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PubMed2000

Changes in cerebral blood volume and cerebral oxygenation during periodic breathing in term infants.

The present study is an analysis of changes in cerebral oxygenation and cerebral blood volume (CBV) during periodic breathing in healthy term infants by means of near infrared spectroscopy (NIRS). Polygraphy included electrocardiogram, electrooculogram, heart rate, oxygen saturation, side stream capnography, two respiratory effort sensors, a movement sensor, and NIRS. During periodic breathing analysis of behaviour of total haemoglobin (cHbtot), deltaCBV, the haemoglobin oxygenation index (cHbD), and cytochrome oxidase (CytOx) was performed. In ten healthy term infants 30 cycles of periodic breathing with a mean of 10 apnoeas per cycle were analysed. Corresponding cyclical variations of cHbD appeared in 98%, cyclical variations of cHbtot appeared in 42% of all apnoeas. During phases of apnoea, a mean decrease of cHbD of -3.45 micromol/l occurred 1.75 seconds after onset of apnoea, and a mean decrease of cHbtot of -0.79 micromol/occurred 0.74 seconds after onset of apnoea. During these apnoeas, the deltaCBV was -44 microl/100 g brain. During phases of ventilation, there was an increase of cHbD and cHbtot to the pre-apnoeic levels. There was a tendency that CytOx values decreased during periodic breathing, the amount of decrease was -0.32 micromol/l. In conclusion, the present study was able to show for the first time that there is cyclical desaturation and reoxygenation of cerebral blood during periodic breathing. Cyclical changes in CBV in association with periodic apnoea occurred only in 42% of apnoea.

Blood Volume↗
PubMed2003

Preparation, premedication and surveillance.

The main end points for sedation during endoscopy are patients' satisfaction, short duration of the procedure, and safety. During the last year, attention has focused on attempting to identify the "ideal" candidate for moderate sedation/analgesia and on the importance of providing the patient with appropriate information before the procedure. The increasing pressure to perform more procedures, reduce costs, and achieve shorter patient turnaround times has affected recent approaches to sedation during endoscopy, focusing attention on alternatives to pharmacological sedation such as providing relaxing music, using small-caliber endoscopes for unsedated peroral gastroscopy, and using magnetic endoscopic imaging to increase tolerance and reduce discomfort during colonoscopy. The results, however, have not been convincing. The role of benzodiazepines was discussed in some studies, highlighting the well-known effect of midazolam on postprocedural amnesia, its pharmacological profile and tolerability after intranasal spraying in healthy volunteers, and the efficacy and safety of this route of administration as an alternative to intravenous administration in diagnostic upper gastrointestinal endoscopy. The form of sedation for gastrointestinal endoscopy that has attracted great interest over the last year is the use of intravenous propofol, either alone or with concomitant benzodiazepines or opioids. As expected in view of the drug's known pharmacological properties, the quality of sedation was better and recovery time was shorter in patients treated with propofol. However, important questions involving the narrow therapeutic range and the mode of administration of propofol (by endoscopists or nurses, or by anesthesiologists) remain open. One important aspect of sedation procedures is prevention of cardiopulmonary complications. The use of electronic monitoring techniques, with a pulse oximeter, has been recommended as a standard procedure during digestive endoscopy; however, pulse oximetry no longer reflects the normal ventilatory functions and does not detect episodes of severe CO2 retention. CO2 monitoring by transcutaneous measurement - or better, by capnography - appears to be useful, as an alternative to pulse oximetry, as a measure of hypoventilation, and for detecting potentially important abnormalities in respiratory activity in patients undergoing sedation for gastrointestinal endoscopy. With regard to preparation for endoscopic procedures, several "ideal" formulas for bowel preparation have been presented. These include the use of sodium phosphate compounds as an alternative to polyethylene glycol electrolyte lavage solutions (PEG-ELS); however, the results so far have been conflicting. The best and most cost-effective bowel cleansing procedure for colonoscopy and sigmoidoscopy has yet to be established.

Anesthesia Recovery Period↗
PubMed2003

Safety of nonanesthetist sedation with propofol for outpatient colonoscopy and esophagogastroduodenoscopy.

