Anesthesia for End-Stage Respiratory Disease

 

Severe

Very severe impairment = end-stage respiratory disease

Inscription to a list of lung transplantation

FEV1 test

30 < FEV1 <49%

FEV1 <30%

FEV1 <20%

6-MWT

<200 m

Stable SpO2

< 100 m

Drop in SpO2 <4%

Drop in SpO2 >4%

Arterial gas

Normal pH with normocapnia

Hyperbaric

Hyperbaric

Eventual acidosis

Clinical symptoms

None or minor (cough, shortness of breath)

Shortness of breath during exercise or at rest

Need of oxygen during the day

Constant shortness of breath

Need of oxygen


FEV1 forced expiratory volume in 1 s, 6-MWT 6-min walk test, SpO 2 saturation in oxygen



Origins of end-stage respiratory failure concern many respiratory pathologies as in a decreasing order of occurrence:



  • Post-tobacco emphysema


  • Severe COPD


  • Fibrosis or cystic fibrosis


  • Interstitial lung disease


  • Obliterative bronchiolitis after immunosuppressive treatments or after transplantation


  • Chronic ARDS but this entity will not be affordable in this article



9.2 Preoperative Assessment



9.2.1 General Health


The most important way of assessment remains clinical with an estimation of patient’s autonomy in his daily life. This could be measured by the (I)ADL scale which explored different common actions as the ability to wear, to eat, etc. Impairment in autonomy is strongly associated with a poor outcome [2].

Then objective criteria can stratify the severity of the disease. One of the most important is advanced age (>60 years old) with the presence of any other comorbidity (systemic hypertension, neurological ischemic event, etc.). As described in Table 9.1, clinical symptoms of acute core pulmonary or right ventricle failure mean poor prognosis. In this circumstance a complete and current cardiac exam is required because in case of right ventricle hypertrophy, cardiac output is only on the dependency of its function and tolerance. Any source of ischemia (uncompleted stenosis of the right coronary artery) may quickly impair cardiac output with a rapid organ ischemia and lactic acidosis. Morphologic heart exam is required and should be completed by a coronarography to ensure the absence of coronary lesion. If a major repair is scheduled, tolerance during an effort should be measured through stress echocardiography or stress RMI. This complete assessment aims to decide the best anesthesia and analgesia strategy before surgery. At last, respiratory function is assessed. Shunt level and severity of hypoxemia are strong predictors of the functional “reserve” of lungs. Moreover, loss in the control of the pH is a sign of a quick decompensation, and it may indicate a delay in the surgery [3].

As every preoperative visit, the main aim is to perform a complete exam of comorbidities (Charlson score) with an accurate pre-anesthetic strategy. Risk of anemia or unexpected bleeding is crucial due to the linked risk of ischemia. In the other hand, any alternative to avoid a depression of the respiratory function should be counseling: local or regional anesthesia, limitation of mechanical stretch, non invasive ventilation support. In case of a scheduled lung surgery, a respiratory functional test should demonstrate a postoperative VEMS above 30%. A lower value is associated with a very high risk of complication with difficulty to wean the patient from the mechanical ventilation [3].

In some conditions, discussion about lung transplantation is open. In an attempt to balance the scarcity of donors and maximize societal benefit of lung transplantation, the indications for lung transplant have been updated to denote greater attention paid to the potential life years gained. It is now recommended that lung transplant only be considered in patients with >50% risk of death from lung disease within 2 years without transplant, >80% chance of a 90-day survival after transplant, and >80% expected a 5-year survival with transplant from general medical perspective, provided adequate graft function.


9.2.2 Preoperative Optimization



9.2.2.1 Breath or Pulmonary Rehabilitation


Rehabilitation can improve overall functional status acting primary on the muscle mass which is decreased due to a poor nutritional status with severe catabolism and decreased in the daily activity. In this situation, production of lactic acid and of carbon dioxide and ventilator demand are decreased for a similar effort. This benefit is particular for end-stage COPD, and this program includes smoking cessation, better detection of pulmonary exacerbation, and compliance to treatment.

