Category Archives: ICU

Stuff relevant to patients on ICU

All Updates, ICU, PHARM, Resus

Pre-hospital RSI and single use blades

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Single-use metal laryngoscope blades were compared in a randomised trial in the pre-hospital setting by French SAMU physicians. First-pass intubation success (defined as one advancement of the tube in the direction of the glottis during direct laryngoscopy) was similar between conventional and disposable metal blades.

A French doctor (not involved in the study)

STUDY OBJECTIVE: Emergency tracheal intubation is reported to be more difficult with single-use plastic than with reusable metal laryngoscope blades in both inhospital and out-of-hospital settings. Single-use metal blades have been developed but have not been compared with conventional metal blades. This controlled trial compares the efficacy and safety of single-use metal blades with reusable metal blades in out-of-hospital emergency tracheal intubation.
METHODS: This randomized controlled trial was carried out in France with out-of-hospital emergency medical units (Services de Médecine d’Urgence et de Réanimation). This was a multicenter prospective noninferiority randomized controlled trial in adult out-of-hospital patients requiring emergency tracheal intubation. Patients were randomly assigned to either single-use or reusable metal laryngoscope blades and intubated by a senior physician or a nurse anesthetist. The primary outcome was first-pass intubation success. Secondary outcomes were incidence of difficult intubation, need for alternate airway devices, and early intubation-related complications (esophageal intubation, mainstem intubation, vomiting, pulmonary aspiration, dental trauma, bronchospasm or laryngospasm, ventricular tachycardia, arterial desaturation, hypotension, or cardiac arrest).
RESULTS: The study included 817 patients, including 409 intubated with single-use blades and 408 with a reusable blade. First-pass intubation success was similar in both groups: 292 (71.4%) for single-use blades, 290 (71.1%) for reusable blades. The 95% confidence interval (CI) for the difference in treatments (0.3%; 95% CI -5.9% to 6.5%) did not include the prespecified inferiority margin of -7%. There was no difference in rate of difficult intubation (difference 3%; 95% CI -7% to 2%), need for alternate airway (difference 4%; 95% CI -8% to 1%), or early complication rate (difference 3%; 95% CI -3% to 8%).
CONCLUSION: First-pass out-of-hospital tracheal intubation success with single-use metal laryngoscopy blades was noninferior to first-pass success with reusable metal laryngoscope blades.

Out-of-Hospital Tracheal Intubation With Single-Use Versus Reusable Metal Laryngoscope Blades: A Multicenter Randomized Controlled Trial
Ann Emerg Med. 2011 Mar;57(3):225-31

Acute Med, All Updates, ICU

H1N1 or CAP?

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A scoring system composed of clinical, radiological, and laboratory variables purports to distinguish H1N1 influenza virus infection from community acquired pneumonia1. An accompanying editorial2 suggests that while further validation is required, the most useful application of the score might be in those with a score of 0 or 1 (out of 5), in whom the the high negative predictive value might safely avoid inpatient isolation and neuraminidase inhibitor treatment in the under-65s.

Background Early identification of patients with H1N1 influenza-related pneumonia is desirable for the early instigation of antiviral agents. A study was undertaken to investigate whether adults admitted to hospital with H1N1 influenza-related pneumonia could be distinguished clinically from patients with non-H1N1 community-acquired pneumonia (CAP).
Methods Between May 2009 and January 2010, clinical and epidemiological data of patients with confirmed H1N1 influenza infection admitted to 75 hospitals in the UK were collected by the Influenza Clinical Information Network (FLU-CIN). Adults with H1N1 influenza-related pneumonia were identified and compared with a prospective study cohort of adults with CAP hospitalised between September 2008 and June 2010, excluding those admitted during the period of the pandemic.
Results Of 1046 adults with confirmed H1N1 influenza infection in the FLU-CIN cohort, 254 (25%) had H1N1 influenza-related pneumonia on admission to hospital. In-hospital mortality of these patients was 11.4% compared with 14.0% in patients with inter-pandemic CAP (n=648). A multivariate logistic regression model was generated by assigning one point for each of five clinical criteria: age ≤65 years, mental orientation, temperature ≥38°C, leucocyte count ≤12×10(9)/l and bilateral radiographic consolidation. A score of 4 or 5 predicted H1N1 influenza-related pneumonia with a positive likelihood ratio of 9.0. A score of 0 or 1 had a positive likelihood ratio of 75.7 for excluding it.
Conclusion There are substantial clinical differences between H1N1 influenza-related pneumonia and inter-pandemic CAP. A model based on five simple clinical criteria enables the early identification of adults admitted with H1N1 influenza-related pneumonia.

