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PubMed1987

Tidal volume changes due to the interaction of anesthesia machine and anesthesia ventilator.

Tidal volume (VT) delivered by mechanical ventilation during anesthesia may be influenced by factors related not only to the patient and the breathing circuit, but also to the interaction between the anesthesia machine and the anesthesia ventilator. To characterize this interaction, we studied in a test lung the effect of fresh-gas-flow (FGF) (0.25, 2.5, 5, and 10 L/min), inspiratory-to-expiratory time ratio (I:E) (1:1, 1:2, and 1:3), and ventilatory frequency (8, 12, and 16 breaths/min) at fixed ventilator bellows excursions of 300, 600, and 900 ml. The influence of these variables was also estimated mathematically for a pediatric situation: a bellows excursion of 50 ml at 20 and 30 breaths/min. Each variable studied was associated with an increase, sometimes dramatic, in the delivered VT compared with that which was set. The VT augmentation was greatest at the highest FGF rate, largest I:E ratio, and slowest respiratory rate. Because the magnitude of the augmentation is independent of the VT setting, the percent increase is much larger for pediatric settings. For example, with VT set at 50 ml, delivered VT ranged from 71 ml (FGF 2.5 L/min, I:E 1:3, and 30 breaths/min) to 300 ml (FGF 10 L/min, I:E 1:1, and 20 breaths/min). Thus it is possible in the pediatric situation to increase the delivered VT by sixfold without changing the ventilator bellows excursion. The magnitude of the changes was slightly larger for the VT settings for adult patients because of the slower respiratory rate. This VT augmentation can be predicted by the product of FGF (ml/s) and inspiratory time (seconds).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1986

An anesthesia information system for monitoring and record keeping during surgical anesthesia.

We have developed an anesthesia information system (AIS) that supports the anesthesiologist in monitoring and recording during a surgical operation. In development of the system, emphasis was placed on providing an anesthesiologist-computer interface that can be adapted to typical situations during anesthesia and to individual user behavior. One main feature of this interface is the integration of the input and output of information. The only device for interaction between the anesthesiologist and the AIS is a touch-sensitive, high-resolution color display screen. The anesthesiologist enters information by touching virtual function keys displayed on the screen. A data window displays all data generated over time, such as automatically recorded vital signs, including blood pressure, heart rate, and rectal and esophageal temperatures, and manually entered variables, such as administered drugs, and ventilator settings. The information gathered by the AIS is presented on the cathode ray tube in several pages. A main distributor page gives an overall view of the content of every work page. A one-page record of the anesthesia is automatically plotted on a multicolor digital plotter during the operation. An example of the use of the AIS is presented from a field test of the system during which it was evaluated in the operating room without interfering with the ongoing operation. Medical staff who used the AIS imitated the anesthesiologist's recording and information search behavior but did not have responsibility for the conduct of the anesthetic.

Anesthesia Department, Hospital↗
PubMed2000

Unilateral bupivacaine spinal anesthesia for outpatient knee arthroscopy. Italian Study Group on Unilateral Spinal Anesthesia.

PURPOSE: To compare unilateral and conventional bilateral bupivacaine spinal block in outpatients undergoing knee arthroscopy. METHODS: One hundred healthy, premedicated patients randomly received conventional bilateral (n = 50) or unilateral (n = 50) spinal anesthesia with 8 mg hyperbaric bupivacaine 0.5%. A lateral decubitus position after spinal injection was maintained in unilateral group for 15 min. Times from spinal injection to readiness for surgery, block resolution, and home discharge were recorded. RESULTS: Three patients in each group were excluded due to failed block. Readiness for surgery required 13 min (5 - 25 min) with bilateral and 16 min (15 - 30) with unilateral spinal block (P = 0.0005). Sensory and motor blocks on the operated limb were T9 (T12 - T2) with a Bromage score 0/1/2/3: 0/2/0/45 in the unilateral group and T7 (T12 - T1) with Bromage score 0/1/2/3: 4/1/6/36 with bilateral block(P = 0.026 and P = 0.016, respectively). Vasopressor was required only in five bilateral patients (P = 0.02). Two segment regression of sensory level and home discharge required 81+/-25 min and 281+/-83 min with bilateral block, and 99+/-28 min and 264+/-95 min with unilateral block (P = 0.002 and P = 0.90, respectively). CONCLUSION: Seeking unilateral distribution of spinal anesthesia provided more profound and longer lasting block in the operated limb, less cardiovascular effects, and similar home discharge compared with bilateral spinal anesthesia, with only a slight delay in preparation time.

