Adrian Regli

Intra-abdominal hypertension and the abdominal compartment syndrome: updated consensus definitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome

PurposeTo update the World Society of the Abdominal Compartment Syndrome (WSACS) consensus definitions and management statements relating to intra-abdominal hypertension (IAH) and the abdominal compartment syndrome (ACS).MethodsWe conducted systematic or structured reviews to identify relevant studies relating to IAH or ACS. Updated consensus definitions and management statements were then derived using a modified Delphi method and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines, respectively. Quality of evidence was graded from high (A) to very low (D) and management statements from strong RECOMMENDATIONS (desirable effects clearly outweigh potential undesirable ones) to weaker SUGGESTIONS (potential risks and benefits of the intervention are less clear).ResultsIn addition to reviewing the consensus definitions proposed in 2006, the WSACS defined the open abdomen, lateralization of the abdominal musculature, polycompartment syndrome, and abdominal compliance, and proposed an open abdomen classification system. RECOMMENDATIONS included intra-abdominal pressure (IAP) measurement, avoidance of sustained IAH, protocolized IAP monitoring and management, decompressive laparotomy for overt ACS, and negative pressure wound therapy and efforts to achieve same-hospital-stay fascial closure among patients with an open abdomen. SUGGESTIONS included use of medical therapies and percutaneous catheter drainage for treatment of IAH/ACS, considering the association between body position and IAP, attempts to avoid a positive fluid balance after initial patient resuscitation, use of enhanced ratios of plasma to red blood cells and prophylactic open abdominal strategies, and avoidance of routine early biologic mesh use among patients with open abdominal wounds. NO RECOMMENDATIONS were possible regarding monitoring of abdominal perfusion pressure or the use of diuretics, renal replacement therapies, albumin, or acute component-parts separation.ConclusionAlthough IAH and ACS are common and frequently associated with poor outcomes, the overall quality of evidence available to guide development of RECOMMENDATIONS was generally low. Appropriately designed intervention trials are urgently needed for patients with IAH and ACS.

Elastic properties of the central airways in obstructive lung diseases measured using anatomical optical coherence tomography

RATIONALE Our understanding of how airway remodeling affects regional airway elastic properties is limited due to technical difficulties in quantitatively measuring dynamic, in vivo airway dimensions. Such knowledge could help elucidate mechanisms of excessive airway narrowing. OBJECTIVES To use anatomical optical coherence tomography (aOCT) to compare central airway elastic properties in control subjects and those with obstructive lung diseases. METHODS After bronchodilation, airway lumen area (Ai) was measured using aOCT during bronchoscopy in control subjects (n = 10) and those with asthma (n = 16), chronic obstructive pulmonary disease (COPD) (n = 9), and bronchiectasis (n = 8). Ai was measured in each of generations 0 to 5 while airway pressure was increased from -10 to 20 cm H(2)O. Airway compliance (Caw) and specific compliance (sCaw) were derived from the transpulmonary pressure (Pl) versus Ai curves. MEASUREMENTS AND MAIN RESULTS Caw decreased progressively as airway generation increased, but sCaw did not differ appreciably across the generations. In subjects with asthma and bronchiectasis, Caw and sCaw were similar to control subjects and the Pl-Ai curves were left-shifted. No significant differences were observed between control and COPD groups. CONCLUSIONS Proximal airway elastic properties are altered in obstructive lung diseases. Although central airway compliance does not differ from control subjects in asthma, bronchiectasis, or COPD, Ai is lower in asthma and the Pl-Ai relationship is left-shifted in both asthma and bronchiectasis, suggesting that airways are maximally distended at lower inflating pressures. Such changes reflect alteration in the balance between airway wall distensibility and radial traction exerted on airways by surrounding lung parenchyma favoring airway narrowing. Clinical trial registered with Australian New Zealand Clinical Trials Registry (ACTRN12607000624482).

Impact of spinal anaesthesia and obesity on maternal respiratory function during elective Caesarean section

Spinal anaesthesia for Caesarean section has gained widespread acceptance. We assessed the impact of spinal anaesthesia and body mass index (BMI) on spirometric performance. In this prospective study, we consecutively assessed 71 consenting parturients receiving spinal anaesthesia with hyperbaric bupivacaine and fentanyl for elective Caesarean section. We performed spirometry during the antepartum visit (baseline), immediately after spinal anaesthesia, 10–20 min, 1 h, 2 h after the operation, and after mobilisation (3 h). Baseline values were within normal ranges. There was a significant decrease in all spirometric parameters after effective spinal anaesthesia that persisted throughout the study period. The decrease in respiratory function was significantly greater in obese (BMI > 30 kg.m−2) than in normal‐weight parturients (BMI < 25 kg.m−2), e.g. median (IQR) vital capacity directly after spinal anaesthesia; −24 (−16 to −31)% vs. −11 (−6 to −16)%, p < 0.001 and recovery was significantly slower. We conclude that both spinal anaesthesia and obesity significantly impair respiratory function in parturients.

