Intraoperative pulmonary hyperdistention estimated by transthoracic lung ultrasound: A pilot study.

INTRODUCTION: Transthoracic lung ultrasound can assess atelectasis reversal and is considered as unable to detect associated hyperdistention. In this study, we describe an ultrasound pattern highly suggestive of pulmonary hyperdistention. METHODS: Eighteen patients with normal lungs undergoing lower abdominal surgery were studied. Electrical impedance tomography was calibrated, followed by anaesthetic induction, intubation and mechanical ventilation. To reverse posterior atelectasis, a recruitment manoeuvre was performed. Positive-end expiratory pressure (PEEP) titration was then obtained during a descending trial - 20, 18, 16, 14, 12, 10, 8, 6 and 4cmH2O. Ultrasound and electrical impedance tomography data were collected at each PEEP level and interpreted by two independent observers. Spearman correlation test and receiving operating characteristic curve were used to compare lung ultrasound and electrical impedance tomography data. RESULTS: The number of horizontal A lines increased linearly with PEEP: from 3 (0, 5) at PEEP 4cmH2O to 10 (8, 13) at PEEP 20cmH2O. The increase number of A lines was associated with a parallel and significant decrease in intercostal space thickness (p=0.001). The lung ultrasound threshold for detecting pulmonary hyperdistention was defined as the number of A lines counted at the PEEP preceding the PEEP providing the best respiratory compliance. Six A lines was the median threshold for detecting pulmonary hyperdistention. The area under the receiving operating characteristic curve was 0.947. CONCLUSIONS: Intraoperative transthoracic lung ultrasound can detect lung hyperdistention during a PEEP descending trial. Six or more A lines detected in normally aerated regions can be considered as indicating lung hyperdistention. TRIAL REGISTRATION: NCT02314845 Registered on ClinicalTrials.gov.

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study.

OBJECTIVE: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. METHODS: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. RESULTS: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. CONCLUSIONS: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study / Desempenho de ventiladores de UTI durante ventilação não invasiva com grandes vazamentos em máscara facial total: estudo em simulador mecânico

Objective: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. Methods: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Results: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. Conclusions: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM. .

Objetivo: O desconforto e a falta de adaptação às interfaces de ventilação não invasiva (VNI) são obstáculos ao sucesso da VNI. A máscara facial total (MFT) é uma interface de VNI considerada muito confortável. No entanto, devido a seu grande volume interno e, consequentemente, ao aumento da reinalação de CO2, a MFT tem orifícios que permitem vazamentos proximais para melhorar a eliminação de CO2. É possível que os ventiladores usados na UTI não compensem esse vazamento adequadamente. Neste estudo, buscamos determinar se ventiladores de UTI com módulo de VNI podem ser usados com MFT com grandes vazamentos. Métodos: Estudo em simulador mecânico conduzido em um laboratório universitário de pesquisa. Oito ventiladores de UTI equipados para realizar VNI e um ventilador específico para VNI foram conectados a uma MFT com grandes vazamentos. Todos foram testados com dois níveis de positive end-expiratory pressure (PEEP, pressão expiratória final positiva) e três níveis de pressão de suporte. As variáveis analisadas foram disparo do ventilador, ciclagem, vazamento total e pressurização. Resultados: Dos oito ventiladores de UTI, quatro não funcionaram (autodisparo ou desligamento inapropriado por detecção incorreta de desconexão), três funcionaram com alguns problemas (valores baixos de PEEP ou grande atraso na ciclagem do ventilador) e apenas um funcionou adequadamente. Conclusões: A maioria dos ventiladores de UTI testados mostrou-se inadequada para VNI com MFT com grandes vazamentos. .

Evaluation of manual resuscitators used in ICUs in Brazil.

