Assessing the influence of mechanical ventilation on blood gases and blood pressure in rattlesnakes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The effects of 2 levels of the inspired oxygen fraction on blood gas variables in propofol-anesthetized dogs with high intracranial pressure

The influence of 2 different levels of the inspired oxygen fraction (FiO(2)) on blood gas variables was evaluated in dogs with high intracranial pressure (ICP) during propofol anesthesia (induction followed by a continuous rate infusion [CRI] of 0.6 mg/kg/min) and intermittent positive pressure ventilation (IPPV). Eight adult mongrel dogs were anesthetized on 2 occasions, 21 d apart, and received oxygen at an FiO(2) of 1.0 (G100) or 0.6 (G60) in a randomized crossover fashion. A fiberoptic catheter was implanted on the surface of the right cerebral cortex for assessment of the ICP. An increase in the ICP was induced by temporary ligation of the jugular vein 50 min after induction of anesthesia and immediately after baseline measurement of the ICP. Blood gas measurements were taken 20 min later and then at 15-min intervals for 1 h. Numerical data were submitted to Morrison's multivariate statistical methods. The ICP, the cerebral perfusion pressure and the mean arterial pressure did not differ significantly between FiO(2) levels or measurement times after jugular ligation. The only blood gas values that differed significantly (P < 0.05) were the arterial oxygen partial pressure, which was greater with G100 than with G60 throughout the procedure, and the venous haemoglobin saturation, that was greater with G100 than with G60 at M0. There were no significant differences between FiO(2) levels or measurement times in the following blood gas variables: arterial carbon dioxide partial pressure, arterial hemoglobin saturation, base deficit, bicarbonate concentration, pH, venous oxygen partial pressure, venous carbon dioxide partial pressure and the arterial-to-end-tidal carbon dioxide difference.

Comparison between noninvasive mechanical ventilation and standard oxygen therapy in children up to 3 years old with respiratory failure after extubation: a pilot prospective randomized clinical study

Objectives: The effectiveness of noninvasive positive-pressure ventilation in preventing reintubation due to respiratory failure in children remains uncertain. A pilot study was designed to evaluate the frequency of extubation failure, develop a randomization approach, and analyze the feasibility of a powered randomized trial to compare noninvasive positive-pressure ventilation and standard oxygen therapy post extubation for preventing reintubation within 48 hours in children with respiratory failure.Design: Prospective pilot study.Setting: PICU at a university-affiliated hospital.Patients: Children aged between 28 days and 3 years undergoing invasive mechanical ventilation for greater than or equal to 48 hours with respiratory failure after programmed extubation.Interventions: Patients were prospectively enrolled and randomly assigned into noninvasive positive-pressure ventilation group and inhaled oxygen group after programmed extubation from May 2012 to May 2013.Measurements and Main Results: Length of stay in PICU and hospital, oxygenation index, blood gas before and after tracheal extubation, failure and reason for tracheal extubation, complications, mechanical ventilation variables before tracheal extubation, arterial blood gas, and respiratory and heart rates before and 1 hour after tracheal extubation were analyzed. One hundred eight patients were included (noninvasive positive-pressure ventilation group, n = 55 and inhaled oxygen group, n = 53), with 66 exclusions. Groups did not significantly differ for gender, age, disease severity, Pediatric Risk of Mortality at admission, tracheal intubation, and mechanical ventilation indications. There was no statistically significant difference in reintubation rate (noninvasive positive-pressure ventilation group, 9.1%; inhaled oxygen group, 11.3%; p > 0.05) and length of stay (days) in PICU (noninvasive positive-pressure ventilation group, 3 [116]; inhaled oxygen group, 2 [1-25]; p > 0.05) or hospital (noninvasive positive-pressure ventilation group, 19 [7-141]; inhaled oxygen group, 17 [8-80]).Conclusions: The study indicates that a larger randomized trial comparing noninvasive positive-pressure ventilation and standard oxygen therapy in children with respiratory failure is feasible, providing a basis for a future trial in this setting. No differences were seen between groups. The number of excluded patients was high.

