Ch. Maier

Postoperative pain management on surgical wards. Eight years' experience of an anaesthesiology-based acute pain service

Zusammenfassung. Seit 1985 wurden 1947 Patienten durch einen Anästhesiologischen Schmerzdienst auf Allgemeinen Krankenpflegestationen an insgesamt 13 971 Tagen betreut. Bei den 1736 Patienten mit Epiduralanalgesie (EA) mit 0,175 – 0,25% Bupivacain betrug die mittlere Behandlungsdauer 7 (1 – 53) Tage, bei 50% der Patienten länger als eine, bei 11% mehr als 2 Wochen. 183 Patienten mit PCA (Tramadol, Piritramid) wurden im Mittel an 4 (1 – 23) Tagen, hiervon 21,4% länger als eine Woche behandelt. Seit Einführung des Schmerzdienstes sank die Häufigkeit therapiebedingter Komplikationen unter der EA von 10,4% signifikant auf 6% in den letzten beiden Jahren, z. B. traten gravierende Hypotensionen in den letzten Jahren nicht mehr auf. Obwohl nur in Ausnahmefällen eingesetzt, traten zwei Fälle einer schweren Atemdepression nach epiduralem Morphin auf. Unter der PCA wurden ebenfalls zwei Fälle (1% der Anwendungen) beobachtet. Außerdem wurden vier schwere Komplikationen mit einem Todesfall im Rahmen der nicht vom Schmerzdienst betreuten Standardschmerztherapie dokumentiert. Die Anbindung des Schmerzdienstes an den Aufwachraum hat sich bewährt, da hier die Wirksamkeit und Verträglichkeit der auf den Allgemeinstationen vorgesehenen Therapie geprüft werden kann. Auf den Stationen muß mittels täglicher Visiten anhand standardisierter Protokolle der weitere Verlauf systematisch überwacht werden. Unter diesen Rahmenbedingungen ist die Schmerztherapie auch mittels spezieller Verfahren (EA, PCA) auf Allgemeinen Pflegestationen praktikabel und vertretbar.Abstract. Despite major advances in knowledge and development of efficient techniques for pain control, many patients on surgical wards suffer from modest to severe pain following surgery or trauma. Therefore, in the University Hospital of Kiel, Germany, an anaesthesiology-based acute pain service (APS) was started in 1985 to improve this situation. Organization of an APS. The anaesthesiologist in training who manages the recovery unit serves as an APS for surgical wards and is supervised by a consultant. The anaesthesists on call are responsible after regular working hours. The activities of the APS are as follows: 1. Induction of sufficient postoperative analgesia in the recovery unit for all surgical patients. 2. Clinical rounds on all patients receiving epidural analgesia (EA), other forms of regional analgesia, or patient-controlled analgesia (PCA) every morning and throughout the day if necessary. 3. Additional consultations for postoperative pain management for other patients on request. 4. Assessment and documentation of the clinical status of the patient, quality of analgesia, and side effects. 5. Writing orders for further treatment. 6. Continuing consultations and informal education for ward nurses, physiotherapists, and surgical staff; formal medical training for ward nurses in postoperative pain management. Activity of the APS. From 1985 to 1992, 1947 patients on normal wards were treated (EA: 1736, PCA: 183). Epidural analgesia was performed using a standard protocol with bupivacaine 0.175% – 0.25% infused continuously with top-ups if needed (mean 240 mg/day, range 75 – 600 mg; median duration 7 days, range 1 – 53, Table 1). Demand for further treatment was proved by day-to-day withdrawal. Since the introduction of an APS, complications of EA such as hypotension (1985/1986: 5.1%; 1987/1992: 0.5%, Table 3) and insufficient analgesia due to dislocation or other technical complications could be reduced significantly (Table 3). Dermal infections were seen in 2.6% of patients, with a significantly higher incidence in patients with arteriosclerotic diseases (4.1%). Epidural opioids were used in only 46 selected cases on surgical wards. Nevertheless, 2 cases of marked respiratory depression occurred. The overall risk of complications during postoperative EA could be reduced from 1 : 11 cases in the first 2 years to 1 : 20 in the last 6 years since introducing the APS. For other regional procedures (e.g., interpleural analgesia) no complications were recorded. PCA was performed using a standard protocol with tramadol or piritramide without background infusion (Table 6). The loading dose was titrated in the recovery unit. The median duration of PCA was 4 days (range 1 – 23); the median dose of piritramide was 45 mg/day (range 3 – 226 mg). Two cases of somnolence and respiratory depression occurred. In this period there were 8 potential life-threatening complications due to postoperative pain therapy; 4 occurred during standard surgical pain management (3 cases of severe respiratory depression after i.m. and i.v. piritramide (unsuccessfull resuscitation), tramadol, and buprenorphine; 1 small child with multiorgan failure after paracetamol intoxication). In those cases the APS was not involved. Conclusions. There are insufficient data for comparison of the incidence of complications following standard management of postoperative pain relief without an APS, i.e., i.m. injections of opioids on request, but severe and sometimes lethal complications have been reported. Since the majority of patients used EA or PCA for several days, it is again emphasised that these techniques should not be restricted to high-dependency areas such as intensive care or recovery units. The introduction of an APS is an adequate approach to more efficient and safer pain management on surgical wards. This requires standard protocols (Table 7), standardised monitoring and trained ward nurses. Based on our experience, most complications develop slowly, and risk factors can be recognised early enough to avoid severe sequelae. The routine use of epidural opioids on surgical wards is not recommended unless special monitoring (e.g., pulse oximetry) is provided. Establishing an APS is a major future challenge for anaesthesiologists. Nevertheless, surgeons should also participate to improve the standard of pain management. We should be aware that this service can not be run efficiently during simultaneous activity in the operating room.