The impact of positive end-expiratory pressure on functional residual capacity and ventilation homogeneity impairment in anesthetized children exposed to high levels of inspired oxygen

BACKGROUND:High fractions of inspired oxygen (Fio2) result in resorption atelectasis shortly after their application. However, the impact of different levels of Fio2 and their interaction with positive end-expiratory pressure (PEEP) on functional residual capacity (FRC) and ventilation distribution is unknown in anesthetized children. We hypothesized that the use of a Fio2 of 1.0 results in a decrease of FRC and ventilation homogeneity compared with that of a Fio2 of 0.3, and that this decrease is prevented by PEEP of 6-cm H2O compared to a PEEP of 3-cm H2O. METHODS:Forty-six children (3–6 yr) without cardiopulmonary disease were randomly allocated to receive PEEP of 6-cm H2O (PEEP 6 group) during the entire study period or PEEP of 3-cm H2O (PEEP 3 group). The order of the Fio2 (0.3 or 1.0) was also randomized. A defined recruitment maneuver was performed after tracheal intubation and 5 min later the first measurement. This procedure was then repeated with the second Fio2 level. FRC and lung clearance index (LCI) were calculated by a blinded observer. RESULTS:While FRC (mean ± sd) was similar at both levels of Fio2 (0.3: 25.6 ± 2.9 mL/kg vs 1.0: 25.6 ± 2.8 mL/kg, P = 0.189) in the PEEP 6 group, FRC decreased in the PEEP 3 group (0.3: 24.9 ± 3.8 vs 1.0: 21.7 ± 4.1, P < 0.0001). Furthermore, with continuous PEEP of 6-cm H2O a similar LCI was observed at both levels of Fio2 (0.3: 6.45 ± 0.4 vs 6.43 ± 0.4, P = 0.668) while LCI increased at the higher Fio2 in the PEEP 3 group (0.3: 6.5 ± 0.5 vs 1.0: 7.7 ± 1.2, P < 0.0001). CONCLUSIONS:During the application of a very low PEEP of 3–cm H2O, FRC and ventilation distribution decreased significantly at an Fio2 of 1.0 compared with that at an Fio2 of 0.3. This decrease could be counterbalanced by the administration of PEEP of 6-cm H2O, indicating that a low level of PEEP is sufficient to maintain FRC and ventilation distribution regardless of the oxygen concentration.

Impact of spinal anaesthesia on peri-operative lung volumes in obese and morbidly obese female patients

Although obesity predisposes to postoperative pulmonary complications, data on the relationship between body mass index (BMI) and peri‐operative respiratory performance are limited. We prospectively studied the impact of spinal anaesthesia, obesity and vaginal surgery on lung volumes measured by spirometry in 28 patients with BMI 30–40 kg.m−2 and in 13 patients with BMI ≥ 40 kg.m−2. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, mid‐expiratory and peak expiratory flows were measured during the pre‐operative visit (baseline), after effective spinal anaesthesia with premedication, and after the operation at 20 min, 1 h, 2 h, and 3 h (after mobilisation). Spinal anaesthesia and premedication were associated with a significant decrease in spirometric parameters. Spinal anaesthesia and premedication were associated with a significant decrease in spirometric parameters; mean (SD) vital capacities were − 19% (6.4) in patients with BMI 30–40 kg.m−2 and − 33% (9.0) in patients with BMI > 40 kg.m−2. The decrease of lung volumes remained constant for 2 h, whereas 3 h after the operation and after mobilisation, spirometric parameters significantly improved in all patients. This study showed that both spinal anaesthesia and obesity significantly impaired peri‐operative respiratory function.

A deeper level of ketamine anesthesia does not affect functional residual capacity and ventilation distribution in healthy preschool children

Background:  Ketamine is commonly used in children in the emergency setting and while undergoing diagnostic and therapeutic interventions because of its combination of hypnotic and analgesic properties. Although studies comparing various levels of ketamine anesthesia are lacking, previous work suggests that lung mechanics might only be minimally affected by ketamine.

Comparison of perioperative spirometric data following spinal or general anaesthesia in normal-weight and overweight gynaecological patients

Background:  There is limited data comparing the impact of spinal anaesthesia (SA) and general anaesthesia (GA) on perioperative lung function. Here we assessed the differences of these two anaesthetic techniques on perioperative lung volumes in normal‐weight (BMI < 25) and overweight (BMI 25–30) patients using spirometry.

The impact of postoperative nasal packing on sleep-disordered breathing and nocturnal oxygen saturation in patients with obstructive sleep apnea syndrome.