Adult↗
PubMed1998

[Tumescence local anesthesia. Improvement of local anesthesia methods for surgical dermatology].

The tumescent technique of local anesthesia was developed by J. Klein ten years ago to facilitate liposuction surgery. Tumescent anesthesia not only became the standard technique for liposuction, but proved to be of great value for other surgical problems in dermatology. Meanwhile, several noncosmetic uses for tumescent anesthesia were pioneered by dermatologic surgeons. This first review of the tumescent technique in German literature will focus on its specific advantages and disadvantages when applied in different fields of dermatologic surgery. Our own experience will be discussed, as well as future developments.

Anesthesia, Local↗
PubMedDate not supplied

Effects of subtenon anesthesia combined with general anesthesia on perioperative analgesic requirements in pediatric strabismus surgery.

BACKGROUND AND OBJECTIVES: Pediatric strabismus surgery leads to undesirable intraoperative and postoperative side effects that include pain, postoperative nausea and vomiting (PONV), and oculocardiac reflex (OCR). We hypothesized that subtenon anesthesia performed before the start of surgery and combined with general intravenous anesthesia would reduce these adverse effects. METHODS: Forty children (2.5 to 6 years of age, ASA status I to II) were prospectively randomized to receive either subtenon bupivacaine 0.5% or a saline injection before the beginning of surgery in a double-blind manner. Perioperative analgesic requirements, pain scores (CHEOPS scale), hemodynamics, and incidence of OCR and PONV were compared. RESULTS: Postoperative pain scores were lower (P < .001) at removal of the laryngeal mask and 30 minutes later in the bupivacaine group. Intraoperative and postoperative analgesic requirements were significantly reduced in this group (P < .01). The incidence of OCR and PONV were also significantly decreased (P < .01). Intraoperative values of blood pressure were significantly higher in the saline group at 20 minutes (P < .02). CONCLUSION: We conclude that preoperative subtenon bupivacaine 0.5% compared with a saline injection contributed to reduction of perioperative pain and undesirable side effects in pediatric strabismus surgery performed under general anesthesia.

Anesthesia, General↗
PubMed1994

Pinpoint anesthesia: a new approach to local ocular anesthesia.

Current methods of local ocular anesthesia, including retrobulbar, peribulbar, and topical anesthesia, have distinct limitations and many possible, potentially serious complications. We present a new technique that provides rapid, thorough local ocular anesthesia and eliminates these potential complications.

Anesthesia, Local↗
PubMed1986

Posterior peribulbar anesthesia: an alternative to retrobulbar anesthesia.

Posterior peribulbar anesthesia is a safe alternative to retrobulbar anesthesia for ophthalmic surgery. Because the anesthetic is deposited outside the muscle cone, the potential for intraocular or intradural injection is greatly minimized. Furthermore, intraconal hemorrhage and direct optic nerve injury is avoided. We illustrate the details of our technique for posterior peribulbar anesthesia and describe our experience in over 1,600 cases.

Anesthesia, Local↗
PubMed2002

Changes in heart rate variability in sevoflurane and nitrous oxide anesthesia: effects of respiration and depth of anesthesia.

