Thomas Prien

Secretion of brain natriuretic peptide in patients with aneurysmal subarachnoid haemorrhage

BACKGROUND Subarachnoid haemorrhage is commonly associated with natriuresis and hyponatraemia. One possible explanation for these features is a defect in the central regulation of renal sodium reabsorption with increased secretion of a natriuretic factor. We investigated whether excess sodium secretion in patients with subarachnoid haemorrhage is related to increased secretion of natriuretic peptides or to the presence of digoxin-like immunoreactive substances. METHODS We measured the plasma concentrations of digoxin-like immunoreactive substances (by a fluorescence polarisation immunoassay) and natriuretic peptides, aldosterone, renin, and antidiuretic hormone (by radioimmunoassay) in ten patients with aneurysmal subarachnoid haemorrhage, ten patients undergoing elective craniotomy for cerebral tumours, and 40 healthy controls of similar age and sex distribution. Samples were collected before surgery, 1 h, 4 h, and 12 h after surgery, then daily until 7 days postoperatively in the two groups of patients. FINDINGS All patients with subarachnoid haemorrhage, but none of the tumour patients, showed increased urine output and urinary excretion of sodium (p = 0.018 for comparison of means of curves to 7 days). The patients with subarachnoid haemorrhage had much higher plasma concentrations of brain natriuretic peptide (BNP) than controls, on admission (mean 15.1 [SE 3.8] vs 1.6 [1.0] pmol/L, p < 0.001) and throughout the study period, accompanied by lower than normal aldosterone concentrations and normal plasma concentrations of atrial and C-type natriuretic peptides (ANP, CNP). The patients with tumours had similar plasma concentrations of ANP, BNP, and CNP to the controls. We did not detect digoxin-like immunoreactive substances in either group of patients. INTERPRETATION Salt-wasting of central origin may induce hyponatraemia in patients with aneurysmal subarachnoid haemorrhage, possibly as a result of increased secretion of BNP with subsequent suppression of aldosterone synthesis.

Effect of intraoperative fluid administration and colloid osmotic pressure on the formation of intestinal edema during gastrointestinal surgery

The effects of intraoperative changes in plasma colloid osmotic pressure (COP) on the formation of intestinal edema were studied in patients during modified Whipples operation (hemipancreato-duodenectomy). Eighteen patients (ASA physical status I or II) were randomly assigned to one of three groups. They received either lactated Ringers (RL group, n = 6), 10% hydroxyethyl starch (HES group, n = 6), or 20% human albumin (HA group, n = 6) as a volume replacement solution, which was given to maintain central venous pressure (CVP) at the preoperative level. Jejunal specimens were obtained after the first transsection of the jejunum and prior to the jejuno-jejunostomy. Their water fraction (g H2O/g tissue dry weight) was measured gravimetrically. COP was determined prior to induction of anesthesia and upon removal of the second jejunal sample. In the RL group, 3,850 +/- 584 ml (data are means +/- SEM) of volume replacement solution were infused from induction of anesthesia to removal of the second jejunal sample. In the HES group, 1,358 +/- 45 ml were infused, and in the HA group, 463 +/- 49 ml were infused. During this time, COP decreased from 20.3 +/- 0.5 mmHg to 14.1 +/- 0.6 mmHg in the RL group, remained at 22.0 +/- 0.9 mmHg in the HES group, and increased from 20.7 +/- 0.9 mmHg to 28.1 +/- 0.9 mmHg in the HA group.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the haemodynamic effects of nitric oxide synthase inhibition and nitric oxide scavenging in endotoxaemic sheep

Objective: The present study compared the effects of nitric oxide (NO) synthase inhibition and NO scavenging with haemoglobin in endotoxaemic sheep. Design: 12 sheep were instrumented for chronic study. Six sheep received lG-nitro-arginine-methylester (l-NAME, 2.5 mg/kg bolus followed by a continuous infusion of 0.5 mg/kg per h), the other 6 sheep received pyridoxalated haemoglobin polyoxyethylene conjugate (PHP, 100 mg/kg bolus followed by a continuous infusion of 20 mg/kg per h). Measurements and results: Haemodynamic and oxygenation parameters were measured in healthy sheep, after infusion of Salmonella typhosa endotoxin (10 ng/kg per min) for 24 h and after infusion of l-NAME or PHP. The infusion of endotoxin resulted in a hypotensive, hyperdynamic circulation. Infusion of l-NAME increased mean arterial pressure (MAP) from 76.1 ± 4.2 mmHg to normal values of 95.8 ± 5.7 mmHg (p < 0.05). PHP increased MAP from 73.0 ± 3.0 to 88.6 ± 4.7 mmHg (p < 0.05). This increase in MAP was associated in the l-NAME group with a more prominent drop in cardiac index (from 10.2 ± 0.4 to 7.0 ± 0.5 l · min–1· m–2; p < 0.05) than in the PHP group (from 10.7 ± 0.2 to 9.3 ± 0.6 l · min–1· m–2). During the first 90 min of infusion, cardiac index remained lower in the l-NAME group than in the PHP group. The increase in pulmonary vascular resistance was also higher in the l-NAME group. Conclusion: These results suggest, that at the doses used in the experiment, NO scavenging with PHP has smaller effects on cardiac index and pulmonary vascular resistance than NO synthase inhibition with l-NAME. Therefore, the concept of NO scavenging in hyperdynamic sepsis should be further evaluated.