1. Clinical and laboratory features distinguishing pandemic H1N1 influenza-related pneumonia from interpandemic community-acquired pneumonia in adults
Thorax. 2011 March; 66(3): 247–252 Free Full Text
2. Predicting the unpredictable: is it possible clinically to separate H1N1 from non-H1N1 community-acquired pneumonia?
Thorax. 2011 Mar;66(3):187-8

All Updates, ICU, Resus

More on Rocuronium (and Sugammadex)

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While I am gradually being persuaded rocuronium might after all be a better choice than suxamethonium for rapid sequence intubation in critically ill patients- partly due to its relative preservation of apnoea time before desaturation in elective anaesthesia patients1 – I don’t believe that the existence and availability of its reversal agent, sugammadex, should really sway us in critical care. After all, we’re usually committed to getting an airway of some description (tracheal tube, supraglottic airway, or cricothyrotomy), and the relatively short duration of suxamethonium has never allowed me to ‘wake someone up and cancel the case’ in a critical care scenario. In fact, with sux, even healthy patients will desaturate before it wears off 2-4 if one is unable to intubate or ventilate.

But could we give sugammadex and reverse the rocuronium in time to save the patient in a can’t intubate/can’t ventilate (CICV) situation? This was tested in a simulation that studied the total time taken for anaesthetic teams to prepare and administer sugammadex from the time of their initial decision to use the drug5. The mean (SD) total time to administration of sugammadex was 6.7 (1.5) min, following which a further 2.2 min (giving a total 8.9 min) should be allowed to achieve a train-of-four ratio of 0.9. Four (22%) teams gave the correct dose, 10 (56%) teams gave a dose that was lower than recommended.
 
A reply to this article6 recommended some steps to speed up and improve the process:

  1. Brief the team that rocuronium is to be used and that should an unanticipated difficult airway situation be encountered, then sugammadex will be used to reverse the effects of the rocuronium.
  2. Allocate the task of drawing up the sugammadex to a specific team member who has no additional role in the rapid sequence induction.
  3. Before induction, a calculation is made of the dose of sugammadex (16 mg/kg) that would be required and the volume of drug that should be drawn up.
  4. The instruction is given that should the anaesthetist not confirm intubation within 2 min, then the sugammadex is to be drawn up and handed to the anaesthetist for administration.


There are of course rare situations where sugammadex can be a nuisance – it hangs around in renal failure and a recent case report 7described rocuronium (50mg followed by 30mg, patient weight not stated) failing to work on an elderly man who had received sugammadex 16 hours earlier! The authors of this case report state that in healthy patients, the mean cumulative percentage of sugammadex excreted in the urine over 24 h is 48–86%; therefore, a period of 24 h is recommended before a second administration of rocuronium. However, a good dose of rocuronium (1.2 mg/kg) should be effective after sugammadex reversal in previously healthy patients, but a study showed onset was slower and duration shorter if the second dose of rocuronium was given within 25 minutes of the sugammadex8.
So what are the take home points here? For me, the issues are:

  • Suxamethonium offers no real advantages over rocuronium for RSI in critical care – rocuronium at a dose of 1.2 mg/kg will provide similar intubating conditions to a good dose of sux9
  • Whatever you use, you need a rescue plan (supraglottic airway or transtracheal airway) for the CICV scenario
  • Sugammadex is a useful reversal agent in elective anaesthesia but is unlikely to be useful in a critical care scenario; however, if its use is anticipated it needs to be rehearsed as a standardised drill
  • Most of the literature on these agents pertains to well patients undergoing elective anaesthesia and we should be cautious about extrapolating results to the critical care setting
  • Finally, the urgency of a CICV can be reduced by CICVBCO – ‘can’t intubate, can’t ventilate, but CAN oxygenate’ – apnoeic diffusion oxygenation should be employed using pharyngeal or nasal oxygen10. Such a simple but underutilised technique can hugely improve the safety of RSI in critical care, and is described here.