STUDY OBJECTIVE: To quantify the effects of sevoflurane on autonomic nerve function by analyzing changes in heart rate (HR) variability in sevoflurane anesthesia; and to investigate the effects of anesthetic depth and apnea on HR variability. DESIGN: Prospective study. SETTING: Operating room (OR) of a university medical center. PATIENTS: 7 ASA physical status I and II patients scheduled for elective surgery. INTERVENTIONS: Patients were premedicated with ranitidine 150 mg. Anesthesia was induced with thiopental sodium 4 mg/kg intravenously (IV) and succinylcholine 1 mg/kg IV, and maintained with nitrous oxide (N(2)O) 67% and sevoflurane in oxygen. Patients were ventilated mechanically at a rate of 15 breaths/min. MEASUREMENTS: R-R interval of electrocardiography (ECG), electroencephalogram (EEG), noninvasive arterial blood pressure (BP), and end-tidal sevoflurane concentration were recorded. Measurements were performed 1) after patients arrived at the OR and were placed in the supine position, 2) a stable period after inhalation of 2% sevoflurane, and 3) following the appearance of an isoelectric EEG at a higher concentration of sevoflurane. At times 2) and 3), data were recorded during mechanical ventilation and during apnea. MAIN RESULTS: There were decreases in both the low-frequency (LF; 0.04 to 0.15 Hz) and high-frequency (HF; 0.15 to 0.4 Hz) components of HR variability during anesthesia compared with the awake state. HF decreased during apnea at 2% sevoflurane, but LF did not change. Neither LF nor HF changed in response to the absence or presence of respiration during isoelectric EEG. CONCLUSIONS: Autonomic nerve activity was attenuated by sevoflurane. Parasympathetic input to the heart by respiration was markedly suppressed following the appearance of isoelectric EEG.

Adult↗
PubMed2002

A combination of intrathecal morphine and remifentanil anesthesia for fast-track cardiac anesthesia and surgery.

OBJECTIVE: To determine if the combined remifentanil and intrathecal morphine (RITM) anesthetic technique facilitates early extubation in patients undergoing coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, randomized, controlled clinical trial. SETTING: Referral center for cardiothoracic surgery at a university hospital. PARTICIPANTS: Patients (n = 24) undergoing first-time elective CABG surgery. INTERVENTIONS: Two groups represented RITM (n = 12) and fentanyl-based (controls, n = 12) anesthesia. Premedication was standardized to temazepam, 0.4 mg/kg, and anesthesia was induced with etomidate, 0.3 mg/kg, in both groups. The RITM group received remifentanil, 1 microg/kg bolus followed by 0.25 to 1 microg/kg/min infusion, and intrathecal morphine, 2 mg. The control group received fentanyl, 12 microg/kg in 3 divided doses. Anesthesia was maintained with isoflurane and pancuronium in both groups. After completion of surgery, the remifentanil infusion was stopped. Complete reversal of muscle relaxation was ensured with a nerve stimulator, and a propofol infusion, 0.5 to 3 mg/kg/h, was started in both groups. All patients were transferred to the intensive care unit (ICU) to receive standardized postoperative care. Intensivists and ICU nurses were blinded to the group assignment. Propofol infusion was stopped, and the tracheal extubation was accomplished when extubation criteria were fulfilled. MEASUREMENTS AND MAIN RESULTS: Both groups were similar with respect to demographic data and surgical characteristics. Extubation times were 156 +/- 82 minutes and 258 +/- 91 minutes in the RITM and control groups (p = 0.012). Patients in the RITM group exhibited lower visual analog scale pain scores during the first 2 hours after extubation (p < 0.04). Morphine requirements during the 24 hours after extubation were 2.5 +/- 3 mg in the RITM group and 16 +/- 11 mg in the control group (p = 0.0018). Sedation scores were lower in the RITM group during the first 3 hours after extubation (p < 0.03). Pulmonary function tests as assessed by spirometry were better in the RITM group at 6 and 12 hours after extubation (p < 0.04). There were no significant differences in PaO(2) and PaCO(2) after extubation between the 2 groups. None of the patients had episodes of apnea during the immediate 24-hour postextubation period. Two patients from the RITM group required reintubation on the second and sixth postoperative days. There were no differences in ICU and hospital length of stay between the 2 groups. CONCLUSION: Implementation of the RITM technique provided earlier tracheal extubation, decreased level of sedation, excellent analgesia, and improved spirometry in the early postoperative period. The impact of RITM on ICU and hospital length of stay and potential cost benefits require further evaluation.

Analgesics, Opioid↗
PubMed1994

Thyroid surgery using monitored anesthesia care: an alternative to general anesthesia.

