"Closing volume" and its relationship to gas exchange in seated and supine positions.

Craig, Douglas B.; Wahba, W. M.; Don, H F; Couture, Jacques; Becklake, Margaret R.

doi:10.1152/jappl.1971.31.5.717

Cited by 214 publications

(81 citation statements)

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“…Awake older non-anesthetized patients have less efficient gas exchange compared to younger subjects, as shown by the increase in both A-aDO 2 and physiologic pulmonary shunt ( Figure 5A). Supine positioning for anesthesia induces a further decrease in FRC (Figure 2), 24 and the arterial oxygenation appears to be related to the relationship between preoperative closing capacity and intraoperative FRC. 44 Alveolar gas exchange during anesthesia is less efficient in the elderly ( Figure 5B) and an inverse relationship exists between the increased age and arterial oxygenation in spontaneously breathing patients.…”

Section: Mechanisms Of Postoperative Pulmonary Complicationsmentioning

confidence: 95%

“…Arterial oxygenation gradually declines with aging, 24 whereas CO 2 elimination remains unaffected despite an increase in dead space ventilation. 25 The latter is due at least in part to a decline in CO 2 production associated with a decrease in basal metabolic rate.…”

Section: Gas Exchangementioning

confidence: 99%

“…81 In addition to these maneuvers, postoperative care of elderly patients should always include early mobilization, as well as the liberal use of more upright positions that increase FRC and may significantly improve gas exchange. 24 …”

Section: Lung Expansion Maneuvers (Incentive Spirometry Intermittentmentioning

confidence: 99%

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Review article: Age related alterations in respiratory function — anesthetic considerations

Šprung

Gajic

Warner

2006

Can J Anesth/J Can Anesth

143

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Purpose: This review examines the effect of aging on pulmonary reserve. Special emphasis is placed on how anesthetic and surgical factors may impose substantial stresses on the respiratory system of elderly patients, leading to increased risk for postoperative pulmonary complications including respiratory failure.Source: A MEDLINE-based English-language literature search was undertaken for the period 1966-2006, and an EMBASE search covered the overlapping period 1988-2006. Selected articles were limited to those applying to elderly subjects/patients. Principal findings:Age-related loss of the lung static recoil forces, stiffening of the chest wall and diminished alveolar surface area lead to a decrease in vital capacity, an increase in residual volume, decrease in expiratory flows and increased ventilation-perfusion heterogeneity. Respiratory muscle strength consistently declines with age further increasing the work of breathing. While gas exchange may be well preserved at rest and during exertion, pulmonary reserve is diminished, and under conditions of positive fluid balance, positioning for surgery, and increased metabolic demand, postoperative respiratory failure can occur. Increased sensitivity to respiratory depressants and muscle weakness pose additional risks for the development of postoperative respiratory complications in elderly patients. Regional anesthetic techniques provide for superior postoperative analgesia, without necessarily altering the frequency of postoperative pulmonary complications in the older surgical population. Conclusion:Alterations in respiratory physiology associated with aging must be appreciated to anticipate and minimize potential complications associated with surgery and anesthesia in the elderly. Individualized care to optimize preoperative cardiorespiratory function, minimize intraoperative respiratory pertubations, and to gently restore postoperative pulmonary function are essential anesthetic goals for elderly patients who require surgery. Objectif

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Section: Mechanisms Of Postoperative Pulmonary Complicationsmentioning

confidence: 95%

Section: Gas Exchangementioning

confidence: 99%

See 1 more Smart Citation

Review article: Age related alterations in respiratory function — anesthetic considerations

Šprung

Gajic

Warner

2006

Can J Anesth/J Can Anesth

143

View full text Add to dashboard Cite

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“…The V50 /V25 ratio as an index of small airway impairment (Takishima et al 1972) was also calculated. Closing volume (CV) was obtained with the single N2 washout test (Craig et al 1971). The percentage of CV to VC (CV%) was calculated.…”

Section: Pulmonary Function Testsmentioning

confidence: 99%

Small Airway Involvement in Mixed Connective Tissue Disease.

Izumiyama

Hida

Ichinose

et al. 1993

Tohoku J. Exp. Med.

