Introduction

The postoperative pulmonary complication (PPC) includes almost any complication affecting the respiratory system after anaesthesia and surgery. The complications are defined heterogeneously in literature, occur commonly, have major adverse effects on patients and are difficult to predict. ¹ There are various definitions available in literature:

Ø  Respiratory complications that occur within 48-72 hours following surgery ²

Ø  Conditions affecting the respiratory tract that can adversely influence the clinical course of the patient after surgery ³

Ø  Any pulmonary abnormality occurring in the postoperative period that produces identifiable disease or dysfunction that is clinically significant and adversely affects the clinical course.

            The incidence of PPC varies widely from 5 to 40 %. This is mainly due to lack of uniformity about the inclusion of medical conditions as PPC, the population studied, the postoperative time frame studied, the type of postoperative care provided and outcome measures utilized. Some of the conditions included are atelectasis, pneumonia, bronchospasm, exacerbation of previous lung disease, pulmonary collapse due to mucus plugging of airways. Respiratory failure with ventilatory support > 48 hrs, acute lung injury (ALI) including aspiration pneumonitis, Transfusion related acute lung injury (TRALI), and acute respiratory distress syndrome (ARDS) and pulmonary embolism.⁴ The factors affecting the development of PPC are related to prior health status of patient and effects of anaesthesia and surgical trauma. The interaction between these factors determines risk. Usually risk factors are related to the surgical procedure, anaesthesia technique including perioperative analgesia and patient related including preoperative comorbidities. ⁵ Inadequate pain control in postoperative period may lead to increased risk of Postoperative pulmonary complications.

            The risk factors include patient related like advanced age, body mass index (BMI) , American Society of Anesthesiologist (ASA) physical status, comorbidities especially cardiac and pulmonary diseases , impaired liver and renal profile , low hemoglobin , preoperative drug use like steroids and history of smoking. The intraoperative factors include site of surgery (upper abdominal and thoracic have higher incidence of PPC ), duration of surgery, type of surgery emergency or elective, re-operation , intraoperative blood loss, amount of fluids given , intraoperative and postoperative analgesia. The incidence of PPC can be reduced by risk reduction strategies, performing short duration or minimally invasive surgery and use of anaesthetic technique of combined regional with general anaesthesia. Atelectasis is the main cause of PPCs. Atelectasis can be prevented or treated by adequate analgesia, incentive spirometry, deep breathing exercises, continuous positive airway pressure, mobilization of secretions and early ambulation^{. 4}

            This observational prospective study was designed to see the incidence and risk factors for PPC in major oncological surgeries in tertiary care institute. With this background the present study will be done to observe the incidence of PPC and associated risk factors in major oncological surgeries.

Aims and Objectives

1    To determine the incidence of postoperative pulmonary complications in major oncological surgeries.

2   To predict the relation between occurrence of postoperative pulmonary complications and associated risk factors.

Material and Methods

Study design: This observational prospective study will be conducted in Department of Onco-Anaesthesia and Palliative Medicine , DRBRAIRCH, AIIMS , New Delhi after approval from institutional ethical committee.

Methods:

            All the patients undergoing major elective or emergency oncological surgeries including head and neck surgeries, laparotomy, thoracotomy, joint dislocation and amputations under general or regional anaesthesia will be recruited in the study. Patients will be explained about the study protocol and written informed consent will be taken to participate in the study.

            The patient related information will be recorded on a standard performa. Patients demographic profile including weight, body mass index (BMI), comorbidities (including pulmonary and cardiac conditions), ASA physical status, functional capacity, history of smoking, history of previous chemotherapy/radiotherapy and any drug history would be recorded. Patient’s investigations including complete blood count, liver function test, renal function test, chest x-ray, electrocardiogram, and Echocardiograph / pulmonary function test (PFT) if done would be recorded from patients hospital record. These tests are routine preoperative tests and are recorded in patient’s hospital records.

            Anaesthesia and perioperative care will be provided as per standard by the concerned anaesthesiologist. Intraoperative details like type and duration of surgery, type of anaesthesia and analgesia especially use of regional blocks, airway management techniques, use of nasogastric tube, intraoperative blood loss, volume of fluid and blood replacement and any intraoperative complications (respiratory, cardiac etc) would be recorded.

The patients would be followed for postoperative pulmonary complications at Day 0, Day 1, Day 2, Day 5 and or at the time of discharge. The patients will also be followed for postoperative analgesia by NRS (Numeric Rating Scale) on a scale of 0 – 10 on these days. The minimum and maximum NRS over 24 hrs would be recorded.  The patients would be assessed for below mentioned PPC based on clinical or radiological findings as per the routine care. The radiological findings will be assessed in the background of clinical assessment and any discrepancy with regards to radiological findings will be ascertained by radiologists. The data will also be collected from clinical follow up, nursing charts, and electronic record of the patients for the rest of the days. The postoperative management of patients would be done according to the discretion of the anaesthesiologist, surgical oncologists and intensivist. Pulmonary complications would be defined according to standard definitions. Pulmonary complications include:

Ø  Pneumonia / Respiratory infection: Two or more of the following for > 48 hrs: new cough / sputum production, physical findings compatible with pneumonia, fever > 38º C , and new infiltrate on chest x-ray . ¹⁴

Ø  Respiratory Failure: Need for postoperative mechanical ventilation>48 hrs . Unplanned re-intubation because of respiratory distress, hypoxia, hypercarbia, or respiratory acidosis within 30 days of surgery or requiring NIV. ¹⁵

Ø  Bronchospasm : Newly detected expiratory wheeze treated with bronchodilators.¹⁶

Ø  Respiratory insufficiency: Postoperative hypoxemia (SpO₂ < 95 ) on room air and respiratory insufficiency requiring prolonged oxygen administration by nasal canula or face mask for > 1 day after surgery ⁶

Ø  Atelectasis: Radiological evidence on chest x-ray of collapse of lung segment which may be mild collapse to severe leading to lung opacification with mediastinal shift , hilum or hemidiaphragm shift towards effected area , with compensatory hyperinflation in adjacent nonatelectatic lung .¹⁶

Ø  ARDS : According to Berlin definition of ARDS ¹⁷

·         Timing  : Within 1 week of a known clinical insult or new or worsening respiratory symptoms

·         Chest imaging: Bilateral opacities — not fully explained by effusions, lobar/lung collapse, or nodules

·         Origin of edema  : Respiratory failure not fully explained by cardiac failure or fluid overload.Need objective assessment (e.g., echocardiography) to exclude hydrostatic edema if no risk factor present.

·         Oxygenation:

·         Mild 200 mmHg < PaO2/FIO2 ≤300 mmHg with PEEP or CPAP ≥5 cmH2Oc

·         Moderate100 mmHg < PaO2/FIO2 ≤200 mmHg with PEEP ≥5 cmH2O

·         SeverePaO2/FIO2 ≤100 mmHg with PEEP ≥5 cmH2O

Ø  TRALI : TRALI has been defined by both National Heart , Lung and Blood Institute (NHLBI ) working group as well as Canadian Consensus Conference , as new acute lung injury( ALI )/ Acute respiratory distress syndrome occurring during or within six hours after blood product administration . When a clear temporal relationship to an alternative risk factor for ALI/ ARDS coexists, a formal diagnosis of TRALI cannot be made^{. 18}

Ø  Pneumothorax: Any amount of air in the pleural space with no vascular bed surrounding the visceral pleura as confirmed on chest x-ray. Pneumothorax requiring thoracocentesis or ICD.¹⁹

Ø  Pleural effusion : Chest X Ray with blunting of costophrenic angle, loss of sharp silhouette of the ipsilateral diaphragm in upright position , displacement of anatomical structures ²⁰

Ø  Pulmonary embolism : Symptoms and signs suggestive of pulmonary embolism such as dyspnea, chest pain , tachycardia, tachypnea leading to suspected diagnosis of pulmonary embolism by Wells criteria ²¹

·         Symptoms of DVT (3 points)

·         No alternative diagnosis better explains the illness (3 points)

·         Tachycardia with pulse > 100 (1.5 points)

·         Immobilization (>= 3 days) or surgery in the previous four weeks (1.5 points)

·         Prior history of DVT or pulmonary embolism (1.5 points)

·         Presence of hemoptysis (1 point)

·         Presence of malignancy ( 1 point )

o   Score > 4 PE likely

o   Score < 4 PE unlikely 

Ø  Pulmonary edema: Symptoms and signs suggestive of fluid overload or congestive heart failure such as dyspnea , orthopnea , PND , hemoptysis , raised JVP , peripheral edema, B/L crepitations and presence of third heart sound. ²²

Ø  Bronchopleural Fistula: Can be diagnosed clinically and radiologically. Clinical features include fever with serosanguinous or purulent sputum . The diagnosis must be suspected when there is a persistent postoperative air leak (immediate postoperative period) or when there is a new or increasing air fluid level . Radiological features suggestive of presence or the development of a BPF include (1) steady increase in intrapleural air space (2 ) appearance of a new air fluid level (3 ) changes in an already present air fluid level (4) development of tension pneumothorax . The diagnosis may be further confimed by fibreoptic bronchoscopy ²³

            Any mortality during the study period will also be recorded. The possible reason based on clinical assessment or with available investigation and imaging will be assessed and recorded.

Statistical Analysis:

Sample size:

            After extensive review literature search, we found incidence of PPC in the range of 5% to 40%. Considering 40% incidence with 5% allowable error, the required sample size of our study is 385.

            To describe patients characteristics like demographic parameters , the data will be summarized and analysed using STATA (version 14) software. Data will be expressed as mean +/- SD or number and percentage as appropriate for qualitative and quantitative variables. Data will be tested for normality using the Kolmogorov – Smirnov test .T Test will be used to compare the parametric values, whereas the Mann – Whitney U test will be performed to compare the nonparametric values . For comparision of categorial  data  , the chi- square test / Fischer exact test will be used. Multiple regression analysis will be performed with use of logistic regression. A stepwise approach will be used to estimate the risk and relative 95 % confidence interval for each covariate. A value of p less than 0.05 will be considered to represent statistical significance of the study.