In COPD, pulmonary rehabilitation program have been shown to significantly improve exercise capacity and health-related quality of life while reducing the severity of dyspnea. In a study led by Cesario et al., rehabilitation was able to change the status of patients with an improvement in respiratory function and allow them to be operated without complications in comparison to a control group [4]. This program is less well studied for other causes of end-stage respiratory disease. A clinical trial (NCT 1893008) still under recruiting status specifically studies the preoperative inspiratory muscle training through a tapered flow resistive inspiratory loading device. This program is tailored individually. Starting inspiratory load is aimed at 60% of the measured maximal inspiratory pressure. The load is incrementally increased based on the rate of perceived exertion, and patients have to complete 30 dynamic inspiratory efforts twice a day [5].


9.2.2.2 Concept of Prehabilitation


Prehabilitation includes the whole care pathway in the preoperative period whose aim is the health improvement of the “future” surgical or oncologic patient. In this meaningful, the increase in muscle mass and muscle tolerance should compensate the expected loss of muscle during the hospital length of stay. This concept precedes rehabilitation program supported by the ERAS society around the world and includes at the minimum three components: repeated series of aerobic and anaerobic exercises during the week (three times at most) with a devoted coach (physiotherapist or sport doctor), a diet optimization (reduction of sarcopenia, daily protein intake of 1–1.5 g/kg), and a psychological support. This interest in the preoperative period was promoted by Carli et al. at McGill University with a minimal duration of 4 weeks before the surgery [6].

Feasibility of such a multidimensional program was previously demonstrated in colorectal cancer. Therefore, an increase in the functional capabilities was observed with a gain of 10% in VO2 peak and in the 6-min walk test (6-MWT) as reference [7]. For responders, two consequences were described. First, this gain was related to a significant decrease in the postoperative complications (2% vs. 18%) and a specific shape in their performance. Indeed, the improvement disappears during hospital stay and secondly re-ups within 2 months. Finally, patients recover similar performances than preoperatively. At the opposite, control patients have a progressive impairment in their physical performances in the preoperative period and continuously alter their functional status in the postoperative period with a long and uncomplete recovery. They never reach their basal status. Compliance in the program seems really important as demonstrated by Coats et al. on patients scheduled for lung surgery [8]. A recent interesting report was performed after neoadjuvant radiotherapy for rectal cancer by West et al. and showed similarity with a significant decrease in the functional status during radiotherapy but a real improvement during the preoperative period in the prehabilitation group [9]. This concept needs further randomized controlled trial to achieve an undebatable demonstration even if many pilot studies give a common trend. Implementation of such a pathway in the surgical patient may encounter some barrier but we can imagine that the “temporal” window is not the same for end-stage respiratory patients. A previous study in which a partial program was proposed to severe COPD patients demonstrated a change in their functional status, and in this small cohort, patients were initially rejected from surgery and finally undergone it without any major complication or death in the postoperative period [4].


9.3 Conduct of Anesthesia



9.3.1 Preoxygenation


Preoxygenation should be used in any patient to anticipate difficult ventilation or intubation, and this recommendation especially concerns a patient who is hypoxic on air before induction. This time is essential to reduce the occurrence of hypoxemic event during induction related to an impaired passive oxygen delivery in case of thickening in the alveolar-capillary membrane. Some alternatives to improve oxygenation should be proposed to increase efficiency of preoxygenation.

First, a simple way to improve quality of preoxygenation is proclive position with recruitment of alveolar territories and more efficient diaphragmatic course. In patients with severe COPD and hypoxia, CPAP (continuous positive alveolar pressure) or pressure support ventilation (PSV) with PEEP during induction may be used to improve the efficacy of preoxygenation and reduce the development of atelectasis. This therapy was supported by some studies of emergent induction by Baillard et al. [10]. Therefore, NIV was associated with a low occurrence of drop in SpO2 compared to standard care: 93 ± 8% vs. 81 ± 15%, p < 0.001. Current studies suggest high flow of oxygen as a new way to optimize oxygenation during spontaneous ventilation while introducing a low PEEP and during apnea through passive transfer of oxygen to the alveolar. A great multicenter trial demonstrated that high flow of oxygen had a place in severe ill patients to optimize alveolar oxygenation [11]. This study confirmed the previous one comparing non-rebreather reservoir bag mask and high-flow nasal oxygen during intubation with a significant lower incidence of desaturation: 2% vs. 14%, p = 0.03 [12].


