Changes in Driving Pressure vs Oxygenation as Predictor of Mortality in Moderate to Severe Acute Respiratory Distress Syndrome Patients Receiving Prone Position Ventilation

Background

Prone position ventilation (PPV) causes improvement in oxygenation, nevertheless, mortality in severe acute respiratory distress syndrome (ARDS) remains high. The changes in the driving pressure (DP) and its role in predicting mortality in moderate to severe ARDS patients receiving PPV is unexplored.

Methods

A prospective observational study, conducted between September 2020 and February 2023 on moderate-severe ARDS patients requiring PPV. The values of DP and oxygenation (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen [PaO2/FiO2]) before, during, and after PPV were recorded. The aim was to compare the DP and oxygenation before, during and after PPV sessions among moderate- severe ARDS patients, and determine the best predictor of mortality.

Results

Total of 52 patients were included; 28-day mortality was 57%. Among the survivors, DP prior to PPV as compared to post-PPV session reduced significantly, from 16.36 ± 2.57 cmH2O to 13.91 ± 1.74 cmH2O (p-value < 0.001), whereas DP did not reduce in the non-survivors (19.43 ± 3.16 to 19.70 ± 3.15 cmH2O (p-value = 0.318)]. Significant improvement in PaO2/FiO2 before PPV to post-PPV among both the survivors [92.75 [67.5-117.75]) to [205.50 (116.25-244.50)], (p-value < 0.001) and also among the non-survivors [87.90 (67.75-100.75)] to [112 (88.00-146.50)], (p-value < 0.001) was noted. Logistic regression analysis showed DP after PPV session as best predictor of mortality (p-value = 0.044) and its AUROC to predict mortality was 0.939, cut-off ≥16 cmH2O, 90% sensitivity, 82% specificity. The Kaplan-Meier curve of DP after PPV ≥16 cmH2O and <16 cmH2O was significant (Log-rank Mantel-Cox p-value < 0.001).

Conclusion

Prone position ventilation-induced decrease in DP is prognostic marker of survival than the increase in PaO2/FiO2. There is a primacy of DP, rather than oxygenation, in predicting mortality in moderate-severe ARDS. Post-PPV session DP ≥16 cmH2O was an independent predictor of mortality.

How to cite this article

Todur P, Nileshwar A, Chaudhuri S, Shanbhag V, Cherisma C. Changes in Driving Pressure vs Oxygenation as Predictor of Mortality in Moderate to Severe Acute Respiratory Distress Syndrome Patients Receiving Prone Position Ventilation. Indian J Crit Care Med 2024;28(2):134-140.

Incidence, Outcomes, and Predictors of Subphenotypes of Acute Kidney Injury among Acute Respiratory Distress Syndrome Patients: A Prospective Observational Study

Background

Acute kidney injury (AKI) is a heterogeneous syndrome with subphenotypes. Acute kidney injury is one of the most common complications in acute respiratory distress syndrome (ARDS) patients, which influences mortality.

Material and methods

It was a single-center observational study on 266 ARDS patients on invasive mechanical ventilation (IMV) to determine the subphenotypes of AKI associated with ARDS. Subphenotyping was done based on the serum creatinine (SCr) trajectories from day 1 to day 5 of IMV into resolving (subphenotype 1) or non-resolving (subphenotype 2) AKI.

Results

Out of 266 ARDS patients, 222 patients were included for data analysis. 141 patients (63.51%) had AKI. The incidence of subphenotype 2 AKI among the ARDS cohort was 78/222 (35.13%). Subphenotype 2 AKI was significantly more among the non-survivors (87.7% vs 36.2 %, p < 0.001). Subphenotype 2 AKI was an independent predictor of mortality among ARDS patients (p < 0.001, adjusted odds ratio 8.978, 95% CI [2.790-28.89]. AKI subphenotype 1 had higher median day 1 SCr than subphenotype 2 but lower levels by day 3 and day 5 of IMV. The median time of survival was 8 days in AKI subphenotype 2 vs 45 days in AKI with subphenotype 1 [Log-Rank (Mantel-Cox) p < 0.001]. The novel DRONE score (Driving pressure, Oxygenation, and Nutritional Evaluation) ≥ 4 predicted subphenotype 2 AKI.

