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Biomedical subjects

N Bruder

Publications and source records attributed to N Bruder.

At least 55 records · Page 3Linked to original sources
PubMed1999

Recovery from anesthesia and postoperative extubation of neurosurgical patients: a review.

The most feared complications after intracranial surgery are development of an intracranial hematoma and major cerebral edema. Both may result in cerebral hypoperfusion and brain injury. Arterial hypertension via catecholamine release or sympathetic stimulation and hypercapnia may be predisposing factors. Other systemic secondary insults to the brain such as hypoxia and hypotension may exacerbate neuronal injury in hypoperfused areas of the brain. Thus, the anesthetic emergence of a neurosurgical patient should include maintenance of stable respiratory and cardiovascular parameters. Minimal reaction to the endotracheal tube prevents sympathetic stimulation and increases in venous pressure. On one hand, a delayed emergence and later extubation in the intensive care unit (ICU) might be recommended to achieve better thermal and cardiovascular stability after major intracranial procedures. On the other hand, the timely diagnosis of neurosurgical complications is required to limit brain damage; the diagnosis of complications relies on rapid neurological examination after early awakening. After uncomplicated surgery, normothermic and normovolemic patients generally recover from anesthesia with minimal metabolic and hemodynamic changes. Thus, early recovery and extubation in the operating room is the preferred method when the preoperative state of consciousness is relatively normal and surgery does not involve critical brain areas or extensive manipulation. In the complicated or unstable patient, the risks of early extubation may outweigh the benefits. It is, however, often possible to perform a brief awakening of the patient without extubation to allow early neurological evaluation, followed by delayed emergence and extubation. Close hemodynamic and respiratory monitoring are mandatory in all cases. The availability of ultrashort intravenous anesthetic agents and adrenergic blocking agents has added to the flexibility in the immediate emergence period after intracranial surgery.

Anesthesia Recovery Period↗
PubMed1998

[The effects of midazolam on oxygen consumption and the level of vigilance. The possibility of the sedative effect of the plexiglas dome (canopy) of the Deltatrac indirect calorimetry device].

OBJECTIVE: To assess the effects of midazolam on oxygen consumption (VO2) and the level of vigilance. To search for a possible "sedative effect" of the canopy of the Deltatrac (Datex) when a placebo is administered instead of midazolam. STUDY DESIGN: Prospective, comparative, randomized, double-blinded, cross-over study. PATIENTS: Eight healthy volunteers of ASA physical class 1, not under stress, fasting and at rest. METHODS: The volunteers were administered at T0 either midazolam (0.07 mg.kg-1, IM), or a placebo at a one week interval in an order at random. The VO2 was measured with a Deltatrac. Circulatory status was monitored with non invasive methods and the level of vigilance assessed using the Ramsay scale. Statistical analysis was obtained with Anova for repeated measurements with two within factors (drug and time). RESULTS: VO2 decreased similarly and significantly between T0 and T45 min (P < 0.05). The decrease continued only after midazolam until T60 min. However the variation of VO2 between the midazolam and placebo group was not significant. The haemodynamic variables remained unchanged. Midazolam had a stronger sedative effect at T120 min.

Adult↗
PubMed1998

[The effect of position on intracranial pressure].

The question as to whether the head and trunk of neurosurgery patients should be elevated remains controversial. This question is particularly important when intracranial hypertension is present. Head up position may have beneficial effects on intracranial pressure (ICP) via changes in mean arterial pressure (MAP), airway pressure, central venous pressure and cerebro spinal fluid displacement. However, in some circumstances, head up position may decrease MAP which in turn will result in a paradoxical rise in ICP through autoregulation mechanisms. Therefore, the degree of head elevation has to be titrated by evaluating the most adequate cerebral perfusion pressure (CPP) for each patient by means of transcranial Doppler or measurement of jugular venous blood oxygen saturation. Head elevation above 30 degrees should be avoided in all cases. In most patients with intracranial hypertension, head and trunk elevation up to 30 degrees is useful in helping to decrease ICP, providing that a safe CPP of at least 70 mmHg or even 80 mmHg is maintained. Patients in poor haemodynamic conditions are best nursed flat. CPP is thus the most important factor in assessment and monitoring when considering head elevation in patients with increased ICP.