1. Effect of suxamethonium vs rocuronium on onset of oxygen desaturation during apnoea following rapid sequence induction
Anaesthesia. 2010 Apr;65(4):358-61
2. Critical hemoglobin desaturation will occur before return to an unparalyzed state following 1 mg/kg intravenous succinylcholine.
Anesthesiology. 1997 Oct;87(4):979-8
3. Hemoglobin desaturation after succinylcholine-induced apnea: a study of the recovery of spontaneous ventilation in healthy volunteers.
Anesthesiology. 2001 May;94(5):754-9
4. Succinylcholine dosage and apnea-induced hemoglobin desaturation in patients
Anesthesiology. 2005 Jan;102(1):35-40
5. Can sugammadex save a patient in a simulated ‘cannot intubate, cannot ventilate’ situation?
Anaesthesia. 2010 Sep;65(9):936-41
6. Can sugammadex save a patient in a simulated ‘cannot intubate, cannot ventilate’ situation?
Anaesthesia. 2011 Mar;66(3):223-4
7. Unexpected failure of rocuronium-mediated neuromuscular blockade
Anaesthesia. 2011 Jan;66(1):58-9
8. Repeat dosing of rocuronium 1.2 mg kg−1 after reversal of neuromuscular block by sugammadex 4.0 mg kg−1 in anaesthetized healthy volunteers: a modelling-based pilot study
Br J Anaesth. 2010 Oct;105(4):487-92
9. Comparison of Succinylcholine and Rocuronium for First-attempt Intubation Success in the Emergency Department
Acad Emerg Med. 2011;18:11-14
10. Critical hemoglobin desaturation can be delayed by apneic diffusion oxygenation
Anesthesiology. 1999 Jan;90(1):332-3

All Updates, ICU, Resus

Neuromuscular blockade facilitates mask ventilation

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A blinded randomised controlled trial of rocuronium versus saline in anaesthetised patients demonstrated that mask ventilation was easier in paralysed patients.
The authors comment on the implications of this finding:
‘Our finding that neuromuscular blockade facilitates mask ventilation has important implications for the practice of managing difficult or impossible mask ventilation after administration of these drugs. Options in this case include returning to spontaneous ventilation, tracheal intubation, placement of a supraglottic airway device or obtaining emergency invasive airway access. In most cases, returning to spontaneous ventilation is not practical in a reasonable time frame, leaving tracheal intubation, supraglottic airway placement or emergency invasive airway access as the only feasible choices. Considerable evidence exists indicating that neuromuscular blockade facilitates tracheal intubation; and since our data further indicate that neuromuscular blockade facilitates mask ventilation, it follows that administering neuromuscular blockade is an advantage, rather than a hindrance when given early in a case of unrecognised difficult mask ventilation.‘
ABSTRACT
We wished to test the hypothesis that neuromuscular blockade facilitates mask ventilation. In order reliably and reproducibly to assess the efficiency of mask ventilation, we developed a novel grading scale (Warters scale), based on attempts to generate a standardised tidal volume. Following induction of general anaesthesia, a blinded anaesthesia provider assessed mask ventilation in 90 patients using our novel grading scale. The non-blinded anaesthesiologist then randomly administered rocuronium or normal saline. After 2 min, mask ventilation was reassessed by the blinded practitioner. Rocuronium significantly improved ventilation scores on the Warters scale (mean (SD) 2.3 (1.6) vs 1.2 (0.9), p<0.001). In a subgroup of patients with a baseline Warters scale value of >3 (i.e. difficult to mask ventilate; n=14), the ventilation scores also showed significant improvement (4.2 (1.2) vs 1.9 (1.0), p=0.0002). Saline administration had no effect on ventilation scores. Our data indicate that neuromuscular blockade facilitates mask ventilation. We discuss the implications of this finding for unexpected difficult airway management and for the practice of confirming adequate mask ventilation before the administration of neuromuscular blockade.
The effect of neuromuscular blockade on mask ventilation
Anaesthesia. 2011 Mar;66(3):163-7

Acute Med, All Updates, ICU, Resus

Nasal cooling method

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More data on the RhinoChill device from an in-hospital study of post-cardiac arrest patients in Germany. The RhinoChill device (BeneChill Inc., San Diego, USA) allows evaporative cooling by spraying an inert liquid coolant (a perfluorochemical) into the nasal cavity. The liquid evaporates instantaneously, thereby removing heat. It can make your nose discoloured, and in one patient with cardiogenic shock, tissue damage of nose and cheeks due to freezing occurred. Several of the authors are linked with the company that manufactures the device.