Differentialindikation zentraler und peripherer Leitungsanästhesien

ZusammenfassungIn den letzten Jahren wird vermehrt über schwerwiegende neurologische Komplikationen durch spinale Hämatome und Abszesse nach rückenmarksnahen Regionalanästhesien berichtet. Vor diesen Hintergrund werden die verschiedenen Regionalanästhesietechniken für die untere Extremität und ihre Komplikationen gegenübergestellt, denn die komplikationsärmeren peripheren Leitungsanästhesien bieten sich im Bereich der unteren Extremität als Alternative zur Spinal- oder Epiduralanästhesie an. Es wird empfohlen, zur postoperativen Schmerztherapie lumbale Epiduralanalgesien soweit möglich durch periphere Leitungsblockaden zu ersetzen. Kontinuierliche Blockaden, z.B. im Bereich des N. femoralis eignen sich auch zur postoperativen Schmerztherapie. Bei der postoperativen lumbalen Katheter-Epiduralanalgesie erschweren hohe Lokalanästhetika-Konzentrationen mit ausgeprägter motorischer Blockade die Diagnose intraspinaler Raumforderungen. Zur postoperativen Epiduralanalgesie sind Lokalanästhetika daher nur in niedriger Konzentration einzusetzen. Bis zum Ausschluss des Gegenteils begründet nach rückenmarksnaher Regionalanästhesie jede Zunahme der motorischen Blockade den Verdacht auf eine spinale Raumforderung (z.B. Hämatom oder Abszess). Weitere Kardinalsymptome sind Rückenschmerzen, Wurzelkompressionsschmerzen und Inkontinenz. Nur die sofortige Diagnose (MR, CT oder Myelographie) und Therapie (ggf. operative Entlastung) kann katastrophale neurologische Schäden verhindern.AbstractSerious neurological complications caused by spinal hematoma or abscess following central neuraxial block have been reported more often during the last years. In contrast, severe complications are extremely rare associated with peripheral nerve blocks. Concerned about the safety of spinal and epidural anesthesia, we encourage the use of peripheral regional techniques for procedures on the lower extremity and especially for postoperative regional analgesia. Motor block due to lumbar epidural anesthesia using high concentrations of local anesthetic makes spinal hematoma or abscess difficult to recognize. Therefore, low concentrations of local anesthestic should be used for postoperative epidural analgesia. Any increase in motor block following neuraxial blockade should raise the suspicion of a spinal compression (e.g. hematoma or abscess). Other symptoms are back pain, radicular pain or paresthesia and incontinence. Disastrous neurological injuries can only be prevented by immediate diagnosis (MR, CT or myelography) and therapy (surgical decompression).

Haemodynamic effects of dopexamine and nitric oxide synthase inhibition in healthy and endotoxaemic sheep.

Chronically instrumented awake healthy sheep (n = 6) received the synthetic catecholamine, dopexamine, during or without a background infusion of the nitric oxide synthase inhibitor. L-nitro-arginine-methylester (L-NAME). Three days later, hypotensive-hyperdynamic circulation was induced and maintained by continuous infusion of Salmonella typhosa endotoxin (10 ng/kg per min). After 24 h of continuous endotoxin infusion, the dopexamine L-NAME protocol was repeated. In healthy and endotoxaemic animals with and without nitric oxide synthase inhibition dopexamine caused the same haemodynamic changes: heart rate and cardiac output increased, mean arterial pressure and systemic vascular resistance decreased. L-NAME infusion induced normalisation of the hypotonic-hyperdynamic circulation in endotoxaemic animals. Dopexamine reduced some adverse effects of L-NAME treatment, like increased pulmonary vascular resistance and decreased oxygen delivery. In conclusion the haemodynamic effects of dopexamine are independent of the amount of nitric oxide production. Dopexamine may attenuate some of the adverse effects of nitric oxide synthase inhibition.