Humans↗
PubMed1998

[Nutritional aspects of cranial trauma].

In head-injured patients the nutritional support is aimed to prevent denutrition status usually observed. The adequate amount of calories depends on the basal metabolism (as calculated with the Harris Benedict equation). It has to be increased in case of fever (by a 0.1 factor per degree above 37 degrees C), sepsis (by a 0.1 to 0.2 factor) or when sedation is discontinued (by a 0.3 factor). The increased proteolysis is not modified by the associated treatment and results in an inevitable protein loss, whatever the qualitative change in nutritional support. In clinical practice, the nutritional support has to be adjusted continuously to the needs of the patient, to avoid a more pronounced denutrition due to the summation of daily nutritional deficits.

Craniocerebral Trauma↗
PubMed1998

The effect of hemodilution on cerebral blood flow velocity in anesthetized patients.

UNLABELLED: Transcranial Doppler is used to estimate changes in cerebral blood flow, but the effect of hemodilution on cerebral blood flow velocity (CBFV) in anesthetized patients has not been evaluated. The aim of this study was to measure the effect of isovolemic hemodilution on CBFV and lumbar cerebrospinal fluid pressure (P(CSF)) in anesthetized patients without change in other physiological variables that may affect CBFV. Patients undergoing hemodilution were compared with a control group undergoing no hemodilution. With hemodilution, hematocrit decreased from 38% +/- 3% to 30% +/- 2%, arterial oxygen content (Cao2) decreased from 17.5 +/- 1.3 to 13.9 +/- 0.9 mL/dL, and CBFV increased from 50 +/- 10 to 58 +/- 10 cm/s. An equivalent of cerebral arterial O2 transport calculated as Cao2 x CBFV did not significantly change. Over the same time interval, there were no changes in the control group. There was no statistically significant change in P(CSF), pulsatility index, Paco2, blood pressure, heart rate, or body temperature in either group. We conclude that CBFV reflects cerebral blood flow changes after hemodilution. IMPLICATIONS: Hemodilution increases cerebral blood flow but may change the cerebral artery diameter, which could confound perioperative measurement of cerebral blood flow velocity. This study found transcranial Doppler ultrasonography to accurately assess the effects of hemodilution on the cerebral circulation, but the hematocrit should be taken into account to fully understand perioperative cerebral blood flow velocity changes.

Adult↗
PubMed1998

Influence of body temperature, with or without sedation, on energy expenditure in severe head-injured patients.

OBJECTIVE: To quantify the effect of body temperature and sepsis on energy expenditure in head-injured patients. DESIGN: Prospective, nonrandomized, observational study. SETTING: Neurosurgical intensive care unit. PATIENTS: Severe head-injured patients. INTERVENTIONS: Use of an indirect calorimeter to measure energy expenditure. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure (MAP), heart rate (HR), body temperature, and mean hourly energy expenditure were recorded. Twenty-four patients had 1,919 hourly measures of the above parameters. The measurement periods were divided into four groups, according to the anesthetic agents used for sedation: fentanyl and midazolam (group FM); fentanyl, midazolam, and curarization (group C); thiopental (group T); and no sedation (group NS). The energy expenditure/basal energy expenditure ratio (EE/BEE) was significantly lower in group T (1.20 +/- 0.15) than in group FM (1.32 +/- 0.24) or group C (1.32 +/- 0.20) and was significantly higher in group NS (1.60 +/- 0.33). There was a significant correlation between body temperature and EE/BEE (p < .0001, r2 = .27) only in sedated patients. Using the equation of the regression line to correct energy expenditure for differences in body temperatures between groups, the difference in energy expenditure between groups with sedation disappeared. This finding suggested that the low energy expenditure under thiopental was due only to hypothermia. Sepsis significantly increased energy expenditure independently of fever. There was a weak but statistically significant correlation between energy expenditure and HR (p<.01, r2 = .13) but not between energy expenditure and MAP. CONCLUSIONS: Sedation had a major effect on energy expenditure. In sedated patients, body temperature was the main determinant of energy expenditure; the anesthetic agent used had little influence on the level of energy expenditure. Sepsis increased energy expenditure independently of fever, probably through hormonal changes.