AIM: Mild therapeutic hypothermia improves survival and neurologic recovery in primary comatose survivors of cardiac arrest. Cooling effectivity, safety and feasibility of nasopharyngeal cooling with the RhinoChill device (BeneChill Inc., San Diego, USA) were determined for induction of therapeutic hypothermia.
METHODS: Eleven emergency departments and intensive care units participated in this multi-centre, single-arm descriptive study. Eighty-four patients after successful resuscitation from cardiac arrest were cooled with nasopharyngeal delivery of an evaporative coolant for 1h. Subsequently, temperature was controlled with systemic cooling at 33 degrees C. Cooling rates, adverse events and neurologic outcome at hospital discharge using cerebral performance categories (CPC; CPC 1=normal to CPC 5=dead) were documented. Temperatures are presented as median and the range from the first to the third quartile.
RESULTS: Nasopharyngeal cooling for 1h reduced tympanic temperature by median 2.3 (1.6; 3.0) degrees C, core temperature by 1.1 (0.7; 1.5) degrees C. Nasal discoloration occurred during the procedure in 10 (12%) patients, resolved in 9, and was persistent in 1 (1%). Epistaxis was observed in 2 (2%) patients. Periorbital gas emphysema occurred in 1 (1%) patient and resolved spontaneously. Thirty-four of 84 patients (40%) patients survived, 26/34 with favorable neurological outcome (CPC of 1-2) at discharge.
CONCLUSIONS: Nasopharyngeal evaporative cooling used for 1h in primary cardiac arrest survivors is feasible and safe at flow rates of 40-50L/min in a hospital setting.
Safety and feasibility of nasopharyngeal evaporative cooling in the emergency department setting in survivors of cardiac arrest
Resuscitation. 2010 Aug;81(8):943-9

All Updates, ICU, PHARM, Resus

Difficult tube – Easytube

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French pre-hospital physicians included the Easytube, which is similar to the Combitube, in their difficult airway algorithm. They describe the insertion method as:
“ ..inserted blindly, the patient’s head must be in neutral position. Manually opening the patient’s mouth and pressing the tongue gently toward the mandible, the tube is inserted parallel to the frontal axis of the patient until the proximal black ring mark is positioned at the level of the incisors. If the EzT is inserted blindly, the tip is likely to be positioned in the esophagus with a probability of more than 95% [3]. Ventilation of the patient should be performed using a colored lumen, and the transparent lumen can then be used to insert a gastric tube or to drain gastric contents.”
The authors suggest that the main advantages of the Ezt are: shorter insertion time for Ezt than for ETI, better protection against aspiration than a laryngeal mask and the possibility of blind insertion of the Ezt in patients trapped in a sitting position.
BACKGROUND: Securing the airway in emergency is among the key requirements of appropriate prehospital therapy. The Easytube (Ezt) is a relatively new device, which combines the advantages of both an infraglottic and supraglottic airway.
AIMS: Our goal was to evaluate the effectiveness and the safety of use of Ezt by emergency physicians in case of difficult airway management in a prehospital setting with minimal training.

METHODS: We performed a prospective multi-centre observational study of patients requiring airway management conducted in prehospital emergency medicine in France by 3 French mobile intensive care units from October 2007 to October 2008.
RESULTS: Data were available for 239 patients who needed airway management. Two groups were individualized: the “easy airway management” group (225 patients; 94%) and the “difficult airway management” group (14 patients; 6%). All patients had a successful airway management. The Ezt was used in eight men and six women; mean age was 64 years. It was used for ventilation for a maximum of 150 min and the mean time was 65 min. It was positioned successfully at first attempt, except for two patients, one needed an adjustment because of an air leak, and in the other patient the Ezt was replaced due to complete obstruction of the Ezt during bronchial suction.
CONCLUSION: The present study shows that emergency physicians in cases of difficult airway management can use the EzT safely and effectively with minimal training. Because of its very high success rate in ventilation, the possibility of blind intubation, the low failure rate after a short training period. It could be introduced in new guidelines to manage difficult airway in prehospital emergency.
The Easytube for airway management in prehospital emergency medicine
Resuscitation. 2010 Nov;81(11):1516-20

