alveolar units in preparation for abdominal wall closure and an increase in intra‐abdominal pressure. A square waveform is associated with decreased recruitment by comparison. Since there are no valves between the brain and the right atrium, cerebral venous drainage is enhanced with more time at a lower intra‐thoracic pressure – a direct consequence of a shorter inspiratory and a longer expiratory time, both of which are characteristic of the square waveform gas delivery profile. Those with clinically severe obesity demonstrate increased intra‐abdominal pressure at baseline and therefore benefit from the use of a decelerating waveform to help reduce peak airway pressure and support postero‐basal pulmonary recruitment as well.Answer: AHamahata NT, Sato R and Daoud EG Go with the flow‐clinical importance of flow curves during mechanical ventilation: a narrative review. Can J Respir Ther. 2020; 56: 11–20 doi: 10.29390/cjrt‐2020‐002. PMID: 32844110; PMCID: PMC7427988.17 A surgical ICU’s data indicates that the mean length of time spent on mechanical ventilation is longer than desired. Which of the following is most likely to reduce the duration of mechanical ventilation for their patient population?Emplacing a night‐time intensivistUsing the ICU liberation bundleDaily bedside physical therapyEliminating benzodiazepine useEliminating opioid analgesic useThe goal of reducing the time spent on mechanical ventilation is a worthy goal for every ICU. This benefits from a multi‐professional approach to care that empowers team members to work together across every shift to facilitate liberation from mechanical ventilation. Reduced time to liberation as well as increased ventilator free days are not associated with a night‐time intensivist, physical therapy, nor eliminating a specific class of therapeutics. Both of those parameters are tightly tied to the A through F ICU liberation bundle that reduces ICU length of stay, duration of mechanical ventilation, delirium and coma, while engaging and empowering family members to participate in care and care planning. An important consequence of using the bundle is that patients often report more pain as sedating agents – including analgesics – are reduced to engage them in their own plan of care. This occurrence supports a multi‐modal non‐opioid approach to analgesia that helps address the opioid crisis as well. While it is unrealistic to eliminate opioid analgesic use, especially in the post‐operative or post‐injury patient, the use of opioids as the sole agent for sedation may be entirely abandoned in favor of other agents that target sedation as needed.Answer: BPun BT, Balas MC, Barnes‐Daly MA, et al. Caring for critically ill patients with the ABCDEF bundle: results of the ICU liberation collaborative in over 15,000 adults. Critical Care Medicine. 2019; 47(1): 3. doi: 10.1097/CCM.0000000000003482.
18 The use of flexible bronchoscopy and bronchoalveolar lavage for the invasive diagnosis of pneumonia in the critically ill is associated with which of the following benefits?Reduced FIO2 requirementImproved cardiac outputIncreased anti‐fungal agent useReduced antibiotic durationIncreased multi‐drug resistanceFlexible bronchoscopy and bronchoalveolar lavage (BAL) to invasively identify pneumonia confers the anticipated benefit of having confidence in the diagnosis of “no pneumonia”. The lack of an infecting organism supports termination of empiric antibiotic therapy, reduced driving pressure for resistant organism genesis, and enhances an institutional approach to antibiotic stewardship. This in turn helps drive investigations into alternate explanations for the clinical findings and presentation. Flexible bronchoscopy for relief of lobar collapse from airway obstruction (but not BAL) is associated with reduced FIO2 and improved cardiac output. Anti‐fungal use is not increased by BAL, as those with risk factors for fungal pneumonia – and who have a compatible presentation – are generally empirically treated for fungal pathogens; guidelines to direct anti‐fungal use have been articulated by a variety of organizations including the Infectious Disease Society of America.Answer: DRanzani OT, Senussi T, Idone F, et al. Invasive and non‐invasive diagnostic approaches for microbiological diagnosis of hospital‐acquired pneumonia. Critical Care. 2019; 23(1): 51. https://doi.org/10.1186/s13054‐019‐2348‐2
