Christian Arndt

Incidence and duration of residual paralysis at the end of surgery after multiple administrations of cisatracurium and rocuronium

In a randomised, controlled, double‐blind, multicentre trial in 338 patients, we assessed the incidence of residual paralysis following administration of cisatracurium or rocuronium. The incidence at the end of surgery was significantly lower in patients treated with rocuronium (62 of 142 patients, 44%) than in those given cisatracurium (99 of 175 patients, 57%) (p < 0.05). In contrast, with rocuronium the mean (SD) time between skin closure and extubation was 28 (28) min vs 18 (19) min for cisatracurium, and the duration 0.9 (time from administration of last top‐up dose to recovery of the train‐of‐four ratio to 0.9) was significantly longer and more variable for rocuronium than for cisatracurium. Thus, after repeated administration, the duration and variability of duration of action are greater with rocuronium compared with cisatracurium. These pharmacodynamic differences do not necessarily translate into a higher incidence of residual paralysis, because clinicians compensate for the longer duration of action and variability of rocuronium by terminating administration of the neuromuscular blocking earlier.

The reliability and validity of the upper lip bite test compared with the Mallampati classification to predict difficult laryngoscopy: an external prospective evaluation.

Recently, a new bedside screening test to predict the occurrence of a difficult laryngoscopy has been developed as a substitute for the Mallampati classification. The Upper-Lip-Bite test (ULBT) evaluated the patient’s ability to reach or completely cover the upper lip with the lower incisors. It is often accepted that new predictive tools should undergo an external evaluation before the tool is used in clinical practice. Thus, we evaluated this test with respect to applicability, interobserver reliability, and discriminating power and compared it with the Mallampati-score (using Samsoon and Young’s modification). The ULBT could not be applied in 12% of all patients (Mallampati score, <1%). However, the interobserver reliability was better for the ULBT (&kgr; = 0.79 versus &kgr; = 0.59). The discriminating power to predict a patient with difficult laryngoscopy was evaluated in 1425 consecutive patients. Both tests were assessed simultaneously in these patients by two specially trained independent observers. After the induction of anesthesia, the laryngoscopic view was assessed by the attending anesthesiologist using the classification of Cormack and Lehane. A grade I or II was called easy laryngoscopy and grade III and IV difficult laryngoscopy. The discriminating power for both tests was low (0.60 for the ULBT [95% confidence interval, 0.57–0.63] and 0.66 [0.63–0.69]) for the Mallampati score), indicating that both tests are poor predictors as single screening tests.

A simplified risk score to predict difficult intubation: development and prospective evaluation in 3763 patients.

Background and objective Despite the presence of numerous preoperative tests to predict a difficult airway, there is no reliable bedside method. The aim of this study was to create and verify a simplified risk model with an acceptable discriminating power. Methods A total of 3763 patients from two university hospitals were screened for potential risk factors for difficult intubation, defined as needing additional technical or human resources, more than three attempts or duration more than 10 min. A random sample (n = 2509) was subjected to multivariate stepwise logistic regression analysis, and the most powerful independent risk factors were used to build a simplified model that was applied to a validation dataset (n = 1254). Results The following factors (odds ratio) were associated with a difficult intubation: presence of upper front teeth (3.61), history of difficult intubation (2.88), any Mallampati status different from ‘1’ (2.55) or equal to ‘4’ (1.91) and mouth opening less than 4 cm (1.80). The discriminating power of the score was 0.72 (95% confidence interval 0.63–0.81). The likelihood for a difficult intubation increases continuously from 0 (when no risk factor is present) to 2, 4, 8 and 17%, when one, two, three and more than three factors are present. Conclusion The new simplified multivariate risk score for difficult intubation may prove to be useful in clinical practice for predicting a difficult airway. Presence of upper front teeth, a history of difficult intubation, any Mallampati status different from ‘1’ and equal to ‘4’ and mouth opening less than 4 cm are independent risk factors for difficult endotracheal intubation. With each of these risk factors, the likelihood increases from 0 (when no risk factor is present) to 17% (when four or five factors are present).

The addition of dexamethasone to dolasetron or haloperidol for treatment of established postoperative nausea and vomiting.