All Updates, ICU, Kids, PHARM, Resus

Laryngospasm and ketamine

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What are the factors associated with laryngospasm in ketamine sedation? A large study was unable to identify specific predictors:
Objective: The objective of this study was to assess predictors of emergency department (ED) ketamine-associated laryngospasm using case-control techniques.
Methods: We performed a matched case-control analysis of a sample of 8282 ED ketamine sedations (including 22 occurrences of laryngospasm) assembled from 32 prior published series. We sequentially studied the association of each of 7 clinical variables with laryngospasm by assigning 4 controls to each case while matching for the remaining 6 variables. We then used univariate statistics and conditional logistic regression to analyze the matched sets.

Results: We found no statistical association of age, dose, oropharyngeal procedure, underlying physical illness, route, or coadministered anticholinergics with laryngospasm. Coadministered benzodiazepines showed a borderline association in the multivariate but not univariate analysis that was considered anomalous.
Conclusions: This case-control analysis of the largest available sample of ED ketamine-associated laryngospasm did not demonstrate evidence of association with age, dose, or other clinical factors. Such laryngospasm seems to be idiosyncratic, and accordingly, clinicians administering ketamine must be prepared for its rapid identification and management. Given no evidence that they decrease the risk of laryngospasm, coadministered anticholinergics seem unnecessary.
Laryngospasm During Emergency Department Ketamine Sedation: A Case-Control Study
Pediatr Emerg Care. 2010 Nov;26(11):798-802

All Updates, ICU, Resus, Trauma

Plasma:red cell ratios

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In some circles, ‘wuntwuntwun’ is in danger of becoming the new dogma of trauma fluid replacement (ie. 1 unit of plasma and 1 unit of platelets for every unit of red cells). Since it takes longer to thaw some plasma than it does to throw in some O negative packed red cells, some really sick patients may be dead before they get the plasma, biasing comparisons that show a reduced mortality in patients who were still alive to receive plasma. This ‘survivor bias’ has been suggested as a reason that high plasma:red cell ratios are associated with mortality reduction, although this has been challenged.
The survivor bias explanation receives some new support by the following (small) study from Journal of Trauma:
BACKGROUND: In light of recent data, controversy surrounds the apparent 30-day survival benefit of patients achieving a fresh frozen plasma (FFP) to packed red blood cell (PRBC) ratio of at least 1:2 in the face of massive transfusions (MT) (≥10 units of PRBC within 24 hours of admission). We hypothesized that initial studies suffer from survival bias because they do not consider early deaths secondary to uncontrolled exsanguinating hemorrhage. To help resolve this controversy, we evaluated the temporal relationship between blood product administration and mortality in civilian trauma patients receiving MT.

METHODS: Patients requiring MT over a 22-month period were identified from the resuscitation registry of a Level I trauma center. Shock severity at admission and timing of shock-trauma admission, blood product administration, and death were determined. Patients were divided into high- and low-ratio groups (≥1:2 and<1:2 FFP:PRBC, respectively) and compared. Kaplan-Meier analysis and log-rank test was used to examine 24-hour survival.
RESULTS: One hundred three patients (63% blunt) were identified (66 high-ratio and 37 low-ratio). Those patients who achieved a high-ratio in 24 hours had improved survival. However, severity of shock was less in the high-group (base excess: -8.0 vs. -11.2, p=0.028; lactate: 6.3 vs. 8.4, p=0.03). Seventy-five patients received MT within 6 hours. Of these, 29 received a high-ratio in 6 hours. Again, severity of shock was less in the high-ratio group (base excess: -7.6 vs. -12.7, p=0.008; lactate: 6.7 vs. 9.4, p=0.02). For these patients, 6-hour mortality was less in the high-group (10% vs. 48%, p<0.002). After accounting for early deaths, groups were similar from 6 hours to 24 hours.
CONCLUSIONS: Improved survival was observed in patients receiving a higher plasma ratio over the first 24 hours. However, temporal analysis of mortality using shorter time periods revealed those who achieve early high-ratio are in less shock and less likely to die early from uncontrolled hemorrhage compared with those who never achieve a high-ratio. Thus, the proposed survival advantage of a high-ratio may be because of selection of those not likely to die in the first place; that is, patients die with a low-ratio not because of a low-ratio.
The authors state “The current study underscores the need for well-designed prospective studies to address the important question of which ratio results in improved survival and stresses the importance of timing of blood product administration as this may impact survival.”
Improved survival after hemostatic resuscitation: does the emperor have no clothes?
J Trauma. 2011 Jan;70(1):97-102