Effects of sympathetic nerve blockade on vasoconstrictive properties of nitric oxide synthase inhibition in sheep

OBJECTIVE Inhibition of nitric oxide synthase causes intense vasoconstriction. This effect is thought to be dependent on sympathetic nerve activity. Thus, we investigated the vasoconstrictive effects of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in sheep, in which a reversible sympathetic block was established by thoracic epidural anesthesia. METHODS Sheep (n = 11) were surgically prepared for chronic study. After at least 5 days of recovery, L-NAME was continuously administered and hemodynamics were monitored. This was done in sheep with and without sympathetic blockade in randomized order. RESULTS The vasoconstrictive effects of L-NAME were similar in sheep with and without sympathetic blockade. CONCLUSION The obtained results suggest that the vasoconstrictive properties of nitric oxide synthase inhibitors are independent of sympathetic tone.

Rückenmarknahe Regionalanästhesien bei Bakteriämie

ZusammenfassungEine Bakteriämie wird als relative oder absolute Kontraindikation für rückenmarknahe Regionalanästhesietechniken angesehen – in der Vorstellung, daß durch die spinale oder epidurale Punktion eine Meningitis oder ein epiduraler Abszess induziert werden. Tierexperimentell läßt sich eine Meningitis durch eine subarachnoidale Punktion während Bakteriämie erzeugen. Infektiöse Komplikationen nach diagnostischer Lumbalpunktion, Spinal- (SPA) und Epiduralanästhesie (EDA) sind jedoch selten, und es gibt keine Untersuchung, die ein erhöhtes Risiko bei septischen Patienten oder Patienten mit intraoperativer Bakteriämie belegt. Die wenigen Fallberichte, bei denen eine hämatogene Infektion des ZNS nach SpA oder EDA möglich erscheint, werden in dieser Übersichtsarbeit dargestellt. Es werden die Risikoabwägung bei geburtshilflicher Regionalanästhesie diskutiert, andere Faktoren, die zu infektiösen Komplikationen disponieren, in ihrer Bedeutung gewertet sowie das praktische Vorgehen für rückenmarknahe Regionalanästhesien bei möglicher Bakteriämie dargestellt. Nach bisherigem Kenntnisstand kann das Vorliegen einer Sepsis oder perioperativen Bakteriämie nur eine relative, nicht eine absolute Kontraindikation für rückenmarknahe Regionalanästhesien sein.AbstractBacteraemia and septicaemia are generally thought to be relative or absolute contraindications for central neural axis (CNA) blocks. Postulated mechanisms for haematogenous infection of the central nervous system (CNS) caused by subarachnoid or epidural puncture might be an accidental vessel puncture, a change of pressure in the subarachnoid space, and the induction of a ”locus minoris resistentiae.” Infectious complications of diagnostic lumbar puncture, spinal or epidural anaesthesia are very rare. Although in animals meningitis can be induced by subarachnoid puncture during bactaeremia, there is no study that proves an increased risk for bacteraemic patients. Transient bacteraemia is common, especially in urological and obstetrical-gynecological procedures that are often done in regional anaesthesia, but the incidence of infectious complications is low. This review investigates the few published cases in which a haematogenous infection of the CNS may have been caused by regional anaesthesia. Based on current knowledge, bacteraemia cannot be an absolute, but only a relative contraindication for CNA blocks. Antibiotic chemoprophylaxis should be given before the puncture and the patients must be closely followed after the anaesthesia, particularly for the development of spinal epidural abscess. Because of the possibly increased risk of infectious complications, informed consent should be obtained from the patient.

Die unmittelbar perioperative Phase als Bestandteil der Anästhesie Aufgaben einer perioperativen Anästhesiestation (PAS)

