O desmame é a transição da ventilação mecânica para a espontânea ao final da assistência ventilatória artificial. Não existem estudos específicos sobre esta fase de transição na espécie equina porém, os elevados valores na tensão de dióxido de carbono arterial (PaCO2) ao desmame e os baixos valores na tensão de oxigênio arterial (PaO2) na recuperação pós-anestésica (RPA) refletem a necessidade do estudo de modalidades mais seguras de desmame. Sendo assim, este estudo objetivou comparar dois diferentes protocolos de desmame da ventilação mecânica em equinos hígidos. Para tanto, foram utilizados 20 equinos, de 5±2 anos de idade e pesando 456±90 kg, submetidos a procedimento cirúrgico em decúbito dorsal. Os animais foram divididos aleatoriamente em 2 grupos de acordo com o protocolo de desmame, sendo considerado Grupo Controle os animais que foram submetidos a diminuição gradual da frequência respiratória (FR) isoladamente e Grupo PSV os animais que foram submetidos à redução da FR associada à administração de pressão de suporte ventilatório (PSV). Avaliou-se os parâmetros cardiovasculares, de ventilação, de oxigenação e metabólicos durante o desmame, a desconexão da ventilação mecânica e a RPA. Ao final do desmame, o Vexp (12,49±1,93 L) e o VT (28,10±6,17 mL/kg) do Grupo PSV foram superiores aos do Grupo Controle (Vexp de 7,66±2,66 L e VT de 16,88±4,30 mL/kg). Durante o desmame, a PaCO2 aumentou 29% (de 44±3 mmHg para 57±6 mmHg) e houve diminuição de 28% da relação PaO2/FiO2 (de 391±68 mmHg para 280±28) e de 9% da SaO2 (de 100±1% para 91±3%) apenas no Grupo Controle. Na RPA houve hipoxemia transitória no Grupo Controle após 15 (PaO2 de 48±5 mmHg) e 35 minutos (PaO2 de 57±7 mmHg) da desconexão do ventilador, e no Grupo PSV obteve-ve relação PaO2/FiO2 e SaO2 superior à do Grupo Controle durante a RPA. Concluiu-se que o uso da PSV no desmame foi capaz de manter os parâmetros ventilatórios e de oxigenação adequados durante todos os momentos de avaliação, e o desmame por redução gradativa da FR não impediu a ocorrência de hipercapnia transitória ao final do desmame e hipoxemia transitória na RPA. Considerando-se a higidez dos animais, estas alterações foram revertidas sem intervenção clínica, mas devem ser consideradas em animais debilitados. / Weaning from mechanical ventilation is the transition from mechanical to spontaneous ventilation at the end of the ventilatory support. There are no specific studies about this transition phase in horses. However, high tension of carbon dioxide pressure (PaCO2) at weaning and low values of arterial oxygen tension (PaO2) during recovery from anaesthesia suggest the need to study safer modalities of weaning. The scope of this study was to compare two weaning protocols from mechanical ventilation in healthy horses. With this purpose we studied 20 horses with a mean age of 5±2 years and a mean weight of 456±90 kg, scheduled to surgery in dorsal recumbency. Animals were randomly assigned one of the 2 weaning protocols, considering from Control Group those animals submitted to gradual decrease in respiratory rate (RR) set alone and from PSV Group those animals submitted to gradual decrease in RR associated with pressure support ventilation (PSV) administration. We evaluated cardiovascular, ventilatory, oxygenation and metabolic parameters during weaning, ventilator disconnection and recovery from anaesthesia. At the end of weaning, Vexp (12,49±1,93 L) and VT (28,10±6,17 mL/kg) of PSV Group were superior to the Control Group (Vexp of 7.66±2.66 L and VT of 16.88±4.30 mL/kg). During weaning PaCO2 increased by 29% (44±3 mmHg to 57±6 mmHg) and there was increasing PaO2/FiO2 ratio by 28% (391±68 mmHg to 280±28) and SaO2 by 9% (100±1% to 91±3%) only in Control Group. In the recovery phase there was transient hypoxemia in Control Group after 15 (PaO2 of 48±5 mmHg) and 35 minutes (PaO2 of 57±7 mmHg) of ventilator disconnection, and PaO2/FiO2 ratio and SaO2 in PSV Group were superior to the Control Group in the recovery phase. We conclude that the use of PSV in the weaning from mechanical ventilation phase was capable to remain ventilatory and oxygenation parameters appropriate in all evaluations, and weaning only by gradual decrease of RR did not prevent the occurrence of transient hypercapnia at the end of weaning and transient hypoxemia in the recovery from anaesthesia. Considering the healthiness of the animals, these changes were reversed without clinical intervention, but should be considered important recovery events in critical horses.