BACKGROUND AND STUDY AIMS: In our endoscopy service, nonanesthetists administered propofol sedation has been used in more than 8000 procedures during the past 3 years. This study prospectively assessed the safety of propofol sedation in outpatient colonoscopy and esophagogastroduodenoscopy (EGD). PATIENTS AND METHODS: A total of 300 consecutive outpatients (mean age 53, range 14-94) were enrolled in the study (139 colonoscopies, 161 EGDs). After an initial dose of 0.5 mg/kg (ASA I-II and age </=70) or 0.25 mg/kg (ASA >III or age >70 years), propofol was titrated in 10 mg boluses to a steady state of sedation by the endoscopy nurse under the endoscopist's supervision. Colonoscopy patients also received 25 mg pethidine (meperidine) and 20 mg butylscopolamine, whereas EGDs were performed with propofol sedation alone, without topical pharyngeal anesthesia. In addition to standard monitoring with pulse oximetry and automated sphygmomanometry, patients were also observed with sidestream capnography or measurement of electrocardiographic impedance changes, providing real-time graphic assessment of respiratory activity. All patients were given oxygen 2 L/min by nasal cannula during the entire procedure. RESULTS: Mean dosages of 157 mg (range 70-340) and 180 mg (60-400) propofol were administered for colonoscopy and EGD procedures, respectively. No episodes of apnea occurred. The oxygen saturation fell below 90 % for short periods of time in 11 patients (3.7 %). Three patients required a temporary increase in oxygen delivery. No assisted ventilation was necessary. In 22 patients (7.3 %), the mean blood pressure temporarily decreased below 50 mmHg. Two patients received a 500-ml infusion of normal saline. CONCLUSIONS: Propofol can be safely administered for sedation during colonoscopy and esophagogastroduodenoscopy by nonanesthetists who are familiar with the pharmacological properties and use of this drug.

Adolescent↗
PubMed2004

[MRI of ventilated neonates and infants: respiratory pressure as trigger signal].

INTRODUCTION: Motivated by the difficulties often encountered in the setup of respiratory trigger in MR imaging of mechanical ventilated pediatric patients, a simplified approach in terms of time and reliability was sought. METHOD: With the help of a male-to-male Luer-Lock adapter in combination with a 3-way adapter the tube of the respiratory compensation below was fixed to the output channel for capnography of the airway filter. Ten patients (age 4 months to 6 years) were tested with spin echo imaging and either respiration compensation (T1-weighted imaging) or respiratory triggered (T2-weighted imaging). RESULTS: A clear trigger signal was achieved in all cases. No negative influence on the quality or security of the mechanical ventilation of the patients was observed. SUMMARY: The proposed adapter is safe, efficient and fast to install in patients undergoing MR imaging in general anaesthesia.

Age Factors↗
PubMed2005

Preparation, premedication, and surveillance.

In the year since the last review, continuing pressure on endoscopy suites to improve efficiency and reduce costs without compromising patient care has led to growing interest in alternatives to pharmacological sedation and in the use of short-acting sedatives. Relaxation music, acupuncture, and the use of small-caliber endoscopes for unsedated peroral gastroscopy have therefore been suggested as ways of increasing tolerance and reducing discomfort. With regard to ultrathin and superthin endoscopes, the results are interesting, but further data from controlled trials and in studies including larger numbers of patients are still needed. The form of sedation for gastrointestinal endoscopy that has attracted greatest interest over the last year is the use by nonanesthetists of intravenous propofol, administered either alone at standard doses to achieve deep sedation, or at lower doses combined with benzodiazepines and opioids to achieve moderate sedation/analgesia. In comparison with benzodiazepines/opioids, the results were in favor of propofol: the mean time to sedation was shorter and the depth of sedation was greater. In addition, patients receiving propofol reached full recovery earlier and were discharged sooner. However, in the survey of patient satisfaction at discharge, it was found that the sedation methods did not have a significant impact on overall patient satisfaction. Some important issues concerning the narrow therapeutic range of propofol and the need for adequate training of endoscopists to deal with any problems related to deep sedation are still open - despite the growing amount of data suggesting that the drug is safe even when administered by registered nurses, an approach that is possibly more cost-effective than delivery by gastroenterologists or anesthetists. The morbidity and mortality associated with cardiopulmonary complications continue to be a significant concern during gastrointestinal endoscopy. Professional societies and national expert peer groups have issued practice guidelines for sedation and analgesia that call for continuous monitoring of the patient's hemodynamic and ventilatory status and consciousness. Direct observation is facilitated by electronic devices (pulse oximetry, capnography), directly indicating the patient's ventilatory status and the depth of sedation. Recently, it has been proposed that the bispectral index (BIS), an electroencephalography-based technique, can be used to monitor the depth of sedation during gastrointestinal endoscopy. However, the results of a recent study cast some doubt on the usefulness of the BIS, in its current version, for titrating boluses of propofol to an adequate level of sedation. Further data therefore appear to be needed to assess whether or not BIS values can help avoid unnecessary propofol dosage and can replace continuous assessment of the ventilatory effort.