Conclusion

The incidence of subphenotype 2 (non-resolving) AKI among ARDS patients on IMV was about 35% (vs 20% subphenotype 1 AKI), and it was an independent predictor of mortality. The DRONE score ≥4 can predict the AKI subphenotype 2.

Highlights

The serum creatinine trajectory-based subphenotype of AKI (resolving vs non-resolving) determines survival in ARDS patients. Non-resolving AKI subphenotype 2 is an independent predictor of mortality in ARDS. The novel DRONE score (driving pressure, oxygenation, and nutritional evaluation) ≥ 4 within 48 hours of IMV predicted the AKI subphenotype 2 among ventilated ARDS patients.

How to cite this article

Todur P, Nileshwar A, Chaudhuri S, Srinivas T. Incidence, Outcomes, and Predictors of Subphenotypes of Acute Kidney Injury among Acute Respiratory Distress Syndrome Patients: A Prospective Observational Study. Indian J Crit Care Med 2023;27(10):724-731.

Development and Internal Validation of a Novel Prognostic Score to Predict Mortality in Acute Respiratory Distress Syndrome - Driving Pressure, Oxygenation and Nutritional Evaluation - "DRONE Score"

Introduction

There are few scores for mortality prediction in acute respiratory distress syndrome (ARDS) incorporating comprehensive ventilatory, acute physiological, organ dysfunction, oxygenation, and nutritional parameters. This study aims to determine the risk factors of ARDS mortality from the above-mentioned parameters at 48 h of invasive mechanical ventilation (IMV), which are feasible across most intensive care unit settings.

Methods

Prospective, observational, single-center study with 150 patients with ARDS defined by Berlin definition, receiving IMV with lung protective strategy.

Results

Our study had a mortality of 41.3% (62/150). We developed a 9-point novel prediction score, the driving pressure oxygenation and nutritional evaluation (DRONE) score comprising of driving pressure (DP), oxygenation accessed by the ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) ratio and nutritional evaluation using the modified nutrition risk in the critically ill (mNUTRIC) score. Each component of the DRONE score with the cutoff value to predict mortality was assigned a particular score (the lowest DP within 48 h in a patient being always ≥15 cmH2O a score of 2, the highest achievable PaO2/FiO2 <208 was assigned a score of 4 and the mNUTRIC score ≥4 was assigned a score of (3). We obtained the DRONE score ≥4, area under the curve 0.860 to predict mortality. Cox regression for the DRONE score >4 was highly associated with mortality (P < 0.001, hazard ratio 5.43, 95% confidence interval [2.94-10.047]). Internal validation was done by bootstrap analysis. The clinical utility of the DRONE score ≥4 was assessed by Kaplan-Meier curve which showed significance.

Conclusions

The DRONE score ≥4 could be a reliable predictor of mortality at 48 h in ARDS patients receiving IMV.

Comparison of landmark-guided and ultrasound-guided technique for superior laryngeal nerve block to aid fibreoptic intubation - An observational study

Background and Aims

Awake fibreoptic intubation (AFOI) is the gold standard in the management of the difficult airway. Several methods to achieve airway anesthesia to aid AFOI include superior laryngeal nerve block (SLNB). This study aimed to compare land-mark-guided and ultrasound-guided techniques for SLNB to aid AFOI.