All Updates, ICU, PHARM, Resus, Trauma

GCS in intubated patients

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We use the Glasgow Coma Score to describe conscious level, derived from eye opening, verbal response, and motor response.
One problem is that if your patient is intubated, there can’t be a verbal response. There are some ways round this. Imagine your intubated patient opens eys to a painful stimulus and withdraws his limb from one:

  • Just give him the lowest score (1) for the verbal component – E2M4V1
  • Write ‘V’ (ventilated) or ‘T’ (tube), eg. E2M4VT
  • Make it up, based on what you would expect the V score to be based on the E and M scores.

Weird as it sounds, there is a model for this, demonstrated in the paper abstracted below. The Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233).

Don’t worry…if you really want to use this, you don’t have to memorise that equation; there is an online calculator for it here and if you try it you’ll see this patient gets a derived verbal score of 2.3, and therefore a GCS of 7.3! Your decision now whether to round up or down. (In the meantime, I’ve given the patient a V of 1 and called it GCS E2M4VT=7.)
Alternatively, of course, you could try a better validated score that gives more information, the FOUR score, as validated here. The problem is, most people won’t know what you’re talking about.
The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores.
Meredith W, Rutledge R, Fakhry SM, Emery S, Kromhout-Schiro S.
BACKGROUND: The Glasgow Coma Scale (GCS), which is the foundation of the Trauma Score, Trauma and Injury Severity Score, and the Acute Physiology and Chronic Health Evaluation scoring systems, requires a verbal response. In some series, up to 50% of injured patients must be excluded from analysis because of lack of a verbal component for the GCS. The present study extends previous work evaluating derivation of the verbal score from the eye and motor components of the GCS.
METHODS: Data were obtained from a state trauma registry for 24,565 unintubated patients. The eye and motor scores were used in a previously published regression model to predict the verbal score: Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233). The correlation of the actual and derived verbal and GCS scales were assessed. In addition the ability of the actual and derived GCS to predict patient survival in a logistic regression model were analyzed using the PC SAS system for statistical analysis. The predictive power of the actual and the predicted GCS were compared using the area under the receiver operator characteristic curve and Hosmer-Lemeshow goodness-of-fit testing.
RESULTS: A total of 24,085 patients were available for analysis. The mean actual verbal score was 4.4 +/- 1.3 versus a predicted verbal score of 4.3 +/- 1.2 (r = 0.90, p = 0.0001). The actual GCS was 13.6 + 3.5 versus a predicted GCS of 13.7 +/- 3.4 (r = 0.97, p = 0.0001). The results of the comparison of the prediction of survival in patients based on the actual GCS and the derived GCS show that the mean actual GCS was 13.5 + 3.5 versus 13.7 + 3.4 in the regression predicted model. The area under the receiver operator characteristic curve for predicting survival of the two values was similar at 0.868 for the actual GCS compared with 0.850 for the predicted GCS.
CONCLUSIONS: The previously derived method of calculating the verbal score from the eye and motor scores is an excellent predictor of the actual verbal score. Furthermore, the derived GCS performed better than the actual GCS by several measures. The present study confirms previous work that a very accurate GCS can be derived in the absence of the verbal component.
The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores.
J Trauma. 1998 May;44(5):839-44 (if you have full text access to Journal of Trauma the best bit about this article is the discussion on pages 844-5 in which surgeons wrestle with the meaning of the word ‘conundrum’ and the spelling of ‘Glasgow’).