OBJECTIVE: To evaluate the performance of manual resuscitators (MRs) used in Brazil in accordance with international standards. METHODS: Using a respiratory system simulator, four volunteer physiotherapists employed eight MRs (five produced in Brazil and three produced abroad), which were tested for inspiratory and expiratory resistance of the patient valve; functioning of the pressure-limiting valve; and tidal volume (VT) generated when the one-handed and two-handed techniques were used. The tests were performed and analyzed in accordance with the American Society for Testing and Materials (ASTM) F920-93 criteria. RESULTS: Expiratory resistance was greater than 6 cmH2O . L-1 . s-1 in only one MR. The pressure-limiting valve, a feature of five of the MRs, opened at low pressures (< 17 cmH2O), and the maximal pressure was 32.0-55.9 cmH2O. Mean VT varied greatly among the MRs tested. The mean VT values generated with the one-handed technique were lower than the 600 mL recommended by the ASTM. In the situations studied, mean VT was generally lower from the Brazilian-made MRs that had a pressure-limiting valve. CONCLUSIONS: The resistances imposed by the patient valve met the ASTM criteria in all but one of the MRs tested. The pressure-limiting valves of the Brazilian-made MRs usually opened at low pressures, providing lower VT values in the situations studied, especially when the one-handed technique was used, suggesting that both hands should be used and that the pressure-limiting valve should be closed whenever possible.

Evaluation of manual resuscitators used in ICUs in Brazil / Avaliação de reanimadores manuais utilizados em UTIs brasileiras

OBJECTIVE: To evaluate the performance of manual resuscitators (MRs) used in Brazil in accordance with international standards. METHODS: Using a respiratory system simulator, four volunteer physiotherapists employed eight MRs (five produced in Brazil and three produced abroad), which were tested for inspiratory and expiratory resistance of the patient valve; functioning of the pressure-limiting valve; and tidal volume (VT) generated when the one-handed and two-handed techniques were used. The tests were performed and analyzed in accordance with the American Society for Testing and Materials (ASTM) F920-93 criteria. RESULTS: Expiratory resistance was greater than 6 cmH2O . L−1 . s−1 in only one MR. The pressure-limiting valve, a feature of five of the MRs, opened at low pressures (< 17 cmH2O), and the maximal pressure was 32.0-55.9 cmH2O. Mean VT varied greatly among the MRs tested. The mean VT values generated with the one-handed technique were lower than the 600 mL recommended by the ASTM. In the situations studied, mean VT was generally lower from the Brazilian-made MRs that had a pressure-limiting valve. CONCLUSIONS: The resistances imposed by the patient valve met the ASTM criteria in all but one of the MRs tested. The pressure-limiting valves of the Brazilian-made MRs usually opened at low pressures, providing lower VT values in the situations studied, especially when the one-handed technique was used, suggesting that both hands should be used and that the pressure-limiting valve should be closed whenever possible. .

OBJETIVO: Avaliar o desempenho de reanimadores manuais (RMs) utilizados no Brasil conforme critérios definidos por uma norma internacional. MÉTODOS: Utilizando um simulador do sistema respiratório, oito RMs manuais (cinco produzidos no Brasil e três importados) foram avaliados em relação a resistência inspiratória e expiratória da válvula para o paciente; funcionamento da válvula limitadora de pressão; e volume corrente (VT) gerado por quatro fisioterapeutas voluntários, utilizando uma ou duas mãos. Para a realização e análise dos testes, foram utilizados critérios sugeridos pela norma da American Society for Testing and Materials (ASTM) F920-93. RESULTADOS: A resistência expiratória foi superior a 6 cmH2O . L−1 . s−1 em apenas um dos RMs testados. A válvula limitadora de pressão, presente em cinco RMs, abriu em baixas pressões (< 17 cmH2O), e a pressão máxima variou de 32,0-55,9 cmH2O. Houve grande variação da média de VT obtido pelos diferentes RMs. Os valores médios de VT utilizando uma mão foram inferiores ao sugerido pela ASTM (600 mL). O VT médio, nas situações estudadas, foi geralmente menor nos RMs nacionais com válvula limitadora de pressão. CONCLUSÕES: As resistências impostas pela válvula do paciente estão de acordo com os critérios da ASTM, com exceção de um RM. As válvulas limitadoras de pressão dos RMs nacionais geralmente abrem em baixas pressões, determinando o fornecimento de um menor VT nas situações estudadas, principalmente com o uso de uma mão, o que sugere que a ventilação deva ser feita com as duas mãos e a válvula limitadora de pressão deva ser fechada sempre que possível. .

Experimental study on the efficiency and safety of the manual hyperinflation maneuver as a secretion clearance technique.

