European Journal of Cardiovascular Medicine

Chronic Obstructive Pulmonary Disease (COPD) is currently among the leading three causes of death globally, with 90% of these fatalities occurring in low- and middle-income countries (LMICs).¹ In 2012, over 3 million individuals lost their lives due to COPD, which accounted for 6% of all deaths worldwide. COPD poses a significant public health issue that is both preventable and manageable. This disease is a primary contributor to long-term illness and mortality around the globe; many individuals endure this condition for extended periods and pass away prematurely as a result of it or its complications. The global burden of COPD is expected to rise in the coming years due to ongoing exposure to COPD risk factors and an ageing population.²

As a developing country, India faces a shortage of intensive healthcare resources and significant constraints on healthcare services. The enhancement of economic and healthcare systems has led to an increased life expectancy for the Indian population, resulting in a higher prevalence of age-related conditions such as COPD. There are significantly more COPD patients who might benefit from mechanical ventilation in cases of sudden respiratory failure than there are critical care units available to meet this need. Therefore, it is essential to develop strategies for categorising patients based on their need for mechanical ventilation or intubation.³

In light of the current circumstances, it is possible to quickly arrange and efficiently utilise these limited critical care resources if patients with COPD exacerbations who may require intubation and mechanical ventilation during their hospital admission are identified on the first day of their stay. One of the several grading systems used in ICUs is the APACHE II (Acute Physiology and Chronic Health Evaluation II), which evaluates conditions based on their severity. This system is applied within the first 24 hours of a patient’s admission and is based on two disease-related variables and 12 standard physiological assessments. A higher APACHE II score reflects a more severe form of the illness, with the score ranging from 0 to 71 points. Premorbid functional status serves as a morbidity indicator that highlights the level of independence in performing daily tasks and the severity of COPD and associated conditions. It also indicates the degree of dyspnea experienced by the individuals.

OBJECTIVES

1. To compare the duration of smoking in pack years first-day values of pH PaCO2 in predicting the need for mechanical ventilation in Acute Exacerbation of COPD.
2. To compare S. Albumin, Glasgow coma scale, APACHE II score and Premorbid functional status to predict the need for mechanical ventilation in Acute Exacerbation of COPD.

SStudy Design:

Prospective hospital-based observational study.

Study area:

 The study was conducted in the Department of Pulmonary Medicine, Katuri Medical College and Hospital, Guntur. 

Study Period: 

June 2022 to May 2023. (1 year).

Sample size:

The study consisted of 100 subjects.

Study population:

The present study was conducted on 100 cases, including males and females, from Pulmonology OPD, Katuri Medical College and Hospital, Guntur.

Sampling method:

Simple random Sampling Technique.

Inclusion criteria:

1. Patients who are admitted with the primary diagnosis of acute exacerbation of COPD.
2. All patients must possess a previously verified diagnosis of COPD based on a FEV1/FVC ratio of less than 0.70 and should be receiving consistent monitoring and treatment.
3. The diagnosis of exacerbation of COPD was made based on the deterioration of at least one of the following symptoms: dyspnea, cough, or sputum production.

Exclusion criteria:

1. The study excluded patients with underlying COPD who were admitted with another primary diagnosis, such as stroke or acute myocardial infarction.
2. The study excluded patients with acute respiratory failure caused by bronchiectasis, bronchial asthma, active or inactive TB, pneumothorax, pulmonary embolism, or pulmonary oedema.

Ethical consideration:

Institutional Ethical committee permission was taken before the commencement of the study.