O desmame é a transição da ventilação mecânica para a espontânea ao final da assistência ventilatória artificial. Não existem estudos específicos sobre esta fase de transição na espécie equina porém, os elevados valores na tensão de dióxido de carbono arterial (PaCO2) ao desmame e os baixos valores na tensão de oxigênio arterial (PaO2) na recuperação pós-anestésica (RPA) refletem a necessidade do estudo de modalidades mais seguras de desmame. Sendo assim, este estudo objetivou comparar dois diferentes protocolos de desmame da ventilação mecânica em equinos hígidos. Para tanto, foram utilizados 20 equinos, de 5±2 anos de idade e pesando 456±90 kg, submetidos a procedimento cirúrgico em decúbito dorsal. Os animais foram divididos aleatoriamente em 2 grupos de acordo com o protocolo de desmame, sendo considerado Grupo Controle os animais que foram submetidos a diminuição gradual da frequência respiratória (FR) isoladamente e Grupo PSV os animais que foram submetidos à redução da FR associada à administração de pressão de suporte ventilatório (PSV). Avaliou-se os parâmetros cardiovasculares, de ventilação, de oxigenação e metabólicos durante o desmame, a desconexão da ventilação mecânica e a RPA. Ao final do desmame, o Vexp (12,49±1,93 L) e o VT (28,10±6,17 mL/kg) do Grupo PSV foram superiores aos do Grupo Controle (Vexp de 7,66±2,66 L e VT de 16,88±4,30 mL/kg). Durante o desmame, a PaCO2 aumentou 29% (de 44±3 mmHg para 57±6 mmHg) e houve diminuição de 28% da relação PaO2/FiO2 (de 391±68 mmHg para 280±28) e de 9% da SaO2 (de 100±1% para 91±3%) apenas no Grupo Controle. Na RPA houve hipoxemia transitória no Grupo Controle após 15 (PaO2 de 48±5 mmHg) e 35 minutos (PaO2 de 57±7 mmHg) da desconexão do ventilador, e no Grupo PSV obteve-ve relação PaO2/FiO2 e SaO2 superior à do Grupo Controle durante a RPA. Concluiu-se que o uso da PSV no desmame foi capaz de manter os parâmetros ventilatórios e de oxigenação adequados durante todos os momentos de avaliação, e o desmame por redução gradativa da FR não impediu a ocorrência de hipercapnia transitória ao final do desmame e hipoxemia transitória na RPA. Considerando-se a higidez dos animais, estas alterações foram revertidas sem intervenção clínica, mas devem ser consideradas em animais debilitados. / Weaning from mechanical ventilation is the transition from mechanical to spontaneous ventilation at the end of the ventilatory support. There are no specific studies about this transition phase in horses. However, high tension of carbon dioxide pressure (PaCO2) at weaning and low values of arterial oxygen tension (PaO2) during recovery from anaesthesia suggest the need to study safer modalities of weaning. The scope of this study was to compare two weaning protocols from mechanical ventilation in healthy horses. With this purpose we studied 20 horses with a mean age of 5±2 years and a mean weight of 456±90 kg, scheduled to surgery in dorsal recumbency. Animals were randomly assigned one of the 2 weaning protocols, considering from Control Group those animals submitted to gradual decrease in respiratory rate (RR) set alone and from PSV Group those animals submitted to gradual decrease in RR associated with pressure support ventilation (PSV) administration. We evaluated cardiovascular, ventilatory, oxygenation and metabolic parameters during weaning, ventilator disconnection and recovery from anaesthesia. At the end of weaning, Vexp (12,49±1,93 L) and VT (28,10±6,17 mL/kg) of PSV Group were superior to the Control Group (Vexp of 7.66±2.66 L and VT of 16.88±4.30 mL/kg). During weaning PaCO2 increased by 29% (44±3 mmHg to 57±6 mmHg) and there was increasing PaO2/FiO2 ratio by 28% (391±68 mmHg to 280±28) and SaO2 by 9% (100±1% to 91±3%) only in Control Group. In the recovery phase there was transient hypoxemia in