Nasal septum surgery is frequently performed to establish a functional nasal airway. In these patients obstructive sleep apnea syndrome (OSAS) is frequently present. Although patients with OSAS are at increased risk for hypoxemia, the impact of postoperative nasal packing (PNP) on sleep-disordered breathing and oxygen desaturations in patients with OSAS is unknown. We consecutively investigated 40 patients undergoing endonasal surgery receiving PNP. Fifteen of these patients had previously diagnosed OSAS (Group 2) and 25 did not (Group 1). In the control group, 12 healthy patients underwent elective ear or neck surgery without PNP. During the preoperative and postoperative nights, we continuously measured oronasal flow, thoracoabdominal movements, and oxygen saturation. We calculated the apnea-hypopnea index (AHI) and the oxygen-desaturation index (ODI). Compared with the preoperative values, after the operation, neither AHI nor ODI changed in the control group. In contrast, in Group 1, AHI (from 11 [5–19] to 37 [22–49]) and ODI (from 4 [2–8] to 13 [6–21]) significantly increased (P < 0.05), whereas in Group 2, only AHI significantly increased (from 14 [10–21] to 39 [26–50]); ODI remained similar (13 [8–27] versus 11 [4–37]). Because ODI did not increase in patients with OSAS and PNP who received postoperative oxygen overnight, postoperative intensive care monitoring might not be necessary on a routine basis for all patients with PNP and OSAS.

Matching positive end-expiratory pressure to intra-abdominal pressure improves oxygenation in a porcine sick lung model of intra-abdominal hypertension

IntroductionIntra-abdominal hypertension (IAH) causes atelectasis, reduces lung volumes and increases respiratory system elastance. Positive end-expiratory pressure (PEEP) in the setting of IAH and healthy lungs improves lung volumes but not oxygenation. However, critically ill patients with IAH often suffer from acute lung injury (ALI). This study, therefore, examined the respiratory and cardiac effects of positive end-expiratory pressure in an animal model of IAH, with sick lungs.MethodsNine pigs were anesthetized and ventilated (48 +/- 6 kg). Lung injury was induced with oleic acid. Three levels of intra-abdominal pressure (baseline, 18, and 22 mmHg) were randomly generated. At each level of intra-abdominal pressure, three levels of PEEP were randomly applied: baseline (5 cmH2O), moderate (0.5 × intra-abdominal pressure), and high (1.0 × intra-abdominal pressure). We measured end-expiratory lung volumes, arterial oxygen levels, respiratory mechanics, and cardiac output 10 minutes after each new IAP and PEEP setting.ResultsAt baseline PEEP, IAH (22 mmHg) decreased oxygen levels (-55%, P <0.001) and end-expiratory lung volumes (-45%, P = 0.007). At IAP of 22 mmHg, moderate and high PEEP increased oxygen levels (+60%, P = 0.04 and +162%, P <0.001) and end-expiratory lung volume (+44%, P = 0.02 and +279%, P <0.001) and high PEEP reduced cardiac output (-30%, P = 0.04). Shunt and dead-space fraction inversely correlated with oxygen levels and end-expiratory lung volumes. In the presence of IAH, lung, chest wall and respiratory system elastance increased. Subsequently, PEEP decreased respiratory system elastance by decreasing chest wall elastance.ConclusionsIn a porcine sick lung model of IAH, PEEP matched to intra-abdominal pressure led to increased lung volumes and oxygenation and decreased chest wall elastance shunt and dead-space fraction. High PEEP decreased cardiac output. The study shows that lung injury influences the effects of IAH and PEEP on oxygenation and respiratory mechanics. Our findings support the application of PEEP in the setting of acute lung injury and IAH.

The effect of epidural analgesia in labour on maternal respiratory function

Lumbar epidural analgesia during labour has gained widespread acceptance. The impact of epidural analgesia based on mixtures of low‐dose local anaesthetic solutions and lipophilic opioids on most clinically relevant obstetric outcomes is minimal. Since the pregnant state per se is associated with important alterations in respiration, we assessed whether a subtle degree of motor blockade brought about by epidural analgesia might compromise respiratory function as assessed by spirometry. Sixty consenting parturients receiving epidural analgesia were consecutively included in this prospective study. We performed spirometry during the antepartum visit and in labour after effective epidural analgesia was established; at both assessments the women were pain‐free. Values were within normal ranges but increased significantly after effective epidural analgesia; median (IQR [range]) increase for vital capacity 7.4 (3.0–13 [−12–27])% (p < 0.001); forced vital capacity 4.4 (1.7–9.8 [−13–26])% (p < 0.001); forced expiratory volume in 1 s 5.5 (1.7–8.6 [−14–28])% (p < 0.001); and peak expiratory flow rate 2.3 (−1.6–5.8 [−18–16])% (p = 0.01)). We conclude that epidural analgesia for labour significantly improved respiratory function.