Diagnostik und Therapie des sympathisch unterhaltenen Schmerzes

ZusammenfassungDer „sympathisch unterhaltene Schmerz” (SMP) ist ein Symptom mit variabler Ausprägung und Häufigkeit mit verschiedenen Schmerzerkrankungen (u.a. CRPS, Zoster- und posttraumatische Neuralgie), das in einen vom Sympathikus unabhängigen Schmerz (SIP) übergehen kann. Ein SMP kann nicht durch klinische Merkmale, sondern nur durch die Analgesie nach einer Sympathikusblockade verifiziert werden. Die Interventionsverfahren (Grenzstrangblockade, IVRS, GLOA) unterscheiden sich hinsichtlich ihrer diagnostischen Sensitivität und Spezifität und der therapeutischen Effektivität. Das Risiko einer falsch-positiven Diagnose eines SMP wird durch optimale Technik und differenzierte Dokumentation, das einer Fehldiagnose eines SIP nur durch aufwendiges Monitoring (Messung sympathischer Reflexe) verringert. Es werden ein Modell für den Pathomechanismus, das die klinische Symptomatik in bislang experimentell begründete Hypothesen integrieren soll, sowie Algorithmen für die Diagnostik und die Therapie des SMP diskutiert.AbstractThe term ”sympathetically maintained pain” (SMP) describes a symptom that might accompany a variety of diseases (CRPS, (post-) herpetic and post-injury neuralgia), which might transform into sympathetically independent pain (SIP) after some time. Patients with SMP present a bunch of disorders of the autonomic and sensory system, but the only reliable way to diagnose a pain as SMP is a positive response to an intervention at the sympathetic nervous system. Three ways of influencing the sympathetic system are commonly used: (a) local anesthetic sympathetic blockade (SB), (b) intravenous regional sympathectomy (IVRS) and (c) ganglionic local opioid application (GLOA). A review of current literature shows that SB has certain advantages in diagnostic sensitivity, whereas GLOA might be slightly superior in therapy of some diseases with longstanding pain history. Obviously, the therapeutic benefit of all interventions is complete independent of the accompanying autonomic disorder and of a blockade of efferent fibers. A new heuristic model of the SMP mechanism is presented, including both experimental and clinical data. For reducing the risks of false positive or negative diagnosis of SMP and SIP, a diagnostic algorithm is proposed. This includes optimizing the technique, changes of interventional measures, and adequate monitoring both of analgesia and as well of the extend of efferent sympathetic blockade (e.g. measurement of sympathetic reflexes). The treatment recommendations in patients with SMP vary in dependence of the kind of disease. In SMP, invasive measures play an important, but only limited role within the comprehensive treatment concept. As an example a three-stage, symptom-adapted treatment algorithm is demonstrated for CRPS, including also drug therapy, psychologic and physiotherapeutic approaches.

