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Hypotension is a common finding in hospitalized, critically ill neonatal foals. Hypotension may be a function of low cardiac output or increased cardiac output and decreased systemic vascular resistance. In the first instance, treatment would include fluids and/or inotropes and in the second, fluids and/or vasopressors. Therefore, cardiac output measurements are expected to help guide the treatment of hypotension associated with critical illness and/or anesthesia in neonatal foals. However, a practical and safe method of measuring cardiac output has not been described for the foal. Lithium dilution, a new method of cardiac output determination not requiring cardiac catheterization, has recently been reported in adult horses. We compared this method to thermodilution in isoflurane anesthetized, 30 to 42 hour old foals and found good agreement (mean bias 0.0474L/min; limits of agreement -3.03 to 3.12) between the two methods in a range of cardiac outputs from 5.4 to 20.4 liters/min. The lithium dilution technique is a practical and reliable method of measuring cardiac output in anesthetized neonatal foals, and warrants investigation in critically ill conscious foals. / Master of Science

Advances in technology have now made it possible to analyze cardiac output (Q) with only a single-breath, making measurements during exercise quicker and less invasive for the subject. Certain non-invasive techniques allow for measurement of the disappearance of a soluble inert gas as it diffuses across the blood-gas barrier in the lungs. The rate of disappearance of the gas is directly proportional to the flow of blood past the lungs and subsequently provides an estimate of pulmonary capillary blood flow (Qc), or Q. The SensorMedics® Corporation (Yorba Linda, CA) has developed a single-breath acetylene (C₂H₂) technique (SensorMedics Vmax 229TM), which includes a simple device to linearize expiratory flow rate by increasing the time by which the sensors can measure the disappearance of the marker gas and improve quantification. The purpose of this investigation was to determine the reproducibility of the C₂H₂ single-breath technique during ramping exercise testing with the addition of a starling resistor in 11 apparently healthy, sedentary volunteers (7 male and 4 female). Subjects performed three maximal ramping exercise test sessions over a 6-week period and Qc was measured at rest and at three time points during the exercise test. The C₂H₂ single-breath Qc measurement technique was shown to be repeatable when systematically related to VO₂ (Qc/VO₂ relation highly correlated r² = 0.72-.74), but slightly lower than previously reported. Means and 95% confidence intervals revealed the precision of the technique over repeated testing days. This method was able to capture Qc measurements at intensities greater than 75% VO₂pk in all subjects with the use of the Starling resistor. Bland-Altman plots reveal Qc measures to be about 50% more variable than highly reproducible measures such as VO₂ and HR. Intraclass reliability coefficients (r) found through repeated measures ANOVA were found to perform low (rx,x= -0.11-0.31) from rest throughout all intensities of exercise. This device is limited in the ability of the sensors to accurately analyze Qc with subjects who are unfamiliar and have difficulty with the single-breath maneuver. Such instances make it difficult for objective, accurate determinations to be made by the clinician. The C₂H₂ single-breath method was found to capture Qc at higher intensities and a high level of precision with the addition of the starling resistor. However, more evidence needs to be analyzed before use of this device can be put into clinical practice. / Master of Science

The effective of additional muscle mass in a priming exercise on cardiac output (Q) and pulmonary oxygen uptake (VO2) kinetics (mean response time, s) were determined in cyclists. Outcomes were measured over four trials, each consisting of a 6-minute legs alone (UAL) or arms and legs (ULO) warm-up, 3 minute passive recovery, then 6 minutes leg cycling (PAL, PLO; respectively). Q was significantly higher preceding exercise onset with PAL compared to PLO or ULO (0.72 ± 0.13 vs. 0.58 ± 0.09, 0.43 ± 0.09 L∙min-1; respectively, P < 0.05). Q kinetics did not differ between unprimed (ULO: 38.9 ± 8.6) and primed exercise regardless of muscle mass (PLO: 38.6 ± 11.0; PAL: 40.7 ± 11.3). VO2 kinetics were faster (P < 0.05) with PAL (36.9 ± 6.0) compared to ULO (58.7 ± 10.5). Muscle mass employed during priming exercise had only slight effect on subsequent VO2 and Q responses.

The effective of additional muscle mass in a priming exercise on cardiac output (Q) and pulmonary oxygen uptake (VO2) kinetics (mean response time, s) were determined in cyclists. Outcomes were measured over four trials, each consisting of a 6-minute legs alone (UAL) or arms and legs (ULO) warm-up, 3 minute passive recovery, then 6 minutes leg cycling (PAL, PLO; respectively). Q was significantly higher preceding exercise onset with PAL compared to PLO or ULO (0.72 ± 0.13 vs. 0.58 ± 0.09, 0.43 ± 0.09 L∙min-1; respectively, P < 0.05). Q kinetics did not differ between unprimed (ULO: 38.9 ± 8.6) and primed exercise regardless of muscle mass (PLO: 38.6 ± 11.0; PAL: 40.7 ± 11.3). VO2 kinetics were faster (P < 0.05) with PAL (36.9 ± 6.0) compared to ULO (58.7 ± 10.5). Muscle mass employed during priming exercise had only slight effect on subsequent VO2 and Q responses.

