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Thiboutot J, Brown RH. Breathing Life into Pulmonary Physiology: How Age and Body Weight Impair Oxygenation. Anesthesiology 2019; 131:7-9. [PMID: 31045895 DOI: 10.1097/aln.0000000000002710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Jeffrey Thiboutot
- From the Department of Medicine (J.T., R.H.B.) Department of Anesthesiology and Critical Care Medicine (R.H.B.) Department of Environmental Health and Engineering (R.H.B.) Department of Radiology (R.H.B.), Johns Hopkins University, Baltimore, Maryland
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Abstract
Abstract
Editor’s Perspective
What We Already Know about This Topic
What This Article Tells Us That Is New
Background
Anesthesia is increasingly common in elderly and overweight patients and prompted the current study to explore mechanisms of age- and weight-dependent worsening of arterial oxygen tension (Pao2).
Methods
This is a primary analysis of pooled data in patients with (1) American Society of Anesthesiologists (ASA) classification of 1; (2) normal forced vital capacity; (3) preoxygenation with an inspired oxygen fraction (Fio2) more than 0.8 and ventilated with Fio2 0.3 to 0.4; (4) measurements done during anesthesia before surgery. Eighty patients (21 women and 59 men, aged 19 to 69 yr, body mass index up to 30 kg/m2) were studied with multiple inert gas elimination technique to assess shunt and perfusion of poorly ventilated regions (low ventilation/perfusion ratio []) and computed tomography to assess atelectasis.
Results
Pao2/Fio2 was lower during anesthesia than awake (368; 291 to 470 [median; quartiles] vs. 441; 397 to 462 mm Hg; P = 0.003) and fell with increasing age and body mass index. Log shunt was best related to a quadratic function of age with largest shunt at 45 yr (r2 =0.17, P = 0.001). Log shunt was linearly related to body mass index (r2 = 0.15, P < 0.001). A multiple regression analysis including age, age2, and body mass index strengthened the association further (r2 = 0.27). Shunt was highly associated to atelectasis (r2 = 0.58, P < 0.001). Log low showed a linear relation to age (r2 = 0.14, P = 0.001).
Conclusions
Pao2/Fio2 ratio was impaired during anesthesia, and the impairment increased with age and body mass index. Shunt was related to atelectasis and was a more important cause of oxygenation impairment in middle-aged patients, whereas low, likely caused by airway closure, was more important in elderly patients. Shunt but not low increased with increasing body mass index. Thus, increasing age and body mass index impaired gas exchange by different mechanisms during anesthesia.
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De Jong A, Futier E, Millot A, Coisel Y, Jung B, Chanques G, Baillard C, Jaber S. How to preoxygenate in operative room: healthy subjects and situations "at risk". ACTA ACUST UNITED AC 2014; 33:457-61. [PMID: 25168301 DOI: 10.1016/j.annfar.2014.08.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Intubation is one of the most common procedures performed in operative rooms. It can be associated with life-threatening complications when difficult airway access occurs, in patients who cannot tolerate even a slight hypoxemia or when performed in patients at risk of oxygen desaturation during intubation, as obese, critically-ill and pregnant patients. To improve intubation safety, preoxygenation is a major technique, extending the duration of safe apnoea, defined as the time until a patient reaches an arterial saturation level of 88% to 90%, to allow for placement of a definitive airway. Preoxygenation consists in increasing the lung stores of oxygen, located in the functional residual capacity, and helps preventing hypoxia that may occur during intubation attempts. Obese, critically-ill and pregnant patients are especially at risk of reduced effectiveness of preoxygenation because of pathophysiological modifications (reduced functional residual capacity (FRC), increased risk of atelectasis, shunt). Three minutes tidal volume breathing or 3-8 vital capacities are recommended in general population, mostly allowing achieving a 90% end-tidal oxygen level. Recent studies have indicated that in order to maximize the value of preoxygenation (i.e, oxygenation stores) obese and critically-ill patients can benefit from the combination of breathing 100% oxygen and non-invasive positive pressure ventilation (NIV) with end-expiratory positive pressure (PEEP) in the proclive position (Trendelenburg reverse). Recruitment manoeuvres may be of interest immediately after intubation to limit the risk of lung derecruitment. Further studies are needed in the field of preoxygenation in pregnant women.