It is not known whether dexamethasone increases the effectiveness of anti‐emetics when given to treat postoperative nausea and vomiting (PONV). In a randomised study, 242 patients who were experiencing PONV received dolasetron and placebo, haloperidol and placebo, dolasetron and dexamethasone, or haloperidol and dexamethasone. The results from 228 patients were suitable for analysis. PONV recurred significantly less frequently in patients treated with additional dexamethasone (33%) than in patients treated without additional dexamethasone (51%). The combination of dexamethasone with dolasetron or dexamethasone with haloperidol is superior to dolasetron or haloperidol alone for the treatment of PONV.

Postoperative analgesia with parecoxib, acetaminophen, and the combination of both: a randomized, double-blind, placebo-controlled trial in patients undergoing thyroid surgery

BACKGROUND We assessed the analgesic efficacy of parecoxib, acetaminophen, and the combination of both compared with placebo in patients undergoing elective thyroid or parathyroid surgery. METHODS We randomized 140 patients to receive one of the following i.v. treatments using a double-blinded double-dummy technique: placebo, 80 mg 24 h(-1) parecoxib, 5 g 24 h(-1) acetaminophen, or 80 mg parecoxib plus 5 g acetaminophen. We provided rescue analgesia with piritramide delivered by a patient-controlled analgesia device. We measured opioid consumption and pain intensity over 24 h after operation. RESULTS Patient characteristic data, anaesthetic, and surgical characteristics of the patients in the four groups were similar. Parecoxib, acetaminophen, and the combination significantly reduced opioid requirements during 24 h after surgery [mean (sd) 12.5 (10.9) mg for parecoxib, 14.2 (12.3) mg for acetaminophen, and 11.9 (10.7) mg for combination] compared with placebo [23.5 (15.3) mg, P<0.05]. However, the combination of parecoxib and acetaminophen did not have any advantage over individual drugs in terms of opioid consumption in our trial (P>0.05). CONCLUSIONS Parecoxib and acetaminophen effectively reduce postoperative opioid requirements after thyroid or parathyroid surgery. The combination of these drugs is not associated with a further reduction in opioid consumption.