19 A 38‐year‐old patient with chest and abdominal blunt injury after a MVC has progressive ARDS and is managed using epinephrine and vasopressin infusions as well as glucocorticoid therapy for critical illness‐related cortico‐adrenal insufficiency. He has ongoing hypoxemic acute respiratory failure. Which of the following best supports pursuing cannulation for veno‐venous extracorporeal membrane oxygenation (VV‐ECMO)?PaO2/FIO2 ratio of 135 on a FIO2 of 0.7Stabilized thoracic spine fracturesInability to undergo prone position therapyIncreasing epinephrine dose for MAP supportEjection fraction of 30%VV‐ECMO provides oxygenation support and clears CO2. It does not support cardiac performance. Therefore, an increasing need for vasopressor infusion or depressed ejection fraction does not drive one towards VV‐ECMO but would instead favor veno‐arterial ECMO. A PaO2/FIO2 ratio of 135 on an FIO2 of 0.7 indicates additional opportunity for oxygenation management such that ECMO is not required. Stabilized spine fractures should not generally influence the decision for VV ECMO. However, the inability to pursue standard care such as prone position therapy supports pursuing cannulation as rescue therapy, particularly in those with an escalating O2 requirement or the progressive inability to clear CO2.Answer: CMenk M, Estenssoro E, Sahetya SK, et al. Current and evolving standards of care for patients with ARDS. Intensive Care Med. 2020; 46:2157–2167. https://doi.org/10.1007/s00134‐020‐06299‐6
20 A patient with COPD has undergone an uneventful right hepatectomy for malignancy and arrives to the SICU intubated and mechanically ventilated. Settings are AC RR 12 breaths/minute, tidal volume 650 mL, FIO2 50%, PEEP 5, decelerating waveform, peak flow rate = 60 LPM; Pawpeak = 32; Pawmean = 8; SpO2 = 96%; ETCO2 = 42 torr and he is breathing with the ventilator. VS: T = 100.2°F, HR = 84 beats/minute, and BP = 132/74 mm Hg. One hour later, you are called for HR = 132 beats/minute, BP = 82/46, T = 98.9°F, SpO2 = 84%, ETCO2 = 58; RR = 20 breaths/minute. The most appropriate initial intervention is which of the following?Return to the OR for hemorrhage controlStart a continuous epinephrine infusionTherapeutic cardioversion for atrial fibrillationDisconnect the patient from the ventilatorEmergency pleural decompression Patients with COPD often undergo surgery for unrelated conditions such as the patient in this question. Given that COPD eases gas entry but renders gas exit more difficult, such patients are at increased risk of gas trapping and increased intra‐thoracic pressure. This is a particular risk on volume cycled ventilation when the patient’s respiratory rate increases (anesthesia emergence, anxiety, pain, delirium, etc.) and their coupled expiratory time decreases. The physiology resembles tension pneumothorax in that venous return is compromised leading to decreased cardiac performance, but no pleural space occupying lesion is present. Instead, pulmonary overdistension is the issue in this unique patient population. Tachycardia and hypotension as well as hypoxemia and hypercarbia ensue, the former especially related to decreased pulmonary flow. Therefore, the initial therapy of choice is to disconnect from the ventilator and allow for exhalation.Answer: DMosier JM and Hypes CD Mechanical ventilation strategies for the patient with severe obstructive lung disease. Emerg Med Clin. 2019; 37(3): 445–58. DOI: https://doi.org/10.1016/j.emc.2019.04.003
9 Infectious Disease
Rathnayaka M. K. Gunasingha, MD1, Patrick Benoit, DO1, and Matthew J. Bradley, MD2
1 Walter Reed National Military Medical Center, Bethesda, MD, USA
2 Uniformed Services University of the Health Sciences, Program Director General Surgery Residency, Walter Reed National Military Medical Center, Bethesda, MD, USA
1 A 28‐year‐old man is found by police obtunded with a respiratory rate of four per minute in a local park. He was administered naloxone in the field and transported to the hospital. On arrival, he continues to be lethargic with a blood pressure of 90/54 mm Hg, heart rate of 103/min, respiratory rate of 16/min, and temperature of 101.1o F.