Pharmacokinetics and protein binding of bupivacaine in postoperative epidural analgesia

We describe a method, which is both specific and rapid, for the measurement of bupivacaine concentrations in plasma using high‐performance liquid chromatography. Bupivacaine plasma concentrations, pharmacokinetics and protein binding in the postoperative period were investigated in seven patients (58–77 years old) following hip surgery. Postoperative analgesia was achieved by epidural bolus injections of 25 mg bupivacaine 0.25% every 6 h. Sufficient pain relief without side‐effects was obtained. Total (maximum 1.13 μg/ml) as well as free (maximum 0.1 μg/ml) bupivacaine plasma concentrations remained below toxic threshold levels and no cumulation occurred. Increased protein binding in the postoperative period is reported, emphasizing the importance of measuring the free fraction in addition to the total plasma concentration. The free fraction decreased from 5.4% preoperatively to 2.7% in the postoperative period (P<0.05). Changes in plasma protein binding of bupivacaine and changes in plasma levels of the acute phase reactant α‐1‐acid glycoprotein were correlated (r = 0.8, P<0.05). Difficulties in interpreting the elimination parameters following epidural administration are discussed, leading to the conclusion that the derivation of dosage regimens from kinetic parameters following epidural administration is not warranted.

Plasma protein binding of bupivacaine in pregnant women at term

The increased toxicity of bupivacaine in parturients is a well‐known phenomenon. The reduced plasma protein binding of bupivacaine is one of the possible reasons. Therefore, we measured the free fraction of bupivacaine in plasma samples of parturients and non‐pregnant volunteers. The free fraction was significantly higher in parturients (8.2% vs 5.4%) associated with a lower concentration of the alpha‐1‐acid glycoprotein (0.42 vs 1.01 g/l) and a higher concentration of progesterone (156 vs 0.4 ng/ml). The addition of progesterone to plasma samples of non‐pregnant volunteers did not influence the free fraction of bupivacaine, whereas the addition of alpha‐1‐acid glycoprotein to the plasma of parturients decreased the free fraction significantly. Therefore, the lower concentration of this protein is the principal reason for the higher free fraction of bupivacaine in pregnancy and possibly one of the causes of the higher incidence of toxic side effects of bupivacaine in obstetric use.

Intraoperative monitoring with somatosensory evoked potentials in carotid artery surgery - less reliable in patients with preoperative neurologic deficiency?

Background: In a retrospective analysis of intraoperative somatosensory evoked potential (SEP) results during carotid artery surgery we found some cases with postoperative neurologic deficits, surprisingly without significant SEP changes.

