Respiratory mechanics and morphometric changes during anesthesia with ketamine in normal rats

Ketamine is believed to reduce airway and pulmonary tissue resistance. The aim of the present study was to determine the effects of ketamine on the resistive, elastic and viscoelastic/inhomogeneous mechanical properties of the respiratory system, lungs and chest wall, and to relate the mechanical data to findings from histological lung analysis in normal animals. Fifteen adult male Wistar rats were assigned randomly to two groups: control (N = 7) and ketamine (N = 8). All animals were sedated (diazepam, 5 mg, ip) and anesthetized with pentobarbital sodium (20 mg/kg, ip) or ketamine (30 mg/kg, ip). The rats were paralyzed and ventilated mechanically. Ketamine increased lung viscoelastic/inhomogeneous pressure (26 percent) compared to the control group. Dynamic and static elastances were similar in both groups, but the difference was greater in the ketamine than in the control group. Lung morphometry demonstrated dilation of alveolar ducts and increased areas of alveolar collapse in the ketamine group. In conclusion, ketamine did not act at the airway level but acted at the lung periphery increasing mechanical inhomogeneities possibly resulting from dilation of distal airways and alveolar collapse

Inspiratory flow-volume curve in snoring patients with and without obstructive sleep apnea

We analyzed the flow-volume curves of 50 patients with complaints of snoring and daytime sleepiness in treatment at the Pneumology Unit of the University Hospital of Brasília. The total group was divided into snorers without obstructive sleep apnea (OSA) (N = 19) and snorers with OSA (N = 31); the patients with OSA were subdivided into two groups according to the apnea/hypopnea index (AHI): AHI<20/h (N = 14) and AHI>20/h (N = 17). The control group (N = 10) consisted of nonsmoking subjects without complaints of snoring, daytime sleepiness or pulmonary diseases. The population studied (control and patients) consisted of males of similar age, height and body mass index (BMI); spirometric data were also similar in the four groups. There was no significative difference in the ratio of forced expiratory and inspiratory flows (FEF50 per cent/FIF50 per cent) in any group: control, 0.89; snorers, 1.11; snorers with OSA (AHI<20/h), 1.42, and snorers with OSA (AHI>20/h), 1.64. The FIF at 50 per cent of vital capacity (FIF50 per cent) of snoring patients with or without OSA was lower than the FIF50 per cent of the control group (P<0.05): snorers 4.30 l/s; snorers with OSA (AHI>20/h) 3.69 l/s; snorers with OSA (AHI>20/h) 3.17 l/s and control group 5.48 l/s. The FIF50 per cent of patients with severe OSA (AHI>20/h) was lower than the FIF50 per cent of snorers without OSA (P<0.05): 3.17 l/s and 4.30 l/s, respectively. We conclude that 1) the FEF50 per cent/FIF50 per cent ratio is not useful for predicting OSA, and 2) FIF50 per cent is decreased in snoring patients with and without OSA, suggesting that these patients have increased upper airway resistance (UAR).

Sobre um caso se síndrome da apnéia obstrutiva de sono simulando narcolepsia / A case of obstructive sleep apnea syndrome simulating narcolepsy

Descreve-se o caso de um paciente com síndrome da apnéia do sono obstrutiva (SASO), o qual apresentava também queixas sugestivas de narcolepsia. A propedêutica polissonográfica revelou a gravidade do quadro apnéico e o teste das múltiplas latências de adormecimento (TMLA) mostrou REM precoce em duas das cinco oportunidades. A polissonografia com CPAP nasal observou melhora dosono noturno e revelou, no TMLA realizado no dia seguinte, as características narcolépticas.