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Affiliation(s)
- A De Jong
- Unité Inserm U1046, Anesthesiology and Intensive Care, Anesthesia and Critical Care Department B, Saint-Eloi Teaching Hospital, Université Montpellier 1, Université Montpellier 2, CHU de Montpellier, 80, avenue Augustin-Fliche, 34295 Montpellier, France
| | - E Futier
- Département d'Anesthésie et Réanimation, Hôpital Estaing, Université de Clermont-Ferrand, 1, rue Lucie-Aubrac, 63100 Clermont-Ferrand, France
| | - A Millot
- Unité Inserm U1046, Anesthesiology and Intensive Care, Anesthesia and Critical Care Department B, Saint-Eloi Teaching Hospital, Université Montpellier 1, Université Montpellier 2, CHU de Montpellier, 80, avenue Augustin-Fliche, 34295 Montpellier, France
| | - Y Coisel
- Unité Inserm U1046, Anesthesiology and Intensive Care, Anesthesia and Critical Care Department B, Saint-Eloi Teaching Hospital, Université Montpellier 1, Université Montpellier 2, CHU de Montpellier, 80, avenue Augustin-Fliche, 34295 Montpellier, France
| | - B Jung
- Unité Inserm U1046, Anesthesiology and Intensive Care, Anesthesia and Critical Care Department B, Saint-Eloi Teaching Hospital, Université Montpellier 1, Université Montpellier 2, CHU de Montpellier, 80, avenue Augustin-Fliche, 34295 Montpellier, France
| | - G Chanques
- Unité Inserm U1046, Anesthesiology and Intensive Care, Anesthesia and Critical Care Department B, Saint-Eloi Teaching Hospital, Université Montpellier 1, Université Montpellier 2, CHU de Montpellier, 80, avenue Augustin-Fliche, 34295 Montpellier, France
| | - C Baillard
- EA 3409, Department of Anesthesiology and critical care medicine, Avicenne university hospital, Paris-13 university, AP-HP, 125, route de Stalingrad, 93009 Bobigny, France
| | - S Jaber
- Unité Inserm U1046, Anesthesiology and Intensive Care, Anesthesia and Critical Care Department B, Saint-Eloi Teaching Hospital, Université Montpellier 1, Université Montpellier 2, CHU de Montpellier, 80, avenue Augustin-Fliche, 34295 Montpellier, France.
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Goldberg JS. Atherosclerosis: Viewing the Problem from a Different Perspective Including Possible Treatment Options. Lipid Insights 2011. [DOI: 10.4137/lpi.s7912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
This paper proposes that atherosclerosis is initiated by a signaling event that deposits calcium hydroxyapatite (Ca-HAP). This event is preceded by a loss of mechanical structure in the arterial wall. After Ca-HAP has been deposited, it is unlikely that it will be reabsorbed because the solubility product constant (Ksp) is very small, and the large stores of Ca+2 and PO4−3 in the bones oppose any attempts to dissolve Ca-HAP by decreasing the common ions. The hydroxide ion (OH–) of Ca-HAP can be displaced in nature by fluoride (F–) and carbonate (CO3−2) ions, and it is proposed that anions associated with cholesterol ester hydrolysis and, in very small quantities, the enolate of 7-ketocholesterol could also displace the OH– of Ca-HAP, forming an ionic bond. The free energy of hydration of Ca-HAP at 310 K is most likely negative, and the ionic radii of the anions associated with the hydrolysis of cholesterol ester are compatible with the substitution. Furthermore, examination of the pathology of atherosclerotic lesions by Raman and NMR spectroscopy and confocal microscopy supports deposition of Ca-HAP associated with cholesterol. Investigating the affinity of intermediates of cholesterol hydrolysis for Ca-HAP compared to lipoproteins such as HDL, LDL, and VLDL using isothermic titration calorimetry could add proof of this concept and may lead to the development of a new class of medications targeted at the deposition of cholesterol within Ca-HAP. Treatment of acute ischemic events as a consequence of atherosclerosis with denitrogenation and oxygenation is discussed.
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Affiliation(s)
- Joel S. Goldberg
- Pharmacy and Therapeutics Committee, Durham Veterans Affairs Medical Center, Duke University School of Medicine, 508 Fulton Street, Durham, NC 27705
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