Ventilação mecânica não-invasiva no pós-operatório de cirurgia cardíaca: atualização da literatura

Este estudo objetivou atualizar os conhecimentos em relação à utilização da ventilação mecânica não-invasiva (VMNI) no pós-operatório de cirurgia cardíaca e identificar se há indícios da superioridade de uma forma de modalidade de VMNI em relação à outra. Foi realizada revisão da literatura entre 2006 a 2011, a partir das bases de dados PubMed, SciELO e Lilacs, utilizando os descritores respiração artificial, pressão positiva contínua nas vias aéreas, ventilação com pressão positiva intermitente e cirurgia cardíaca, e seus correspondentes na língua inglesa, os quais foram pesquisados em cruzamentos. A partir dos critérios adotados, foram selecionados nove artigos, dos quais seis demonstraram aplicações de VMNI, por meio de modalidades como pressão positiva contínua nas vias aéreas, pressão positiva com dois níveis pressóricos e respiração com pressão positiva intermitente, no pós-operatório de cirurgia cardíaca, e, três realizaram comparações entre as diferentes modalidades. As modalidades de VMNI descritas na literatura foram utilizadas com resultados satisfatórios. Estudos que comparam diferentes modalidades são escassos, contudo alguns demonstraram superioridade de uma modalidade de VMNI, como é o caso da respiração com pressão positiva intermitente na reversão da hipoxemia e da pressão positiva com dois níveis pressóricos na melhora da oxigenação, da frequência respiratória e frequência cardíaca desses pacientes, em comparação a outras modalidades.

The effect of intracuff alkalinized 2% lidocaine on emergence coughing, sore throat, and hoarseness in smokers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of the isoflurane-sparing effects of lidocaine and fentanyl during surgery in dogs

Objective-To evaluate the isoflurane-sparing effects of lidocaine and fentanyl administered by constant rate infusion (CRI) during surgery in dogs.Design-Randomized prospective study.Animals-24 female dogs undergoing unilateral mastectomy because of mammary neoplasia.Procedures-After premedication with acepromazine and morphine and anesthetic induction with ketamine and diazepam, anesthesia in dogs (n = 8/group) was maintained with isoflurane combined with either saline (0.9% NaCl) solution (control), liclocaine (1.5 mg/kg [0.68 mg/lb], IV bolus, followed by 250 mu g/kg/min [113 mu g/lb/min], CRI), or fentanyl (5 mu g/kg [2.27 mu g/lb], IV bolus, followed by 0.5 mu g/kg/min [0.23 mu g/lb/min], CRI). Positive-pressure ventilation was used to maintain eucapnia. An anesthetist unaware of treatment, endtidal isoflurane (ETiso) concentration, and vaporizer concentrations adjusted a nonprecision vaporizer to maintain surgical depth of anesthesia. Cardiopulmonary variables and ETiso values were monitored before and after beginning surgery.Results-Heart rate was lower in the fentanyl group. Mean arterial pressure did not differ among groups after surgery commenced. In the control group, mean +/- SD ETiso values ranged from 1.16 +/- 0.35% to 1.94 +/- 0.96%. Fentanyl significantly reduced isoflurane requirements during surgical stimulation by 54% to 66%, whereas the reduction in ETiso concentration (34% to 44%) observed in the lidocaine group was not significant.Conclusions and Clinical Relevance-Administration of fentanyl resulted in greater isoflurane sparing effect than did liclocaine. However, it appeared that the low heart rate induced by fentanyl may partially offset the improvement in mean arterial pressure that would be expected with reduced isoflurane requirements.

Comparação entre a ventilação com pressão positiva intermitente ou pressão controlada em equinos anestesiados com isofluorano

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of continuous rate infusion of butorphanol in isoflurane-anesthetized calves

PURPOSE:To assess the hemodynamic changes and bispectral index (BIS) following administration of a continuous rate infusion (CRI) of butorphanol in isoflurane-anesthetized calves.METHODS: Eight calves weighing 110 ± 12 kg were included in the study. Anesthesia was induced with 5% isoflurane in O2 delivered via face mask and maintained with end-tidal concentration of 1.4%. IPPV was set to a peak inspiratory airway pressure of 15 cmH2O and respiratory rate of six breaths minute-1. Forty minutes after the start of anesthetic maintenance, 0.1 mg kg-1butorphanol was administered intravenously, followed by a CRI of 20 µg kg-1 minute-1. Hemodynamic variables and BIS were recorded before butorphanol administration (T0), and at 10, 20, 40 and 80 minutes following the CRI. Anesthesia was discontinued after the last recording and the calves were allowed to recover. The time to sternal recumbency (SRE) and standing (ST) were evaluated.RESULTS: There were no significant differences between the moments in all hemodynamic variables and BIS. The time to SRE and ST was 9 ± 5 and 14 ± 7 minutes, respectively.CONCLUSION: The continuous rate infusion did not produce clinically relevant changes in hemodynamic or bispectral index values compared to baseline in mechanically ventilated and unstimulated calves anesthetized at 1.4% isoflurane.

