Evren Şentürk, Funda Gök, Mert Şentürk This chapter focuses principally on the organization of postoperative care of the thoracic patient. Unfortunately, evidence-based guidelines regarding this period is not well-defined or supported by a sufficient number of studies addressing the different challenges. The anesthesiologist is an important part of the multidisciplinary context of perioperative medicine, directly involved in the decisions made during the pre-and intraoperative periods which can affect the postoperative outcome. One of such decisions is the question where to send the patient after surgery: Scoring systems do not help much while local conditions play an important role; overall, there is a decrease in the requirement of the intensive care unit for postoperative care. Enhanced Recovery After Surgery (ERAS) protocols have obtained a very important new step to help the philosophy of perioperative medicine; current ERAS protocols for thoracic surgery are welcome (constituting another chapter in this book); but unfortunately, still more suggestion-based than evidence-based. Management of chest tubes is another postoperative issue where newer suggestions aim to achieve a faster recovery without increasing the risk. Improvements in technology help to deal with the challenges: Regarding the postoperative period, two new tools have to be underlined: Ultrasound is now used routinely for many purposes, with abilities and advantages beyond chest x-ray. Thermodilution techniques have been considered to have very limited—if any—indications; current findings have shown that it can be helpful for evaluation of the right ventricular function. These devices and new studies can change our paradigms regarding the fluid therapy to keep the patient safely in euvolemic status. The scope of these innovations is also beyond the fluid therapy. Mechanical ventilation is unphysiologic, and can cause complications (ventilator associated lung injury [VALI] and ventilator associated pneumonia [VAP]). Therefore it is indicated only in patients in whom a gas exchange is indeed impossible with other approaches. In these cases, ventilation should be even more protective than general suugestions: even lower tidal volumes, rather no recruitment maneuver etc. To avoid the disadvantages of mechanical ventilation, newer approaches, such as noninvasive ventilation and high-flow oxygen therapy are now used more frequently. In most extreme cases, exceptional solutions like extracorporeal lung support or differential lung ventilation can be indicated. As patients after thoracic surgery comprise a spesific group for mechanical ventilation, weaning also plays a more important role. Each center has to define a protocol for weaning, based both on scientific evidence and on center-specific prerequisites. Electronic data recording systems can help to follow these protocols. postoperative care; fluid management; lung ultrasound; protective ventilation; noninvasive ventilation; high-flow oxygen treatment; differential lung ventilation; extracorporeal lung support; weaning; ventilator-associated pneumonia Anesthesiologists are responsible for the management of the surgical cases not only during the intraoperative stage, but rather through the entire perioperative period. In the multidisciplinary context of perioperative medicine, anesthesiology is an important component in addressing the challenges from all practical, financial, and scientific points of view. Providing anesthesia to thoracic procedures is probably the prime example within the field of anesthesiology to have a crucial responsibility as a perioperative medicine physician. In general, the postoperative care of thoracic surgical patients is controlled by the intensive care unit (ICU) anesthesiologists either exclusively or as part of a multidisciplinary team with thoracic surgeons and pulmonologists. This chapter aims to review the postoperative care of the thoracic surgical patient. Postoperative complications, postoperative analgesia, as well as the postoperative part of the enhanced recovery after surgery (ERAS) protocol are discussed in Chapter 53 of the book. In recent years, there have been significant advances in surgery, anesthesia, and intensive care techniques; however, thoracic surgery is still associated with a high incidence of postoperative complications recently reported, as being 27%.1 That high complication rate can be attributed to the fact that patients who were not surgical candidate decades ago are now offered major resections. To decrease the high incidence of complications, enhanced recovery after thoracic surgery (ERATS) has been reported as a possible approach2: these recommendations should be considered