Higher age and obesity limit atelectasis formation during anaesthesia: an analysis of computed tomography data in 243 subjects.

BACKGROUND: General anaesthesia is increasingly common in elderly and obese patients. Greater age and body mass index (BMI) worsen gas exchange. We assessed whether this is related to increasing atelectasis during general anaesthesia. METHODS: This primary analysis included pooled data from previously published studies of 243 subjects aged 18-78 yr, with BMI of 18-52 kg m-2. The subjects had no clinical signs of cardiopulmonary disease, and they underwent computed tomography (CT) awake and during anaesthesia before surgery after preoxygenation with an inspired oxygen fraction (FIO2) of >0.8, followed by mechanical ventilation with FIO2 of 0.3 or higher with no PEEP. Atelectasis was assessed by CT. RESULTS: Atelectasis area of up to 39 cm2 in a transverse scan near the diaphragm was seen in 90% of the subjects during anaesthesia. The log of atelectasis area was related to a quadratic function of (age+age2) with the most atelectasis at ∼50 yr (r2=0.08; P<0.001). Log atelectasis area was also related to a broken-line function of the BMI with the knee at 30 kg m-2 (r2=0.06; P<0.001). Greater atelectasis was seen in the subjects receiving FIO2 of 1.0 than FIO2 of 0.3-0.5 (12.8 vs 8.1 cm2; P<0.001). A multiple regression analysis, including a quadratic function of age, a broken-line function of the BMI, and dichotomised FIO2 (0.3-0.5/1.0) adjusting for ventilatory frequency, strengthened the association (r2=0.23; P<0.001). PaO2 decreased with both age and BMI. CONCLUSIONS: Atelectasis during general anaesthesia increased with age up to 50 yr and decreased beyond that. Atelectasis increased with BMI in normal and overweight patients, but showed no further increase in obese subjects (BMI ≥30 kg m-2). Therefore, greater age and obesity appear to limit atelectasis formation during general anaesthesia.

Optimal PEEP during one-lung ventilation with capnothorax: An experimental study.

BACKGROUND: One-lung ventilation (OLV) with induced capnothorax carries the risk of severely impaired ventilation and circulation. Optimal PEEP may mitigate the physiological perturbations during these conditions. METHODS: Right-sided OLV with capnothorax (16 cm H2 O) on the left side was initiated in eight anesthetized, muscle-relaxed piglets. A recruitment maneuver and a decremental PEEP titration from PEEP 20 cm H2 O to zero end-expiratory pressure (ZEEP) was performed. Regional ventilation and perfusion were studied with electrical impedance tomography and computer tomography of the chest was used. End-expiratory lung volume and hemodynamics were recorded and. RESULTS: PaO2 peaked at PEEP 12 cm H2 O (49 ± 14 kPa) and decreased to 11 ± 5 kPa at ZEEP (P < 0.001). PaCO2 was 9.5 ± 1.3 kPa at 20 cm H2 O PEEP and did not change when PEEP step-wise was reduced to 12 cm H2 O PaCO2. At lower PEEP, PaCO2 increased markedly. The ventilatory driving pressure was lowest at PEEP 14 cm H2 O (19.6 ± 5.8 cm H2 O) and increased to 38.3 ± 6.1 cm H2 O at ZEEP (P < 0.001). When reducing PEEP below 12-14 cm H2 O ventilation shifted from the dependent to the nondependent regions of the ventilated lung (P = 0.003), and perfusion shifted from the ventilated to the nonventilated lung (P = 0.02). CONCLUSION: Optimal PEEP was 12-18 cm H2 O and probably relates to capnothorax insufflation pressure. With suboptimal PEEP, ventilation/perfusion mismatch in the ventilated lung and redistribution of blood flow to the nonventilated lung occurred.

Outbreak of enterovirus D68 of the new B3 lineage in Stockholm, Sweden, August to September 2016.