9.3.2 Regional Anesthesia


It is accepted that general anesthesia through tracheal intubation and intermittent positive pressure ventilation (IPPV) is associated with adverse outcomes in patients with COPD, fibrosis, or bronchiolitis. Such patients are prone to bronchial and tracheal hyper-responsiveness, cardiovascular instability, barotraumas, hypoxemia, and high rate of postoperative pulmonary complications. There is now increasing evidence to support the use of regional techniques in cases traditionally thought possible only under general anesthesia. One study found a 50% reduction in the risk of postoperative pneumonia in COPD patients when surgery was conducted with epidural anesthesia alone. The use of noninvasive ventilation (NIV) intraoperatively may also be used to ameliorate the respiratory exchanges [4]. Controversy remains over the use of interscalene brachial plexus block in patients with end-respiratory disease with a risk of diminished respiratory function resulting to phrenic nerve palsy. It is possible that better use of ultrasound guidance will minimize the volume of local anesthetic required and so may reduce the incidence of phrenic nerve involvement. To improve NIV and control pain in the postoperative course, use of epidural analgesia may be recommended.


9.3.3 Choice of Anesthetics for General Anesthesia


In a similar manner than the brain in extreme ages, some data suggest differences among anesthetics on postoperative lung complications (pneumoniae, atelectasis, etc.). Indeed, ischemia-reperfusion (IR) process may increase a primary inflammatory response which is different according to the anesthetic agents: halogenated volatile agents (Sevorane or desflurane) or intravenous agent—propofol [13]. Concerning volatile, their interests come from a direct infusion in the alveolar compartment before crossing the alveolar-capillary membrane to reach plasma, thanks to their high lipophilic profile. On the other hand, propofol has an optimal bioavailability especially in a high-risk situation of gas lack during one-lung ventilation because liver metabolism is controlled. Some studies have demonstrated a benefit for halogenated anesthesia with a reduction in the production of pro-inflammatory mediators in experimental or clinical studies. In clinical practice no direct relationship with postoperative outcome was found between anesthetics except in one. The role of volatile anesthetics inhibiting inflammatory response was firstly suggested by Schilling et al. who compared propofol administration and halogenated volatile in clinical setting of OLV. In these experiments bronchoalveolar lavage and blood analysis were performed and showed a compartmentalized response with a predominant ipsilateral response to ischemia. Therefore pro-inflammatory cytokines increased in the ventilated lung after OLV whatever the agents. But mediator release was about twofold more enhanced during propofol anesthesia compared with desflurane or sevoflurane administration [14]. As it concerns propofol, some studies suggest a positive impact on lipid peroxidation reactions caused by release of oxygen free radicals and inhibit the release of inflammatory mediator IL-8 and decrease the respiratory index. Therefore, results are still controversial, and one large review currently published drew a more favorable balance for halogenated agents. This review was based on eight studies on 350 patients undergoing OLV for thoracic surgery with protective effects via attenuating inflammatory responses [15].


9.3.4 Decision of Extubation


Before extubation, it is important to optimize the patient’s condition. The neuromuscular blocking agent should be fully reversed and the patient warm, well oxygenated, and with a PaCO2 close to the normal preoperative value for the patient. Peri-extubation bronchodilator treatment may be helpful. Extubation of the high-risk patient directly to noninvasive ventilation may reduce the work of breathing and air trapping and has been shown to reduce the need for reintubation in the postoperative period after major surgery.

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Dec 18, 2017 | Posted by in Uncategorized | Comments Off on Anesthesia for End-Stage Respiratory Disease

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