as a very promising pioneer step with a beneficial philosophy, but it should be underlined that they are based rather on strong recommendations than scientific evidence; therefore it is not surprising that the ERAS pathway is available in different protocols, with similar, but not the same recommendations, from different centers in different countries.3–5 As a matter of fact, there are still very few obvious evidences to support any suggestion for possible challenges of the postoperative care after thoracic surgery. However, the philosophy of ERAS is very appropriate in that all the stages of the perioperative period, namely preoperative evaluation and preparation, intraoperative management, and postoperative care should focus on enhanced recovery with decreased complications. We want to underline as an important note that enhanced does not mean necessarily fast. There are still no clear cut criteria for deciding whether to send the patient to the ICU or the postanesthetic care unit (PACU). In the past, patients post thoracotomy were almost routinely sent to the ICU. However in recent years, it is progressively difficult to find available ICU beds which are more expensive but not necessarily more beneficial. In fact, it has been shown that although elective transfer to the ICU has reduced the total morbidity and frequency of complications it has not changed the mortality rate (7.3% vs. 7.3%); moreover, elective transfer to the ICU has caused a longer hospital stay.6 The increasing quality of the PACUs has ensured a cost-effective and reliable alternative for postoperative admission. The current trend is to move away from ICU admission and toward PACU or high dependency units (HDUs). In most institutions patients who undergo pneumonectomy, esophagectomy, or tracheal resection, are admitted to the ICU. In a recent retrospective study with 451 patients who underwent video-assisted thoracoscopic surgery (VATS) lobectomy, it has been shown that in selected patients (except: chronic obstructive pulmonary disease [COPD], nonstage I cancer, multiple port VATS, and age ≥60 years), selective intensive monitoring in the general ward—with the motto routine intensive monitoring but not routine intensive care—was safe and feasible without a poor outcome.7 Well-equipped units with appropriate monitoring would be a reasonable consideration when choosing the postoperative care location. Preoperative criteria for transferring a patient to the ICU will depend on the patient’s medical condition, the type and the extent of the surgical procedure, and the hospital organization. We propose that a standardized preoperative prediction of whether the patient will be sent to the ICU or the PACU will help to establish a more appropriate organization of patient care. An interesting recent study has shown that patients who had an unplanned admission to ICU had higher mortality (29% vs. 0.03%).8 In general, three factors affect the decision of the location of the postoperative care: patient-related risks (whereby modifiable and nonmodifiable factors should be evaluated), surgical risks, and intraoperative events which are usually unexpected. Some patient-related factors, such as age over 70 years, American Society of Anesthesiologists—score of 3 or more, fibrotic lung disease, or preoperative neoadjuvant chemotherapy are generally considered as potential indications for ICU admission.9,10 Surgical procedures, such as pneumonectomy, tracheal and bronchial resection, esophagectomies, lung volume reduction, and transplantation are considered (not exclusively) as high-risk operations. The difference between modifiable (e.g., smoking) and nonmodifiable factors (e.g., age) is the most clinically relevant measure; preoperative interventions on modifiable factors may decrease the need for ICU treatment.11 Some factors (e.g., preexisting lung disease, obesity, comorbidities, such as cardiovascular diseases, hypertension, diabetes mellitus) are partly modifiable. To achieve improvements in modifiable and partly modifiable factors, preoperative habilitation/prehabilitation programs have been shown to have a positive impact on the occurrence and severity of postoperative complications after thoracic operations by minimally invasive surgery.12 From this point of view it can be argued that the postoperative care of the thoracic patients starts in the preoperative period (see Chapter 9). Scoring systems13 and risk factor definitions have been reported in several studies and reviews, can be helpful in defining the composite of patient-related surgical risks and provide some objective criteria regarding the location of postoperative care. Although it can differ among different centers, the overall