Study tools and Data collection procedure:

A preexisting proforma was utilised to gather the demographic and clinical information of the patients. Each patient underwent a comprehensive clinical assessment and received relevant diagnostic tests. The demographic profile obtained through a questionnaire upon admission encompassed information regarding age, gender, and smoking habits. Patient vitals, including heart rate, blood pressure and breathing rate, were recorded. The patient's premorbid functional state for the last month was determined using the modified Menzies criteria or family members in case the patient was incapable of furnishing the information. Routine tests such as arterial blood gas analysis, liver function tests⁵, renal function tests, and serum electrolyte testing were performed for the patients. The APACHE II score was computed for each patient using the following data: age, temperature, mean arterial pressure, heart rate, respiratory rate, FiO2, arterial pH, serum HCO3, serum sodium, serum potassium, serum creatinine, packed cell volume, WBC count, and Glasgow Coma Scale. Patients were intubated rapidly in cases when non-invasive ventilation (NIV) was not suitable or ineffective. This was done if patients experienced extreme difficulty in breathing and increased effort in breathing, if they had acute respiratory acidosis with a pH level below 7.25 and a PaCO2 level above 60 mmHg, if their respiratory rate exceeded 35 breaths per minute, or if their PaO2 level dropped below 40 mmHg.

LABORATORY INVESTIGATIONS:

Haemoglobin

WBC count Blood Glucose

Bilirubin – Total, Direct, Indirect SGOT, SGPT Total Protein

Serum Albumin Blood Urea Serum Creatinine Serum Sodium Serum Potassium Serum Calcium

Arterial Blood Gas Analysis (arterial pH, Serum HCO3

SCORE CALCULATION:

Premorbid Functional Status (Modified Menzies Criteria)⁶ (for the last 1 month)

1. Independent - functioning or residing without assistance31
2. Restricted - permitted to leave the residence, but physical activity is limited.
3. Housebound - infrequently ventures outside the residence but is capable of performing personal care tasks.
4. Immobile - unable to perform self-care tasks while in bed or chair.⁷

Acute Physiology and Chronic Health Evaluation II (APACHE II) score

1. Age
2. Glasgow Coma Scale
3. Temperature
4. Heart rate
5. Respiratory rate
6. Mean arterial pressure
7. Packed cell volume
8. WBC Count
9. Arterial Ph
10. Serum Sodium
11. Serum Potassium
12. Serum Creatinine
13. A-a Gradient (if FiO2>0.5) or PaO2 (if FiO2 <0.5)
14. Chronic health problems {Cirrhosis/ NYHA –IV/Severe COPD/ Regular HD/ Immunocompromised}

TOTAL SCORE-

Statistical analysis:

The information collected regarding all the selected cases was recorded in a master chart. Data Analysis was done using the advanced Excel Data Analysis tool pak and IBM SPSS Statistics 29.0.1. version (2023) Open-source programming statistical software. Using this software, mean, standard deviation and “p” value were calculated through the One-way ANOVA Chi-square test, and a P value of < 0.05 was taken as significant.

Table 1: AGE DISTRIBUTION IN COPD

Of the 100 patients included in the study, 26 belonged to the age group (< 50 years) {26%}, whereas 74 patients {74%} were over 50 years of age. We already know COPD is a disease that affects elderly persons. The findings of this study are similar to our earlier knowledge.

Table 2: SEX DISTRIBUTION IN COPD

Of the total 100 COPD patients used in the study,

• Males were 76 (76%)
• Females were 24 (24%)

The prevalence of COPD, as we already know, is much higher in males than females, probably due to the higher prevalence of smoking in males. Our study also confirms the same.

As we already know, the major etiological factor in COPD is cigarette smoking. In our study, smokers comprised 75 (75%) of the total 100 cases.

Table 3: DURATION OF SMOKING v/s MECHANICAL VENTILATION

In our study

• 14 cases who had smoked for 1-10 pack years eventually required mechanical ventilation.
• 17 of the 40 cases with pack years 11-20 needed mechanical ventilation.
• 2 of the 4 with pack years 21-30 needed mechanical ventilation.
• 3 of the 4 cases with pack years >30 needed mechanical ventilation.
• P value was found to be <0.001, which shows that the association between the duration of smoking and the need for mechanical ventilation is significant. Hence, COPD patients with long duration of smoking as measured by pack years are more likely to require mechanical ventilation in case of acute exacerbations.

