In-hospital C-reactive protein predicts outcome after aneurysmal subarachnoid haemorrhage treated by endovascular coiling.

BACKGROUND: This study aimed to examine prospectively whether the inflammatory marker C-reactive protein (CRP) increases in patients with aneurysmal subarachnoid haemorrhage (aSAH) treated by endovascular coiling and investigate whether CRP could be used as prognostic factor for long-term neurological outcome. METHODS: This single-hospital study comprised 98 consecutive patients with confirmed aSAH treated by endovascular coiling. Admission status was classified according to the World Federation of Neurosurgical Societies (WFNS) Scale and initial cerebral computed tomography according to Fisher scale. CRP was analysed on days 0, 1, 2, 3, 4, 6 and 8 after the initial bleed. A neurological follow up was performed 1 year later according to the Extended Glasgow Outcome Scale (GOSE) for overall outcome and National Institute of Health Stroke Scale (NIHSS) for focal deficit. RESULTS: CRP values increased from normal to peak at 53 mg/l at day 3-4 and then declined, without normalising, at day 8. Patients with a higher increase in CRP had a poorer neurological outcome after 1 year. CRP during the first week had a stronger correlation to outcome (r = 0.417) and NIHSS (r = 0.449) than initial clinical status (WFNS; r = 0.280 and 0.274) and radiology (Fisher scale; r = 0.137 and 0.158). CRP increase indicated a risk of poor outcome (GOSE) (P < 0.001) and permanent loss of neurological function (NIHSS) (P < 0.001). Logistic regression analysis suggested that elevated CRP already on day 2 is an independent prognostic marker for outcome. CONCLUSION: Early CRP values can perhaps be used as a prognostic factor for long-term neurological outcome prediction after endovascular treatment of aSAH.

Anesthetic modulation of the cardiovascular response to microlaryngoscopy. A comparison of propofol and methohexital with special reference to leg blood flow, catecholamines and recovery.

The modulating effects of propofol versus methohexital on the cardiovascular response to microlaryngoscopy were studied in 35 patients divided into four equal groups (one patient participated twice). Heart rate (HR), mean arterial blood pressure (MAP, cardiac output (CO; impedance cardiography), leg blood flow (LBF; occlusion plethysmography) and concentrations of arterial catecholamines were measured. After administration of atropine and fentanyl (2 micrograms.kg-1), anesthesia was induced by either an injection of propofol (2.0 mg.kg-1) followed by a low (6 mg.kg-1.h-1; n = 9) or a high (12 mg.kg-1.h-1; n = 9) dose propofol infusion or an injection of methohexital (1.5 mg.kg-1) followed by a low (5 mg.kg-1.h-1; n = 9) or a high (10 mg.kg-1.h-1; n = 9) dose methohexital infusion. The low methohexital infusion dose was insufficient to control MAP, which increased 41% during microlaryngoscopy compared to the awake state. The HR increased in all groups but the increase was most prominent in the low dose methohexital group. There were no statistically significant changes in CO in any group, whereas LBF increased consistently in all groups except in patients anesthetized with the low dose of methohexital. The increases of LBF in the propofol groups were intermediate and not dose dependent. The methohexital low dose group showed increases in norepinephrine levels compared to awake values and in epinephrine levels compared to the other groups. Propofol seems to differ from methohexital in modulation of peripheral vascular tone.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic gas exchange during aortocoronary bypass surgery using a double pump system and mechanical ventilation. A comparison between indirect calorimetry and invasive blood gas measurements using Fick's principle.

Oxygen uptake and carbon dioxide excretion during aorto-coronary bypass surgery were studied in seven patients by indirect calorimetry and compared to blood-gas based measurements. Medium-high dose fentanyl, droperidol and midazolam were used for maintaining anaesthesia. During the period of extracorporeal circulation no external oxygenator was used. Circulation was maintained by two pumps by-passing the left and right heart respectively and the patient's lungs were ventilated with O2/N2 using a Servo 900C ventilator. For indirect calorimetric measurements gas concentrations were analysed by Beckman instruments and gas volumes were measured by the Servo 900C ventilator. Oxygen uptake and carbon dioxide excretion decreased by 31% and 39%, respectively. For invasive measurements during extracorporeal circulation, arterial and venous blood gases and pump flow were used. Using pump flow instead of cardiac output when calculating oxygen uptake circumvented errors in thermodilution measurements. There was a good correlation (r = 0.88) between the invasive and the indirect calorimetric measurements. Further, there was a good correlation between naso-pharyngeal temperature and indirect calorimetric measurements of oxygen uptake (r = 0.87).

