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At least 703 records · Page 39Linked to original sources
PubMed1998

Injection pain with propofol: the effectiveness of thiopentone on induction.

One hundred and twenty-seven children aged 3-6 years were allocated to four groups. All of them received venous cannulation on the dorsum of the hand. On induction, the group L1, L2 and L3 patients received propofol 3 mg/kg mixed with lignocaine 0.15 mg/kg, 0.3 mg/kg, 0.6 mg/kg, respectively. The group T patients received thiopentone 3 mg/kg, then propofol 1.5 mg/kg mixed with lignocaine 0.075 mg/kg. Pain on injection was categorized into two-assessment items (facial expression and limbs withdrawal). The facial expression category were subdivided into none, mild (knit of brows), moderate (grimace), and severe (crying). The withdrawal of limbs was categorized into none, mild (withdrawal of hand), moderate (withdrawal of fore-arm and arm), severe (withdrawal of arm and twisting of body). Patients were monitored using an electrocardiogram, pulse oximeter, autonomic noninvasive blood pressure measuring device and capnography. The patient characteristics did not differ significantly among the four groups. Pain on injection was significantly more frequent in the group L1 patients (81%) compared with the group T (27%) patients. Increasing lignocaine dose reduced the incidence of pain graded as "moderate" or "severe" though there was no significant difference. The incidences of excitatory effect on propofol injection were reduced with increasing lignocaine dose and prior administration of thiopentone but there were no obviously differences among groups. We concluded that thiopentone reduced injection pain on propofol and should be recommended.

Anesthetics, Intravenous↗
PubMed1998

[Review on the use of CO2 in laparoscopy surgery].

Laparoscopic surgery is one of the treatment modalities available to urologists, who must be familiar with the concepts of the physiology of CO2 and its clinical consequences. CO2 is absorbed during insufflation, leading to hypercapnia, reaching a steady-state from the 20th minute. The insufflation pressure must be between 10 and 14 mmHg. Intraoperative surveillance is based on oxygen saturation (pulse oximeter) and capnography, which measures the CO2 concentration of expired air. The causes of hypercapnia must be prevented: untimely recovery, retroperitoneal dissection, excessive intra-abdominal pressure. If hypercapnia occurs, the patient must be exsufflated and the operation should be resumed after a certain interval. The specific complications of laparoscopy (gas embolism, arrhythmias, pneumothorax) can be avoided by respecting the rules of security and by maintaining surveillance during recovery. The pain due to diaphragmatic peritoneal irritation can also be decreased by complete exsufflation.

Carbon Dioxide↗
PubMed1999

Eltanolone (5-beta-pregnanolone) does not trigger, and attenuates halothane triggering of, malignant hyperthermia in malignant hyperthermia susceptible swine.

Eltanolone is the lipid emulsion formulation, for intravenous use, of the steroid anaesthetic 5-beta-pregnanolone. We have screened this agent in malignant hyperthermia susceptible (MHS) Landrace swine to assess its potential to trigger the Malignant Hyperthermia (MH) syndrome in MHS subjects or to influence halothane triggering of MH in such patients. Administered in anaesthetic concentration, eltanolone did not trigger the MH syndrome in MHS swine. When co-administered in low dosage with halothane, the drug prevented initiation of the MH syndrome in four of eight pigs and attenuated its progress in the remainder.

Anesthetics, Inhalation↗
PubMed1996

Measurement of pulmonary CO2 elimination must exclude inspired CO2 measured at the capnometer sampling site.