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We studied pulmonary functions in 17 female patients with mixed connective tissue disease (MCTD) to detect early pulmonary involvement in this disease; in 8 of the 17 patients followup studies were also performed at 1.2-to 5.9-year intervals. In the first pulmonary function tests, decreases in vital capacity (VC) and diffusing capacity (DL~o) were observed in 6 (35%) and 8 (47%) patients, respectively. The ratio of forced expiratory volume in one second to VC was normal in all the patients, but pulmonary resistance and static compliance were abnormal in 6 (35%) and 10 (59%) patients, respectively. However, frequency dependence of dynamic compliance was found in all 16 patients tested. Moreover, 4 (24%) of the 17 patients had normal DL~o and DL~o-to-alveolar volume ratio (DLCO/VA). Reductions in DL~o and DLCo/VA were significantly correlated with the disease duration. These results suggest that small airway obstruction is an early and frequent indication of functional pulmonary impairment, and that impairment of alveolar gas exchange is progressive in patients with MCTD.connective tissue disease; small airways; frequency dependence of dynamic compliance; diffusing capacity

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“…Por ser um método em que a pressão positiva aplicada pode ser menor do que na ventilação convencional, a pressão de vias aéreas gerada será menor, reduzindo os riscos de barotrauma e/ou volutrauma e de alterações cardiocirculatórias importantes 4,6,17 . Uma vantagem adicional é a de que o paciente consegue manter os ciclos respiratórios espontâneos em ambos os níveis de pressão, permitindo um melhor sincronismo com o aparelho de ventilação pulmonar mecânica e reduzindo a necessidade da utilização de sedativos/opióides e relaxantes musculares 10 .…”

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Liberação de pressão de vias aéreas em pacientes pediátricos submetidos à cirurgia cardíaca

Carvalho¹,

Kopelman²,

Gurgueira³

et al. 2000

Rev. Assoc. Med. Bras.

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Resumo -OBJETIVO. Comparar três modos de VPM, a ventilação mandatória intermitente com pressão expiratória positiva (VMI+PEEP), a VLPVA e a utilização de pressão positiva contínua em vias aéreas (CPAP) em crianças no pós-operatório de cirurgia cardíaca com hipertensão pulmonar e lesão pulmonar leve ou moderada.MÉTODOS INTRODUÇÃONos pacientes com lesão pulmonar aguda e complacência pulmonar diminuída, a utilização da pressão positiva contínua em vias aéreas (CPAP) está indicada com o objetivo de melhorar a capacidade residual funcional (CRF) e promover uma melhor oxigenação 12 . Porém, em determinados pacientes com hipercapnia, somente isto não é suficiente, pois não ocorre melhora da ventilação alveolar e, habitualmente, emprega-se a ventilação pulmonar mecânica convencional com a utilização da ventilação mandatória intermitente (VMI), o que acarreta uma elevação significativa da pressão média das vias aéreas aumentando o risco de barotrauma e/ou volutrauma e o de alterações cardiocirculatórias 20,11,16 .Conforme descrito por Stock M. C. e Downs J. B. em 1987, a ventilação com liberação de pressão de vias aéreas (VLPVA) constitui um novo modo de ventilação pulmonar mecânica empregando um fluxo contínuo onde uma pressão positiva é aplica- CONCLUSÕES. Devido à metodologia empregada, houve um aumento significativo da PMVA na VLPVA, com conseqüente aumento do VC e manutenção das outras variáveis respiratórias e cardiocirculatórias quando comparados os três modos de VPM, indicando ser a VLPVA um méto-do seguro e de fácil aplicação.UNITERMOS: Ventilação pulmonar mecânica. Respiração artificial. Insuficiência respiratória. Pediatria. da nas vias aéreas (nível de CPAP 2 ) e periodicamente é liberada para uma pressão menor ou até mesmo para pressão atmosférica, permitindo, com isso, a exalação passiva de ar para níveis de pressão intraalveolar menores (CPAP 1 ), promovendo a saída de CO 2 e melhorando a ventilação alveolar 23 (Fig. 1).Este modo de ventilação torna-se possível através de um sistema com uma válvula solenóide que ao ser fechada permite que um fluxo contínuo de gás promova uma pressão positiva contínua em vias aéreas determinada pela resistência da via de saída (válvula de CPAP). Posteriormente, com a abertura da válvula solenóide, durante um intervalo de tempo específico, há uma queda imediata da pressão de via aérea fazendo com que ocorra a exalação 9 (Fig. 2).Por ser um método em que a pressão positiva aplicada pode ser menor do que na ventilação convencional, a pressão de vias aéreas gerada será menor, reduzindo os riscos de barotrauma e/ou volutrauma e de alterações cardiocirculatórias

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"Closing volume" and its relationship to gas exchange in seated and supine positions.

Cited by 214 publications

References 0 publications

Review article: Age related alterations in respiratory function — anesthetic considerations

Review article: Age related alterations in respiratory function — anesthetic considerations

Small Airway Involvement in Mixed Connective Tissue Disease.

Liberação de pressão de vias aéreas em pacientes pediátricos submetidos à cirurgia cardíaca

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