recommendations of different scoring systems regarding the decision for sending the patient to ICU are:14 The ARISCAT study has reported a risk score for the development of postoperative pulmonary complications (PPCs) includes seven independent risk factors,15 both patient-related and surgical risk factors, that contributed equally to global risk and has been shown to have a predictive power.16 This scoring system is being used for several studies and clinical practice today. Yet, there is still a big grey zone regarding the decision of the location of postoperative care of thoracic patients, because: Chest tubes are considered mandatory in all intrathoracic operations. Therefore the physician should be familiar with proper management of the thorax drainage, diagnosis, and treatment of its complications. Chest tubes remove air (ventral or cranial placement) and/or fluid (dorsal or caudal placement). Thus the physician’s goal is to monitor, prevent, or treat air leaks and excessive pleural drainage.17 Although digital chest drainage systems are being used increasingly since approximately 10 years, the principle of the classical 3-bottle chest tube drainage system (Fig. 26.1) should still be mastered by the clinician dealing with a postthoracotomy patient. The introduction of ERATS protocols has again shown the controversies in the management of chest tubes. There are several issues regarding the chest tube management: The air from the pleura can be sucked passively (with a water seal) or actively (with a wall suction). ERATS protocol2 sufficiently summarizes the pros and cons of both suction and the so-called water seal. The relationship between the suction approach and clinical outcome is relatively weak that it can be easily biased by other components of the protocol of chest tube management.18 Yet, there are some common approaches: After a thoracic procedure, blood drainage should be carefully monitored especially in the early phase, and excessive drainage should signal an emergency alarm to immediately contact the surgical team. There have been empirically determined thresholds (e.g., 200 or 250 mL/day) for chest tube removal, however these dogmas have been refuted with stronger studies showing that the chest tubes can be removed if the drainage is <450 mL/day as long as there is no air leak or cerebrospinal fluid, chyle, or blood in the fluid.19 Even a high drainage of 500 mL/day following VATS lobectomy resulted in an incidence of clinically relevant recurrent effusions, that needing drainage or aspiration, in only 2.8% of patients.20 Routine monitoring after thoracic surgery outside the ICU consists of continuous pulsated oximetry (SpO2) and chest x-ray (CXR) in predetermined certain times. However, this paradigm of routine CXR is subject to change: studies examining the advantages of routine daily CXR versus selective clinical evaluation were not able to report any change in mortality rate, hospital length of stay, or adverse events on the basis of schedule CXR,18 with the only exception in hypoxic patients. On the other hand, selective CXR only caused by clinical suspicion of a potential problem carries the risk of missing the initial phase of pulmonary complications. Low-radiation dose computer tomography (CT) allows reliable evaluation of pulmonary edema, but does not appear to be a widespread alternative because of the high cost, the risk of transport, and radiation exposure. Lung ultrasound (LUS) appears to solve the dilemma, in addition to its other advantages. Another challenge is the decision about optimal fluid management, as the fluid therapy has been a classical problem especially in the intra- and postoperative period of thoracic surgery. New techniques not only help to determine whether to give more fluids, they can also help to monitor right ventricle function. LUS is a quick, inexpensive, easy-to-use and—importantly—reliable imaging modality.23 It can diagnose cases of possible or undetected pneumothorax in CXR24 (Fig. 26.3A); as well as pulmonary edema, pleural effusion, subcutaneous emphysema, and pneumonia (Fig. 26.3B–D). In conjunction with limited information from cardiac or vascular ultrasound, LUS aids diagnosis of pulmonary embolism.25 The very basic knowledge of LUS evaluation has been defined by Lichtenstein.26 The pioneer of the protocols of this approach: in normal lung tissue, the interlobular septa are not detected by ultrasound and the pleural lines yield horizontal repetition artifacts, which have been termed the A-lines (Fig 26.3E). When the subpleural alveoli become edematous in the setting of increased extravascular lung water (EVLW), the resulting mixture of air and fluid yields the pathologic B-lines by ultrasound. These