OBJECTIVE: The pulmonary elimination of the volume of CO2 per breath (VCO2/br, integration of product of airway flow (V) and PCO2 over a single breath) is a sensitive monitor of cardio-pulmonary function and tissue metabolism. Negligible inspired PCO2 results when the capnometry sampling site (SS) is positioned at the entry of the inspiratory limb to the airway circuit. In this study, we test the hypothesis that moving SS lungward will result in significant inspired CO2 (VCO2[I]), that needs to be excluded from VCO2/br. METHODS: We ventilated a mechanical lung simulator with tidal volume (VT) of 800 mL at 10 breaths/min. CO2 production, generated by burning butane in a separate chamber, was delivered to the lung. Airway V and PCO2 were measured (Capnomac Ultima, Datex), digitized (100 Hz for 60 s), and stored by microcomputer. Then, computer algorithms corrected for phase differences between V and PCO2 and calculated expired and inspired VCO2 (VCO2[E] and VCO2[I]) for each breath, whose difference equalled overall VCO2/br. The lung and Y-adapter (where the inspiratory and expiratory limbs of the circuit joined) were connected by the SS and a connecting tube in varying order. RESULTS: During ventilation of the lung model (VT = 800 ml) with SS adjacent to the inspiratory limb, VCO2[E] was 16.8 +/- 0.4 ml and VCO2[I] was 1.1 +/- 0.1 ml, resulting in overall VCO2/br (VCO2[E] - VCO2[I]) of 15.7 +/- 0.4 ml. If VCO2[I] was ignored in the determination of VCO2/br, then the %error that VCO2[E] overestimated VCO2/br was 7.2 +/- 0.3%. This %error significantly increased (p < 0.05, Student's t-test) when VT was decreased to 500 mL (%error = 12.4 +/- 0.8%) or when SS was moved to the lungward side of a 60 mL connecting tube (VCO2[I] = 2.8 +/- 0.2, %error = 18.2 +/- 1.6) or a 140 mL tube (VCO2[I] = 5.9 +/- 0.3 mL, %error = 37.5 +/- 3.3). CONCLUSIONS: When the SS was moved lungward from the inspiratory limb, instrumental dead space (VDINSTR) increased and, at end-expiration, contained exhaled CO2 from the previous breath. During the next inspiration, this CO2 was rebreathed relative to SS (i.e. VCO2[I]), and contributed to VCO2[E]. Thus, VCO2[E] overestimated VCO2/br (%error) by the amount of rebreathing, which was exacerbated by larger VDINSTR (increased VCO2[I]) or smaller VT (increased VCO2[I]-to-VCO2/br ratio).

Capnography↗
PubMed1998

Difference between arterial and end-tidal carbon dioxide pressures during laparoscopy in paediatric patients.

PURPOSE: To assess the effect of pneumoperitoneum on P(a-ET)CO2 gradient in children. METHODS: Sixty one ASA I and II children (10.7 +/- 3.0 yr, 38.4 +/- 14.2 kg, mean +/- SD), scheduled for visceral or urological laparoscopic procedures, were studied. They were anaesthetized, intubated, paralysed and their lungs ventilated with constant ventilator settings to obtain PETCO2 values between 4.3 and 4.8 kPa. Intra-abdominal pressure was maintained between 8 and 14 mmHg. The following measurements were performed at steady state, before the pneumoperitoneum (T1) and 15 min later (T2): heart rate, systolic and diastolic arterial pressure; peak airway and intra-abdominal pressure; PaCO2 corrected for the patient's temperature; PETCO2 drawn between the micropore filter and the ventilator tubes, corrected for BTPS conditions; P(a-ET)CO2. Values between -1.0 and +1.0 mmHg were considered nil; patient position (horizontal or head-down tilt): all patients were horizontal at T1. RESULTS: Arterial pressure, heart rate and peak airway pressure increased at T2: PaCO2 and PETCO2 increased by 14%. The incidence of negative gradients increased from 54 to 67% although mean P(a-ET)CO2 remained clinically unchanged. No difference was found in P(a-ET)CO2 gradient, whatever the position and intra-abdominal pressure. The 95% confidence intervals for P(a-ET)CO2 were [-5.6; +3.2] at T1 and [-8.8; +4.8] at T2. CONCLUSION: PETCO2 often overestimates PaCO2 during laparoscopy in children, by up to 8.8 mmHg. Arterial blood gas analysis should be performed during long procedures to avoid hyperventilation.

Abdomen↗
PubMed1996

Misleading end-tidal CO2 tensions.