OBJECTIVE: To evaluate, in a lung model simulating a mechanically ventilated patient, the efficiency and safety of the manual hyperinflation (MH) maneuver as a means of removing pulmonary secretions. METHODS: Eight respiratory therapists (RTs) were asked to use a self-inflating manual resuscitator on a lung model to perform MH as if to remove secretions, under two conditions: as routinely applied during their clinical practice; and after receiving verbal instructions based on expert recommendations. In both conditions, three clinical scenarios were simulated: normal lung function, restrictive lung disease, and obstructive lung disease. RESULTS: Before instruction, it was common for an RT to compress the resuscitator bag two times, in rapid succession. Proximal pressure (Pprox) was higher before instruction than after. However, alveolar pressure (Palv) never exceeded 42.5 cmH2O (median, 16.1; interquartile range [IQR], 11.7-24.5), despite Pprox values as high as 96.6 cmH2O (median, 36.7; IQR, 22.9-49.4). The tidal volume (VT) generated was relatively low (median, 640 mL; IQR, 505-735), and peak inspiratory flow (PIF) often exceeded peak expiratory flow (PEF), the median values being 1.37 L/s (IQR, 0.99-1.90) and 1.01 L/s (IQR, 0.55-1.28), respectively. A PIF/PEF ratio < 0.9 (which theoretically favors mucus migration toward the central airways) was achieved in only 16.7% of the maneuvers. CONCLUSIONS: Under the conditions tested, MH produced safe Palv levels despite high Pprox. However, the MH maneuver was often performed in a way that did not favor secretion removal (PIF exceeding PEF), even after instruction. The unfavorable PIF/ PEF ratio was attributable to overly rapid inflations and low VT.

Estudo experimental sobre a eficiência e segurança da manobra de hiperinsuflação manual como técnica de remoção de secreção / Experimental study on the efficiency and safety of the manual hyperinflation maneuver as a secretion clearance technique

OBJETIVO: Avaliar, em um modelo pulmonar simulando um paciente sob ventilação mecânica, a eficiência e a segurança da manobra de hiperinsuflação manual (HM) com o intuito de remover secreção pulmonar. MÉTODOS: Oito fisioterapeutas utilizaram um ressuscitador manual autoinflável para realizar HM com o objetivo de remover secreções, em duas condições: conforme rotineiramente aplicada durante sua prática clínica, e após receberem instruções verbais baseadas em recomendações de especialistas. Três cenários clínicos foram simulados: função pulmonar normal, doença pulmonar restritiva e doença pulmonar obstrutiva. RESULTADOS: Antes da instrução, o uso de duas compressões sequenciais do ressuscitador era comum, e a pressão proximal (Pprox) foi mais alta em relação à obtida após a instrução. Entretanto, a pressão alveolar (Palv) nunca excedeu 42,5 cmH2O (mediana, 16,1; intervalo interquartil [IQ], 11,7-24,5), mesmo com valores de Pprox de até 96,6 cmH2O (mediana, 36,7; IQ, 22,9-49,4). O volume corrente (VC) gerado foi relativamente pequeno (mediana, 640 mL; IQ, 505-735) e o pico de fluxo inspiratório (PFI) geralmente excedeu o pico de fluxo expiratório (PFE): 1,37 L/s (IQ, 0,99-1,90) e 1,01 L/s (IQ, 0,55-1,28), respectivamente. Uma relação PFI/PFE < 0,9 (que teoricamente favorece a migração do muco em direção às vias aéreas centrais) foi obtida em somente 16,7% das manobras. CONCLUSÕES: Nas condições testadas, a HM gerou valores seguros de Palv mesmo com altas Pprox. Entretanto, a HM foi comumente realizada de um modo que não favorecia a remoção de secreção (PFI excedendo PFE) mesmo após a instrução. A relação PFI/PFE desfavorável foi explicada pelas insuflações rápidas e o baixo VC.