ZusammenfassungAufwacheinheiten dienen vor allem dem Zweck, bei rationeller Nutzung personeller und apparativer Ressourcen die Inzidenz postoperativer Komplikationen zu verringern. Im Großkrankenhaus mit operativer Akutversorgung kommen der Aufwacheinheit daneben zunehmend andere Aufgaben zu: Kurzfristige Übernahme intensivmedizinischer Funktionen, unmittelbar präoperative Maßnahmen (z.B. Einleitung von kontinuierlichen Regionalanästhesieverfahren, Optimierung von Hochrisikopatienten), postoperative Initialstellung der Analgetikapumpen im Rahmen der Akutschmerztherapie, Plazierung zentralvenöser Katheter, Betreuung unerwartet hospitalisierter Patienten nach ambulanten Operationen. Die erweiterte Aufgabenstellung für die Aufwacheinheit kann unter Umständen organisatorische Konsequenzen erfordern, beispielweise ständige ärztliche Präsenz während der Hauptbelastungszeiten oder 24stündigen Betrieb. Dann ist eine Änderung der Bezeichnung (z.B. „Perioperative Anästhesiestation”) angebracht.AbstractHistorically, recovery rooms were established in order to reduce complications in the period immediately following surgery and anaesthesia, utilising staffing and equipment resources economically. To minimise the incidence of postoperative complications remains the main task of post anaesthesia care units (PACU). However, especially in hospitals with a high degree of surgical emergencies, the scope of tasks and procedures within the PACU has expanded. Facing restricted capacities in intensive therapy (ITU) and high dependency units (HDU) the PACU serves as a buffer; intensive care functions can be covered here until the patient can be admitted to an intensive care unit. In this context, the PACU also has a switch function; postoperatively, the patient is evaluated here and the level for further treatment determined: ITU, HDU, or normal ward. The PACU period can be utilised to improve the patient’s condition (upgrade function) enabling continuation of treatment on a lower level (HDU instead of ITU, normal ward instead of HDU). This combination of buffer, switch and upgrade function is of special importance when ITU and HDU resources are limited. A new task for the PACU arises from efforts to optimise acute pain therapy; initial adjustment of continuous infusion systems according to the patients’ needs can be performed here without additional staffing requirements. Finally, the PACU can be used preoperatively for ”tune up” procedures in high risk patients. The basis for co-operation between anaesthetist and surgeon is the separation of responsibilities in combination with mutual trust. Accordingly, the anaesthetist is responsible for monitoring and maintenance of vital functions. Consequently, the anaesthetist has a professional and organisational responsibility in the PACU. The surgeon can and must rely on notification whenever surgical complications may require his intervention. With increasing comorbidity of patients and complexity of surgical procedures the anaesthetist’s responsibility in the immediate perioperative period gains a new quality. The number of surgical procedures requiring intraoperative intensive therapy from the anaesthetist is increasing; the delivery of anaesthesia becomes a background task during these operations. Thus, the anaesthetist becomes responsible for perioperative patient treatment in the operating room area which divides into three phases: preoperative ”tune up” in the PACU (e.g.) haemodynamic optimisation, starting continuous regional anaesthesia techniques), anaesthesia and support of vital functions in the OR, and immediately postoperative treatment in the PACU.

The anaesthetist makes a difference: the bottom line matters!

Editor, The editorial by Clergue critically discusses the heterogeneity of the composition of the anaesthesia team in different European countries. On the basis of the survey by Meeusen et al., the author recommends standardisation of the training, responsibilities and limitations of non-physician anaesthesia providers. The editorial further raises a question that is of utmost importance to our specialty: what is the role of non-physician anaesthesia providers in Europe, given the increasing workload combined with an expected shortage of anaesthesiologists and considerable financial restraints?

Der Einfluß von Fentanyl und endotrachealer Intubation auf die hämodynamischen Effekte der Anästhesieeinleitung mit Propofol/N2O beim Menschen

In fruheren Studien uber die hamodynamischen Effekte der Narkoseeinleitung mit Propofol, einem Phenolderivat (2,6-Diisopropylphenol) wurde uber einen signifikanten Abfall sowohl des systolischen wie des diastolischen arteriellen Blutdrucks bei stark sedierten Patienten mit KHK [2] und bei Patienten mit Veranderungen an der Aorten- und Mitralklappe [3] berichtet. In diesen Untersuchungen wurde die Zubereitung Cremophor des Propofol benutzt. Da die cremophorhaltigen Anasthetika mit signifikant haufigerem Auftreten anaphylaktoider Reaktionen einhergehen, wurde Propofol in neuer galenischer Form als wasrige Emulsion herausgebracht (1% Propofol, 10% Sojabohnenol, 2,25% Glycerol und 1,2% Phosphatid aus dem Ei; [14]. Mit der neuen Zubereitung zur Narkoseeinleitung beobachtete man einen signifikanten Abfall des arteriellen Drucks zusammen mit einer leichten Abschwachung der Herzleistung bei gesunden Personen, die normale Luft [10] oder 100%igen Sauerstoff [16] atmeten.