Validation of a system for measurement of metabolic gas exchange during anaesthesia with controlled ventilation in an oxygen consuming lung model.

An oxygen consuming lung model was used for evaluation and validation of a technique for metabolic gas exchange measurements during controlled ventilation. The technique comprised a Servo 900 C ventilator (Siemens) and separate oxygen and carbon dioxide analysers (Beckman). Measurements of oxygen consumption and carbon dioxide production were made either by measuring inspired and expired ventilation and gas fractions in these volumes or by measuring gas fractions and calculating expired ventilation from inspired by transformation (Haldane). Irrespective of the FIO2, measured values correlated well with lung model settings: measured values were within +/- 2% of simulated. When Haldane transformation was used with an FIO2 of 0.5 there was a significant underestimation of oxygen consumption. Carbon dioxide production values correlated well irrespective of the FIO2 used or method of measurement of ventilation volume. Metabolic gas exchange measurements by measuring both inspired and expired ventilation volumes may be used when inert gases are not in equilibrium, for example during nitrous oxide anaesthesia.

Metabolic gas exchange during nitrous oxide anaesthesia with controlled ventilation.

A system for metabolic gas exchange has been used during nitrous oxide-opioid anaesthesia incorporating a Servo Ventilator 900 C and external analysers for oxygen and carbon dioxide. Oxygen consumption and carbon dioxide excretion were calculated as differences in content between inspired and expired minute ventilation. Nitrous oxide uptake was calculated similarly, assuming it was the only other gas present in addition to oxygen and carbon dioxide. The mean value for oxygen consumption was 3.25 ml kg-1 min-1, declining by 8% during the 2 h of anaesthesia. The formula for the best fit curve of nitrous oxide uptake was 18.3 . t-0.48 ml kg-1 min-1 when FIN2O was 0.7. To simplify measurement procedures and avoid measurements of expiratory volume, we also calculated metabolic gas exchange when expiratory minute ventilation was expressed as a function of inspiratory minute volume and nitrous oxide uptake. The latter value was obtained from the overall best fit curve for nitrous oxide uptake.

Humidity of the Bain and circle systems reassessed.

The humidity outputs of the Bain circuit, a traditional non-coaxial Mapleson D system, and a circle system with and without a soda lime absorber were evaluated in a laboratory model simulating a 70-kg subject. The breathing systems were tested with tidal volumes of 0.35 and 0.70 L and frequencies of 10-20 breaths/min to maintain an end-expiratory CO2 of 4.5%. There were small differences in inspiratory gas humidity between the Bain and the non-coaxial Mapleson D system. With a fresh gas flow of 5 L/min in the Bain circuit, the humidity was 9.8-16.5 mg H2O/L depending on tidal volume and respiratory frequency. The humidity output of the circle absorber system with fresh gas flows of 0.5 or 2 L/min was 21.6-25.2 mg H2O/L at 60 min. Therefore, this study does not support previous studies, which propose that the Bain circuit has superior humidifying properties compared with those of the circle absorber system.

Whole body gas exchange: amino acid and lactate clearance as indicators of initial and early allograft viability in liver transplantation.

A method for the rapid assessment of liver allograft circulation and function after liver transplantation is described. In 12 patients undergoing liver transplantation continuous recording of whole body energy production was made on the basis of gas exchange measurements during the surgical procedure. Oxygen consumption decreased rapidly by 25% when the blood supply to the native liver was interrupted. After the anhepatic period, there was a sharp increase of oxygen consumption with successful reperfusion of the allograft. Carbon dioxide production fell by 14% and returned to preanhepatic values after successful declamping. In two cases with suboptimal reperfusion the return of gas exchange values was slow and incomplete. Results from the studies of whole body energy production were compared with biochemical measurements. No significant accumulation of amino acids occurred during the anhepatic period, but in the two patients with incomplete revascularization, clearance of amino acids, after the anhepatic phase, was impaired and plasma amino acids accumulated. The same pattern was found for plasma lactate levels. By the techniques described in this article, rapid and reliable assessment of initial and early graft function in hepatic transplantation is possible. This is of great value for the intraoperative and early postoperative assessment and planning of surgical and anesthesiologic strategies.

