PURPOSE: Positive end expiratory pressure (PEEP) is routinely used during mechanical ventilation to improve oxygenation. Increased intra-thoracic pressure due to PEEP, we hypothesize, might subsequently increase the intra-abdominal pressure (IAP). Even slight rise in IAP could be detrimental to a pre-existing borderline or raised IAP. Hence the aim was to evaluate the effect of increasing levels of PEEP on the magnitude and rate of rise in IAP.
METHODS: After obtaining approval from departmental ethical committee and consent from patients relative, thirty adult patients undergoing emergency laparotomy, requiring postoperative elective mechanical ventilation were studied. The patients in whom application of PEEP was contraindicated were not included in the study. All the patients were paralysed with vecuronium bromide and sedation and analgesia was obtained with propofol and fentanyl respectively. The variables IAP, Mean Arterial Blood Pressure (MABP), arterial oxygen saturation (SpO2), Static lung compliance (Cst) and Mean airway pressure (Map) were obtained at zero PEEP. The PEEP was subsequently increased to 2, 4, 6, 8 and 10 cm of H2O and the respective values of the variables were observed after 10 minutes in each level of PEEP. Results were analysed using Pearson’s correlation and Paired T-test.
RESULTS: The IAP gradually increased from 4.2 ± 1.4 to 8.2 ± 1.9 cm of H2O (48.8%) with the increase in PEEP from 0 to 10 cmH2O. The rise in IAP was statistically significant (p < 0.05) from 4 cmH2O PEEP onwards. PEEP showed a significant linear correlation (Pearson correlation coefficient, R = 0.751, R2 = 0.9547). The linear regression equation was Y (IAP) = 0.4429 x (PEEP) + 3.7857, (p < 0.05). The Map and Cst increased significantly (p < 0.05).
CONCLUSIONS: IAP increases with PEEP and the increase is statistically significant after 4 cm H2O PEEP. There is a linear and positive correlation between PEEP and IAP.
CLINICAL IMPLICATIONS: One should be couscious while applying PEEP above 4 cm H2O, especially in patients with pre-existing raised IAP
DISCLOSURE: The following authors have nothing to disclose: Syed Ahmed, Rahul Gupta, Abu Nadeem, Mohd. Islam, Shiwani Agarwal, Asif Siddiqui
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