Control Group after 15 (PaO2 of 48±5 mmHg) and 35 minutes (PaO2 of 57±7 mmHg) of ventilator disconnection, and PaO2/FiO2 ratio and SaO2 in PSV Group were superior to the Control Group in the recovery phase. We conclude that the use of PSV in the weaning from mechanical ventilation phase was capable to remain ventilatory and oxygenation parameters appropriate in all evaluations, and weaning only by gradual decrease of RR did not prevent the occurrence of transient hypercapnia at the end of weaning and transient hypoxemia in the recovery from anaesthesia. Considering the healthiness of the animals, these changes were reversed without clinical intervention, but should be considered important recovery events in critical horses.

Se compararon dos experiencias de inducción anestésica en seis gatos premedicados con acepromacina y buprenorfina: cámara (exp. 1) o mascarilla (exp. 2). En cada experiencia se empleó isofluorano o sevofluorano vehiculados en oxígeno o en una mezcla de oxígeno y óxido nitroso según grupo. Se valoró la calidad de forma subjetiva y la velocidad de inducción en base a distintos tiempos medidos durante esta fase. Tras un mantenimiento de treinta minutos en el que se registraron distintos parámetros cardiorrespiratorios y la temperatura corporal, se evaluó la calidad y velocidad de recuperación anestésica. No se observaron diferencias en cuanto a los tiempos o calidad de inducción o recuperación anestésica entre isofluorano o sevofluorano con o sin óxido nitroso. Los parámetros cardiorrespiratorios durante el mantenimiento fueron similares entre grupos. En conclusión, a pesar de las mejores propiedades del sevofluorano, el isofluorano sigue siendo un anestésico de elecció n para procedimientos de corta duración en gatos.

Hintergrund: In dieser Arbeit wurde untersucht, ob durch die Nutzung von Remifentanil eine Verbesserung der Narkoseführung und Beschleunigung der postoperativen Erholung bei kurzen, schmerzarmen, diagnostischen Eingriffen zu erzielen ist. In der vorliegenden Studie wird ein Narkosekonzept unter Verwendung von Remifentanil/Propofol/Isofluran einer häufig für kurze gynäkologische Operationen genutzten Kombination Ketamin/Propofol/Lachgas gegenübergestellt. Methode: Die Untersuchung fand im Zeitraum April 1997 bis März 1998 im Krankenhaus im Friedrichshain (Berlin) statt. Einer statistischen Zufallsliste entsprechend wurden 108 Patientinnen, die vorher festgelegte Einschlusskriterien erfüllten, einer der beiden Narkosemethoden im einfach-blind Modus zugeordnet. Zur Bearbeitung der Fragestellung wurden kurze gynäkologische Eingriffe (Kürettagen, Interruptiones) ausgewählt. Die Dokumentation der Erholung erfolgte unmittelbar postnarkotisch unter Anwendung psychomotorischer und kognitiver Leistungstests (Memo- Test, Zahlen nachsprechen, Zahlenverbindungstest, Test d2, Maddox wing, Finger-Tapping). Die Aussage dieser Untersuchungen wurde durch Analogskalen (Schmerz-Score, Befindlichkeitsskala) und standardisierte Fragen (intraoperatives Träumen, Zufriedenheit) ergänzt. Die Teilnehmerinnen wurden dreimal hintereinander der selben standardisierten Untersuchungs-, Test- und Befragungsfolge unterzogen. Ergebnisse: Die beiden Untersuchungsgruppen waren hinsichtlich der allgemeinen Ausgangsdaten Alter, Gewicht, Größe, Body-Maß-Index und Nebenerkrankungen vergleichbar. Hinsichtlich der am Vortag (t0) erhobenen Ausgangsdaten und der Verteilung von Persönlichkeitscharakteristika gab es zwischen den Gruppen keine Unterschiede. Die in den Untersuchungen erhobenen Daten zeigten deutliche Vorteile in der psychomotorischen Erholung für die Remifentanil-Gruppe. Schnellere postoperative Erholung konnte durch die psychomotorischen Leistungstests sowie in den Analogskalen belegt werden. Vorteil der Verwendung von Remifentanil ist das Erwachen