Material and Methods

This was a prospective, observational study. Patients in both groups received 1 mg Midazolam and 50 μg of fentanyl for mild sedation before intubation, nasal passages were anaesthetized using lignocaine-coated nasopharyngeal airways, nebulization of 3 ml of 2% lignocaine, and intratracheal injection of 2 ml of 2% lignocaine given through cricothyroid membrane. Patients in Group L received SNLB, at the lateral end of the thyrohyoid membrane (2 ml of 1.5% lignocaine). Patients in Group U had their thyrohyoid membrane visualized using linear ultrasound probe (8 - 13 Hz) and the injection was placed just superficial to the membrane using out of plane method. The groups were compared with respect to quality of anesthesia (assessed on a 5-point scale), patient comfort during AFOI, time taken to intubation and Haemodynamics.

Results

A total of 25 patients were enrolled: 13 in Group L and 12 patients in Group U. The demographics were comparable. Quality of airway anesthesia, time taken to intubation, haemodynamics and patient comfort were comparable. All were intubated successfully and there were no complications.

Conclusion

USG-guided SLNB was comparable to landmark-based method with respect to quality of airway anesthesia and patient comfort. USG-guided block did not add any advantage over the landmark-based method.

Utility of the Modified Nutritional Risk in the Critically ill Score as an Outcome Predictor in All-Cause Acute Respiratory Distress Syndrome and Acute Febrile Illness-Induced Acute Respiratory Distress Syndrome

Introduction

Nutritional risk in the Critically Ill (NUTRIC) score is a predictor of adverse outcomes in the critically ill, and its utility in a specific population of critically ill has been recommended. We aimed to study the utility of modified NUTRIC (mNUTRIC) score as a mortality predictor in acute febrile illness (AFI)-induced acute respiratory distress syndrome (ARDS) and all-cause ARDS patients.

Methods

We recorded data from two prospective observational ARDS studies conducted at a single-center tertiary care hospital to evaluate the utility of the mNUTRIC score as an independent mortality predictor in all-cause ARDS and AFI-ARDS. A total of 216 all-cause ARDS patients were included, of which 73 were AFI-ARDS and 143 were non-AFI ARDS.

Results

Mortality of AFI-ARDS was 16/73 (21.9%) compared to 62/143 (43.35%) in non-AFI ARDS (P = 0.002). There were no significant differences in severity of ARDS in AFI-ARDS and non-AFI ARDS groups (P = 0.504). The mNUTRIC score was found to be an independent predictor of mortality in all-cause ARDS patients (n = 216) and AFI-ARDS patients (n = 73) after Cox regression multivariable analysis. In all-cause ARDS, the mNUTRIC score had an area under the curve (AUC) of 0.778, cutoff ≥4, 82.1% sensitivity, and 65.9% specificity as a predictor of mortality. In AFI-ARDS, the mNUTRIC score had an AUC of 0.769, cutoff ≥4, 81.3% sensitivity, 66.67% specificity, and P = 0.001 as a predictor of mortality.

Conclusion

The mNUTRIC score is an independent mortality predictor for all-cause ARDS and AFI-ARDS patients. AFI-ARDS has significantly lesser mortality than non-AFI ARDS.

Evaluation of a new laryngoscope blade (Manipal throat packing blade) for throat pack insertion

Background and aims:

Insertion of a throat pack using a Macintosh laryngoscope after placing an oral Ring, Adair and Elwyn (RAE) tube fixed to the lower lip in the midline invariably results in the lateral movement of the tongue or the tube requiring repositioning. The aim was to design a laryngoscope blade that would produce minimal movement of the endotracheal tube or the tongue during the insertion of throat pack and compare it with the Macintosh laryngoscope blade.

Material and Methods:

A laryngoscope blade similar to the Doughty’s blade of Boyle Davis mouth gag with a groove in the center of the blade was initially designed. This was made of polyvinyl chloride to enable 3-D printing. Specifications given were modified after trial and error including addition of a flange. A bench study was then done to compare the Macintosh blade with the Manipal blade with and without flange. Forty anesthesia postgraduates and staff familiar with airway management inserted throat pack with each blade in random order in a manikin already intubated with an oral RAE tube and their impressions were noted.