Table 4: pH VERSUS NEED FOR MECHANICAL VENTILATION

Of the total 100 COPD patients, 46 had a pH of <7.2, of whom 39 eventually needed mechanical ventilation, whereas only 11 of 54 patients with pH >7.2 eventually needed mechanical ventilation. The p-value of <0.001 obtained by our study indicates that pH <7.2 is an independent predictor for mechanical ventilation in COPD patients.

Table 5: GLASGOW COMA SCALE VERSUS NEED FOR MECHANICAL VENTILATION

Of the total 100 COPD patients, 39 had a GCS < 13, of whom 29 eventually needed mechanical ventilation, whereas only 20 of 61 patients with GCS >13 eventually needed mechanical ventilation. The p-value of <0.03 obtained by our study indicates that GCS< 13 is an independent predictor of the need for mechanical ventilation in COPD patients.

Table 6: APACHE II SCORE VERSUS NEED FOR MECHANICAL VENTILATION

Of the total 100 patients, 63 had an APACHE II score of < 15 on the day of admission, of which 18 eventually needed mechanical ventilation, whereas 3 7 patients had APACHE II score > 15 on the day of admission, of whom 31 needed mechanical ventilation. P value <0.001 obtained by our study indicates that an APACHE II score >15 on the day of admission is an independent predictor of the need for mechanical ventilation.

Table 7: SERUM ALBUMIN VERSUS NEED FOR MECHANICAL VENTILATION

Of the total 100 patients included in the study, 37 had serum albumin <3 g/dl on the day of admission, of whom 27 were eventually given mechanical ventilation, whereas 63 had serum albumin > 3 g/dl on the day of admission, of whom 23 eventually needed mechanical ventilation. P value < 0.001 indicates that serum albumin < 3 g/dl on the day of admission is an independent predictor of the need for mechanical ventilation.

Of the total 100 patients, 27 had a PaCO2 of < 60mm Hg, of which seven patients eventually were given mechanical ventilation.

Seventy-three patients had a PaCO2 >60 mmHg, of whom 43 later had to be given mechanical ventilation. P value was <0.001, which indicates that PaCO2 > 60 mmHg on the day of admission is a significant independent predictor of the need for mechanical ventilation.

Table 8: PREMORBID   FUNCTIONAL  SCORE VERSUS NEED FOR MECHANICAL VENTILATION

Of the total 100 patients, 25 were assigned to Grade I, with 6 of them needing mechanical ventilation; 28 were included in Grade II, with 11 needing mechanical ventilation; 23 were in Grade III, with 14 of them needing mechanical ventilation, and 24 were in Grade IV with 19 needing mechanical ventilation eventually. Hence, 17 of the 53 patients in Grade I and II and 33 of the 49 patients in Grade III and IV needed mechanical ventilation. A p-value of 0.005 is significant, indicating that the premorbid functional status of Grades III and IV is an independent predictor of the need for mechanical ventilation.

In our study, the majority (74%) of patients were over 50 years of age. We already know COPD is a disease that affects elderly persons. The findings of this study are similar to our earlier knowledge. In our study, the majority (76%) of patients were males. The prevalence of COPD, as we already know, is much higher in males than females, probably due to the higher prevalence of smoking. Our study also follows the same prevalence pattern.

In our study, smokers comprised 75 (75%) of the total 100 cases. As we already know, the major etiological factor in COPD is cigarette smoking. Hence, our finding was in line with previous studies. Madkour et al.⁸ have described the relationship between smoking duration, measured in pack-years, and the likelihood of requiring mechanical ventilation. The study findings indicate a substantial relationship between the duration of smoking and the requirement for mechanical ventilation, as evidenced by a P value of less than 0.001. Therefore, our results align with prior research, indicating that individuals with chronic obstructive pulmonary disease (COPD) who have smoked heavily for many years, as defined by pack years, are at a higher risk of needing mechanical ventilation during acute exacerbations. Arterial Blood pH on the day of admission has been earlier studied by other groups.