Avaliaçäo da resposta ao broncodilatador em DPOC e asma / Bronchodilator response in asthma and obstructive bronchopulmonary disease

O presente trabalho constitui análise retrospectiva de 106 espirogramas, que estudou o comportamento de dois grupos de 53 pacientes cada, a saber, DPOC e asma brônquica (AB) diante do uso de broncodilatador (BCD) (fenotenol, 2 bombadas = 200 microgramas). Os resultados obtidos mostraram resposta significativa entre asmáticos (t < 0.05) em comparaçäo com a resposta discreta, mas existente, em pacientes com DPOC. O trabalho aponta como indicadores mais confiáveis para estimar a resposta ao broncodilatador, índice de Tifneau (p=0.43-DPOC e p=0.01-asma), o FEF 25/75 por cento p=0.78-DPOC e p=0.01-asma) e o VEF1 (p=0.37-DPOC e p=0.006-asma), sendo este o mais sensível entre os valores aferidos. Os resultados säo compatíveis com a literatura. Dos 53 casos de asma, 48 säo de ambulatório, 4 da enfermaria e um do Pronto Socorro. Quanto à distribuiçäo por sexo, observou-se prevalência, no DPOC, do sexo masculino da ordem de 41 em 53 casos, enquanto no grupo asma observou-se a prevalência feminina da ordem de 32 em 53 casos (Figura 1). O trabalho é útil para distinçäo simples entre DPOC e ASMA e confirma a expectativa de que a broncorresponsividade constitui atributo singular da asma, prevalente ao nível de grandes vias e com percentual médio de diferença (pré e pós uso de B.C.D.) em torno de 11 por cento

Resistencia vascular e volume pulmonar no pulmao isolado do cao. / Pulmonary volume and vascular resistance in isolated dog lung

A resistencia vascular pulmonar como funcao do fluxo sanguineo foi estudada no lobo isolado do pulmao do cao em diferentes volumes pulmonares. A pressao venosa foi mantida constante e o lobo perfundido com sangue autologo. Os resultados indicam que: a) resistencia vascular pulmonar diminui quando o fluxo sanguineo aumenta; b) a resistencia vascular pulmonar diminui inicialmente, entre o colapso pulmonar total e o volume moderado e aumenta marcadamente entre o volume moderado e a inflacao completa. Os autores sugerem que os dados morfometricos de Weibel poderiam explicar a queda da resistencia vascular na fase inicial de inflacao pulmonar. Durante essa fase as dobras dos capilares septais referidas por Weibel tendem a desaparecer, diminuir a resistencia vascular pulmonar

Avaliacao comparativa do desempenho do espirometro de fole Med-Graf 200. / Comparative evaluation of the foil spirometer Med-Graf 200

Sao realizados testes de avaliacao de desempenho para um espirometro de fole de fabricacao nacional (Med-Graf 200) em comparacao a um espirometro de fole de fabriparacao a um espirometro de campanula Collins 718-B. Os testes compreendem a analise de parametros de respiracao multipla e de respiracao unica, envolvendo testes com voluntarios sadios na faixa de 20 a 39 anos, de ambos os sexos. O equipamento apresenta boas caracteristicas de desempenho e simplicidade de operacao, mas sao observados nos testes comparativos valores ligeiramente superestimados nos parametros de respiracao unica. Diferencas menos significativas sao verificadas tambem nos registros obtidos em testes simulados de respiracao multipla a pequenos volume-minuto. O aparelho de teste e considerado satisfatorio para uso clinico na deteccao e acompanhamento de disfuncoes pulmonares de carater geral

Maximal expiratory flow-volume curve in chronic chagasic patients with megaesophagus with or without megacolon

The maximal expiratory flow-volume curve was used to evaluate existing physiological abnormalities in forty patientes with chronic Chagas'Disease. All patients had megaoesophagus with or without megacolon, some had ECG evidence of cardiomyopathy but none had clinic signs of cardiac failure. The 40 patients were studied in four groups: I)The total group with or without cardiomyopathy. II) 24 patients with associated cardiomyopathy. III) 16 patients without cardiomyopathy. IV) 17 non smoking patients with or without cardiomyopathy. The results indicated that there was: a) a dmininution of the forced vital capacity (FVC) in group I, II and IV; b) a diminution of maximal expiratory flow (Vmax) in group I and II; c) a diminution of the maximal expiratory flow rates at 50% and 25% of the expired vital capacity (Vmax50 and Vmax25) in all four groups. The alterations of the first-second forced expired volume (FEV1) were not significant in any group. Diminution of FVC and Vmax seen to be dependent upon the presence of associated cardiomyopathy while diminution of the Vmax50 and Vmax25 was a constant finding, independent of the presence of cardiopathy