Forty consecutive patients undergoing thyroid surgery under local anesthesia (LA) by a single surgeon over a 5-year period were included in this retrospective review. In all cases, the indication for LA was patient request. The study included 29 females and 11 males with an average age of 44 years (range 22-66 years). Body habitus was thin in 12.5%, average in 67.5%, and obese in 20%. Operations consisted of 21 unilateral thyroid lobectomies, 3 partial thyroidectomies, 3 subtotal thyroidectomies, and 13 total thyroidectomies. The pathology revealed benign disease in 45% and malignant disease in 55%. All procedures were performed using lidocaine and/or bupivacaine to administer a deep cervical plexus block as well as a field block. Mild additional intraoperative intravenous sedation was provided in most cases. Two patients were converted emergently to general endotracheal anesthesia because of inability to tolerate LA in one and a seizure secondary to intraarterial injection of lidocaine in the other patient. There were no instances of wound infection hemorrhage, recurrent laryngeal nerve injury, or hypoparathyroidism. In conclusion, thyroid surgery in selected patients can be performed safely using LA by experienced surgeons. If patients are carefully prepared preoperatively, LA offers a simple and reasonable alternative to general anesthesia.

Adult↗
PubMed1997

Development of a measure of patient satisfaction with monitored anesthesia care: the Iowa Satisfaction with Anesthesia Scale.

BACKGROUND: The authors describe development of the Iowa Satisfaction with Anesthesia Scale (ISAS) for monitored anesthesia care (MAC). Patients complete the self-administered written questionnaire before discharge from the hospital. The authors designed the ISAS to measure satisfaction with MAC itself, not the perioperative experience. Patients respond to eleven statements (e.g., "I felt pain") by placing a mark along a six-choice vertical response column (e.g., "Disagree moderately") below each statement. The mean of their responses to each of the 11 statements gives a single number, which is a quantitative measure of a patient's satisfaction with their MAC. METHODS: Adult, English-speaking patients completed the questionnaires following admission to a phase II postanesthesia care unit after MAC. RESULTS: Response rate for MAC was 92% (86 of 94 patients). Patients completed the questionnaire in 4.6 +/- 2.3 min. Internal consistency, Cronbach's alpha, equaled 0.80. Patients' scores were positively correlated with those predicted by their anesthesia provider (r2 = 0.23) and with responses to the question "I was satisfied with my anesthetic care" (Kendall's tau = +0.41). Scores on initial and repeat questionnaires were positively correlated (r2 = 0.74). Scores on initial questionnaires and those completed within 4.4 +/- 1.7 days postoperatively were positively correlated (r2 = 0.76). CONCLUSIONS: The authors have developed and tested an internally consistent, reliable, and valid measure of patient satisfaction with MAC.

Adult↗
PubMed2002

Changes of electroencephalographic bicoherence during isoflurane anesthesia combined with epidural anesthesia.

BACKGROUND: The authors previously reported that, during isoflurane anesthesia, electroencephalographic bicoherence values changed in a fairly restricted region of frequency versus frequency space. The aim of the current study was to clarify the relation between electroencephalographic bicoherence and the isoflurane concentration. METHODS: Thirty elective abdominal surgery patients (male and female, aged 34-77 yr, American Society of Anesthesiologists physical status I-II) were enrolled. After electroencephalogram recording with patients in an awake state, anesthesia was induced with 3 mg/kg thiopental and maintained with oxygen and isoflurane. Continuous epidural anesthesia with 80-100 mg/kg 1% lidocaine was also administered. Using software they developed, the authors continuously recorded the FP1-A1 lead of the electroencephalographic signal and expired isoflurane concentration to an IBM-PC compatible computer. After confirming the steady state of each isoflurane (end-tidal concentration at 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, and 1.5%), electroencephalographic bicoherence values were calculated. RESULTS: In a light anesthetic state, electroencephalographic bicoherence values were low (generally < or = 15.0%). At increased concentrations of isoflurane, two peaks of electroencephalographic bicoherence emerged along the diagonal line (f1=f2). The peak emerged at around 4.0 Hz and grew higher as isoflurane concentration increased until it reached a plateau (43.8 +/- 3.5%, mean +/- SD) at isoflurane 0.9%. The other peak, at about 10.0 Hz, also became significantly higher and reached a plateau (32.6 +/- 9.2%) at isoflurane 0.9%; at isoflurane 1.3%, however, this peak slightly decreased. CONCLUSION: Changes in the height of two electroencephalographic bicoherence peaks correlated well with isoflurane concentration.