According to Khilnani et al.,^9, a pH level below 7.26 is considered significant in terms of necessity for mechanical ventilation. Hoo et al.¹⁰ have also determined that a pH level below 7.25 is noteworthy, with the highest intubation rate observed at a pH level below 7.20. Kumar et al. have discovered that a pH level below 7.20 is a noteworthy indicator. Our investigation revealed a parallel pattern, as 84.7 % of patients who had a pH level below 7.2 on the initial day ultimately required mechanical ventilation. Acidosis in severe acute exacerbations can be attributed to ventilation-perfusion mismatch, alveolar hypoventilation, and respiratory muscle exhaustion.

Ucgun et al.¹¹ have found Glasgow Coma Scale (GCS) scores below nine as a major indicator of the need for mechanical breathing. Our investigation has found that a Glasgow Coma Scale (GCS) score of less than 13 is statistically significant. The reason for the lower threshold in our study is likely attributed to the higher frequency of intubation and the relatively limited accessibility to noninvasive breathing.

Vitacca et al.¹² have identified an APACHE II score greater than 22 as a significant predictor of the requirement for mechanical ventilation. Ucgun et al.¹¹ determined that an APACHE II score greater than 23 was statistically significant. In coast, Kumar et al.¹³ identified an APACHE II score greater than 11.5 as an independent predictor of intubation. The pattern observed in our study closely resembled the latter, as 83.7% of patients with APACHE scores greater than 15 ultimately required mechanical breathing.

Khilnani et al.⁹ have previously identified that albumin levels below 3.5 g/dl are a significant predictor of the need for mechanical ventilation. On the coast, Vitacca et al.¹² colleagues observed no significant correlation between albumin and mechanical ventilation in their investigation. The study has confirmed the results of Khilnani et al.⁹ and suggests that having a blood albumin level of less than 3 g/dl is a strong indicator of the need for intubation. Specifically, 72.97% of patients with albumin levels below 3 g/dl on the first day required mechanical breathing. Serum Albumin serves as a reliable indicator of the nutritional condition of patients. Malnourished individuals with COPD have a higher likelihood of requiring intubation and mechanical breathing when experiencing an acute insult, such as an exacerbation. This elucidates the rationale behind the predictive capacity of low serum albumin.

According to Kumar et al.,^13, a PaCO2 level higher than 68 mm Hg is considered a strong indicator of the need for mechanical ventilation. Our study revealed that when the PaCO2 levels on the first day were above 60 mm Hg, a considerable proportion (58.9%) of patients required mechanical breathing during their hospitalisation. Severe acute exacerbations can lead to elevated PaCO2 due to ventilation-perfusion mismatch, alveolar hypoventilation, and respiratory muscle fatigue.

Premorbid functional status shows the severity of COPD as well as associated underlying comorbid conditions. Menzies et al. have shown that premorbid status is the most significant factor in predicting outcomes. Kumar et al. showed that worse premorbid status can predict the need for mechanical ventilation. In our study, 70.2% of patients with worse (Grade III and Grade IV) premorbid functional status according to modified Menzies score eventually required mechanical ventilation. Hence, the finding in our study parallels the previous studies.

Therefore, our research has determined that the length of smoking in pack years, initial values of arterial blood pH, PaCO2, Glasgow Coma Scale, APACHE II score, serum albumin, and premorbid functional status can serve as predictors for the requirement of mechanical ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD).

In conclusion, COPD predominantly affects males and individuals over 50, with smoking being the leading cause. Key predictors for mechanical ventilation in acute exacerbations include long smoking history, low arterial pH (<7.2), altered mental state (GCS <13), high APACHE II score (>15), low serum albumin (<3.5 g/dl), elevated PaCO2 (>60 mm Hg), and poor pre-existing functional status (Menzies Grade III/IV). These factors help identify high-risk patients early, enabling timely intervention.

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