D. Rüsch

Nausea and Vomiting After Surgery Under General Anesthesia: An Evidence-Based Review Concerning Risk Assessment, Prevention, and Treatment

BACKGROUND The German-language recommendations for the management of postoperative nausea and vomiting (PONV) have been revised by an expert committee. Major aspects of this revision are presented here in the form of an evidence-based review article. METHODS The literature was systematically reviewed with the goal of revising the existing recommendations. New evidence-based recommendations for the management of PONV were developed, approved by consensus, and graded according to the scheme of the Scottish Intercollegiate Guidelines Network (SIGN). RESULTS The relevant risk factors for PONV include female sex, nonsmoker status, prior history of PONV, motion sickness, use of opioids during and after surgery, use of inhalational anesthetics and nitrous oxide, and the duration of anesthesia. PONV scoring systems provide a rough assessment of risk that can serve as the basis for a risk-adapted approach. Risk-adapted prophylaxis, however, has not been shown to provide any greater benefit than fixed (combination) prophylaxis, and PONV risk scores have inherent limitations; thus, fixed prophylaxis may be advantageous. Whichever of these two approaches to manage PONV is chosen, high-risk patients must be given multimodal prophylaxis, involving both the avoidance of known risk factors and the application of multiple validated and effective antiemetic interventions. PONV should be treated as soon as it arises, to minimize patient discomfort, the risk of medical complications, and the costs involved. CONCLUSION PONV lowers patient satisfaction but is treatable. The effective, evidence-based measures of preventing and treating it should be implemented in routine practice.

Prospective application of a simplified risk score to prevent postoperative nausea and vomiting.

PurposeTo compare the risk-adapted approach with ondansetron against ondansetron plus dexamethasone to prevent postoperative nausea and vomiting (PONV) in a randomized clinical trial.Methods460 patients scheduled for elective surgery were enrolled in this prospective study and stratified according to a simplified risk score for PONV. Patients having no or one risk factor were considered at low risk (group L) and did not receive study medication. Those with two to four risk factors were considered high risk and were randomized to receive 4 mg ondansetron plus placebo (group H-O) or 4 mg ondansetron plus 8 mg dexamethasone (group H-OD). Incidence and intensity of PONV were observed for 24 hr after surgery. Data were analyzed with Fisher’s exact or Student’s t tests;P < 0.05 was considered statistically significant.ResultsThe incidence of PONV was 9% in group L (n = 87), 31% in those receiving ondansetron (group H-O,n = 185), and 22% in those receiving both drugs (group H-OD,n = 181). The incidence of PONV was significantly smaller in both high-risk groups than predicted without treatment (P < 0.001). While the incidence of PONV failed statistical significance between the two intervention groups (P = 0.08), the mean number of episodes of PONV and the mean maximal intensity of each episode of PONV were lower in group H-OD (P = 0.03 andP = 0.01, respectively). Patients of group H-OD required less antiemetic rescue therapy (P = 0.004). Conclusions: Ondansetron plus dexamethasone prevents PONV more effectively than ondansetron alone in patients at high risk for PONV.RésuméObjectifComparer l’approche adaptée au risque avec ondansétron ou avec ondansétron et dexaméthasone pour prévenir les nausées et vomissements postopératoires (NVPO) dans une étude clinique randomisée.MéthodeL’étude prospective a porté sur 460 patients, devant subir une intervention chirurgicale réglée, qui ont été stratifiés selon un score de risque simplifié de NVPO. Les patients ont été considérés à faible risque (groupe F) s’ils n’avaient aucun ou un facteur de risque et n’ont pas reçu la médication à l’étude. S’ils avaient de deux à quatre facteurs de risque, on les considérait à haut risque et ils recevaient au hasard 4 mg d’ondansétron plus un placebo (groupe H-O) ou 4 mg d’ondansétron plus 8 mg de dexaméthasone (groupe H-OD). L’incidence et l’intensité des NVPO ont été observées pendant 24 h après l’opération. Les données ont été analysées par les tests exact de Fisher ou t de Student ; P < 0,05 était statistiquement significatif.RésultatsL’incidence de NVPO a été de 9 % dans le groupe F (n = 87), 31 % avec l’ondansétron (groupe H-O, n = 185) et 22 % avec les deux médicaments (groupe H-OD, n = 181). L’incidence de NVPO a été significativement plus basse dans les deux groupes à haut risque que ce qui avait été prédit sans traitement (P < 0,001). Même si l’incidence de NVPO n’était pas statistiquement significative entre les deux groupes expérimentaux (P = 0,08), le nombre moyen d’épisodes de NVPO et l’intensité maximale moyenne de chacun ont été plus faibles dans le groupe H-OD (P = 0,03 et P = 0,01, respectivement). Les patients du groupe H-OD ont demandé moins d’antiémétiques de secours P = 0,004).ConclusionL’ondansétron plus la dexaméthasone préviennent les NVPO plus efficacement que l’ondansétron seul chez des patients à haut risque de NVPO.