Procedural Sedation↗
PubMedDate not supplied

[Propofol for sedation in pediatric magnetic resonance imaging investigations].

BACKGROUND: Magnetic Resonance Imaging requires immobilisation of the patients without excitement due to acoustic irritation. During childhood this is hardly to guarantee without anaesthesia or sedation. The problem is the magnetic field strength, which interferes with the monitoring devices and the anaesthesia machines interrupting the function and can produce thermal injury, but additionally the tools will cause image degradation. PATIENT AND METHOD: MR Imaging was done in 46 children with a mean age of 50.9 months (0.06 to 129) in a sedation with propofol during spontaneous breathing. The induction dose of propofol was 3.0 mg/kg bodyweight and the repetition dose was 1.0 mg/kg. During the radiological examination and the time of emergence the children were monitored with a MRI-compatible fiberoptic pulseoximeter (NONIN), a capnography by naso-pharyngeal canula (OHMEDA) and a noninvasive blood pressure oscillometer (CRITICON). The monitors were located outside the 0.5 Tesla area and were connected to the patient via extension tubing. Additionally there was a clinical observation by a present anaesthesiologist. RESULTS: In all children the investigation has been realized without any problem. Haemodynamics, ventilation and oxygenation have been in a normal range. Only 2 of the 186 sequences had to be repeated. After a mean time of investigation of 29 minutes (10 to 55) the emergence time until purposeful reaction was 7.7 minutes (5 to 20) and until full orientation was 13.4 minutes (5 to 30). CONCLUSIONS: This regime of sedation for children undergoing Magnetic Resonance Imaging is safe and suitable independent of age: there is a good control of vital functions, a minimum of side effects and a fine recovery characteristic with short times of emergence.

Anesthetics, Intravenous↗
PubMed2001

Intraoperative contrast echocardiography with intravenous optison does not cause hemodynamic changes during cardiac surgery.

BACKGROUND: The echocardiographic contrast agent Optison may be useful in patients undergoing cardiac surgery. This study investigates its effects on hemodynamics, cardiac performance, and oxygenation in this group of patients. METHODS: Parameters of hemodynamic stability, cardiac performance, and oxygenation were measured in 57 patients by transesophageal echocardiography, electrocardiography, invasive arterial blood pressure and central venous pressure monitoring, capnography, pulsoximetry, and pulmonary artery catheter before and 5 and 10 minutes after an intravenous bolus of 0.3 mL of Optison. RESULTS: No statistically significant differences in ST-segment changes, heart rate, arterial and central venous pressure, peripheral oxygen saturation, cardiac index, left ventricular ejection fraction, and regional wall motion were seen 5 and 10 minutes after injection of Optison compared with baseline parameters. CONCLUSIONS: Optison did not cause clinically important changes in parameters of hemodynamic stability, cardiac performance, and oxygenation in our patients. The intraoperative use of intravenous Optison appears to be safe in patients undergoing cardiac surgery, including in the use of cardiopulmonary bypass.

Adult↗
PubMed2001

The relation between hyperventilation and pediatric syncope.