Adolescent↗
PubMed1998

Catheter-related infections following axillary vein catheterization.

BACKGROUND: The aim of this study was to determine the rate of infectious complications following axillary vein cannulation and to compare to that observed after internal jugular vein catheterization. METHODS: A prospective comparative open study was carried out to determine the rate of infectious complications related to the use of catheters inserted via the axillary vein or the internal jugular vein. During the study period all patients submitted to central venous catheterization were evaluated. A total of 141 patients entered and completed the study. Catheter insertion sites were either the axillary vein punctured in the axilla, or the internal jugular vein punctured using an anterior approach. Catheter tips were cultured using a quantitative technique. Clinical information pertaining to the analysis was prospectively collected. RESULTS: A total of 141 catheters from 141 patients entered was studied. Clinical characteristics and risk factors for catheter infection were similar in both groups. The incidence of catheter-related infection (including catheter-related sepsis, and bacteremia) was not different between the two groups (axillary vein: 8.1%; internal jugular vein: 7.6%). Catheter-related bacteremia were seen at a rate of 3.7% in the internal jugular vein group and a rate of 1.6% in the axillary vein group (NS). The incidence of catheter colonization was similar in both groups (axillary vein: 14.5%; internal jugular vein: 11.4%). CONCLUSION: Catheter-related infection after axillary vein catheterization was similar to that observed after internal jugular vein catheterization. The chance of developing catheter-related sepsis was less than 10% with either route when catheters were used for the treatment of severely ill patients.

Analysis of Variance↗
PubMed1997

Intraoperative autologous blood transfusion in intracranial surgery.

OBJECTIVE: The purpose of this study was to evaluate the benefits of intraoperative autotransfusion of autologous blood on the conservation of allogenic blood, including cost-effectiveness and the consequences for hemoglobin level and coagulation tests. METHODS: The Hoemonetics Cell Saver 4 autotransfusion system (Hoemonetics Corporation, MA) was used when the estimated blood loss was equal to or more than 500 ml. A total of 472 patients undergoing intracranial surgery were included in the study. RESULTS: Ninety patients (19%) received transfusions either with autologous blood or allogenic blood. Fifty-five patients (61%) received only autologous blood transfusions, 10 patients (11%) received both autologous and allogenic blood transfusions, and 25 patients (28%) received only allogenic blood transfusions. The amount of autologous blood transfused was 600 +/- 590 ml (range, 230-3000 ml). The amount of allogenic blood transfused was 3 +/- 3 units (range, 2-15 units). Autologous blood represented 68% of all blood products transfused. Mild abnormalities during coagulation tests occurred without clinical bleeding. CONCLUSION: Autologous blood transfusions were demonstrated to be safe in patients undergoing intracranial surgery and to be more cost-effective than allogenic blood transfusions. Intraoperative autologous blood transfusions may be used alone in more than half of the patients requiring transfusions during intracranial surgery and decrease the amount of allogenic blood used. Improvements in the monitoring for the need of performing this technique, as well as preoperative blood donations, would decrease the amount of allogenic blood transfused.

Adult↗
PubMed1996

[Transfer hypokalemia induced by norepinephrine infusion].

We report a case of a severe hypokalaemia by intracellular shift of potassium in a sedated and ventilated head trauma patient. The kalaemia which was 3.9 mmol.L-1 at admission in the intensive care unit decreased to 1.3 mmol.L-1 during a perfusion of noradrenaline (0.3 micrograms.kg-1.min-1). Following the decrease of the noradrenaline dose, and administration of potassium, the kalaemia rapidly increased to 5.3 mmol.L-1 carrying a risk of arrhythmia. Therefore, kalaemia and ECG should be closely monitored when the noradrenaline doses are reduced. The causes of transcellular shift of potassium are reviewed.

Adolescent↗
PubMed1996

[Acute Weston Hurst necrotizing hemorrhagic leukoencephalitis].

