Nighttime intensivist staffing and mortality

Dr. Chang

Wallace DJ, Angus DC et al. Nighttime intensivist staffing and mortality among critically ill patients. NEJM 366; 2093: 2012.

Summary: 

There has been an increasingly hot debate regarding the degree to which nighttime intensivists are associated with improvements in the quality of ICU care. Proponents suggest nighttime intensivists provide earlier establishment of treatment plans, more timely resuscitation of unstable patients, and more consistent decision-making all hours of the day. Opponents feel intensivists at night contribute to a high cost of hospitals' investments and that most judgment is based on lack of concrete evidence. Two prior studies showed: benefit of nighttime staffing involved in ICU care with low-intensity daytime staffing (Lancet, 2000); and no reduction for in-hospital mortality after adding night intensivists to already high-intensity staffing.

In brief, the study in this article was conducted over 2009-2010 and designed surveys were sent out to clinical coordinators at sites that utilize the APACHE scoring system. The primary outcome variable was in-hospital mortality (excluded patient discharged to hospice care). Multiple statistical analyses were performed, which included multivariate models to assess a relationship between nighttime intensivist staffing and in-hospital mortality. Adjustments were made for daytime intensivist staffing, illness severity, and case mix. Results were based on 65,752 (66% of total ICU admission) admitted to 49 ICUs in 25 hospitals:

- LOW-intensity daytime staffing: nighttime staffing associated with reduction in risk-adjusted in-hospital mortality (P=0.04)

- HIGH-intensity daytime staffing: no benefit with respect to risk-adjusted in-hospital mortality (P=0.78)

The discussion suggests that nighttime intensivists are more accessible to nursing staff and other providers, which ultimately aims to reduce medical errors. This is especially applicable in the setting of sepsis where studies have shown that rapid assessment improves outcomes. Limitations discussed included: lack of a random sample, definition of ‘nighttime’ broad in that it did not measure individualized clinical behavior, and that it did not evaluate increasing role of ICU telemedicine. In concluded that a general endorsement of 24-hour intensivist coverage is premature.

Cerebral Oximetry

Dr. Chang

Cerebral Oximetry: Monitoring the Brain as the Index Organ

Anesthesiology. January 2011, Volume 114, Issue 1, pages 12-13.

Note: the influence of this article comes from observing increased use of cerebral oximetry at a top-rated U.S. institution with a high volume of on-pump cardiac surgeries. (HC)

A prospective evaluation of 1,178 consecutive adult patients undergoing on-pump cardiac surgery, showed by Heringlake et al., presented compelling evidence that baseline cerebral oxygen saturation (Sco₂) is an independent risk factor for 30-day and one-year mortality.

A general idea behind cerebral oximetry goes as such: cerebral autoregulation reflects the coupling of cerebral oxygen delivery to cerebral metabolic rate and occurs primarily via modulation of cerebral blood flow in the presence of decreased cerebral arterial oxygen content. This is postulated either due to hypoxemia or moderate hemodilution. This study alluded to the failure of oxygen supplementation to increase Sco₂ beyond a cut-off value of about 50% indicated the potential for significantly higher morbidity and mortality.

One challenge of cerebral oximetry is the fact that perturbations in Sco₂, although highly sensitive, are conversely relatively nonspecific. Like any other perioperative parameter, it is for the clinician to determine whether a decrease in Sco₂ reflects a derangement of systemic perfusion, regional cerebral hypoperfusion, relative hypoxemia, increased cerebral metabolic rate, or some other such combination of factors. The numeric value should complement the larger clinical picture.

Now the study by Heringlake et al. looked at on-pump cardiac surgeries. Another study referenced in the article looked at a cohort of pediatric patients. If the observations can further be confirmed in various settings, the idea to employ this device as a sensitive, yet simple addition to the preoperative assessment of the non-cardiac patient may demonstrate similar findings and efficacy in the operating room.

Pediatric hyperglycemia and Brain Trauma, Dr. H. Chang

Helen A. Chang, DO

Article:
“Incidence and Risk Factors for Perioperative Hyperglycemia in Children with Traumatic Brain Injury.” Anesthesia and Analgesia. Jan 2009: 108(1): 81-89. Deepak Sharma, MD, Jill Jelacic, MD et al. Departmet of Anesthesiology, University of Washington, Seattle, WA.

Summary:

This was a retrospective cohort study of children < 13 years old you underwent urgent or emergent craniotomy for traumatic brain injury (TBI) at Harborview Medical Center. Data from 105 children were included and the main outcome was the incidence of hyperglycemia, defined as serum glucose > 200mg/dl at any given point during the pre-/intra-/postoperative period. Aside from the primary injury insult to the pediatric brain, secondary injury occurs as result of hypotension, hypoxia, increased ICP and hyperglycemia. These all contribute to poor outcomes, the intensive care length of stay, and in-hospital mortality.

The group’s main findings included: 1) perioperative hyperglycemia was common, 2) the sampling frequency for the majority of children was less than one serum glucose per “anesthetic hour,” 3) intraoperative hyperglycemia was common but few patients were treated with insulin, and 4) intraoperative hypoglycemia occurred independent of insulin treatment and in fact not rare. Despite the lack of consensus regarding the definition of hyperglycemia threshold for TBI in pediatric patients, the value of 200 was utilized as it is current clinical practice. No specific glycemic control guidelines have been published for pediatric TBI when this article was accepted. The issue still looms whether transient hyperglycemia after TBI should be treated. It was also clearly stated that hypoglycemia can be equally detrimental to the outcome. The data supports that there is an underestimation of both hypo-/hyperglycemia and that continuous perioperative glucose monitoring in children specifically with TBI may be needed.