Results:

The RAE tube remained in the midline after throat packing in 97.5 and 95% with Manipal blade with and without flange as compared to 52.5% with Macintosh blade. Ease of use was affected by the lack of sturdiness of the new blades. The light was good. Most people found both blades better or the same as the Macintosh blade.

Conclusion:

The Manipal laryngoscope blade with and without flange are both associated with the minimal lateral movement of the endotracheal tube and are easy to use. Their sturdiness must be improved.

Evaluation of the electronic stethoscope (FONODOC) as a cardiac screening tool during the preoperative evaluation of children

Background and Aims:

An electronic stethoscope with an inbuilt phonocardiogram is a potentially useful tool for paediatric cardiac evaluation in a resource-limited setting. We aimed to compare the acoustic and electronic stethoscopes with respect to the detection of murmurs as compared to the transthoracic echocardiogram (TTE).

Methods:

This was an observational study. Fifty children aged 0–12 years with congenital heart diseases (CHDs) and 50 without CHD scheduled for echocardiography were examined using both stethoscopes. The findings were corroborated with clinical findings and compared with the echocardiography report.

Results:

Among the 50 cases without CHD, no murmur was detected using either of the stethoscopes. This was in agreement with TTE findings. The calculated specificity of both stethoscopes was 100%. Amongst the 50 cases with CHD, the electronic stethoscope picked up murmurs in 32 cases and missed 18 cases. The acoustic stethoscope picked up murmurs in 29 cases and missed 21 cases. Thus, the sensitivity of electronic and acoustic stethoscopes as compared to TTE was calculated to be 64% and 58%, respectively. The positive predictive value of the electronic stethoscope as compared to TTE was 100% while the negative predictive value was 73%. The kappa statistic was 0.93 suggesting agreement in 93%. Mc-Nemar’s test value was 0.24 suggesting that the electronic stethoscope did not offer any advantage over the acoustic stethoscope for the detection of CHD in children.

Conclusion:

A comparison of the electronic stethoscope with an acoustic stethoscope suggests that the rate of detection of CHD with both stethoscopes is similar and echocardiography remains the gold standard.

Changes in stroke volume variation and cardiac index during open major bowel surgery

Background

Stroke volume variation (SVV) is a dynamic indicator of preload, which is a determinant of cardiac output. Aims: Aim of this study was to evaluate the relationship between changes in SVV and cardiac index (CI) in patients with normal left ventricular function undergoing major open abdominal surgery.

Patients and Methods

Patients undergoing major open abdominal surgery were monitored continuously with FloTrac® to measure SVV and CI along with standard monitoring. Both SVV and CI were noted at baseline and every 10 min thereafter till the end of surgery and were observed for concurrence between the measurements.

Results

1800 pairs of measurement of SVV and CI were obtained from 60 patients. Mean SVV and CI (of all patients) measured at different time points of measurement showed that as SVV increased with time, the CI dropped correspondingly. When individual readings of CI and SVV were plotted against each other, the scatter was found to be wide, reiterating the lack of agreement between the two parameters (R² = 0.035). SVV >13% suggesting hypovolemia was found at 207 time points. Of these, 175 had a CI >2.5 L/min/m² and only 32 patients had a CI <2.5 L/min/m².

Conclusion

SVV, a dynamic index of fluid responsiveness can be used to monitor patients expected to have large fluid shifts during major abdominal surgery. It is very specific and has a high negative predictive value. When SVV increases, CI is usually maintained. Since many factors affect SVV and CI, any increase in SVV >13%, must be correlated with other parameters before administration of the fluid challenge.

Distal tracheal resection and reconstruction through right posterolateral thoracotomy

Many retrospective series have been reported on the outcomes of tracheal resection for adenoid cystic carcinoma. However, demonstration on techniques of surgery and ventilatory management during the procedure are rare. We, herewith demonstrate a surgical video, wherein a distal tracheal resection was performed through right posterolateral thoracotomy.