The clinical and pathological findings of a 43-year-old woman, diagnosed as having acute hemorrhagic leukoencephalitis at postmortem examination, are presented. The acute hemorrhagic leukoencephalitis affects mainly young adults and is the most fulminant from of demyelinating disease. It is frequently preceded by a respiratory infection. Diagnosis is facilitated by CT scanning and MRI, which reveal the massive lesion in the cerebral white matter. Many cases terminate fatally in 2 or 4 days, but in others survival is longer. The pathological findings are distinctive.

Acute Disease↗
PubMed1995

A comparison of extradural and intraparenchymatous intracranial pressures in head injured patients.

The reliability of extradural pressure measurements for the measure of intracranial pressure (ICP) is still controversial. This study was undertaken to assess the limits of agreement between extradural and intraparenchymatous pressures using respectively the Plastimed extradural sensor and the Camino fiberoptic system. The study took place in a neurosurgical intensive care unit. Ten head injured patients were included in the study, leading to the comparison of 1032 pairs of hourly ICP values. Although the measures were significantly correlated, there was no agreement between the two methods of ICP monitoring. Extradural pressure was higher than intraparenchymatous pressure (bias 9 mmHg; 95% confidence interval of bias -9.8 to 27.8 mmHg). The lack of agreement between the two methods is probably due to the unreliability of extradural pressure for the measurement of ICP.

Adolescent↗
PubMed1995

[Patient posture in neurosurgery].

There is still controversy whether neurosurgical patients' head and trunc should be elevated or not, particularly in case of increased intracranial pressure (ICP). Head up position may have beneficial effects on ICP via changes in mean arterial pressure (MAP), airway pressure, central venous pressure and CSF displacement. However, in some circumstances, head up position may decrease MAP, which in turn will result in a paradoxical rise in ICP through autoregulation mechanisms. Therefore, the degree of head elevation has to be titrated by evaluating the most adequate cerebral perfusion pressure (CPP) for each patient by means of transcranial Doppler or measurement of jugular venous blood oxygen saturation. Head elevation above 30 degrees should be avoided in all cases. In most patients with intracranial hypertension, head and trunc elevation up to 30 degrees is useful in helping to decrease ICP, providing that a safe CPP of a least 70 mmHg or even 80 mmHg is maintained. Patients in poor haemodynamic conditions are best nursed flat. CPP is thus a most important factor to evaluate and monitor while considering head elevation in patients with increased ICP.

Blood Pressure↗
PubMed1995

[Continuous administration of mivacurium for short procedures. Delayed onset and recovery from neuromuscular blockade].

OBJECTIVE: To assess the delays of onset and spontaneous recovery from neuromuscular block produced by mivacurium administered by continuous infusion for short procedure requiring a deep relaxation. STUDY DESIGN: Prospective open non comparative study. PATIENTS: Twenty-nine class ASA I and II adults undergoing a stomatological procedure of short duration were included in the study. METHOD: General anaesthesia was obtained with a continuous infusion of propofol, supplemented with alfentanil and N2O-O2 mixture. Neuromuscular blockade, assessed with electromyography of the adductor pollicis muscle, was obtained with mivacurium (150 micrograms.kg-1). After restoration of 5% of neuromuscular transmission, mivacurium was administered by continuous infusion in order to maintain a blockade between 91 and 99%. RESULTS: The delay for decreasing twitch height by 95% was 2.9 +/- 1.0 min. The mean dose for maintenance of blockade was 10.9 +/- 1.5 micrograms.kg-1.min-1. The delay of spontaneous recovery from blockade was 10.2 min, 16.6 min and 21.3 min for obtaining 25, 75 and 95% twitchs respectively. The delay for the twitch increase from 25 to 75% was 6.6 min. DISCUSSION: Mivacurium in continuous infusion provides rapidly a deep and stable neuromuscular blockade followed by a rapid spontaneous restoration of neuromuscular transmission in patients with normal pseudocholinesterases.

Adult↗
PubMed1995

Glycosylated and non-glycosylated prolactin forms are increased after opioid administration as part of surgical anaesthesia.