OBJECTIVE: To evaluate, in a lung model simulating a mechanically ventilated patient, the efficiency and safety of the manual hyperinflation (MH) maneuver as a means of removing pulmonary secretions. METHODS: Eight respiratory therapists (RTs) were asked to use a self-inflating manual resuscitator on a lung model to perform MH as if to remove secretions, under two conditions: as routinely applied during their clinical practice; and after receiving verbal instructions based on expert recommendations. In both conditions, three clinical scenarios were simulated: normal lung function, restrictive lung disease, and obstructive lung disease. RESULTS: Before instruction, it was common for an RT to compress the resuscitator bag two times, in rapid succession. Proximal pressure (Pprox) was higher before instruction than after. However, alveolar pressure (Palv) never exceeded 42.5 cmH2O (median, 16.1; interquartile range [IQR], 11.7-24.5), despite Pprox values as high as 96.6 cmH2O (median, 36.7; IQR, 22.9-49.4). The tidal volume (VT) generated was relatively low (median, 640 mL; IQR, 505-735), and peak inspiratory flow (PIF) often exceeded peak expiratory flow (PEF), the median values being 1.37 L/s (IQR, 0.99-1.90) and 1.01 L/s (IQR, 0.55-1.28), respectively. A PIF/PEF ratio < 0.9 (which theoretically favors mucus migration toward the central airways) was achieved in only 16.7% of the maneuvers. CONCLUSIONS: Under the conditions tested, MH produced safe Palv levels despite high Pprox. However, the MH maneuver was often performed in a way that did not favor secretion removal (PIF exceeding PEF), even after instruction. The unfavorable PIF/ PEF ratio was attributable to overly rapid inflations and low V T.

Evaluation of resistance in 8 different heat-and-moisture exchangers: effects of saturation and flow rate/profile.

INTRODUCTION: When endotracheal intubation is required during ventilatory support, the physiologic mechanisms of heating and humidifying the inspired air related to the upper airways are bypassed. The task of conditioning the air can be partially accomplished by heat-and-moisture exchangers (HMEs). OBJECTIVES: To evaluate and compare with respect to imposed resistance, different types/models of HME: (1) dry versus saturated, (2) changing inspiratory flow rates. MATERIALS AND METHODS: Eight different HMEs were studied using a lung model system. The study was conducted initially by simulating spontaneous breathing, followed by connecting the system directly to a mechanical ventilator to provide pressure-support ventilation. RESULTS: None of the encountered values of resistance (0.5\N3.6 cm H(2)O/L/s) exceeded the limits stipulated by the previously described international standard for HMEs (International Standards Organization Draft International Standard 9360-2) (not to exceed 5.0 cm H(2)O with a flow of 1.0 L/s, even when saturated). The hygroscopic HME had less resistance than other types, independent of the precondition status (dry or saturated) or the respiratory mode. The hygroscopic HME also had a lesser increase in resistance when saturated. The resistance of the HME was little affected by increases in flow, but saturation did increase resistance in the hydrophobic and hygroscopic/hydrophobic HME to levels that could be important at some clinical conditions. CONCLUSIONS: Resistance was little affected by saturation in hygroscopic models, when compared to the hydrophobic or hygroscopic/hydrophobic HME. Changes in inspiratory flow did not cause relevant alterations in resistance.

Comparaçäo entre mulheres e homens alcoolistas em relaçäo a dados sociodemográficos e outras características relacionadas ao uso de álcool / Comparison between alcoholic men and women in relation to socio-demographic data and to other alcohol use-related characteristics

Os autores discutem as diferenças existentes entre mulheres alcoolistas (n=68) e homens alcoolistas (n=68), todos pacientes de um hospital público universitário. Foram pesquisados fatores demográficos e outras características ligadas ao uso do álcool. Verificou-se que os grupos em questäo diferem significativamente quanto à idade de aumento de ingestäo e quanto ao número de tentativas de suicídio, sendo semelhantes quanto às características estudadas. Os autores supöem que uma amostra maior possa confirmar estatísticamente outros dados e apontam a importância dessa linha de pesquisa, dado o aumento da populaçäo alcoolista feminina

Comparacao entre mulheres e homens alcoolistas em relacao a dados sociodemograficos e outras caracteristicas relacionadas ao uso de alcool

Os autores discutem as diferencas existentes entre mulheres alcoolistas (n=68) e homens alcooliistas (n=68), todos pacientes de um hospital publico universitario. Foram pesquisados fatores demograficos e outras caracteristicas ligadas ao uso do alcool. Verificou-se que os grupos em questao diferem significativamente quanto a idade de aumento de ingestao e quanto ao numero de tentativas de suicidio, sendo semelhantes quanto as outras caracteristicas estudadas. Os autores supoem que uma amostra maior possa confirmar estatisticamente outros dados e apontam a importancia dessa linha de pesquisa, dado o aumento da populacao alcoolista feminina.