Leukocyte effects on microcirculation in artificially perfused rat lungs.

Evidence indicates that leukocyte microvascular flow obstructions play an important role in no-reflow phenomena after ischemia and that leukocytes may cause significant disturbances of capillary perfusion in low flow states. In the present study, a cell-free colloid perfusion (20-60 ml.kg-1.min-1) of isolated ventilated rat lungs was interrupted by bolus injections of leukocytes in varying numbers. Leukocyte effects on flow resistance, tracer gas exchange, and micromorphology were evaluated. The vast majority of the infused leukocytes remained trapped in the lungs after repeated infusions regardless of the number of leukocytes given, although leukocyte trapping decreased at the higher flow rates. The functional and morphological analyses showed that the polymorphonuclear granulocytes had a greater tendency than the mononuclear cells to become permanently trapped in the pulmonary capillaries. The tracer gas analyses indicated that the trapped leukocytes were scattered in the alveolar capillary networks and did not cause complete exclusion of flow from the affected alveoli. This was probably due to the anatomy of the pulmonary microvasculature, with its abundancy in interconnecting pathways.

Low-flow anaesthesia does not increase the risk of microbial contamination through the circle absorber system.

In the circle absorber system, a decrease in fresh gas flow means a higher degree of rebreathing, and, consequently, a higher temperature and humidity within the system. With our present hygienic routines, the circle system tubings are changed and decontaminated once daily. Thus, the same circle system is used for several patients each day. In order to evaluate whether the risk of bacterial contamination increased with the introduction of low-flow anaesthesia, 122 patients anaesthetized with either a low-flow technique (less than 1.5 l fresh gas flow/min) or with medium fresh gas flows (3-6 l/min) were studied. Bacterial samples were taken preoperatively from the oropharynx and postoperatively from five locations in the circle system. The patients were studied postoperatively for signs of respiratory tract infection. There were few positive bacteria cultures from the tubings in the circle system, regardless of fresh gas flow. No pathogens were found in the inspiratory tubings and no cases of postoperative respiratory tract infection could be related to bacterial spread from the anaesthesia machine. There were no indications that the present hygienic management was insufficient for the medium- or the low-flow circle system techniques.

Gaseous homeostasis during low-flow anaesthesia.

The object of this clinical study was to investigate the circle system gas homeostasis during low-flow anaesthesia using a technique designed to keep a constant inspired oxygen fraction of 0.30. Denitrogenation was adequately accomplished with mask preoxygenation, 10 l/min, for 1 min and an initial fresh gas flow of 5 l/min for 6 min after intubation. There was no need to wash out accumulated nitrogen at intervals, since the already low nitrogen concentration in the system tended to decrease after 1 h. The fresh gas flow of nitrous oxide to oxygen ratio and the inspiratory to end-expiratory oxygen concentration difference both reflected the uptake of nitrous oxide. The calculated rates of uptake of nitrous oxide, a subject of controversy, were in accordance with those found by Severinghaus and Barton & Nunn.

Postganglionic sympathetic nerve activity in halothane-anaesthetized rats during controlled and spontaneous ventilation.

The aim of the study was to compare the effect of halothane anaesthesia on sympathetic nerve discharge in mechanically normoventilated and spontaneously breathing rats. Renal sympathetic nerve activity (rSNA), mean arterial pressure (MAP) and heart rate (HR) were measured in the conscious state and at the inspiratory halothane concentrations of 0.6%, 1.2% and 2.4% in one mechanically normoventilated and one spontaneously breathing group, while a third group was subjected to controlled hypoventilation at 1.2% halothane concentration. Halothane in blood was determined in two separate groups at 1.2%. In an additional group of spontaneously breathing rats, PaCO2 was analysed during consciousness and the halothane concentrations of 1.2% and 2.4%. There was a pronounced decrease in rSNA, MAP and HR at all levels of anaesthesia in the mechanically ventilated rats. However, rSNA, HR and MAP were significantly higher in the spontaneously breathing rats at increasing levels of halothane anaesthesia. Controlled hypoventilation at 1.2% halothane increased the variables significantly. In spontaneously breathing animals, PaCO2 increased significantly during the halothane exposure. The concentration of halothane in blood was significantly higher in the spontaneously breathing rats. Thus, the halothane-induced respiratory depression in the spontaneously breathing rats preserved rSNA during halothane anaesthesia, possibly via CO2-mediated chemoreceptor stimulation.