Coping strategies in anxious surgical patients

BackgroundAnaesthesia and surgery provoke preoperative anxiety and stress. Patients try to regain control of their emotions by using coping efforts. Coping may be more effective if supported by specific strategies or external utilities. This study is the first to analyse coping strategies in a large population of patients with high preoperative anxiety.MethodsWe assessed preoperative anxiety and coping preferences in a consecutive sample of 3087 surgical patients using validated scales (Amsterdam Preoperative Anxiety and Information Scale/Visual Analogue Scale). In the subsample of patients with high preoperative anxiety, patients’ dispositional coping style was determined and patients’ coping efforts were studied by having patients rate their agreement with 9 different coping efforts on a four point Likert scale. Statistical analysis included correlational analysis between dispositional coping styles, coping efforts and other variables such as sociodemographic data. Statistical significance was considered for p < 0.05.ResultsThe final analysis included 1205 patients with high preoperative anxiety. According to the initial self-assessment, about two thirds of the patients believed that information would help them to cope with their anxiety (“monitors”); the remainder declined further education/information and reported self-distraction to be most helpful to cope with anxiety (“blunters”). There was no significant difference between these two groups in anxiety scores.Educational conversation was the coping effort rated highest in monitors whereas calming conversation was the coping effort rated highest in blunters. Coping follows no demographic rules but is influenced by the level of education. Anxiolytic Medication showed no reliable correlation to monitoring and blunting disposition. Both groups showed an exactly identical agreement with this coping effort.Demand for medical anxiolysis, blunting or the desire for more conversation may indicate increased anxiety. The use of the internet was independent of the anxiety level and the demand of information.ConclusionConversation with medical staff proved to be the most popular coping strategy. Acknowledgment of the division between information-seeking and blunting-like personalities is central to supporting the patient’s individual coping efforts. Internet access may be the easiest way to support coping today.

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.

Hypoxämie nach Allgemeinanästhesie

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.

[Prophylaxis of nausea and vomiting in the postoperative phase: relative effectiveness of droperidol and metoclopramide].

OBJECTIVE The aim of the present study was to conduct a meta-analysis of the results from randomized controlled trials investigating the relative efficacy of droperidol versus metoclopramide for the prevention of postoperative nausea and vomiting (PONV). METHODS A systematic literature search for randomized controlled trials comparing droperidol and metoclopramide for the prevention of PONV was performed according to the PRISMA recommendations. The incidence of PONV within the early (0-6 h) and cumulative postoperative periods (0-48 h) was collated and the pooled relative risk (RR) with the corresponding 95% confidence interval (CI) was calculated. Results from a subgroup analysis are presented excluding the data of a Japanese group (Fujii et al.) which are given in parentheses. RESULTS A total of 41 (30) trials with a total number of 3,491 (2,721) patients were included and of these 12 (8) trials with 1,403 (1,083) patients reported data of the early period and 32 (21) studies with 2,656 (1,836) patients comprised data of the cumulative period. A total of 1,797 (1,309) patients were treated with droperidol (0.25-5 mg) and 1,694 (1,412) with metoclopramide (5-50 mg). In the early period the risk for PONV after metoclopramide was 35% (95%-CI: 17-57%) higher than after prophylaxis with droperidol (without Fujii data: 46%; 23-73%). During the cumulative period the risk for PONV after metoclopramide was increased by 20% (95%-CI: 7-37%) compared to droperidol (without Fujii data: 25%; 4-50%). Due to heterogenous dosing of both drugs subgroup analyses with distinct dose intervals were performed with increments of 0.75 mg for droperidol and 7 mg for metoclopramide. Droperidol was superior in 17 (12) out of 19 (14) subgroup analyses. Comparing recommended doses of droperidol (0.75-1.5 mg) with low doses of metoclopramide (7-14 mg) and medium metoclopramide doses (14-21 mg) PONV was increased by 12% (95%-CI: -11% to 42%) and 32% (95%-CI: 4%-66%), respectively when metoclopramide instead of droperidol was used. When higher doses of metoclopramide (>20 mg) were used the superiority of droperidol was less pronounced and did not reach statistical significance due to the limited numbers of trials included in this analysis (3 studies, 662 patients). The risk for PONV after high-dose metoclopramide was increased by 13% (95%-CI: -21% to +61%) for the early period and by 19% (95%-CI: -11% to +57%) for the cumulative observation period. CONCLUSION For the prevention of postoperative nausea and vomiting droperidol is significantly superior to metoclopramide doses below 20 mg. There was no obvious positive dose response with respect to increasing doses of metoclopramide. There was also a trend towards higher efficacy of droperidol compared to higher doses of metoclopramide (≥20 mg). However, there were not enough comparative studies to show a statistically significant result in this subgroup analysis. These data support the notion that droperidol in low doses may represent the more effective D(2)-antagonist for a pharmacological armamentarium to cope with PONV.

