Major surgery is still associated with undesirable sequelae such as pain, cardiopulmonary, infective and thromboembolic complications, cerebral dysfunction, nausea and gastrointestinal paralysis, fatigue and prolonged convalescence. The key pathogenic factor in postoperative morbidity, excluding failures of surgical and anaesthetic technique, is the surgical stress response with subsequent increased demands on organ function. These changes in organ function are thought to be mediated by trauma-induced endocrine metabolic changes and activation of several biological cascade systems (cytokines, complement, arachidonic acid metabolites, nitric oxide, free oxygen radicals, etc). To understand postoperative morbidity it is therefore necessary to understand the pathophysiological role of the various components of the surgical stress response and to determine if modification of such responses may improve surgical outcome. While no single technique or drug regimen has been shown to eliminate postoperative morbidity and mortality, multimodal interventions may lead to a major reduction in the undesirable sequelae of surgical injury with improved recovery and reduction in postoperative morbidity and overall costs.

Multimodal approach to control postoperative pathophysiology and rehabilitation.

Objective: To evaluate the effect of modifying perioperative care in noncardiac surgical patients on morbidity, mortality, and other outcome measures. Background: New approaches in pain control, introduction of techniques that reduce the perioperative stress response, and the more frequent use of minimal invasive surgical access have been introduced over the past decade. The impact of these interventions, either alone or in combination, on perioperative outcome was evaluated. Methods: We searched Medline for the period of 1980 to the present using the key terms fast track surgery, accelerated care programs, postoperative complications and preoperative patient preparation; and we examined and discussed the articles that were identified to include in this review. This information was supplemented with our own research on the mediators of the stress response in surgical patients, the use of epidural anesthesia in elective operations, and pilot studies of fast track surgical procedures using the multimodality approach. Results: The introduction of newer approaches to perioperative care has reduced both morbidity and mortality in surgical patients. In the future, most elective operations will become day surgical procedures or require only 1 to 2 days of postoperative hospitalization. Reorganization of the perioperative team (anesthesiologists, surgeons, nurses, and physical therapists) will be essential to achieve successful fast track surgical programs. Conclusions: Understanding perioperative pathophysiology and implementation of care regimes to reduce the stress of an operation, will continue to accelerate rehabilitation associated with decreased hospitalization and increased satisfaction and safety after discharge. Developments and improvements of multimodal interventions within the context of "fast track" surgery programs represents the major challenge for the medical professionals working to achieve a "pain and risk free" perioperative course.

Multimodal strategies to improve surgical outcome.

Multimodal Approach to Control Postoperative Pathophysiology and Rehabilitation

### Philosophy of the guideline

### Assessing patients



Figure 1 Chart 1: Oxygen prescription for acutely hypoxaemic patients in hospital. ABG, arterial blood gas; COPD, chronic obstructive pulmonary disease; Fio2, fraction of inspired oxygen; ICU, intensive care unit; NIV, non-invasive ventilation; Pco2, carbon dioxide tension; Spo2, arterial oxygen saturation measured by pulse oximetry.

View this table:

Table 1 Critical illnesses requiring high levels of supplemental oxygen (see section 8.10)

### Oxygen prescription

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Table 2 Serious illnesses requiring moderate levels of supplemental oxygen if the patient is hypoxaemic (section 8.11)

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Table 3 COPD and other conditions requiring controlled or low-dose oxygen therapy (section 8.12)

### Oxygen administration



Figure 2 Chart 2: Flow chart for oxygen administration on general wards in hospitals. ABG, arterial blood gas; EPR, electronic patient record; EWS, Early Warning Score; Spo2, arterial oxygen saturation measured by pulse oximetry.