Comparison of costs of different anaesthetic techniques.

The costs of anaesthetic drugs, intravenous agents as well as gases, were studied for different anaesthetic techniques in a medium-sized operative procedure, cholecystectomy. Three anaesthetic breathing systems were used: a non-rebreathing system, a circle absorber system with medium fresh gas flows of 3-6 l/min, and a low-flow circle system. Anaesthesia without volatile inhalation agents used with a low-flow technique was the least expensive, and anaesthesia with isoflurane in a non-rebreathing system was the most expensive. The costs of anaesthesia without volatile inhalation agents in a non-rebreathing system, enflurane anaesthesia in a circle system with medium fresh gas flows, and isoflurane anaesthesia with low-flow technique were similar.

Preservation of humidity and heat of respiratory gases during anaesthesia--a laboratory investigation.

Humidification and heating of anaesthetic gases are desirable to prevent respiratory tract damage and a fall in body temperature during operative procedures. Numerous studies on the humidity and temperature of inspiratory gases in different breathing systems for anaesthesia have been carried out, but comparisons are difficult since different methods have been used. In this laboratory set-up we studied a non-rebreathing system with and without humidifiers and a circle absorber system with low (0.5 l/min) or medium (5 l/min) fresh gas flows regarding their ability to heat and humidify anaesthetic gases. The humidity of inspired gases was acceptable in the non-rebreathing system using either a Bennett Cascade humidifier or disposable humidifiers and in the circle absorber system using a fresh gas flow of 5 l/min or less. The temperature of the inspired gases was highest with the Bennett Cascade humidifier, followed by the low-flow circle system. The circle absorber system used with low fresh gas flow gave higher inspiratory gas temperature and humidity than the non-rebreathing system with a good disposable humidifier.

Oxygen analyzers in anaesthesia: performance in a simulated clinical environment.

Nine commercial oxygen analyzers were tested in a laboratory model stimulating clinical anaesthesia conditions. Fifteen test situations were used in order to study the effects of nitrous oxide, humidity, positive end-expiratory pressure, halothane, enflurane and isoflurane. Errors exceeding 8 vol% were not uncommon, the dominating source of error being humidity. Analyzers with efficient dehumidification of gases before analysis performed better than analyzers without this property.

Methohexitone anaesthesia for microlaryngoscopy: circulatory modulation with metoprolol and dihydralazine.

Anaesthesia for microlaryngoscopy was induced and maintained with fentanyl 3 micrograms kg-1 and methohexitone (initial bolus of 1-1.5 mg kg-1 plus subsequent infusion of 4 mg kg-1 h-1). Suxamethonium was used to induce neuromuscular blockade. Twenty minutes before induction of anaesthesia, previously normotensive patients (n = 35), and patients with hypertension well controlled by beta-receptor antagonists (n = 16) were pretreated with metoprolol (M) 0.2 mg kg-1 i.v. and dihydralazine (DH) 0.2 mg kg-1 i.v., dihydralazine 0.2 mg kg-1 i.v. alone, or saline. Arterial pressure (AP) and heart rate (HR) were monitored: any arrhythmia and ST60-T changes were noted. After the methohexitone infusion was stopped, the times for emergence and full recovery were short (median 2 min 15 s and 5 min later, respectively). Pretreatment with M + DH abolished increases in AP and HR during endoscopy. Arrhythmias were observed in fewer pretreated patients than in controls (P less than 0.05). ST60-T changes in the ECG indicating myocardial ischaemia were found in two of 19 M + DH and in six of 21 saline-pretreated patients. One of these six patients developed a myocardial infarction. Pretreatment with dihydralazine alone attenuated the pressor response to microlaryngoscopy, but was associated with consistently high HR and an incidence of arrhythmias as well as ST60-T changes similar to that found after saline.

Effects of the rectal administration of diazepam. Diazepam concentrations in children undergoing general anaesthesia.

Diazepam 1 mg/kg body weight was administered rectally to 14 children (11-22.5 kg) before minor surgery under general anaesthesia. Administration in solution (n = 7) resulted in a rapid increase in serum concentrations which were maintained for 8 h. Administration by suppository (n = 7) resulted in significantly lower serum concentrations at 10 and 20 min, but higher concentrations at 2 h. At other intervals the concentrations did not differ from those reached after administration of diazepam in rectal solution. These results favour for use of a solution when rectal diazepam is used for premedication in children.