isoflurane; Group IV, unmonitored low-flow isoflurane; Group V, monitored low-flow enflurane; or Group VI, unmonitored low-flow enflurane. After a standardized induction sequence, anesthesia was maintained by administering variable concentrations of isoflurane or enflurane in an air/oxygen mixture at two different total gas flow rates (0.7 L/min or 3.5 L/min, respectively). Mean arterial pressure (MAP), heart rate (HR), and end-tidal (ET) anesthetic concentrations were recorded by a computer throughout the operation. The resident anesthesiologist was instructed to maintain an adequate "depth of anesthesia" by varying the administration of isoflurane (Groups I-IV) or enflurane (Groups V and VI) with or without end-tidal gas monitoring. Intraoperative hemodynamic stability was assessed in each patient and reported as the average error from the preincisional (baseline) MAP, average absolute error from the baseline MAP, coefficients of variation for HR, systolic, diastolic, and MAP values, and ET anesthetic concentrations. Recovery times from discontinuation of the volatile drug until awakening, following commands, and postanesthesia care unit (PACU) discharge were recorded. The six study groups had similar intraoperative MAP and HR values, coefficients of variation, and numbers of episodes of hypertension, hypotension, tachycardia, and bradycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of acute alcohol ingestion on the left ventricular performance of nine normal subjects, mean age 25 years, were studied before and after incomplete autonomic blockade, produced by atropine, 0.04 mg/kg body weight, and propranolol, 0.2 mg/kg body weight. Left ventricular (LV) function curves (stroke volume vs. end-diastolic volume) were plotted from data generated before and after large variations in cardiac preload. Increase in preload was produced by five degrees of head-down tilt for 90 minutes; decrease in preload was produced by graduated lower body negative pressure to -40 mmHg. After incomplete autonomic blockade, the negative inotropic effects of acute alcohol ingestion were minimal but significant and manifest by the reduction in mean velocity of circumferential fiber shortening (p less than 0.05). Studies during wide variations in preload confirmed the importance of maintaining central blood volume after alcohol ingestion. Lower body negative pressure after both incomplete autonomic blockade and alcohol produced a further deterioration in mean velocity of circumferential fiber shortening (p less than 0.05).

Echocardiographic (E) assessment of left ventricular response to increases (I) and decreases (D) in preload of 9 volunteer male subjects (mean age 25 +/- 2.0 years) was made during both control (C) and cardiac blocked (B) conditions. Cardiac autonomic blockade was produced by intravenous administration of atropine (0.04 mg/kg) and propranolol (0.2 mg/kg), while I was produced by 5 degrees head-down tilt (T) for 90 min and D by lower body negative pressure to -40 Torr. Increases in resting heart rate of 44% and diastolic blood pressure of 13% occurred after B, (P less than 0.05). During C, the alterations in preload produced mean changes in end-diastolic volume (EDV) ranging from 135 +/- 10 cm3 for I to 96 +/- 9.1 cm3 for D. Changes in stroke volume during condition C were significantly related to changes in EDV during preload alterations and conformed to a normal LV function curve and were described by SV = 0.6 EDV + 4.5 cm3 (r = 0.85; P less than 0.001). Similarly during B, SV = 0.43 EDV + 5.8 cm3 (r = 0.75; P less than 0.001). Comparison of the LV function curves produced during C and B showed that both slope of regression and r were significantly different (P less than 0.01). These data indicate that cardiac autonomic blockade produces a downward shift in the LV function curve indicating a depression in myocardial contractility. In addition, the data indicate that changes observed in LV function during wide variations in preload are independent of autonomic nervous system influences and are independent of the intrinsic heart rate.