We report an enterovirus D68 (EV-D68) outbreak in Stockholm Sweden in 2016. Between 22 August and 25 September EV-D68 was detected in 74/495 respiratory samples analysed at the Karolinska University Hospital. During the peak week, 30/91 (33%) samples were EV-D68 positive. Viral protein (VP)P4/VP2 sequencing revealed that cases were caused by B3 lineage strains. Forty-four (59%) EV-D68-positive patients were children aged ≤ 5 years. Ten patients had severe respiratory or neurological symptoms and one died.

Acute necrotizing encephalopathy with SARS-CoV-2 RNA confirmed in cerebrospinal fluid.

Here, we report a case of COVID-19-related acute necrotizing encephalopathy where SARS-CoV-2 RNA was found in CSF 19 days after symptom onset after testing negative twice. Although monocytes and protein levels in CSF were only marginally increased, and our patient never experienced a hyperinflammatory state, her neurologic function deteriorated into coma. MRI of the brain showed pathologic signal symmetrically in central thalami, subinsular regions, medial temporal lobes, and brain stem. Extremely high concentrations of the neuronal injury markers neurofilament light and tau, as well as an astrocytic activation marker, glial fibrillary acidic protein, were measured in CSF. Neuronal rescue proteins and other pathways were elevated in the in-depth proteomics analysis. The patient received IV immunoglobulins and plasma exchange. Her neurologic status improved, and she was extubated 4 weeks after symptom onset. This case report highlights the neurotropism of SARS-CoV-2 in selected patients and emphasizes the importance of repeated lumbar punctures and CSF analyses in patients with suspected COVID-19 and neurologic symptoms.

Prevention of atelectasis in morbidly obese patients during general anesthesia and paralysis: a computerized tomography study.

BACKGROUND: Morbidly obese patients show impaired pulmonary function during anesthesia and paralysis, partly due to formation of atelectasis. This study analyzed the effect of general anesthesia and three different ventilatory strategies to reduce the amount of atelectasis and improve respiratory function. METHODS: Thirty patients (body mass index 45 +/- 4 kg/m) scheduled for gastric bypass surgery were prospectively randomized into three groups: (1) positive end-expiratory pressure of 10 cm H2O (PEEP), (2) a recruitment maneuver with 55 cm H2O for 10 s followed by zero end-expiratory pressure, (3) a recruitment maneuver followed by PEEP. Transverse lung computerized tomography scans and blood gas analysis were recorded: awake, 5 min after induction of anesthesia and paralysis at zero end-expiratory pressure, and 5 min and 20 min after intervention. In addition, spiral computerized tomography scans were performed at two occasions in 23 of the patients. RESULTS: After induction of anesthesia, atelectasis increased from 1 +/- 0.5% to 11 +/- 6% of total lung volume (P < 0.0001). End-expiratory lung volume decreased from 1,387 +/- 581 ml to 697 +/- 157 ml (P = 0.0014). A recruitment maneuver + PEEP reduced atelectasis to 3 +/- 4% (P = 0.0002), increased end-expiratory lung volume and increased Pao2/Fio2 from 266 +/- 70 mmHg to 412 +/- 99 mmHg (P < 0.0001). PEEP alone did not reduce the amount of atelectasis or improve oxygenation. A recruitment maneuver + zero end-expiratory pressure had a transient positive effect on respiratory function. All values are presented as mean +/- SD. CONCLUSIONS: A recruitment maneuver followed by PEEP reduced atelectasis and improved oxygenation in morbidly obese patients, whereas PEEP or a recruitment maneuver alone did not.

Lung complications are common in intensive care treated patients with pelvis fractures: a retrospective cohort study.