Hypoxemia after general anesthesia

ZusammenfassungHintergrundStudien aus den Zeiten der klinischen Einführung der Pulsoxymetrie zeigten, dass nach Allgemeinanästhesien ein großer Anteil der Patienten auf dem Weg vom OP in den Aufwachraum (AWR) unter Atmung von Raumluft hypoxämisch [pulsoxymetrisch gemessene Sauerstoffsättigung (SpO2) < 90%] war und dass das Erkennen der Hypoxämie anhand von klinischen Kriterien sehr unzuverlässig ist. Unklarheit besteht darüber, ob die Inzidenz von Hypoxämien trotz modernerer Anästhesieverfahren immer noch so hoch ist, ob sich die Unzuverlässigkeit der Detektion von Hypoxämien nach klinischen Kriterien bestätigt und was die Risikofaktoren für Hypoxämien nach Allgemeinanästhesie sind.MethodenBei 970 in Allgemeinanästhesie operierten Patienten wurde nach dem Transport vom OP in den AWR unter Atmung von Raumluft die SpO2 gemessen, nachdem der betreuende Anästhesist eine Schätzung der SpO2 vorgenommen hatte. Zusammenhänge zwischen biometrischen, operativen und anästhesiologischen Variablen einerseits sowie Hypoxämie andererseits wurden multivariat untersucht.ErgebnisseEs hatten 17% der 959 ausgewerteten Patienten eine SpO2 < 90%; hierbei wiesen 6,6% der Patienten eine SpO2 < 85% auf. Die Hypoxämie wurde in 82% der Fälle nicht erkannt. Unabhängige Einflussfaktoren auf eine Hypoxämie waren: Ausgangssättigung, Body-Mass-Index, Alter, körperlicher Status gemäß Klassifikation der American Society of Anesthesiologists, Differenz zwischen maximalem und minimalem Beatmungsdruck, Beatmungsmodus, Wahl des Opioids, des Relaxans und Verwendung von Lachgas.SchlussfolgerungDurch die Wahl von Anästhetika können Hypoxämien und Sättigungsabfälle günstig beeinflusst werden, ohne dass dadurch diese Problematik vollständig gelöst werden kann, weil die stärksten Risikofaktoren patientenassoziiert sind. Da bislang selbst bei Kenntnis von Risikofaktoren nicht vorherzusagen ist, wer nach Allgemeinanästhesie eine SpO2 < 90% haben wird und überdies die Abschätzung der SpO2 anhand klinischer Kriterien höchst unzuverlässig ist, erscheint der Transport von spontan-atmenden Patienten nach Narkose ohne Überwachung der SpO2 bzw. ohne O2-Gabe überdenkenswert.AbstractBackgroundStudies conducted shortly after the implementation of pulse oximetry (PO) into clinical practice 20–25 years ago revealed that many patients breathing room air during transfer from the operating room (OR) to the post-anesthesia care unit (PACU) directly after general anesthesia (GA) had a peripheral oxygen saturation (SpO2) below 90%. Moreover, it was shown that the detection of hypoxemia by clinical criteria is extremely unreliable. Meanwhile, the use of PO has become part of the obligatory standard monitoring during GA in Germany and many other countries. Likewise, the use of PO is standard care in the PACU although there are no official recommendations. However, for the time period in between, i.e. immediately after GA during transportation of patients from the OR to the PACU, monitoring of the SpO2 in patients breathing room air is neither obligatory in Germany nor are there any official recommendations or guidelines in this respect. Given the introduction of shorter acting anesthetic agents within the last 25 years, the main goal of this study was to explore whether the incidence of hypoxemia in the immediate period after GA is still so high. Additional aims of this study were to examine whether the detection of hypoxemia based on clinical criteria can be confirmed to be very unreliable, what the risk factors for hypoxemia following GA are and how common it is in Germany to transport patients from the OR to the PACU without PO and supplemental oxygen.MethodsIn a prospective observational study 970 patients who underwent a broad spectrum of elective surgery under GA in a university hospital setting were included. The SpO2 was measured at the end of the transfer from the OR to the PACU immediately after the anesthetist who had taken care of the patient during the operation had estimated the SpO2. The association between biometric, surgical and anesthesiological variables on the one hand and hypoxemia as well as a decrease of SpO2 on the other hand were studied using multivariate methods. Finally, a survey including all university hospitals was carried out to find out about the use of PO and oxygen during patient transfer from the OR to the PACU.ResultsOf the 959 patients who were eligible for analysis 17% had a SpO2 < 90% and 6.6% a SpO2 < 85%. Hypoxemia was not recognized in 82% of the patients in whom an assessment based on clinical grounds was carried out. Variables with an independent influence on hypoxemia and decrease of SpO2 were as follows: saturation before induction of GA, body mass index, age, American