Prospective evaluation of the utility of CHA2DS2-VASc score in the prediction of postoperative atrial fibrillation after off-pump coronary artery bypass surgery - An observational study

Introduction:

Off-pump coronary artery bypass (OPCAB) surgery is associated with evasion of complications of cardiac bypass. The incidence of postoperative atrial fibrillation (POAF) may also be reduced because of less ischemia and inflammation.

Aim:

Prospective evaluation of utility of CHA₂DS₂-VASc score in the prediction of POAF after OPCAB surgery.

Methodology:

In this prospective, observational study, 99 patients who underwent elective isolated OPCAB surgery were included. Patients with pacemaker in situ, receiving antiarrhythmic drugs preoperatively, and preexisting atrial fibrillation were excluded. A detailed history taking and physical examination were done preoperatively and the CHA₂DS₂-VASc scores were calculated for each patient. They received a standard anesthetic including midazolam, fentanyl, propofol, vecuronium, and isoflurane. The number of grafts, inotrope usage, and blood product transfusion in the perioperative period were noted. Patients were followed up for 5 days after surgery for development of new onset POAF requiring treatment.

Results:

About 20 of the 99 patients developed POAF. POAF occurred most commonly on postoperative day 2. They were older, more likely diabetic, had preoperative diastolic dysfunction, and received blood products perioperatively. POAF group had higher mean CHA₂DS₂-VASc score (3.6 ± 0.821 vs. 2.11 ± 1.35) and had longer hospital stay (16.85 ± 8.61 vs. 12.6 ± 4.05 days) than no POAF group. The cutoff for CHA₂DS₂-VASc score was 3, which showed 90% sensitivity, 77.22% specificity, 50% positive predictive value, and 96.63% negative predictive value.

Conclusions:

CHA₂DS₂-VASc score is useful in predicting POAF after OPCAB surgery. Higher the CHA₂DS₂-VASc score, greater is the possibility of development of POAF.

Preoperative laboratory testing - Comparison of National Institute of Clinical Excellence guidelines with current practice - An observational study

Background and Aims:

Preoperative laboratory testing is done to detect abnormalities in the body not detected by clinical examination. Often a battery of tests is advocated as a routine for patients scheduled for low or intermediate risk surgery. This prospective observational study was aimed to assess agreement of the current practice of preoperative laboratory investigations with the National Institute of Clinical Excellence (NICE) guidelines, and the impact of investigations on patient care and costs.

Material and Methods:

The study was conducted at a tertiary referral center on 385 patients aged 18-70 years of either gender, posted for elective general surgical, gynaecological or otolaryngological surgery. Sixteen investigations were examined: hemogram, blood urea, serum creatinine, serum electrolytes, coagulation profile, urinalysis, thyroid function tests, electrocardiogram, echocardiogram, chest x-ray, pulmonary function tests, blood sugar, glycosylated hemoglobin, liver function tests, treadmill test and coronary angiogram. The history and physical examination were reviewed to examine for indication for these laboratory investigations. These were compared with NICE guidelines. Impact of these investigations on anesthetic decision-making was noted.

Results:

There was almost no agreement of the current practice with the NICE guidelines. The total cost of all tests obtained was Rs 5,48,755. Total additional cost of unindicated tests was Rs 5,10,730 (93%). Average amount spent on additional investigations per patient was Rs 1326.57.

Conclusion:

Most investigations are overprescribed and have minimal agreement with NICE guidelines. None of the tests had any impact on clinical care. Nearly a million rupees is incurred per year in one referral hospital alone, when NICE guidelines are not followed.