BACKGROUND: The incidence of severe respiratory complications in patients with pelvis fractures needing intensive care have not previously been studied. Therefore, the aims of this registry study were to 1) determine the number of ICU patients with pelvis fractures who had severe respiratory complications 2) whether the surgical intervention in these patients is associated with the pulmonary condition and 3) whether there is an association between lung complications and mortality. We hypothesized that acute hypoxic failure (AHF) and acute respiratory distress syndrome (ARDS) 1) are common in ICU treated patients with pelvis fractures, 2) are not related to the reconstructive surgery, or to 3) to mortality. METHODS: All patients in the database cohort (n = 112), scheduled for surgical stabilization of pelvis ring and/or acetabulum fractures, admitted to the general ICU at Uppsala University Hospital between 2007 and 2014 for intensive care were included. RESULTS: The incidence of AHF/ARDS was 67 % (75/112 patients), i.e., the percentage of patients that at any period during the ICU stay fulfilled the AHF/ARDS criteria. The incidence of AHF was 44 % and incidence of ARDS was 23 %. The patients with AHF/ARDS had more lung contusions and pneumonia than the patients without AHF/ARDS. Overall, there were no significant changes in oxygenation variables associated with surgery. However, 23 patients with pre-operative normal lung status developed AHF/ARDS in relation to the surgical procedure, whereas 12 patients with AHF/ARDS normalized their lung condition. The patients who developed AHF/ARDS had a higher incidence of lung contusion (P = 0.04) and the surgical stabilization was performed earlier (5 versus 10 days) in these patients (P = 0.03). CONCLUSIONS: We found that the incidence of respiratory failure in ICU treated patients with pelvis fractures was high, that the procedure around surgical stabilization seems to be associated with a worsening in the respiratory function in patients with lung contusion, and that mortality was low and was probably not related to the respiratory condition. TRIAL REGISTRATION: Study was registered at ISRCTN.org number, ISRCTN10335587 .

Maintenance of airway pressure during filter exchange due to auto-triggering.

BACKGROUND: Daily routine ventilator-filter exchange interrupts the integrity of the ventilator circuit. We hypothesized that this might reduce positive airway pressure in mechanically ventilated ICU patients, inducing alveolar collapse and causing impaired oxygenation and compliance of the respiratory system. METHODS: We studied 40 consecutive ICU subjects (P(aO2)/F(IO2) ratio ≤ 300 mm Hg), mechanically ventilated with pressure-regulated volume control or pressure support and PEEP ≥ 5 cm H2O. Before the filter exchange, (baseline) tidal volume, breathing frequency, end-inspiratory plateau pressure, and PEEP were recorded. Compliance of the respiratory system was calculated; F(IO2), blood pressure, and pulse rate were registered; and P(aO2), P(aCO2), pH, and base excess were measured. Measurements were repeated 15 and 60 min after the filter exchange. In addition, a bench test was performed with a precision test lung with similar compliance and resistance as in the clinical study. RESULTS: The exchange of the filter took 3.5 ± 1.2 s (mean ± SD). There was no significant change in P(aO2) (89 ± 16 mm Hg at baseline vs 86 ± 16 mm Hg at 15 min and 88 ± 18 mm Hg at 60 min, P = .24) or in compliance of the respiratory system (41 ± 11 mL/cm H2O at baseline vs 40 ± 12 mL/cm H2O at 15 min and 40 ± 12 mL/cm H2O at 60 min, P = .32). The bench study showed that auto-triggering by the ventilator when disconnecting from the expiratory circuit kept the tracheal pressure above PEEP for at least 3 s with pressure controlled ventilation. CONCLUSIONS: This study showed that a short disconnection of the expiratory ventilator circuit from the ventilator during filter exchange was not associated with any significant deterioration in lung function 15 and 60 min later. This result may be explained by auto-triggering of the ventilator with high inspiratory flows during the filter exchange, maintaining airway pressure.

Severe diabetic ketoacidosis in combination with starvation and anorexia nervosa at onset of type 1 diabetes: a case report.

We here report a case of diabetic ketoacidosis at onset of type 1 diabetes after a prolonged period of starvation due to anorexia nervosa. A 53-year-old female with a history of anorexia nervosa was admitted to the psychiatric clinic due to psychotic behaviour and inability to take care of herself. Twenty-four hours after admission she was transferred to the clinic of internal medicine due to altered mental status, and laboratory screening revealed a pH of 6.895 and blood glucose concentration of 40 mmol/L. Due to the unusual combination of prolonged starvation and diabetic ketoacidosis we implemented some modifications of existing treatment guidelines and some special considerations regarding nutrition in order to prevent a re-feeding syndrome.