Prophylaxe von Übelkeit und Erbrechen in der postoperativen Phase

OBJECTIVE The aim of the present study was to conduct a meta-analysis of the results from randomized controlled trials investigating the relative efficacy of droperidol versus metoclopramide for the prevention of postoperative nausea and vomiting (PONV). METHODS A systematic literature search for randomized controlled trials comparing droperidol and metoclopramide for the prevention of PONV was performed according to the PRISMA recommendations. The incidence of PONV within the early (0-6 h) and cumulative postoperative periods (0-48 h) was collated and the pooled relative risk (RR) with the corresponding 95% confidence interval (CI) was calculated. Results from a subgroup analysis are presented excluding the data of a Japanese group (Fujii et al.) which are given in parentheses. RESULTS A total of 41 (30) trials with a total number of 3,491 (2,721) patients were included and of these 12 (8) trials with 1,403 (1,083) patients reported data of the early period and 32 (21) studies with 2,656 (1,836) patients comprised data of the cumulative period. A total of 1,797 (1,309) patients were treated with droperidol (0.25-5 mg) and 1,694 (1,412) with metoclopramide (5-50 mg). In the early period the risk for PONV after metoclopramide was 35% (95%-CI: 17-57%) higher than after prophylaxis with droperidol (without Fujii data: 46%; 23-73%). During the cumulative period the risk for PONV after metoclopramide was increased by 20% (95%-CI: 7-37%) compared to droperidol (without Fujii data: 25%; 4-50%). Due to heterogenous dosing of both drugs subgroup analyses with distinct dose intervals were performed with increments of 0.75 mg for droperidol and 7 mg for metoclopramide. Droperidol was superior in 17 (12) out of 19 (14) subgroup analyses. Comparing recommended doses of droperidol (0.75-1.5 mg) with low doses of metoclopramide (7-14 mg) and medium metoclopramide doses (14-21 mg) PONV was increased by 12% (95%-CI: -11% to 42%) and 32% (95%-CI: 4%-66%), respectively when metoclopramide instead of droperidol was used. When higher doses of metoclopramide (>20 mg) were used the superiority of droperidol was less pronounced and did not reach statistical significance due to the limited numbers of trials included in this analysis (3 studies, 662 patients). The risk for PONV after high-dose metoclopramide was increased by 13% (95%-CI: -21% to +61%) for the early period and by 19% (95%-CI: -11% to +57%) for the cumulative observation period. CONCLUSION For the prevention of postoperative nausea and vomiting droperidol is significantly superior to metoclopramide doses below 20 mg. There was no obvious positive dose response with respect to increasing doses of metoclopramide. There was also a trend towards higher efficacy of droperidol compared to higher doses of metoclopramide (≥20 mg). However, there were not enough comparative studies to show a statistically significant result in this subgroup analysis. These data support the notion that droperidol in low doses may represent the more effective D(2)-antagonist for a pharmacological armamentarium to cope with PONV.

Vapocoolant Spray Versus Lidocaine Infiltration for Radial Artery Cannulation: A Prospective, Randomized, Controlled Clinical Trial