Society of Anesthesiologists (ASA) physical status, difference between maximum and minimum inspiratory pressure, mode of ventilation, the choice of opioid and muscle relaxant as well as the use of nitrous oxide. Patient-dependent risk factors had the strongest impact on hypoxemia. In about 80% of the university hospitals neither PO nor supplemental oxygen is used during transportation of the patient from the OR to the PACU.ConclusionsThe use of opioids and relaxants with short duration of action may have favorable effects on preventing hypoxemia and decreases of SpO2. These measures will, however, not be sufficient to solve this problem because the highest risk factors for hypoxemia are patient-related. Despite knowing risk factors for oxygen desaturation, it is currently not possible to reliably predict which patients will become hypoxemic or have a decrease of SpO2. Therefore, transportation of patients breathing room air from the OR to the PACU directly after GA without use of PO or supplemental oxygen seems to be questionable in terms of patient safety.BACKGROUND Studies conducted shortly after the implementation of pulse oximetry (PO) into clinical practice 20-25 years ago revealed that many patients breathing room air during transfer from the operating room (OR) to the post-anesthesia care unit (PACU) directly after general anesthesia (GA) had a peripheral oxygen saturation (S(p)O(2)) below 90%. Moreover, it was shown that the detection of hypoxemia by clinical criteria is extremely unreliable. Meanwhile, the use of PO has become part of the obligatory standard monitoring during GA in Germany and many other countries. Likewise, the use of PO is standard care in the PACU although there are no official recommendations. However, for the time period in between, i.e. immediately after GA during transportation of patients from the OR to the PACU, monitoring of the S(p)O(2) in patients breathing room air is neither obligatory in Germany nor are there any official recommendations or guidelines in this respect. Given the introduction of shorter acting anesthetic agents within the last 25 years, the main goal of this study was to explore whether the incidence of hypoxemia in the immediate period after GA is still so high. Additional aims of this study were to examine whether the detection of hypoxemia based on clinical criteria can be confirmed to be very unreliable, what the risk factors for hypoxemia following GA are and how common it is in Germany to transport patients from the OR to the PACU without PO and supplemental oxygen. METHODS In a prospective observational study 970 patients who underwent a broad spectrum of elective surgery under GA in a university hospital setting were included. The S(p)O(2) was measured at the end of the transfer from the OR to the PACU immediately after the anesthetist who had taken care of the patient during the operation had estimated the S(p)O(2). The association between biometric, surgical and anesthesiological variables on the one hand and hypoxemia as well as a decrease of S(p)O(2) on the other hand were studied using multivariate methods. Finally, a survey including all university hospitals was carried out to find out about the use of PO and oxygen during patient transfer from the OR to the PACU. RESULTS Of the 959 patients who were eligible for analysis 17% had a S(p)O(2) < 90% and 6.6% a S(p)O(2) < 85%. Hypoxemia was not recognized in 82% of the patients in whom an assessment based on clinical grounds was carried out. Variables with an independent influence on hypoxemia and decrease of S(p)O(2) were as follows: saturation before induction of GA, body mass index, age, American Society of Anesthesiologists (ASA) physical status, difference between maximum and minimum inspiratory pressure, mode of ventilation, the choice of opioid and muscle relaxant as well as the use of nitrous oxide. Patient-dependent risk factors had the strongest impact on hypoxemia. In about 80% of the university hospitals neither PO nor supplemental oxygen is used during transportation of the patient from the OR to the PACU. CONCLUSIONS The use of opioids and relaxants with short duration of action may have favorable effects on preventing hypoxemia and decreases of S(p)O(2). These measures will, however, not be sufficient to solve this problem because the highest risk factors for hypoxemia are patient-related. Despite knowing risk factors for oxygen desaturation, it is currently not possible to reliably predict which patients will become hypoxemic or have a decrease of S(p)O(2). Therefore, transportation of patients breathing room air from the OR to the PACU directly after GA without use of PO or supplemental oxygen seems to be questionable in terms of patient safety.