Complex regional pain syndrome. Sympathetic reflex dystrophy and causalgia

ZusammenfassungKomplexe regionale Schmerzsyndrome (CRPS) entstehen als inadäquate Konsequenz eines schmerzhaften Traumas einer distalen Extremität. Beim CRPS I (sympathische Reflexdystrophie) ist keine Nervenläsion nachweisbar.Neben Sensibilitätsstörungen sind brennende tiefe Spontanschmerzen und eine mechanische Allodynie charakteristisch. Störungen der Hautdurchblutung, des Schwitzens, ein Ödem und im weiteren Verlauf trophische Störungen der Haut,Gelenke und Knochen sind typisch.Zu den motorischen Störungen zählen eine Einschränkung der Muskelkraft, ein Tremor und später dystone Veränderungen.Alle Symptome sind generalisiert in der distalen Extremität vorhanden und nicht auf das Ausbreitungsgebiet peripherer Nerven begrenzt.Das CRPS Typ II (Kausalgie) entwickelt sich nach einer partiellen peripheren Nervenläsionen. Die distal generalisierten Symptome sind identisch.Der Erfolg der Therapie hängt von einem frühen interdisziplinären Behandlungsbeginn ab.Neben der Schmerztherapie ist die Physiotherapie entscheidendend für die Rehabilitation. In der Akutphase muss zunächst Schmerzfreiheit in Ruhe und ein Rückgang des Ödems erreicht werden.Bei geringen Spontanschmerzen ist ein konservativer Therapieansatz (Analgetika, Ruhigstellung,Hochlagerung) vertretbar.Bei unzureichender Besserung und in schweren Fällen wird der Effekt interventioneller Behandlungsverfahren (Sympathikusblockaden) getestet und evtl. eine Blockadeserie eingeleitet.Nach Rückgang der Spontanschmerzen wird stufenweise die Physiotherapie intensiviert.SummaryComplex regional pain syndromes (CRPS) occur as the inadequate response to painful trauma in a distal extremity.With CRPS I (sympathetic reflex dystrophy), no lesion of the nerve is present. Aside from sensory disturbances, burning deep spontaneous pain and mechanical allodynia are characteristic.Disturbances in the skin blood circulation,sweating,edema,and trophic disturbances of the skin, joints, and bones are typical.Reduction in muscle strength, tremor, and late dystonic changes comprise the motor disturbances.All symptoms are distributed in the distal extremity and not limited to the region of the peripheral nerves.Complex regional pain syndrome II (causalgia),develops following a partial peripheral nerve lesion.The distally generalized symptoms are identical.Successful therapy depends on an early start of interdisciplinary treatment.In addition to the pain therapy,physiotherapy plays a decisive role in rehabilitation. During the acute phase, freedom from pain at rest and retrogression of the edema must be achieved.With slight spontaneous pain, a conservative therapeutic method may be applied (analgesics, rest, raised position). In case of insufficient improvement and in difficult cases, the effect of intervention (sympathetic blockade) should be tested and possibly a blockade series performed.After reduced spontaneous pain,physiotherapy should be increased stepwise.

Neurological complications and loss of efficacy with intrathecal pain therapy

ZusammenfassungIn einer neuen Leitlinie der DGSS wird die intrathekale Opioidtherapie als nachgewiesen effektiv und relativ nebenwirkungsarm beschrieben. Wir überprüften diese Aussage durch eine Literaturauswertung und kritische Sichtung von Krankenverläufen eigener Patienten (n=3). In diesen Fällen (sowie 8 weiteren) führte die Explantation und Umstellung auf orale Opioide zu einer deutlich besseren Schmerzlinderung sowie zum Abklingen der unerwünschten Ereignisse.Die von uns diskutierten Probleme scheinen keine Raritäten zu sein, sondern Komplikationen, die durchaus häufig beschrieben werden. Die Langzeitwirksamkeit intrathekaler Opioide ist nicht ausreichend belegt, ihre Wirkstärke zudem nicht hoch. Die Häufigkeit unerwünschter Ereignisse ist vergleichbar mit der einer oralen Opioidmedikation, allerdings sind gravierende neurologische Komplikationen möglich. Um Dosiseskalationen zu vermeiden und neurologische Komplikationen rechtzeitig zu erkennen, ist eine konsequente Nachkontrolle durch den Operateur oder durch ein erfahrenes Schmerzzentrum erforderlich.AbstractIn a new guideline issued by the German Association for the Study of Pain, intrathecal opioid therapy is described as proven to be effective with relatively few side effects. We reviewed this statement by analysis of the available literature and critical evaluation of the clinical course in a few of our own patients (n=3). In these cases (as well as in a further eight patients), explantation and a switch to oral opioids led to distinctly better alleviation of pain and abatement of the unwanted effects.The problems we discuss do not appear to be rare instances, but by all means complications that are frequently described. The long-term efficacy of intrathecal opioids has not been adequately verified; moreover, their potency is not high. The frequency of undesired events is comparable to that of oral opioid medication, but serious neurological complications are possible. To avoid dose escalations and to recognize neurological complications in time, diligent monitoring by the surgeon or an experienced pain center is essential.