B-lines represent reverberation artifacts arising from the air-fluid interface between the fluid-filled and aerated alveoli26 (see Fig. 26.3B). There is a linear correlation of the numbers of B-lines and increasing EVLW that reaches from interstitial edema showing four to eight B-lines to severe states of the alveolar-interstitial syndrome (AIS) with the confluence of multiple B-lines to the appearance of white lung27 (see Fig. 26.3B and F). Sonographic appearance of AIS can also help to differentiate its possible causes, whereby a uniform distribution pattern of B-lines, with normal lung sliding and a high incidence of homogeneous appearing pleural effusions indicates left atrial hypertension and increased hydrostatic pressure. While in acute respiratory distress syndrome (ARDS) there are increased amounts of B-lines, seen in combination with pleural line abnormalities, lack of lung sliding, uneven tissue patterns like spared areas, consolidations, such as lung pulse and air bronchograms.28 Using transthoracic echocardiography (TTE), ventricular function can be evaluated. Especially right ventricular functions during and after thoracic surgery has been considered to be very difficult, and also often underestimated.29 Furthermore, the evaluation of the diaphragm with ultrasonography (DUS) may provide additional benefits to the clinician. A diaphragmatic dysfunction has been documented after thoracic surgery, as a condition that contribute to an increase in postoperative pulmonary complications.30,31 The diaphragmatic ultrasonography is a noninvasive method which can be performed at the bedside. For this purpose, the diaphragm is evaluated in two different ways. These include the functional evaluation of the diaphragmatic excursion (DE) and the diaphragmatic thickening (DT) fraction (Fig. 26.3G and H). In a study where DE was used for the functional evaluation of the diaphragm, it has been shown that the diaphragmatic dysfunction detected within the first 24 hours was associated with the PPC occurring within the first 7-day period. Spadaro et al. in a prospective study enrolled 75 patients undergoing VATS versus those undergoing thoracotomy. Diaphragmatic dysfunction was defined as a diaphragmatic excursion less than 10 mm. The ultrasound evaluations were carried out before (preoperative) and after (i.e., 2 hours and 24 hours postoperatively). The incidence of postoperative diaphragmatic dysfunction at 24 hours was higher in the thoracotomy group as compared with VATS group (83% vs. 55%, respectively). Patients with diaphragmatic dysfunction on the first day after surgery had higher percentage of PPCs (odds ratio = 5.5; 95% confidence interval [CI], 1.9–16.3; P = .001).32 Although there are few studies addressing the issue, the value of the available evidence indicates the significance of DUS and the need for further studies. Consequently, LUS should be considered as a beneficial diagnostic tool in the practice of postoperative thoracic surgery: It should be taken in account that for the patient undergoing thoracic surgery, abnormal anatomy because of preexisting diseases or changes because of surgery can limit the diagnostic value of LUS; preoperative LUS evaluation can be a rational approach to eliminate this limitation.23 Since Zeldin’s first definition of postpneumonectomy pulmonary edema (PPE), a series of studies have shown the direct relation of fluid overload in the perioperative period and the incidence of postoperative respiratory failure. Fluid therapy was considered as one of most critical challenges of perioperative care of thoracic surgery. It has been shown that fluid challenges often fail to increase the intravascular volume but instead results in fluid leakage into the interstitial space.33 Even the definitions of liberal and restrictive regimens differ essentially among different studies. The debate about different regimens like goal-directed therapy or zero-balance is true for all types of surgeries34,35 and the challenge is even more dramatic in thoracic surgery because of several additive factors. On the other hand, the thought of the less, the better is also not appropriate: the evidence of fluid restriction is weaker than its reputation: in fact, inadequate fluid administration can be associated with tissue hypoperfusion as seen in acute kidney injury and other end-organ failure.36 The assertion that lungs do not have a third space is accurate, yet one must be reminded that any other organ does not have a third space either, so that this elusive third space should be considered as an urban myth.37 Moreover, it has to be kept in mind that earlier studies that showed the relationship between high fluids administration and lung injury