### Monitoring and maintenance of target saturation

https://thorax.bmj.com/content/thoraxjnl/63/Suppl_6/vi1.full.pdf

BTS guideline for emergency oxygen use in adult patients

Objective To identify and assess the impact of postoperative complications in patients with unrecognized or known obstructive sleep apnea syndrome (OSAS) undergoing hip replacement or knee replacement compared with control patients undergoing similar operations. Although OSAS is a risk factor for perioperative morbidity, data quantifying the magnitude of the problem in patients undergoing non-upper airway operations are limited. PATIENTS AND METHODS This retrospective, case-control study from a single academic medical institution included patients diagnosed as having OSAS between January 1995 and December 1998 and undergoing hip or knee replacement within 3 years before or anytime after their OSAS diagnosis. Patients with OSAS were subcategorized as having the diagnosis either before or after the surgery and also, regardless of time of diagnosis, by whether they were using continuous positive airway pressure (CPAP) prior to hospitalization. Matched controls were patients without OSAS undergoing the same operation. Interventions were defined specifically as administration of a particular treatment in the context of each complication, eg, supplemental oxygen, implementation of additional monitoring such as oximetry for hypoxemia, or transfer to the intensive care unit (ICU) for cardiac ischemia concerns. Postoperative complications were assessed for all patients in the different categories and included respiratory events such as hypoxemia, acute hypercapnia, and episodes of delirium. Serious complications were noted separately, including unplanned ICU days, reintubations, and cardiac events. The length of hospital stay was also tabulated. Results There were 101 patients with the diagnosis of OSAS in this study and 101 matched controls. Thirty-six patients had their joint replacement before OSAS was diagnosed, and 65 had surgery after OSAS was diagnosed. Of the latter 65 patients, only 33 were using CPAP at home preoperatively. Complications were noted in 39 patients (39%) in the OSAS group and 18 patients (18%) in the control group ( P =.001). Serious complications occurred in 24 patients (24%) in the OSAS group compared with 9 patients (9%) in the control group ( P =.004). Hospital stay was significantly longer for the OSAS patients at a mean ± SD of 6.8±2.8 days compared with 5.1±4.1 days for the control patients ( P Conclusion Adverse postoperative outcomes occurred at a higher rate in patients with a diagnosis of OSAS undergoing hip or knee replacement compared with a group of matched control patients.

https://www.mayoclinicproceedings.org/article/S0025-6196(11)62108-3/pdf

Postoperative complications in patients with obstructive sleep apnea syndrome undergoing hip or knee replacement: a case-control study

Major surgery is beset by complications such as pulmonary, cardiac, thromboembolic and cerebral dysfunction, which cannot be attributed solely to inadequate surgical and anaesthetic techniques, but rather to increased organ demands caused by the endocrine metabolic response to surgical trauma [33]. Postoperative cerebral dysfunction comprises delirium, confusion and milder degrees of mental dysfunction [1, 48, 53, 62], and disturbances in the normal sleep pattern [4, 7, 9, 13, 17, 34, 39, 42, 65]. Changes in early postoperative sleep [4, 7, 8, 13, 17, 34, 39, 42, 65] and sleep after non-surgical stress [10, 20, 24, 26, 27, 29, 60] are characterized by a decrease in total sleep time, elimination of rapid eye movement (REM) sleep, a marked reduction in the amount of slow wave sleep (SWS) and increased amounts of non-REM (N-REM) sleep stage 2. Recent data have suggested that postoperative sleep disturbances may be involved in the development of altered mental function [27], postoperative episodic hypoxaemia [38, 65] and haemodynamic instability [40]. The aim of this article, therefore, is to review the incidence and duration of postoperative sleep disturbances, and to evaluate possible mechanisms and potential implications for postoperative outcome.

Postoperative sleep disturbances: mechanisms and clinical implications.

The sleep pattern and oxygenation of 10 patients undergoing laparoscopic cholecystectomy were studied on the night before operation and the first night after operation. Operations were performed during general anaesthesia and postoperative analgesia was achieved without the administration of opioids. There were no significant changes in the total time awake or the number of arousals on the postoperative night compared with the night before operation. During the postoperative night, we found a decrease (P = 0.02) in slow wave sleep (SWS) with a corresponding increase in stage 2 sleep (P = 0.01). SWS was absent in four of the patients after operation, whereas in six patients it was within the normal range (5-20% of the night). The proportion of rapid eye movement (REM) sleep was not significantly changed after operation. There were no changes in arterial oxygen saturation on the postoperative compared with the preoperative night. Comparison of our results with previous studies on SWS and REM sleep disturbances after open laparotomy, suggests that the magnitude of surgery or administration of opioids, or both, may be important factors in the development of postoperative sleep disturbances.