OBJECTIVE: The objective was to evaluate prospectively the role of hyperventilation in the development of neurocardiogenic syncope in children during head-upright tilt testing (HUTT). STUDY DESIGN: Tilt testing was performed in 34 children (mean age 10.6 years) with clinical suspicion of syncope. Respiratory rate and end-tidal carbon dioxide pressure were continuously monitored during HUTT. RESULTS: Tilt test was negative in 12 cases; 3 (25%) patients of this group exhibited hyperventilation any time during the test. In the remaining 22 cases the HUTT was positive, and 15 (68.2%) patients of this group exhibited hyperventilation at the onset of clinical symptoms and during syncope. In the positive HUTT group, the mean time elapsed from the tilt to the onset of syncope and the mean time elapsed from the onset of clinical symptoms to syncope (latency time) were significantly longer for patients who hyperventilated than for those who did not hyperventilate, (21.8 vs 11.5 minutes) (P =.002) and (78 vs 51 seconds) (P =.04), respectively. CONCLUSIONS: Spontaneous hyperventilation could play a relevant role in the pathophysiology of pediatric neurocardiogenic syncope, and it could point out a specific subtype of response to orthostatic stress in susceptible patients. We suggest the inclusion of capnography in tilt-test protocols could improve the assessment of syncope in children.

Adolescent↗
PubMedDate not supplied

Evaluation of an electronic esophageal detector device in patients with morbid obesity and pulmonary failure.

OBJECTIVE: Undetected esophageal intubation can result in permanent injury or death. Clinical confirmation of tube location may be misleading. Adjunctive methods should be used to supplement clinical judgment. Unfortunately, end-tidal carbon dioxide may misidentify properly placed tracheal tubes in low perfusion situations, while esophageal detector devices (EDDs) may misidentify properly placed tracheal tubes in situations where little airway dead space exists (morbid obesity, pulmonary failure). This study evaluated a modified EDD (the electronic esophageal detector device, or EEDD) designed to eliminate the problem of misidentified tracheal intubations. METHODS: Intubated morbidly obese or pulmonary failure patients were eligible for study entry. All endotracheal tubes (ETTs) were confirmed to be tracheal by waveform capnography and clinical judgment prior to study entry. Following consent, all patients were attached to the EEDD and a "measurement" was made to determine the "location" of their ETTs. Probability of misidentifying a tracheal intubation in these high-risk populations was calculated using a log-normal distribution method. RESULTS: Twenty-seven morbidly obese patients and 37 pulmonary failure patients were entered. The EEDD correctly identified all tracheal intubations in these patients, giving a false-negative rate of zero. The probability of misidentifying a tracheal intubation in the combined group was 0.06%. CONCLUSION: This study demonstrates that the EEDD reliably identifies tracheal intubations in situations where standard EDDs may fail. However, future studies must determine the reliability of this device for identification of esophageal intubations and the reliability of this device in the less controlled emergency department and prehospital settings.

Equipment Design↗
PubMed2002

Randomized comparison of conventional carbon dioxide insufflation and abdominal wall lifting for laparoscopic cholecystectomy.

BACKGROUND: Gasless laparoscopy using abdominal wall lifting (AWL) has been developed in an attempt to avoid the adverse effects of carbon dioxide pneumoperitoneum that may occur in conventional laparoscopy. However, lifting has been criticized for its poor operative space and surgical invasiveness. This study compared the AWL method with conventional CO2 pneumoperitoneum for laparoscopic cholecystectomy with respect to operation performance, postoperative course, and stress response. PATIENTS AND METHODS: During a 6-month period, 95 patients with symptomatic gallstones were randomly assigned to receive laparoscopic cholecystectomy with conventional CO2 pneumoperitoneum (CO2 group; N = 47) or the AWL method (AWL group; N = 48). Operative results and operative time were recorded. Cardiopulmonary functions were assessed, and arterial blood gases were analyzed during surgery. Urinary cortisol, vanillylmandelic acid, metanephrines, and nitrogen loss; serum complement 3, C-reactive protein, and interleukin-6; postoperative pain; and the presence of nausea and vomiting were assessed for 48 hours after surgery. Postoperative time to recovery of flatus, tolerance of a full oral diet, and full activity were also determined. RESULTS: Only three significant differences were found. First, intraoperative ventilatory function deteriorated significantly less in the AWL group. Second, arterial blood gas determinations and capnography showed a greater decrease in intraoperative arterial pH and compliance with CO2 retention and an increase in peak airway pressure in the CO2 group (P < 0.05), reflecting poorer ventilatory performance. Third, preparation time and total operating time were significantly greater with the AWL method (P < 0.05). CONCLUSIONS: Although AWL required a longer operation time, our results suggest that the technique may still have value in high-risk patients with cardiorespiratory diseases.