are often biased because many other factors, such as lung injury from mechanical ventilation with high tidal volumes, were applied. A very important pathophysiologic pathway of leakage of fluids into the interstitial space is the damage of endothelial glycocalyx,38 a fragile network structure lining the endothelium. Many factors (such as nonprotective mechanical ventilation, surgical trauma) have been reported to cause or at least associated with a damage of glycocalyx. Similar to ARDS and ventilator-associated lung injury, administering fluids is not the only cause; but may be a contributing factor to worsening symptoms of PPE. With intravenous fluids, we can make it worse, but we do not cause it.39 Fluid overload should be avoided both during andafter thoracotomies. Slinger has suggested a limit for the intraoperative period (<2 L), and limit the fluid to (<3 L) for the entire day of surgery.40 Newer guidelines suggest not to exceed the perioperative positive fluid balance of 1500 mL (or 20 mL/kg/24 hours).2 Hypotension during and after thoracotomy is only rarely caused by hypovolemia; it is more often caused by vasodilation (e.g., caused by thoracic epidural anesthesia.). Low doses of catecholamines would be more appropriate than more fluids considering that hypotension is likely caused by relative hypovolemia.41 Monitoring the fluid balance is mandatory, especially in patients at risk of acute lung injury (ALI). Pulmonary artery catheters have been almost entirely replaced by newer, noninvasive, such as LUS, or semi-invasive devices.23 Among them, the single-indicator transpulmonary thermodilution (TPTD) method can assess quantitatively the EVLW index (EVLWI)42 and can monitor cardiac output using pulse contour analysis of the arterial pressure.43 Pulse-pressure variation analysis can predict the fluid responsiveness also intraoperatively.44 Another method, called the pleth variability index, provides information about the volume status using the variations in pulse oximetry;45 the noninvasiveness of this method is advantageous and existing studies seem promising. There is a concern about usefulness of these techniques during OLV in both VATS and open thoracotomy. In spite of controversies, the majority of the studies report that stroke volume variation and pulse pressure variation are not useful for predicting fluid responsiveness in thoracic surgery.46 However, the postoperative period differs from the conditions of OLV, where the concern about the accuracy of single thermodilution measurement to estimate EVLW after lung resection was validated against double dye technique and found to be well correlated for up to 12 hours.47 Yet, TPTD also has some limitations: measurement takes place only in areas of perfused lungs, assuming there is a homogeneous distribution of pulmonary perfusion. That homogeneous distribution can be impaired by several perioperative factors, such as lung resection, hypoxic pulmonary vasoconstriction, and others.23 The ability to measure the EVLW has obtained a more rational fluid management. Indeed, EVLW was shown to be an independent predictor of survival in critically ill patients,48 so that the clinicians can change their historical approach of restrictive fluid management to achieving normovolemia with a goal-directed treatment.49 For patients with sepsis or ARDS, the threshold of EVLW appears to be between 8 and 9 mL/kg.42 Although the inhomogeneity in patients following thoracic surgery can make the decision more complicated, this threshold can still be helpful. Using the results of TPTD measurements in combination with LUS (changes between preoperative and postoperative LUS findings) can obtain more reliable decisions.23 The decision regarding the fluid treatment or vasoactive drugs should be based on several parameters as depicted in Box 26.1.42,49 The type of fluids is also a subject of discussion. As the indication of colloids, mainly hydroxy-ethyl starch (HES), is currently limited only to acute blood loss, their use in the postoperative period in PACU or in ICU appears to be the exception. Yet, it has to be kept in mind that most of the available data are not from thoracic patients, but extrapolated from studies performed on septic, critically ill patients in ICUs, or from patients undergoing cardiovascular surgery. In a retrospective study, the incidence of acute kidney injury (AKI) after thoracic surgery was found to be 5.1% (74 in 1442 patients). There was no correlation between crystalloid restriction and AKI; interestingly, AKI occurred more often when HES were administered to the patients with decreased renal function or having more than two risk factors with normal renal function. The authors concluded