PURPOSE: The aim of this study was to determine if the literature supported the assumption that the values and changes in end-tidal PCO2 (PETCO2) during anaesthesia accurately reflect the values and changes in arterial PCO2 (PaCO2) is tenable. METHODS: The information was obtained by (a) a Medline literature search and the appropriate references quoted in the list generated; (b) appropriate abstracts in recent issues of the annual meeting supplements of Anesth Analg, Anesthesiology, Br J Anaesth and Can J Anaesth. We specifically sought information obtained during major operations, in sick patients, and reports of serial measurements. The information obtained is summarized in graphic form, with a discussion of the mechanisms and clinical implications. RESULTS: (1) Patients with systemic disease, or when placed in the lateral position, or with haemodynamic instability have an increased Pa-PETCO2 gradient. The values during surgery are probably due to marked alterations of ventilation: perfusion relationships. (2) In a number of reports, the gradient varied widely during the procedure. (3) The gradient may be reduced due to an alteration of the configuration of the alveolar plateau. (4) The magnitude and direction of change in PaCO2 and PETCO2 can be disproportionate and in the opposite direction. CONCLUSION: End-tidal PCO2 is often not indicative of PaCO2. Also, changes in PETCO2 do not always accurately indicate the direction and extent of the change in PaCO2.

Anesthesia↗
PubMed2002

Pulse oximeter-enhanced accuracy of capnometry in children with cyanotic heart disease.

OBJECTIVES: To evaluate the relationship between the arterial end-tidal partial pressure of carbon dioxide (PCO2) difference (deltapCO2) and the degree of desaturation in children with cyanotic heart disease (CHD) and to come to a more reliable estimation of the arterial carbon dioxide partial pressure (PaCO2) from the end-tidal carbon dioxide partial pressure (PET-CO2). DESIGN AND SETTING: In part retrospective, in part prospective observational study at a university children's hospital. SUBJECTS AND INTERVENTIONS: We retrospectively assessed the relationship between the arterial oxygen saturation as measured by means of pulse oximetry (SpO2) and the arterial to end-tidal PCO2 differences (deltaPCO2) from the records of medical or surgical interventions in 43 patients with CHD. We derived a PaCO2-PET-CO2 correction formula that was prospectively validated in 34 patients with CHD. MEASUREMENTS AND RESULTS: In the retrospective part we found a significant correlation between SpO2 and deltaPCO2 ( r (2)=0.84, p<0.001). The regression equation (corrected PET-CO2=raw PET-CO2-0.36xSpO2+39) was used in the prospective part to calculate the corrected PET-CO2. The r (2)s for the correlations between PaCO(2) and uncorrected and corrected PET-CO2 were 0.17 ( p<0.05) and 0.94 ( p<0.001), respectively. The uncorrected PET-CO2 bias was 13.0 mmHg, the bias +/- 2SDs was -0.1 and 26.2 mmHg. The corrected PET-CO2 bias was -0.6 mmHg, the bias +/- 2SD's was -4.0 and 2.9 mmHg. CONCLUSIONS: Correcting the PET-CO2 for the degree of hypoxia using the SpO2 in artificially ventilated infants and children with CHD results in a clinically applicable estimation of the PaCO2. As both SpO2 and PET-CO2 can be monitored continuously and non-invasively, this could facilitate artificial ventilation management in children with CHD.

Anesthesia↗
PubMed2004

Dead space.

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Algorithms↗
PubMed2004

Tissue capnometry: does the answer lie under the tongue?

Increases in tissue partial pressure of carbon dioxide (PCO(2)) can reflect an abnormal oxygen supply to the cells, so that monitoring tissue PCO(2) may help identify circulatory abnormalities and guide their correction. Gastric tonometry aims at monitoring regional PCO(2) in the stomach, an easily accessible organ that becomes ischemic quite early when the circulatory status is jeopardized. Despite substantial initial enthusiasm, this technique has never been widely implemented due to various technical problems and artifacts during measurement. Experimental studies have suggested that sublingual PCO(2 )(P(sl)CO(2)) is a reliable marker of tissue perfusion. Clinical studies have demonstrated that high P(sl)CO(2) values and, especially, high gradients between P(sl)CO(2) and arterial PCO(2) (DeltaP(sl-a)CO(2)) are associated with impaired microcirculatory blood flow and a worse prognosis in critically ill patients. Although some questions remain to be answered about sublingual capnometry and its utility, this technique could offer new hope for tissue PCO(2) monitoring in clinical practice.

Animals↗