OBJECTIVE: Previous studies have shown that non-glycosylated prolactin (NG-PRL) increased more markedly than glycosylated hormone (G-PRL) after TRH or metoclopramide stimulation. The aim of the present study was to determine whether such results could be extended to opioid-induced PRL stimulation. DESIGN: Open and prospective study. Using a newly developed IRMA specific for NG-PRL, we determined G-PRL and NG-PRL immunoreactivities after administration of 0.8-1.2 mg of the opioid drug phenoperidine as part of an anaesthesia. PATIENTS: Ten male patients anaesthetized for surgical treatment of a prolapsed lumbar intervertebral disc. MEASUREMENTS: Samples were obtained hourly pre and post-operatively, and every 15 minutes during operation for determination of plasma PRL, NG-PRL and G-PRL. Plasma cortisol, ACTH and GH levels were measured in an attempt to differentiate the respective roles of stress and opiate agonists in the variations of PRL levels during surgery. RESULTS: A dramatic increase in PRL levels was observed in all patients from an average of 300 +/- 90 to 1200 +/- 330 mU/l (mean + SEM) 30 minutes after drug administration. The proportion of G-PRL immunoreactivity was not significantly different when basal (25.2%) and stimulated (27%) values were compared (P > 0.05), and when mean increments of NG-PRL and G-PRL were compared (345 and 348%, respectively). The opioid drug induced a significant decrease in cortisol levels after injection and during operation (from 585 +/- 63 to 99 +/- 51 nmol/l) with a concomitant decrease in ACTH levels. GH levels were not significantly altered during anaesthesia but were significantly greater (P < 0.05) after than before surgery (5.0 +/- 1.3 vs 0.98 +/- 0.54 mU/l, respectively). CONCLUSIONS: We conclude from the present and from previous data that opioid induced anaesthesia is accompanied by an increase in both glycosylated and non-glycosylated PRL and that different PRL secretagogues may induce distinct responses in terms of PRL molecular forms.

Adult↗
PubMed1994

[Anesthesia in surgery for intracranial aneurysms].

The two major neurological complications of subarachnoid haemorrhage (SAH) due to an intracranial aneurysm are rebleeding and delayed cerebral ischaemia related to cerebral vasospasm. The best way to prevent rebleeding is early surgery. Even when surgery is performed within the first 72 hours posthaemorrhage, the risk of cerebral ischaemia due to vasospasm is high. Conventional medical treatment of cerebral vasospasm includes haemodilution, hypervolaemia and increase of arterial blood pressure. Haemodilution is of limited value as the patients suffering from SAH have usually a low haematocrit. The effectiveness of hypervolaemia is controversial and it may worsen cerebral and pulmonary oedema. Systemic hypertension is an effective therapy of vasospasm, but which can only be used once the aneurysm is controlled. Nimodipine and nicardipine, two calcium antagonists, have a beneficial effect on neurologic outcome following SAH. Today, it is still debated whether the beneficial effect of nimodipine results from the vascular effect of the drug or from a direct cerebral cytoprotective mechanism. Early surgery implies that surgeons operate on brains in acute inflammatory state. Thus, it is mandatory to use peroperative techniques improving cerebral exposure. These techniques include infusion of mannitol, lumbar cerebrospinal fluid (CSF) drainage, administration of anaesthetic agents known to decrease cerebral blood flow (CBF) and hypocapnia. Usually, the effect of CSF drainage is very effective and sufficient by itself. The second objective in the peroperative period is to avoid ischaemia. In areas with decreased flow distal to vasospasm, autoregulation is impaired and CBF is directly dependent on cerebral perfusion pressure. Furthermore, the safe practice of transient clipping of vessels supplying the aneurysm has dramatically reduced the indications of controlled hypotension. During temporary clipping, some authors recommend a pharmacological brain protection using barbiturates, etomidate or propofol, but this practice has not been validated by randomized studies. However, it is generally agreed that the arterial pressure should be increased during temporary clipping to improve collateral blood flow and to maintain it after the aneurysm has been secured. To conclude, together with lumbar CSF drainage and transient clipping, the anaesthetic management of the patients should include: maintenance of the arterial blood pressure close to its preoperative level, maintenance of PaCO2 between 30 and 35 mmHg and of normovolaemia through replacement of fluid and blood losses. After completion of surgery, recovery from anaesthesia should be rapid to allow fast diagnosis of neurological complications. The monitoring of the status of consciousness is the key of the diagnosis of early postoperative complications.

Anesthesia, General↗