Adult↗
PubMed1987

Neurological complications of dynamic reduction of Colles' fractures without anesthesia compared with traditional manipulation after local infiltration anesthesia.

To investigate whether or not injection of local anesthetic into the fracture hematoma on reduction of a Colles' fracture increases the risk of neurological complications, a prospective randomized trial was conducted. The outcome in 62 patients whose Colles' fractures were reduced in a new bone-alignment device without anesthesia was compared with that in 54 patients with Colles' fractures that were reduced manually after injection of local anesthetic. At follow-up, any symptoms and signs of nerve damage were recorded. Four cases of such damage were noted in the group treated without local anesthesia, as opposed to 14 in the group in which a local anesthetic was used. The difference is significant (p less than 0.01). The authors have previously shown that injection of local anesthetic into the hematoma of Colles' fractures increases the carpal tunnel pressure. Neurological complications after the use of local anesthesia in reducing Colles' fractures is considered to be secondary to the scarring and fibrosis caused by this increase in pressure.

Adult↗
PubMed2005

Use of a new local anesthesia--intracorpus spongiosum anesthesia--in procedures on anterior urethra.

BACKGROUND: Urologists often perform procedures on anterior urethra, which is one of the most sensitive parts in male patients. The aim of the present study was to determine the efficacy of intracorpus spongiosum anesthesia during procedures on anterior urethra in the outpatient clinic. METHODS: A dosage of 3 mL of 1% lidocaine was slowly injected into the glans penis of 51 male patients. Immediately following injection, they underwent different procedures on anterior urethra. The subjective experience of pain in the patients was assessed by questionnaire according to a pain scale. RESULTS: Forty-seven patients (92.16%, 47/51) had zero pain and four cases (7.84%) had either minor or moderate discomfort, which was limited and tolerable. The anesthetic effect is immediate and has been very satisfactory. All the procedures (mean duration, 33 min), were successfully completed under the intracorpus spongiosum anesthesia. The act of injection into the glans caused instantaneous minor pain in 45 patients (88.23%, 45/51), moderate pain in four patients and no pain in two patients. There were no serious complications with this anesthetic technique, although two cases had instantaneous trance during injection of lidocaine. CONCLUSIONS: Minor procedures on anterior urethra in an outpatient setting with intracorpus spongiosum anesthesia are generally painless, safe, simple, successful and inexpensive compared to those performed in a hospital.

Adolescent↗
PubMed2003

An animal model for surgical anesthesia and analgesia: characterization with isoflurane anesthesia and remifentanil analgesia.

UNLABELLED: With a traditional clamp test alone, quantitative evaluation of the level of surgical anesthesia/analgesia is not easy. We have developed a rabbit model that allows for repeated quantification of the varying level of surgical anesthesia/analgesia using both mechanical and electrical stimulation as simulated surgical stimuli. After tracheostomy and intravascular cannulations under isoflurane anesthesia, eight rabbits were placed on a sling that allowed for free movement of the head and extremities. The inspired isoflurane concentration was reduced from 3% to 1.5% and then to 0%. Remifentanil was then infused at 4 graded infusion rates (0.1-0.8 microg. kg(-1) x min(-1)). At each drug dose, analgesic variables were determined including the number of animals behaviorally unresponsive to clamping the forepaw (nonresponders) and threshold voltage of subcutaneous electrical stimulation (2 Hz, 5 Hz, and 50 Hz) required to evoke the head lift (HLT, pain detection/arousal threshold) and escape movement responses (EMT, pain tolerance threshold). With increasing drug doses, HLTs and EMTs at 5 Hz increased dose-dependently and most proportionately to increases in the number of nonresponders, a standard indicator of the anesthetic/analgesic level. Therefore, using the HLT and EMT at 5 Hz combined with a clamp test, this rabbit model allows for quantitative evaluation of the varying level of surgical anesthesia/analgesia. IMPLICATIONS: We have developed a rabbit model of surgical anesthesia and analgesia using both mechanical and electrical stimulation as simulated surgical stimuli, which allows for repeated, quantitative, and qualitative evaluation of the varying level of surgical anesthesia and analgesia, differentiation between sedative/hypnotic and analgesic components of drug actions, and simultaneous monitoring of all the clinically relevant physiological variables including cardiovascular and respiratory variables.