Iatrogenic tracheobronchial tear during paediatric thoracoscopic oesophageal repair: an anaesthetic challenge

Iatrogenic tracheobronchial injury is rare. Limited data is available on such injuries in infants and management of these is challenging. We present a 7-month-old male infant who was diagnosed with oesophageal stricture, and was planned for thoracoscopic repair of the same. Anaesthetic management with a single lumen tracheal tube ensued. However, an intraoperative loss of capnogram and desaturation led to the diagnosis of iatrogenic tracheobronchial injury. After unsuccessful pursuits with a Fogarty catheter through the tracheobronchial tear and through the right bronchus for lung isolation, blind left endobronchial intubation with a smaller tube and one lung ventilation was successful. The rent was repaired by an open procedure, and oesophageal surgery completed. However, the child succumbed and died of multiorgan failure 3 days later.

Comparison of Bullard laryngoscope and short-handled Macintosh laryngoscope for orotracheal intubation in pediatric patients with simulated restriction of cervical spine movements

AIM

To compare time to intubation, time to optimal laryngoscopy, best laryngeal view, and success rate of intubation with pediatric Bullard laryngoscope and short-handled Macintosh laryngoscope in children being intubated with neck stabilization.

BACKGROUND

Securing airway of a patient with restricted cervical spine movement has been a challenge faced by anaesthesiologists around the world. Macintosh laryngoscope with manual inline stabilization is most commonly used. Bullard laryngoscope is also useful in this situation as minimal neck movement occurs with its use.

METHODS

Forty patients, ASA I or II, aged 2-10 years, were enrolled in this prospective, controlled, and randomized study. Patients were randomly allocated to one of two groups: Group MB (first laryngoscopy using short-handled Macintosh laryngoscope followed by pediatric Bullard laryngoscope) and Group BM (first laryngoscopy using pediatric Bullard laryngoscope followed by short-handled Macintosh laryngoscope) with manual inline stabilization after induction of anesthesia and paralysis. Trachea was intubated orally using the second equipment.

RESULTS

Laryngeal view when obtained was always Grade 1 with Bullard laryngoscope (38/38) when compared to Macintosh laryngoscope [Grade 1 (10/40)]. The mean time to laryngoscopy (and intubation) was shorter with Macintosh laryngoscope [15.53 s (38.15 s)] than Bullard laryngoscope [35.21 s (75.71 s)], respectively. Success rate of intubation was higher with Macintosh laryngoscope (100%) when compared to Bullard laryngoscope (70%).

CONCLUSIONS

Laryngoscopy and intubation is faster using a short-handled Macintosh laryngoscope with a higher success rate compared to pediatric Bullard laryngoscope in pediatric patients when manual inline stabilization is applied.

Comparison of intubating laryngeal mask airway and Bullard laryngoscope for oro-tracheal intubation in adult patients with simulated limitation of cervical movements

BACKGROUND

Intubation of a patient with limited cervical spine movement or in whom movement of the cervical spine is not desirable is always a challenge even to the most experienced anaesthesiologist. The intubating laryngeal mask airway (ILMA) and the Bullard laryngoscope (BL) are two instruments recommended for endotracheal intubation of such patients. We compared their utility and safety in patients with simulated cervical spine immobility using manual inline stabilization (MILS).

METHODS

Sixty-two patients, ASA I or II, between 18 and 65 yr, were enrolled in this prospective and randomized study. They were randomly allocated to one of the two groups: Group BL (Bullard laryngoscope) and Group IL (Intubating Laryngeal Mask Airway). The patients were intubated orally using either equipment after induction of general anaesthesia.

RESULTS

The success rate for intubation in the first or second attempt was higher in Group BL [90.32% (28/31)] than in Group IL [74.2% (23/31)] but was not statistically significant. The number of attempts taken for intubation and the total time to intubate were similar between the groups. Trauma as evidenced by blood on endotracheal tube or sore throat was similar in both groups.

CONCLUSIONS

Both the BL and the ILMA are useful equipment in intubating patients with limitation of cervical movements. Although not statistically significant, the BL may provide a higher success rate of intubation when compared with the ILMA.