that HES should be administered with caution in high-risk patients undergoing thoracic surgery.36 Besides the drawback in patients with renal risks, this study limits the concern about HES only to these patients. Thoracic anesthesiologists tend to use HES in combination with balanced crystalloids (rather than saline), as part of a multimodal fluid resuscitation.2,49 It is well-known that there is a reduction of up to 25% in right ventricular ejection fraction (RVEF) following lung resection50 that can result in postoperative right ventricular (RV) dysfunction. The evaluation of RV and pulmonary vascular function has remained limited until recently because of the lack of a simple inexpensive technology to obtain reliable diagnostic criteria.51 Perioperative factors, such as preexisting pulmonary disease, ventilation strategies, including OLV and analgesia methods like thoracic epidural anesthesia, can all adversely affect RV function.52 Recently, the relationship between lung resection and RV dysfunction has been shown using cardiac magnetic resonance. McCall et al. evaluated 27 patients using cardiovascular magnetic resonance imaging to assess the RV response to lung resection. Cardiovascular magnetic resonance imaging with volume and flow analysis, preoperatively, on postoperative day 2 and at 2 months. They found that RVEF deteriorated from 50.5% ± 6.9% preoperatively to 45.6% ± 4.5% on postoperative day 2 and remained decreased at 44.9% ± 7.7% by 2 months (P = .003). They concluded that RV dysfunction occurs following lung resection and persists 2 months after surgery.53 In another study, the utility of TTE was examined to aid in the diagnosis of RV dysfunction following pulmonary resection.29 The studies show that RV dysfunction persists for up to 2 months postoperatively, and is more severe in patients undergoing pneumonectomy, whereas thoracoscopy may be protective. Using a relatively simple and noninvasive method like TTE can be helpful to put a new target in pre- and postoperative care of thoracic surgery. The prevention of RV dysfunction can change our current practice of mechanical ventilation, fluid management, and even postoperative analgesia. This section will focus on and limit itself to the specific features of ventilatory support in the postthoracotomy period. Postoperative ventilatory support is indicated when there are: There are two serious complications associated with postoperative mechanical ventilation: Mechanical ventilation as a method of treatment/prevention of respiratory failure can per se cause ALI (i.e., ventilatory-associated or -related lung injury).54 As relative newer methods like noninvasive ventilation (NIV) or high-flow oxygen (HFO) therapy have been introduced in practice, conventional mechanical ventilation is currently indicated in a limited group of patients, in whom—paradoxically—it can be even more hazardous: devil or the deep blue sea. The specific group of patients after thoracic surgery might have already undergone a multi-hit of ventilatory traumas by both thoracic surgeons and the anesthetists: surgeons remove larger parts of the lungs; in addition, they manipulate the remaining lung tissue in a traumatic way, and cause damage to the respiratory muscles. A thoracotomy is one of the most painful operations, which can cause further impaired ventilation. OLV can cause lung injury, especially if the OLV-management is inappropriate and nonprotective55; in addition, excessive fluid infusion and blood transfusion can further directly harm the lungs. Interestingly, the possibility of a postoperative lung injury in the nonsurgical dependent lung is higher than the surgical collapsed lung, indicating that the intraoperative ventilation affect the postoperative lung functions.56 Therefore in PACU or ICU, mechanical ventilation should be continued or restarted only if absolutely necessary; less invasive methods of respiratory support should be considered before indicating the invasive mechanical ventilation. The pathway of ventilatory support can be considered as a stairway, where in every step the risks increase (Fig. 26.5).
Postoperative Care of the Thoracic Patient
Abstract
Keywords
Introduction
Location and Structure of Postoperative Care: Intensive Care Unit, High-Dependency Unit or Postanesthetic Care Unit?
How Helpful Are the Scoring Systems to Predict the Postoperative Status Preoperatively?
Management of Chest Tubes
Specific Monitoring Tools
Lung Ultrasound as a New Tool (See Chapter 54)
Fluid Management and its Monitoring
Monitoring of Right Ventricular Function
Ventilatory Support for Patients After Thoracic Surgery
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Postoperative Care of the Thoracic Patient