Sleep after laparoscopic cholecystectomy

Post-operative sleep disturbance, with suppression of rapid eye movement sleep and slow wave sleep followed by a subsequent rebound, seems to be related to the magnitude of trauma and thereby to the surgical stress response. In this context, cortisol, autonomic stimulation, and certain cytokines may lead to abnormal sleep. Furthermore, the environment, pain and the administration of analgesics seem to be important factors in the precipitation of sleep abnormalities. Post-operative sleep disturbance may contribute to the development of episodic hypoxaemia, haemodynamic instability and altered mental status, all of which have an influence on post-operative morbidity and mortality. Prevention or reduction of the post-operative sleep disturbance may be achieved by minimizing surgical trauma, changing the conventional nursing procedures, avoiding opioids and treating pain with non-opioid analgesics, although none of these methods has been thoroughly studied. Post-operative sleep disturbance represents an important research field, since it may have a significant adverse impact on post-operative outcome.

Post-operative sleep disturbance: causes, factors and effects on outcome

Background. Episodic hypoxaemia, cardiac arrhythmias, and myocardial ischaemia may be related after major abdominal surgery. Methods. We studied 52 patients on the second and third nights after major abdominal operations, using continuous pulse oximetry and Holter ECG. We recorded the amount of time spent with oxygen saturation values less than 90, 85, and 80% during the night, and noted episodes of hypoxaemia, tachycardia, bradycardia, and ST-segment changes. Results. In 87 study nights there were 2403 (individual range 1–229) episodes of hypoxaemia, 3509 (individual range 1–234) episodes of tachycardia, and 265 (individual range 1–73) episodes of ST segment deviation. Of the 52 patients, 50 had episodes of hypoxaemia and tachycardia, and 19 patients had one or more episodes of ST segment deviation. For 38% of the episodes of ST deviation, there was an episode of hypoxaemia at the same time and in 16% there was an episode of tachycardia. ST deviation was only noted in 4% of the episodes of hypoxaemia and in 1% of the episodes of tachycardia. Conclusion. Episodes of hypoxaemia and tachycardia frequently occur together after surgery but are rarely associated with ST deviation. Hypoxaemia or tachycardia is often present at the same time as ST deviation occurs.

Relationship between nocturnal hypoxaemia, tachycardia and myocardial ischaemia after major abdominal surgery.

Background: Cardiac complications are common during the postoperative period and may be associated with hypoxemia and tachycardia. Preliminary studies in high-risk patients after operation have shown a possible beneficial effect of oxygen therapy on arterial oxygen saturation and heart rate. Methods: The authors studied the effect of oxygen therapy on arterial oxygen saturation and heart rate in 100 consecutive unselected patients randomly and double blindly allocated to receive air or oxygen therapy between the first and fourth day after major abdominal surgery. Results: The median arterial oxygen saturation rate increased significantly from 96% to 99% (P < 0.0001) and the heart rate decreased significantly from 85 beats/min to 81 beats/min (P < 0.0001) during oxygen supplementation compared with air administered by a binasal catheter. The greatest decrease in heart rate occurred in patients with the lowest oxygen saturation or the highest heart rate values before oxygen supplementation. Overall, 73% of this unselected group of patients responded with decreased heart rate during supplemental oxygen therapy. No significant differences in changes in heart rate after oxygen supplementation were found between patients with or without an epidural catheter or between the postoperative day studied. Conclusion: Postoperative oxygen therapy increased arterial oxygen saturation and decreased heart rate after uncomplicated abdominal surgery in a consecutive unselected group of patients who received routine postoperative care.

S. Rosenberg-Adamsen

Papers

Postoperative sleep disturbances: mechanisms and clinical implications.

Sleep after laparoscopic cholecystectomy

Post-operative sleep disturbance: causes, factors and effects on outcome

Relationship between nocturnal hypoxaemia, tachycardia and myocardial ischaemia after major abdominal surgery.

Effect of oxygen treatment on heart rate after abdominal surgery.