Hypotension in OB Spinal Anesthesia, Dr. H. Chang

Helen A. Chang, DO

Article:
Hypotension in obstetric spinal anesthesia: a lesson from pre-eclampsia. G. Sharwood-Smith and
G.B. Drummond. British Journal of Anesthesia. 2009, 102 (3): 291-294.

Summary:
Vasopressors are oftentimes used to prevent hypotension after spinal anesthetics for cesarean section. Why expectant mothers become hypotensive may be due to several theories:

1. Spinal anesthesia almost always causes hypotension in normal pregnancy

2. Cardiac output can be reduced by aortocaval compression in the supine position from decreased venous return

3. A marked bradycardia with concomitant reduction in cardiac output and severe hypotension can occur suddenly

Many studies and therapies have been proposed to elude why drastic changes in hemodynamics may occur. There is no escape from the fact that therapies based on the concept of caval compression do not reliably prevent hypotension after a spinal technique. Compliance is more important than resistance in the venous system. Venous capacitance and its regulation in pregnancy are important in understanding the hemodynamic response to spinal anesthesia.

Sensors that normally autoregulate arterial pressure (carotid sinus and aorta) are part of the baroreflex pathway. Why does this reflex fail to maintain arterial pressure after spinal anesthesia in pregnancy? Answer is possibly seen in the pathophysiology of pre-eclampsia. In pre-eclampsia, vascular epithelium is damaged by placental-derived proteins, leading to an imbalance between pro-/anti-angiogenic growth factors. This results in persistent vasoconstriction. Sympathomimetic vasopressors to sustain arteriolar tone have become the most important strategy for safe spinal anesthesia in contemporary practice. This still holds despite the theory of caval occlusion as the culprit  for hypotension following a spinal in normal pregnancy

Laryngospasm in Children, Dr. Chang

Helen A. Chang, DO

Article:
Case Scenario: Perianesthetic Management of Laryngospasm in Children

Orliaguet, Gilles A., et al. Anesthesiology, February 2012. Vol 116, No 2, pgs 458-468.

Summary:

This article presented a case about a 10-year old male taken for an emergent incision and drainage for a fingertip abscess. Only remarkable history included a recent URI 4 weeks prior, but clear of symptoms at the time of surgery. The primary anesthetic utilized manual ventilation with 2% expired sevoflurane with a mixture of oxygen and nitrous oxide (50/50%). After a peripheral IV was established, sufentanil (1mcg) was administered for analgesia. Mask ventilation became difficult and respiratory stridor was noted. With rapidly developing hypoxia and bradycardia, jaw thrust maneuver, positive pressure ventilation with 100% oxygen, and two boluses of propofol (total 10mg) did not break the suspected laryngospasm. Atropine IV and succinylcholine (16mg) followed by tracheal intubation followed, which improved oxygenation.

Children are more prone to laryngospasm than adults (17.4/1000). Risk factors for perioperative laryngospasm include:

-        Sex: male > female

-        URI present at time of surgery, or within past 2 weeks

-        Wheezing during exercise, or > 3 events within past year

-        Nocturnal dry cough

-        Eczema present, or within past year

-        Family hx: at least 2 family members with asthma, atopy, eczema, or smoking

Possible ways to prevent and manage laryngospasm:

-        Delay elective surgery 2-3 weeks s/p URI

-        Although various studies do not provide a “gold standard” per se, generalized increased risk of laryngospasm (increasing rank) are: Mask > LMA > ETT

-        Sufficient depth of anesthesia important when placing or removing an airway device, regardless route of induction (i.e. intravenous versus inhalation)

-        Caution with negative pressure pulmonary edema

-        At emergence, provide adequate suctioning, check for residual paralysis (if muscle relaxant administered), limit stimulus in operating room setting until patient spontaneously opens eyes, and consider using “artificial cough technique”

-        If you suspect laryngospasm, be cognizant, act fast, and aggressive!

Neuraxial Anesthesia and Surgical Site Infection, Dr. Chang

Helen A. Chang, DO

Article:
Neuraxial Anesthesia and Surgical Site Infection

Sessler, Daniel I. M.D. Anesthesiology. Aug 2010 – Vol 113 – Issue 2, pp 265-267

Summary:

There is no 100% full proof method to avoid or prevent surgical site related infections. However, this article presents several methods from the anesthesia perspective that may wholly reduce surgical-specific infections. Three methods mentioned: induced hypothermia which reduces tissue oxygenation and thus impairs various immune functions; supplemental oxygen that increases FiO2 halves infection risk (although other studies show no difference) and enhances host defense against bacteria; and considering erythrocyte-based blood products stored less than 2 weeks.

The crux of the article mentioned utilizing neuraxial (i.e. spinal) versus general anesthesia, when clinically/surgically appropriate.  Three mechanisms supporting this theory included: reducing infection by vasodilation and improvement of tissue oxygenation; moderation of the inflammatory response and cascade markers to surgery; and hindering postoperative pain and thereby controlling the autonomic response. The remainder of the article proposes some details on how the study would be optimal to conduct with legitimate subjects and decreased bias.