Hypernatriämie – Diagnostik und Therapie

Hypernatremia is a common electrolyte disorder that reflects an imbalance in the water balance of the body, often resulting from an increased loss of free water compared to sodium excretion. It is rarely based on excessive sodium intake. The clinical presentation is often characterized by a central nervous system dysfunction (confusion, coma) and pronounced thirst (in awake patients). In addition to medical history, the volume status of the patient and the osmolality of urine are leading in the differential diagnosis. Usually, the treatment of hypernatremia - in addition to addressing the underlying cause - is replacing the (absolute or relative) loss of free water by hypotonic infusions, or in case of diabetes insipidus, by application of Desmopressin (Minirin). As rapid changes in serum sodium concentration may have deleterious consequences (osmotic demyelinsiation syndrome), preexisting hypernatremia (>48h) should not be reduced by more than 8-10 mmol/l/day. Close laboratory controls are important. For acute hypernatremia (< 24 hours), hemodialysis is an effective option to rapidly normalize the serum sodium levels. To avoid a rapid drop in sodium concentration that must also be considered when starting a renal replacement therapy in patients with chronic hypernatremia.

Hypoxämie nach Allgemeinanästhesie@@@Hypoxemia after general anesthesia

ZusammenfassungHintergrundStudien aus den Zeiten der klinischen Einführung der Pulsoxymetrie zeigten, dass nach Allgemeinanästhesien ein großer Anteil der Patienten auf dem Weg vom OP in den Aufwachraum (AWR) unter Atmung von Raumluft hypoxämisch [pulsoxymetrisch gemessene Sauerstoffsättigung (SpO2) < 90%] war und dass das Erkennen der Hypoxämie anhand von klinischen Kriterien sehr unzuverlässig ist. Unklarheit besteht darüber, ob die Inzidenz von Hypoxämien trotz modernerer Anästhesieverfahren immer noch so hoch ist, ob sich die Unzuverlässigkeit der Detektion von Hypoxämien nach klinischen Kriterien bestätigt und was die Risikofaktoren für Hypoxämien nach Allgemeinanästhesie sind.MethodenBei 970 in Allgemeinanästhesie operierten Patienten wurde nach dem Transport vom OP in den AWR unter Atmung von Raumluft die SpO2 gemessen, nachdem der betreuende Anästhesist eine Schätzung der SpO2 vorgenommen hatte. Zusammenhänge zwischen biometrischen, operativen und anästhesiologischen Variablen einerseits sowie Hypoxämie andererseits wurden multivariat untersucht.ErgebnisseEs hatten 17% der 959 ausgewerteten Patienten eine SpO2 < 90%; hierbei wiesen 6,6% der Patienten eine SpO2 < 85% auf. Die Hypoxämie wurde in 82% der Fälle nicht erkannt. Unabhängige Einflussfaktoren auf eine Hypoxämie waren: Ausgangssättigung, Body-Mass-Index, Alter, körperlicher Status gemäß Klassifikation der American Society of Anesthesiologists, Differenz zwischen maximalem und minimalem Beatmungsdruck, Beatmungsmodus, Wahl des Opioids, des Relaxans und Verwendung von Lachgas.SchlussfolgerungDurch die Wahl von Anästhetika können Hypoxämien und Sättigungsabfälle günstig beeinflusst werden, ohne dass dadurch diese Problematik vollständig gelöst werden kann, weil die stärksten Risikofaktoren patientenassoziiert sind. Da bislang selbst bei Kenntnis von Risikofaktoren nicht vorherzusagen ist, wer nach Allgemeinanästhesie eine SpO2 < 90% haben wird und überdies die Abschätzung der SpO2 anhand klinischer Kriterien höchst unzuverlässig ist, erscheint der Transport von spontan-atmenden Patienten nach Narkose ohne Überwachung der SpO2 bzw. ohne O2-Gabe überdenkenswert.AbstractBackgroundStudies conducted shortly after the implementation of pulse oximetry (PO) into clinical practice 20–25 years ago revealed that many patients breathing room air during transfer from the operating room (OR) to the post-anesthesia care unit (PACU) directly after general anesthesia (GA) had a peripheral oxygen saturation (SpO2) below 90%. Moreover, it was shown that the detection of hypoxemia by clinical criteria is extremely unreliable. Meanwhile, the use of PO has become part of the obligatory standard monitoring during GA in Germany and many other countries. Likewise, the use of PO is standard care in the PACU although there are no official recommendations. However, for the time period in between, i.e. immediately after GA during transportation of patients from the OR to the PACU, monitoring of the SpO2 in patients breathing room air is neither obligatory in Germany nor are there any official recommendations or guidelines in this respect. Given the introduction of shorter acting anesthetic agents within the last 25 years, the main goal of this study was to explore whether the incidence of hypoxemia in the immediate period after GA is still so high. Additional aims of this study were to examine whether the detection of hypoxemia based on clinical criteria can be confirmed to be very unreliable, what the risk factors for hypoxemia following GA are and how common it is in Germany to transport patients from the OR to the PACU without PO and supplemental oxygen.MethodsIn a prospective observational study 970 patients who underwent a broad spectrum of elective surgery under GA in a university hospital setting were included. The SpO2 was measured at the end of the transfer from the OR to the PACU immediately after the anesthetist who had taken care of the patient during the operation had estimated the SpO2. The association between biometric, surgical