Analgesia↗
PubMed1999

[Changes in SpO2 during total intravenous anesthesia combined with propofol and SpO2 during one-lung anesthesia ventilation].

We retrospectively examined SpO2 during one-lung anesthesia (OLA). One hundred and fifty patients of ASA 1 or 2 for thoracoscopic surgery were anesthetized with propofol and fentanyl (n = 93) or pentazocine (n = 57) and mechanically ventilated with FIO2 = 0.6 in the lateral decubitus position. Twelve patients (8%) developed SpO2 < or = 95% in the first 20 minutes of OLA. It has been reported that hypoxemia during OLA occurs in 13-40% of patients under inhalation anesthesia with FIO2 = 1.0. Our results show the total intravenous anesthesia using propofol is useful to maintain SpO2 during OLA. SpO2 during OLA tended to fall in the patients for right side operation, with lower SpO2 during two-lung ventilation and higher body mass index (BMI). However BMI has never been reported as a predictor of hypoxemia during OLA. A gravity-dependent mechanism is considered to be more responsible for the dependent regional volume reduction during OLA in patients in the lateral decubitus position.

Adolescent↗
PubMed2001

[Assessment of anesthesia satisfaction using direct interviews at post-anesthesia clinic].

The authors studied 5,034 consecutive patients undergoing elective surgery. Preoperative, intraoperative, and postoperative variables were gathered and patient satisfaction was assessed using direct interviews at pre- and post-anesthesia clinic. Fifty-nine percent of the 4,717 responders showed satisfaction and 4% showed dissatisfaction with anesthesia. The most undesirable perioperative outcome was vomiting/nausea. Other undesirable outcomes include discomfort of urine catheter, sore throat, memory of extubation, postoperative pain and so on. Anesthesiologist can improve the quality of anesthesia by preoperative explanation and preventative management for undesirable perioperative outcomes.

Anesthesia↗
PubMedDate not supplied

Effect of intravenous flumazenil on reversal of the central effects of midazolam used with short-acting opioids for general anesthesia in hospitalized patients: report of a multicenter, double-blind clinical study. The Flumazenil in General Anesthesia in Hospitalized Patients Study Group I.

Midazolam, a short-acting benzodiazepine central nervous system (CNS) depressant widely used for the induction and maintenance of general anesthesia, is often supplemented with short-acting opioids for general anesthesia. Administered postoperatively, flumazenil, a specific benzodiazepine antagonist, reverses the CNS sedative effects of midazolam. In a double-blind clinical trial in hospitalized patients, flumazenil, administered postoperatively at an average intravenous dose of 0.89 mg (range: 0.4 mg to 1 mg), was more effective than placebo in reversing sedation and other residual effects of benzodiazepines in patients recovering from general anesthesia induced by midazolam (mean dose 29 mg) in conjunction with fentanyl (mean dose 0.4 mg) or sufentanil (mean dose 0.056 mg). Five minutes posttreatment, 87 (83%) of 124 flumazenil-treated patients and 6 (10%) of 60 placebo-treated patients had attained the criterion response for reversal of sedation. Of these patients, 60% in the flumazenil group, compared with 100% in the placebo group, retained their degree of alertness throughout the 3-hour observation period. Between-group differences were significant until 60 minutes posttreatment, when the effect of the benzodiazepines had spontaneously waned in the placebo group. The Physician's Global Efficacy Rating, providing an overall measure of efficacy 5 minutes after test drug administration, was good or excellent for 86% of the flumazenil-treated patients, as compared with 7% of the placebo-treated patients evaluated. Measurements of psychomotor function and memory also showed significant between-group differences. Flumazenil, compared with placebo, was not associated with a substantially greater frequency of operative-site pain. These results demonstrate that the efficacy and safety of flumazenil were not compromised by the addition of a short-acting opioid to the anesthetic regimen.

Adolescent↗