Carbon Dioxide↗
PubMed1975

The effect of anaesthesia and intermittent positive pressure ventilation with different frequencies on the anatomical and alveolar deadspace.

Deadspace was measured in nine healthy subjects in the supine position, premedicated but awake and breathing spontaneously at a rate of 12 b.p.m. and subsequently under anaesthesia with artificial ventilation with frequencies of 12 and 24 b.p.m. The minute volume was kept at a relatively constant value. The physiological deadspace was calculated using the Bohr equation and the division into anatomical and alveolar deadspace was made with the aid of capnography. Physiological deadspace was increased by anaesthesia and IPPV, mainly as a consequence of increased rebreathing in the apparatus deadspace. There was no significant change in the anatomical deadspace. Thus, the expected reduction in deadspace brought about by endotracheal intubation was nullified by an increase in the anatomical deadspace distal to the carina. The VDanat/VT ratio remained constant on changing the respiratory frequency. A significant alveolar deadspace was measured during spontaneous breathing. This was unchanged by the induction of anaesthesia and the institution of artifical ventilation. On changing the frequency, the VDalv/VT ratio remained constant. It is concluded that both the anatomical and the alveolar deadspaces increasing with increasing tidal volume, but are unaffected by the breathing rate.

Adult↗
PubMed1997

Effect of incremental doses of sevoflurane on cerebral pressure autoregulation in humans.

We have examined cerebral pressure autoregulation while awake, and during 0.5 and 1.5 MAC of sevoflurane anaesthesia in 10 patients undergoing non-intracranial neurosurgical procedures. All patients received a standardized anaesthetic comprising premedication with temazepam 20 mg orally, a sleep dose of propofol, fentanyl 1 microgram kg-1 and vecuronium 0.1 mg kg-1. After tracheal intubation, the lungs were ventilated with a mixture of air and oxygen to mild hypocapnia. Routine monitors included ECG, continuous and intermittent non-invasive arterial pressure, pulse oximetry and end-tidal capnography. In addition, blood flow velocity (vmca) was measured by insonating the middle cerebral artery transtemporally using a 2-MHz transcranial Doppler probe. Cerebral pressure autoregulation was tested by increasing mean arterial pressure (MAP) by approximately 20 mm Hg using an infusion of phenylephrine and simultaneously recording vmca. The index of autoregulation (IOR) during each period of the study, calculated as the ratio of percentage change in estimated cerebral vascular resistance (CVRe = MAP/vmca) to percentage change in MAP, was compared using ANOVA. vmca during 0.5 and 1.5 MAC of sevoflurane anaesthesia was significantly lower than that while awake (mean 79 (SD 24), 54 (15) and 51 (12) cm s-1, respectively; P < 0.05). There was no significant change in vmca with the increase in MAP while awake, or during 0.5 or 1.5 MAC of sevoflurane anaesthesia and IOR was similar under the three conditions (0.82 (0.11), 0.83 (0.04) and 1.0 (0.03), respectively). We conclude that cerebral pressure autoregulation remained intact during sevoflurane anaesthesia in humans.

Adult↗
PubMed1999

The effects on resting ventilation of intravenous infusions of morphine or sameridine, a novel molecule with both local anesthetic and opioid properties.