Lebensbedrohliches postoperatives Angioödem nach Einnahme von ACE-Hemmern

ZusammenfassungBerichtet wird der Fall eines Angioödems im Gesicht und im Mund nach zuvor unkomplizierter 18monatiger Einnahme des ACE-Hemmers Quinapril. Es trat 10 Tage nach einer Spinalanästhesie auf, vermutlich ausgelöst durch eine Verschlechterung der Nierenfunktion und gleichzeitiger Gabe von Diuretika. Nach zunächst erfolgreicher Behandlung mit Kortikoiden kam es vier Tage später zu einem Rezidiv mit lebensbedrohlicher Verlegung der Atemwege, das medikamentös unbeeinflußbar blieb. Eine Notfallintubation war nur endoskopisch möglich. Nach Absetzen der Medikation war der weitere Verlauf ungestört. Wie in anderen publizierten Fällen auch wurde trotz eindeutiger Frühsymptome keine Beziehung zur Medikation mit Quinapril hergestellt und diese zu spät abgesetzt. Angesichts der zunehmenden Häufigkeit der Verordnung langwirksamer ACE-Hemmer müssen Anästhesisten und Intensivmediziner mit einer erhöhten Inzidenz dieser Komplikation rechnen, zumal das Risiko einer postoperativen Manifestierung erhöht zu sein scheint. Deshalb sollten die Pathogenese dieses Ödems und die notwendigen therapeutischen Maßnahmen bekannt sein, nachdem zwischenzeitlich bereits Todesfälle publiziert wurden.AbstractAngio-oedema is a recognised complication of angiotensin converting enzyme (ACE) inhibitor therapy, occurring in 0.1% to 0.5% of patients taking captopril, enalapril, or lisinopril. This is the first report of severe angio-oedema complicating therapy with quinopril, a new, long-acting drug. Case report. A 74-year-old female had been taking quinapril (10 mg/day) and diuretics (fixed combination of triamterene and hydrochlorothiazide) for arterial hypertension for 18 months without any complication. After a fracture of the ankle, the patient received spinal anaesthesia uneventfully for an osteosynthesis. Ten days postoperatively, she noted swelling of the lips and the left half of the tongue. Following intravenous injection of antihistamines and predisolone, these symptoms regressed. However, a relapse occurred on the 16th postoperative day with rapidly increasing oedema of the lips, face, ventral collar area, and entire tongue. Despite high-dose steroids, dyspnoea developed within 2 h. Direct laryngoscopy was impossible, and a flexible bronchoscope was used for nasotracheal intubation. At this point, the diagnosis of ACE inhibitor-induced angio-oedema was made and quinapril was withdrawn. The patient recovered, tracheal extubation was performed after 48 h, and the later course was uneventful. Discussion. This is the second report of angio-oedema as a postoperative complication in a patient on long-term and previously unremarkable ACE inhibitor therapy. The first reported case occurred immediately after oral intubation and was perhaps precipitated by mechanical irritation. In this case, it is likely that postoperative deterioration of renal function due to dehydration and diuretic therapy was the precipitant, as has been reported in patients on lisinopril without surgery. Despite a significant increase in angio-oedema associated with the use of long-acting ACE-inhibitors, there appears to be a lack of familiarity among anaesthesiologist and other emergency physicians concerning this adverse effect. Withdrawal of the drug is the only effective treatment. High-dose steroids may be helpful, but if there is beginning dyspnoea or stridor, early endoscopically controlled intubation or emergency tracheostomy is essential to avoid hypoxaemia and death, as has occurred in the past.

[Sympathomimetic effects of low-dose S(+)-ketamine. Effect of propofol dosage].