OBJECTIVES Local infiltration with lidocaine is a frequently used measure to prevent pain during arterial cannulation. Its administration is associated with pain. Vapocoolants like ethyl chloride or alkanes also affect rapid-onset anesthesia. However, their administration causes less discomfort compared with administration of lidocaine. The effectiveness of vapocoolants in mitigating discomfort associated with arterial cannulation never has been studied. The authors therefore compared vapocoolant with lidocaine for reducing discomfort caused by arterial cannulation. DESIGN Prospective, randomized, controlled study. SETTING University hospital, single center. PARTICIPANTS One hundred sixty adult patients requiring arterial cannulation before induction of general anesthesia for cardiac surgery or carotid endarterectomy. INTERVENTIONS Patients received either lidocaine infiltration or vapocoolant spray prior to arterial cannulation. Overall discomfort resulting from the whole procedure (applying local/topical anesthesia followed by arterial puncture) was rated on a 0 to 10 numerical rating scale. Puncture failure rate and time required for the intervention also were recorded. MEASUREMENTS AND MAIN RESULTS One hundred forty-three patients were included in the per-protocol analysis. Mean pain scores in the vapocoolant group were 3.4 (±1.58) compared with 4.5 (±2.29) in the lidocaine group (difference 1.1±0.33; p = 0.032; Mann-Whitney U-test). The higher puncture failure rate in the lidocaine group (n = 11 v 4) was not significant (p = 0.06; Fishers exact test). The time required for the intervention was longer in the lidocaine group (138±44 s v 128±44 s; p = 0.019; Mann-Whitney U-test). CONCLUSIONS Vapocoolant spray is an alternative to lidocaine infiltration to mitigate discomfort associated with arterial cannulation.

Pain During Venous Cannulation

BACKGROUND The pain of venous puncture for the cannulation of peripheral veins is disturbing to many patients. This is the first clinical trial of the efficacy of local anesthesia in comparison to placebo (no pretreatment) in a control group, as a function of the size of the cannula. METHODS A randomized, controlled trial of fully factorial design was performed to study pain during venipuncture after local anesthesia either with intra - dermally injected lidocaine or with a vapocoolant spray, in comparison to placebo. A standardized protocol was used for structured communication with the patient to provide the greatest feasible degree of patient blinding (trial registration number DRKS00010155). The primary endpoints were the subjective discomfort of the patient during preparation and puncture of a vein of the dorsum of the hand, assessed on a numerical rating scale (NRS) from 0 (no discomfort) to 10 (unbearable discomfort), and the rate of unsuccessful puncture. RESULTS The intention-to-treat analysis of all 450 patients revealed that the reported degree of pain during venipuncture depended to a large extent on the caliber of the chosen venous cannula. For a 17-gauge (17G) cannula, both the vapocoolant spray (NRS = 2.6 ± 1.3) and lidocaine (NRS = 3.5 ± 2.2) lessened the discomfort due to venipuncture compared to control treatment (5.0 ± 1.5). The effect of vapocoolant spray compared to the control was both clinically relevant and statistically significant (p < 0.0001). When a smaller 20G cannula was used, however, vapocoolant spray improved discomfort by only 0.8 NRS points, which, though still statistically significant (p = 0.0056), was no longer clinically relevant. The rate of unsuccessful puncture was higher after lidocaine pretreatment (12.7%) than after either vapocoolant spray (4.7%; p = 0.0066) or no pretreatment (4.0%; p = 0.0014). CONCLUSION Local anesthesia can be recommended before venipuncture only if a large cannula is used (e.g., ≥ 17G). Vapocoolant spray may be at least as useful as lidocaine injection; it prevents pain to a similar extent and is associated with a lower rate of unsuccessful puncture.

[Caesarean sections under regional anesthesia: pros and cons of supplementary oxygen].

The routine administration of supplemental oxygen to women undergoing elective caesarean section under regional anesthesia in order to optimize oxygen supply to the fetus is common anesthetic practice in many German hospitals. However, this practice has been controversially discussed in the non-German literature for many years. This review presents and discusses the pros and cons of routinely providing supplemental oxygen to a parturient during caesarean section on the basis of the literature published over the last 30 years. Proponents of routine oxygen administration point to potential and unforeseeable risks of caesarean sections and consider the prophylactic administration of oxygen based on physiological considerations to be advantageous in terms of patient safety. Interestingly, data regarding the effects of an increased maternal FIO2 on improvement of fetal oxygenation are inconsistent, therefore, no unambiguous recommendation concerning which FIO2 to choose can be given. Opponents of routine oxygen supplementation allude above all to an increase in free radical activity in both mother and fetus; however, data in this respect are not consistent either. As supplemental oxygen to patients undergoing elective caesarean section without any risk factors under regional anesthesia is associated with potential risks while no advantage has so far been demonstrated, routine administration of oxygen has to be challenged and is no longer considered to be indicated by many. On the contrary, in cases of emergency with a concomitant risk of hypoxia for mother and fetus, administration of oxygen is indispensable in the light of present data.