Factors associated with immediate postoperative pulmonary complications after Appendectomies under general anesthesia: A retrospective analysis

Background: Postoperative pulmonary complications (PPC) include any complication that affects the respiratory system after anesthesia and surgery and are a significant cause of postoperative mortality and morbidity. Objectives: To describe the risk factors for immediate postoperative pulmonary complications after appendectomy under general anesthesia and to determine if rapid sequence induction decreases the risk. Design and Setting: A retrospective analysis of perioperative medical records of patients who underwent appendectomy under general anesthesia over a year, from January 1st, 2014, to December 31st, 2014, at Hamad General Hospital, Doha, Qatar, was done. Results: Of the 1005 patients who met the inclusion criteria, 27 (3.7%) had PPC. The incidence of PPC had a significant positive association with diabetes mellitus (DM), bronchial asthma (BA), number of intubation attempts, laparoscopic approach, and longer surgeries (>2 h). Hypertension, recent or ongoing upper respiratory tract infections, and smoking were not associated with an increased risk of PPC. Non-rapid sequence intubation (RSI) was not associated with an increased risk of PPC compared with RSI. Conclusions: The incidence of immediate PPC in ASA 1 and 2 appendectomy patients aged between 15 and 50 is significant. There is an increased risk among asthmatics, diabetics, and those with difficult airways. The RSI technique does not offer protection.


INTRODUCTION
Acute appendicitis is among the most common causes of emergency abdominal surgery. 1 Worldwide, the total pooled incidence of appendicitis or appendectomy is around 100-150 per 100,000 person-years. 2Recent studies suggest a rise in the prevalence of appendicitis in developing countries between the early teenage years and the late 40s. 2 A higher prevalence is seen in men than in women.The disease outcome is affected by its natural course and the risks and complications of treatment. 2Postoperative pulmonary complications (PPC) include almost any complication that affects the respiratory system after anesthesia and surgery.4][5] The most severe PPCs are atelectasis, pneumonia, respiratory failure, and underlying chronic lung disease exacerbations. 6A systematic review by the American College of Physicians demonstrated that 60% of studies used a combination of pneumonia and respiratory failure to define PPCs. 6Emergency procedures and abdominal surgeries have a higher risk of regurgitation and aspiration. 7There is a lower risk of PPC in patients undergoing emergency appendectomy (laparoscopic or open) with rapid sequence induction (RSI) compared to non-RSI patients. 8n 2015, a European joint task force published guidelines for the perioperative clinical outcome (EPCO), defining pneumonia, acute respiratory distress syndrome (ARDS), and pulmonary embolism (PE) as individual adverse events and considering respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis to be the parameters. 3,9The precise outcome measures concerning PPC and associated risk factors in appendectomy patients have yet to be extensively studied.The primary aim of this study was to assess Factors associated with immediate postoperative pulmonary complications after Appendectomies      Intraoperative complications and events in PACU are described in Table 5, and multivariate logistic regression analysis of risk factors for PPC is shown in Table 6.The results showed that the use of total intravenous anesthesia (TIVA) is associated with a significantly higher odds ratio (OR) of 13.07 (with a confidence interval of 1.24-138.18)for PPC compared to inhalational plus intravenous anesthesia.Inhalational anesthesia alone had a lower OR of 1.07 (with a confidence interval of 0.47-2.43)than inhalational plus intravenous anesthesia.However, the differences between inhalational anesthesia and inhalational plus intravenous anesthesia were not statistically significant.

Incidence of PPC
The incidence of PPC in our study was 3.7%.0][11][12][13] The cited data on the incidence of PPC encompasses various populations and surgical procedures, not specifically appendectomy patients.The wide range of reported PPC incidences in the literature suggests that factors such as patient population, surgery type, and individual characteristics contribute to the variability.Therefore, although the current study's PPC incidence falls within the reported range, it's crucial to recognize that the referenced data does not directly apply to the appendectomy population in this study.

Gender distribution
In our study, the male-to-female ratio was 4.9:1.This higher male proportion is because of the population distribution of Qatar, where the predominant population in the age group of 15-50 years are expatriate male workers. 14,15Previous studies have shown a higher incidence of PPC in men than women, 10-12, but we did not find a significant difference.

Contributing factors to PPC
Airway instrumentation, multiple attempts, and assisted intubation techniques contribute to PPC.Difficult intubations were a predisposing factor for aspiration when performed electively by Sun et al., 7 thereby increasing the risk of PPC (67% risk in patients with no other prior risk factors).Proper assessment and adequate preparedness in airway management can considerably reduce multiple attempts and the risk of PCC.

RSI v/s non-RSI techniques
Istvan et al. 8 found considerable evidence in favor of RSI for reducing PPC.However, other authors have reported variable findings. 16,17We didn't find any significant association between the induction Factors associated with immediate postoperative pulmonary complications after Appendectomies and degree of severity of pulmonary complications. 18iabetes mellitus was shown to reduce FEV1 and FVC values as per the British Women's Heart and Health Study (1999-2001), leading to worsened clinical outcomes in the postoperative period. 19Though not assessed as an independent risk factor, deterioration of renal function and delayed gastric emptying increase the PPC, 6,19 which is also seen in DM.Our study shows that even minor surgeries like an appendectomy predispose people with diabetes to a higher risk of PPC.