and anesthesiological variables on the one hand and hypoxemia as well as a decrease of SpO2 on the other hand were studied using multivariate methods. Finally, a survey including all university hospitals was carried out to find out about the use of PO and oxygen during patient transfer from the OR to the PACU.ResultsOf the 959 patients who were eligible for analysis 17% had a SpO2 < 90% and 6.6% a SpO2 < 85%. Hypoxemia was not recognized in 82% of the patients in whom an assessment based on clinical grounds was carried out. Variables with an independent influence on hypoxemia and decrease of SpO2 were as follows: saturation before induction of GA, body mass index, age, American Society of Anesthesiologists (ASA) physical status, difference between maximum and minimum inspiratory pressure, mode of ventilation, the choice of opioid and muscle relaxant as well as the use of nitrous oxide. Patient-dependent risk factors had the strongest impact on hypoxemia. In about 80% of the university hospitals neither PO nor supplemental oxygen is used during transportation of the patient from the OR to the PACU.ConclusionsThe use of opioids and relaxants with short duration of action may have favorable effects on preventing hypoxemia and decreases of SpO2. These measures will, however, not be sufficient to solve this problem because the highest risk factors for hypoxemia are patient-related. Despite knowing risk factors for oxygen desaturation, it is currently not possible to reliably predict which patients will become hypoxemic or have a decrease of SpO2. Therefore, transportation of patients breathing room air from the OR to the PACU directly after GA without use of PO or supplemental oxygen seems to be questionable in terms of patient safety.BACKGROUND Studies conducted shortly after the implementation of pulse oximetry (PO) into clinical practice 20-25 years ago revealed that many patients breathing room air during transfer from the operating room (OR) to the post-anesthesia care unit (PACU) directly after general anesthesia (GA) had a peripheral oxygen saturation (S(p)O(2)) below 90%. Moreover, it was shown that the detection of hypoxemia by clinical criteria is extremely unreliable. Meanwhile, the use of PO has become part of the obligatory standard monitoring during GA in Germany and many other countries. Likewise, the use of PO is standard care in the PACU although there are no official recommendations. However, for the time period in between, i.e. immediately after GA during transportation of patients from the OR to the PACU, monitoring of the S(p)O(2) in patients breathing room air is neither obligatory in Germany nor are there any official recommendations or guidelines in this respect. Given the introduction of shorter acting anesthetic agents within the last 25 years, the main goal of this study was to explore whether the incidence of hypoxemia in the immediate period after GA is still so high. Additional aims of this study were to examine whether the detection of hypoxemia based on clinical criteria can be confirmed to be very unreliable, what the risk factors for hypoxemia following GA are and how common it is in Germany to transport patients from the OR to the PACU without PO and supplemental oxygen. METHODS In a prospective observational study 970 patients who underwent a broad spectrum of elective surgery under GA in a university hospital setting were included. The S(p)O(2) was measured at the end of the transfer from the OR to the PACU immediately after the anesthetist who had taken care of the patient during the operation had estimated the S(p)O(2). The association between biometric, surgical and anesthesiological variables on the one hand and hypoxemia as well as a decrease of S(p)O(2) on the other hand were studied using multivariate methods. Finally, a survey including all university hospitals was carried out to find out about the use of PO and oxygen during patient transfer from the OR to the PACU. RESULTS Of the 959 patients who were eligible for analysis 17% had a S(p)O(2) < 90% and 6.6% a S(p)O(2) < 85%. Hypoxemia was not recognized in 82% of the patients in whom an assessment based on clinical grounds was carried out. Variables with an independent influence on hypoxemia and decrease of S(p)O(2) were as follows: saturation before induction of GA, body mass index, age, American Society of Anesthesiologists (ASA) physical status, difference between maximum and minimum inspiratory pressure, mode of ventilation, the choice of opioid and muscle relaxant as well as the use of nitrous oxide. Patient-dependent risk factors had the strongest impact on hypoxemia. In about 80% of the university hospitals neither PO nor supplemental oxygen is used during transportation of the patient from the OR to the PACU. CONCLUSIONS The use of opioids and relaxants with short duration of action may have favorable effects on preventing hypoxemia and decreases of S(p)O(2). These measures will, however, not be sufficient to solve this problem because the highest risk factors for hypoxemia are patient-related. Despite knowing risk factors for oxygen desaturation, it is currently not possible to reliably predict which patients will become hypoxemic or have a decrease of S(p)O(2). Therefore, transportation of patients breathing room air from the OR to the PACU directly after GA without use of PO or supplemental oxygen seems to be questionable in terms of patient safety.