BACKGROUND In analgetic dosages ketamine has stimulatory effects on the cardiovascular system, which limits its use in patients with heart disease. The aim of this study was to clarify whether low-dose S(+)-ketamine used to prevent chronic pain similarly stimulates the cardiovascular system and to determine the impact of propofol dosage on this effect. METHODS A total of 80 patients undergoing surgery under spinal or epidural anesthesia were randomly assigned to receive double-blinded S(+)-ketamine [0.25 mg/kg body weight (BW) bolus followed by infusion of 0.06 mg/kg BW/h] or placebo in the presence of continuous propofol infusion (2-5 mg/kg BW/h). The heart rate, blood pressure and calculated rate-pressure product (RPP) were monitored. RESULTS Following the S(+)-ketamine bolus, the heart rate, blood pressure and RPP increased significantly. In the presence of a propofol dosage >3 mg/kg BW/h the stimulatory cardiovascular effect could no longer be observed. CONCLUSION Even low-dose S(+)-ketamine has a stimulatory effect on the cardiovascular system. This stimulatory effect is nullified in the presence of a continuous propofol infusion at a dosage of more than 3 mg/kg BW/h.

[Wound infiltration with bupivacaine following pelviscopy does not reduce postoperative pain intensity. Results of a placebo-controlled, double-blind study].

Zusammenfassung. In einer doppelblind-randomisierten Studie wurde die Bauchwand bei jeweils 30 Patientinnen an den Trokar-Einstichstellen bei einer Pelviskopie entweder mit Bupivacain 0,5% oder einem Plazebo (NaCl 0,9%) infiltriert. Die Schmerztherapie erfolgte mittels PCA (Tramadol). Nach beiden Verfahren war die postoperative Schmerzintensität in den ersten 8 Stunden und am Ende des Operationstages vergleichbar. In beiden Gruppen waren die Wundschmerzen im Bereich der Einstichstellen im Vergleich zu den viszeralen Schmerzen geringer. Auch hinsichtlich der Zahl der geforderten und applizierten Analgetika-Boli sowie der kumulativen Tramadoldosis über 8 und 24 Stunden ergab sich kein Vorteil für die Infiltration mit Bupivacain. Eine routinemäßige intraoperative Infiltration mit Bupivacain führt somit weder zu einer besseren Analgesie, noch vermindert sie den Opioidbedarf. Diese Untersuchung bestätigte erneut, daß die Mehrzahl der Patientinnen nach abdominellen endoskopischen Eingriffen in der frühen postoperativen Phase (78%) einer Opioidmedikation bedarf, wobei sich die PCA angesichts der großen interindividuellen Variabilität als besonders geeignetes Verfahren erwies.Abstract. The analgetic efficacy of intraoperative infiltration with bupivacaine 0.5% or saline of the skin incisions for the endoscopic trocars was examined in 30 female patients following operative endoscopic pelviscopy in a double-blind study. Infiltration of the peritoneum, abdominal wall, and subcutaneously was performed by endoscopic view before skin suture. There were no significant differences between the two groups in age, duration of surgery, operative technique, intensity of preoperative acute and chronic pain, or state of anxiety. Postoperative pain assessment was performed using a numeric rating scale (NRS) hourly within the first 8 h and after 24 h postoperatively. After 8 h patients were asked for the localisation and description of the worst pain. Cumulative tramadol doses were calculated for 3, 8 and 24 h using patient-controlled analgesia (PCA). Pain intensity within the first 8 h postoperatively did not differ between the bupivacaine and placebo groups (Fig. 1). The mean NRS after bupivacaine infiltration was 4.6 (±2.4) in the 1st – 3rd h and 3.4 (±1.8) after 6 – 8 h (placebo: 4.8 (±2) and 2.4 (±1.7)). In both groups most patients reported lower (40%) or upper (12%) abdominal visceral pain as their worst pain. Pain due to skin incision was noted less, but in equal numbers in both groups. Of the patients in the bupivacaine group 77% and in the control group 80% started with PCA due to increasing pain scores within 60 to 120 min. The numbers of tramadol demands and given doses did not differ (Fig. 2). Therefore, intraoperative infiltration of the abdominal wall and skin with bupivacaine cannot be recommended for postoperative pain therapy after pelviscopy. Pain involving visceral afferents seems to play the major role following abdominal endoscopic surgery. In addition, the study supports recent reports showing that even after minimal invasive surgery most patients need opioids in the early postoperative period.