Bispectral index in calves anesthetized with xylazine, midazolam, ketamine, isoflurane and subjected to continuous rate infusion of lidocaine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A lung computed tomographic assessment of positive end-expiratory pressure-induced lung overdistension

The aim of this study was to assess positive end-expiratory pressure (PEEP)-induced lung overdistension and alveolar recruitment in six patients with acute lung injury (ALI) using a computed tomographic (CT) scan method. Lung overdistension was first determined in six healthy volunteers in whom CT sections were obtained at FRC and at TLC with a positive airway pressure of 30 cm H2O. In patients, lung volumes were quantified by the analysis of the frequency distribution of CT numbers on the entire lung at zero end-expiratory pressure (ZEEP) and PEEP. In healthy volunteers at FRC, the distribution of the density histograms was monophasic with a peak at -791 ± 12 Hounsfield units (HU). The lowest CT number observed was -912 HU. At TLC, lung volume increased by 79 ± 35% and the peak CT number decreased to -886 ± 26 HU. More than 70% of the increase in lung volume was located below -900 HU, suggesting that this value can be considered as the threshold separating normal aeration from overdistension. In patients with ALI, at ZEEP the distribution of density histograms was either monophasic (n = 3) or biphasic (n = 3). The mean CT number was -319 ± 34 HU. At PEEP 13 ± 3 cm H2O, lung volume increased by 47 ± 19% whereas mean CT number decreased to -538 ± 171 HU. PEEP induced a mean alveolar recruitment of 320 ± 160 ml and a mean lung overdistension of 238 ± 320 ml. In conclusion, overdistended lung parenchyma of healthy volunteers is characterized by a CT number below -900 HU. This threshold can be used in patients with ALI for differentiating PEEP-induced alveolar recruitment from lung overdistension.

Ammonia emissions in tunnel-ventilated broiler houses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Simulação em protótipo do sistema respiratório com ventilador de pressão positiva e análise das alterações devido às obstruções do fluxo aéreo pulmonar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos da Ventilação Mecânica não Invasiva sobre a Modulação Autonômica Cardíaca

This review is intended to gather together recent studies that explore the effects of different types of noninvasive ventilation (NIV) on the autonomic nervous system, assessed through heart rate variability (HRV). A search for papers was conducted in the PubMed, PEDro, SciELO and Lilacs databases with the following descriptors: noninvasive ventilation, CPAP ventilation, intermittent positive pressure breathing and autonomic nervous system, for the period between 2008 and 2012. After eliminating papers not addressing the topic, we selected six studies, of which five applied NIV in CPAP mode and one used biphasic positive airway pressure. In general, the findings suggest that NIV promotes changes in autonomic modulation that are dependent on the conditions of the subjects analyzed and the time when these rates are assessed, meaning acute or long-term effects.

Efeitos hemodinâmicos da ventilação monopulmonar em cães anestesiados com isofluorano ou infusão contínua de propofol

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Edema agudo pulmonar associado à obstrução das vias aéreas. Relato de caso

BAKGROUND AND OBJECTIVES: Negative pressure pulmonary edema has been defined as non-cardiogenic edema, with transudation of fluid to the interstitial space of the lungs due to an increase in negative intrathoracic pressure secondary to obstruction of the upper airways. This is the case of a healthy patient who underwent general anesthesia and developed acute pulmonary edema after extubation. CASE REPORT: A 23-year old female patient, physical status ASA II, underwent gynecologic videolaparoscopy under general anesthesia. The procedure lasted 3 hours without intercurrence. After extubation the patient developed laryngeal spasm and reduction in oxygen saturation. The patient improved after placement of an oral cannula and administration of oxygen under positive pressure with a face mask. Once the patient was stable she was transferred to the recovery room where, shortly after her arrival, she developed acute pulmonary edema with elimination of bloody serous secretion. Treatment consisted of elevation of the head, administration of oxygen via a face mask, furosemide and fluid restriction. Chest X-ray was compatible with acute pulmonary edema and normal cardiac area. Electrocardiogram (ECG), echocardiogram and cardiac enzymes were normal. The condition of the patient improved and she was discharged from the hospital the following day, asymptomatic. CONCLUSIONS: Acute pulmonary edema associated with obstruction of the upper airways can aggravate surgical procedures with low morbidity, affecting mainly young patients. Early treatment should be instituted because it has a fast evolution and, in most cases, resolves without lasting damages. © Sociedade Brasileira de Anestesiologia, 2008.