am Ende der Operation mit sofortigem Wiedererlangen der Koordination. Die narkosebedingten Nachwirkungen Übelkeit und Erbrechen sind selten und die Patienten fühlen sich wohl. Ein entscheidender Nachteil der Kombination Propofol/Remifentanil ist jedoch der intraoperative Abfall von Blutdruck und Herzfrequenz. In der Ketamin-Gruppe ist die Häufigkeit intraoperativer Träume erstaunlich hoch. Schlussfolgerung: Der Einsatz von Remifentanil bei Eingriffen, die postoperativ mit geringen bis mäßigen Schmerzen verbunden sind, sichert eine komplikationsarme und im Vergleich zu Ketamin schnellere postoperative Erholung. Der Überwachungsaufwand und die Überwachungsdauer können somit erheblich reduziert werden. Der indikationsgerechte Einsatz von Remifentanil bei diesen Eingriffen kann dazu beitragen, die Patientensicherheit zu erhöhen und gleichzeitig Aufwand und Kosten für die postoperative Patientenbetreuung zu senken. / Background: Aim of this study was to figure out, if the use of remifentanyl can improve management of anaesthesia and cause faster recovery after minor gynaecological operative procedures. For that reason we compared the common anaesthetic procedure using ketamine/ propofol/ nitrous oxide with the combination remifentanil/ propofol/ isoflurane. Method: The investigation was performed during April 1997 until March 1998 in the hospital Krankenhaus im Friedrichshain (Berlin). 108 female patients, who met fixed inclusion criteria before, were assigned to a statistic coincidence list according to one of the two methods of anaesthesia in single-blind mode. Short gynaecological interventions as curettages or termination of pregnancy were selected for the study. The recovery documentation took place immediately post narcotic, using psychomotor and cognitive performance tests (word recall, number recall, Maddox wing, finger tapping, number-connection test, test d2). The results of these investigations were supplemented by the results of line analogue rating scales (pain score, feeling scale) and standardized questions (intraoperative dreaming, satisfaction). According to a standardized schedule, the participants underwent three times the same standardized investigations-, tests- and questioning sequences. Results: The two groups of investigations were comparable regarding the general data age, weight, size, and Body measure index and side diseases. Regarding the original data, obtained at the previous day (t0), and the distribution of personality characteristics, there were no differences between the groups. The data raised in the investigations showed clear advantages in the psychomotor recovery for the group of remifentanil. Faster post narcotic recovery can be proved by the psychomotor performance tests as well as in the rating scales. Most important advantage of the use of remifentanil is awaking at the end of the operation with the immediate regaining of the coordination. The anaesthesia related side effects as nausea and vomiting are rare and the patients feel well. A remarkable disadvantage of the combination propofol/remifentanil is, however, the intraoperative drop of blood pressure and heart frequency, especially in elderly patients. Frequency of intraoperative dreaming can be observed much more in the ketamine group. Conclusion: By the use of remifentanil in operative procedures, causing less, up to moderate postoperative pain, we secured rare complications and post surgical faster recovery compared with the ketamine group. The postoperative monitoring expenditure as well as the duration of monitoring can be substantially reduced. The indication-fair use of remifentanil in these surgical procedures surgery can contribute to increase patient security and to lower expenditure and costs of the post surgical patient care at the same time.