UNLABELLED: Sameridine has both local anesthetic and partial mu-opioid receptor agonistic properties. The aim of this single-blinded, randomized, three-way cross-over study of 12 subjects was to investigate the effects on resting ventilation of two doses of sameridine: 0.15 mg/kg (S-Small) and 0.73 mg/kg (S-Large) compared with 0.10 mg/kg morphine. Each drug was infused IV over 20 min. Ventilation was measured by pneumotachography and in-line capnography, and sedation was rated by the subjects using a visual analog scale (VAS). Plasma was collected and analyzed for sameridine and morphine. At the end of drug infusion, minute ventilation (VE) and tidal volume (VT) were reduced in the S-Large group, and VE was reduced in the morphine group. End-tidal CO2 increased in both groups (P < 0.05), but respiratory rates remained unchanged. In the S-Small group, no ventilatory changes were recorded. In the S-Large group, the median sedation score was 6.8 cm with corresponding values in the morphine and S-Small groups of 3.3 and 2.5 cm, respectively. There was a relationship between the plasma concentration of sameridine and the depression of ventilation. We conclude that sameridine influences resting ventilation and that this effect is directly related to plasma concentrations of sameridine. From a ventilatory aspect, a clinical dose of sameridine with both local anesthetic and opioid properties seems safe. IMPLICATIONS: Sameridine, a molecule with both local anesthetic and analgesic properties, impaired resting ventilation after a large IV dose (0.73 mg/kg), more so than 0.10 mg/kg IV morphine. A clinical dose of sameridine (0.15 mg/kg) did not have any effects on ventilation.

Adult↗
PubMed1999

Ventilatory responses to acute and sustained hypoxia during sevoflurane anesthesia in women.

UNLABELLED: We investigated the isocapnic hypoxic (i.e., pulse oximetry monitored arterial saturations 70%-75%) ventilatory response (HVR) for 20 min in the awake state and during sevoflurane anesthesia at an end-tidal concentration of 1.6% in eight healthy (ASA physical status I) women. Our aims were to determine if a prolonged isocapnic hypoxic period during sevoflurane anesthesia showed a biphasic response pattern (i.e., an initial acute HVR followed by a decline to a lowered sustained HVR) and, if so, to quantify to what extent the acute and sustained HVRs were depressed by anesthesia. The study was conducted before laparoscopic gynecological surgery. Pneumotachography and in-line infrared capnography were used. The pattern of awake biphasic HVR was maintained during anesthesia but was depressed during both the acute and the sustained phases by 60% and 70%, respectively. Further, HVR during anesthesia was accomplished by an increase in respiratory rate, in contrast to an increase in tidal volume in the awake state. In conclusion, sevoflurane anesthesia at 1.6% depresses HVR in women, but the biphasic response is maintained. IMPLICATIONS: Acute and sustained hypoxic ventilatory responses were investigated in eight women before and during sevoflurane anesthesia. A biphasic ventilatory response was persistent but blunted during anesthesia.

Adult↗
PubMed2001

The effects on hypercarbic ventilatory response of sameridine compared to morphine and placebo.

Sameridine, a novel molecule, has both local anesthetic and partial mu-opioid receptor properties. The aim of this single, blinded, randomized, four-way cross-over study was to investigate the hypercarbic ventilatory response (HCVR) in 12 healthy volunteers. A 20-min IV infusion of two doses of sameridine 0.15 mg/kg (S-Small) and 0.73 mg/kg (S-Large) were compared with 0.10 mg/kg of morphine and placebo. Ventilation was studied repeatedly for 2 h by pneumotachography and inline capnography. The hypercarbic ventilatory response was measured after addition of 4% CO(2) to inspired air until steady state. A visual analog scale followed sedation. After drug infusion there was a significant rightward shift (on average 4.5 mm Hg) of the ventilatory response curve (HCVR = Delta VE/Delta ETCO(2)) in the S-Large group. There were no changes of HCVR in the other groups. On a molar basis, the S-Large dose was 6.5 times the morphine dose, and such a dose would have been expected to cause a 12 mm Hg rightward shift. This discrepancy in effect is most likely a result of the partial mu-agonist effect of sameridine. Sedation was most pronounced after S-Large and morphine infusions. The authors concluded that a large IV dose of sameridine depressed the hypercarbic ventilatory response, whereas a smaller, clinical dose did not.

Analgesics, Opioid↗
PubMed2003

Hypercarbic and hypoxic ventilatory responses after intrathecal administration of bupivacaine and sameridine.