名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成5年1月28日 平山正昭氏の博士論文として提出された

This thesis provides a first description and proof-of-concept of iterative cardiac output measurement (ICO) – a respiratory, carbon-dioxide (CO2) based method of measuring cardiac output (CO). The ICO method continuously tests and refines an estimate of the CO by attempting to maintain the end-tidal CO2 constant. To validate the new method, ICO and bolus thermodilution CO (TDCO) were simultaneously measured in a porcine model of liver transplant. Linear regression analysis revealed the equation ICO = 0.69•TDCO + 0.65 with a Pearson correlation coefficient of 0.89. Analysis by the method of Bland and Altman showed a bias of -0.2 L/min with 95% limits of agreement from -1.1 to 0.7 L/min. The trending ability of ICO was determined using the half-circle polar plot method where the mean radial bias, the standard deviation of the polar angle, and 95% confidence interval of the polar angle were -8º, ±17º, and ±33º, respectively.

This thesis provides a first description and proof-of-concept of iterative cardiac output measurement (ICO) – a respiratory, carbon-dioxide (CO2) based method of measuring cardiac output (CO). The ICO method continuously tests and refines an estimate of the CO by attempting to maintain the end-tidal CO2 constant. To validate the new method, ICO and bolus thermodilution CO (TDCO) were simultaneously measured in a porcine model of liver transplant. Linear regression analysis revealed the equation ICO = 0.69•TDCO + 0.65 with a Pearson correlation coefficient of 0.89. Analysis by the method of Bland and Altman showed a bias of -0.2 L/min with 95% limits of agreement from -1.1 to 0.7 L/min. The trending ability of ICO was determined using the half-circle polar plot method where the mean radial bias, the standard deviation of the polar angle, and 95% confidence interval of the polar angle were -8º, ±17º, and ±33º, respectively.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 147-157).

Orientador: Heitor Moreno Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-08T07:56:02Z (GMT). No. of bitstreams: 1 Martins_LuizClaudio_M.pdf: 906458 bytes, checksum: 5eca8eb707e90d3712220013fdc6e1f3 (MD5) Previous issue date: 2006 / Resumo: A vasopressina é um nonapeptídeo que possui moléculas de cisteína na posição um e seis ligadas por uma ponte dissulfeto, sendo sintetizada nos neurônios localizados nos núcleos supraópticos e paraventriculares do hipotálamo e transportada para a hipófise posterior onde é armazenada em forma de grânulos. A vasopressina tem seu efeito vasopressor conhecido deste o final do século XIX. Sua secreção é complexa, sendo liberada em situações de choque, hemorragias, síncope vagal, entre outras. Possui três tipos de receptores (V1, V2 e V3), sendo que o receptor V1 fica localizado nos vasos sanguíneos e é responsável pelo efeito vasoconstritor. Mais recentemente, o uso da vasopressina como medicação coadjuvante às catecolaminas no tratamento do choque vasodilatatório vem sendo descrito. A vasopressina normaliza a pressão arterial possibilitando que as doses de catecolaminas sejam diminuídas. É descrito que o uso da vasopressina em situações de choque é também associado a efeitos colaterais, como isquemia de mucosas, pele e miocárdica. O uso clínico rotineiro da vasopressina é muito limitado, sendo pouco conhecidas as doses que devem ser usadas para melhorar a hemodinâmica sem prejudicar a oferta tecidual de oxigênio. Neste estudo foi investigado os efeitos hemodinâmicos da vasopressina, em doses progressivas em cães anestesiados. Dezesseis cães sem raça definida, foram anestesiados e distribuídos aleatoriamente em dois grupos: Controle e Vasopressina. O grupo Vasopressina recebeu vasopressina nas doses 0,01 ; 0,1 e 1,0 U/kg/min por 10 minutos. Após a infusão foi realizado estudo hemodinâmico. Nas doses de 0,1 e 1,0 U/kg/min observou-se diminuição do índice cardíaco e da freqüência cardíaca, aumento da pressão arterial média e do índice de resistência vascular sistêmica. Na dose de 1,0 U/kg/min observou-se aumento do índice da resistência vascular pulmonar. Os resultados nos permitem concluir que a vasopressina pode ser útil nomanuseio do choque vasoplégico. Porém, a possibilidade de ocorrência de efeitos cronotrópicos e inotrópicos negativos podem deteriorar o estado metabólico no choque / Abstract: Introduction: Vasopressin is a neuropeptide with potent vasoconstrictor effect, but clinical experience with vasopressin in continuous infusion has been limited. In this study, we investigated the effects of vasopressin in continuous infusion on hemodynamic parameters in anesthetized dogs. Material and Methods: Mongrel dogs (n = 16) anesthetized and randomized in two groups: control and vasopressin. The vasopressin group received the following doses: 0.01 U/kg/min, 0.1 U/kg/min and 1.0 U/kg/min during 10 min. After infusion invasive hemodynamic study was performed. Results: Vasopressin continuous infusion in doses of 0.1 and 1.0 U/Kg/min for 10 minutes induced a significant decrease of heart rate and cardiac index, and significant increase of mean arterial pressure and systemic vascular resistance index. The 1.0 U/kg/min dose also induced a significant increase of pulmonary vascular resistance index. Conclusion: Increase of MAP and SVRI suggest vassopressin might be useful in managing a state of vasoplegic shock, however negative inotropic and chronotropic effects will also occur, what may deteriorate the metabolic state in a vasoplegic shock. Clinical experience utilizing vasopressin in vasoplegic shock is limited, as well as which dose should be used to minimize its deleterious effects / Mestrado / Mestre em Farmacologia