Association with pre-existing pulmonary diseases
1][22][23][24] The pre-existing pulmonary co-morbidities predispose these patients to an increased tendency for bronchospasm, atelectasis, and pulmonary infections in response to airway instrumentation.In our study, BA was associated with an increased risk of PPC, with an OR of 3.65 (95% CI: 0.81-16.4),even though extensive data link smoking, pre-existing COPD, and URTI to PPC, 11,12,[20][21][22] no statistically significant risk was seen in our study.The absence of a statistically significant association does not necessarily imply the absence of an association.The sample size, selection bias, and other study limitations might influence the findings.The study population (15 to 50 years old and post-appendectomy) and methodological design (retrospective data review) may not have captured the full spectrum of PPC risk factors.Lastly, unmeasured confounding variables may have influenced the study's results.Overall, while it may be surprising that there was no statistically significant risk of PPC associated with smoking, pre-existing COPD, or URTI in the study, it is essential to remember that the results of a single study cannot be generalized and used to draw definitive conclusions.Additional research and meta-analyses are required to validate the findings and evaluate the study's robustness.Regional anesthesia techniques are usually beneficial to pulmonary function in response to pain.The chest wall and diaphragmatic dysfunction in response to pain can cause reduced pulmonary function. 25pe and PPC incidence in our study (OR: 0.87

Anesthesia maintenance method
The choice of anesthesia maintenance method can be crucial in reducing the risk of immediate PPC in this patient population.Healthcare providers should carefully consider the potential implications of utilizing TIVA versus inhalational plus intravenous anesthesia, particularly in high-risk patients or those prone to pulmonary complications.It is important to note that further research and larger-scale studies are warranted to validate these results and provide more robust evidence for guiding anesthesia practices.Nonetheless, these findings shed light on an essential aspect of perioperative care and emphasize the need for individualized anesthesia approaches to optimize patient outcomes.

Association with DM
DM was associated with a 16.7% incidence of PPC compared to the general population, with an OR of 7.74 (95% CI: 1.61-37.2).In the study by Wang et al., 10 patients with DM posted for orthopedic and general surgery had a high incidence of PPC (36.6%) with a delay in extubation because of respiratory failure and respiratory muscle weakness.In a study on patients with DM undergoing coronary artery bypass surgery (CABG), Lauruschkat et al. 18 observed similar outcomes.They found a significant need for reintubation and a need for ventilation for more than one day in the postoperative period in people with diabetes compared with nondiabetic patients (1.8% vs. 4.6%) and (4.8% vs. 9.9%), respectively.The extent of blood sugar control also determines the risk

CONCLUSIONS
The study shows that the incidence of PPC in young appendectomy patients with ASA 1 and 2 physical statuses is significant.The risk increases in those with BA, DM, and difficult airways requiring multiple intubation attempts.The RSI technique of anesthesia induction does not offer protection, whereas laparoscopic approaches and longer surgeries add to the risk of PPC.

PATIENT CONSENT
A waiver of consent was obtained from the Institutional Review Board (IRB) as this was a retrospective analysis of patients' electronic medical records.

Association with regional anesthesia and laparoscopic technique
Our study did not find a significant association between the type of regional anesthesia blocks for postoperative pain control and the incidence of PPC (Table 6).Our study found a positive association between PPC and laparoscopic technique [OR 2.2 (95% CI: 0.88-5.6)].A previous study showed a lower risk of PPC in laparoscopic surgery than in open surgery. 26The difference could be because there are factors that favor and do not favor the development of PPC in laparoscopic surgeries.A smaller abdominal incision in laparoscopic surgery causes limited chest wall restriction, whereas there is an increased risk of pneumoperitoneum-associated diaphragmatic push-up and basal atelectasis.The favorable relationship between PPC and laparoscopic methods could be attributed to several variables.Creating a pneumoperitoneum, which is necessary for laparoscopic surgeries, is one of them.Numerous physiological changes brought on by the pneumoperitoneum, such as increased intraabdominal pressure and reduced lung compliance, can make breathing harder for patients.Respiratory distress and a higher risk of PPC can result from this.There may be more causes for the link between PPC and laparoscopic surgery.For instance, laparoscopic surgery frequently requires extended anesthesia and operating time, which can raise the risk of PPC.Moreover, elderly patients or those with pre-existing respiratory issues may be more likely to undergo laparoscopic surgery, which can increase the PPC risk.Atelectasis was noted to occur more frequently in laparoscopic surgery by Jaschinski et al. 27 We found a positive correlation between the surgery duration and PPC, supporting previous findings. 6,11,22,23A Fernandez-Bustamante et al. 13 2013 study established higher ASA physical status as a risk factor.Our study was restricted to ASA 1 and 2 status patients and was not designed to evaluate this effect.We did not find a significant difference between ASA 1 and 2.

LIMITATIONS
1. Old data: Using samples from almost ten years ago is a significant limitation, as clinical

Table 4 . Clinical and surgical characteristics of study patients (1,005 patients).
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Table 5 . Intraoperative complications and Events in PACU (1,005 patients).
N: number of patients, PACU: post-anesthesia care unit, *: abnormal response to succinylcholine, effect ended after 80 minutes, the patient stayed intubated till full recovery of neuromuscular function.p = 0.07].No significant association was found between other comorbidities and PPC.While analyzing the anesthesia procedure-related risk factors, the study found no significant association between the type of induction (RSI vs. non-RSI) and the incidence of PPC.There was a direct association between multiple intubation attempts (more than 2) and PPC, with an incidence of 9% [OR 3.76, 95% CI: 0.46-30.51,p = 0.004].Laparoscopic surgeries were associated with a higher incidence of PPC than open procedures [OR 2.22, 95% CI: 0.88-5.6,P = 0.0001].

Table 6 . Multivariate logistic regression analysis of risk factors for PPC.
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