Sameridine is a new compound with both local anesthetic and opioid properties (partial micro -opioid receptor agonist). It was intended for intrathecal administration to provide anesthesia for surgery and extended postoperative analgesia. In this double-blinded pharmacodynamic study with a two-parallel-group design, we investigated, during a 24-h period, the effects of intrathecal sameridine and bupivacaine on ventilation at rest and at ventilatory challenges during hypercarbia and hypoxia. Twenty-four healthy volunteers received either 25 mg of sameridine or 15 mg of bupivacaine intrathecally. Ventilation was measured by pneumotachography and in-line capnography. Sedation was rated by a visual analog scale. Segmental spread and development of motor and sensory block were similar in both groups. There was a decrease in tidal volume 2.5 to 6 h after injection in the bupivacaine group. This was seen only at 4 h in the sameridine group. There were no other major ventilatory differences between sameridine and bupivacaine during resting ventilation. Hypercarbic (tidal volume, mean inspiratory flow) and hypoxic (mean inspiratory flow) ventilatory responses were slightly decreased in the sameridine group, but not in the bupivacaine group. We conclude that intrathecal administration of sameridine or bupivacaine in healthy volunteers produces similar, minor effects on ventilatory responses over a 24-h observation period.

Adult↗
PubMed1988

Energy expenditure and fluid and electrolyte requirements in anesthetized infants and children.

In 31 infants and children (body weights ranging from 3.8 to 25 kg), indirect calorimetry was used for the calculation of energy needs (E, kcal/h), fluid volume (FV, ml/h) and electrolyte requirements (sodium, Na+, and potassium, K+, mmol/liter per hour) during halothane anesthesia. The children were spontaneously breathing and undergoing minor lower abdominal or orthopedic surgery. A nonrebreathing anesthesia circuit was used, and gas concentrations were measured by a mass spectrometer. For the evaluation of ventilation during periods of measurements, pneumotachography and in-line capnography were used. Energy expenditure was related to weight and followed the regression equation E = 1.5 X kg + 5.2; r = 0.96. The energy needs were converted to fluid volumes according to the water requirements for heat production, which resulted in the following relationship between FV and weight: FV = 2.4 X kg + 8.6; r = 0.96. The energy expenditure was up to 50% lower than in previous reports. Extrapolations of energy needs from awake values are inappropriate to use during halothane anesthesia. Because of the low energy expenditure during anesthesia, requirements of sodium and potassium were up to 50% lower than those based on previous standards.

Anesthesia↗
PubMed1989

Prevention of intraoperative anesthesia accidents and related severe injury through safety monitoring.

Among 1,001,000 ASA Physical Status I and II patients (a subset of the 1,329,000 anesthetics administered from 1976 through mid-1988 in the nine component hospitals of the Harvard Department of Anaesthesia), there were 11 major intraoperative accidents solely attributable to anesthesia (five deaths, four cases of permanent CNS damage, and two cardiac arrests with eventual recovery) among the 70 cases reported to the insurance carrier. Review of these accidents revealed that unrecognized hypoventilation was the most common cause (seven cases). These seven accidents and one other due to discontinuation of inspired oxygen in all likelihood would have been prevented by appropriate response to earlier warnings generated by the "safety monitoring" principles mandated by the Harvard minimal monitoring standards. Analysis suggests capnography (although not mandated) would be the best monitor of ventilation. An important associated issue was the apparent inadequacy of supervision of residents and C.R.N.A.s. The eight preventable accidents represent 88% of the projected insurance payout. Only one accident occurred after the 1985 adoption of the standards (in the month following their implementation). From that time through mid-1988, there have been 319,000 anesthetics without a major preventable intraoperative injury. Although not statistically significant, the accident rate in the target population of healthy people is reduced more than threefold. This and the case analyses support the contention that nearly all the inevitable mishaps (technical or from errors in judgement) that occur during anesthesia can be identified through safety monitoring early enough to prevent most major patient injuries. This improved clinical outcome should lessen the medical-legal and malpractice insurance burdens of anesthesiologists.

Accident Prevention↗